JP2016011845A - Welding method and apparatus for heat transfer copper fin for metal cask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding method for a heat-transfer copper fin for metal cask that realizes excellent weldability in welding a different-material joint made of copper and steel, realizes a good-quality welded part having sufficient throat thickness and is effective for both improvement in heat removal performance and reduction in manufacturing cost, and to provide a welding device therefor.SOLUTION: A fillet joint part is welded between starting and end positions of a weld line by: outputting a prescribed range of a ratio Ia/Ib of first welding current Ia supplied from a TIG welding power source 15 to second welding current Ib supplied from a MIG welding power source 20; using repulsive magnetic force generated by both Ia of preceding TIG flowing to a non-consumable electrode 13 and Ib of subsequent MIG flowing to a CuSi wire to generate mutually-repulsive TIG arc 22 and MIG arc 23 at a weld starting position of the fillet joint part and to form one melt pool 24 with the mutually-repulsive TIG and MIG arcs; and applying composite weld to the TIG and MIG arcs and the melt pool.

Description

  The present invention relates to a method and apparatus for welding a heat transfer copper fin for a metal cask, and in particular, transports or stores or transports and stores spent fuel generated from a nuclear power plant, etc. The present invention relates to a method for welding a heat transfer copper fin for a metal cask suitable for a case where a copper heat transfer fin is directly welded to an outer cylinder, and a welding apparatus therefor.

  In general, a plurality of fuels used for a certain period in a nuclear power plant nuclear reactor are taken out of the nuclear reactor and temporarily stored in a spent fuel cooling pool or the like. Spent fuel that has been cooled in the spent fuel cooling pool for a specified period of time is stored in a radioactive material storage container called a metal cask to be used as a resource, and then transported to an intermediate storage facility until it is reprocessed at the reprocessing facility. Stored.

  A metal cask that transports and stores spent fuel assemblies consists of an inner cylinder (also referred to as an inner cylinder container, a container body, or a trunk body) that stores spent fuel, and an outer cylinder and an inner cylinder that absorb impact from the outside. It has a plurality of lids to be sealed.

  Since spent fuel contains a high level of radioactive material, it generates decay heat, so the decay heat generated from the spent fuel assembly is transferred between the inner and outer cylinders between the inner and outer cylinders. A plurality of heat transfer fins are provided to escape to the outside of the cylinder, and the plurality of heat transfer fins are welded to the inner cylinder and the outer cylinder, respectively.

  Usually, the material of the inner cylinder and the outer cylinder is a carbon steel material, stainless steel material, etc. with good performance such as rigidity and shielding property, and the material of one heat transfer fin is mainly a copper material with good heat conduction. Moreover, the copper clad steel material etc. which joined two types of metals previously are also used.

  For example, Patent Documents 1 to 5 disclose known techniques for welding heat transfer fins to the inner and outer surfaces of the metal cask described above.

  Patent Document 1 describes a method for manufacturing a metal container. A welding process for generating a MIG arc from a pure copper MIG wire, and a plasma arc from a plasma electrode arranged coaxially so as to surround the MIG arc are generated. The welding process is performed in parallel, and in the MIG welding process and the plasma welding process, the angle formed by the copper heat transfer fin and the horizontal plane is 15 to 20 degrees, and the angle formed by the heat transfer fin and the carbon steel inner cylinder. It is disclosed that the MIG arc and the plasma arc are generated in a downward direction by arranging them at 75 degrees or more.

  Patent Document 2 describes a welding method. A welding process of welding a steel base material and a copper base material requiring heat treatment after welding by a welding means such as a MIG torch; Heating (including melting) the welding bead generated in the welding process by heating means such as an arc welding torch, a high-frequency coil, or a laser disposed at a rear position away from the welding heat of the steel base material. A heat treatment step of heat-treating to the affected part, and further, before the welding step, by a heating means such as a TIG torch, a YAG laser, a high-frequency coil, etc. arranged at a front position ahead of the welding means by a predetermined distance, It is disclosed that the copper base material having a high thermal conductivity is preheated before the welding process.

  Patent Document 3 describes a method for welding copper or copper alloy, which combines a non-consumable electrode and a consumable electrode, and alternately supplies a welding current to a preceding non-consumable electrode and a subsequent consumable electrode, and It is disclosed that welding is performed while keeping the distance between the electrode and the consumable electrode at a distance that does not cause poor fusion beads.

  Patent Document 4 describes a metal cask for a radioactive material, and includes a heat transfer fin that extends radially outward from a trunk body and transfers heat to an outer cylinder. The heat transfer fin joins two types of metal plates. And one metal of the clad material is made of the same metal material for the body and outer cylinder, and the other is made of a good heat transfer material with good heat conduction, and the body ( And / or an outer tube) and a clad portion of the same kind of metal are directly welded.

  Further, Patent Document 5 describes a radioactive substance storage container, in which parallel portions are formed at both ends of the copper heat transfer fins, and the parallel portions are formed along the outer peripheral surface of the container main body and the inner peripheral surface of the outer cylinder. It is disclosed that the outer peripheral surface of the container body and the inner peripheral surface of the outer cylinder and the parallel tips of the heat transfer fins are welded by MIG welding or MIG brazing using a copper alloy wire.

JP 2009-178727 A JP 2002-361469 A JP 58-3791 A JP 2007-205931 A JP 2008-082906 A

  However, in Patent Document 1 described above, since the MIG arc and the plasma arc are generated almost coaxially, the electromagnetic forces acting on both arcs cancel each other, but the MIG wire (consumable electrode) and the plasma electrode (non-consumable) Since the polarity of the electrode is positive (plus) and the base metal side is negative (minus), the plasma electrode is easily consumed and damaged, so long members with long weld lines that require long-term operation It is not suitable for welding, and if the plasma electrode is consumed during welding, it may change to unstable arc behavior and adversely affect weld bead formation, leading to poor welding. In addition, pure copper is a material with high thermal conductivity. However, because dissimilar welding of copper and steel is not compatible and difficult to dissolve, the copper / steel joint is made of pure copper MIG wire. If the penetration on the steel side becomes deeper after welding, weld cracks (solidification cracks) are likely to occur.

  Moreover, in patent document 2, since it is the structure which provides heating means, such as an arc welding torch, a high frequency coil, or a laser, in the back position and / or the front position of this welding means, while an apparatus enlarges, The part which cannot be welded will generate | occur | produce by interference with a welding target object, etc. When a high frequency coil that generates magnetism is provided, the arc behavior of the welding means becomes unstable due to electromagnetic force, which may adversely affect the formation of the weld bead. On the other hand, when a laser is used, the copper base material cannot be heated sufficiently because the reflectance of light is high with respect to the copper base material.

  In Patent Document 3, in order to avoid interference between arcs, the current on the non-consumable electrode (TIG) side and the current on the consumable electrode (MIG) side are alternately switched and supplied. For this reason, when the TIG arc is generated, the MIG arc is extinguished, and conversely, during the generation of the MIG arc, the TIG arc is extinguished and the copper or copper alloy base material is welded. Therefore, it is difficult to significantly improve the welding efficiency. Moreover, a welding target object is welding between copper materials or between copper alloy materials, and about the dissimilar material welding of a copper material and steel materials, it is not applied outside the object, and neither description nor suggestion is made.

In Patent Document 4, since it is configured so as to weld the steel portion and the steel body or barrel of copper clad steel, although MAG welding and CO ₂ welding of steel materials to each other becomes possible construction Since the copper clad steel material is used for the heat transfer fin, there is a problem that the manufacturing cost is high and the weight is increased. In addition, since the copper clad steel material has a thin copper side, there is a limit to heat removal performance, so it is not suitable for heat transfer fins that require higher heat removal performance.

  Furthermore, in patent document 5, while using a copper plate with a wide plate | board width, it is a structure which requires processes, such as bending molding for providing a parallel part in the both ends of a copper plate width direction, and there exists a problem that manufacturing cost becomes high. is there. In addition, the parallel part is brought into close contact with the outer peripheral surface of the container body and the inner peripheral surface of the outer cylinder to form a lap fillet joint, and the lap fillet joint is subjected to MIG welding or MIG brazing. The amount of heat input is required, and further, a dent such as an undercut that is likely to occur at the weld bead toe on the copper side may lead to a lack of throat thickness or an insufficient effective cross-sectional area of the weld.

  The present invention has been made in view of the above-mentioned points. The object of the present invention is to obtain a welded part having a good quality and having a sufficient throat thickness with excellent weldability of a dissimilar joint between copper and steel. An object of the present invention is to provide a welding method and a welding apparatus for heat transfer copper fins for metal cask that are effective in improving heat removal performance and reducing manufacturing costs.

  In order to achieve the above object, a welding method for heat transfer copper fins for a metal cask according to the present invention includes an outer surface of a steel inner cylinder housing a collection of spent fuel having a radioactive substance, and an outer side of the inner cylinder. When welding both end surface portions of a predetermined number of copper heat transfer copper fins that are inclined and arranged at substantially equal intervals between the inner surface of the steel outer tube coaxially disposed on the outer surface of the inner tube The inner tube side wide-angle inclined fillet joint portion formed by abutting one end surface portion of the heat transfer copper fin in the direction, or the other end surface portion of the heat transfer copper fin in the longitudinal direction of the inner surface of the outer tube. Metal to be welded to the fillet joint portion of the outer cylinder side formed by butt contact, or the fillet joint portion formed on both surfaces of the inner cylinder and the outer cylinder by composite welding of the preceding TIG and the subsequent MIG In the welding method for heat transfer copper fins for cask, the fillet joint to be welded Using a TIG-MIG welding torch having an integral structure capable of composite welding of the preceding TIG and the subsequent MIG with respect to the weld line of the portion, and a CuSi wire containing silicon for the consumable wire on the subsequent MIG side, The TIG-MIG welding torch is attached to the tip of a long arm that can travel and move or the wrist of an articulated movable welding robot via an attachment jig, and the polarity of the non-consumable electrode of the preceding TIG is a negative electrode, Power supply with the fillet joint side polarity as the positive electrode is performed with the TIG welding power source, while power supply with the polarity of the CuSi wire of the subsequent MIG as the positive electrode and the polarity on the fillet joint side as the negative electrode is performed with the MIG welding power source. And a ratio (Ia / Ib) between a first welding current (Ia) fed from the TIG welding power source and a second welding current (Ib) fed from the MIG welding power source is a predetermined value. By the magnetic force of the repulsive action generated by the first welding current (Ia) flowing through the non-consumable electrode of the preceding TIG and the second welding current (Ib) flowing through the CuSi wire of the subsequent MIG, A TIG arc and a MIG arc that repel each other are generated at a welding start position of the fillet joint portion, and a melt pool is formed by the repelling TIG arc and the MIG arc, and the TIG arc and the MIG arc, Welding is performed from the start position to the end position of the weld line of the fillet joint by composite welding using the one molten pool.

  In order to achieve the above object, a welding apparatus for heat transfer copper fins for metal casks according to the present invention includes an outer surface of a steel inner cylinder that houses an assembly of spent fuel having a radioactive substance, and the inner cylinder. When welding both end surface portions of a predetermined number of copper heat transfer copper fins that are inclinedly arranged at substantially equal intervals between the inner surface of a steel outer tube disposed coaxially on the outer side of the outer surface of the inner tube The inner tube side wide-angle inclined fillet joint formed by abutting one end surface portion of the heat transfer copper fin in the longitudinal direction of the heat transfer copper fin, or the other end surface of the heat transfer copper fin in the longitudinal direction of the inner surface of the outer tube Welded to the outer tube side wide fillet joint part formed by butting the parts, or the fillet joint part formed on both surfaces of the inner cylinder and the outer cylinder by composite welding of the preceding TIG and the subsequent MIG In welding equipment for heat transfer copper fins for metal casks, An integrated TIG-MIG welding torch capable of at least composite welding of the preceding TIG and the subsequent MIG to the weld line of the fillet joint portion to be formed, and Cu-containing CuSi as a consumable electrode on the subsequent MIG side A wire, a seal gas that allows gas to flow from the tip of the TIG-MIG welding torch toward the welded portion of the fillet joint and the vicinity thereof, and the TIG-MIG welding torch at the tip of the arm via an attachment jig And a TIG welding power source for supplying power with the polarity of the non-consumable electrode of the preceding TIG as the negative electrode and the polarity at the fillet joint side as the positive electrode, An MIG welding power source for supplying power and feeding the wire with the polarity of the CuSi wire of the subsequent MIG as the positive electrode and the polarity of the fillet joint side as the negative electrode, Power is supplied from the first welding current (Ia) supplied from the TIG welding power source and the MIG welding power source while the shield gas flows out from the tip of the TIG-MIG welding torch at the start position of the weld line of the part The ratio (Ia / Ib) to the second welding current (Ib) is output within a predetermined range, and the first welding current (Ia) that flows through the non-consumable electrode of the preceding TIG and the consumable wire of the subsequent MIG. The TIG arc and MIG arc that repel each other are generated at the welding start position of the fillet joint by the repulsive magnetic force generated by the second welding current (Ib), and the TIG arc and MIG that repel each other are generated. One melt pool is formed by an arc, and the weld line start position of the fillet joint is determined by composite welding using the TIG arc, the MIG arc, and the one melt pool. It is characterized by welding to the end position.

  According to the present invention, it is excellent in weldability of a dissimilar joint between copper and steel, has a sufficient size, can secure a heat conduction cross-sectional area effective for throat thickness and heat removal, and has no defects such as cracks. A good weld bead and weld cross section can be obtained, and the heat removal performance can be improved and the manufacturing cost can be reduced.

It is a perspective view which shows the structure of the metal cask with a heat-transfer copper fin concerning Example 1 of this invention. It is a fragmentary perspective view which shows the joint welding structure which expanded the A section in FIG. It is a flowchart which shows the outline | summary of the procedure of the welding method of the heat transfer copper fin for metal casks concerning Example 1 of this invention. It is a fragmentary perspective view which shows the shape of the fillet joint part of the inner cylinder outer surface and the end surface part of a heat-transfer copper fin in the metal cask with a heat-transfer copper fin concerning Example 1 of this invention. It is a fragmentary perspective view which shows the shape of the welding part welded to the fillet joint part by the side of the inner cylinder shown in FIG. It is a fragmentary perspective view which shows the shape of the fillet joint part which should be welded with the outer cylinder outer surface and the other end surface part of a heat-transfer copper fin in the metal cask with a heat-transfer copper fin concerning Example 1 of this invention. It is a fragmentary perspective view which shows the shape of the welding part welded to the fillet joint part by the side of the outer cylinder shown in FIG. It is a figure before forming a molten pool with a TIG arc and a MIG arc, showing a schematic structure and a torch arrangement of an integral structure TIG-MIG welding torch according to Example 1 of the present invention. It is a figure which shows the state which formed the molten pool by the TIG arc and the MIG arc from the state of FIG. It is a perspective view which shows schematic structure and torch arrangement | positioning of the MIG welding torch concerning Example 2 of this invention. It is a figure which shows the end surface shape and torch arrangement | positioning of the heat-transfer copper fin in MIT welding concerning Example 2 of this invention. It is a figure which shows the end surface shape and torch arrangement | positioning of a heat-transfer copper fin in the composite welding of the preceding TIG and subsequent MIG concerning Example 1 of this invention. It is a welding apparatus of the heat transfer copper fin for metal casks concerning Example 3 of this invention, and is a front view which shows the structure which arrange | positioned the TIG-MIG welding torch and the guide roller at the front-end | tip part of a long arm. It is a left view of the structure shown in FIG. It is a characteristic view which shows the relationship between the wire feed speed concerning this invention, a wire welding cross-sectional area, and a throat thickness. It is a characteristic view which shows the relationship between the shift amount of the torch position in MIG welding of the end surface flat surface joint of a copper plate concerning this invention, and an end surface inclined surface joint, and the throat thickness and bead width of a welding part. It is a figure which shows the weld bead external appearance of the end face flat surface joint, and a weld cross-section photograph when changing the shift amount S2 (the second distance S2) of the torch position (wire position) according to the present invention. It is a characteristic view which shows the relationship between the penetration depth when the CuSi wire is directly welded to the carbon steel surface according to the present invention and the dilution rate on the steel side. It is a characteristic view which shows the quality evaluation result and appropriate condition area | region of a weld part when changing the gap of the fillet joint part concerning this invention, and the amount of shifts of a torch position, and performing the TIG-MIG composite welding test. It is a figure which shows the typical welding cross-section photograph of the welded part which carried out TIG-MIG compound welding concerning this invention.

  Hereinafter, based on the illustrated embodiment, a welding method for a heat transfer copper fin for a metal cask of the present invention and its welding apparatus will be described. In each figure, the same symbols are used for the same components.

  FIG. 1 shows a structure of a metal cask with a heat transfer copper fin according to the present embodiment, and FIG. 2 shows a welded structure in which a portion A in FIG. 1 is enlarged.

  In the figure, an inner cylinder 1 is a container for storing an assembly of a plurality of spent fuels (not shown) having radioactive materials therein, and made of steel such as carbon steel having high strength. It has been. On the outer side of the inner cylinder 1, a steel outer cylinder 2 made of the same material as the inner cylinder 1 is arranged coaxially so as to surround the inner cylinder 1. Between the outer surface of the inner cylinder 1 and the inner surface of the outer cylinder 2, dozens of heat transfer copper fins 3 are inclined and arranged at substantially equal intervals in the circumferential longitudinal direction (the predetermined number is N). Yes.

  These N heat transfer copper fins 3 are made of a copper plate made of copper such as pure copper having a high thermal conductivity. By using the copper heat transfer copper fins 3, collapse occurs from the spent fuel assembly. While the heat removal performance for releasing heat to the outside of the inner cylinder 1 and the outer cylinder 2 can be enhanced, it can also contribute to weight reduction and cost reduction. Further, the strength and rigidity of the entire metal cask are determined by a high-strength steel thick inner and outer cylinders 1 and 2 and a plurality of lids (not shown) for sealing the inner and outer cylinders 1 and 2. , Well secured.

  As shown in FIG. 2, an inner welded portion (weld bead and its weld cross section) welded by each fillet joint portion 5 on the inner cylinder 1 side is provided on each end surface portion of the N heat transfer copper fins 3. ) 7 is formed, and an outer welded portion 10 (weld bead and its weld cross section) welded by each fillet joint portion 8 on the outer tube 2 side is formed on each other end surface portion. Yes. The inner welded portion 7 and the outer welded portion 10 of the heat transfer copper fin 3 are not particularly required in strength, but it is necessary to ensure high reliability due to the nature of the material to be stored and stored.

  The angle θ1 between the inner cylinder 1 and the heat transfer copper fin 3 of each fillet joint portion 5 and 8 of the N heat transfer copper fins 3 to be welded, and the outer cylinder 2 and the heat transfer copper fin 3 is determined by the inner cylinder. 1 and the inner surface of the outer tube 2 or both surfaces of the inner tube 1 and the outer tube 2 are inclined at a wide angle in a range of θ1 = 120 degrees ± 15 degrees (105 ≦ θ1 ≦ 135 degrees). .

  Each space 4 adjacent to the N heat transfer copper fins 3 is a place where a resin (not shown) such as a resin material is filled and arranged. These resins are substances that shield radiation emitted from the assembly of spent fuel in a normal line, and after welding, the resin is placed in each space along the inclined surface of the N heat transfer copper fins 3. 4 is filled in each. By arranging the heat transfer copper fins 3 to be inclined at a wide angle, workability during welding is facilitated, and radiation is shielded by the inclined arrangement of the resin filled along the inclined surfaces of the heat transfer copper fins 3. Performance can be increased.

  A method for welding both end portions of the heat transfer copper fin 3 in this embodiment to both surfaces of the inner cylinder 1 and the outer cylinder 2 will be described below.

  FIG. 3 is a flowchart showing an embodiment of a welding procedure outline of the heat transfer copper fin for metal cask according to the present embodiment.

  In this figure, in the welding procedure 100 for the heat transfer copper fins 3, a wire weld cross-sectional area determination step 102 for determining the wire weld cross-sectional area Aw before welding, and one end face of a predetermined number (N) of heat transfer copper fins 3. The inner tube 1 side is welded to the fillet joint portion 5 after forming the fillet joint portion 5 at N locations (5-1, 5-2... The first welding step 103, the repeated welding step 105 for welding N points on the inner cylinder 1 side, the repeated welding step 106 for welding and inspection in a small number on the inner cylinder 1 side, and the welding quality on the inner cylinder 1 side. After completion of the inspection steps 107 and 117, the other end face portions of the N heat transfer copper fins 3 are respectively butted against the outer cylinder 2 side, and the fillet joint portions 8 are arranged at N locations (8-1, 8-2,... 8-N) After that, the second welding step 110 on the outer cylinder 2 side to be welded to the fillet joint portion 8, and N locations on the outer cylinder 2 side are melted. Repeating welding process 112 for contact, welding in a small number of units on the outer cylinder 2 side, and repeated welding process 113 for inspection are sequentially performed.

  In the repeated welding process 105 for welding N points on the inner cylinder 1 side and the repeated welding process 112 for welding N points on the outer cylinder 2 side, welding is repeated one by one on the fillet joint portions 5 and 8 formed at the N positions (continuous). By welding), the temporary assembly work and welding work of the fillet joint portions 5 and 8 can be performed efficiently. On the other hand, it repeats welding and inspection by dividing into a small number of units (about 1 to 5 places). Repeating welding and inspection in the minor unit on the inner cylinder 1 side. Welding and inspection in the minor unit on the outer cylinder 2 side. In the repeated welding step 113, the fillet joint portions 5-1, 5-2,..., 5-N, 8-1, 8-2,. Efficiently perform both welding and inspection operations by repeating both welding and inspection operations so that welding is performed by dividing into about 1 to 5 locations and the welded portion after the welding is inspected. This can be done and the quality of the weld can be verified immediately after welding.

  In this way, by selecting one of two types of operations (continuous welding or repetition of welding and inspection), it is possible to improve work efficiency with priority on welding or improvement in welding quality with priority on inspection.

  Next, after the end of the first welding process 103 on the inner cylinder 1 side and the repeated welding process 105 of N places on the inner cylinder 1 side, or the first welding process 103 on the inner cylinder 1 side, the inner cylinder 1 side After the completion of the repeated welding process 105 for welding N places, the second welding process 110 for the outer cylinder 2 side, and the repeated welding process 112 for welding N places on the outer cylinder 2 side, inspection of the welding quality on the inner cylinder 1 side is completed. In step 107 and the welding quality inspection step 114 on the outer cylinder 2 side, the quality of each welded portion is inspected, and a repair welding step 109 for repairing the welded portion that has failed (steps 108 and 115) in the inspection. , 116 is performed.

  Further, in both the welding process and the inspection process 117 for welding quality on the inner cylinder 1 side and the welding quality inspection process 120 on the outer cylinder 2 side when both welding and inspection operations are repeated, a weld bead is satisfactorily formed in the corresponding welded portion. Whether or not there are defects such as cracks and undercuts, and whether or not the throat thickness L, the penetration depth c, or the like is satisfied. When the inner cylinder 1 side welding quality inspection step 117 and the outer cylinder 2 side welding quality inspection step 120 fail (steps 118 and 121), the rejected welded portion is repaired and welded step 119. , 122 to repair.

  First, in the wire welding cross-sectional area determination step 102 performed before welding, the throat thickness L of the inner welded portion 7 to be formed on the predetermined fillet joint portion 5 is equal to or greater than the plate thickness T1 of the heat transfer copper fin 3 (L ≧ T1). ), The wire welding cross-sectional area Aw is calculated and determined from the wire feeding speed Wf or the wire feeding speed Wf, the wire diameter d, and the predetermined welding speed V.

  The throat thickness L of the inner welded portion 7 is the minimum distance from the melted bottom portion on the heat transfer copper fin 3 side to the weld bead surface, as shown in the wire welding cross-sectional area determining step 102 in FIG. . Moreover, the inner side welding part 7 of the fillet joint part 5 illustrated in the place of the wire welding sectional area determination step 102 is formed by welding one end face part of the heat transfer copper fin 3 to the outer surface of the inner cylinder 1. Although assumed and drawn, it is also assumed that the other end surface portion of the heat transfer copper fin 3 is welded to the inner surface of the outer cylinder 2 to form the outer welded portion 10, and the welded structure shown in FIG. Since it is the same, it is omitted.

  Next, in the first welding step 103 on the inner cylinder 1 side, as shown in FIG. 4, each end surface portion on one side of a predetermined number (N) of heat transfer copper fins 3 on the outer surface of the steel inner cylinder 1. To form the wide-angle fillet joint portions 5-1, 5-2,..., 5-N at substantially equal intervals. In FIG. 4, only two heat transfer copper fins 3 are illustrated and other portions are omitted, but a predetermined number of heat transfer copper fins 3 to be welded are arranged in the circumferential direction of the outer surface of the inner cylinder 1. Are inclined at substantially equal intervals.

  In the first welding step 103 on the inner cylinder 1 side, the outer cylinder 2 is not deployed, and the heat transfer copper fins 3 are inclinedly disposed on the outer surface of the inner cylinder 1 to form a wide-angle fillet joint 5- By forming 1, 5-2... 5-N, the temporary assembly work of the heat transfer copper fin 3 before the main welding and the fillet joint portions 5-1, 5-2. A welding operation or the like can be easily performed.

  In the first welding process 103 on the inner cylinder 1 side, as shown in FIGS. 3 to 5, a predetermined number (N) of heat transfer copper fins 3 are attached to the outer surface of the inner cylinder 1 to fillet joints. After forming the portion 5 at N locations, welding at N locations on the inner cylinder 1 side that is repeatedly welded (continuous welding) one pass at a time to the N fillet joint portions 5-1, 5-2. , 5-2, 5-N are divided in advance into about 1 to 5 places, and the divided 1 to 5 fillet joint parts are divided. 5-1, 5-2, 5-3, 5-4, 5-5 are welded and the welded portion is repeatedly inspected. It is divided into a welding process 106 for repeated welding and inspection.

  In the repeated welding process 105 of N places on the inner cylinder 1 side, the welding start position from each welding start position of the N fillet joint portions 5-1, 5-2,. For each of the welding lines up to (dotted lines 6-1, 6-2... 6-N marked on the lower surface of the heat transfer copper fin 3), CuSi wires containing silicon are used, and the preceding TIG and subsequent MIG Welding is performed one pass at a time by composite welding or MIG welding.

  In the repeated welding process 105 at the N locations on the inner cylinder 1 side, for example, the joint to be welded (both the inner cylinder 1 and the heat transfer copper fin 3) side is rotated and moved by a rotary drive device or the like to be welded. After changing the position of the weld line 6-1 of the meat joint portion 5-1 in the vertical direction, the integrally structured TIG-MIG welding torch or MIG welding torch is positioned on the welding line 6-1 in a downward attitude. The weld line in the case where both end portions of the heat transfer copper fin 3 are flat surfaces is a position where the wire position or torch position (including electrode position) is shifted from the end surface portion to the surface side of the heat transfer copper fin 3 by a predetermined distance. The shift amount S1 (first distance S1) is preferably set in the range of S1 = 0 to 4 mm. A single-pass welding is performed on the welded torch 6-1 from the welding start position to the end position of the TIG-MIG welding torch or the MIG welding torch having a downward-facing structure, and the weld bead and the weld cross section 7-1. It is good to form.

  Thus, by shifting the wire position or torch position to the heat transfer copper fin 3 side and welding, the heat melting of the heat transfer copper fin 3 is promoted and the penetration depth on the steel side is suppressed. The throat thickness L having a sufficient size and a heat conduction cross-sectional area effective for heat removal can be reliably ensured, and a shallow penetration weld bead and weld cross section can be obtained.

  When the one-pass welding of the welding line 6-1 is completed, the welding torch is moved around, and in the welding of the next welding line 6-2, the joint side is rotated again, and the corresponding welding line 6-2 is moved vertically. After changing the posture in the direction, the welding torch that has been moved to avoid is moved along the welding line 6-2 to perform positioning in a downward posture. One-pass welding may be performed while the welding torch travels along the welding line 6-2.

  In this way, the operation of changing the orientation of the weld line of the corresponding fillet joint portion 5, the operation of positioning the welding torch on the weld line, the operation of performing one-pass welding on the weld line while running the welding torch, 1 pass By performing a series of repetitive operations such as an operation for avoiding the welding torch after the welding operation, the predetermined number (N) of the fillet joint portions 5 of the weld lines 6-1, 6-2. A weld bead and weld cross sections 7-1, 7-2... 7-N can be formed, respectively.

  The composite welding of the preceding TIG and the succeeding MIG, the MIG welding, the welding test result, and the like will be described later using another example (FIGS. 8 to 21).

  On the other hand, the welding operation is the same in the welding process 106 of the welding and inspection in the small number unit on the inner cylinder 1 side that repeats the inspection of the inner cylinder 1 side (1-5 locations) and the inspection of the welded portion. As described above, a weld bead is formed by welding a single-pass TIG-MIG welding torch (or MIG welding torch) in a downward posture along the welding line 6-1 from the welding start position to the end position. And it is good to form the welding cross-section part 7-1. After the welding, the welding quality is inspected in the welding quality inspection process 117 on the inner cylinder 1 side. If the welding quality inspection fails, the rejected welded portion is repaired in the repair welding process 119. I am trying to repair it.

  By using CuSi wire to perform composite welding of preceding TIG and subsequent MIG or MIG welding, copper, steel, and Si can be mixed together in a state where they can be dissolved even in the case of dissimilar material welding of copper and steel. As a result, it is possible to form a good weld bead and weld cross section (welded part) without cracks. Although it is possible to use pure copper Cu wire with high thermal conductivity, in the case of pure copper Cu wire, welding is performed for dissimilar material welding of copper and steel compared to CuSi wire containing silicon. This was not adopted in the welding method of the present example because the weldability and the welding quality were inferior and the cracking sensitivity was high.

  Moreover, as shown in FIGS. 3-5, the weld bead of each fillet joint part 5-1, 5-2 ... 5-N welded, and weld cross-section part 7-1, 7-2. .. 7-N, at least the throat thickness L of the welded portion is formed to be equal to or greater than the plate thickness T1 (L ≧ T1) of the heat transfer copper fin 3. Further, the penetration depth c on the inner cylinder 1 side is formed to be 0.05 mm or more and 6 mm or less (0.05 ≦ c ≦ 6 mm) (this penetration depth c will be described later).

As a result, it is possible to reliably secure a throat thickness L having a sufficient size and a heat conduction cross-sectional area effective for heat removal at the welded portion of each heat transfer copper fin 3 on the inner cylinder 1 side, and defects such as cracks. It is possible to obtain a weld bead and a welded cross-section with good quality. Moreover, it can contribute to improvement of heat removal performance and reduction of manufacturing cost. Furthermore, also about the tensile strength of a weld part, the intensity | strength of 100 N / mm < ² > or more can be obtained reliably.

  If the throat thickness L described above is too smaller than the plate thickness T1 of the heat transfer copper fin 3, for example, it is necessary to conduct heat from the inner cylinder 1 side to the heat transfer copper fin 3 side via the inner welded portion 7. As a result, the heat conduction cross-sectional area is reduced, which hinders improvement of heat removal performance. Therefore, the throat thickness L of the welded portion is formed to be equal to or greater than the plate thickness T1 of the heat transfer copper fin 3 (L ≧ T1). In addition, if the penetration depth c on the inner cylinder 1 side is too deep, the melting ratio (dilution ratio) of the steel with respect to the cross-sectional area of the welded portion increases, so that the thermal conductivity of the welded portion decreases and cracking susceptibility increases. It tends to be expensive. If the penetration depth c is too shallow, the tensile strength tends to decrease due to insufficient bonding with the steel side. Therefore, the penetration depth c on the inner cylinder 1 side is formed to be 0.05 mm or more and 6 mm or less (0.05 ≦ c ≦ 6 mm).

  In the inspection step 107 of the welding quality on the inner cylinder 1 side after the repeated welding on the inner cylinder 1 side is completed, whether or not the weld bead is formed well in each welded portion of the inner cylinder 1, cracks, undercuts, etc. The welding quality is inspected and confirmed, such as whether or not there is a defect, whether or not the throat thickness L, the penetration depth c, and the like are satisfied. If it is acceptable (process 108), the process proceeds to the second welding process 110 on the outer cylinder 2 side, which is the next process. Repair welding. It should be noted that the inspection process 107 for the welding quality on the inner cylinder 1 side is omitted, and the inspection process 107 for the welding quality on the inner cylinder 1 side is carried out after the welding operation for both the inner cylinder 1 and the outer cylinder 2 is completed. You can also

  Next, in the second welding process 110 on the outer cylinder 2 side, the first welding process 103 on the inner cylinder 1 side, the repeated welding process 105 for welding N locations on the inner cylinder 1 side, and the minor unit on the inner cylinder 1 side. After the end of the repeated welding process 106 and the inspection process 107 and 117 on the inner cylinder 1 side, the outer circumference of the heat transfer copper fin 3 welded to the inner cylinder 1 side as shown in FIG. An integral cylindrical outer tube 2 is arranged on the side, and the other end face portions of the predetermined number (N) of heat transfer copper fins 3 are butted to each wide-angle fillet joint portion 8-1, 8-2 to 8-N are formed at substantially equal intervals.

  In FIG. 6, as in FIG. 4, only two heat transfer copper fins 3 are shown and the other portions are omitted, but a predetermined number (N) of heat transfer copper fins 3 to be welded are shown. The inner cylinder 1 and the outer cylinder 2 are disposed at substantially equal intervals, and the weld beads and weld cross sections 7-1, 7-2,. It is already formed, and the posture on the joint side is reversed and illustrated.

  Further, in the second welding step 110 on the outer cylinder 2 side, as shown in FIGS. 3, 6 and 7, N fillet joints are formed on the outer cylinder 2 side, and then the N fillets are formed. Repetitive welding process 112 of welding at N places on the outer cylinder 2 side that repeatedly welds (continuous welding) one pass at a time to each of the joint portions 8-1, 8-2. Weld each joint to joints 8-1, 8-2 ... 8-5 and repeat both welding and inspection so as to inspect the welded part after welding. It is divided into a welding process 113 for repeated welding and inspection.

  In the repeated welding step 112 for welding N places on the outer cylinder 2 side, as in the repeated welding process 105 for welding N places on the inner cylinder 1 side, N fillet joints 8 to be welded for each pass are provided. -1,8-2 ... 8-N welding lines from the welding start position to the end position (dotted lines 9-1, 9-2 ... 9- marked on the lower surface of the heat transfer copper fin 3) For N), a CuSi wire containing silicon is used, and welding is sequentially performed one pass at a time by composite welding of the preceding TIG and the subsequent MIG or MIG welding.

  As in the case of welding of the inner cylinder 1, even in the case of welding on the outer cylinder 2, the joint to be welded (the inner cylinder 1, the outer cylinder 2, and the heat transfer copper fin 3) is rotated and moved by a rotary drive device or the like. Then, after changing the posture of the weld line 9-1 of the fillet joint part 8-1 to be welded in the vertical direction, the TIG-MIG welding torch or the MIG welding torch of the integral structure is directed downward on the welding line 9-1. Position with posture.

  As described above, the welding line in the case where the both end surface portions of the heat transfer copper fin 3 are flat surfaces has a wire position or a torch position (including electrode position) from the end surface portion to the surface side of the heat transfer copper fin 3 by a predetermined distance. The shifted position S1 is preferably set in the range of S1 = 0 to 4 mm. The weld bead and the weld cross-section 10 are welded by one pass while the TIG-MIG welding torch or the MIG welding torch having the downward posture is moved along the welding line 9-1 from the welding start position to the end position. −1 may be formed.

  Thus, by shifting the wire position or torch position to the heat transfer copper fin 3 side and welding, the heat melting of the heat transfer copper fin 3 is promoted and the penetration depth on the steel side is suppressed. The throat thickness L having a sufficient size and a heat conduction cross-sectional area effective for heat removal can be reliably ensured, and a shallow penetration weld bead and weld cross section can be obtained.

  When the one-pass welding of the welding line 9-1 is completed, the welding torch is moved around to avoid the welding of the next welding line 9-2 and the welding of the subsequent welding line, as described above. Operation to change the position of the weld line of the fillet joint, operation to position the welding torch on the weld line, operation to perform 1-pass welding on the weld line while running the welding torch, avoid welding torch after 1-pass welding operation By performing a series of repetitive operations such as an operation, a weld bead and a welded cross-sectional portion 10 are respectively connected to the weld lines 9-1, 9-2,... 9-N of a predetermined number (N) of fillet joint portions. -1, 10-2... 10-N can be formed.

  On the other hand, even in the repeated welding step 113 of welding and inspection on the outer cylinder 2 side, which repeats welding (2 to 5 places) on the outer cylinder 2 side and inspection of the welded portion, in the case of the inner cylinder 1 side, Similarly, as described above, the one-pass welding is performed while the TIG-MIG welding torch or the MIG welding torch having the downward structure is moved along the welding line 9-1 from the welding start position to the end position. Then, it is preferable to form the weld bead and the weld cross section 10-1. After the welding, an inspection process 120 for welding quality on the outer cylinder 2 side is performed, and when the inspection process 120 for welding quality on the outer cylinder 2 side fails, the rejected welded portion is repaired in the repair welding process 122. I am trying to repair it.

  Moreover, as shown in FIG.3, FIG6 and FIG.7, the weld bead and weld cross-section part 10 which are the weld parts of each fillet joint part 8-1, 8-2, ... 8-N welded. -1, 10-2... 10-N, at least the throat thickness L of the weld is formed to be equal to or greater than the plate thickness T1 of the heat transfer copper fin 3 (L ≧ T1). The penetration depth c on the outer cylinder 2 side is also set to 0.05 mm or more and 6 mm or less (0.05 ≦ c ≦ 6 mm).

Thus, as described above, as in the case of the inner cylinder 1 side, the welded portion of each heat transfer copper fin 3 on the outer cylinder 2 side has a sufficient size for the throat thickness L and heat effective for heat removal. It is possible to obtain a weld bead having a good quality and a weld cross section having a good quality without a defect such as a crack, while ensuring a conductive cross sectional area. Moreover, it can contribute to improvement of heat removal performance and reduction of manufacturing cost. Furthermore, also about the tensile strength of a weld part, the intensity | strength of 100 N / mm < ² > or more can be obtained reliably.

  In the inspection process 114 of the welding quality on the outer tube 2 side after the repeated welding on the outer tube 2 side is completed, the weld bead is satisfactorily formed in each welded portion on the outer tube 2 side, similarly to the welding inspection on the inner tube 1 side. Inspection / confirmation of the welding quality, such as whether it is formed, whether there is a defect such as a crack or undercut, whether it satisfies the throat thickness L, penetration depth c, etc. If it is acceptable (step 115), the process proceeds to the step of the next process 125. If there is a rejected welded part, the process proceeds to the repair welding process 116, and repaired welding is performed on the rejected welded part and the vicinity.

  FIG. 8 and FIG. 9 show an example of a schematic configuration and an arrangement of the torch of an integrally structured TIG-MIG welding torch according to the present embodiment.

  As shown in FIG. 8, in the TIG-MIG welding torch 11 having an integral structure, a non-consumable electrode 13 such as tungsten, and a first shield gas 14 is directed toward the tip and the welded portion of the non-consumable electrode 13. A TIG unit 12 having a first gas passage (not shown) that flows out, a consumable wire 18 such as a CuSi wire, a wire passage (not shown) through which the consumable wire 18 is inserted, and a tip portion of the consumable wire 18 And the MIG unit 17 provided with the 2nd gas channel etc. which flow out the 2nd shield gas 19 toward a welding part is arranged.

  The first and second shield gases 14 and 19 can change the type and composition of the gas, but here, a mixed gas of Ar gas and He gas is used as the shield gas. By using a mixed gas of Ar gas and He gas for welding copper and steel, compared to pure Ar gas, the potential gradient is high, weldability and wettability are excellent, and the quality is good. It becomes easy to obtain a weld. Although not shown, a water channel for cooling the TIG-MIG welding torch 11 with circulating water is also provided.

  The TIG-MIG welding torch 11 has a long arm 31 that can travel and move with respect to the weld line 6-1 of the fillet joint portion 5-1 between the steel inner cylinder 1 and the copper heat transfer copper fin 3. Attached to the distal end in a substantially downward position via a mounting jig (not shown), or attached to the distal end of the long arm 31 via a mounting jig and a biaxial drive table (not shown) that can move left and right and up and down. It is attached and arranged in the direction of the weld line 6-1.

  Further, an articulated movable welding robot is used instead of the long arm 31 that can be moved and moved, and the TIG-MIG welding torch 11 is arranged (attached) to the wrist of the welding robot, and the TIG-MIG welding torch is arranged. While moving 11, the welding of the preceding TIG and the subsequent MIG may be performed from the start position to the end position of the weld line of the fillet joint.

  Furthermore, the TIG unit 12 on the non-consumable electrode 13 side of the preceding TIG is inclined at a receding angle −α1 in the direction opposite to the welding progress direction, and the MIG unit 17 on the consumable wire 18 side of the subsequent MIG is welded. It is inclined and arranged with a forward angle + α2 in the direction. The receding angle -α1 on the preceding TIG side is preferably in the range of 0 to 45 degrees. It is more preferable to arrange it in the range of 15 to 30 degrees. The forward angle + α2 on the other subsequent MIG side is preferably in the range of 15 to 45 degrees. It is more preferable to arrange it in the range of 15 to 30 degrees.

  Further, the distance interval f1 between the electrodes from the position where the extension line of the tip of the non-consumable electrode 13 intersects the weld line 6-1 of the joint base material to the tip of the consumable wire 18 is in the range of 3 to 9 mm. Good. It is even better if it is preferably placed in the range of 4-7 mm. The electrode height f2 from the weld line 6-1 of the joint base material to the tip of the non-consumable electrode 13 is preferably in the range of 3 to 9 mm. It is even better if it is preferably placed in the range of 4-7 mm.

  In this way, by arranging the TIG-MIG welding torch 11 and running and welding on the welding line, it becomes possible to stably perform composite welding of the preceding TIG and the subsequent MIG.

  If the receding angle −α1 of the TIG unit 12 and the advancing angle + α2 of the MIG unit 17 are too smaller than 15 degrees, for example, the distance interval f1 between the non-consumable electrode 13 and the consumable wire 18 can be brought close to a predetermined range. In addition, the shape of one molten pool 24 formed by the TIG arc 22 and the MIG arc 23 tends to be elongated and unstable. On the other hand, if the receding angle −α1 and the advancing angle + α2 are too larger than the above-described angle range, the droplets of the consumable wire 18 melted by the MIG arc 23 are likely to be spattered and scattered in the direction of the preceding TIG. May adhere to the non-consumable electrode 13 on the preceding TIG side and damage the non-consumable electrode 13, and the gas shielding property is likely to deteriorate, which is not preferable. Therefore, the receding angle −α1 on the preceding TIG side is preferably in the range of 0 to 45 degrees, and the advancing angle + α2 on the subsequent MIG side is preferably in the range of 15 to 45 degrees.

  On the other hand, if the value of the distance interval f1 between the non-consumable electrode 13 and the consumable wire 18 is too smaller than 3 mm, for example, the TIG arc 22 and the MIG arc 23 are too close and spatter generated from the consumable wire 18 on the subsequent MIG side. May adhere to the non-consumable electrode 13 on the preceding TIG side and damage the non-consumable electrode 13, and the behavior of the TIG arc 22 and the MIG arc 23 is likely to be unstable. On the other hand, if the distance interval f1 between the non-consumable electrode 13 and the consumable wire 18 is too larger than 9 mm, the shape of one molten pool 24 formed by the TIG arc 22 and the MIG arc 23 tends to be elongated and unstable, and the desired distance A weld bead and a weld cross section may not be obtained. Accordingly, the distance interval f1 between the electrodes from the position where the extension line of the tip of the non-consumable electrode 13 intersects the weld line 6-1 of the joint base material to the tip of the consumable wire 18 is in the range of 3 to 9 mm. Good.

  Furthermore, if the electrode height f2 from the weld line 6-1 of the joint base material to the tip of the non-consumable electrode 13 is too smaller than 3 mm, for example, a decrease in arc voltage and a decrease in heat input associated with the shortening of the TIG arc 22 Insufficient melting may occur, and the tip of the non-consumable electrode 13 is close to the surface of the molten pool 24, so that it is easily affected by changes in behavior of the molten pool 24 and scattered spatter. On the other hand, if the electrode height f2 from the weld line 6-1 of the joint base material to the tip of the non-consumable electrode 13 is too larger than 9 mm, arc destabilization and increased heat input accompanying the extension of the TIG arc 22 The heat transfer copper fins 3 may be melted excessively, which may cause undercutting, and the gas shield property is likely to deteriorate, which is not preferable. Therefore, the electrode height f2 from the weld line 6-1 of the joint base material to the tip of the non-consumable electrode 13 is preferably in the range of 3 to 9 mm.

  As shown in FIG. 9, the TIG welding power source 15 is connected between the non-consumable electrode 13 in the TIG unit 12 and the inner cylinder 1 of the joint base material via power supply cables 16-1 and 16-2. In addition, the TIG arc 22 is generated at the welding location with the polarity on the non-consumable electrode 13 side being the negative electrode (minus) and the polarity on the inner cylinder 1 side being the positive electrode (plus). The other MIG welding power source 20 (including the wire feeding device) is connected between the consumable wire 18 in the MIG unit 17 and the inner cylinder 1 of the joint base material via power supply cables 21-1 and 21-2. In addition, the MIG arc 23 is generated in the vicinity of the rear of the TIG arc 22 with the polarity on the consumable wire 18 side being positive (plus) and the polarity on the inner cylinder 1 side being negative (minus).

  The first welding current Ia flowing through the non-consumable electrode 13 on the preceding TIG side and the second welding current Ib flowing through the consumable wire 18 (CuSi wire) on the subsequent MIG side repel each other. Two matching TIG arcs 22 and MIG arcs 23 form one molten pool 24 and are welded while moving in the welding progress direction 25.

  The ratio (Ia / Ib) between the first welding current Ia flowing through the non-consumable electrode 13 and the second welding current Ib flowing through the consumable wire 18 is set within the range of about 0.8 to 1.2 and output. Good to do. Further, both the first and second welding currents Ia and Ib are preferably fed with direct current to form two arcs of direct current.

  Welding current Ia between direct currents in the range of the ratio of the first welding current Ia flowing through the non-consumable electrode 13 and the second welding current Ib flowing through the consumable wire 18 (Ia / Ib = 0.8 to 1.2). By outputting Ib, the TIG arc 22 and the MIG arc 23 that repel each other are maintained in a state of being substantially deflected downward, and one molten pool 24 can be stably formed. Further, the droplets from the tip of the consumable wire 18 do not scatter and easily transfer into the molten pool 24, and the weld bead and weld cross section 7- having a good weld bead and weld cross section can be obtained. 1 can be obtained.

  When the ratio (Ia / Ib) between the first welding current Ia flowing through the non-consumable electrode 13 and the second welding current Ib flowing through the consumable wire 18 is too small or too large, the TIGs repel each other. Since a large deviation occurs between the arc 22 and the MIG arc 23, the arc behavior on the side with a smaller current becomes unstable due to the influence of the arc force on the side with a larger current, which tends to cause poor welding.

  On the other hand, for example, when the polarity on the TIG side is reversed from the negative electrode (minus) to the positive electrode (plus), the non-consumable electrode 13 such as tungsten is consumed violently due to high temperature overheating during welding, so that the arc behavior is unstable. This tends to cause poor welding and makes it difficult to weld for a long time. In addition, since the TIG arc 22 and the MIG arc 23 are deflected in a mutually attracting direction, droplets of the MIG side consumable wire 18 are welded to the non-consumable electrode 13 on the TIG side, and electrode consumption occurs in a short time. There is also. If the polarity of the other MIG side is reversed from the positive electrode (plus) to the negative electrode (minus), unstable arc behavior and spatter are likely to cause poor welding, making it difficult to weld for a long time. .

  In FIG. 9, for ease of explanation, the TIG arc 22 and the MIG arc 23 and one molten pool 24 are shown on the weld line 6-1 near the center, but the TIG arc 22 and the MIG arc are actually shown. 23 is a welding start position on the weld line 6-1 of the fillet joint portion 5-1 to be welded.

  For example, the joint (inner cylinder 1 and heat transfer copper fin 3) side to be welded is rotated by a rotary drive device or the like, and the welding line 6-1 of the fillet joint portion 5-1 to be welded is oriented in the vertical direction. After the change, the monolithic TIG-MIG welding torch 11 is positioned on the welding line 6-1 in a downward posture. Thereafter, the TIG-MIG welding torch 11 is stopped at the welding start position on the welding line 6-1. While flowing a mixed gas of Ar gas and He gas from both the opening of the TIG unit 12 in the TIG-MIG welding torch 11 and the opening of the MIG unit 17 at and near the welding start position, An electrode negative electrode (minus) TIG arc 22 is generated from the tip of the non-consumable electrode 13 and the first welding current Ia arrives at a steady value or is sent as a consumable wire 18 of the subsequent MIG immediately after a predetermined time. A positive electrode (plus) MIG arc 23 is generated in the vicinity of the rear of the TIG arc 22 from the CuSi wire to be fed, and the second welding current Ib is reached to a steady value to repel each other. The TIG-MIG welding torch immediately after the MIG arc 23 generates one molten pool 24 at the welding start position or after a predetermined time has elapsed. 11 is made to travel to the welding end position of the fillet joint 5-1 while moving one molten pool 24 in the weld line direction.

  By carrying out welding in this way, as described above, the weld 7 having a good weld bead and weld cross section on the weld line 6-1 from the weld start position to the end position of the fillet joint 5-1. −1 can be obtained.

  FIG. 10 shows an example of a schematic configuration and a torch arrangement of a MIG welding torch as Embodiment 2 of the present invention. The example shown in this figure is an example in the case of using the MIG welding torch 26 instead of the TIG-MIG welding torch 11 described above.

  As shown in the figure, when the MIG welding torch 26 is used, the MIG welding is performed between the CuSi wire of the consumable wire 18 and the inner cylinder 1 of the joint base material via the feeding cables 29-1 and 29-2. A power supply 28 is connected. In addition, the MIG welding torch 26 is similar to the above-described TIG-MIG welding torch 11 in that the distal end portion of a long arm (not shown) that can travel and move with respect to the welding line 6-1 to be welded. It is attached to the wrist of an articulated movable welding robot (not shown) in a substantially downward position via an attachment jig (not shown), and is arranged in the direction of the welding line 6-1. Further, the MIG welding torch 26 in the present embodiment is disposed so as to be substantially perpendicular to the welding progress direction or at an advance angle + α3.

  Although the advance angle + α3 is omitted, it is a torch inclination angle corresponding to the inclination angle + α2 of the MIG unit 17 in the TIG-MIG welding torch 11 shown in FIG. 8 and FIG. When the MIG welding torch 26 shown is used, the advance angle + α3 is preferably in the range of 0 to 30 degrees. It is more preferable to arrange it in the range of 0 to 15 degrees. If welding is performed with the advance angle + α3 larger than 30 degrees, the MIG arc is inclined too far forward, so that the droplets of the consumable wire 18 melted by the MIG arc are likely to scatter forward (occurrence of spattering) easily. , Gas shielding properties are also liable to deteriorate, which is not preferable.

  When performing MIG welding, the MIG arc (not shown) of the wire positive electrode (plus) is made while the MIG shield gas 27 made of a mixed gas of Ar gas and He gas is allowed to flow out from the opening at the tip of the MIG welding torch 26. 1) is generated from the welding start position on the weld line 6-1 of the fillet joint 5 and one melt pool is formed by one arc, and then the MIG welding torch 26 is moved while moving in the welding direction. We are trying to weld in the orientation.

  Welding of the wire positive electrode (plus) that supplies DC current with DC MIG arc is also possible, but if pulse MIG arc that repeats high peak current and low current alternately is used, spatter is generated more than DC MIG arc. There is little welding.

  The angle θ1 between one end surface portion of the heat transfer copper fin 3 on the inner tube 1 side to be welded and the fillet joint portion 5 or the other end surface portion of the heat transfer copper fin 3 on the outer tube 2 side and the fillet joint portion 5 is θ1. = 120 ° ± 15 ° (105 ≦ θ1 ≦ 135 °) wide angle inclination (configuration), and both of the heat transfer copper fins 3 formed on both surfaces of the inner cylinder 1 and the outer cylinder 2 The angle θ1 of the fillet joint portion 5 with the end face portion is also preferably arranged within the same range as the above value. Further, the inclination angle θ2 on the other inner cylinder 1 side or outer cylinder 2 side is arranged to be in a range of θ2 = 30 degrees ± 15 degrees (15 ≦ θ2 ≦ 45 degrees) with respect to the horizontal line.

  The joint member (the heat transfer copper fin 3 and the inner cylinder 1 or the heat transfer fin 3 and the outer cylinder 2) is inclined in such an angle range, so that the same applies to the MIG welding torch 26 (TIG-MIG welding torch 11). ) Can be arranged in a substantially vertical downward position, the operability of the welding torch and the like is improved, and preparatory work and welding work before welding can be improved.

  As described with reference to FIGS. 1 and 2, each space 4 divided between the inner cylinder 1 and the outer cylinder 2 and a plurality of (N) heat transfer copper fins 3 contains spent fuel. A substance (resin) that shields radiation emitted from the aggregate in a normal line is filled in a resin filling step that is performed separately. For this reason, as shown in FIGS. 4 to 7 and 10, when the angle θ1 of the fillet joint portion 5 is larger than 135 degrees, radiation can be effectively shielded by the resin filling described above. The plate width of each heat transfer copper fin 3 to be welded between the outer surface of the inner cylinder 1 and the inner surface of the outer cylinder 2 at the time of welding construction must be made large in advance.

  For this reason, the manufacturing cost of the heat transfer copper fins 3 is increased, and at the time of welding the heat transfer copper fins 3 adjacent to each other, a part of the welding torch comes into contact with the adjacent heat transfer copper fins 3 and welding is performed. There is a high possibility that it cannot be done.

  On the other hand, if the angle θ1 of the fillet joint portion 5 is smaller than 105 degrees, the plate width of the heat transfer copper fins 3 can be reduced and welding can be easily performed, but the radiation emitted from the assembly of spent fuel. A part of the amount is expected to be transmitted between the resins (the heat transfer copper fins 3 and the gaps), and it is not preferable because the radiation shielding ability may be reduced due to the leakage of the radiation amount.

  Therefore, by arranging the angle θ1 of the fillet joint portion 5 at a wide-angle inclination in the range of 105 ≦ θ1 ≦ 135 degrees, it is possible to perform welding work and secure the radiation shielding ability.

  Further, the inclination angle θ2 on the inner cylinder 1 side or the outer cylinder 2 side is an angle for disposing the MIG welding torch 26 (the same applies to the TIG-MIG welding torch 11) in a substantially vertical downward posture. For example, when the angle θ1 of the fillet joint 5 is to be reduced, the other inner cylinder 1 side or the outer cylinder 2 side may be changed. When the inclination angle θ2 is changed in the increasing direction, and the angle θ1 of the fillet joint portion 5 is increased, it is preferable to change the inclination angle θ2 in the decreasing direction.

  The integrated TIG-MIG welding torch 11 shown in FIGS. 8 and 9 and the MIG welding torch 26 dedicated to MIG welding shown in FIG. 10 can be moved and moved by a drive device 311 as shown as an example in FIG. Can be attached to the tip of the long arm 31 (or the wrist of a multi-joint movable welding robot) in a substantially downward position via an attachment jig, or can be attached to the tip of the long arm 31 and can be moved left and right and up and down. It is mounted in a substantially downward posture via a two-axis drive table and is arranged in the weld line direction. Moreover, from the welding start position of the weld line of the fillet joint part to be welded for each pass to the copper plate of the heat transfer copper fin 3 and the steel material of the inner cylinder 1 or the outer cylinder 2 and the fillet joint part, to the end position, The traveling operation and welding operation of the integrally structured TIG-MIG welding torch 11 or MIG welding torch 26 are executed in accordance with the traveling command of the long arm 31 by the welding control device 201 and the output commands to the TIG welding power source 15 and the MIG welding power source 20. While performing the composite welding of the preceding TIG and the subsequent MIG or MIG welding, welding is performed from the start position to the end position of the weld line of the fillet joint.

  In this manner, by placing the MIG welding torch 26 or the TIG-MIG welding torch 11 downward on the weld line 6-1 of the fillet joint portion of the joint slope, welding is performed, thereby starting from the start position of the weld line. While being able to weld stably to an end position, it becomes possible to obtain a favorable weld bead and a weld cross section.

  FIGS. 11 and 12 show an example of the shape of both end surfaces of the heat transfer copper fin 3, the joint arrangement, and the torch arrangement in the MIT welding according to the present embodiment or the combined welding of the preceding TIG and the succeeding MIG.

  The shape of both end faces of the heat transfer copper fin 3 (length direction shortening) shown in FIG. 11 is inclined with respect to the surface of the heat transfer copper fin 3 within a range of 30 ° ± 15 ° (end surface inclination angle: 15 ≦ β1 It is an inclined surface shape 38 that is ≦ 45 degrees, and is processed in advance into an inclined surface substantially parallel to the surface of the inner cylinder 1 (or the surface of the outer cylinder 2). This is an example in which the MIG welding torch 26 is arranged on the weld line of the fillet joint portion including the heat transfer copper fin 3 having the inclined surface shape 38.

  On the other hand, the shape of both end surfaces of the heat transfer copper fin 3 shown in FIG. 12 is a flat surface shape 39 of an end surface (corresponding to β1 = 0) having no inclined surface. This is an example in which the TIG-MIG welding torch 11 is disposed on the weld line of another corner joint portion provided with the heat transfer copper fin 3 having the flat surface shape 39.

  In these examples, the non-consumable electrode 13 on the preceding TIG side is mainly illustrated, and the consumable wire 18 on the subsequent MIG side is omitted. When both end surface portions of the heat transfer copper fin 3 have the flat surface shape 39, the processing cost can be reduced as compared with the case of the inclined surface shape 38. The MIG welding torch 26 described in FIG. 11 and the TIG-MIG welding torch 11 described in FIG. 12 can be interchanged and arranged on the weld line of the fillet joint portion to be welded.

  On the other hand, with respect to the joint angle θ1 of the fillet joint 5 between the inner cylinder 1 side (or outer cylinder 2 side) and one end face of the heat transfer copper fin 3, both end faces of the heat transfer copper fin 3 are inclined surface shape 38. The same applies to the case of the flat surface shape 39.

  As described above, the joint angle θ1 of the fillet joint 5 between the inner cylinder 1 side (or the outer cylinder 2 side) and the one end surface portion of the heat transfer copper fin 3 is θ1 = 120 degrees ± 15 degrees (105 ≦ θ1 ≦ 135 degrees) is formed at a wide angle inclination. The inclination angle θ2 on the other inner cylinder 1 side (the same applies to the outer cylinder 2) is arranged in a range of θ2 = 30 degrees ± 15 degrees (15 ≦ θ2 ≦ 45 degrees) with respect to the horizontal line. In addition, since there is no gap G on the bottom surface of the fillet joint portion 5, the position of the MIG welding torch 26 (or TIG-MIG welding torch 11) is shifted to the heat transfer copper fin 3 side. Since the first distance S1 (or the second distance S2) may change, the gap G, the first distance S1, and the second distance S2 are shown in FIG.

  The first distance S1 is the tip of the consumable wire 18 (or the extension line of the non-consumable electrode 13 and the heat transfer copper fin) from the end surface corner b point of the heat transfer copper fin 3 to the position corresponding to the weld line 6. It is the length (distance) obtained by shifting the position of the intersecting point with the three surfaces. The other second distance S2 is the position of the weld line at the upper part where the extension line of the surface of the heat transfer copper fin 3 passes the point b from the point a where it intersects the surface of the inner cylinder 1 (or the surface of the outer cylinder 2). This is the length (distance) to which the consumable wire 18 (or the non-consumable electrode 13) has been shifted.

  Further, there is a correlation between the first distance S1 and the second distance S2, which is expressed by an equation of S2 = S1 + T1 / tan (180−θ1) −T1 × tanβ1 + G / sin (180−θ1). When the value of β1 is 30 ° ± 15 ° as described above, the heat transfer copper fin 3 has the inclined surface shape 38, and S2 when β1 = θ1−90 ° is S2 = S1 + G / sin (180− It can be simplified to the equation of θ1). When the value of β1 is 0 degree, the heat transfer copper fin 3 has a flat surface shape 39, and S2 at that time is S2 = S1 + T1 / tan (180−θ1) + G / sin (180−θ1). The formula can be simplified.

  The TIG-MIG welding torch 11 or the MIG welding torch 26 is set to a substantially downward posture on the weld line at the first distance S1 range position or the second distance S2 range position, and the preceding TIG and the subsequent MIG By welding from the start position to the end position of the fillet joint portion by composite welding or MIG welding, stable welding can be performed from the start position to the end position of the weld line, and a good weld bead and A weld cross section can be obtained.

  13 and 14 show a welding apparatus employed in the first embodiment as the third embodiment of the present invention, and shows an example in which a TIG-MIG welding torch and a guide roller are arranged at the distal end portion of the long arm. is there.

  As shown in the figure, the TIG-MIG welding torch 11 having an integral structure for performing composite welding of the preceding TIG and the succeeding MIG has a long length via mounting jigs 34 and 35 and a biaxial drive table 36 that can move left and right and up and down. It is disposed (attached) at the tip of the arm 31. The biaxial drive table 36 can be driven in the horizontal direction and the vertical direction with respect to the welding line direction, and the biaxial drive table 36 automatically moves the horizontal and vertical positions of the TIG-MIG welding torch 11. be able to.

  Further, the rotationally movable guide roller 32 is located at the right position ahead of the TIG-MIG welding torch 11, is disposed below the long arm 31, and is a heat transfer away from the welding line by a short distance. It is arranged so as to rotate in contact with both surfaces of the surface portion of the copper fin 3 and the surface portion on the inner tube 1 side (or the surface portion on the outer tube 2 side). By the contact rotational movement of the guide roller 32, the TIG-MIG welding torch 11 can be easily traveled and guided in the weld line direction of the fillet joint portion.

  Further, if the welding of the fillet joint portion is small, such as bending of the weld line and deformation due to welding, and accurate positioning in advance, the guide roller 32 can be used without using a measuring device such as a slit light cutting sensor. While the TIG-MIG welding torch 11 travels and guides in the direction of the weld line of the fillet joint by contact rotation, composite welding of the preceding TIG and the subsequent MIG is performed from the start position to the end position of the fillet joint. It is possible to obtain a good weld bead and weld cross section.

  On the other hand, 37 is a shielding plate that shields radiant heat and scattered matter. The TIG-MIG welding torch 11 (or MIG welding torch 26) for welding in the direction of the welding line and the TIG-MIG welding torch 11 (or MIG welding). Between the surface portion of the heat transfer copper fin 3 and the surface portion on the inner tube 1 side or the surface portion on the outer tube 2 side at a position forward of the torch 26) and a short distance from the weld line of the fillet joint. Between the guide roller 32 that can be rotated and moved so as to rotate in contact with both sides, and at the upper position in the direction substantially perpendicular to the welding line, it is arranged below the tip of the long arm 31. Yes.

  By disposing the shielding plate 37, it is possible to shield radiant heat generated during welding by the TIG-MIG welding torch 11 or the MIG welding torch 26, and scattered matter such as spatter and fume. At the same time, the guide roller 32 in the preceding position can be protected at the same time.

  Further, as shown in FIGS. 8 and 11 to 14, the welding apparatus includes at least a TIG-MIG welding torch 11 having an integrated structure capable of composite welding of the preceding TIG and the subsequent MIG, and a consumable wire 18 on the subsequent MIG side. A first seal gas 14 made of a mixed gas of Ar and He that causes a gas to flow out from the tip portion of the TIG-MIG welding torch 11 toward the welded portion of the fillet joint portion and the vicinity thereof. And the second shield gas 19, the long arm 31 to which the TIG-MIG welding torch 11 can be attached to the tip of the arm via the attachment jig 35 and movable in the welding direction, and non-consumable of the preceding TIG The TIG welding power source 15 for supplying power with the polarity of the electrode 13 being negative (minus) and the polarity of the fillet joint side being positive (plus), and the pole of the consumable wire 18 of the other subsequent MIG And a MIG welding power source 20 that performs power feeding and wire feeding with a positive polarity (plus) and a negative polarity (minus) on the fillet joint side.

  With such a welding apparatus, power is supplied from the TIG welding power source 15 while flowing a mixed gas of Ar + He from the tip of the TIG-MIG welding torch 11 at and near the start position of the weld line 6-1 of the fillet joint. The ratio (Ia / Ib) of the first welding current Ia to be performed and the second welding current Ib fed from the MIG welding power source 20 is output in the range of 0.8 to 1.2, and the non-consumable electrode of the preceding TIG The welding of the fillet joint portion is started with two arcs repelling each other by the magnetic force of the repulsive action generated by the first welding current Ia flowing through 13 and the second welding current Ib flowing through the consumable wire 18 of the subsequent MIG. A molten pool 24 is formed by the TIG arc 22 and the MIG arc 23 which are generated at the positions and repel each other, and the combined melting of the TIG arc 22 and the MIG arc 23 and the one molten pool 24 is performed. Accordingly, it will be welding from the start position of the weld line 6-1 of fillet joints to the end position.

  This makes it possible to stably weld and obtain a good weld bead and weld cross section.

  In the embodiment shown in FIG. 13 and FIG. 14, the arrangement example of the TIG-MIG welding torch 11 having an integral structure is described, but the MIG welding torch 26 may be replaced with MIG welding. it can. Further, the TIG-MIG welding torch 11 is arranged at the tip of the long arm 31 via the mounting jigs 34 and 35 and the biaxial drive table 36, but without the biaxial drive table 36 being mounted, -The MIG welding torch 11 can also be arranged at the tip of the long arm 31.

  Further, in this embodiment, the long arm 31 is moved to the right and the welding operation is performed while the TIG-MIG welding torch 11 is moved to the right. However, the long arm 31 is moved to the right. When moving to the left side opposite the guide roller 32, the guide roller 32 is replaced at the leading position, the TIG-MIG welding torch 11 is replaced at the subsequent position, and rotated 180 degrees so as to be the preceding TIG-following MIG. The welding operation can be normally performed while moving in the left direction.

  Further, as described above, the guide roller 32 is moved to the long arm 31 so as to rotate in contact with both the surface portion of the heat transfer copper fin 3 and the surface portion on the inner tube 1 side or the surface portion on the outer tube 2 side. The TIG-MIG welding torch 11 is guided to travel in the direction of the welding line by the contact rotational movement of the guide roller 32, and the preceding TIG, the following MIG, the TIG arc 22, the MIG arc 23, and one molten pool 24. By performing welding from the start position to the end position of the weld line of the fillet joint portion by the composite welding according to, it is possible to stably weld and obtain a good weld bead and weld cross section.

  In the embodiment shown in FIGS. 13 and 14, the TIG-MIG welding torch 11 is disposed on the long arm 31, but an articulated movable welding robot is used instead of the long arm 31. The TIG-MIG welding torch 11 (or MIG welding torch 26) is placed (attached) on the wrist of the welding robot, and the combined welding (or MIG welding) of the preceding TIG and the succeeding MIG is performed while moving the torch. Welding may be performed from the start position to the end position of the weld line of the joint portion.

  Next, the welding test method and results actually conducted by the present inventors will be described.

  First, since there is a high possibility that the first and second distances S1 and S2 that shift the gap G, the torch position, or the wire position of the fillet joint 5 of different materials of copper and steel are changed, it affects the welding quality. In order to confirm the influence and the welding condition tolerance, a welding test was performed to change the gap G and the first distance S1, and the welding quality and the like were evaluated. In addition, the relationship between the wire feed speed, the wire weld cross-sectional area and the throat thickness was investigated. Furthermore, in order to investigate the relationship between the penetration depth on the steel side, dilution rate (melting ratio), cracks, etc., a test was also conducted in which a CuSi wire was directly welded to the steel plate surface.

  In the MIG welding test, a fillet joint of a copper plate (C1020P) having a thickness of 5 mm and a carbon steel plate (SM400A) having a thickness of 16 mm is used. In the TIG-MIG combined welding test, a copper plate (C1020P) having a thickness of 5 mm is used. A fillet joint with a carbon steel plate (SM400A) having a thickness of 50 mm was used. The welding wire used was a 1.2 mm diameter CuSi wire (MG960), and the shielding gas used was a mixed gas of Ar gas and He gas (50 to 70%).

  FIG. 15 shows the relationship between the wire feed speed Wf, the wire weld cross-sectional area Aw and the throat thickness L according to the present invention, and the logical throat thickness L0 (when the cross-sectional area of the wire weld portion is assumed to be an isosceles triangle. (Calculated value without penetration), throat thickness L (measured value with penetration) of the MIG welded part and TIG-MIG composite welded part actually welded, and an example of a photograph of the weld cross section are also shown.

  In the MIG welding test, a pulse current waveform was used, the welding speed was suppressed (204 mm / min), and the wire feed speed Wf was changed from 6 to 9 m / min (welding current 165 to 260 A) for welding. In the TIG-MIG combined welding test, the welding speed is increased to 350 mm / min, and the wire feed speed Wf is increased and increased by 10 to 12 m / min (MIG current 300 to 360 A, TIG current 300 to 360 A). Welded. FIG. 15 shows the result at that time.

  The weld cross section of the copper plate and steel plate is indicated by □ and ■ in the figure because the bead surface has a convex shape (curved shape) and the copper plate side also has a penetration as shown in the photograph of the weld cross section in the figure. The throat thickness L of the weld cross section is larger than the logical throat thickness L0 indicated by ▲ in the figure, and is larger than the thickness (T1 = 5 mm) of the copper plate corresponding to the heat transfer copper fin. Furthermore, in the case of TIG-MIG composite welding, since it is heated and melted by TIG arc and MIG arc, compared with the case of MIG welding, the amount of heat input Q is larger and the melting on the copper side becomes deeper. Even if Aw (indicated by ◯ in the figure) is small, the throat thickness L can be formed larger than the thickness of the copper plate (T1 = 5 mm).

From such test results, if the welding is set to a range of wire welding sectional area Aw of about ^{30~55mm 2 (30 ≦ Aw ≦ 55mm} 2), throat thickness L is equal to 5mm or more and the plate thickness T1 (L ≧ T1 = 5 mm) was determined. Moreover, as a result of estimating the heat input Q (kJ / cm) from the welding current, voltage and welding speed, it was found that the range of about Q = 12 to 35 kJ / cm (12 ≦ Q ≦ 35 kJ / cm) is sufficient. That is, if the wire welding cross-sectional area Aw is too small (30 mm ² or less), it is liable to be insufficient due to insufficient heat input and insufficient melting, or insufficient throat thickness L. Moreover, when there are too many wire welding cross-sectional areas Aw (55 mm < ² > or more), dripping of a molten metal, an undercut, etc. will occur easily.

  FIG. 16 shows the relationship between the shift amount S2 of the torch position, the throat thickness L and the bead width W in the MIG welding of the end face flat joint and the end face inclined joint of the copper plate. In addition, the x mark in the figure indicates welding that is broken from the boundary between the bottom of the molten metal (bottom of the weld metal) and the surface of the steel base material during the cutting of the weld cross section due to insufficient joining and insufficient strength with the steel side. It is data.

  FIG. 17 shows typical weld bead appearances and welds of end face flat surface joints and end face inclined surface joints when MIG welding is performed by changing the shift amount S2 (second distance S2) of the torch position (wire position). The cross-sectional photograph is shown.

  As shown in FIG. 16, the bead width W of the MIG welded portion tends to decrease as the shift amount S2 increases, but the throat thickness L increases to the same extent or slightly, both of which are copper plates. It is formed to be larger than the plate thickness (T1 = 5 mm). In the case of a flat end face joint, since there is an opening at the bottom of the joint (size corresponding to the gap: 2.9 mm), a part of the molten metal flows into the opening during welding. Compared to the case of the inclined surface joint, the throat thickness L is about 0.5 to 1 mm smaller, and the other bead width W is about 1 to 1.4 mm larger. Further, even when the end face inclined surface joint has a gap (G = 0 to 2 mm), the throat thickness L is formed larger than the thickness of the copper plate (T1 = 5 mm).

  The maximum penetration depth c on the steel side is not described in FIG. 16, but as shown in the weld cross-section photograph in FIG. 17, a weld cross-section having a shallow penetration depth c is not obtained in MIG welding. can get. For example, in the case of a flat end face joint, when the shift amount S2 (second distance S2) of the torch position is 0.9 mm ((1) in FIG. 17), it is about 0.37 mm and 4.9 mm ( In FIG. 17 (2)), it was about 0.12 mm. When the shift amount S2 was large 6.9 mm, it broke during cutting and could not be measured, but it was determined that the penetration depth c was almost 0 mm.

  On the other hand, the maximum penetration depth c in the case of the end face inclined surface joint is about 0.15 mm and 3 mm (FIG. 17 (4)) when the shift amount S2 is 0 mm (FIG. 17 (3)). Since it was about 0.10 mm and fractured during cutting when S2 was 5 mm, the penetration depth c was determined to be almost 0 mm, as in the case of the end face flat surface joint.

  From the above results, the appropriate range of shift amount S2 (second distance S2) that can be formed when the throat thickness L of the weld is equal to or greater than the thickness T1 of the copper plate (L ≧ T1 = 5 mm) is the case of the end face flat joint. The range is about S2 = 0.9 to 6 mm, and when converted to the distance S1 (first distance) from the corner portion of the copper end face, the range is S1≈−1.9 to 3.1 mm. In the case of the end face inclined face joint, the range is about S2 = 0 to 4 mm. When converted to the distance S1 (first distance) from the corner of the copper end face, even when the gap G is 0 to 2 mm, S1≈0 to 0. The range is 4 mm. The penetration depth c of these welds is about 0.05 to 0.37 mm, and the lower limit value of the penetration depth c that can be joined is 0.05 mm or more. Note that the test data that was broken (×) during cutting was excluded because of insufficient strength.

  FIG. 18 shows the relationship between the penetration depth when the CuSi wire is directly welded to the carbon steel surface and the dilution rate on the steel side. Both the MIG single welding result and the TIG-MIG composite welding result are shown together. Yes.

  The dilution rate α (%) shown in the figure was calculated by the equation: α = b / (a + b) × 100, where b is the cross-sectional area of the steel side and a + b is the cross-sectional area of the entire weld. The melt cross-sectional area of each weld is drawn from the weld cross-section photograph magnified about 10 times, and the melt cross-sections a and b inside the contour are calculated by the area calculation software, and then the dilution rate α is set. Each was calculated.

  As a result, when the wire feed rate is increased (the MIG current is also increased), the penetration depth c and the dilution rate α tend to increase, and the higher the welding speed, the greater. Further, in the case of TIG-MIG composite welding, the wire feed speed was increased to 12.2 m / min and welding was performed, but no cracks occurred.

  On the other hand, in the case of MIG single welding, the penetration depth c and the dilution rate α are larger than in the case of TIG-MIG composite welding, the penetration depth c is about 7 mm or more, and the dilution rate α is about When it was 50% or more, cracks opened on the surface of the weld bead occurred. For this reason, even in TIG-MIG combined welding, it is estimated that the penetration depth c and the dilution rate α will increase when the wire feed rate is further increased, leading to the occurrence of cracks.

  From these results, the cracking boundary is estimated to be difficult to crack in the region where the steel side dilution rate α is 50% or more and the penetration depth c is about 6 mm or more, and is smaller than these values.

  In the case of MIG welding, since the arc having a pulse waveform that repeats a high peak current and a low base current is generated in the downward direction and welding is performed, the penetration depth increases with increasing arc force and directivity. It is conceivable that c increases.

  On the other hand, in the case of TIG-MIG composite welding, the non-consumable electrode of the preceding TIG and the wire electrode of the subsequent MIG are inclined in the welding direction, and the TIG arc and the MIG arc are deflected in a repulsive direction. Since it is generated and welded in this state, it is considered that the arc force and directivity are suppressed and increase in penetration depth is suppressed as compared with the case of MIG welding. When Cu wire is used instead of CuSi wire and MIG welding is performed on the surface of carbon steel, the cracking susceptibility is increased. For example, cracks opened on the surface of the weld bead in a region where the wire feed speed is about 10 m / min or more. Has been confirmed to occur.

  On the other hand, in dissimilar joint welding of copper and steel, the input heat energy is dispersed to wire melting and copper and steel melting, so that a deep weld penetration is formed without deep penetration. It is considered that cracks are unlikely to occur because it is easy. Also, by welding using CuSi wire containing silicon, even when dissimilar joint welding of copper and steel, copper, steel and Si are mixed properly in a state where they can be dissolved, and there is no crack Good weld beads and weld cross sections can be obtained. If the penetration depth c on the steel side is about 6 mm or less, the problem of cracking can be solved. Therefore, the allowable range of the penetration depth c is preferably 0.05 ≦ c ≦ 6 mm.

  However, since it is expected that the thermal conductivity of the welded portion will decrease as the dilution rate α increases, from the viewpoint of suppressing this, it is preferable to limit the upper limit value of the penetration depth c to 4 mm or less.

  Table 1 shows the welding conditions when the TIG-MIG composite welding test was performed by changing the gap of the fillet joint between the copper plate of the end face flat surface and the carbon steel and the shift amount of the torch position.

  In this welding test, in order to confirm the influence on the welding quality and the welding condition tolerance, the gap G of the fillet joint is changed (G = 0 to 3 mm) and the torch position shift amount S2 (second distance) S2) was changed (S2 = 3 to 9 mm), and a welding test for the preceding TIG and the succeeding MIG was performed in a downward posture. This is a fillet joint of a copper plate (C1020P) with a thickness of 5 mm and a carbon steel plate (SM400A) with a thickness of 50 mm. Each was used (refer to FIGS. 8 to 12 for joint arrangement and torch arrangement).

  Table 2 shows the shape, tensile test and evaluation results of the TIG-MIG composite weld when the welding test is performed under the welding conditions shown in Table 1.

  In Table 2, each value and average value of the throat thickness L, bead vertical height H, penetration depth c, etc. of each welded cross-section sampled from the first half side and the second half side of each weld specimen are shown. In addition, the tensile load and tensile strength of each tensile test piece (welded joint with a width of 40 mm) taken from the central part of the same weld test piece are described, and whether or not the quality standard is satisfied The results of the determination are described respectively.

For example, the throat thickness L is less than 5 mm (No. 9 and No. 13), the penetration depth c exceeds 4 mm (0), and the undercut at the bead toe is 1 mm. Exceeding one (No. 12 No. 12), and having a tensile load Wt of less than 20 kN (100 N / mm ² ) (No. 3 breaks during cutting) are rejected. The test pieces with other numbers satisfy each standard value, and therefore pass. Although not shown in Tables 1 and 2, a welding test is also performed on a joint with a shift amount S2 = 1 mm and a gap G = 0 mm.

  FIG. 19 shows the quality evaluation result and appropriate condition region of the welded part when the TIG-MIG composite welding test is performed by changing the gap of the fillet joint and the shift amount of the torch position. In FIG. 19, the horizontal axis indicates the distance S1 from the corner portion of the copper end surface, and the vertical axis indicates the gap G. In FIG. As described above, the relationship between the distance S1 (first distance S1) from the corner portion of the copper end face and the shift amount S2 (second distance S2) of the torch position is S1 in the case of the end face flat joint. = S2- {T1 / tan (180- [theta] 1) + G / sin (180- [theta] 1)}.

  As shown in the figure, the appropriate condition area (○ mark) that satisfies the quality standards is the area where the throat is insufficient (left mark ◆), the strength is insufficient (right mark ■), and the undercut excessive area (▲ mark). It is in the center part excluding. In the region where the gap G is 3 mm or more, since there is only one test data, it is unknown, but it is thought that there is a possibility of leading to poor welding such as sagging or insufficient throat thickness.

  In addition, there is data that satisfies the quality standard (◯ mark) even in the area of insufficient strength (marked on the right side) and excessively undercut (marked with ▲), but it was excluded from the appropriate condition area. Furthermore, there is data (S1 = -1.9, G = 0 mm) that satisfies the quality standards in the throat thickness deficient region (marked with ♦) on the left side, but was excluded from the proper condition region.

  Therefore, the tolerance for the gap G is about G = 0 to 2 mm or about G = 0 to 3 mm, and the tolerance for the distance S1 from the corner portion of the copper end surface is about S1 = −0.5 to 4 mm. It was judged that. Or it can also be limited to about S1 = 0-4 mm. Further, when replaced with the second distance S2, S2 is approximately 2.5 to 7 mm (or S2 is approximately 3 to 7 mm).

  By performing welding in an appropriate region within such tolerance, it is possible to obtain a good weld bead and weld cross section that satisfy the quality standards.

  FIG. 20 is an example of a typical weld cross-section photograph of a welded portion where TIG-MIG composite welding is performed. FIG. 20 (1) shows a case where the gap G = 0 mm and the shift amount S2 = 5 mm. 2) is a case where the gap G = 2 mm and the shift amount S2 = 5 mm.

  As can be seen from (1) of FIG. 20, when the gap G is 0 mm, the bead surface has a convex shape (curved shape) and tends to be a welded cross-section having a shape that melts to the back side of the copper plate. On the other hand, as can be seen from (2) of FIG. 20, when the gap is about 1 mm or 2 mm, the penetration of the shape penetrating the copper back side by the acceleration of melting of the copper plate and the inflow of the molten metal into the gap At the same time, the penetration depth on the steel side also increases, and the bead surface tends to be a flat weld cross section. In any case, the weld cross section also satisfies the quality standard.

  In addition, in the case of TIG-MIG composite welding, the welding current (TIG current / MIG current) is higher and the welding speed is higher than in the case of MIG single welding, and the fillet joint between copper and steel is used. Since it is heated and melted by two arcs, the penetration on the copper side tends to be a deep weld cross section. In addition, about the crack, it was not recognized from any welding test piece.

  As described above, according to the present invention, the weldability of the dissimilar joint between copper and steel is excellent, the throat thickness L having a sufficient size and a heat conduction cross-sectional area effective for heat removal can be secured, and It is possible to obtain a weld bead and a weld cross section having good quality free from defects such as cracks, and to contribute to an improvement in heat removal performance and a reduction in manufacturing cost.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Inner cylinder, 2 ... Outer cylinder, 3 ... Heat-transfer copper fin, 4 ... Space, 5-1, 5-2 ... 5-N, 8, 8-1, 8-2 ... 8 -N ... fillet joint, 6, 6-1, 6-2 ... 6-N, 9-1, 9-2 ... 9-n ... weld line, 7 ... inner weld, 7-1 , 7-2... 7-N, 10-1, 10-2... 10-N ... weld bead and weld cross section, 10 ... outer weld, 11 ... TIG-MIG welding torch, 12 ... TIG unit , 13 ... non-consumable electrode, 14 ... first shielding gas, 15 ... TIG welding power source, 16-1, 16-2, 21-1, 21-2, 29-1, 29-2 ... feeding cable, 17 ... MIG unit, 18 ... consumable wire, 19 ... second shield gas, 20, 28 ... MIG welding power source, 22 ... TIG arc, 23 ... MIG arc, 24 ... molten pool, 25 ... Direction of contact, 26 ... MIG welding torch, 27 ... Shield gas for MIG, 31 ... Long arm, 32 ... Guide roller, 33, 34, 35 ... Mounting jig, 36 ... Biaxial drive table, 37 ... Shield plate, 38 ... Inclined surface shape, 39 ... Flat surface shape, 100 ... Welding procedure for heat transfer copper fins, 102 ... Wire welding cross-sectional area determining step, 103 ... First welding step on the inner cylinder side, 105 ... N locations on the inner cylinder side Repetitive welding process of 106, welding of a small number of units on the inner cylinder side and repeated welding process of inspection, 107, 117 ... inspection process of welding quality on the inner cylinder side, 109, 116, 119, 122 ... repair welding process, 110: second welding process on the outer cylinder side, 112: repeated welding process for welding N points on the outer cylinder side, 113: repeated welding process for minority unit welding and inspection on the outer cylinder side, 114, 120 ... outer cylinder Side welding quality Inspection step, 201 ... welding control apparatus, 311 ... driving apparatus.

Claims (15)

Inclined deployment at substantially equal intervals between the outer surface of the steel inner cylinder that houses the assembly of spent fuel containing radioactive material and the inner surface of the steel outer cylinder that is coaxially disposed outside the inner cylinder A wide angle on the inner tube side formed by abutting one end surface portion of the heat transfer copper fin in the longitudinal direction of the outer surface of the inner tube when welding both end surface portions of the predetermined number of copper heat transfer copper fins An inclined fillet joint, or a wide-angle inclined fillet joint on the outer cylinder formed by abutting the other end surface of the heat transfer copper fin in the longitudinal direction of the inner surface of the outer cylinder, or the inner cylinder and the outer In the welding method of the heat transfer copper fin for metal cask, which is welded by composite welding of the preceding TIG and the subsequent MIG to the fillet joints formed on both surfaces of the cylinder,
An integrated TIG-MIG welding torch capable of composite welding of the preceding TIG and the subsequent MIG with respect to the weld line of the fillet joint to be welded, and silicon on the consumable wire on the subsequent MIG side A CuSi wire is used to attach the TIG-MIG welding torch to the distal end of a long arm that can travel and move or the wrist of an articulated movable welding robot via an attachment jig, and the non-consumable electrode of the preceding TIG The TIG welding power source is used to supply power with the polarity of the fillet joint side as the positive electrode, while the polarity of the CuSi wire of the subsequent MIG is the positive electrode and the polarity at the fillet joint side is the negative electrode The first welding current (Ia) fed from the TIG welding power source and the second welding current (Ib) fed from the MIG welding power source are fed by the MIG welding power source. (Ia / Ib) is output within a predetermined range, and the first welding current (Ia) flowing through the non-consumable electrode of the preceding TIG and the second welding current (Ib) flowing through the CuSi wire of the subsequent MIG, The TIG arc and the MIG arc that repel each other are generated at the welding start position of the fillet joint by the magnetic force of the repulsive action generated in the above, and one molten pool is formed by the repelling TIG arc and the MIG arc. Welding of heat transfer copper fin for metal cask characterized in that welding is performed from the start position to the end position of the weld line of the fillet joint portion by composite welding using the TIG arc, MIG arc and the one molten pool Method. In the welding method of the heat-transfer copper fin for metal casks of Claim 1,
The ratio (Ia / Ib) between the first welding current (Ia) fed from the TIG welding power source and the second welding current (Ib) fed from the MIG welding power source is in the range of 0.8 to 1.2. A method for welding a heat transfer copper fin for a metal cask, characterized in that: In the welding method of the heat transfer copper fin for metal casks of Claim 1 or 2,
At the welding start position of the weld line of the fillet joint portion, the shield gas composed of a mixed gas of Ar gas and He gas is allowed to flow out from the opening at the tip of the TIG-MIG welding torch, and the preceding TIG is not consumed. Immediately after the TIG arc of the negative electrode is generated between the electrode and the fillet joint and the first welding current (Ia) is reached to a steady value or after a predetermined time has elapsed, CuSi of the subsequent MIG The positive electrode MIG arc is generated behind the TIG arc between the wire and the fillet joint, and the second welding current (Ib) is reached to a steady value and repels each other. Immediately after the one molten pool is formed at the welding start position of the fillet joint by arc and MIG arc, or after a predetermined time has elapsed, the TIG-MIG welding torch must not be moved. Et al., The prior TIG and the subsequent MIG welding method of a metal cask Den Netsudo fins, characterized in that the hybrid welding to welding to the end position from the start position of the weld line of the fillet joint portion of. In the welding method of the heat transfer copper fin for metal casks of any one of Claims 1 thru | or 3,
In the case where the TIG-MIG welding torch is disposed at the distal end of a long arm that can be moved and moved, the TIG-MIG welding torch is positioned in front of the TIG-MIG welding torch and a predetermined distance from the weld line of the fillet joint. A guide roller that can be rotated and moved so as to contact and rotate on both surfaces of the surface portion of the heat transfer copper fin and the surface portion on the inner cylinder side or the surface portion on the outer cylinder side that are separated from each other. The composite TIG-MIG welding torch is guided in the direction of the welding line by the contact rotational movement of the guide roller, and the composite welding of the preceding TIG and the subsequent MIG is performed on the welding line of the fillet joint portion. A welding method for heat transfer copper fins for metal casks, wherein welding is performed from a start position to an end position. In the welding method of the heat transfer copper fin for metal casks of any one of Claims 1 thru | or 4,
The TIG-MIG welding torch arranged in the weld line direction of the fillet joint is provided with a non-consumable electrode of the preceding TIG, a CuSi wire of the subsequent MIG, its wire passage and a shield gas passage, and welding. The non-consumable electrode of the preceding TIG is inclined with respect to the vertical direction of the wire in a receding angle range of 0 to 45 degrees in the direction opposite to the welding progress direction, and the CuSi wire of the subsequent MIG is welded. It is arranged to be inclined at a forward angle range of 15 to 45 degrees on the direction side, and the distance interval between the tip portion of the non-consumable electrode and the tip portion of the CuSi wire is set in a range of 3 to 9 mm. While executing the traveling operation and welding operation of the TIG-MIG welding torch by the long arm traveling command, the output command to the TIG welding power source and the MIG welding power source, Welding method of the metal cask Den Netsudo fins, characterized by welding the composite welding of the trailing MIG row TIG end position from the welding start position of the welding line of the fillet joint. In the welding method of the heat transfer copper fin for metal casks of any one of Claims 1 thru | or 5,
One end face and fillet joint of the heat transfer copper fin on the inner cylinder side to be welded, or angle θ1 of the other end face and fillet joint of the heat transfer copper fin on the outer cylinder side, or the inner cylinder The angle θ1 between both end surface portions of the heat transfer copper fin formed on both surfaces of the outer cylinder and the fillet joint portion is relative to the outer surface of the inner tube, the inner surface of the outer tube, or both surfaces of the inner tube and the outer tube. Θ1 = 120 ± 15 degrees (105 ≦ θ1 ≦ 135 degrees), and the inclination angle θ2 on the inner cylinder side or the outer cylinder side is 30 degrees ± 15 degrees (15 ≦ θ2) with respect to the horizontal line. ≦ 45 degrees), and is welded from the welding start position to the end position of the weld line of the fillet joint by composite welding of the preceding TIG and the subsequent MIG or MIG welding. Welding method for heat transfer copper fin for cask. In the welding method of the heat transfer copper fin for metal casks of any one of Claims 1 thru | or 6,
When the composite welding of the preceding TIG and the subsequent MIG is performed on the weld line of the fillet joint portion using the heat transfer copper fin whose both end surfaces are flat surface shapes, the heat transfer is performed. The first distance S1 for shifting the position of the TIG-MIG welding torch from the end face corner b point of the copper fin to the surface side of the heat transfer copper fin is in the range of 0 to 4 mm, or the surface of the heat transfer copper fin The position of the TIG-MIG welding torch is shifted to the surface side of the heat transfer copper fin from the point a of the intersection position where the extension line of the inner surface and the surface line in the circumferential direction of the surface of the inner cylinder or the surface of the outer cylinder intersect The second distance S2 is S2 = S1 + T1 / tan (180−θ1) + G / sin (180, where T1 is the thickness of the heat transfer copper fin, θ1 is the fillet joint angle, and G is the gap. −θ1) and the range of the first distance S1. The TIG-MIG welding torch is set in a substantially downward position on the welding line in the position or range of the second distance S2, and the combined welding of the preceding TIG and the subsequent MIG is performed on the weld line of the fillet joint portion. A welding method for heat transfer copper fins for metal casks, wherein welding is performed from the start position to the end position. In the welding method of the heat transfer copper fin for metal casks of any one of Claims 1 thru | or 6,
When performing MIG welding using a MIG welding torch, a CuSi wire, and a MIG welding power source instead of the composite welding of the preceding TIG and the subsequent MIG, from the corner b of the end face of the heat transfer copper fin, The first distance S1 for shifting the position of the MIG welding torch to the surface side of the heat transfer copper fin is in the range of -1.9 to 3.1 mm, or the extension line of the surface of the heat transfer copper fin and the inner The second distance S2 for shifting the position of the MIG welding torch from the point a of the intersection position where the surface of the cylinder or the surface of the outer cylinder in the circumferential direction intersects to the surface side of the heat transfer copper fin is When the plate thickness of the heat transfer copper fin is T1, the angle of the fillet joint is θ1, and the gap is G, S2 = S1 + T1 / tan (180−θ1) + G / sin (180−θ1), A range position of the first distance S1, or For the metal cask characterized in that the MIG welding torch is set on the welding line in the range of the distance S2 of 2 and the MIG welding is welded from the start position to the end position of the fillet joint portion. Welding method for heat transfer copper fins. In the welding method of the heat-transfer copper fin for metal casks of Claim 8,
When the MIG welding is performed on the weld line of the fillet joint portion using the heat transfer copper fin whose both end surfaces are inclined surfaces, the first distance S1 is in the range of 0 to 4 mm. Or the second distance S2 is defined as follows: the thickness of the heat transfer copper fin is T1, the end face inclination angle of both end faces of the heat transfer copper fin is β1, the angle of the fillet joint is θ1, and the gap is G , S2 = S1 + T1 / tan (180−θ1) −T1 × tan β1 + G / sin (180−θ1), and welding in the range position of the first distance S1 or the range position of the second distance S2. A method for welding a heat transfer copper fin for a metal cask, wherein the MIG welding torch is set on a wire, and the MIG welding is performed from the start position to the end position of the fillet joint portion. In the welding method of the heat transfer copper fin for metal casks of any one of Claims 1 thru | or 9,
At least a shielding plate capable of shielding radiant heat and scattered matter is used, and the shielding plate is the TIG-MIG welding torch or the MIG welding torch for welding in the weld line direction of the fillet joint, and the TIG-MIG welding. The front portion of the heat transfer copper fin and the surface portion on the inner cylinder side or the outer cylinder side at a position closer to the front than the torch or the MIG welding torch and a short distance from the weld line of the fillet joint portion Between the guide roller and a rotatable movable guide roller arranged to rotate in contact with both surfaces of the surface portion, and at the upper position in a direction substantially perpendicular to the welding line, the tip of the long arm is below the tip portion. For a metal cask characterized in that a shielding plate is provided and the shielding plate shields radiant heat and scattered matter generated during welding by the TIG-MIG welding torch or the MIG welding torch. Welding method of Netsudo fin. In the welding method of the heat transfer copper fin for metal casks of any one of Claims 1 thru | or 10,
Welding formed in the fillet joint between the outer surface of the inner tube or the inner surface of the outer tube and one end surface of the heat transfer copper fin, which is welded by the composite welding of the preceding TIG and the subsequent MIG or the MIG welding Or a throat thickness L of a welded portion formed at a fillet joint between both the inner and outer cylinders and both end surfaces of the heat transfer copper fin is at least a plate thickness T1 of the heat transfer copper fin ( A welding method for heat transfer copper fins for metal casks, characterized by having a size of L ≧ T1). Inclined at substantially equal intervals between the outer surface of the steel inner cylinder that houses the assembly of spent fuel containing radioactive materials and the inner surface of the steel outer cylinder that is coaxially disposed outside the inner cylinder. A wide angle on the inner tube side formed by abutting one end surface portion of the heat transfer copper fin in the longitudinal direction of the outer surface of the inner tube when welding both end surfaces of the predetermined number of copper heat transfer copper fins to be deployed An inclined fillet joint part, or a wide-angle inclined fillet joint part on the outer cylinder side formed by abutting the other end surface part of the heat transfer copper fin in the longitudinal direction of the inner surface of the outer cylinder, or the inner cylinder and In a welding apparatus for heat transfer copper fins for metal cask that is welded by composite welding of preceding TIG and subsequent MIG to fillet joints formed on both sides of the outer cylinder,
An integrated TIG-MIG welding torch capable of at least composite welding of the preceding TIG and the subsequent MIG to the weld line of the fillet joint to be welded, and silicon containing consumable electrodes on the subsequent MIG side A CuSi wire, a seal gas that allows gas to flow from the tip of the TIG-MIG welding torch toward the welded portion of the fillet joint and the vicinity thereof, and a jig for attaching the TIG-MIG welding torch to the tip of the arm. A TIG welding power source for supplying power with a long arm that can be attached to the front and being movable in the welding direction, and the polarity of the non-consumable electrode of the preceding TIG is the negative polarity and the polarity on the fillet joint side is the positive polarity And a MIG welding power source that performs power feeding and wire feeding with the polarity of the CuSi wire of the subsequent MIG as a positive electrode and the polarity at the fillet joint side as a negative electrode,
The first welding current (Ia) supplied from the TIG welding power source and the MIG welding while letting out the shielding gas from the tip of the TIG-MIG welding torch at the start position of the weld line of the fillet joint. The ratio (Ia / Ib) to the second welding current (Ib) fed from the power source is output within a predetermined range, and the first welding current (Ia) flowing through the non-consumable electrode of the preceding TIG and the subsequent MIG The repulsive magnetic force generated by the second welding current (Ib) flowing through the consumable wire generates a TIG arc and a MIG arc that repel each other at the welding start position of the fillet joint, and repels each other. One melt pool is formed by the TIG arc and the MIG arc, and the weld line of the fillet joint is formed by composite welding using the TIG arc, the MIG arc, and the one melt pool. Welding device for a metallic cask Den Netsudo fins, characterized by welding to the end position from the start position. In the welding apparatus of the heat transfer copper fin for metal casks of Claim 12,
The ratio (Ia / Ib) between the first welding current (Ia) fed from the TIG welding power source and the second welding current (Ib) fed from the MIG welding power source is in the range of 0.8 to 1.2. A welding apparatus for heat transfer copper fins for metal casks. In the welding apparatus of the heat transfer copper fin for metal casks of Claim 12 or 13,
The front portion of the heat transfer copper fin and the surface portion on the inner cylinder side or the surface on the outer cylinder side at a front position of the TIG-MIG welding torch and separated from the weld line of the fillet joint portion by a short distance A guide roller is arranged on the lower side of the long arm so as to rotate in contact with both sides of the part, and the leading TIG-MIG welding torch is caused to travel in the direction of the welding line by the contact rotation of the guide roller. Heat transfer copper fin for metal cask characterized in that welding is performed from the start position to the end position of the weld line of the fillet joint portion by composite welding with the TIG arc of the MIG and the subsequent MIG and the one molten pool Welding equipment. In the welding apparatus of the heat transfer copper fin for metal casks of Claim 14,
The tip end of the long arm is located at a position forward of the TIG-MIG welding torch and the guide roller and at an upper position substantially perpendicular to the welding line. A welding apparatus for heat transfer copper fins for metal casks, characterized in that a shielding plate capable of shielding at least radiation heat and scattered matter is disposed on the lower side.

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