JP2011224587A - Insert-chip, plasma torch and plasma welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further increase the speed of plasma arc welding by a stable arc without causing hot cracking nor undercut.SOLUTION: The insert-chip 1 includes: a leading electrode space 1a, one or more intermediate electrode spaces 1b and a tail electrode space 1c; and three or more openings 4a, 4b, 4c which are distributed on one line in a welding direction y, respectively communicate with the respective electrode spaces and are opened oppositely to a welding line parallel to the one line. The plasma torch includes a plurality of electrodes 2a, 2b, 2c each having a tip part inserted in the corresponding electrode space of the insert-chip. The plasma welding device includes: first power sources 18ap, 18aw for feeding preheating power to the leading electrode 2a; second power sources 18bp, 18bw for feeding back bead formation power to the intermediate electrode 2b; and third power source 18cp, 18cw for feeding power for welding without welding rod to the tail electrode 2c. In the plasma welding device, a back bead is formed by a plasma arc of the leading electrode or the intermediate electrode, and preheating or welding without welding rod is performed by TIG arcs of the other electrodes.

Description

  The present invention relates to an insert tip of a plasma torch, a plasma torch using the insert tip, and a plasma welding apparatus using the plasma torch.

  Patent Document 1 describes a nozzle shape that improves the cross-sectional shape of a keyhole by plasma keyhole welding. Patent Document 2 describes simultaneous tanning welding by each torch in which two arc welding torches are arranged so that the arrangement of electrode tips is orthogonal to the welding line direction so as to form one molten pool. Has been. Patent Document 3 describes a composite welding method in which keyhole welding is performed by irradiating a molten pool of 0 to 2 mm ahead of the arc welding target position with laser (FIGS. 4, 0024, 0025). Patent Document 4 describes a laser welding method in which non-penetrating welding is performed with a preceding first laser beam, and through-hole (keyhole) welding is performed with a second laser beam while focusing on a hole opening formed thereby.

JP-A-8-10957 JP-A-6-155018 JP 2004-298896 A JP 2008-126315 A Japanese Patent Application No. 2009-201304

The cross section of the plasma arc of the plasma arc welding by the conventional 1 torch is substantially circular. Since keyhole welding by plasma arc is impossible if the plate thickness is less than 3 mm, tanning welding (heat conduction type welding: plasma does not penetrate through the object to be welded) is adopted.
B) Undercut occurs,
B) Hot cracking due to wide beads is likely to occur. In high-speed welding, the current is a high current and a wide arc, so a wide, shallow bead shape is formed, and high temperature cracking is likely to occur during solidification.

  In the conventional plasma arc welding with one torch, when the speed of keyhole welding (plasma penetrates through the material to be welded) is increased with a plate thickness of 3 to 10 mm, the convex portion with a raised central portion and the underside with a lowered edge portion Since cutting is possible, speeding up is difficult. Although there is a one-pool speedup with two torches, torches must be tilted greatly to make a one-pool, and the arc is easily disturbed and unstable due to the attracting arc force and magnetic blown by tilting.

  In order to realize high-speed welding without hot cracking and undercut with a stable arc, the present inventor distributes two electrode arrangement spaces on the same diameter line and communicates with each electrode arrangement space, respectively. And an insert tip provided with two nozzles opened opposite to a welding line parallel to the surface, and a plasma torch equipped therewith (Patent Document 5).

  According to this plasma torch, one pool 2 arc welding can be performed in which one arc is formed by two arcs. In this case, since the cross section of the plasma arc becomes a heat source that is long and thin in the welding progress direction y, the bead width (x direction) with respect to the amount of heat is kept narrow, and hot cracking does not occur even if the speed is increased. Moreover, by setting it as one pool 2 arc, in plate | board thickness 3-10mm, a keyhole welding can be carried out by a preceding arc, and a wide tanning welding can be carried out by a subsequent arc, and a surface bead can be made flat. If the plate thickness is less than 3 mm, it is possible to carry out digging welding with a leading arc and flatten the front bead with a trailing arc.

  An object of the present invention is to make plasma arc welding faster with a stable arc without causing hot cracking or undercut.

  (1) Lead electrode arrangement space (1a), one or more intermediate electrode arrangement spaces (1b) and tail electrode arrangement space (1c), and each electrode arrangement space (1a, 1b , 1c) and three or more openings (4a, 4b, 4c) each opened in opposition to the welding line parallel to the straight line (1: FIG. 1).

  In addition, in order to make an understanding easy, the code | symbol of the corresponding element or the equivalent element of the Example which is shown in drawing and mentions later in parentheses is attached for reference by reference. The same applies to the following.

  According to the plasma torch equipped with the insert tip (1), one pool multi-arc welding in which one molten pool is formed by three or more arcs can be performed. In this case, since the cross section of the plasma arc becomes a heat source that is long and thin in the welding progress direction y, the bead width (x direction) with respect to the amount of heat is kept narrow, and hot cracking does not occur even if the speed is increased. Also, by using a one-pool multi-arc, when the plate thickness is 3 to 10 mm, the welding line is preheated with the leading arc, the back beat by the keyhole is formed with the intermediate arc, and the front bead is formed by wide tanning welding with the trailing arc. It can be formed flat. If the plate thickness is less than 3 mm, the welding line can be preheated by the leading arc, the back bead can be formed by digging welding by the intermediate arc, and the front bead can be flattened by the trailing arc. In any case, since the back bead formation by the intermediate arc is facilitated by the preheating of the leading arc, high-speed welding can be performed while forming a good back bead.

It is the longitudinal cross-sectional view and block diagram of the welding apparatus using the plasma torch of 1st Example of this invention. (A) is the longitudinal cross-sectional view of the plasma torch of FIG. 1, (b) is the bottom view seen from the plasma injection end part side. 1 is an enlarged view of the insert tip 1 of the plasma torch of the first embodiment shown in FIG. 1, (a) is a front view, (b) is a longitudinal sectional view taken along line 3B-3B in (c), and (c). Is a bottom view. It is a longitudinal cross-sectional view of the plasma torch shown in FIG. 1, (a) shows the outline | summary of the pipe line which supplies plasma gas to each electrode accommodation space, (b) is the flow path of the cooling water which cools the insert chip 1 The outline of is shown. It is a cross-sectional view which shows typically the weld bead section in welding using the plasma torch of the present invention, (a) is a bead shape formed by preheating of a leading arc, (b) is a high-speed keyhole by an intermediate arc (C) shows the bead shape of tanning welding by a tail arc. It is an expanded sectional view which shows typically the behavior of a plasma arc at the time of the one pool 3 arc welding by the welding apparatus shown in FIG. It is the longitudinal cross-sectional view and block diagram of the welding apparatus using the plasma torch of 2nd Example of this invention. It is the longitudinal cross-sectional view and block diagram of the welding apparatus using the plasma torch of 3rd Example of this invention. It is the longitudinal cross-sectional view and block diagram of the welding apparatus using the plasma torch of 4th Example of this invention.

  (2) The intermediate electrode arrangement space (1b) and the tail electrode arrangement space (1c) are determined from the distance between the openings (4a, 4b) communicating with the leading electrode arrangement space (1a) and the intermediate electrode arrangement space (1b). The insert tip (1: FIG. 7) according to the above (1), wherein the distance between the openings (4b, 4c) communicating with the contact is long.

  (3) The insert tip according to (1) or (2), wherein the opening is a plasma arc nozzle (1: form 1).

  (4) The opening communicating with the head electrode arrangement space (1a) or the tail electrode arrangement space (1c) is a hole through which the TIG welding electrode passes, and the other opening is a plasma arc nozzle. The insert tip according to (2) (1: form 2/4).

  (5) The opening communicating with the leading electrode arrangement space (1a) and the trailing electrode arrangement space (1c) is a hole through which the TIG welding electrode passes, and the opening communicating with the intermediate electrode arrangement space (1b) is a plasma arc. The insert tip according to (1) or (2), which is a nozzle (1: form 3).

  (6) The opening communicating with the head electrode arrangement space (1a) is a plasma arc nozzle, and the opening communicating with the intermediate electrode arrangement space (1b) and the tail electrode arrangement space (1c) is penetrated by a TIG welding electrode. The insert tip according to (1) or (2), which is a hole (1: form 5).

  (7) The insert tip (1) according to the above (1) and a plurality of electrodes (2a, 2b, 1b) having respective tip portions inserted into the electrode arrangement spaces (1a, 1b, 1c) of the insert tip (1) A plasma torch comprising 2c).

  (8) The plasma torch described in (7) above, the first power supply (18ap, 18aw) for supplying preheating power to the leading electrode (2a) of the plasma torch, and the back bead forming power to the intermediate electrode (2b) A plasma welding apparatus comprising: a second power source (18bp, 18bw) for feeding power; and a third power source (18cp, 18cw) for feeding tanning power to the tail electrode (2c).

  (9) a plasma torch comprising a plurality of electrodes (2a, 2b, 2c) each having a tip inserted into each electrode arrangement space (1a, 1b, 1c) of the insert tip (1) described in (2) above; A first power source (18ap, 18aw) for supplying preheating power to the leading electrode (2a) of the plasma torch, a second power source (18bp, 18bw) for supplying keyhole welding power to the intermediate electrode (2b), and a tail electrode And a third power source (18cp, 18cw) for supplying tanning power to (2c).

  (10) The plasma welding apparatus according to the above (8) or (9), wherein the opening of the insert tip is a plasma arc nozzle, and the first, second and third power sources are plasma welding power sources. ).

  (11) The opening of the insert tip that communicates with the leading electrode arrangement space (1a) or the trailing electrode arrangement space (1c) is a hole through which the TIG welding electrode passes, and the other opening is a plasma arc nozzle, The plasma welding apparatus according to (8) or (9), wherein the first power source or the third power source is a TIG welding power source and the other power source is a plasma welding power source (mode 2/4).

  (12) The opening of the insert tip that communicates with the head electrode arrangement space (1a) and the tail electrode arrangement space (1c) is a hole through which the TIG welding electrode passes, and communicates with the intermediate electrode arrangement space (1b). The plasma welding apparatus according to the above (8) or (9), in which the opening is a plasma arc nozzle, the first power source and the third power source are TIG welding power sources, and the second power source is a plasma welding power source. ).

  (13) The opening of the insert tip communicating with the leading electrode arrangement space (1a) is a plasma arc nozzle, and the opening communicating with the intermediate electrode arrangement space (1b) and the trailing electrode arrangement space (1c) is TIG. The plasma welding apparatus according to (8) or (9) above, wherein the welding electrode is a hole through which the first power source is a plasma welding power source and the second and third power sources are TIG welding power sources. 5).

  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

-1st Example-
FIG. 1 shows a plasma welding apparatus according to the first embodiment, FIG. 2 (a) shows only the plasma torch shown in FIG. 1, ie, the plasma arc torch of the first embodiment, and FIG. Indicates the tip of the torch. The plasma arc torch of the first embodiment is of a form that performs plasma welding. The insert chip 1 is fixed to the insulating base 9 by screwing the insert cap 7 to the insulating base 9. The shield cap 8 is fixed to the insulating table 9 by screwing. The head electrode base 11, the intermediate electrode base 12, and the tail electrode base 13 separated in the x direction by being divided into three are inside an outer case 30 made of an insulator. The stem of the insulating body 14 passes through the space between the intermediate electrode base 12 and the leading and trailing electrode bases 11 and 13.

  The insert tip 1 is distributed on the same diameter line orthogonal to the center axis (z) of the tip and is equidistant from the center axis, leading and trailing electrode arrangement spaces 1a and 1c, and an intermediate electrode arrangement at the center axis position. There is a space 1b, and in each electrode arrangement space, the leading ends of the leading electrode 2a, the intermediate electrode 2b, and the trailing electrode 2c that pass through the insulating table 9 and are fixed to the electrode tables 11 to 13 with screws 10a, 10b, and 10c are provided. The centering stone 3 is inserted and positioned at the axial center positions of the electrode arrangement spaces 1a to 1c. Nozzles 4 (4a, 4b, 4c) connected to the electrode arrangement spaces 1a to 1c are opened on the tip surface of the insert tip 1 facing the base material 16 (material to be welded).

  FIG. 3 shows the insert chip 1 in an enlarged manner. The insert tip 1 of the present embodiment is distributed on the same diameter line perpendicular to the central axis (z) of the tip 1 and is equidistant from the central electrode arrangement space 1b located at the central axis. Front and rear electrode arrangement spaces 1a and 1c extending parallel to the central axis (z), and front, middle, and rear nozzles 4a that communicate with the spaces 1a, 1b, and 1c and open at a front end surface facing the base material 16, 4b, 4c. In the present embodiment, these nozzles 4a, 4b, and 4c are also distributed on the same diameter line orthogonal to the central axis (z) of the chip, and are distributed at an equal pitch parallel to the central axis.

  Although not shown in FIG. 1, the torch insulating base 9 includes a pilot gas passage and a cooling water passage shown in FIG. 4. In addition, there is a shield gas flow path (not shown) for guiding shield gas into the shield cap 8. As shown in FIG. 4A, the pilot gas enters the electrode arrangement spaces 1a to 1c through the gas flow path and the electrode insertion space, becomes plasma at the electrode tip, and passes through the nozzles 4a to 4c. Erupts from the tip of As shown in FIG. 4B, the cooling water enters the space between the outer peripheral surface of the insert tip 1 and the inner peripheral surface of the insert cap 7 through the cooling water supply channel, and from there the cooling water Go out of the torch through the drainage channel. The shield gas passes through the shield gas flow path, enters the cylindrical space between the insert cap 7 and the shield cap 8, and is ejected from the tip of the torch.

  As shown in FIG. 1, pilot arcs are generated between the electrodes 2a, 2b, 2c and the tip 1 by the pilot power supplies 18ap, 18bp, 18cp, and between the electrodes 2a, 2b, 2c and the base material 16, When a welding arc (plasma arc) is generated by a plasma power source 18aw (for preheating), 18bw (for back bead formation), 18cw (for tanning welding) in which the electrode side is negative and the base metal side is positive. A plasma arc current flows between each electrode 2a, 2b, 2c and the base material 16, and 1 pool 3 arc welding is implement | achieved. In the welding apparatus shown in FIG. 1, preheating by the plasma arc of the electrode 2a, back bead formation by the electrode 2b, and tanning by the electrode 2c are performed. In addition, the advancing direction of welding is an arrow y direction. That is, the surface part molten pool (FIG. 5 (a)) generated by the leading preheating is such that the intermediate bead formation melts or penetrates to the base material back surface (bottom surface) (FIG. 5 (b)), and 3 mm In the case of the above thick plates, for example, a molten pool formed by keyhole welding is fed backward, and a molten bead formed by keyhole welding is leveled by subsequent tanning welding. As a result, a tanned weld bead smoothly connected to the base material surface shown in FIG. In the case of a thin plate of less than 3 mm, since keyhole welding is impossible, the bead shown in FIG. 5B is formed by leading preheating and intermediate welding, and this is formed by tail tanning welding in FIG. Change to the bead shown in c). Unlike conventional high-current one-pool wide welding, it is divided into functions for both the middle and rear, and high-speed welding with a narrow bead width can be performed with the minimum current required. Since the intermediate welding easily reaches the back surface of the base material by the preheating at the beginning, the welding can be performed at a higher speed.

  In the embodiment shown in FIG. 1, in the preheating with the leading electrode 2a, the pilot gas flow rate is reduced to 0.2 to 1.0 (liter / min), and preheating is performed with shallow penetration. In the formation of the back bead by the intermediate electrode 2b, the pilot gas flow rate is increased to 0.5 to 5.0 (liter / min) in order to deepen the penetration, and when the base metal thickness is 3 mm or more, the pilot gas with a high flow rate is formed by keyhole welding. In order to form a back wave, the base material is penetrated until it penetrates the back surface. If the thickness of the base material is less than 3 mm, a back bead (FIG. 5B) is formed by heat melting up to the back surface of the base material as a relatively low flow rate pilot gas. In the formation of the front bead by the tail electrode 2c, the pilot gas flow rate is reduced to 0.2 to 1.0 (liter / min), and the surface is melted and smoothed by shallow penetration ((c) in FIG. 5).

  For example, in 1 pool 2 arc welding presented in Patent Document 5, a base material having a plate thickness of 1.6 mm is comparatively 2.3 m / min under conditions of a leading arc current 210A and a trailing arc 210 / 160A: 30 Hz switching. High-speed and stable high-quality plasma arc welding can be performed. On the other hand, in this example, a base material having a plate thickness of 1.6 mm is 3.0 m / min under the conditions of a leading arc current 200A, an intermediate arc current 210A, and a trailing arc current 210 / 160A (45 Hz switching). High-speed and stable high-quality plasma arc welding can be performed.

  In general, two paths of current (plasma arc) flowing in parallel generate magnetic fluxes that rotate around the path, and these two directions are opposite in the direction of flow of the magnetic flux, so they cancel each other out, and the resultant magnetic flux is It goes around the outside of the two paths. The Lorentz force F acts on the two currents (plasma arc) due to the interaction between the magnetic field of the combined magnetic flux and the two-path currents, and the two currents (plasma arc) bend in a direction approaching each other. If the arc becomes unstable and the bending becomes large and two currents intersect, that is, if they merge, the originally intended welding characteristics will not be exhibited. That is, poor welding or poor bead shape occurs. This tendency increases as the current increases.

  However, in the embodiment shown in FIG. 1, as shown in FIG. 6, an attractive Lorentz force Fa acts between the arcs of the leading electrode 2a and the intermediate electrode 2b, but also between the arcs of the intermediate electrode 2b and the trailing electrode 2c. The attracting Lorentz force acting as Fc acts, and the combined force of Fa and Fc acts on the arc of the intermediate electrode 2b. The arc of the intermediate electrode 2b to be formed is stabilized, and the formation of a back wave (back bead) is stabilized. The Lorentz force Fa acting on the preheating arc of the leading electrode 2a swings the arc downstream in the welding progress direction y, and the arc has a backward angle with respect to the welding progress direction y, but does not affect the bead formation. The Lorentz force Fc acting on the tanning arc of the tail electrode 2c swings the arc upstream in the welding progress direction y, and the arc becomes an advance angle with respect to the welding progress direction y, thereby contributing to smoothing. That is, since the plasma of the tanning arc of the tail electrode 2c flows forward and the arc plasma does not disturb the molten pool formed behind the arc, the front bead has a smooth and clean bead surface.

-Second Example-
FIG. 7 shows a plasma welding apparatus according to a second embodiment of the present invention suitable for high-speed welding of thick plates. In keyhole welding in which the plate thickness is 3 mm or more and the pilot gas flow rate is increased, if the welding speed is increased, the molten pool by the intermediate electrode 2b becomes larger in the welding direction y, and the possibility that the molten metal melts increases. Therefore, in the second embodiment, the distance of the tail electrode 2c with respect to the intermediate electrode 2b is made longer than the distance between the leading electrode 2a and the intermediate electrode 2b, and the molten pool formed by the keyhole welding of the intermediate electrode 2b starts to solidify. The position is tanned and welded with a plasma arc of the tail electrode. Thereby, even if the keyhole welding speed is increased, molten metal can be prevented from being melted. The tanning welding by the tail electrode 2c is to reheat and melt the solidified metal. However, since the solidified metal has high heat immediately after the start of solidification, it is easily melted and adapted to high speed.

  Preheating or tanning can be performed not only by plasma arc welding but also by TIG welding. Since TIG welding does not require a pilot power supply, the power supply device can be configured at low cost. Further, since the shielding gas fills the lower end of the torch, the pilot gas ejected from the electrode arrangement space to the base material can be omitted in TIG welding. Therefore, the plasma welding apparatus of the present invention implements the welding forms shown in the following Table 1.

  In Embodiment 1 on Table 1, as in the first and second examples, all of the head electrode 2a, the intermediate electrode 2b, and the tail electrode 2c perform plasma arc welding.

-Third Example-
The plasma welding apparatus of the third example of the present invention shown in FIG. 8 is that of Embodiment 2 on Table 1. That is, the leading electrode 2a preheats the base metal by TIG welding, and protrudes further downward from the opening of the electrode arrangement space opened at the lower end surface of the insert tip 1, and the surface of the base metal by the TIG arc Preheat and melt. The intermediate electrode 2b and the tail electrode 2c are subjected to back bead formation and tanning by plasma arc welding as in the first and second embodiments.

-Fourth embodiment-
The plasma welding apparatus of the fourth example of the present invention shown in FIG. 9 is that of Embodiment 3 on Table 1. That is, the leading electrode 2a and the trailing electrode 2c are for preheating and tanning the base material by TIG welding, projecting further downward from the opening of the electrode arrangement space opened at the lower end surface of the insert tip 1, The surface of the base metal is preheated and welded by arcing. The intermediate electrode 2b performs back bead formation by plasma arc welding as in the first and second embodiments.

  In Embodiment 4 on Table 1, the tail electrode 2c is for tanning the base material by TIG welding, and further protrudes downward from the opening of the electrode arrangement space opened at the lower end surface of the insert tip 1, The surface of the base metal is tanned and welded with a TIG arc. As with the first and second embodiments, the leading electrode 2a and the intermediate electrode 2b are preheated and back-beaded by plasma arc welding.

  In Embodiment 5 on Table 1, the back bead is formed by plasma arc welding of the leading electrode 2a. The intermediate electrode 2b and the tail electrode 2c each form a front bead by TIG welding. That is, a front bead is formed in two stages. This is suitable for a base material having a large surface tension of the molten metal of the base material. In the fourth embodiment as well, the back bead can be formed by plasma arc welding of the leading electrode 2a, and the front bead can be formed by plasma arc welding by the intermediate electrode 2b and TIG welding by the tail electrode 2c.

  In each of the above-described examples and embodiments, there is one intermediate electrode 2b. However, according to the present invention, there is an aspect in which two or more intermediate electrodes are used. However, also in this case, all the electrodes are on a straight line extending in the welding direction. For example, in the embodiment using two intermediate electrodes 2b1 and 2b2, a thick base material that cannot be penetrated to the back surface of the base material by keyhole welding with one intermediate electrode is removed by plasma arc welding with the preceding intermediate electrode 2b1. Then, keyhole welding can be performed up to the back surface of the base material by plasma arc welding using the subsequent intermediate electrode 2b2. In other words, the thick plate can be keyhole welded at high speed.

1: Insert tip 1a, 1b, 1c: Lead, middle, and tail electrode arrangement space 2 (2a, 2b, 2c): Electrode 2a: Lead electrode 2b: Intermediate electrode 2c: Trail electrode 3: Centering stone 4 (4a, 4b) , 4c): Nozzle (head, middle and tail nozzles)
7: Insert cap 8: Shield cap 9: Insulation base 10 (10a, 10b, 10c): Electrode fixing screw 11: Lead electrode base 12: Intermediate electrode base 13: Rear electrode base 14: Insulation body 16: Base materials 18, 43 : Power supply 19: Plasma 20: Pool 30: Outer case

Claims (13)

  The first electrode arrangement space, the one or more intermediate electrode arrangement spaces, and the rear electrode arrangement space are distributed on a straight line in the welding direction, and communicate with each electrode arrangement space, respectively, and open to face a welding line parallel to the straight line. An insert chip comprising at least one opening.   The insert tip according to claim 1, wherein a distance between the openings communicating with the intermediate electrode arrangement space and the rear electrode arrangement space is longer than a distance between the openings communicating with the leading electrode arrangement space and the intermediate electrode arrangement space. .   The insert tip according to claim 1, wherein the opening is a plasma arc nozzle.   The insert tip according to claim 1 or 2, wherein the opening communicating with the head electrode arrangement space or the tail electrode arrangement space is a hole through which the TIG welding electrode passes, and the other opening is a plasma arc nozzle.   The opening communicating with the head electrode arrangement space and the tail electrode arrangement space is a hole through which a TIG welding electrode passes, and the opening communicating with the intermediate electrode arrangement space (1b) is a plasma arc nozzle. Insert chip as described in.   The opening that communicates with the head electrode arrangement space is a plasma arc nozzle, and the opening that communicates with the intermediate electrode arrangement space and the tail electrode arrangement space is a hole through which a TIG welding electrode passes. Insert tip.   A plasma torch comprising: the insert tip according to claim 1; and a plurality of electrodes each having a tip portion inserted into each electrode arrangement space of the insert tip.   8. The plasma torch according to claim 7, a first power source for supplying preheating power to the leading electrode of the plasma torch, a second power source for supplying back bead forming power to the intermediate electrode, and tanning power to the tail electrode And a third power source.   A plasma torch comprising a plurality of electrodes each having a tip inserted into each electrode arrangement space of the insert tip according to claim 2, a first power source for supplying preheating power to the leading electrode of the plasma torch, and a key for the intermediate electrode A plasma welding apparatus comprising: a second power source for supplying hall welding power; and a third power source for supplying tanning power to a tail electrode.   The plasma welding apparatus according to claim 8 or 9, wherein the opening of the insert tip is a plasma arc nozzle, and the first, second, and third power sources are plasma welding power sources.   The opening of the insert tip that communicates with the head electrode arrangement space or the tail electrode arrangement space is a hole through which the TIG welding electrode passes, the other opening is a plasma arc nozzle, and the first power source or the third power source is TIG. The plasma welding apparatus according to claim 8 or 9, wherein the power source is a welding power source and the other power source is a plasma welding power source.   The opening of the insert tip that communicates with the head electrode arrangement space and the tail electrode arrangement space is a hole through which the TIG welding electrode passes, and the opening that communicates with the intermediate electrode arrangement space is a plasma arc nozzle, The plasma welding apparatus according to claim 8 or 9, wherein the third power source is a TIG welding power source and the second power source is a plasma welding power source.   The opening of the insert tip that communicates with the leading electrode arrangement space is a plasma arc nozzle, and the opening that communicates with the intermediate electrode arrangement space and the trailing electrode arrangement space is a hole through which the TIG welding electrode passes, and The plasma welding apparatus according to claim 8 or 9, wherein the one power source is a plasma welding power source and the second and third power sources are TIG welding power sources.

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