JP2009166109A - Crater treatment method of two-electrode arc welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform satisfactory crater treatment in two-electrode arc welding to perform welding by using a welding torch provided with a consumable electrode 11 disposed within a shielding gas nozzle 43 for discharging a shielding gas 62, and a non-consumable electrode 12, and generating a consumable electrode arc 31 and a non-consumable electrode arc 32. <P>SOLUTION: When ending a welding operation, the crater treatment is performed by extinguishing the consumable electrode arc 31 while keeping continuing feeding of the consumable electrode 11, and melting the consumable electrode 11 by the non-consumable electrode arc 32. Thereby, the consumable electrode 11 is stably melted, and therefore, the generation of sputter can be suppressed. Also, during the crater treatment, the front end of the consumable electrode 11 is put into a short circuit state from a molten pool 2 to keep a heating current supplied to the consumable electrode 11. Further, when ending the crater treatment, the non-consumable electrode arc 32 is extinguished with a delay after stopping feeding of the consumable electrode 11, and thereby the welding of the consumable electrode 11 is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention performs good crater treatment in two-electrode arc welding in which a consumable electrode arc and a non-consumable electrode arc are generated using a welding torch having a consumable electrode and a non-consumable electrode disposed in a shield gas nozzle. The two-electrode arc welding crater treatment method.

  Simultaneously generating a consumable electrode arc while supplying a welding wire as a consumable electrode and generating a non-consumable electrode arc including the above consumable electrode arc using argon gas or the like as a plasma gas 2 Electrode arc welding has been proposed (see, for example, Patent Document 1). FIG. 5 is a schematic diagram showing the structure of the welding torch 4 and the arc generating portion in this two-electrode arc welding method. The consumable electrode (welding wire) 11 is supplied with power from a power supply tip 41 provided at the center of the welding torch 4 and is fed along the central axis so that a consumable electrode arc 31 is formed between the base electrode 2 and the consumable electrode. appear. The non-consumable electrode 12 has a hollow, substantially cylindrical shape, and a non-consumable electrode arc (plasma arc) 32 is generated between the non-consumable electrode 12 and the base material 2. Since the consumable electrode 11 is fed through the insulated hollow of the non-consumable electrode 12, the consumable electrode arc 31 is surrounded by the non-consumable electrode arc 32. Outside the non-consumable electrode arc 32, a plasma gas (not shown) flows to form a plasma arc by thermally constraining the arc, and a shield gas (not shown) flows further outside. Argon gas or the like is often used for the plasma gas and the shield gas. Since the consumable electrode arc 31 is shielded by argon gas, MIG welding is used.

  In the two-electrode arc welding as shown in the figure, since the non-consumable electrode arc (plasma arc) 32 is thermally restrained by plasma gas or the like, the molten pool 21 is separated from the non-consumable electrode arc 32 and the consumable electrode arc 31. The arc force received is larger than TIG welding, MIG welding, MAG welding and the like. That is, in the two-electrode arc welding, the surface of the molten pool 21 receives a high dynamic pressure due to the dynamic pressure of the plasma gas and the arc force from the non-consumable electrode arc 32 and the consumable electrode arc 31. In such welding under a high arc pressure, the shape of the surface of the molten pool 21 becomes concave as shown in FIG.

  This method of supplying heat to the base material 2 from both the consumable electrode arc 31 and the non-consumable electrode arc 32 and supplying the molten consumable electrode 11 is suitable for high-efficiency welding in which welding is performed at a relatively high welding speed. ing. However, in high-efficiency welding, the faster the welding speed, the more difficult it is to end the welding process appropriately. Inappropriate treatment of the weld end causes defects at the end of the weld bead.

  Considering the welding end portion in the above-described two-electrode arc welding, if the non-consumable electrode arc 32 and the consumable electrode arc 31 are simultaneously extinguished, the surface shape of the crater portion becomes concave or the surplus of beads during steady welding. The extra height is lower than the height. A crater portion having a concave shape or a crater portion having a low surplus is mechanically weak, and sufficient welding strength may not be obtained. In addition, crater treatment generally used in MIG welding, MAG welding, etc. There is a method of performing crater treatment by reducing the action of arc pressure on the molten pool 21. However, even in this crater process, since the non-consumable electrode arc 32 exists, the melting of the consumable electrode 11 is promoted, so that the arc length of the consumable electrode arc 31 cannot be shortened. Since the dynamic pressure acts on the molten pool 21, it is inevitable that the concave crater portion or the surplus of the crater portion is lowered (see, for example, Patent Documents 2 and 3).

JP 63-168283 A JP 59-7480 A Japanese Patent Laid-Open No. 9-192832

  As described above, in the conventional two-electrode arc welding crater processing method, there is a case where a sound welding terminal bead cannot be formed. In order to improve this, Japanese Patent Application No. 2007-209262 filed on Aug. 10, 2007 proposes a crater processing method by the same applicant as the present invention. In this two-electrode arc welding crater treatment method, the crater treatment is performed at the same time that the non-consumable electrode arc is extinguished, and the crater treatment is performed only with the consumable electrode arc. As a result, the arc force to the molten pool can be weakened, and since the melting of the consumable electrode is performed only by the consumable electrode arc, the arc length can be set short, and a healthy weld end bead can be formed. it can.

  However, during the crater process by the consumable electrode arc, the short circuit state and the arc generation state are repeated between the consumable electrode and the base material. For this reason, spatter occurs. As described above with reference to FIG. 5, since the structure of the two-electrode arc welding torch is complicated, if spatter adheres to the inside, the welding quality deteriorates and the maintenance takes time. Therefore, in the crater process of the two-electrode arc welding, it is required that a sound welding end bead is formed and the generation of spatter is small.

  Accordingly, an object of the present invention is to provide a crater treatment method for two-electrode arc welding that can form a sound welding end bead and that generates less spatter.

In order to solve the above-described problem, the first invention
Crater treatment of two-electrode arc welding in which welding is performed by generating a consumable electrode arc and a non-consumable electrode arc using a welding torch having a consumable electrode and a non-consumable electrode disposed in a shield gas nozzle for discharging a shield gas In the method
At the end of welding, the consumable electrode arc is extinguished while continuing to feed the consumable electrode, and the consumable electrode is melted by the non-consumable electrode arc to perform crater treatment.
A crater treatment method for two-electrode arc welding.

In a second aspect of the present invention, during the crater process, the tip of the consumable electrode is short-circuited with the molten pool, and a heating current is applied to the consumable electrode.
A two-electrode arc welding crater treatment method according to the first aspect of the present invention.

In a third aspect of the present invention, at the end of the crater process, the feeding of the consumable electrode is stopped and then the non-consumable electrode arc is extinguished after being delayed.
A crater treatment method for two-electrode arc welding according to the first or second invention.

According to a fourth aspect of the present invention, at the end of the crater process, the consumable electrode is stopped after being reversely fed, and the non-consumable electrode arc is extinguished simultaneously or delayed.
A crater treatment method for two-electrode arc welding according to the first or second invention.

  According to the first aspect of the invention, at the end of welding, the consumable electrode arc is extinguished while the supply of the consumable electrode is continued, and the consumable electrode is melted by the non-consumable electrode arc to perform crater processing. For this reason, since the consumable electrode is stably melted by the non-consumable electrode arc, it is possible to prevent the occurrence of sputtering. Furthermore, since the crater treatment is performed only with the non-consumable electrode arc, the arc force to the molten pool is weakened, and a sound weld end portion bead can be formed.

  According to the second aspect of the invention, during the crater treatment, the tip of the consumable electrode is short-circuited with the molten pool, and a heating current is applied to the consumable electrode. For this reason, in addition to the effect of the first invention, the consumable electrode is heated and the temperature rises, so that the melting by the non-consumable electrode arc becomes smooth and the formation of the weld end part bead becomes smoother. . Furthermore, the generation of spatter from the consumable electrode can be further suppressed.

  According to the third aspect of the invention, in addition to the effects of the first and second aspects of the invention, at the end of the crater process, the supply of the consumable electrode is stopped and then delayed to extinguish the non-consumable electrode arc. Therefore, it is possible to prevent the consumable electrode from being welded to the molten pool.

  According to the fourth aspect of the invention, in addition to the effects of the first and second aspects, at the end of the crater process, the consumable electrode is reversely fed and then stopped, and at the same time or delayed, the non-consumable electrode arc is generated. By extinguishing the arc, welding of the consumable electrode to the molten pool can be prevented. Since the tip of the consumable electrode can be reliably pulled away from the molten pool by reverse feeding of the consumable electrode, welding can be prevented more reliably.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
FIG. 1 is a configuration diagram of a welding apparatus for carrying out a crater treatment method for two-electrode arc welding according to Embodiment 1 of the present invention. Hereinafter, each configuration will be described with reference to FIG.

  The welding start circuit ST outputs a welding start signal St for instructing the start / end of welding. This welding start circuit ST is built in a programmable logic controller (PLC), a robot controller or the like in robot welding. When the welding start signal St becomes a high level, welding is started, and when the welding start signal St becomes a low level, the welding is finished after shifting to a crater process. The consumable electrode arc welding power source PSM outputs the consumable electrode arc welding voltage Vwm and the consumable electrode arc welding current Iwm and controls the rotation of the wire feed motor WM when the welding start signal St is at a high level. The feed control signal Fc is output. When the welding start signal St changes to the Low level, the consumable electrode arc welding power source PSM stops outputting after shifting to the crater process. The non-consumable electrode arc welding power source PSP outputs the non-consumable electrode arc welding current Iwp and the non-consumable electrode arc welding voltage Vwp when the above-mentioned welding start signal St becomes High level. When the welding start signal St changes to the Low level, the non-consumable electrode arc welding power source PSP stops outputting after shifting to the crater process. The crater process will be described later with reference to FIG. Since the consumable electrode arc welding power source PSM is controlled at a constant voltage, the consumable electrode arc welding voltage Vwm is controlled to be equal to a predetermined welding voltage setting signal. Further, since the non-consumable electrode arc welding power source PSP is controlled at a constant current, the non-consumable electrode arc welding current Iwp is controlled to be equal to a predetermined welding current setting signal.

  The structure of the welding torch is as follows. A power supply tip 41 is provided at the coaxial central portion, and the consumable electrode 11 fed by the feed roll 5 coupled to the wire feed motor WM is fed when fed through the power feed tip. The The consumable electrode 11 is fed at a wire feed speed Fw. The non-consumable electrode 12 has a substantially cylindrical shape and has a hollow structure. The consumable electrode 11 is fed through the insulated hollow space, and a consumable electrode arc 31 is generated between the base metal 2 and the consumable electrode 11. A plasma nozzle 42 is provided outside the non-consumable electrode 12, and a plasma gas 61 flows inside the plasma nozzle 42. Further, a shield gas nozzle 43 is provided on the outer side, and the shield gas 62 flows on the inner side. A thermally constrained non-consumable electrode arc 32 is generated between the non-consumable electrode 12 and the base material 2.

  FIG. 2 is a timing chart of each signal in the welding apparatus described above with reference to FIG. 1 for illustrating a crater processing method for two-electrode arc welding according to Embodiment 1 of the present invention. (A) shows the welding start signal St, (B) shows the wire feed speed Fw, (C) shows the welding electrode arc welding voltage Vwm, and (D) shows the wear. The electrode arc welding current Iwm is shown, FIG. 5E shows the non-consumable electrode arc welding voltage Vwp, and FIG. 8F shows the non-consumable electrode arc welding current Iwp. Hereinafter, a description will be given with reference to FIG.

  Prior to time t1, as shown in FIG. 5A, since the welding start signal St is at a high level, a steady welding period is reached. During this period, the consumable electrode 11 is fed at a steady wire feed speed as shown in FIG. 5B, and the steady consumable electrode arc welding voltage Vwm is set as shown in FIG. As shown in FIG. 4D, a steady welding electrode arc welding current Iwm is energized. Further, as shown in FIG. 5E, a steady non-consumable electrode arc welding voltage Vwp is applied, and as shown in FIG. 5F, a steady non-consumable electrode arc welding current Iwp is energized.

  When the welding torch 4 reaches the welding end position at time t1, the welding start signal St changes to the low level as shown in FIG. In response to this, during the predetermined first crater processing period Tc1, the wire feeding speed Fw is set to a value smaller than the steady welding period, as shown in FIG. It is sent in Fcw. The consumable electrode arc welding voltage Vwm and the consumable electrode arc welding current Iwm stop outputting as shown in FIGS. Therefore, the consumable electrode arc 31 is extinguished at time t1.

  During the second crater processing period Tc2 determined from the time t1, the welding current Iwp for the non-consumable electrode arc is set to a value smaller than the steady welding period, as shown in FIG. Change to Icp to energize. As shown in FIG. 5E, the non-consumable electrode arc welding voltage Vwp is a crater welding voltage value Vcp corresponding to the crater welding current value Icp. Therefore, the non-consumable electrode arc 32 continues in a state where the crater welding current value Icp is energized.

  The first crater processing period Tc1 is set shorter than the second crater processing period Tc2. Therefore, during the first crater processing period Tc1 between times t1 and t2, the consumable electrode arc 31 is extinguished, the consumable electrode 11 continues to be fed, and the non-consumable electrode arc 32 is maintained. Crater processing is performed in this state. Since the consumable electrode 11 is stably melted by the non-consumable electrode arc 32, no spatter is generated even if the consumable electrode 11 is short-circuited with the molten pool. Further, since the consumable electrode arc 31 is extinguished and the current value of the non-consumable electrode arc 32 is also small, an excessive arc force does not act on the molten pool, and a sound weld end bead can be obtained. Can be formed.

  When the first crater processing period Tc1 ends at time t2, the wire feed speed Fw becomes 0 and stops as shown in FIG. On the other hand, as shown in FIG. 5F, the non-consumable electrode arc welding current Iwp stops after energization is continued until time t3. The end control of the crater process at times t2 to t3 is control for preventing the consumable electrode 11 from being welded to the molten pool. The consumable electrode 11 whose feeding has been stopped is melted by the non-consumable electrode arc 32 and welded. To prevent.

  According to the first embodiment described above, at the end of welding, the consumable electrode arc is extinguished while the supply of the consumable electrode is continued, and the consumable electrode is melted by the non-consumable electrode arc to perform crater processing. For this reason, since the consumable electrode is stably melted by the non-consumable electrode arc, it is possible to prevent the occurrence of sputtering. Furthermore, since the crater treatment is performed only with the non-consumable electrode arc, the arc force to the molten pool is weakened, and a sound weld end portion bead can be formed.

  Further, at the end of the crater process, welding of the consumable electrode can be prevented by delaying the supply of the consumable electrode and then extinguishing the non-consumable electrode arc.

[Embodiment 2]
FIG. 3 is a timing chart showing a crater processing method for two-electrode arc welding according to Embodiment 2 of the present invention. The figure corresponds to FIG. 2 described above, and the signals in FIGS. Since this figure differs from FIG. 2 only in the operation at times t2 to t3, this period will be described with reference to the figure.

  When the first crater processing period Tc1 ends at time t2, the wire feed speed Fw starts reverse feed at the reverse feed speed Fbw as shown in FIG. Reverse feed refers to feed in which the consumable electrode 11 is pulled back in a direction away from the base material. Then, when the second crater processing period Tc2 ends at time t3, the supply of the consumable electrode 11 is stopped as shown in FIG. 5B, and the non-consumable electrode arc is used as shown in FIG. The energization of the welding current Iwp is stopped and the non-consumable electrode arc 32 is extinguished. Here, the extinguishing timing of the non-consumable electrode arc 32 may be delayed from the time t3. During the period from time t2 to time t3, the consumable electrode 11 is reversely fed, and the non-consumable electrode arc 32 is continued to prevent welding of the consumable electrode 11 and the molten pool.

  According to the above-described second embodiment, at the end of the crater process, the consumable electrode is prevented from being welded by stopping the consumable electrode after it is fed back and stopping at the same time or by delaying the non-consumable electrode arc. can do. Since the tip of the consumable electrode can be reliably pulled away from the molten pool by reverse feeding of the consumable electrode, welding can be prevented more reliably.

[Embodiment 3]
FIG. 4 is a timing chart showing a two-electrode arc welding crater processing method according to Embodiment 3 of the present invention. This figure corresponds to FIGS. 2 and 3 described above, and the signals in FIGS. 2A to 2F are the same. Hereinafter, operations different from those in FIGS. 2 and 3 will be described with reference to FIG.

  In the present embodiment, during the first crater processing period Tc1 between times t1 and t2, the consumable electrode 11 is short-circuited with the molten pool, and the heating current Ihm is applied as shown in FIG. By applying the heating current Ihm, the consumable electrode arc welding voltage Vwm becomes the heating voltage value Vhm as shown in FIG. Even in this case, the consumable electrode arc 31 is extinguished at time t1. For this reason, the consumable electrode 11 is short-circuited with the molten pool, and the heating voltage Vhm is set to a low value at which no arc can be generated. For preventing the welding at the end of the crater process, the method of either Embodiment 1 or 2 is performed. This figure shows the case of the welding prevention method of the second embodiment.

  According to Embodiment 3 described above, during the crater treatment, the tip of the consumable electrode is short-circuited with the molten pool, and a heating current is applied to the consumable electrode. For this reason, since the consumable electrode is heated and the temperature rises, the melting by the non-consumable electrode arc becomes smooth, and the formation of the welding end part bead becomes smoother. Furthermore, it is possible to further prevent spatter from the consumable electrode.

It is a block diagram of the welding apparatus for enforcing the crater processing method of the two-electrode arc welding which concerns on Embodiment 1 of this invention. It is a timing chart which shows the crater processing method of the two-electrode arc welding which concerns on Embodiment 1 of this invention. It is a timing chart which shows the crater processing method of the two-electrode arc welding which concerns on Embodiment 2 of this invention. It is a timing chart which shows the crater processing method of the two-electrode arc welding which concerns on Embodiment 3 of this invention. It is a schematic diagram which shows the structure and arc generating part of the welding torch in the two-electrode arc welding method of a prior art.

Explanation of symbols

2 Base material 4 Welding torch 5 Feed roll 11 Consumable electrode 12 Non-consumable electrode 21 Molten pool 31 Consumable electrode arc 32 Non-consumable electrode arc 41 Feed tip 42 Plasma nozzle 43 Shield gas nozzle 61 Plasma gas 62 Shield gas Fbw Reverse feed speed Fc Feed control signal Fcw Crater feed speed Fw Wire feed speed Icp Crater welding current Ihm Heating current Iwm Consumable electrode arc welding current Iwp Non-consumable electrode arc welding current PSM Consumable electrode arc welding power supply PSP Non-consumable electrode arc Welding power supply ST Welding start circuit St Welding start signal Tc1 First crater processing period Tc2 Second crater processing period Vcp Crater welding voltage value Vhm Heating voltage Vwm Consumable electrode arc welding voltage Vwp Non-consumable electrode arc welding voltage WM Wire feed motor

Claims (4)

Crater treatment of two-electrode arc welding in which welding is performed by generating a consumable electrode arc and a non-consumable electrode arc using a welding torch having a consumable electrode and a non-consumable electrode disposed in a shield gas nozzle for discharging a shield gas In the method
At the end of welding, the consumable electrode arc is extinguished while continuing to feed the consumable electrode, and the consumable electrode is melted by the non-consumable electrode arc to perform crater treatment.
A crater treatment method for two-electrode arc welding. During the crater treatment, the tip of the consumable electrode is short-circuited with the molten pool, and a heating current is applied to the consumable electrode.
The crater treatment method for two-electrode arc welding according to claim 1. At the end of the crater process, the supply of the consumable electrode is stopped and then delayed to extinguish the non-consumable electrode arc.
The crater treatment method for two-electrode arc welding according to claim 1 or 2. At the end of the crater process, the consumable electrode is stopped after being reversely fed, and the non-consumable electrode arc is extinguished simultaneously or delayed.
The crater treatment method for two-electrode arc welding according to claim 1 or 2.

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