JP2002361425A - Inert gas arc welding method and equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a TIG(tungsten inert gas) welding method and equipment, a type of inert gas arc welding method and equipment which enable reduction of man-hour for welding through effective cooling that is important particularly in the welding of a zirconium material, enable enhancement of economical efficiency through reduction in the use of an inert gas such as Ar gas, and realize a weld zone of stable quality. SOLUTION: In the TIG welding, an arc is generated between a tungsten electrode 16 and the tip grooves a, b of zirconium-used steel tubes W1 , W2 in an Ar gas atmosphere to carry out welding with the heat of the arc. A gas cooling device 30 is arranged midway in a gas feeding pipe 18 between an Ar gas cylinder 17 and a workpiece holder 20 and cools the Ar gas to a temperature of -50 to -60 deg.C. The cooled Ar gas G2 , G3 is sent to the workpiece holder 20 and supplied from the outside of a steel tube butt-weld zone as an after shielding gas G2 ; it is also sent into the steel tube and supplied from the inside of the butt-weld zone as a back shielding gas G3 . As a result, the cooling speed of the weld zone is increased, thus, reducing the welding performance time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an inert gas arc welding method and welding apparatus.

[0002]

2. Description of the Related Art Inert gas arc welding is a process in which a bare tungsten electrode rod or a metal electrode wire is energized in an atmosphere of an inert gas (inert gas) which does not react with a metal even at a high temperature, such as argon or helium, and a gap between the electrode and a welding work. In this method, an arc is generated and welding is performed using the heat. TIG welding (TIG; Inert-Gas Tungsten-arc weldin) is used when a bare tungsten electrode rod and filler metal (welding rod) are used.
g) In addition, the case where a metal electrode wire is used also as a filler material is known as MIG welding.

[0003] Zirconium, which is used as a material for welding work, is superior in corrosion resistance to other industrial materials such as stainless steel, so that various parts of plant equipment for chemical, nuclear and nuclear fuel reprocessing, piping, etc. It is frequently used as a high corrosion resistant structural material. When the welding work made of zirconium is a steel pipe or a thin plate, it is difficult to weld it by the conventional covering arc welding method or gas welding method. Instead, the above-mentioned TIG welding, which is a kind of inert gas arc welding, is often used. ing.

[0004] Zirconium itself has good weldability, but is an active metal like titanium and the like, and easily reacts with gas components such as oxygen and nitrogen in the air at high temperatures to easily cause oxidation and nitridation. For this reason, even when performing TIG welding, it is necessary to effectively cool the welding site during high-temperature welding.

FIG. 5 shows a conventional example of a TIG welding apparatus used for welding a zirconium material. Inert argon (A) obtained by vaporizing liquefied argon in the welding machine 1
r) Gas is supplied from the cylinder 2 and Ar gas is fed into the welding torch 4 connected by the cab tire 3. The cab tire 3 includes an inert gas-based gas supply pipe that sends Ar gas,
Wires and cables that supply power supply voltage from the welding machine 1 are bundled together. The welding torch 4 has a tungsten electrode rod 6 on the central axis of the gas nozzle 5 and a few mm outside.
By protruding and peeking, an arc is generated between the welding machine 1 and the welding work W by energization from the welding power source, thereby welding the welding rod, which is a filler metal, by melting the welding rod with the heat generated by the arc.

Another Ar gas cylinder 7 is provided for suppressing oxidation and nitriding due to high temperature during welding and for cooling, and Ar gas is supplied from the gas supply pipe 8 to the welding portion of the welding work W for after-shielding. And supplied as welding shield gas for back shield. The gas supply pipe 8 is divided from the middle into two branch pipes 8a and 8b. From one of the branch pipes 8a, Ar gas is sent to the work holding jig 9 as an after-shielding gas, and from the outside to the welding portion of the welding work W. The after-shield gas is blown. In addition, Ar gas is sent from the other branch pipe 8b to the work holding jig 9 as back shield gas, and the back shield gas is blown from the inside to the welding portion of the welding work W.
The welding work W is welded in such a work holding jig 9 in an Ar gas atmosphere.

[0007]

The conventional TIG welding apparatus shown in FIG. 5 has the following improvements particularly in welding a welding work W made of a zirconium material.

Although a TIG welding device originally requires a long welding time, a welding work W made of zirconium material is required.
Especially when welding, the time spent on cooling is long,
The fact is that most of the welding time is taken. In addition, the cooling time fluctuates depending on the season and weather, which is a serious problem in terms of welding quality and process control.
Also, the longer the welding construction time and cooling time, the more
The use amount of Ar gas also increases, which is uneconomical.

Accordingly, an object of the present invention is to reduce the number of man-hours for welding by effectively performing cooling, which is particularly important for welding zirconium materials, and to reduce the amount of inert gas such as Ar gas to be economical. It is an object of the present invention to provide a TIG welding method and apparatus, which is a kind of inert gas arc welding method and apparatus capable of obtaining a welded part of stable quality while increasing the welding quality.

[0010]

In order to achieve the above object, an inert gas arc welding method according to the first aspect of the present invention provides an inert gas arc welding method in which an arc is formed between a welding work and an electrode in an inert gas atmosphere. In generating and performing welding with the heat, the inert gas is cooled to a predetermined temperature, and then supplied to a welding portion of the welding work as a welding shield gas.

As described above, before the inert gas is supplied as a welding shield gas to the welding portion of the welding work, the inert gas is cooled and cooled to a low temperature, so that oxidation due to the high temperature of the welding portion can be prevented. Suppressing nitridation and accelerating the cooling shorten the welding time and reduce the amount of inert gas used, which is economical.

An inert gas lure according to claim 2
As shown in FIGS. 1 and 2, the welding method
Steel pipes on one side and the other side to which butt W is butt-welded
W₁, W ₂Ar gas that has become low temperature after cooling
Such as inert gas as welding shielding gas
It is supplied from the outside to the joint welding area and the inside of the steel pipe is
Supply from the inside to the butt weld site through
Features.

As described above, when the welded workpiece W is the steel pipes W ₁ and W ₂ to be butt-welded, the welding shield gas of the cooled and cooled Ar gas is used as an after-shield gas G ₂ at the steel pipe butt welding portion. The welding shield gas, which has been cooled, is passed through the inside of the steel pipes W ₁ and W ₂ , and is contacted and supplied as a back shield gas G ₃ from the inside of the steel pipe butt welding portion. That is, since the steel pipe butt welding portion is cooled from the inside and the outside by the low-temperature welding shield gas, it is effective to suppress the temperature rise of the steel pipe butt welding portion.

The inert gas arc welding method according to claim 3 is characterized in that the welding work is made of zirconium.

From the above, welding of a zirconium material is difficult by conventional covering arc welding or gas welding, and TIG welding, which is a kind of inert gas arc welding, can be employed. Even in such a case, the zirconium material easily generates oxides and nitrides at a high temperature due to welding heat. Therefore, cooling for suppressing the high temperature is an important issue. Therefore, even when the welding work W is a steel pipe W ₁ , W ₂ made of a zirconium material, A supplied as a welding shielding gas is used.
By pre-cooling the inert gas such as r gas to a low temperature state, the cooling during the welding of the steel pipe is accelerated, and for example, the quality of the butt-welded welding portion can be satisfactory.

In the inert gas arc welding apparatus according to a fourth aspect of the present invention, as shown in FIG. 1, the welding portion of the welding work W positioned and held by the work holding jig 20 is formed of argon (Ar) gas. An arc is generated between the electrode 16 and the atmosphere in an inert gas atmosphere, and welding is performed by the heat. The inert gas is supplied from the inert gas supply cylinder 17 to the work holding jig 20. A gas cooling device 30 is provided in the middle of the gas supply pipe 18 to be supplied, and the inert gas cooled to a predetermined temperature in the gas cooling device 30 is supplied as a welding shield gas to a work welding portion inside the work holding jig 20. It is characterized by having such a configuration.

With the above configuration, a gas cooling device 30 is provided in the middle of the gas supply pipe 18 for an inert gas such as Ar gas, and the gas cooling device 30 cools the Ar gas cooled to a predetermined temperature to a low temperature. It is fed into the work holding jig 20 as a welding shield gas. In the work holding jig 20, the welding portion of the welding work W is positioned and held, and the welding is performed in the supplied low-temperature welding shield gas atmosphere. Can be.

In the inert gas arc welding apparatus according to the fifth aspect, as shown in FIG. 2, a steel pipe W on one side and another side on which a welding work W is butt-welded as a specific example.
_In the case of ₁ and W2, _two gas supply pipes 19a and 19b for supplying the welding shield gas cooled from the gas cooling device 30 and having a low temperature toward the work holding jig 20 are provided. The gas supply pipe 19a supplies the low-temperature welding shield gas from outside to the steel pipe butt welding portion positioned in the work holding jig 20, and the other gas supply pipe 19b supplies the low-temperature welding shield gas to the inside of the steel pipe. The butt-welding portion is supplied from inside through the butt-welding portion.

With the above configuration, the welding work W is
₁ , W ₂ , the temperature of the gas cooled by the gas cooling device 30 A
Work holding jig 2
Two gas supply pipes 19a and 19b for supplying 0 are provided. From one of the gas supply pipe 19a, supplied from the outside to the welding site butt steel cold welding shielding gas is contacted as after-shield gas G _2. Also, from the other gas supply pipe 19b, also supplies cold welding shielding gas from the interior of the welded part butt through the interior of the steel pipe by contacting a back shield gas G _3. By supplying a low-temperature welding shield gas from the inside and outside of the steel pipe butt welding portion in this way, it is possible to suppress the increase in the temperature of the steel pipe butt welding portion and to accelerate the cooling.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a TIG welding method and apparatus as an embodiment of an inert gas arc welding method and apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a TIG welding apparatus according to this embodiment. The apparatus includes a welding machine body 10, a welding torch 14 connected to the welding machine body 10 by a cab tire 13, a work holding jig 20, two Ar gas cylinders 11, 17, and the like.
From the Ar gas cylinder 11, inert Ar gas obtained by evaporating liquefied argon is supplied to the welding machine 10 from the gas supply pipe 12, and is sent through the cab tire 13 to the welding torch 14. The cab tire 13 forms a gas supply pipe of an inert gas system for sending Ar gas, an electric wire / cable for supplying a voltage from a welding power source of the welding machine 10, and in this case, a circulation system of cooling water sent to the welding torch 14. Cooling water pipes are bundled together.

The welding torch 14 has a tungsten electrode rod 16 projecting several millimeters outwardly on the central axis of the gas nozzle 15 to allow the same to be viewed. And an arc is generated between the welding work W and the welding portion of the welding work W while the welding rod serving as the filler material is melted by the heat generated by the arc.

[0023] Figure 2, whereas when welding butt steel pipe W ₁ and the other side of the steel pipe W ₂ side on the axis, is a side sectional view showing a work holding jig 20 which is positioned and held the butt weld site. The tips of both steel pipes are chamfered to form grooves a and b, and a bead is raised between the grooves a and b for welding. Its steel W ₁ of one side of the groove-welding portion as a center is respectively the other side of the steel pipe W ₂ of, are positioned in the form of being covered and protected by inserting a cylindrical body housing 21 of the work holding jig 20 You. That is, by inserting a steel tube W ₁ of one side from one side opening end 21a of the body housing 21, by inserting the steel pipe W ₂ of the other side from the other side opening end 21b, a groove portion a in the main body housing center, The opposite ends of the steel pipes W ₁ and W ₂ are positioned by abutting b.

In FIG. 2, the gas nozzle 15 of the welding torch 14 is inserted into the main body housing 21 from above, and the tungsten electrode rod 16 protruding from the nozzle end is opposed to the groove portions a and b. At a suitable facing distance that can generate Gas nozzle 15
Is normally Ar gas G ₁ of the temperature shown in the drawing the white arrow, which is supplied through the cabtire 13 from Ar gas cylinder 11, is blown to the peripheral portion abutting the steel pipe and the center groove portion a, b Supply.

In FIG. 1, an Ar gas cylinder 17 supplies Ar gas to a work holding jig 20 through a gas supply pipe 18. In the middle of the gas supply pipe 18, a gas cooling device 30, which is a main part of the device of the present invention, is arranged. This gas cooling device 30
The two gas supply pipes 19 are provided between the
a, 19b. That is, the Ar gas supplied from the Ar gas cylinder 17 is once cooled in the gas cooling device 30, and the cooled Ar gas is used as a welding shield gas for the one and the other gas supply pipes 19a, 1.
9b is sent out toward the work holding jig 20.

One gas supply pipe 1 from the gas cooling device 30
Welding shield gas at a low temperature of Ar gas fed to 9a, as shown by a broken line arrow in FIG. 2, are fed into the main body housing 21 of the work holding jig 20 as aphthous shield gas G ₂ inert gas Create an atmosphere. In such an inert gas atmosphere, for supplying the after shield gas G ₂ steel groove portion a, all directions of the butt welding site around the b. Further, the welding shield gas by the low-temperature Ar gas sent from the gas cooling device 30 to the other gas supply pipe 19b is positioned and held in the main body housing 21 by the steel pipe W ₁ as shown by the broken arrow in FIG. It is passed as a back shield gas G ₃ from one side to the tube of the W ₂ to the other side. The back shield gas G ₃ are supplied from the inside all directions of the welding site around the steel pipe groove portion a, a b.

FIGS. 3 and 4 show such a gas cooling device 3.
FIG. 2 is a cross-sectional view schematically showing an internal structure of a No. 0. That is,
The apparatus has a cooling tank 31 which is a main body of the apparatus. In the cooling tank 31, an antifreeze liquid 32 is substantially filled and accommodated in the tank in order to enhance a cooling effect. A gas flow pipe 33 made of copper (Cu) is accommodated in the antifreeze liquid 32 in a meandering shape. The upstream inlet 33a side of the gas flow pipe 33 is connected to the gas supply pipe 18 from the Ar gas cylinder 17 shown in FIG. Further, as shown in FIG. 4, the upstream side 33a of the gas flow pipe 33 is provided with, for example, six systems of six lines. The downstream outlet 33b side of the gas flow pipe 33 is integrated into two, and the two gas supply pipes 19a, 19
b.

With the above configuration, the TIG of this embodiment is
In the welding device, as shown in FIG. 2, steel pipes W ₁ and W ₂ made of a zirconium material as welding work W are positioned and held on a work holding jig 20 by abutting the tips a and b of these pipes. 14 for welding.

By turning on the power to the welding machine 10,
Ar gas, which is an inert gas obtained by vaporizing liquefied argon, is supplied from the two Ar gas cylinders 11 and 17 almost in synchronization. Ar gas G ₁ from Ar gas cylinder 11 is supplied to the welding torch 14 via a cabtire 13, as shown in FIG. 2, it is blown out toward the gas nozzle 15 steel pipe groove portion a, the b at normal temperature. Oxidation and nitridation during welding are suppressed by the supply of the welding shield gas.

On the other hand, A from the Ar gas cylinder 17
The r gas is sent into the gas cooling device 30 at a gas flow rate of, for example, 200 liters per minute, where it is passed through a copper gas flow pipe 33 immersed in an antifreeze liquid 32.
Cool to -60 ° C. Ar gas cooled to a low temperature is passed through one of the gas supply pipe 19a as aphthous shield gas G _2, fed into the main body housing 21 of the work holding jig 20, the center steel pipe groove portion a, b welding It is supplied from outside over the entire circumference of the site. As such by supplying from the outside to the welding site butt steel cold after-shield gas G _2, and at the same time to suppress oxidation and nitridation, hasten the cooling of the welding site.

In the gas cooling device 30, -50 to
Ar gas cooled to −60 ° C. is supplied to the other gas supply pipe 1.
Back shield gas G on 9b₃Threaded as a work steel
Tube W ₁, W₂Into the pipe from one side to the other
You. That is, such back shield gas G₃The steel pipe
Supplied from the inside over the entire circumference of the welded part of the groove a, b
By suppressing oxidation and nitridation,
Hasten cooling.

As described above, the welding shield gas of Ar gas is cooled by the gas cooling device 30 to lower the temperature, and then sent separately for the after-shield gas and the back-shield gas. By supplying over the entire circumference of the welding portion, the cooling rate of the welding portion, which becomes high in temperature due to welding heat, can be increased. As a result, the welding time is greatly reduced, and the amount of Ar gas used is also drastically reduced, thereby improving the economic efficiency.

Table 1 shows that a sample was taken from the butt-welded portion of the steel pipe thus obtained, and this was taken as "Example", and a sample obtained by the conventional apparatus shown in FIG. Each welding time and quality are compared and shown.

[0034]

[Table 1]

As is clear from Table 1, the welding time required for welding is about 8 in the case of the embodiment by supplying the welding shield gas by Ar gas to the steel pipe butt portion after cooling by the gas cooling device 30 to lower the temperature. Time, which is greatly reduced to 1/5 of the conventional 40 hours. Also, in the evaluation based on the “color tone inspection judgment standard” which is a standard for the quality test of the zirconium material, it can be seen that the inner and outer surface color tone of the steel pipe butt welding portion and the base metal portion satisfy the acceptance criteria.

The above-mentioned color tone inspection criterion generally evaluates the quality of a shield at the time of welding because oxygen and nitrogen, etc., in a zirconium welded joint increase tensile strength but decrease ductility of the joint. It is necessary to determine the quality of the shield. Specifically, in the welding of zirconium materials, the color tone changes from “silver” to “gold”, “blue”, and “gray” depending on the shielding condition, and the bending performance is within the range of “gold” to “blue”. Is secured. Overall, as in the case of welding titanium materials, "Silver", "Gold or Wheat" and "Purple or Blue" are accepted, and "Blue or Gray" and "White or Yellow White" are rejected. Judgment is appropriate.

From Table 1, it can be seen that the conventional example satisfies the tentative color tone standard and the quality of the welded part is acceptable, but it takes a long welding time of 40 hours to reach the acceptance judgment. -ing

[0038]

As described above, in the inert gas arc welding method according to the first aspect of the present invention, the inert gas is supplied at the stage before the supply of the inert gas as the welding shield gas to the welding portion of the welding work. Cooling the active gas and keeping it at a low temperature suppresses oxidation and nitridation due to the high temperature of the welded part, and shortening the welding time by speeding up the cooling reduces the amount of inert gas used, making it economical. It is.

In the inert gas arc welding method according to the present invention, when the welding work is a steel pipe to be butt-welded, a welding shield gas such as Ar gas cooled to a low temperature after cooling is applied to the steel pipe butt welding portion. The shield gas is supplied in contact with the outside from the outside, and the low-temperature welding shield gas is also passed through the inside of the steel pipe to be contacted and supplied as the back shield gas from inside the butt welding portion of the steel pipe. That is, since the steel pipe butt welding portion is cooled from the inside and the outside by the low-temperature welding shield gas, it is effective to suppress the temperature rise of the steel pipe butt welding portion.

In the inert gas arc welding method according to the third aspect, welding of a zirconium material is difficult by conventional covering arc welding or gas welding, and TIG welding, which is a type of inert gas arc welding, can be employed. . Even in such a case, the zirconium material easily generates oxides and nitrides at a high temperature due to welding heat. Therefore, cooling for suppressing the high temperature is an important issue. Therefore, even when the welding work is a steel pipe made of a zirconium material, the cooling during the welding of the steel pipe is achieved by previously cooling the inert gas such as Ar gas supplied as the welding shielding gas to a low temperature state. As soon as possible, for example, satisfactory quality of the butt-welded weld site can be obtained.

In the inert gas arc welding apparatus according to a fourth aspect of the present invention, a gas cooling device is provided in a gas supply pipe for an inert gas such as Ar gas, and the gas cooling device is controlled to a predetermined temperature. Ar gas or the like cooled to a low temperature is sent to a work holding jig as a welding shield gas. In the work holding jig, the welding portion of the welding work is positioned and held, and the welding is performed in a supplied low-temperature welding shield gas atmosphere. Therefore, the temperature of the welding portion can be suppressed from becoming high and cooling can be accelerated. .

Further, in the inert gas arc welding apparatus according to the fifth aspect, when the welding work is a steel pipe, a welding shield gas such as Ar gas cooled to a low temperature by a gas cooling apparatus is supplied to the work holding jig. A gas supply pipe is provided. From one of the gas supply pipes, a low-temperature welding shield gas is supplied to the steel pipe butt welding portion from the outside as an after-shield gas so as to come into contact therewith. Further, from the other gas supply pipe, a low-temperature welding shield gas is also supplied through the inside of the steel pipe so as to be brought into contact with the inside of the butt welding portion as a back shield gas. By supplying a low-temperature welding shield gas from the inside and outside of the steel pipe butt welding portion in this way, it is possible to suppress the increase in the temperature of the steel pipe butt welding portion and to accelerate the cooling.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a TIG welding apparatus as an embodiment of inert gas arc welding according to the present invention.

FIG. 2 is a side cross-sectional view showing a mode of supplying a welding shield gas with Ar gas cooled and cooled to a steel pipe welding portion of a welding work positioned and held by a work holding jig.

FIG. 3 is a front sectional view schematically showing a gas cooling device provided as a main part of the present device.

FIG. 4 is a side view of the gas cooling device.

FIG. 5 is a configuration diagram showing a conventional TIG welding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Welding machine body 11, 17 Ar gas cylinder 12, 18 Gas supply pipe 13 Cab tire 14 Welding torch 15 Gas nozzle 16 Tungsten electrode rod 19a, 19b Gas supply pipe 20 Work holding jig 21 Main body housing 21a, 21b Work insertion port 30 Gas cooling device 31 cooling tank 32 antifreeze 33 gas flow pipe made of Cu

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E001 AA03 BB07 CC03 DD01 4E081 AA12 BA27 BB15 CA11 DA05 DA31

Claims (5)

[Claims] 1. An inert gas arc welding method in which an arc is generated between a welding work and an electrode in an atmosphere of an inert gas and welding is performed by the heat, wherein the inert gas is cooled to a predetermined temperature. And an inert gas arc welding method, wherein the inert gas is supplied as a welding shield gas to a welding portion of the welding work. 2. When the welding work is a steel pipe on one side and the other side to be butt-welded, the cooled welding shield gas is supplied from the outside to the butt-welding portions of both steel pipes, and is passed through the inside of the steel pipe. The inert gas arc welding method according to claim 1, wherein the inert gas arc is supplied to the butt welding portion from the inside. 3. The inert gas arc welding method according to claim 1, wherein the welding work is made of zirconium. 4. An inert gas arc welding apparatus for generating an arc between an electrode and an electrode in an atmosphere of an inert gas and welding the welded portion of a welded work positioned and held by a work holding jig with the heat thereof. A gas cooling device is provided in the middle of a gas supply pipe for supplying an inert gas from the supply source of the inert gas to the work holding jig, and the inert gas cooled to a predetermined temperature in the gas cooling device is welded. An inert gas arc welding apparatus characterized in that the inert gas arc welding apparatus is configured to be supplied as a shielding gas to a welding site inside the work holding jig. 5. In the case where the welded work is a steel pipe on one side and the other side to be butt-welded, two gas supplies for supplying a cooled welding shield gas from the gas cooling device to the work holding jig. A pipe is provided, one of the gas supply pipes supplies a welding shield gas from the outside to a butt welding portion of the two steel pipes inside the work holding jig, and the other gas supply pipe passes the welding shield gas through the steel pipe. The inert gas arc welding device according to claim 4, wherein the inert gas arc welding device is supplied from the inside to the butt welding portion.