TWI554351B - Welding by the use of two electrodes plasma torch - Google Patents

Description

Welding method using two-electrode plasma torch

The invention relates to a welding method using a two-electrode plasma torch, which uses a two-electrode plasma torch, which is provided with an embedded tip, the embedded tip has two electrode arrangement spaces and is respectively connected to each electrode arrangement space. 2 nozzles; the arrangement direction of the two nozzles is parallel to the weld line, and at least one of the torch and the material to be welded is driven in the direction along the weld line, and each electrode is located in each electrode arrangement space A plasma arc is generated and the weld line is welded.

The cross section of a plasma arc using a conventional single electrode torch is generally circular. If the thickness is less than 3 mm, it is impossible to use the plasma arc for penetration welding. Therefore, although common welding (thermal conduction type welding) is used, if penetration welding and common welding are performed, as long as the speed is increased, 1) occurs. Depression, 2) If it is welded together, it will easily cause high temperature cracks due to wide joints. In the case of high-speed welding, since a wide current is formed by a high current in the current, the shape of the joint is wide and shallow, and high temperature cracking is likely to occur during solidification.

If the plasma arc welding of the conventional single-electrode torch is used, as long as the plate thickness is 3 to 10 mm, the penetration welding is accelerated, and the convex portion of the central portion is raised to form a depression in which the edge portion is lowered, so that it is difficult to perform. High speed. Although there is also a single-melting tank with two torches, the speed of the single-melting pool is increased. However, as a single-melting tank, it is necessary to increase the magnetic blow caused by the inclined arc forces that are inclined to each other, making the arc easy to be disordered and unstable. .

Therefore, the present inventors have provided the use of the embedded tip and the plasma torch using the same, and it is possible to achieve high-speed welding without high-temperature cracking or depression without stabilizing the arc (Patent Document 1). In the welding method of the formation of the osmotic wave, although there is penetration welding and common welding, However, for the convenience of the following description, the formation of the permeation wave is indicated by penetration welding.

The plasma torch of Patent Document 1 is an embedded tip and a plasma torch equipped with the tip to insert each electrode into each electrode arrangement space, the embedded tip having: 2 electrode arrangement spaces; and 2 nozzles They are distributed on the same straight line, respectively connected to the respective electrode arrangement spaces, and are relatively open to the weld lines parallel to the aforementioned diameter lines. According to the plasma torch, one molten pool can be formed by two torches, and the single arc of the single molten pool can be welded. The cross section of the plasma torch is an elongated heat source in the direction in which the welding is performed (y), so that the joint width (x direction) of heat is suppressed to be narrow, and high temperature cracking does not occur even if the speed is increased. In addition, by double-arcing in a single molten pool and re-melting using a post-plasma arc, the surface joints can be flattened (for common welding).

In the parallel welding using two plasma flames at a certain distance, a slightly similar effect can be obtained, but the arc interval in the direction of welding is widened, so if the workpiece is short welded (base metal: welding material) ), it is impossible to weld with the same path, it must be welded for double paths, and it is difficult to speed up. In addition, since the arc interval is wide, the trailing arc must melt the once solidified joint again, and high heat must be input in the subsequent welding. As long as the two-electrode plasma torch of Patent Document 1 is used, penetration welding and common welding can be performed at the same time, so that it is possible to perform one-time welding without time consuming, and, after cooling in a molten pool using penetration welding, common welding is performed. Therefore, as long as a small amount of welding heat is input, there is an energy saving effect.

However, if a double arc is used for plasma arc welding with one of the embedded prongs, the thermal load applied to the embedded tip becomes large. In order to achieve higher speed, it is necessary to increase the cooling capacity of the embedded tip.

Therefore, the inventors of the present invention provide a built-in tip having a high cooling capacity, and can perform welding without high-temperature cracks or depressions at a higher speed by stabilizing the arc (Patent Document 2). The embedded tip has: two electrode arrangement spaces; two nozzles respectively connected to the respective electrode arrangement spaces; and a V-type cooling water flow path at the middle point of the two nozzles The plane intersecting the plane of the two nozzle distributions returns the cooling water. Thereby, the cooling water is smoothly returned in the vicinity of the tip end surface (the opposing side of the base material), the water or the foam is not partially retained, and the cooling ability of the tip is high. The drilling is performed so as to incline the tip end face and intersect at the front end portion, whereby the V-type cooling water flow path can be formed at a low price. Therefore, the welding current can be increased to perform welding at a higher speed. Further, in Patent Document 2, the insertion tip is further provided, and the pair of nozzle members are detachably coupled to the tip base. According to this, when the nozzle portion at the lower end of the nozzle member is deformed or melted due to high heat, the nozzle member is replaced with a new one, and the tip base is still used, which can reduce the maintenance cost.

Further, in order to reduce the cost of replacement of the embedded tip, the inventors of the present invention provide an embedded tip having a central portion having a nozzle open, a stem connected to the umbrella, and a joint connected to the stem. The screw portion has a sealing material between the trunk portion and the male screw portion, and has an electrode arrangement space communicating with the nozzle therein, and two nozzle members can be attached and detached to the embedded tip base body (Patent Document 3). When the nozzle portion at the lower end of the nozzle member is deformed or melted due to high heat, the nozzle member is replaced with a new one, and the embedded tip base is still used, which can reduce maintenance costs.

However, if the arrangement direction of the two nozzles of the two-electrode plasma torch is parallel to the weld line, and at least one of the torch and the material to be welded is driven by the two-electrode plasma in the direction of the weld line, for example, As shown in Fig. 19(a), in the welding direction y (the direction in which the weld line extends), the plasma arc 19b generated as the electrode for the weld line, that is, the leading electrode (the electrode 12b inside the nozzle member 20b: Fig. 2) is used first. The surface of the upper end surface (melt line) between the welding target materials 31a and 31b is preheated, and the electrode for the weld line, that is, the rear row electrode (the inside of the nozzle member 20a) is used in the welding direction y. The electrode 12a: the plasma arc 19a produced in Fig. 2), in the state of penetration welding of the weld line, due to the distance corresponding to the nozzle member 20b of the preceding nozzle and the nozzle member 20a of the succeeding row and the nozzle angle of the welding direction y It The preheating time lag is likely to cause insufficient formation (residual) of the osmotic wave due to insufficient input heat at the beginning of the weld line. This input heat shortage (poor wave formation insufficient: residual) is as shown in Fig. 19 (b), and the higher the welding speed is.

In addition, for example, as shown in FIG. 18(a), in the welding direction y (the direction in which the weld line extends), the plasma arc generated for the leading electrode of the weld line is used first, and the weld line is penetrated and welded. In the state where the plasma arc generated by the rear pole is heated (co-welded), the molten metal of the molten pool formed by the prior penetration welding is sucked into the melting of the common fusion plasma arc. In the pool, between the penetration welding portion and the common welding portion A, the molten finance flows from the leading electrode side to the rear row electrode side, and the end portion is welded in the reduced thickness state after the welding line.

That is, if the welding of the two-electrode plasma torch is used, the welding end is likely to occur at the front end of the welding target material (the beginning of the welding line) and the rear end (the end of the welding line). If the continuous pipe is made by fusion, the welding end of the welding end and the terminal are not special problems, but in the case of short strip materials, the cutting end and the terminal not only make the raw material yield lower, but also The upper part is cut off, and the cost becomes high.

Therefore, the inventors of the present invention have used a two-electrode plasma torch, which has an embedded tip having two electrode arrangement spaces (2a, 2b) for improving the welding failure of the end of the material to be welded; And two nozzles are respectively connected to the respective electrode arrangement spaces; the arrangement direction of the two nozzles is parallel to the weld line, and at least one of the torch and the welding target material is driven while driving along the direction of the weld line. In the welding method of the two-electrode plasma torch, the welding arc is generated by each electrode located in each electrode arrangement space, and the welding method of the two-electrode plasma torch is used, suggesting (1) a welding method using a two-electrode plasma torch, the electrodes are One is used as a leading electrode (ie, a leading electrode) in the extending direction of the weld line, and is set to a plasma arc that generates a material for preheating the welding target, and the other of the electrodes is used as a trailing electrode (ie, the latter) a plasma arc that is set to be fused by the osmotic wave, and is set to be before the front end of the material to be welded after the osmotic wave is welded, and the plasmon arc is formed by the spur wave to form a spliced plasma arc. The plasma arc of the first step is started at the same time as or before the plasma arc that generates the osmotic wave to form the welding. When the plasma arc is started first or simultaneously, or after the start, the driving is started, when the poles are After the rear end of the material to be welded, the plasma arc of the leading and trailing poles is stopped; and (2) a welding method using a two-electrode plasma torch, one of the electrodes is advanced in the direction of the weld line The electrode (that is, the leading electrode) is set to a plasma arc in which the osmotic wave is fused, and the other of the electrodes is used as a trailing electrode (ie, a trailing electrode), and is set to a plasma arc for common welding of the fused wire. The plasma arc is formed by the priming of the osmotic wave to form a spliced plasma arc, and when the osmotic wave is formed to form a spliced plasma arc or at the front end of the spliced object material, the post-row is activated. Plasma arc, when the plasma arc is started first or simultaneously, or after the start, the driving is started, and the plasma arc of the leading and trailing poles is stopped when the poles are located behind the welding material (Patent Document) 4).

According to the above (1), although a preheating time lag corresponding to the distance between the leading/rearing poles is generated (Fig. 19(b)), there is no such preheated cold steel plate section, and the traveling drive is reduced. The speed can reduce the formation of poor penetration of the front end of the material to be welded. As long as the preheating time interval is exceeded, the steel plate in the rear row can be easily welded by the preheating effect of the leading electrode, and the traveling drive speed can be improved, and the productivity of welding can be improved. The rear end of the material to be fused is processed by a low-speed, low-current fusion interface, and the molten pool that is extended behind the osmotic wave forming an arc (for example, penetrating arc) by a high-speed, high-current, will flow into the rear melt. Pulling back to the back side of the permeation wave arc, thereby correcting the depression of the rear end surface to be flat, can reduce the back end defect. By these procedures, the raw material yield of the front end and the back end of the welding target material can be improved.

When the leading pole (for preheating) is located at the front end of the material to be welded, the plasma arc (preheating) is started at the leading pole (for preheating), thereby avoiding the pre-equivalent to the distance between the leading/rearing poles The thermal lag (Fig. 19(a)) causes poor penetration of the osmotic wave at the tip end of the welded target (Fig. 19(b)). As long as the penetration is formed by the trailing pole, the steel plate in the rear row can be easily welded by the preheating effect of the leading pole, and the traveling drive speed can be improved, whereby the productivity of welding can be improved. The rear end of the welding target material is processed by a low-speed, low-current fusion interface, and the molten pool which is extended behind the osmotic wave to form an arc after the high-speed, high-current is shortened, and the molten liquid flowing back into the rear is pulled back. The side of the wave is oscillated, whereby the recess of the rear end surface is corrected to be flat, and the back end defect can be reduced. By these procedures, the raw material yield of the front end and the back end of the welding target material can be improved.

According to the above (2), the front end of the material to be welded is handed to the rear end, and the stable plasma arc with less flow of the pilot gas and lower current is used, and the osmotic wave of the preceding wave forms the arc immediately behind. In the vicinity, only the surface is arc-melted, whereby the welded surface is subjected to common welding, and even if it is welded at a high speed, a surface seam having less depression can be obtained. As long as the trailing pole reaches the front end of the welding target material, the plasma arc current of the leading pole can be increased, and the traveling driving speed is increased, thereby reducing the residual of the penetration wave fusion at the tip end (Fig. 19(b)). Improve the productivity of welding.

However, the raw material yield of the front end and the rear end of the welding target material can be considerably improved, and the productivity of welding can be considerably improved, but the suppression of the rear end depression is improved, but it is expected to be further effectively suppressed. Therefore, after studying the generation of the back-end depression, the following findings are obtained.

In the plasma welding (steady state) of the two-electrode plasma torch 30 shown in Fig. 21 (a), although a magnetic flux which is rotated around the plasma arc is generated, the molten pool indicated by a broken line in the figure At a high temperature above the magnetic deformation temperature (about 730 ° C), the magnetic flux is not easily passed, so the magnetic flux that rotates around the plasma arc is shown in Fig. 21 (b), behind the rear pole (T). , far from the plasma flame. However, both electrodes flow plasma arc current, Therefore, the plasma flames (arc currents) of the two electrodes are mutually restrained, and the plasma flame of the trailing electrode (T) is drawn to the direction y of the welding. As shown in Fig. 21 (c), the weld seam is a non-recessed person.

However, the two-electrode plasma torch 30 becomes the rear end position of the welding target material, as shown in Fig. 22 (a), the leading pole (L) becomes forwarder than the rear end of the welding target material, as long as the arc of the preceding pole stops, winding The magnetic flux of the plasma arc of the rear row is generated by the plasma flame of the trailing pole as shown in Fig. 22(b). The plasma flame of the trailing pole disappears due to the traction of the plasma flame of the first pole, and is biased to the rear of the trailing pole (T) by the interaction with the magnetic flux that generates the self-plasma flame around the plasma flame. With the plasma flame deflected rearward, the center of the molten pool is pushed up. Thereby, the surface seam is elongated at the rear, so that the molten metal (melted metal) on both sides of the joint is attracted to the center of the joint, and the joint section is as shown in FIG. 22(c), and becomes a deep concave shape. . This depression is a problem because the strength of the welded portion is lowered.

However, on a continuous production line of steel products or steel members, the material to be welded (steel or steel members) is successively transferred to the fusion stage. For example, in the process of manufacturing a cylinder in which a flat plate is bent into a cylindrical shape, the front surface of the original flat plate bent into a cylindrical shape is welded to each other, and the front end joint for arc starting is temporarily welded before the respective cylinders are welded to increase the production process. Counting, reducing production efficiency and increasing production costs. When the welding arc is started without using the front end joint and the welding arc is started, when a single electrode welding torch is used, it may fail when the arc is started, and the shape of the seam at the beginning of the welding is likely to become defective. At this time, after the welding, there must be a post-engineering to cut off the beginning of the welding.

In particular, when the two-electrode plasma torch disclosed in Patent Document 1 is used, as shown in FIG. 30, the magnetic flux forming the plasma arc current is wound around the plasma arc PA-L (first) and thereafter. The external arc of the plasma arc PA-T (rear row) that is commonly welded is rotated, but the front end of the high-heat conductor, that is, the copper front end joint 113 abuts The tongue portion 113p of the welding start material end of the welding target material W has a low magnetic permeability. Therefore, if the tongue portion 113p is in contact with the welding start end range TP-A of the welding start end, the magnetic flux is concentrated on the rear plasma arc PA-T side. The magnetic flux density is higher, that is, the magnetic field is stronger. Thereby, the trailing plasma arc PA-T is strongly pushed toward the direction of the preceding plasma arc PA-L for lateral deflection, and the molten metal of the subsequent nozzle structure (20b) immediately below the molten pool is strongly pushed toward the same Direction, at the beginning of the fusion range TP-A, the weld seam is recessed. The welding is performed as long as the trailing plasma arc PA-T is separated from the welding start end range TP-A, and the magnetic flux immediately outside the rear plasma arc PA-T passes through the welded joint of the welding target material and has a high magnetic permeability immediately below. The solid part and the welded joint after hardening leave from the trailing plasma arc PA-T, so the magnetic field acting on the trailing plasma arc PA-T is reduced, and the transverse direction of the plasma arc PA-T becomes smaller, and the welding is performed. The seam becomes flat. When the above-mentioned depression of the welded joint at the beginning of the fusion is caused by the cylinder for ending the welding, a post-engineering is required to remove the depression.

It is generally known that in order to stably start the welding arc, the front end joint is contacted with the welding start end of the welding target material, and the welding torch is placed above the front end joint to start the welding arc. After the welding arc is started, the welding target material is relatively transferred to the welding torch. Alternatively, the welding target material is transferred to the welding torch, and the welding wire is welded (for example, Patent Document 5). Patent Document 5 discloses a multi-electrode welding device in which three welding torches are arranged in series, and arc starting is synchronized on the front end joint, and simultaneously transferred in the same direction, and parallel welding is performed in parallel.

[Previous Technical Literature] [Patent Document]

Patent Document 1: Japanese Patent Laid-Open No. 2011-50982

Patent Document 2: Japanese Special Publication No. 2012-130965

Patent Document 3: Japanese Special Publication No. 2012-157868

Patent Document 4: Japanese Patent No. 2011-243218

Patent Document 5: Japanese Special Publication No. 2012-61497

[Summary of the Invention]

A first object of the present invention is to further suppress the occurrence of depressions in the tail end of the material to be welded in the welding using the two-electrode plasma torch. A second object of the present invention is to further improve the welding failure of both end portions of the welding target material in the welding using the two-electrode plasma torch. According to a third aspect of the present invention, the front end joint can be easily attached and detached to the material to be welded, and the fourth object of the present invention is to improve the shape of the welded joint in the range of the welding start end.

(1) A welding method using a two-electrode plasma torch, which uses a two-electrode plasma torch (30), which is provided with an embedded tip (1), and the embedded tip (1) has two electrode arrangement spaces. (2a, 2b) and two nozzles (3a, 3b) respectively connected to the respective electrode arrangement spaces; the arrangement direction of the two nozzles is parallel to the weld line, and the two-electrode plasma torch and the welding target material (31a) And at least one of 31b) is driven while traveling along the direction of the weld line, and a plasma arc is generated by each non-consumable electrode (12a, 12b) located in each electrode arrangement space, and the weld line is welded. At a position immediately below the plasma flame, a water-cooled copper joint opened by a slit or a groove constitutes a rear end joint (39a, 39b) which is disposed at a rear end of the welding target material (31a, 31b) in the welding direction, at the weld line In the extending direction, the pre-heating plasma arc is generated by the leading non-consumable electrode (ie, the leading electrode), and the non-consumable electrode (ie, the rear electrode) is used to generate a penetrating plasma arc, or the leading electrode is used to generate a penetrating power. Plasma arc, using the rear pole to produce a common plasma arc, The trailing electrode ends the welding at the aforementioned rear end until the plasma arc is stopped, and the plasma arc of the leading electrode is continued (Fig. 7, Fig. 9, Fig. 11, Fig. 14, Fig. 16).

In addition, for the sake of easy understanding, the embodiment shown in the parentheses is shown in the following figure. References or corresponding matters of corresponding or equivalent elements are indicated by way of example. The same is true below.

The rear pole ends the welding at the rear end of the welding target material until the plasma arc is stopped, and the plasma arc is advanced, so that the welding of the welding target material is completed, and the plasma flame of the rear pole and the plasma flame of the leading pole are mutually By pinning, since the plasma flame of the row after the rear end does not cause rearward deflection (Fig. 20), at the rear end, the surface seam does not become slender at the rear, and the recess at the rear end portion disappears.

[Embodiment of the Invention]

(2) The welding method using the two-electrode plasma torch according to (1) above, wherein the plasma arc of the preceding and trailing poles is stopped when the welding of the rear end is terminated by the trailing pole Thereafter, the aforementioned travel drive is stopped (Fig. 7, Fig. 9, Fig. 11, Fig. 14, Fig. 16).

(3) The method of welding a two-electrode plasma torch according to the above (1), wherein the welding target material and the rear end joint are inclined in a posture in which a rear end of the welding target material is lower than a front end, and the walking is performed The drive is in a direction parallel to the weld line (Fig. 18(b)). When the material to be welded is set to be horizontal, at the end portion of the material to be welded, the molten metal of the molten pool generated by the formation of the plasma by the osmotic wave is sucked into the common fusion pool, and the joint at the rear end easily becomes thickened. In the state, the thicker and less viscous the metal is, the more pronounced the metal is. As in the present embodiment, as long as the material to be welded is tilted, the force toward the welding direction is applied to the molten metal of the molten pool by gravity, the suction is suppressed, and the thickness of the joint at the rear end is reduced, and the rear end is reduced. The seam surface of the part is flattened.

(4) The method of welding a two-electrode plasma torch according to (3) above, wherein the two-electrode plasma torch (30) is perpendicular to a posture of a surface of the material to be welded. According to this, the two-electrode plasma torch (30) is perpendicular to the welding target material 31a, 31b. The posture of the surface makes it easy to set or adjust the penetration welding condition of the leading pole and the common welding condition of the trailing pole.

(5) The method of welding a two-electrode plasma torch according to any one of (1) to (4) above, wherein the preceding pole is set to a plasma arc that generates a material for preheating the welding target, The rear electrode is set in the plasma arc of the penetration welding. When the row electrode is located before the front end of the material to be welded (including the front end) after the penetration welding, the plasma arc of the penetration welding is started by the rear pole, the foregoing first The plasma arc of the pole is started at the same time as the plasma arc of the penetration weld or before the generation of the plasma arc, and the driving drive is started at the same time as or after the start of the plasma arc (Fig. 7 and Fig. 9, Figure 16).

According to this, although a preheating time lag corresponding to the distance between the leading/rearing poles (residues in FIGS. 19(a) and (b)) is generated, the cold steel plate section without preheating reduces the speed of the traveling drive. Thereby, it is possible to reduce the formation of poor penetration waves at the tip end of the material to be welded. As long as it exceeds the preheating time lag interval, the steel plate is easily welded in the first step by the preheating effect of the leading electrode, and the traveling drive speed is improved, and the productivity of the welding can be improved.

When the leading pole (for preheating) is located at the front end of the material to be welded, the plasma arc (preheating) is started at the leading pole (for preheating), thereby avoiding the pre-equivalent to the distance between the leading/rearing poles The thermal wave lag (Fig. 19(a)) causes poor penetration of the osmotic wave at the tip of the material to be welded (residue of Fig. 19(b)). As long as the penetration is formed by the trailing pole, the steel sheet is easily welded to the rear end by the preheating effect of the leading pole, and the traveling drive speed is improved, whereby the weld productivity can be improved.

The rear end of the material to be welded is subjected to a low-speed, low-current fusion interface treatment (Fig. 7, Fig. 8, Table 1), whereby the high speed and high current are shortened to extend to the rear osmotic wave to form an arc (for example, a penetrating arc). The molten pool pulls the molten liquid flowing back to the rear side to penetrate the welding arc side, thereby correcting the recess of the rear end surface to be flat, and reducing the back end defect. With these procedures, the raw materials of the front end and the rear end of the material to be welded can be improved. Material yield.

(6) The method of welding a two-electrode plasma torch according to any one of the above items (1) to (4), wherein the preceding pole is set in a plasma arc for penetration welding, and the foregoing is performed The pole is set in a plasma arc that welds the weld line together, and is set before the front end of the penetration weld is located before the front end of the material to be welded (including the front end), and the plasma arc that penetrates the fusion is started by the preceding pole, The plasma arc of the rear row is started when the plasma arc of the penetration welding is started or at the front end of the material of the welding target, and the driving drive is started at the same time as or after the plasma arc is started first or simultaneously. (Figure XI, Figure 14).

According to this, the front end of the material to be welded is handed to the rear end, and the smooth plasma arc with less flow of the pilot gas and lower current is used, immediately after the plasma arc of the first penetration welding. In the vicinity, only the surface is arc-melted, whereby the welded surfaces are commonly welded, and even a high-speed welding can obtain a surface seam with less depression. As long as the trailing pole reaches the front end of the welding target material, the plasma arc current of the leading pole is increased, and the traveling driving speed is increased, thereby reducing the residual penetration of the front end portion (Fig. 19(b)). Improve the productivity of welding.

The rear end of the material to be welded is subjected to a low-speed, low-current fusion interface treatment (Fig. 11, Fig. 12, Table 3), thereby shortening the plasma arc after extending to the subsequent penetration welding by high speed and high current. The molten pool pulls the molten liquid flowing back to the back side of the permeation wave arc, thereby correcting the depression of the rear end surface to be flat, and reducing the back end defect. By these procedures, the raw material yield of the front end and the back end of the welding target material can be improved.

(7) The method of welding a two-electrode plasma torch according to the above (5), wherein when the trailing pole is located at a front end of the material to be welded, the plasma arc of the preceding and succeeding poles is simultaneously activated, Simultaneously with the start, the aforementioned travel drive is started at a low speed, as long as the trailing pole reaches the position of the preceding pole to start the plasma arc. The high-speed switching of the traveling drive is performed, and the plasma arc current and the plasma gas flow rate of the row electrode after the switching are increased, and the plasma of the leading electrode is advanced before the leading electrode is about to reach the end of the welding target material. Both or one of the arc current and the plasma gas flow are reduced, as long as the trailing pole reaches the rear end, the speed of the travel drive is reduced, and the plasma arc current and the plasma gas flow of the trailing pole are both The one or the other is lowered, and the plasma arc of the leading and trailing poles is stopped after the processing of the post-melting interface (Fig. 7, Table 1).

According to this, the leading electrode (for preheating) that enters the range of the material to be welded from the tip end of the material to be welded and the row electrode (for penetration welding) after the tip of the material to be welded start the plasma arc at the same time, thereby generating the equivalent of the leading pole. / Preheating time lag of the inter-electrode distance (remaining in Fig. 16(b)), but the traveling speed is low, so that the formation of the osmotic wave at the tip end of the material to be welded is reduced. As long as the preheating time interval is exceeded, the productivity of welding is increased because the traveling speed is increased. The rear end of the material to be welded is processed by a fusion interface of low speed, low current or plasma gas flow, and the depression of the rear end surface is corrected to be flat, and the back end is less defective. By these procedures, the raw material yield of the front end and the back end of the welding target material can be improved.

(8) The welding method using the two-electrode plasma torch according to (5) above, wherein when the preceding pole is located at the front end of the material to be welded, as long as the plasma arc of the preceding pole is activated (preheating), The traveling drive is started at a low speed, and as long as the trailing pole reaches the front end of the material to be welded, the plasma arc of the rear pole is activated, and when the penetration is formed by the rear row, the driving is switched at a high speed, and the driving is improved. After switching, either or both of the plasma arc current and the plasma gas flow (Fig. 9, Fig. 10, Table 2).

According to this, when the leading electrode (for preheating) is located at the front end of the material to be welded, since the leading electrode (for preheating) starts the plasma arc (preheating), it is not equivalent to the distance between the leading/rearing poles. The preheating time lag (Fig. 16(b)) causes the front end of the material to be welded Poor wave formation. As long as a wave of penetration (for example, penetration) is formed by the trailing pole, the traveling drive speed is increased, and thus the weldability is improved.

(9) The method of welding a two-electrode plasma torch according to (6) above, wherein when the preceding pole is located at a front end of the material to be welded, as long as the plasma arc of the preceding pole is activated (penetration welding), At the same time, the walking drive is started at a low speed, and as long as the trailing pole reaches the front end of the welding target, the plasma arc (common welding) of the rear pole is started, and the high-speed switching is performed as long as the trailing pole reaches the front end of the welding target. In the foregoing driving drive, and improving one or both of the plasma arc current and the plasma gas flow rate after the switching, the plasma arc current and the electric current of the leading electrode are before the leading end is about to reach the end of the welding target material. Both or one of the slurry gas flows are lowered, and the aforementioned travel drive is switched at a low speed, and at the rear end, the plasma arcs of the leading and trailing poles are stopped (Fig. 11, Fig. 12, Table 3).

According to this, the front end of the material to be welded is delivered to the rear end, and the welding surface is welded together by the plasma of the trailing electrode, so that even the high-speed welding can obtain the surface seam with less depression, and the productivity of welding improve. As long as the trailing pole reaches the front end of the welding target material, the plasma arc current for switching the leading pole is increased, and at the same time, the traveling driving speed is increased, so that the weld productivity is improved. At the rear end of the welding target material, the recess of the rear end surface is corrected to be flat by the fusion interface processing of the low speed, low current or low plasma gas flow, and the back end defect is reduced. By these procedures, the raw material yield of the front end and the back end of the welding target material can be improved.

(10) The method of welding a two-electrode plasma torch according to any one of the above-mentioned items (1) to (4), wherein the position is immediately below the plasma flame, by a slit or a groove The open water-cooled copper joint constitutes a front end joint (38a, 38b) which is disposed at a front end of the welding target material (31a, 31b) in the welding direction, before the leading and trailing poles are located before the front end of the welding target material (31a, 31b) When the front end is included, the plasma arc is started at both poles (Fig. 13, Fig. 14, Fig. 16).

According to this, the plasma arc is started and stopped at the front end and the rear end of the welding target material, so that no welding failure occurs at the front end and the rear end. The raw material yield of the front end and the rear end of the welding target material is improved. According to the thickness or material of the plate, at the front end and the rear end, the current flowing through the welding side or the flow rate of the plasma gas and the welding speed are reduced, and the welding of the front end portion or the welding of the rear end portion is performed.

(11) The welding method using the two-electrode plasma torch according to (4), wherein the traveling drive is started as long as the two electrodes simultaneously start the plasma arc (Fig. 14 and Fig. 16).

(12) The method of welding a two-electrode plasma torch according to the above (10), wherein the preceding pole is set in a plasma arc that penetrates the fusion, and the rear row is set to electrically weld the weld line together. The plasma arc is set before the front end of the penetration welding is located at the front end of the material to be welded (including the front end), and the plasma arc of the penetration welding is started by the preceding pole, and the plasma arc of the rear row is started to be worn. The pulverized plasma arc is simultaneously activated at the same time as the front end of the welding target material, and the preceding driving is started at the same time as or after the start of the plasma arc (Fig. 14, Fig. 15, Table) 4).

(13) The method of welding a two-electrode plasma torch according to the above (10), wherein the preceding pole is set to a plasma arc that generates a material for preheating welding, and the rear row is set to penetrate welding The plasma arc is set when the row electrode is located before the front end of the material to be welded (including the front end) after the penetration welding, and the plasma arc of the penetration welding is started by the rear pole, and the plasma arc of the preceding pole is Simultaneously with or before the plasma arc that penetrates the fusion, the aforementioned travel drive is started at the same time as or after the start of the plasma arc (Fig. 16, Fig. 17).

(14) A fusion joint using a two-electrode plasma torch (30) according to the above (1) a method in which, in the relative movement of the two-electrode plasma torch (30) and the welding target material (W) in the welding, the front end surface of the front end joint (113) is opposite to the beginning end of the welding target material (W), and the front end joint (113) opposite to the front end of the two-electrode plasma torch (30), from a standby position where the welding arc is activated (Fig. 23), in the relative moving direction (y), the front end surface is from the two electrodes The plasma torch (30) and the material to be fused (W) are separated from the retracted position (Fig. 28), and conversely, the joint (113) is movably supported by the front end joint driving means (105) And 111) placing the front end joint (113) at the standby position (Fig. 23), and the front end of the relative moving direction (y) of the welding target material (W) abuts against the front end joint (113) At the front end face, or immediately before or immediately after the abutment, the leading electrode (20b) in the direction in which the weld line extends, and the row electrode (20a) after the subsequent row start the plasma arc (Fig. 23) To Figure 28).

According to this, a plasma arc is generated between the two-electrode plasma torch (30) and the front end joint (113), and the stability of the starting arc is high. After the arc is started, the front end joint (113) is pushed toward the retracting direction by welding the material of the object, or the front end joint (113) is driven to the retracting direction by the front joint driving means (113, 111) as long as the front end joint (113) The front end face is separated from the two-electrode plasma torch (30), and the front end joint (113) can be driven to the retracted position by the front end joint driving means (105, 111). After driving to the retracted position, as long as the welding target material (W) passes through the front end joint (113) after the welding is completed, the front end joint driving means (105, 111) is used to return the front end joint (113) to the standby position, waiting When the next welding target material comes, the welding of the welding target material can be performed in the same manner. The movement between the standby position/retraction position of the front end connector (113) is automatically performed by the front end joint driving means (105, 111), so that the welding arc can be stably started, and the continuous production of a plurality of short strip products can be efficiently performed. .

(15) The welding method using the two-electrode plasma torch (30) according to (14) above, wherein the front end joint driving means (105, 111) comprises: a first driving device (111), from the standby position (Fig. 23), in the direction of the relative movement (y), the front end of the front end joint is separated from the set position of the two-electrode plasma torch (30) (Fig. 27) And conversely, movably supporting and driving the front end joint (113); and the second driving device (105), wherein the front end joint (113) drives the first driving device (111) from the standby position Driving in the aforementioned set position (Fig. 27), or conversely driving from the driven position (Fig. 23 to Fig. 27), driving the front end joint (113) to become the non-action of the retracted position The position (Fig. 28), or conversely, is movably supported and driven (Fig. 23 to Fig. 28).

(16) The welding method using the two-electrode plasma torch (30) according to (15) above, wherein the first driving device (111) and the second driving device (105) respectively comprise cylinders (Fig. 23 to Figure 28).

(17) The welding method using the two-electrode plasma torch (30) according to (14) above, wherein the front end joint (113) is covered with a high magnetic permeability cover (114) against a high thermal conductivity substrate At least the lower end of the front end portion (113p) of the start of the welding target material (W).

According to this, even when the welding arc (PA-T) is located at the welding start end portion (TP-A) of the welding target material (W), as shown in Fig. 29, the magnetic flux induced by the arc moves to the front side. Since the magnetic permeability cover (114) spreads forward, the force against the material of the welding target (the direction of the y arrow) acting on the welding arc (PA-T) is small, and the welding arc (PA-T) The transverse direction becomes smaller, and the welded seam at the beginning of the welding becomes flat.

(18) The welding method using the two-electrode plasma torch (30) according to (17) above, wherein the aforementioned two-electrode plasma torch is equipped with the aforementioned front end joint device (Fig. 23 to Fig. 28) .

(19) The welding method using the two-electrode plasma torch (30) according to the above (14), wherein the front end joint (113p) is placed in the standby position at the beginning of the transfer of the welding target material (W) Abutting the front end of the front end connector (113p) or Before it is abutted or immediately after the abutment, a plasma arc that penetrates the fusion is started between the aforementioned light-emitting pole and the front end joint (113p), and in the foregoing rear row pole and the front end joint (113p) a plasma arc of the common welding is started, and the beginning end of the welding target material (W) passes through the two nozzles immediately below, and the front end surface of the front end joint (113p) does not interfere with the position of the plasma torch (30). The front end joint (113p) is driven to the retracted position, and as long as the end of the welding target material (W) is separated from the plasma arc, the plasma arc is stopped, and thereafter, the welding target material (W) is moved to not interfere with the front end joint. After moving to the position where the standby position is moved, the front end joint (113p) is placed in the standby position (Fig. 25).

According to this, the plasma arc (PA-L, PA-T) of the penetration welding and the common welding is stably started, and the continuous production of a plurality of short strip products can be performed with high efficiency. In particular, when the above-mentioned (17) front end fitting device is used, when the trailing plasma arc (PA-T) is located at the welding start end portion (TP-A) of the welding target material (W), as shown in FIG. As shown, the magnetic flux induced by the arc is moved to the front cover of the high magnetic permeability (114) and spreads forward, so that the material of the welding target material is applied to the rear plasma arc (PA-T) (y arrow) The direction of the reverse direction becomes smaller, the transverse deflection of the trailing plasma arc (PA-T) becomes smaller, and the welded joint at the beginning of the fusion becomes flat.

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

(Example)

Fig. 1(a) is a view showing an example of a system of a welding device for performing the welding method of the two-electrode plasma torch of the present invention. In the present embodiment, in the horizontal direction x perpendicular to the plane of the paper, the opposite end faces are butted to form a welded wire. The welding target materials 31a and 31b are fixed, and the two-electrode plasma torch 30 is supported by a traveling mechanism (not shown), and the torch running motor 36 is opposed to the welding wire from the beginning of the left side of the welding wire (welding) The front end of the target material is driven to the right side of the left end to the right end (the rear end of the welding target material) in the direction y parallel to the weld line. In addition, in the embodiment of the present invention, there is also a state in which instead of the travel-driven two-electrode plasma torch 30, as shown in FIG. 1(b), the two-electrode plasma torch 30 is fixedly disposed, and the welding is supported by the traveling platform. The target materials 31a and 31b pass through the traveling mechanism, and the workpiece traveling motor has a position from the front end of the welding target material to the right side of the two-electrode plasma torch 30 to the left end of the welding target material material to the left side of the two-electrode plasma torch 30. The traveling platform is driven to drive in a direction y parallel to the weld line. However, for the sake of simplicity, the following describes the state of the two-electrode plasma torch 30 which is the former of the travel drive.

Referring again to FIG. 1(a), the parallel operation control panel 35 for performing the fusion control is a computer control circuit, and the main components thereof include a CPU and a built-in memory program (microcomputer), a display, and an operation panel (touch panel, etc.). The operator performs a stylized two-electrode plasma arc welding control program. The two-electrode plasma torch 30 is provided with two sets of plasma arc generating mechanisms, and the welding power-gas supply devices 32a and 32b perform the plasma arc starting and stopping of one group and the other group.

The parallel operation control panel 35 supplies the respective plasma arc currents, the plasma gas flow rates, and the start and stop commands to the welding power-gas supply devices 32a and 32b, respectively, and the welding power-gas supply devices 32a and 32b activate the respective commands in accordance with the respective commands. The plasma arc is switched to switch the plasma arc current-switching the gas flow rate and stopping, and further, the status information of each group is supplied to the parallel operation control panel 35. The parallel operation control panel 35 also issues a command for starting (walking), stopping, and speed to a motor driver (motor controller: abbreviated) that performs driving, stopping, and speed control of the torch motor 36, and the motor driver follows the command. The start, stop, and speed change of the motor 36 are performed, and the travel drive position of the two-electrode plasma torch 30 (the position of the welding target y to the material to be welded) is measured, and the positional data is supplied to the parallel operation control panel 35. The operation control panel 35 refers to the location data to switch the contents of the program control (Fig. 8, Table 1).

Figure 2 is an enlarged longitudinal cross-sectional view showing a portion of the two-electrode plasma torch 30 shown in Figure 1. The pointed base of the embedded pointed tip 1 is embedded with a screw, and the inner cover 6 is screwed to the pointed end 5, thereby being fixed to the pointed end 5. The pointed end 5 is fixed to the insulative housing 7, and the electrode holders 10a and 10b and the insulating spacer 11 are fixed to the insulative housing 7.

The shield case 8 is fixed to the insulative housing 7. The first electrode stage 10a and the second electrode stage 10b which are separated in the diameter direction of the outer cylinder 14 by the second distribution are separated by the insulating spacer 11.

In the illustrated embedded tip, two nozzle members 20a and 20b are attached to the tip base of the embedded tip 1. Referring to FIG. 5 in detail, in each of the nozzle members 20a and 20b, a nozzle 3a is provided in the center thereof. 3b open umbrella portions 21a, 21b; trunk portions 22a, 22b connected to the umbrella portion; and male screw portions 24a, 24b connected to the trunk portion; and an O-ring 23a which is a sealing material between the trunk portion and the male screw portion, 23b has internal electrode arrangement spaces 2a and 2b that communicate with the nozzles 3a and 3b.

The tip base of the recessed tip 1 includes cooling water circulation holes 1f and 1g which are inserted into the nozzle member insertion holes 18a and 18b and the nozzle members which are inserted from the male screw portion of each nozzle member to the stem portion. The umbrella portion of each nozzle member of the insertion hole abuts against the front end planes 1d, 1e, thereby forming a portion of the nozzle member insertion hole that is closed, and a cooling water passage space is formed between the stem portion and the stem portion; the water receiving hole 1h (Fig. 4) a water outlet hole 1i; a lateral water passage hole 1j adjacent to the cooling water circulation hole; a lateral water passage hole 1k connecting the cooling water circulation hole 1f to the water receiving hole 1h; and a lateral water passage connecting the cooling water circulation hole 1g to the water outlet hole 1i Hole 1l.

As shown in FIG. 5(a), the nuts 25a, 25b are screwed to the male screw portions 24a, 24b of the nozzle members 20a, 20b, and are locked to the tip base of the embedded tip 1, thereby the nozzle member 20a, 20b are bonded to the pointed base of the embedded tip 1.

Referring again to FIG. 2, the electrode arrangement spaces 2a, 2b of the nozzle members 20a, 20b are distributed at the same diameter perpendicular to the central axis (z) of the tip base of the embedded tip 1. A line (y) extending parallel to the central axis (z) from the central axis at equal distances. In the present embodiment, the nozzles 3a and 3b connected to the electrode arrangement spaces 2a and 2b are concentric with the central axes of the electrode arrangement spaces 2a and 2b, and are opposed to the welding target materials 31a and 31b. In the present embodiment, the nozzles 3a, 3b are also distributed on the same diameter line (y) perpendicular to the central axis (z) of the pointed base body (outer cylinder 14) of the embedded tip 1, parallel to the central axis. And at an equal distance.

The first electrode 12a and the second electrode 12b, which are inserted into the electrode arrangement spaces 2a and 2b, penetrate the insulating body 7, and are fixed to the electrode pads 10a and 10b by the pressing screws 13a and 13b, and the positioning stones 9a and 9b are used. Positioned at the axial center of each electrode arrangement space 2a, 2b. The nozzles 3a and 3b connected to the respective electrode arrangement spaces 2a and 2b are opened to the front end surface (lower end surface) facing the welding target materials 31a and 31b of the tip base of the embedded tip 1. The direction in which the straight line (y) connecting the nozzles 3a, 3b extends is the welding direction. The pointed base of the embedded tip 1 is broad in the direction in which the straight line (y) extends (welding direction) as shown in FIG. 2, but the direction perpendicular to the straight line (y) (x) is the groove of the welded object. The width direction is wedge-shaped, and the side faces become inclined faces 1a and 1b (Fig. 4(a)).

Referring to FIG. 4(a), the front end surface of the flare (the lower end surface of the nozzle in FIG. 2) is shown. The front end projection 1c is located at the center axis of the tip end of the tip end of the embedded tip 1, and is in the y direction which becomes the welding direction. On both sides of the front end projection 1c, there are front end planes 1d, 1e for receiving the back surfaces of the umbrella portions 21a, 21b of the nozzle members 20a, 20b. At the center of each of the front end planes 1d and 1e, there are nozzle member insertion holes 18a and 18b (Fig. 5(b)). One of the arcs of the umbrella portions 21a and 21b of the nozzle members 20a and 20b inserted into the nozzle member insertion holes 18a and 20b is deleted into a linear slit surface 26a, 26b which is in close contact with the side surface of the front end projection 1c, that is, the locking surface. . That is, the engagement is performed. Thereby, the rotation of the nozzle members 20a, 20b about the central axis of the pointed base of the embedded tip 1 is prevented. In this engagement, the nozzle members 20a and 20b are inserted into the tip base of the insertion tip 1, and when the nuts are screwed and fixed by the nuts 25a and 25b, the nozzle member 20a is prevented. The 20b rotation function and the function of preventing the nozzle members 20a and 20b from rotating when the nozzle members 20a and 20b are gradually removed from the tip base of the embedded tip 1 are slowly rotated. This engagement further has the function of fixing (setting) the inclination direction of the nozzle axis of the nozzle member 20c, 20d (FIG. 6) in which the nozzle axis is inclined to the center axis (z) of the tip base in the welding direction (y). .

The portions of the nozzle member insertion holes 18a and 18b on the front end planes 1d and 1e are large-diameter cooling water circulation holes 1f and 1g, and cooling is formed between the cooling water circulation holes 1f and 1g and the outer peripheral surfaces of the dry portions 22a and 22b penetrating therethrough. Water circulation space (refrigerant circulation space).

Figure 4(c) shows the cross section of the pointed base of the embedded tip 1 (section IVc-IVc on Figure 2). The tip base of the embedded tip 1 has a water receiving hole 1h, a water outlet hole 1i, a lateral water passing hole 1j connecting the cooling water circulation holes 1f and 1g, and a lateral water passing the cooling water circulation hole 1f to the water receiving hole 1h. The hole 1k and the cooling water circulation hole 1g are connected to the lateral water hole 11 of the water outlet hole 1i.

Figure 3 shows a section perpendicular to the section of Figure 2. The water receiving hole 1h of the tip base of the embedded tip 1 is connected to the water flow pipe 16a, and the water outlet hole 1i is connected to the water flow pipe 16b. Referring to FIG. 4(c), the cooling water injected into the water flow pipe 16a passes through the water flow path of the electrode stage 10a, the insulating body 7, and the tip stage 5, and flows into the water receiving hole 1h of the tip base of the embedded tip 1. It flows to the bottom of the hole, from which it flows into the cooling water circulation space between the water circulation hole 1f and the outer peripheral surface of the trunk portion 22a through the lateral water passage hole 1k, and then flows into the outer circumference of the water circulation hole 1g and the trunk portion 22b through the lateral water passage hole 1j. The cooling water circulation space between the two passes through the lateral water passage 11 and then flows into the water flow pipe 16b, and then flows out from the outside of the flare.

The cooling water flows between the water circulation hole 1f and the peripheral surface of the trunk portion 22a and the cooling water circulation space between the water circulation hole 1g and the outer surface of the trunk portion 22b, and the trunk portions 22a, 22b of the nozzle members 20a, 20b are effectively cooled. And cooling The water is in between the water receiving hole 1h, the lateral water passing hole 1k, the water circulation hole 1f, the lateral water passing hole 1j, the water circulation hole 1g, the lateral water passing hole 11l, and the water outlet hole 1i, and the tip base of the embedded tip 1 is Effective cooling, so the embedded tip has a higher cooling capacity. At the time of welding, the nozzle members 20a, 20b are also heated as quickly as possible, but the outer peripheral surface thereof is cooled by direct contact with the cooling water, so that the nozzle members 20a, 20b have a long service life.

Referring again to Fig. 2, the igniting gas system enters the electrode arrangement spaces 2a, 2b through the igniting gas tubes 15a, 15b and the electrode insertion space, and a plasma arc is formed at the tip end portion of the electrode, and is ejected from the front end face of the torch through the nozzles 3a, 3b. The shield gas passes through the shield gas pipe (not shown), enters the cylindrical space between the inner cover 7 and the shield case 8, and is ejected from the tip end of the torch to the welding target materials 31a and 31b.

As shown in Fig. 2, between the electrodes 12a and 12b and the nozzle members 20a and 20b, between the ignition power sources 34a and 34b that generate the ignition arc, and the electrodes 12a and 12b and the welding target materials 31a and 31b, there is an electrode side flow. The negative plasma arc current, the plasma arc power source 33a, 33b of the positive plasma arc current flowing on the side of the welding target material. The igniting power sources 34a, 34b and the plasma arc power sources 33a, 33b are located in the splicing power-gas supply devices 32a, 32b, and the plasma arc power sources 33a, 33b are capable of setting preheating, penetration welding (formal welding) and welding of common welding. The condition is such that either one of the two electrodes 12a and 12b is used as the preceding row in the welding direction, or one of the leading and trailing rows is set to penetrate the fusion, and when the other electrode is the leading electrode, the preheating is performed. When the rear row is poled, it is set to the common welding, and each plasma arc current can be set. Fig. 2 shows that the leading electrode 12b is set to preheat, and the succeeding electrode 12a is set to the fusion welding state of the penetration welding. The plasma arcs 19a and 19b are mutually restrained by magnetic interference with each other, and the arc is a slightly curved arc as shown in the figure.

A pyrophoric arc is generated between each of the electrodes 12a and 12b and the tip 1 by the ignition power sources 34a and 34b, and a negative plasma arc current flows between the electrodes 12a and 12b and the welding target materials 31a and 31b. , the parent material side flow positive plasma arc current The plasma arc power source 33a, 33b generates a welding arc (plasma arc) by a plasma arc power source 33b that supplies power to the light electrode 12b in the welding direction and a plasma arc power source 33a that supplies power to the trailing electrode 12a in the welding direction. The plasma arc current flows between the electrodes 12a, 12b and the welding target materials 31a, 31b, so that a single molten pool double arc welding can be realized. Fig. 2 shows a state in which the electrode 12b is preheated by the preceding electrode, and the electrode 12a is subjected to the common welding (formal welding). However, the electrode 12b can be used for the penetration welding, and the electrode 12a is used. Perform the common welding (flattening). That is, the plasma arc of the common welding of the trailing electrode 12a contacts the molten pool formed by the penetration welding of the leading electrode 12b, for example, the subsequent common welding enables the surface seam of the high-speed penetration welding to occur. The deeper depression is flat. Thereby, a welded seam having less depression can be obtained even at a high speed.

Fig. 6 (b1) is a longitudinal section of the nozzle member 20c according to the first modification used in place of the nozzle member 20a and/or 20b shown in Fig. 2, and Fig. 6(b2) shows the bottom surface (front end surface of the nozzle member 20c). ). The central axes of the nozzles 3a, 3b of the nozzle members 20a, 20b shown in Fig. 2 are concentric with the central axis of the nozzle member. However, the nozzle 3c of the nozzle member 20c is inclined to the central axis of the nozzle member 20c. Therefore, as long as the nozzle member 20c is attached to the tip base of the insert tip 1, the slit surface 26c is engaged with the recessed tip. In the state of the tip end projection 1c of the tip base of the head 1, the center axis of the nozzle 3c is inclined in a direction away from the central axis of the tip base of the insertion tip 1 (the intermediate point of the nozzle member insertion hole). That is, the central axis of the pointed base of the embedded tip 1 is inclined to the front side (when the nozzle is advanced) or the rear side (becoming the trailing nozzle) in the welding direction (y), and the pole can be enlarged ( Welding of the distance between the front and rear welding points).

Fig. 6 (c1) is a longitudinal cross-sectional view of the nozzle member 20d according to the second modification used in place of the nozzle members 20a and 20b shown in Fig. 2, and Fig. 6(c2) is a bottom surface (front end surface) of the nozzle member 20d. . The nozzle 3d of the nozzle member 20d is inclined to the central axis of the nozzle member 20d in the opposite direction to the nozzle 3c, so that the nozzle member 20d is provided The tip base of the embedded tip 1 is tilted to the tip of the tip of the nozzle 3d in a state where the slit face 26d is engaged with the tip end projection 1c of the tip end of the embedded tip 1. The direction of the central axis of the tip base of the head 1 (the intermediate point of the nozzle member insertion hole). That is, in the welding direction (y), it is inclined so as to be close to the central axis of the tip base of the embedded tip 1, and the plasma arc of the trailing pole becomes the advancing angle with respect to the welding traveling direction, and the welding becomes a more stable state.

In addition, as the embedded tip for attaching the nozzle member to the tip base of the embedded tip 1, there are: (1) the state shown in FIG. 2 and FIG. 5; (2) the nozzle member shown in FIG. 20a is replaced with the nozzle member 20c, the nozzle member 20c is in the welding direction (y) as the preceding nozzle; (3) the nozzle member 20b shown in Fig. 2 is replaced with the nozzle member 20c, and the nozzle member 20c is used as the trailing nozzle (4) The nozzle members 20a, 20b shown in Fig. 2 are collectively used as the nozzle member 20c; (5) the nozzle member 20a shown in Fig. 2 is replaced with the nozzle member 20d, and the nozzle member 20d is used. (6) replacing the nozzle member 20b shown in FIG. 2 with the nozzle member 20d and the nozzle member 20d as the trailing nozzle; (7) the nozzle member 20a shown in FIG. 20b collectively as a form of the nozzle member 20d; (8) replacing the nozzle members 20a, 20b shown in Fig. 2 with the nozzle members 20c, 20d, the nozzle member 20c as a preceding nozzle; and (9) The nozzle members 20a and 20b shown in FIG. 2 are replaced with the nozzle members 20c and 20d, and the nozzle member 20d is first. The state of the nozzle.

Corresponding to the thickness of the welding target and the required welding current, welding speed, and fusion The quality (for example, the shape of the seam to be seamed) can be selected from any of the above (1) to (9) patterns. 20 to 22 show the replacement of the nozzle member 20a shown in FIG. 2 with the nozzle member 20d shown in FIGS. 6(c1) and (c2), and the nozzle member 20b shown in FIG. 2 is replaced. It is the state of the nozzle member 20c shown in Fig. 6 (b1) and (b2). In addition, any of the following embodiments is the same as that shown in FIG. 20 to FIG. 22, and the nozzle member 20a shown in FIG. 2 is replaced with the nozzle shown in FIG. 6 (c1) and (c2). In the member 20d, the nozzle member 20b shown in Fig. 2 is replaced with the nozzle member 20c shown in Figs. 6(b1) and (b2), and the forward angle nozzle is used. The following is an example of a method of welding a two-electrode plasma torch of the present invention.

(First embodiment) 1. After-pass mode (first-pass and back-stage simultaneous ignition) (Figure 7, Figure 8, Table 1)

In the first embodiment, a two-electrode plasma torch 30 is provided, which is provided with an embedded tip 1 having two electrode arrangement spaces 2a, 2b and two nozzles 3a respectively communicating with each electrode arrangement space. 3b; the rear end joints 39a, 39b are disposed at the rear ends of the welding target materials 31a, 31b, and the arrangement direction of the two nozzles is parallel to the weld line, and the two-electrode plasma torch 30 is welded to the welding target material 31a, 31b. While running in the direction along the weld line, a plasma arc is generated by the electrodes 12a and 12b located in the respective electrode arrangement spaces, and the weld line is welded.

In this embodiment and all of the embodiments described later, the rear end joints 39a, 39b are water-cooled copper joints which are slit at positions immediately below the plasma flame, and the front end joints 38a, 38b which are described later are also the same water-cooled copper joints. However, there is also a pattern that replaces the slits where the grooves are formed.

In the first embodiment, the leading electrode is set in the preheating plasma arc, and the rear row electrode is set in the penetrating plasma arc, as shown in Fig. 7 (1), when the rear row electrode (nozzle member 20a) is located in the welding target material. At the beginning of 31a, 31b, the leading pole is simultaneously activated (nozzle member 20b) And the plasma arc of the rear row, and at the same time as the start, the driving of the two-electrode plasma torch 30 is started at a low speed.

As shown in Fig. 7 (2), as long as the trailing pole and the leading pole reach the position where the plasma arc is started, the traveling drive of the two-electrode plasma torch 30 is switched at a high speed, and the plasma arc current of the row electrode after switching is improved and A very high plasma gas flow rate. Thereafter, as shown in Fig. 7 (3), the same conditions are continued. Next, as shown in Fig. 7 (4), before the leading end is about to reach the rear end of the welding target materials 31a, 31b, the plasma arc current of the leading electrode is lowered, at the rear end of the welding target materials 31a, 31b, as shown in Fig. 7 (5). As shown, as long as the trailing pole reaches the rear end, the speed of the aforementioned travel drive is reduced, and the plasma arc current of the rear row pole is lowered, and the front pole and the back row are stopped after the processing of the melt interface of the rear row pole. Extreme plasma arc plasma. Thereafter, the driving of the torch is stopped (Fig. 7 (6)).

Fig. 8 is a basic diagram showing the welding current, the plasma gas flow rate, and the welding speed at the time points T1 to T4 at which the switching poles reach the respective positions shown in Figs. 7(3) to (6), and Table 1 shows the first embodiment. The welding condition value used. In this way, the welding target materials 31a and 31b are made of mild steel having a thickness of 3.6 mm (thick plate) and a length of 200 mm, and in the welding program, from the start of welding (STEP 1) to the end of welding (STEP 12), for each step of the 12 steps. Set the welding condition value. Between the steps, the welding condition value of the preceding step is maintained. Further, the nozzle inclination angle of 20° is an angle of inclination in which the nozzle is inclined by 20° in the direction before the welding direction y, and the nozzle member 20b which has entered the leading pole 12b shown in Fig. 2 is replaced with Fig. 6 (b1) and (b2). The nozzle member 20c shown in Fig. 2 replaces the nozzle member 20a of the electrode 12a shown in Fig. 2 with the nozzle member 20d shown in Figs. 6(c1) and (c2), thereby achieving a nozzle tilt angle of 20°.

(Table 1)

According to the first embodiment, the pre-heating forward electrode for entering the welding target material range from the front end of the welding target material, that is, the welding target material 31a, 31b, and the plasma electrode at the front end of the welding target material are simultaneously activated. The arc, thus producing a preheating time lag corresponding to the distance between the leading/rearing poles (Fig. 16(b)), but due to the driving drive Since the moving speed is low, the penetration wave at the front end of the material to be welded is less formed. As long as the preheating time lag interval is exceeded, the traveling drive speed is increased, so that the productivity of welding is high. The rear end of the welding target materials 31a, 31b is processed by a low-speed, low-current fusion interface to correct the depression of the rear end surface to be flat, and the rear end electrode is welded at the rear end of the welding target material until the plasma arc is stopped. The plasma arc is continued first, so that the welding of the material of the welding target is completed, and the plasma flame of the rear pole and the plasma flame of the leading pole are mutually restrained, and the plasma flame is not generated after the rear end does not generate the plasma flame of the rear pole. Therefore, at the rear end, the surface seam is not formed elongated at the rear, and the recess at the rear end portion disappears. By these procedures, the raw material yields of the front end and the rear end of the welding target materials 31a and 31b are improved.

(Second embodiment) 2. After-pass mode (first-pass first-hand ignition) (Figure 9, Figure 10, Table 2)

The second embodiment also uses a two-electrode plasma torch 30 which is provided with a built-in tip 1 having two electrode arrangement spaces 2a, 2b and two nozzles 3a respectively communicating with each electrode arrangement space. 3b; the rear end joints 39a, 39b are disposed at the rear ends of the welding target materials 31a, 31b, and the arrangement direction of the two nozzles is parallel to the weld line, and the two-electrode plasma torch 30 is welded to the welding target material 31a, 31b. While running in the direction along the weld line, a plasma arc is generated by the electrodes 12a and 12b located in the respective electrode arrangement spaces, and the weld line is welded.

The leading pole is set in the preheating plasma arc, the trailing pole is set in the penetrating plasma arc, and the driving of the two-electrode plasma torch 30 is started at a low speed, as shown in FIG. 9(1), when the leading pole (nozzle member 20b) When the front end of the welding target material 31a, 31b is located, the plasma arc of the leading electrode is activated. As shown in Fig. 9 (2), as long as the trailing pole reaches the beginning of the welding target materials 31a, 31b, the plasma arc of the rear row is activated, and when the penetration is formed by the trailing pole, the traveling drive is switched at a high speed. Moreover, the plasma arc current of the row pole after switching and the plasma gas flow rate of the trailing pole are increased. Thereafter, as shown in Figure IX (3), continue the phase Same conditions. Next, as shown in Fig. 9 (4), as long as the trailing pole reaches the rear end of the welding target materials 31a, 31b, the plasma arc of the leading and trailing poles is stopped. Then, stop the torch drive (Figure 9 (5)).

Fig. 10 shows the basic pattern of the welding current, the plasma gas flow rate, and the welding speed at the time T1 to T3 at which the switching poles reach the respective positions shown in Figs. 7(3) to (5), and Table 2 shows the second embodiment. The welding condition value used in the example. In this way, the welding target materials 31a and 31b are made of a soft steel having a thickness of 2.3 mm (thin plate) and a length of 220 mm. In the welding program, from the start of welding (STEP1) to the end of welding (STEP 13), the welding is set for each step of the 13 steps. Conditional value. Between the steps, the welding conditions of the preceding steps are maintained.

(Table 2)

According to the second embodiment, when the leading electrode (preheating) is located at the front end of the welding target materials 31a, 31b, the leading electrode (for preheating) starts the plasma arc (preheating), so that it is not equivalent to the leading pole / The preheating time lag of the inter-electrode distance (Fig. 16(b)) causes poor penetration of the permeable wave at the tip end of the welding target materials 31a and 31b. Just by the formation of the posterior pole Penetration increases the driving speed of the travel, so the productivity of welding is improved. The rear pole ends the welding at the rear end of the welding target material until the plasma arc is stopped, and the plasma arc is advanced, so that the welding of the welding target material is completed, and the plasma flame of the rear pole and the plasma flame of the leading pole are mutually The pinning is not biased after the back end does not generate the plasma flame of the trailing pole, so at the rear end, the surface seam is not formed elongated at the rear, and the recess at the rear end portion disappears. By these procedures, the raw material yields of the front end and the rear end of the welding target materials 31a and 31b are improved.

(Third embodiment) 3. Advance Penetration Mode (first step first ignition) (Figure XI, Figure 12)

The third embodiment also uses a two-electrode plasma torch 30, which is provided with a built-in tip 1 having two electrode arrangement spaces 2a, 2b and two nozzles 3a respectively communicating with each electrode arrangement space. 3b; the rear end joints 39a, 39b are disposed at the rear ends of the welding target materials 31a, 31b, and the arrangement direction of the two nozzles is parallel to the weld line, and the two-electrode plasma torch 30 is welded to the welding target material 31a, 31b. While running in the direction along the weld line, a plasma arc is generated by the electrodes 12a and 12b located in the respective electrode arrangement spaces, and the weld line is welded.

The leading pole is set to penetrate the plasma arc, the rear pole is set to the common welding plasma arc, and the torch driving is started at a low speed, as shown in FIG. 11(1), when the leading pole (nozzle member 20b) is located at the welding target At the beginning of the materials 31a, 31b, the plasma arc (penetration) of the leading electrode is activated. As shown in Fig. 11 (2), as long as the trailing pole reaches the beginning of the welded pin-like materials 31a, 31b, the plasma arc (common welding) of the rear row is activated to switch the driving at a high speed. And to increase the plasma arc current of the leading pole and the plasma gas flow of the light row. Thereafter, as shown in Fig. 11 (3), the same conditions are continued. Next, as shown in FIG. 11 (4), before the leading end is about to reach the rear end of the welding target materials 31a, 31b, the plasma arc current and the plasma gas flow rate of the leading electrode are lowered, and the traveling drive is switched at a low speed, as shown in FIG. As shown in (5), as long as the back line reaches the back end, then The plasma arc current of the trailing pole is reduced, and the plasma arc of the leading and trailing poles is stopped after the processing of the welding interface of the trailing pole. Then, stop the torch drive (Figure 11 (6)).

Figure 12 shows the basic pattern of the welding current, the plasma gas flow rate, and the welding speed at the time T1 to T3 at which the switching poles reach the respective positions shown in Figs. 11(3) to (6). Table 3 shows the 3 The welding condition values used in the examples. In this case, the welding target materials 31a and 31b are made of a soft steel having a thickness of 5.0 mm (thick plate) and a length of 300 mm. In the welding program, from the start of welding (STEP1) to the end of welding (STEP 15), the steps for the steps of 15 are set. Welding condition value. Between the steps, the welding conditions of the preceding steps are maintained.

(table 3)

According to the third embodiment, the front end of the welding target material 31a, 31b is handed to the rear end, and the welding surface is welded together by the plasma of the rear end electrode, even if the high speed welding is also performed. Surface seams with less depressions can be obtained. The productivity of welding is improved. As long as the trailing pole reaches the front end of the welding target materials 31a, 31b, the plasma arc current for switching the leading pole is increased, and the traveling driving speed is increased, so that the productivity of the welding is high. The rear pole ends the welding at the rear end of the welding target material until the plasma arc is stopped, and the plasma arc is advanced, so that the welding of the welding target material is completed, and the plasma flame of the rear pole and the plasma flame of the leading pole are mutually The pinning is not biased after the back end does not generate the plasma flame of the trailing pole, so at the rear end, the surface seam is not formed elongated at the rear, and the recess at the rear end portion disappears. By these procedures, the raw material yields of the front end and the rear end of the welding target materials 31a and 31b are improved.

(Fourth embodiment) 4. First penetration mode (using joint material: first pole, rear pole simultaneous ignition)

The fourth embodiment also uses a two-electrode plasma torch 30 which is provided with an embedded tip 1 having two electrode arrangement spaces 2a, 2b and two nozzles 3a respectively communicating with each electrode arrangement space. 3b; as shown in FIG. 13, the front end joints 38a, 38b and the rear end joints 39a, 39b are disposed at the front end and the rear end of the welding target materials 31a, 31b, so that the arrangement direction of the two nozzles is parallel to the weld line. The two-electrode plasma torch 30 is driven while the welding target materials 31a and 31b are driven in the direction along the weld line, and a plasma arc is generated by the electrodes 12a and 12b located in the respective electrode arrangement spaces, and the weld line is applied. Welding.

The leading pole is set to penetrate the plasma arc, and the trailing pole is set to the common welding plasma arc, as shown in FIG. 14(1), when the leading electrode (nozzle member 20b) is located at the beginning of the welding target materials 31a, 31b, Start the plasma arc (penetration welding) of the leading pole and the plasma arc (common welding) of the rear pole, and start the driving of the torch at high speed, as shown in Figure 14 (2), as long as the rear pole reaches the welding At the beginning of the object materials 31a, 31b, The traveling drive is switched at a high speed, and the plasma arc current of the switching light source and the plasma gas flow rate of the leading electrode are increased, and thereafter, the same conditions are continued as shown in Fig. 14 (3). Next, as shown in Fig. 14 (4), as long as the trailing pole reaches the rear end of the welding target materials 31a, 31b, the plasma arc of the leading and trailing poles is stopped. Then, stop the torch drive (Figure 14 (5)).

Figure 15 shows the basic pattern of the welding current, the plasma gas flow rate, and the welding speed at the time T1 to T3 at which the switching poles reach the respective positions shown in Figs. 14(3) to (5). Table 4 shows the 4 The welding condition values used in the examples. In this way, the welding target materials 31a and 31b are made of a soft steel having a thickness of 1.4 mm (thin plate) and a length of 300 mm. In the welding program, from the start of welding (STEP1) to the end of welding (STEP 11), the welding is set for each step of the 11 steps. Conditional value. Between the steps, the welding conditions of the preceding steps are maintained.

(Table 4)

According to the fourth embodiment, the front end of the welding target material 31a, 31b is delivered to the rear end, and the welding surface is welded together by the plasma of the trailing electrode, so that even the high-speed welding can obtain a surface seam with less depression. The productivity of welding is improved. As long as you go to the end When the front ends of the welding target materials 31a and 31b are increased, the plasma arc current of the preceding poles is increased, and the traveling driving speed is increased, so that the productivity of the welding is improved. The front end joints 38a and 38b and the rear end joints 39a and 39b are disposed at the front end and the rear end of the material to be welded, and the leading end is continued from the front end of the welding target material to the rear end of the welding target material. And the plasma arc of the rear row, at the end of the welding of the material to be welded, the plasma flame of the rear pole and the plasma flame of the leading pole are mutually restrained, and the front end and the rear end of the welding target material are not generated. The plasma flame of the row is deflected in the front and rearward. Therefore, at the front end and the rear end, the surface joint is not elongated at the rear, and the recesses at the front end and the rear end disappear. By these procedures, the raw material yields of the front end and the rear end of the welding target materials 31a and 31b are improved.

(Fifth Embodiment) 5. After-pass mode (using joint material: first pole, rear pole simultaneous ignition)

The fifth embodiment also uses a two-electrode plasma torch 30 which is provided with an embedded tip 1 having two electrode arrangement spaces 2a, 2b and two nozzles 3a respectively communicating with the respective electrode arrangement spaces. 3b; as shown in FIG. 13, the front end joints 38a, 38b and the rear end joints 39a, 39b are disposed at the front end and the rear end of the welding target materials 31a, 31b, so that the arrangement direction of the two nozzles is parallel to the weld line. The two-electrode plasma torch 30 is driven while the welding target materials 31a and 31b are driven in the direction along the weld line, and a plasma arc is generated by the electrodes 12a and 12b located in the respective electrode arrangement spaces, and the weld line is applied. Welding.

The leading pole is set to preheat the plasma arc, and the trailing pole is set to penetrate the plasma arc. As shown in Fig. 16 (1), the light-emitting poles are at the front ends of the welding target materials 31a, 31b, and the rear rows are opposite to the positions of the front end joints 38a, 38b, and the leading and trailing poles are activated. The plasma arc starts the driving of the two-electrode plasma torch 30, as shown in Fig. 16 (3), as long as the trailing pole reaches the rear end of the welding target materials 31a, 31b, and ends the welding at the rear end, the respective stops are stopped. Extreme plasma arc. Fig. 17 is a basic diagram showing the welding current, the plasma gas flow rate, and the welding speed at the time points T1 to T4 at which the leading poles reach the respective positions shown in Figs. 16(1) to (4).

According to the fifth embodiment, from the front end of the welding target material 31a, 31b to the rear end, the material to be welded is preheated by the plasma of the leading electrode, and the surface seam having less depression can be obtained even if the high speed welding is performed. The productivity of welding is improved. As long as the trailing pole reaches the front end of the welding target materials 31a, 31b, the plasma arc current for switching the leading pole is increased, and the traveling driving speed is increased, so that the productivity of the welding is improved. When the first pole is located at the beginning of the welding target materials 31a, 31b and the trailing poles are opposite to the slits of the front end joints 38a, 38b, the plasma arc of the leading and trailing poles is activated, and the rear poles are located at the welding target materials 31a, 31b. At the rear end, when the leading end is opposite to the slit of the rear end joints 38a, 38b, the plasma arc of the leading and trailing poles is stopped, so that the welding of the material of the welding target is completed and the welding is performed. The flame and the plasma plasma of the leading pole are mutually restrained, and the front end and the rear end of the welding target material are not biased toward the rear and the rear side of the plasma flame, so that the front surface is adjacent to the rear and the rear end, and the surface joint is The rear does not form a slender, and the recess at the rear end disappears. By these procedures, the raw material yields of the front end and the rear end of the welding target materials 31a and 31b are improved.

In addition, with regard to the fourth and fifth embodiments, the leading and trailing poles are not simultaneously ignited and stopped at the same time, and each pole is located in the range of the back joint material, and can also be separately ignited, and when the poles are located The area of the back joint material can also be stopped separately. In addition, the back end of the fusion interface processing can also be performed at the back end.

(Modification of the first to fifth embodiments)

If the welding of the two-electrode plasma torch 30 is used, since the distance between the leading/rearing poles is short, according to the welding condition, as shown in Fig. 18(a), the melting pool formed by the prior penetration welding is melted. The metal will be sucked into the subsequent common welding plasma arc immediately below, between the penetration weld and the common weld A, there is molten metal flowing from the leading side to the rear side, at the end of the weld line, Sometimes the fusion is ended in a reduced thickness state. The thicker the board is, the more viscous the metal is. In order to avoid this phenomenon, the rear end of the welding target materials 31a, 31b is inclined at a lower posture than the front end, and the two-electrode plasma torch 30 is driven to be parallel to the weld line in a posture perpendicular to the surface of the welding target material 31a, 31b. The direction. In this manner, as long as the material to be welded is inclined, the force in the molten metal is applied to the molten metal in the molten pool by gravity, the suction is suppressed, and the thickness of the joint at the rear end is reduced, and the seam at the rear end portion is reduced. The surface becomes flat. The two-electrode plasma torch 30 has a vertical posture on the surfaces of the welding target materials 31a and 31b, so that it is easy to set or adjust the penetration welding conditions of the preceding poles and the common welding conditions of the trailing poles.

In any of the above-described first to fifth embodiments and the modifications, even if the back-end solution processing is performed in accordance with the material and the thickness of the sheet, when the thickness of the surface joint is large, the supply of the wire at the rear end portion can be compensated. . Although the above description shows the welding of the flat plates, the present invention is not limited thereto, and can be applied to the circumferential welding of the both ends of one of the tubular plates which are bent into a cylindrical shape, or the head welding, the overlapping angle thick welding, and the like. .

(Sixth embodiment)

In the sixth embodiment of the front end fitting device shown in Fig. 23, the plasma torch 30 bends the flat plate conveyed to the production line into a cylindrical shape, and welds the two sides of the original flat plate to the head, that is, the welded object. The material W (Fig. 26) is placed between the two sides (melt joints) behind the welded pair. The two-electrode plasma torch 30, in The plasma torch disclosed in Patent Document 1 has a built-in tip with two welding electrodes in the same body, and has two nozzles. A plasma arc is ejected from each nozzle, and the nozzle members 20a and 20b having nozzles are opposed to each other. The welded wire of the welding target material W (Fig. 27).

In the present embodiment, the second driving device 105 of the front end joint device is coupled to and supported by the plasma torch 30 by the connecting arm 104. The second drive unit 105 supports and supports the piston rod 106 and the guide rods 108 and 109 fixed to the support base 107 so as to advance and retract the piston rod 106. The first driving device 111 is fixed to the support base 107 through the pin 110. The first driving device 111 supports the support leg 112 in a freely traversing manner and performs horizontal driving. A copper front end joint 113 having a high thermal conductivity is fixed to the support leg 112.

Figure 24 (a) shows an enlarged view of the front end joint 113, Figure 24 (b) shows a view of separating the base 113b of the front end joint 113, and Figure 24 (c) shows that the base body will be covered. The back surface of the tongue portion 113p and the high magnetic permeability cover on both sides, that is, the cover 114 of the soft iron are separated. The front end joint 113 (Fig. 23, Fig. 24 (a)) is inserted into the groove 114r of the soft iron cover 114 shown in Fig. 24 (c), as shown in Fig. 24 (b). The tongue portion 113p of the copper substrate 113b having high thermal conductivity is fixed to be integrated. The base body 113b has a water-passing hole, and at one end and the other end of the water-passing hole, there is a nozzle for receiving cooling water and a nozzle for discharging cooling water, and cooling water is supplied from the water supply pipe, and then flows through the water-passing hole, and then discharged. The illustration of the components associated with the circulation of these cooling waters is omitted.

Referring again to Fig. 23, the tongue portion 113p (Fig. 24) covering the back surface and the two sides by the cover 114 made of soft iron at the end joint 113 in the standby position is located in the nozzle member 20a of the two-electrode plasma torch 30. , 20b is immediately below. The base 113b of the front end joint 113 passes through the support leg 112 and is suspended and supported by the first driving device 111. The first driving device 111 is a linear actuator that is generally referred to as a rodless cylinder. The movable magnet piston is used to divide the cylinder into two chambers, and a magnet holder that is strongly adsorbed to the piston is provided outside the cylinder. . The support leg 112 is fixed to the magnet carrier.

The chamber separated by the movable magnet piston is connected to the air pressure 埠, and the negative pressure solenoid valve (not shown) is opened, and the air enthalpy is connected to the negative pressure port of the air pressure source (not shown), thereby being fixed to The support leg 112 (front end joint 113) of the magnet carrier is driven to the standby position shown in FIG. The standby position sensor 111hs detects that the front end joint 113 is at the standby position. The open solenoid valve (not shown) is opened, and the air pressure 埠 is set to atmospheric pressure, whereby the front end joint 113 is pressed by the welding target material W and can be moved to the direction of the arrow y (Fig. 27). The set position sensor 111ts detects the set position in the direction of the arrow y. Before the set position, the end joint 113 opens the positive pressure solenoid valve (not shown), and connects the air pressure 埠 to the high pressure port of the air pressure source, thereby returning to the standby position (Fig. 23).

The second drive unit 105 is a linear actuator that is a linear drive of a cylinder. The inside of the cylinder is divided into two chambers by a piston, and the front end of the piston rod 106 coupled to the piston is led out to the outside of the cylinder. The support table 107 is fixed to the front end of the piston rod 106. The front ends of the two guide bars 108, 109 parallel to the piston rod 106 are fixed to the support base 107, and are supported by the frame of the second driving device 105 so as to be freely movable in the reciprocating direction of the piston rod 106. The reciprocating direction of the piston rod 106 is about 45 degrees with respect to the moving direction of the welding target material W (the thick line arrow on FIG. 26 and FIG.

The chamber divided by the piston to which the piston rod 106 is connected is connected to the air pressure port, and the high pressure solenoid valve (not shown) is opened, and the air pressure port is connected to the high pressure port of the air pressure source (not shown), thereby fixing The support table 107 having the piston rod 106 is driven to the action position shown in Fig. 23, Fig. 26, and Fig. 27, and the first drive position 111 is driven to The location of action. The action position sensor 105hs detects that the first drive position 111 is at the active position. The negative pressure solenoid valve (not shown) is opened, and the air pressure is connected to the negative pressure port of the air pressure source, whereby the support table 107 is driven to the retracted position shown in FIG. 28, and the first driving device 111 is Driven in the retracted position. The retracted position sensor 105ts detects that the first drive unit 111 is at the retracted position. When the first driving device 111 moves to the retracted position, the negative pressure solenoid valve is closed (OFF), thereby stopping the movement of the piston rod 106, and the first driving device 111 stays at the retracted position. The positive pressure solenoid valve is opened, and the air pressure is connected to the high pressure port of the air pressure source, whereby the first driving device 111 can return to the working position (Fig. 23, Fig. 26, Fig. 27).

Further, the first drive device 111 and the second drive device 105 are supplied with the electromagnetic valve group of the operation pressure, and the opening and closing instructions of the electromagnetic valve groups of the electromagnetic valve actuator and the electromagnetic valve group are supplied to the microcomputer of the solenoid valve driver ( The illustration of the programmer or controller is omitted.

Fig. 25 shows the drive control of the first and second driving devices 111 and 105 for controlling the position of the front end connector of the microcomputer. As long as the microcomputer instructs "initialization" according to the instruction of the upper computer or the operator, the ON button of the high voltage solenoid valve for the second driving device 105 and the negative pressure solenoid valve for the first driving device 111 are turned ON. The indication is provided to the electromagnetic drive. Then, wait for the fusion indication signal from the upper computer. This state is shown in Fig. 23. The lower and side tongue portions 113p (Fig. 24(a)) are covered by the soft iron cover 114 of the front end joint 113 in the two-electrode plasma torch 30. The nozzle members 20a and 20b are immediately adjacent to the "standby state".

The welding target material W transferred from the production line comes, and when the front end is located at the front end of the front end connector 113 (the front end of the tongue portion 113p), the upper computer transmits the welding indication signal to the microcomputer, and after responding to the instruction, the microcomputer advances. Pole-start penetration welding The plasma arc and the plasma arc that is commonly fused by the back row (T11, Figure T26, Figure 26). The welding target material W moves while pressing the front end joint 113, whereby the plasma arc welds the welding target material W. After the front end of the welding target material W is passed immediately behind the nozzle member (20b), as shown in Fig. 29, the magnetic flux induced by the two arcs flows through the front cover of the high-permeability soft iron cover 114. Divided toward the front, so the force in the opposite direction to the material transfer direction (y arrow direction) of the welding target material applied to the trailing plasma arc PA-T becomes smaller, and the transverse direction of the plasma arc PA-T (Fig. 30) As the size becomes smaller, the weld seam at the beginning of the fusion is flattened.

When the welding target material W is pressed against the front end of the front end joint 113 while passing through the lower range of the two-electrode plasma torch 30 (T12, Fig. 27), the microcomputer supplies the negative pressure to the second driving device 105, which will be the first The drive unit is driven to the retracted position (Fig. 28). When the retracted position is reached, the air pressure is closed from the negative pressure port of the air pressure source, and the retracted position is maintained (T13). Then, when the terminal of the welding target material W passes through the preceding nozzle member 20a, the preceding plasma arc is released, and when passing through the nozzle member (20b), the subsequent plasma arc is released, and the terminal of the welding target material W waits for passage. The front end joint 113 is immediately below. When it passes, the retracted position of the first drive unit 111 is released (T14), the first drive unit 111 is returned to the operation position (T15), the high voltage is supplied to the first drive unit 111, and the front end joint 113 is returned to the standby position (T16). , Figure twenty-three). Then, wait for the next splice object material to arrive.

As described above, the front end joint 113 is placed at the standby position, and the welding target material W is conveyed, and when the welding target material W abuts against the front end surface of the front end joint 113, the welding arc is started, so that the two-electrode plasma torch 30 and the front end are A plasma welding arc is generated between the joints 113, and the stability of the plasma arc starting is high. After the plasma arc is started, the front end joint is pushed to the retracted position by welding the material of the object, as long as the front end joint 113 When the front end face is separated from the two-electrode plasma torch 30, the front end joint 113 is driven to the retracted position. After the drive to the retracted position, the front end joint 113 is returned to the standby position by the end of the welding of the welding target material W, and the next welding target material is awaited, and the welding target material is welded in the same manner. In this way, the start of the plasma welding arc is stable, and continuous production of most short strip products can be performed with high efficiency.

The light arc penetration welding and the subsequent common welding of the plasma arc of the above-mentioned two-electrode 2 nozzle are used, and the back surface and the side surface of the tongue portion 113p are covered with a cover 114 made of a high magnetic permeability soft iron, and the tongue portion 113p is attached. The plasma arcs PA-L, PT-T of the base 113b of the front end joint 113 are activated, so that the sinking seam sinking of the material of the welding target material by the trailing plasma arc PT-T is suppressed.

Further, in the sixth embodiment, the front end joint device is supported by the two-electrode plasma torch 30. However, when the two-electrode plasma torch 30 is stationary and fixed, and the material to be welded is moved relative to the two-electrode plasma torch 30, the front end joint The device can also be separated from the two-electrode plasma torch 30 and independently stationary. Conversely, if the two-electrode plasma torch 30 is moved along the stationary welding target material, as in the sixth embodiment, the two-electrode plasma torch 30 is equipped with a front end fitting device, along with the two-electrode plasma. The torch 30 moves together, but it is preferable to suppress the addition of the drive mechanism. However, there is also a state in which the front end connector device is separated from the two-electrode plasma torch 30, and the front end connector device (the second driving device 105) and the two-electrode plasma torch 30 are separated by a driving mechanism attached to the front end connector. Move sync to drive in the same direction.

1‧‧‧Embedded pointed

1a, 1b‧‧‧ sloped surface

1c‧‧‧ front end projection

1d, 1e‧‧‧ front plane

1f, 1g‧‧‧ water circulation hole

1h‧‧‧ water hole

1i‧‧‧ water hole

1j, 1k, 1l‧‧‧ transverse water holes

2a~2d‧‧‧electrode configuration space

3a~3d‧‧‧ nozzle

5‧‧‧ pointed table

6‧‧‧ inner cover

7‧‧‧Insulated body

8‧‧‧Shield

9a, 9b‧‧‧ positioning stone

10a, 10b‧‧‧ electrode table

11‧‧‧Insulation gasket

12a, 12b‧‧‧ electrodes

13a, 13b‧‧‧ compression screws

14‧‧‧Outer tube

15a, 15b‧‧‧Ignition gas pipe

16a, 16b‧‧‧ water flow tube

18a, 18b‧‧‧ nozzle member insertion hole

19a, 19b‧‧‧ Plasma arc

20a~20d‧‧‧Nozzle components

21a~21d‧‧‧ Umbrella Department

22a~22d‧‧‧ cadres

23a~23d‧‧‧O-ring

24a~24d‧‧‧ male screw

25a, 25d‧‧‧ nuts

26a~26d‧‧‧cut surface

30‧‧‧Two-electrode plasma torch

31a, 31b‧‧‧ welding material

31p‧‧·melting pool

32a, 32b‧‧‧fused power-gas supply

33a, 33b‧‧‧ Plasma arc power supply

34a, 34b‧‧‧ ignition power

35‧‧‧Parallel operation control panel

36‧‧‧Torque walking motor

37‧‧‧Working motor for workpiece

38a, 38b‧‧‧ front connector

39a, 39b‧‧‧ Rear connector

104‧‧‧ Linking arm

105‧‧‧The second drive unit of the front joint drive

105hs‧‧‧Action position sensor

105ts‧‧‧Retraction position sensor

106‧‧‧Piston rod

107‧‧‧Support table

108, 109‧‧‧ Guides

110‧‧‧ pins

111‧‧‧First drive unit for front joint drive

11hs‧‧‧ Standby position sensor

111ts‧‧‧Set position sensor

112‧‧‧Support feet

113‧‧‧ front joint

113b‧‧‧ base (high heat conductor)

113p‧‧‧ tongue parts

114‧‧‧High permeability cover is a cover made of soft iron

114r‧‧‧ trench

Figure 1 (a) is a block diagram showing an example of a system configuration of a welding device for performing the welding method of a two-electrode plasma torch of the present invention, showing a material to be welded 31a, 31b. The two-electrode plasma torch 30 is driven to travel. Fig. 1(b) is a block diagram showing the state in which the welding target materials 31a and 31b are driven to travel in the two-electrode plasma torch 30.

Figure 2 is an enlarged view of the longitudinal section y-z of the two-electrode plasma torch 30 shown in Figure 1.

Figure 3 is an enlarged view of the longitudinal section x-z of the two-electrode plasma torch 30 shown in Figure 1.

Figure 4 (a) is a bottom view of the front end of the two-electrode plasma torch 30 shown in the direction of the IVa-IVa line, bottom view two, and Figure 4 (b) is the bottom view of the IVb-IVb line shown in Figure 3. The bottom view of the front end of the two-electrode plasma torch 30 is shown, and FIG. 4(c) is a cross-sectional view of the front end of the two-electrode plasma torch 30 shown in the second direction of the IVc-IVc line.

Figure 5 (a) shows the longitudinal section of the embedded tip and the inner cover 6 of the front end of the plasma torch shown in Figure 2 removed from the torch body. Figure 5 (b) shows only Figure 5 (a). FIG. 5(c) is a view showing the nut 25a, 25b shown in FIG. 5(a) removed from the nozzle member 20a, 20b, from the nozzle member 20a, 20b, from the longitudinal direction of the tip base 1 and the inner cover 6. The tip base of the tip 1 pulls out the nozzle member while indicating the front view (appearance view) of the nuts 25a, 25b.

Fig. 6 (a1) is a longitudinal sectional view of the nozzle member 20a shown in Fig. 5 (c), and Fig. 6 (a2) is a bottom view of the nozzle member 20a. 6(b1) is a longitudinal cross-sectional view of the nozzle member 20c according to the first modification of the tip base of the embedded tip 1, in place of or in place of one or both of the nozzle members 20a and 20b shown in FIG. Figure 6 (b2) is a bottom view of the nozzle member 20c. Figure 6 (c1) is a spray of a second variant of the tip base of the embedded tip 1 in place of one or both of the nozzle members 20a, 20b shown in Figure 2 A longitudinal sectional view of the nozzle member 20d, and Fig. 6(c2) is a bottom view of the nozzle member 20d.

Fig. 7 is a view showing the relative position of the welding material 31a, 31b of the two-electrode plasma torch 30 when the welding method of the first embodiment of the present invention is carried out by using the welding device shown in Fig. 1(a), Fig. 7 (1) ) indicates that the row electrode is placed at the front end of the welding target material 31a, 31b after the penetration welding, and the position where the welding is started, and Fig. 7 (2) indicates the position where the preheating is performed before the welding is started. The rear row pole reaches the relative position, and Fig. 7 (3) indicates the position of the stable welding state, and Fig. 7 (4) indicates the position where the leading pole is about to reach the front end of the welding target material 31a, 31b, Fig. 7 (5) The position indicating that the trailing pole reaches the rear end of the welding target materials 31a and 31b, and FIG. 7(6) indicates the position at which the driving is stopped after the welding is completed.

FIG. 8 is a timing chart showing the point at which the welding current and the plasma gas of the welding method according to the first embodiment of the present invention are switched to the timing at which the supply of the leading and trailing poles is switched, and the stop point and the stop of the welding travel (speed). Summary (Basic Graphics), the time points T1~T4 are the positions of the first row corresponding to the positions shown in Figure 7 (3) to Figure 7 (6).

Fig. 9 is a view showing the relative position of the two-electrode plasma torch 30 to the welding target materials 31a and 31b when the welding method of the second embodiment of the present invention is carried out by using the welding device shown in Fig. 1(a). The system indicates that the pre-heating pre-heating electrode is placed at the beginning of the welding target materials 31a, 31b to start the welding, and FIG. 9 (2) shows that the row electrode reaches the front end of the welding target material 31a, 31b after the penetration welding. Position, Fig. 9 (3) indicates the position of the stable welding state, Fig. 9 (4) indicates the position of the rear and rear rows reaching the rear end of the welding target materials 31a, 31b, and Fig. 9 (5) indicates that after the welding is completed, Stop the position of the drive.

Figure 10 is a timing chart showing the welding current of the welding method of the second embodiment of the present invention and the stopping point of the plasma gas to the leading and trailing poles and the welding (speed) stop. The outline of the stop point (basic figure), the time points T1~T3 are the positions of the first line corresponding to the positions of Fig. 9 (3) to Fig. 9 (5).

Figure 11 is a view showing the relative position of the welding material 31a, 31b of the two-electrode plasma torch 30 when the welding method of the third embodiment of the present invention is carried out by using the welding device shown in Fig. 1(a), Fig. 11 (1) indicates that the leading electrode for performing penetration welding is placed at the front end of the welding target materials 31a and 31b, and the welding is started. FIG. 11(2) shows that the row electrode reaches the welding target material 31a, 31b after the preheating is performed. The position of the front end, Fig. 11 (3) shows the position of the stable welding state, and Fig. 11 (4) shows the position where the leading pole is about to reach the rear end of the welding target materials 31a, 31b, and Fig. 11 (5) shows The row is about to reach the position of the rear end of the welding target materials 31a and 31b, and Fig. 11(6) shows the position where the driving is stopped after the welding is completed.

Figure 12 is a timing chart showing the summary of the welding current and the point at which the plasma gas is switched to the leading and trailing poles of the welding method according to the third embodiment of the present invention, and the point at which the welding speed is switched. (Basic graphics), the time points T1~T4 correspond to the positions of Figure 9 (3) ~ Figure 9 (6).

Figure 13 is a view showing the relative position of the welding material 31a, 31b of the two-electrode plasma torch 30 when the welding method of the present invention is carried out by using the welding device and the front end and the rear end joint shown in Fig. 1(a). The third (a) indicates the cross section of the weld line at the point of starting the welding, and the figure (b) shows the plane of the weld line (the surface of the material to be welded). Figure 13 (c) shows the cross section of the weld line at the end of the welding.

Figure 14 is a view showing the relative position of the two-electrode plasma torch 30 to the welding target materials 31a, 31b when the welding method of the fourth embodiment of the present invention is carried out by using the welding device shown in Fig. 1(a). (1) indicates that the preceding pole that performs the penetration welding is placed at the front end of the welding target materials 31a, 31b, and the position where the welding is started is shown in Fig. 14 (2) It is shown that the position where the row electrode reaches the front end of the welding target materials 31a and 31b after the preheating is performed, and the position of the leading end of the preheating is relatively opposite, and Fig. 14(3) shows the position of the stable welding state, Fig. 14(4) The position indicating that the trailing pole reaches the rear end of the welding target materials 31a and 31b, and FIG. 14(5) shows the position at which the traveling drive is stopped after the welding is completed.

Figure 15 is a timing chart showing the summary of the welding current and the plasma gas supply to the preceding pole and the rear row, the timing of switching the stop point and the supply amount, and the switching point of the welding speed in the welding method according to the fourth embodiment of the present invention. (Basic graphics), the time points T1 to T3 correspond to the time points T1 to T3 shown in Fig. 14.

Figure 16 is a view showing the relative position of the two-electrode plasma torch 30 to the welding target materials 31a, 31b when the welding method of the fifth embodiment of the present invention is carried out by using the welding device shown in Fig. 1(a). 1) indicates that the leading electrode for common welding is placed at the front end of the welding target material 31a, 31b, and the position where welding is started, and Fig. 16 (2) indicates the position of the stable welding state, and Fig. 16 (3) indicates that the position is performed. After the penetration welding, the row electrode reaches the position of the rear end of the welding target materials 31a, 31b, and Fig. 16 (4) shows the position where the driving is stopped after the welding is completed.

Figure 17 is a timing chart showing an outline (basic pattern) of the welding current and the point at which the plasma gas is stopped at the leading and trailing poles and the stop of the welding walking in the welding method according to the fifth embodiment of the present invention, at a time point T1~ The T4 series corresponds to the positions of (1) to (4) shown in Fig. 16 respectively.

Fig. 18(a) is a cross-sectional view showing a portion of the weld line in a state in which the molten metal of the molten pool of the penetration pole is sucked into the molten pool of the common electrode of the succeeding electrode. Fig. 18 (b) is a cross-sectional view showing a welded portion where the welding target materials 31a and 31b and the two-electrode plasma torch 30 are inclined downward in order to prevent suction.

Figure 19 (a) shows the pre-heating of the pre-heating pole, after the penetration welding When the row electrode is separated, the rear end electrode is placed at the front end of the welding target materials 31a and 31b, and when the welding is started simultaneously with the leading electrode, a cross-sectional view of the preheating time lag (preheating insufficient range) of the tip end portion of the welding target material is performed. Fig. 19(b) is a side view showing the range (permanent) of penetration penetration due to the preheating time lag with a broken line.

Figure 20 (a) shows that, according to the present invention, the rear end joint is disposed at the rear end of the welding target material 31a, 31b, and the plasma flame of the rear end electrode is located between the welding target material ranges, when the plasma flame of the leading electrode is located When the range of the end fittings 39a, 39b is removed after the welding target material is removed, the plasma arc of the first electrode is further advanced, and the longitudinal position of the relative position of the welding material 31a, 31b of the two-electrode plasma torch 30 is shown in Fig. 20(b) It is a cross-sectional view showing the welded joint of the BB line section in Fig. 20(a).

Figure 21 (a) shows the longitudinal section of the plasma flame interaction between the leading and trailing poles of the two-electrode plasma torch 30 between the front and rear ends of the welding target materials 31a, 31b. Figure 21 (b) shows a plan view of the magnetic flux distribution induced by the material of the welding target by the plasma flame of the leading and trailing poles. Figure 21 (c) shows Figure 21 (a) A cross-sectional view of the welded joint of the CC line section above.

Figure 22 (a) shows that the two-electrode plasma torch 30 reaches the rear end of the material to be welded without the rear end joint. Since the front end removes the rear end, the plasma arc of the leading pole is stopped. A longitudinal section of the welding target material 31a, 31b and the two-electrode plasma torch 30 when the plasma flame is biased rearward, and FIG. 22(b) shows that the material of the welding object is sensed by the plasma flame of the trailing pole. A plan view of the flux distribution, and Fig. 22(c) shows a cross-sectional view of the welded joint in which the CC line section of Fig. 22(a) has a depression.

Figure 23 is a side view of the front end fitting device used in the sixth embodiment of the present invention The material of the welding target is parallel to the paper surface of Fig. 23 and is transported from left to right (in the direction of the y arrow).

Figure 24 (a) shows a perspective view of the front end joint 113 shown in Figure 23, and Figure 24 (b) and Figure 24 (c) show a perspective view of the front end joint 113. Twenty-four (b) shows the base 113b (high thermal conductor) of the front end joint 113, and Fig. 24(c) shows that the high magnetic permeability cover which covers the lower surface of the protruding tongue portion 113p of the base 113b and both sides is soft. Iron cover 114.

Fig. 25 is a timing chart showing the operation of the front end fitting device shown in Fig. 23.

Figure 26 shows that the front end face of the front end joint 113 before the end joint device shown in Fig. 23 abuts the two-electrode plasma torch 30 of the front end face of the welding target material W conveyed in the y direction, and the arc moment is started. Side view.

Figure 27 shows the moment when the front end of the front end joint 113 is detached from the immediately below the two-electrode plasma torch 30 by the plasma arc that is activated, and the side end of the front end joint device shown in Fig. .

Fig. 28 is a side view showing a state in which the front end fitting 113 of the front end fitting device shown in Fig. 23 is placed at the retracted position.

Figure 29 (a) shows the shape and magnetic flux distribution of the trailing plasma arc PA-T when the front end of the welding target material W is opposite to the downstream nozzle member 20b as shown in Fig. The enlarged longitudinal section of the outline is shown in Fig. 29. (b) is an enlarged plan view.

Fig. 30 (a) shows the low magnetic permeability front end joint 113 of the cover 114 made of soft iron, which is a cover having a high magnetic permeability, when the end portion of the welding target material W is opposed to the lower nozzle member 20b. An enlarged longitudinal sectional view showing the shape of the trailing plasma arc PA-T and a summary of the magnetic flux distribution, and FIG. 30(b) is an enlarged plan view.

20a, 20b‧‧‧ nozzle components

30‧‧‧ Plasma Torch

31a, 31b‧‧‧welding

39a, 39b‧‧‧ Rear connector

Claims (19)

A welding method using a two-electrode plasma torch, which uses a two-electrode plasma torch, and is provided with an embedded tip having two electrode arrangement spaces and two nozzles respectively communicating with each electrode arrangement space Aligning the two nozzles in parallel with the weld line, and causing at least one of the two-electrode plasma torch and the welding target material to be driven while traveling along the weld line, while being disposed in each non-consumable electrode arrangement space Each of the electrodes generates a plasma arc, and the weld line is welded, and is characterized in that, immediately below the plasma flame, a water-cooled copper joint opened by a slit or a groove is formed, and the rear end joint is disposed on the welding target material. At the rear end of the direction, in the extending direction of the weld line, the pre-heating plasma arc is generated by the leading non-consumable electrode (ie, the leading electrode), and the non-consumable electrode (ie, the rear electrode) is used to generate a penetrating plasma arc, or A penetrating plasma arc is generated by the leading pole, and a common plasma arc is generated by the trailing pole, and the trailing electrode ends the welding at the rear end until the plasma arc is stopped, and continues The first step is the plasma arc. The welding method of the two-electrode plasma torch according to the first aspect of the invention, wherein the plasma arc of the preceding and succeeding poles is stopped when the welding of the front end and the rear end is ended by the rear end pole, Thereafter, the aforementioned travel drive is stopped. The welding method of the two-electrode plasma torch according to the first aspect of the invention, wherein the welding target material and the rear end joint are inclined at a lower end than the front end of the welding target material, so that the walking is performed. The drive becomes parallel to the weld line. The method of welding a two-electrode plasma torch according to claim 3, wherein the two-electrode plasma torch is perpendicular to a posture of a surface of the material to be welded. A welding method using a two-electrode plasma torch according to any one of the preceding claims, wherein the preceding pole is set in a plasma arc that generates a material for preheating the welding target, The electrode is set in the plasma arc of the penetration welding. When the row electrode is located before the front end of the material of the welding target after the penetration welding, the plasma arc of the penetration welding is started by the rear pole, and the plasma of the preceding electrode is The arc is activated at the same time as the plasma arc of the penetration weld or before it is generated, and the aforementioned travel drive is started at the same time as or after the start of the plasma arc. A welding method using a two-electrode plasma torch according to any one of claims 1 to 4, wherein the preceding pole is set in a plasma arc for penetration welding, and the rear row is set In the plasma arc of the common fusion welding line, when the preceding pole of the penetration welding is set before the front end of the welding target material, the plasma arc of the penetration welding of the preceding pole is activated, and the plasma arc of the rear row is performed. The start is initiated at the same time as the plasma arc of the penetration weld is initiated or at the front end of the material of the welding target, and the aforementioned travel drive is started at the same time as or after the start of the plasma arc. A welding method using a two-electrode plasma torch according to claim 5, wherein when the trailing pole is located at a front end of the material to be welded, the plasma arc of the preceding and trailing poles is simultaneously activated, and At the same time of starting, the aforementioned driving is started at a low speed, and as long as the trailing pole reaches the position of the preceding pole to start the plasma arc, the traveling drive is switched at a high speed, and the plasma arc current and electricity of the row after switching are improved. Two or one of the slurry gas flows, Before the leading pole is about to reach the end of the welding target material, the plasma arc current and the plasma gas flow of the preceding pole are reduced, or the traveling drive is driven as long as the trailing pole reaches the rear end. The speed is reduced, and either or both of the plasma arc current and the plasma gas flow of the trailing pole are lowered, and the plasma arc of the leading and trailing poles is stopped after the processing of the melt interface of the trailing pole. A welding method using a two-electrode plasma torch according to claim 5, wherein when the preceding pole is located at a front end of the material to be welded, the walking is started at a low speed while starting the plasma arc of the leading electrode Driving, as long as the trailing pole reaches the front end of the welding target material, the plasma arc of the rear row is activated, and when the through-going pole is formed through the welding, the traveling drive is switched at a high speed, and the switching pole is improved. Two or one of a plasma arc current and a plasma gas flow. A welding method using a two-electrode plasma torch according to claim 6, wherein when the preceding pole is located at a front end of the welding target material, the walking is started at a low speed while starting the plasma arc of the leading electrode Driving, as long as the trailing pole reaches the front end of the welding target material, the plasma arc of the rear row is started, and as long as the trailing pole reaches the front end of the welding target material, the traveling drive is switched at a high speed, and the switching leading pole is improved. The plasma arc current and the plasma gas flow rate are both reduced or reduced by either or both of the plasma arc current and the plasma gas flow before the leading electrode reaches the end of the welding target material. And switching the aforementioned travel drive at a low speed, at the back end, stopping the leading and trailing poles Plasma arc. A two-electrode plasma torch welding method according to any one of claims 1 to 4, wherein the water is cooled by a slit or a groove at a position immediately below the plasma flame. The copper joint constitutes a front end joint disposed at a front end of the welding target material in the welding direction, and when the leading and trailing poles are located before the front end of the welding target material, the plasma arc is simultaneously started at both poles. The welding method using a two-electrode plasma torch according to the fourth aspect of the patent application, wherein the aforementioned driving is started as long as the plasma arc is simultaneously started at both poles. The welding method of the two-electrode plasma torch according to claim 10, wherein the preceding pole is set in the plasma arc of the penetration welding, and the rear row is set to the plasma of the common fusion welding line. When the arc is set before the front end of the penetration welding material is located before the front end of the welding target material, the plasma arc of the penetration welding is started by the preceding pole, and the plasma arc of the rear pole is activated to penetrate the welding plasma. The arcing is simultaneously performed at the same time as the front end of the material to be welded, and the aforementioned driving is started at the same time as or at the same time as the plasma arc is started. A welding method using a two-electrode plasma torch according to claim 10, wherein the preceding pole is set in a plasma arc for generating a material for preheating welding, and the rear row is set in penetration welding. a plasma arc, when the row electrode is located before the front end of the material to be welded after the penetration welding, the plasma arc of the penetration welding is initiated by the rear pole, and the plasma arc of the preceding pole is penetrated and welded. Simultaneously starting or before the plasma arc, simultaneously or simultaneously starting the plasma arc or After starting, the aforementioned travel drive is started. According to the welding method of the two-electrode plasma torch according to the first aspect of the patent application, in the welding, in the relative movement of the material of the two-electrode plasma torch and the welding target, the front end face of the front end joint is opposite to the material of the welding target material. a starting end, wherein the front end face is opposite to the front end of the two-electrode plasma torch, and the standby position is started from the welding arc, and the front end surface is separated from the two-electrode plasma torch and the welding target material in the direction of the relative movement a retracting position, and conversely, movably supporting the joint, wherein the front end joint is placed in the standby position by driving the front end joint driving means, and the front end of the welding target material in the relative moving direction abuts on the front end At the front end of the front end joint, or immediately before or after the abutment, the plasma arc is started at the leading and trailing ends. The method of welding a two-electrode plasma torch according to the fourteenth aspect of the invention, wherein the front end joint driving means comprises: a first driving device, wherein the front end connector is in the direction of the relative movement from the standby position The front end face is separated from the set position of the two-electrode plasma torch, and conversely, the front end joint is movably supported and driven; and the second driving device is configured such that the front end connector connects the first driving device from the standby position Driven at the set position, or vice versa, from the driven position, the front end joint is driven to the inactive position of the retracted position, or conversely movably supported and driven. A welding method using a two-electrode plasma torch according to the fifteenth aspect of the invention, wherein the first driving device and the second driving device each include a cylinder. The method of welding a two-electrode plasma torch according to claim 14, wherein the front end joint is covered with a high magnetic permeability cover The high thermal conductivity substrate is at least under the front end of the beginning of the welding target material. A welding method using a two-electrode plasma torch according to claim 17, wherein the two-electrode plasma torch is equipped with the front end joint device. The method of welding a two-electrode plasma torch according to claim 14, wherein the front end joint is placed in the standby position, and the front end of the material to be welded is abutted against the front end surface of the front end joint or Before it is about to abut or immediately after the contact, a plasma arc that penetrates the fusion is started between the preceding leading pole and the front end joint, and the common between the rear row pole and the front end joint is started. a welding arc of the welding, wherein the front end of the welding target material is immediately adjacent to the two nozzles, and the front end surface of the front end joint does not interfere with the position of the plasma torch, and the front end joint is driven to the retracted position as long as the welding is performed When the terminal of the target material is separated from the plasma arc, the plasma arc is stopped, and thereafter, the material to be welded is moved to the standby position of the front end joint, and moved to a position where no interference occurs, and the front end joint is placed at the standby position.