JP2013043181A - Welding torch, and plasma welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding torch and a plasma welding method, achieving a reduction in costs required for plasma welding and also achieving easy plasma welding.SOLUTION: This welding torch includes: an inner member 11 which has an electrode 24 including a tip end 24A supplied with pilot gas, and a collet 22 for regulating the position of the electrode 24A with respect to the axial direction A of the electrode 24 so as to expose the tip end 24A of the electrode 24; an outer member 12 which has a center nozzle 27 for storing at least a part of the tip end 24A of the electrode 24, an outer nozzle 31 arranged outside of the center nozzle 27, and a shielding gas flow passage 33 for guiding shielding gas toward the tip end surface 27a of the center nozzle 27, and which is arranged to surround a part of the periphery of the inner member 11; and a drive section 14 for relatively moving the inner member 11 and outer member 12 to the axial direction A of the electrode 24.

Description

  The present invention relates to a welding torch and a plasma welding method capable of plasma welding a work piece without using a pilot arc generator.

  Conventionally, welding of structures (workpieces) using metals and non-ferrous metals as a base material uses welding methods using non-consumable electrodes such as plasma welding and TIG welding (Tungsten Inert Gas welding). It has been.

FIG. 9 is a diagram for explaining a conventional plasma welding method, and FIG. 10 is a diagram for explaining a conventional TIG welding method.
Referring to FIG. 9, in the plasma welding method, a pilot arc is generated between the electrode 101 and the center nozzle 102, and then welding is performed by switching the current flow to the workpiece 104.

Here, the principle of the plasma welding method will be described with reference to FIG.
First, a low current arc (referred to as “pilot arc”) is formed between the electrode 101 (tungsten electrode) and the water-cooled center nozzle 102 using a high-frequency generator (equipment incorporated in the pilot arc generator 105). ).

  The inert gas in the center nozzle 102 or the pilot gas in which hydrogen is added to the inert gas is ionized by this arc heat, becomes a good conductor of the arc current, and the current flow is switched to the work piece 104 side, A main welding arc is generated between the electrode 101 and the workpiece 104.

  This ionized gas is called plasma, and is ejected as a plasma jet when passing through an orifice (a hole having a diameter of several millimeters) provided in the center nozzle 102. The arc guided to the plasma jet is tight and dense. For this reason, since it is hotter than a normal TIG welding method, the workpiece 104 can be melted more.

  Incidentally, in the welding torch 110 used for TIG welding shown in FIG. 10, the tip 111 </ b> A of the electrode 111 protrudes from the tip of the center nozzle 113. Accordingly, since the distance between the tip 111A of the electrode 111 and the workpiece 115 is short, a pilot arc generator for generating a pilot arc is not necessary.

  On the other hand, as shown in FIG. 9, in the welding torch 100 used for plasma welding, the tip 101 </ b> A of the electrode 101 is accommodated in the center nozzle 102. As a result, the distance between the tip 101 </ b> A of the electrode 101 and the workpiece 104 is increased, so that the arc cannot reach the workpiece 104.

  Therefore, when plasma welding is performed, an expensive pilot arc generator 105 including a pilot arc power source 107 and a power source switching device 108 is required, which increases the cost required for plasma welding.

  Patent Document 1 also has a plasma arc torch body having a double shield structure having an axial gas passage at the center and a secondary gas passage on the outer periphery thereof, and is detachable from the plasma arc torch body. There is disclosed a plasma arc TIG welding combined torch configured to serve both as a plasma arc torch and a TIG welding torch by replacing a replacement part attached to the machine.

Japanese Utility Model Publication No. 56-126981

By the way, in the welding torch described in Patent Document 1, plasma welding and TIG welding are performed by replacing replacement parts.
Therefore, when plasma welding is performed using the welding torch described in Patent Document 1, the expensive pilot arc generator 105 shown in FIG. 9 is required, which increases the cost required for plasma welding. .

  That is, when performing the conventional plasma welding using the configuration shown in FIG. 9 and the plasma welding using the welding torch described in Patent Document 1, there is a problem that the cost required for the plasma welding increases.

  Moreover, the price of a plasma welding machine is very expensive, about 6 to 7 times the price of a TIG welding machine, and is not very popular. That is, it is difficult to easily weld the workpiece using the plasma welding method.

  Therefore, an object of the present invention is to provide a welding torch and a plasma welding method capable of reducing the cost required for plasma welding and easily performing plasma welding.

  In order to solve the above-described problem, according to the invention according to claim 1, an electrode including a tip portion to which a pilot gas is supplied, an outer periphery of the electrode so as to expose the tip portion of the electrode, and the electrode An inner member having a collet that regulates the position of the electrode with respect to the axial direction of the electrode, a center nozzle that houses at least a part of the tip of the electrode, and an outer side of the center nozzle so as to be separated from the center nozzle An outer nozzle disposed, and a shield gas passage formed between the center nozzle and the outer nozzle for guiding a shield gas toward the tip of the center nozzle, and an outer peripheral portion of the inner member An outer member disposed so as to surround a part, and the inner member and the outer with respect to an axial direction of the electrode. Welding torch, characterized in that it comprises a driving unit for relatively moving member, is provided.

  According to the invention of claim 2, the tip of the electrode protrudes from the tip surface of the center nozzle as the inner member and the outer member move relative to the axial direction of the electrode. The welding torch according to claim 1, wherein the welding torch is housed in the center nozzle.

  According to the invention of claim 3, the driving portion is provided in a portion of the outer peripheral portion of the inner member that is exposed from the outer member and extends in the axial direction of the electrode. The welding torch according to claim 1, further comprising: a pinion that engages with the rack and rotates to move the inner member in the axial direction of the electrode.

  Moreover, according to the invention which concerns on Claim 4, the said outer member is being fixed to the welding torch support member, The welding torch of Claim 3 characterized by the above-mentioned is provided.

  According to the invention of claim 5, the welding torch according to any one of claims 1 to 4 is provided, wherein the electrode is a non-consumable electrode.

  The invention according to claim 6 is the plasma welding method using the welding torch according to any one of claims 1 to 5, wherein the tip of the electrode is moved from the tip surface of the center nozzle. A step of generating an arc between the tip of the electrode and the work piece by causing the pilot gas to flow, and after generating the arc, the tip of the electrode is accommodated in the center nozzle. And a step of welding the workpiece by flowing a shielding gas. A plasma welding method is provided.

  According to the present invention, an electrode including a tip portion to which a pilot gas is supplied, and a collet that is disposed on the outer periphery of the electrode so as to expose the tip portion of the electrode and regulates the position of the electrode with respect to the axial direction of the electrode. An inner member, a center nozzle that accommodates at least a part of the tip of the electrode, an outer nozzle that is disposed outside the center nozzle so as to be separated from the center nozzle, and the center nozzle and the outer nozzle are formed. An outer member disposed to surround a part of the outer peripheral portion of the inner member and an inner member with respect to the axial direction of the electrode, and having a shield gas flow path for guiding the shield gas toward the tip of the center nozzle And a drive unit that relatively moves the outer member, so that the tip of the electrode from the tip surface of the center nozzle By allowing the pilot gas to flow by projecting, it becomes possible to generate an arc (pilot arc) between the tip of the electrode and the work piece, and after generating the arc, the tip of the electrode is placed inside the center nozzle. The object to be welded can be plasma-welded by flowing the shielding gas in the container.

  This eliminates the need for an expensive pilot arc generator (apparatus for generating a pilot arc) that was necessary when plasma welding a workpiece to be welded using a conventional plasma welding torch. The cost when performing the process can be reduced.

  Moreover, plasma welding can be easily performed by attaching a welding torch including an inner member, an outer member, and a drive unit to a TIG welding machine having a higher penetration rate than a plasma welding machine. .

It is sectional drawing which shows schematic structure of the welding torch concerning embodiment of this invention. It is sectional drawing which shows typically the state of the welding torch at the time of rotating the pinion of the welding torch of the state shown in FIG. 1 counterclockwise. It is sectional drawing which shows typically the state of the welding torch at the time of rotating clockwise the pinion of the welding torch of the state shown in FIG. It is FIG. (1) for demonstrating the other application example of the welding torch of this Embodiment. It is FIG. (2) for demonstrating the other application example of the welding torch of this Embodiment. It is a figure for demonstrating the positional relationship of the front-end | tip surface of the center nozzle at the time of welding of Example 1, and the front-end | tip of an electrode. It is a figure for demonstrating the positional relationship of the front-end | tip surface of the center nozzle at the time of performing welding of Example 2, and the front-end | tip of an electrode. It is a figure which shows the cross-sectional photograph after welding of Example 1 and a comparative example, and a penetration depth. It is a figure for demonstrating the conventional plasma welding method. It is a figure for demonstrating the conventional TIG welding method.

(Embodiment)
FIG. 1 is a cross-sectional view showing a schematic configuration of a welding torch according to an embodiment of the present invention.
Referring to FIG. 1, the welding torch 10 of the present embodiment includes an inner member 11, an outer member 12, a fixing portion 13, and a driving portion 14.
The inner member 11 includes a heat-resistant insulating member 15, a collet body 16, a torch head 18, a torch cap 21, a collet 22, and an electrode 24.

The heat-resistant insulating member 15 is a cylindrical member, and has a first engagement portion 15A that engages with the collet body 16 on the inner wall located on the lower end side.
The collet body 16 is a cylindrical member and is inserted into the heat-resistant insulating member 15. The collet body 16 has a distal end portion 16A, a second engagement portion 16B, a third engagement portion 16C, and a pilot gas passage hole 16a.

  The tip portion 16A is provided at the lower end portion of the collet body 16 (in other words, the portion located on the tip portion 24A side of the electrode 24), and has a shape such that the inner diameter becomes narrower toward the tip 24a of the electrode 24. Has been.

  The second engagement portion 16B is provided on the outer wall of the collet body 16 located above the tip portion 16A, and is engaged with the first engagement portion 15A of the heat-resistant insulating member 15. The third engaging portion 16 </ b> C is provided on the outer wall of the upper end portion of the collet body 16.

A plurality of pilot gas passage holes 16a are formed so as to penetrate a portion of the collet body 16 located between the tip portion 16A and the second engagement portion 16B. The pilot gas supplied to the inner member 11 is supplied to a space formed between the electrode 24 and the center nozzle 27 through the pilot gas passage hole 16a.
The position of the collet body 16 configured as described above is regulated in the heat-resistant insulating member 15.

The torch head 18 is a cylindrical member, and a lower portion thereof is inserted into the heat resistant insulating member 15. The torch head 18 includes a fourth engagement portion 18A, a pilot gas introduction port 18B, and a fifth engagement portion 18C.
The fourth engaging portion 18 </ b> A is provided on the inner wall at the lower end of the torch head 18 and is engaged with the third engaging portion 16 </ b> C of the collet body 16.

The torch head 18 is in contact with the upper end surface of the heat resistant insulator 15. Thereby, the upper part of the torch head 18 is exposed from the heat-resistant insulator 15.
The pilot gas introduction port 18 </ b> B is provided so as to penetrate the upper side wall of the torch head 18. The pilot gas inlet 18B is connected to a pilot gas supply device (not shown). Pilot gas is supplied from the pilot gas supply device to the pilot gas inlet 18B. Further, the pilot gas introduced from the pilot gas introduction port 18 </ b> B is supplied into the torch head 18. The fifth engaging portion 18 </ b> C is provided on the upper inner wall of the torch head 18.

  The torch cap 21 includes a cylindrical member 35 and a cap body 36. The cylindrical member 35 is inserted into the torch head 18, and the lower end thereof is in contact with the upper end of the collet 22. The cylindrical member 35 is a member for adjusting the position of the collet 22 in the collet body 16 with respect to the axial direction A by pushing the collet 22 into the collet body 16.

  The cylindrical member 35 has a sixth engaging portion 35A and a pilot gas passage hole 35B. The sixth engaging portion 35 </ b> A is provided on the upper outer wall of the cylindrical member 35. The sixth engaging portion 35 </ b> A is engaged with the fifth engaging portion 18 </ b> C of the torch head 18. Thereby, the position of the torch cap 21 with respect to the axial direction A of the electrode 24 is regulated.

A plurality of pilot gas passage holes 35B are provided so as to penetrate the side wall of the cylindrical member 35 located in the vicinity of the pilot gas introduction port 18B. Thereby, the pilot gas is introduced into the space in the cylindrical member 35 through the pilot gas passage hole 35 </ b> B, and the pilot gas moves downward of the cylindrical member 35.
The cap body 36 is provided so as to close the upper end which is one open end of the cylindrical member 35.

  The collet 22 has a cylindrical shape and is accommodated in the collet body 16 by the torch cap 21. The collet 22 has a protrusion 22A and a pilot gas passage hole 22a.

The protruding portion 22A is provided on the inner wall of the end portion of the collet 22 located on the distal end portion 16A side. The protruding portion 22 </ b> A protrudes in the direction toward the central axis of the electrode 24 and is in contact with the electrode 24.
When the collet 22 is pressed by the cylindrical member 35 of the torch cap 21 and the lower end of the collet 22 is deformed by the distal end portion 16A, the protruding portion 22A comes into contact with the electrode 24 disposed in the collet 22 so that the axial direction The position of the electrode 24 in A is regulated.

The pilot gas passage hole 22a is provided at a position facing the pilot gas passage hole 16a. The pilot gas that has passed through the pilot gas passage holes 16 a and 22 a is guided to the space between the tip 24 A of the electrode 24 and the center nozzle 27.
The collet 22 configured as described above is disposed on the outer periphery of the electrode 24 so as to expose the tip 24A of the electrode 24, and regulates the position of the electrode 24 with respect to the axial direction A.

  The electrode 24 is a non-consumable electrode extending in the axial direction A. The electrode 24 has a tip 24 </ b> A that is exposed from the collet 22 and at least a part of which is accommodated in the center nozzle 27. The tip portion 24A has a tip 24a that generates an arc by being close to the workpiece to be welded in a state where pilot gas is flowed.

The outer member 12 includes a torch body 26, a center nozzle 27, a center nozzle press 29, an outer nozzle 31, a mesh 32, and a shield gas flow path 33.
The torch body 26 includes a cylindrical space 26A that accommodates the inner member 11 (specifically, the heat-resistant insulating member 15), a cooling water conduit 26B, and a shield gas introduction hole 26a.

  The cooling water conduit 26 </ b> B is formed in a portion of the torch body 26 that is positioned outside the cylindrical space 26 </ b> A. The lower end portion of the cooling water conduit 26 </ b> B is hermetically sealed by the center nozzle 27. The cooling water conduit 26 </ b> B is for flowing cooling water for cooling the center nozzle 27.

The shield gas introduction hole 26 a is provided so as to penetrate a portion of the torch body 26 located between the cooling water conduit 26 </ b> B and the outer nozzle 31. Thereby, the shield gas introduction hole 26a is configured to be able to supply the shield gas to the shield gas flow path 33 disposed below the shield gas introduction hole 26a.
The shield gas introduction hole 26a is connected to a shield gas supply device (not shown). Shield gas is supplied from the shield gas supply device to the shield gas introduction hole 26a.

The center nozzle 27 is provided in the torch body 26 so as to close the lower end of the torch body 26 located on the tip 24 </ b> A side of the electrode 24. The center nozzle 27 includes a cylindrical portion 27A that accommodates a part of the distal end portion 24A of the electrode 24, and a flat distal end surface 27a that faces the workpiece.
Both ends (upper and lower ends) of the cylindrical portion 27A are open ends. The lower end of the cylindrical portion 27A located on the distal end surface 27a side is a portion through which the distal end portion 24A of the electrode 24 passes when the distal end 24a of the electrode 24 protrudes downward from the distal end surface 27a.

  The center nozzle retainer 29 is provided on the side wall of a portion of the torch body 26 located below the shield gas introduction hole 26a. The center nozzle holder 29 attaches the center nozzle 27 to the torch body 26 by pressing the center nozzle 27 against the lower end of the torch body 26.

  The outer nozzle 31 is provided on a side wall of a portion of the torch body 26 located outside the shield gas introduction hole 26a. The outer nozzle 31 is shaped to surround the center nozzle 27 and the center nozzle retainer 29. The front end surface 31 a of the outer nozzle 31 is substantially flush with the front end surface 27 a of the center nozzle 27.

The mesh 32 is disposed between the center nozzle retainer 29 and the outer nozzle 31 located below the shield gas introduction hole 26a.
The shield gas flow path 33 is formed between the center nozzle 27 and the center nozzle retainer 29 and the outer nozzle 31. The shield gas flow path 33 is supplied with the shield gas that has passed through the shield gas introduction hole 26 a and the mesh 32. The shield gas channel 33 guides the shield gas so as to surround the pilot gas supplied to the tip 24 a of the electrode 24.

  The fixing portion 13 is provided on the upper side wall of the torch body 26 via the insulator 41. The fixing portion 13 is fixed to a welding torch support member (not shown) by bolts 43. Thereby, the position of the outer member 12 with respect to the welding torch support member (not shown) is fixed. The fixed part 13 has a pinion support part 44 provided with a pinion 47 which will be described later and constitutes the drive part 14.

The drive unit 14 includes a rack 46 and a pinion 47. The rack 46 is fixed to the upper outer wall of the torch head 18 via an insulator 49. The rack 46 is disposed so as to extend in the axial direction A of the electrode 24.
The pinion 47 engages with the rack 46 and is provided on the pinion support portion 44 in a rotatable state.

  FIG. 2 is a cross-sectional view schematically showing the state of the welding torch when the pinion of the welding torch in the state shown in FIG. 1 is rotated counterclockwise. FIG. 3 is a cross-sectional view schematically showing a state of the welding torch when the pinion of the welding torch in the state shown in FIG. 2 is rotated to the right. 2 and 3, the same components as those of the welding torch 10 shown in FIG.

  As shown in FIG. 2, when the pinion 47 is rotated counterclockwise from the state shown in FIG. 1, the rack 46 moves downward with respect to the pinion 47 from the state shown in FIG. 1, and thus the inner member 11 to which the rack 46 is fixed. Also move downwards. As a result, the electrode 24 is also moved downward from the state shown in FIG.

Further, when the pinion 47 is rotated clockwise from the state shown in FIG. 3, the rack 46 moves upward with respect to the pinion 47 from the state shown in FIG. 2, so that the inner member 11 to which the rack 46 is fixed also moves upward. . As a result, the electrode 24 also moves upward from the state shown in FIG. 2, so that the tip 24 a of the electrode 24 is accommodated in the center nozzle 27 as shown in FIG. 3.
The pinion 47 may be manually rotated or automatically rotated.

  When the workpiece 51 is plasma welded using the welding torch 10 having the above-described configuration, as shown in FIG. 2, the tip 24a of the electrode 24 is projected from the tip surface 27a of the center nozzle 27 and the pilot gas is allowed to flow. Thus, an arc is generated between the tip 24a of the electrode 24 and the work piece 51, and thereafter, as shown in FIG. 3, the tip 24a of the electrode 24 is accommodated in the center nozzle 27 and a shielding gas is allowed to flow. The workpiece 51 is welded.

  According to the welding torch of the present embodiment, the electrode 24 including the tip 24A (including the tip 24a) to which the pilot gas is supplied and the tip 24A of the electrode 24 are disposed on the outer periphery of the electrode 24 so as to be exposed. In addition, the inner member 11 having the collet 22 that regulates the position of the electrode 24 with respect to the axial direction A of the electrode 24 and the center nozzle 27 that houses at least a part of the tip 24A of the electrode 24 are separated from the center nozzle 27. The outer nozzle 31 disposed outside the center nozzle 27, and the shield gas flow path 33 that is formed between the center nozzle 27 and the outer nozzle 31 and through which the shield gas flows toward the tip end surface 27 a of the center nozzle 27. And an outer member 12 disposed so as to surround a part of the outer peripheral portion of the inner member 11. And the drive unit 14 that relatively moves the inner member 11 and the outer member 12 with respect to the axial direction A of the electrode 24, thereby causing the tip 24 a of the electrode 24 to protrude from the tip surface 27 a of the center nozzle 27. By flowing the pilot gas, it becomes possible to generate an arc (pilot arc) between the tip 24a of the electrode 24 and the workpiece 51, and after generating the arc, the tip 24a of the electrode 24 is The workpiece 51 can be plasma welded by being accommodated in the center nozzle 27 and flowing a shielding gas.

  This eliminates the need for an expensive pilot arc generator (apparatus for generating a pilot arc) that was necessary when plasma welding a workpiece to be welded using a conventional plasma welding torch. The cost when performing the process can be reduced.

  Moreover, plasma welding is easily performed by attaching a welding torch 10 including an inner member 11, an outer member 12, and a drive unit 14 to a TIG welding machine having a higher penetration rate than a plasma welding machine. It can be carried out.

Moreover, the effect similar to the welding torch 10 of this Embodiment can be acquired by plasma-welding the to-be-welded object 51 using the welding torch 10 set as the said structure.
Furthermore, in conventional TIG welding, helium (other gas having a high potential gradient) was used as a shielding gas in order to obtain deep penetration, but in the present invention, even when argon alone is used as the shielding gas. Compared with conventional TIG welding using helium as a shielding gas, deep penetration equal to or higher than that can be obtained.

  In the present embodiment, as an example, the case where the outer member 12 is fixed and the inner member 11 is moved in the axial direction A of the electrode 24 with respect to the outer member 12 has been described as an example. The electrode 24 may be moved in the axial direction A by fixing and making the outer member 12 movable with respect to the inner member 11.

  Furthermore, in the present embodiment, the case where the electrode 24 is moved using the rack and pinion made up of the rack 46 and the pinion 47 as an example of the driving unit 14 has been described as an example. It is not limited to. For example, a mechanism such as a mechanical type, an electromagnetic type, a pneumatic type, a hydraulic type, or a spring type may be provided, and the electrode 24 may be moved by the mechanism.

  4 and 5 are diagrams for explaining another application example of the welding torch according to the present embodiment. 4 and 5, the same components as those of the structure shown in FIG.

Here, with reference to FIG.4 and FIG.5, the other application example of the welding torch 10 of this Embodiment is demonstrated.
As shown in FIG. 4, TIG / MIG welding can be performed by projecting the tip 24 a of the electrode 24 from the tip surface 27 a of the center nozzle 27 and combining with GMA welding (gas metal arc welding).
Moreover, as shown in FIG. 5, plasma MIG welding can be performed by accommodating the tip 24a of the electrode 24 in the center nozzle 27 and combining it with GMA welding.

  Further, as shown in FIG. 2, the electrode 24 is protruded from the front end surface 27a of the center nozzle 27, and the same kind of gas or different gas is allowed to flow as a shield gas through the pilot gas flow path and the shield gas flow path. It is also possible to use it as a torch for TIG welding using a machine.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and within the scope of the present invention described in the claims, Various modifications and changes are possible.

(Experimental example 1)
FIG. 6 is a diagram for explaining the positional relationship between the front end surface of the center nozzle and the front end of the electrode when performing welding in the first embodiment. FIG. 6 shows only the electrode 24 and the center nozzle 27 among the components of the welding torch 10 shown in FIG.

  1, the tip 24a of the electrode 24 is projected 3 mm from the tip surface 27a of the center nozzle 27, and a thin plate (for example, 5 mm) that is the tip 24a of the electrode 24 and the workpiece 51 is used. The distance between the tip 24a of the electrode 24 and the workpiece 51 is generated by the high-frequency start method. Thereafter, the electrode 24 is moved 6 mm upward, and the tip 24a of the electrode 24 is moved. The main welding was performed by fixing the center nozzle 27 at a position 3 mm deep from the front end surface 27a. Further, the distance between the front end surface 27a of the center nozzle 27 and the upper surface 51a of the workpiece 51 was set to 5 mm.

  At this time, using a TIG welder, the current was 200 A, the welding speed was 30 cm / min, the pilot gas was 100% argon (flow rate was 3 L / min), the shield gas was 100% argon (flow rate was 15 L / min), the center A SUS304 plate (workpiece 51) with a nozzle thickness of 5 mm and an electrode 24 outer diameter of 4 mm and a plate thickness of 5 mm was welded. FIG. 8 shows a cross-sectional photograph of the workpiece 51 after welding in Example 1 and the penetration depth.

(Experimental example 2)
FIG. 7 is a diagram for explaining the positional relationship between the front end surface of the center nozzle and the front end of the electrode when performing welding in the second embodiment. FIG. 7 shows only the electrode 24 and the center nozzle 27 among the components of the welding torch 10 shown in FIG.

  1, the tip 24a of the electrode 24 protrudes 10 mm from the tip surface 27a of the center nozzle 27, and the tip 24a of the electrode 24 and the work piece 51 (specifically, the thickness is increased). (For example, a thickness greater than 5 mm) and a plate material having a groove) is set to 3 mm, an arc is generated between the tip 24a of the electrode 24 and the workpiece 51 by a high frequency start method, and then The electrode 24 was moved upward 13 mm, and the tip 24 a of the electrode 24 was fixed at a position 3 mm deep from the tip surface 27 a of the center nozzle 27 to perform the main welding. Further, the distance between the front end surface 27a of the center nozzle 27 and the upper surface 51a of the workpiece 51 was set to 5 mm.

  At this time, using a TIG welder, the current was 200 A, the welding speed was 30 cm / min, the pilot gas was 100% argon (flow rate was 3 L / min), the shield gas was 100% argon (flow rate was 15 L / min), the center The SUS304 plate (workpiece 51) having a plate thickness of 12 mm was welded with the inner diameter of the nozzle 27 being 5 mm and the outer diameter of the electrode 24 being 4 mm.

(Comparative example)
Using a conventional TIG welding torch, main welding of a workpiece (specifically, a thin plate) was performed. At this time, using a TIG welder, welding of a SUS304 plate (workpiece 51) with a current of 200A, a welding speed of 30 cm / min, 100% argon (flow rate of 10 L / min) and a plate thickness of 5 mm. Went.
FIG. 8 shows a cross-sectional photograph and a penetration depth of the work piece after welding in the comparative example.

(About the penetration depth of Example 1 and Comparative Example)
Referring to FIG. 8, when 100% argon gas is used as the welding gas and welding is performed with the same current, Example 1 has a deeper penetration depth of about 1.4 mm than the comparative example. It could be confirmed.

  That is, while using a TIG welder and using 100% argon as a shielding gas, it was confirmed that the penetration depth could be deeper than conventional TIG welding (heat input could be increased).

  The present invention can be applied to a welding torch and a plasma welding method capable of reducing the cost required for plasma welding and easily performing plasma welding.

  DESCRIPTION OF SYMBOLS 10 ... Welding torch, 11 ... Inner member, 12 ... Outer member, 13 ... Fixed part, 14 ... Drive part, 15 ... Heat-resistant insulating member, 15A ... 1st engaging part, 16 ... Collet body, 16A, 24A ... Tip , 16a, 22a, 35B ... pilot gas passage hole, 16B ... second engagement portion, 16C ... third engagement portion, 18 ... torch head, 18A ... fourth engagement portion, 18B ... pilot gas Inlet, 18C: Fifth engaging portion, 21: Torch cap, 22: Collet, 22A ... Projection, 24 ... Electrode, 24a ... Tip, 26 ... Torch body, 26A ... Cylindrical space, 26B ... For cooling water Pipe line, 26a ... shield gas introduction hole, 27 ... center nozzle, 27A ... cylindrical part, 27a, 31a ... tip surface, 29 ... center nozzle press, 31 ... outer nozzle, 32 ... mesh, 33 ... sea Degas channel, 35 ... cylindrical member, 35A ... sixth engaging part, 36 ... cap body, 41, 49 ... insulator, 43 ... bolt, 44 ... pinion support part, 46 ... rack, 47 ... pinion, 51 ... Workpiece, 51a ... Upper surface, A ... Axial direction

Claims (6)

An inner member having an electrode including a tip portion to which pilot gas is supplied, and a collet that is disposed on the outer periphery of the electrode so as to expose the tip portion of the electrode and regulates the position of the electrode with respect to the axial direction of the electrode When,
A center nozzle that accommodates at least a part of the tip of the electrode, an outer nozzle that is disposed outside the center nozzle so as to be separated from the center nozzle, and formed between the center nozzle and the outer nozzle And an outer member disposed so as to surround a part of the outer peripheral portion of the inner member, having a shield gas flow path for guiding a shield gas toward the tip of the center nozzle,
A drive unit that moves the inner member and the outer member relative to the axial direction of the electrode;
A welding torch comprising:   The tip of the electrode protrudes from the tip surface of the center nozzle or is accommodated in the center nozzle as the inner member and the outer member move relative to the axial direction of the electrode. The welding torch according to claim 1, wherein: The drive unit is provided on a portion of the outer peripheral portion of the inner member that is exposed from the outer member, and extends in the axial direction of the electrode;
A pinion that engages with the rack and rotates to move the inner member in the axial direction of the electrode;
The welding torch according to claim 1 or 2, characterized by comprising:   The welding torch according to claim 3, wherein the outer member is fixed to a welding torch support member.   The welding torch according to any one of claims 1 to 4, wherein the electrode is a non-consumable electrode. A plasma welding method using the welding torch according to any one of claims 1 to 5,
Protruding the tip of the electrode from the tip surface of the center nozzle and flowing the pilot gas to generate an arc between the tip of the electrode and the workpiece to be welded;
After the arc is generated, the tip of the electrode is accommodated in the center nozzle, and a welding gas is flowed to weld the workpieces;
A plasma welding method comprising: