JP2013086176A - Plasma cutting torch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma cutting torch capable of suppressing temperature increase by improving cooling performance.SOLUTION: The plasma cutting torch is composed by mounting an electrode having a negative pole material on the edge on the edge part of a torch body tool inserting an orifice gas introduction pipe in the center, by adjacently providing a chip shrinking a plasma flow and an orifice having heat resistance on the outer peripheral part of the electrode on the same axis as the electrode, and by allowing the orifice gas introduced in the orifice gas introduction pipe to pass on the electrode and the inner and outer faces of the chip through the orifice through a ring-like route between the inner face of the torch body tool and the outer faces of the orifice gas introduction pipe. The plasma cutting torch includes an insertion cylinder in the electrode, and a spiral groove on the outer peripheral part of the insertion cylinder. The insertion cylinder is provided in the inside of the electrode so that the end of the insertion cylinder is brought into contact with the bottom part of the electrode or the negative pole material. In addition, the plasma cutting torch includes the spiral groove on the outer peripheral part of the orifice gas introduction pipe, and the orifice gas introduction pipe is provided in the torch body tool so that the outer peripheral part of the orifice gas introduction pipe and the inner face of the torch body tool are brought into contact with each other.

Description

  The present invention relates to a plasma cutting torch using a working gas.

  In order to cool an electrode of a plasma cutting torch, conventionally, a fin-shaped groove is provided around the electrode to cool the electrode (see, for example, Patent Document 1 and Patent Document 2). However, the cathode material attached to the electrode is provided at a position away from the fin. Therefore, the cooling effect on the cathode material is not sufficient, the cutting operation cannot be performed for a long time (for example, about 1 hour), and the life of the electrode is short.

  In recent years, there has been known a technique in which a working gas is blown into an electrode and cooled to dramatically increase the life of the electrode (for example, about 3 to 4 hours) (for example, see Patent Document 3). However, in the conventional plasma cutting torch, the cooling of the tip portion (around the electrode and the chip) is regarded as important, and the entire torch body is not cooled. Therefore, a temperature difference has occurred between the tip of the plasma cutting torch and the inlet of the working gas to the torch main body. Due to this temperature difference, a gap is generated between the metal part and the resin part constituting the torch body part. Further, a gap is generated on the contact surface between the ceramic portion and the resin portion due to the difference in thermal expansion between the ceramic portion and the resin portion. And it became easy for a high frequency current to flow through this gap, and insulation could not be secured.

  FIG. 9 shows a schematic configuration of a conventional plasma arc cutting apparatus using a working gas. In FIG. 9, the compressor 2 that compresses the working gas is connected to the regulator 3, and the secondary pressure of the working gas is adjusted to a constant value by the regulator 3. Further, the regulator 3 is connected to the inside of the cutting power supply 4 and is connected to a gas valve (not shown) that is turned on / off in response to an instruction to start or stop the plasma arc provided in the cutting power supply 4. This gas valve is connected to a cooling cable 8 that sends working gas to the torch tip 1. The cutting power supply 4 is provided with a grounding cable 6 for connection to the base material 5. Further, the cutting power supply 4 is provided with a pilot cable 9 and a torch switch cable 10 for outputting a high-frequency voltage for improving the arc start.

  On the other hand, the plasma cutting torch 7 is connected to the cutting power supply 4 by a cooling cable 8 with a built-in electric wire, a pilot cable 9 and a torch switch cable 10. Note that the pilot cable 9 is not used in the contact cutting in which the chip is in contact with the base material 5 for cutting. The working gas is supplied from the cutting power supply 4 to the torch tip 1 of the plasma cutting torch 7 via the cooling cable 8.

  The plasma arc cutting device 11 is configured as described above.

  Next, the structure of a conventional plasma cutting torch will be described with reference to FIGS. FIG. 10 is a cross-sectional view of the plasma cutting torch 7. 11 is a cross-sectional view taken along line BB in FIG.

  In FIG. 10, the working gas 50 is led from a mounting nut 51 to which a cooling cable (not shown) is attached, through a pipe 52, to a cavity 55 in a head fitting 53, and sent to the working gas introduction pipe 12. The working gas introduction pipe 12 is fixed to the body fitting 13 by an introduction pipe fixing fitting 54 made of copper or a copper alloy. The working gas introduction pipe 12 is disposed inside the main body fitting 13. An electrode 14 made of copper or a copper alloy is screwed to the front end of the main body 13. An insertion cylinder 16A provided with a plurality of small holes is inserted into the electrode 14.

  The tip of the electrode 14 has an electron emission surface in which a cathode material 15 such as zirconium or hafnium is embedded. A chip 16 made of copper or a copper alloy is provided on the outer peripheral portion of the electrode 14 so as to be coaxial and supply a plasma flow to the base material 5 by constricting the plasma arc. Further, an orifice 17 that is adjacent to the tip 16 and electrically insulates the electrode 14 and the tip 16 is provided. The orifice 17 is provided with a small hole 17 a communicating with the small hole 13 a provided in the main body 13 and a small hole 17 b communicating with the inner surface side of the chip 16. A nozzle fitting 18 is provided on the outer periphery of the tip 16 and the orifice 17. Then, the nozzle 16 and the tip 16 are screwed together so that the tip 16 and the orifice 17 are fixed to the main body 13.

  In addition, a nozzle 19 that prevents the conductive portion from being exposed to the outside is screwed and fixed to the outer peripheral portion of the nozzle fitting 18. The tip opening of the nozzle 19 communicates with the small hole 17 a of the orifice 17 through a small hole 18 a provided in the nozzle fitting 18. Accordingly, the working gas 50 that has flowed into the small hole 17a of the orifice 17 from the small hole 13a of the main body fitting 13 is diverted to the inner surface and the outer surface of the tip 16 by the small hole 17b of the orifice 17 and the small hole 18a of the nozzle fitting 18. .

  The mold part 20 is an insulating material provided adjacent to the nozzle 19 so as to cover the nozzle fitting 18 and prevents the formation of the torch body part and the external exposure of the conductive part of the torch body part.

  Next, the flow of the working gas 50 will be described. As indicated by arrows in FIG. 10, the working gas 50 passes through the pipe 52 from the inside of the mounting nut 51 connected to the cooling cable (not shown) containing the electric wire, and is a cavity provided in the head fitting 53. It flows to 55. Then, the working gas is introduced from the cavity 55 to the working gas introduction pipe 12 and is further introduced into the inner surface of the electrode 14 and the inner peripheral surface of the body fitting 13 through the small hole from the opening of the insertion tube 16A opened coaxially with the electrode 14. It passes through an annular path 21 between the outer peripheral surface of the tube 12. Furthermore, the small hole 13 a provided in the main body fitting 13 passes through the small hole 17 a of the orifice 17 and passes through the path between the outer peripheral surface of the orifice 17 and the inner peripheral surface of the nozzle fitting 18. This route is divided into a route passing through the small hole 17 b of the orifice 17 and a route passing through the small hole 18 a of the nozzle fitting 18. As one path, the working gas 50 passes through a path between the outer peripheral surface of the electrode 14 and the inner peripheral surface of the tip 16 from the small hole 17 b of the orifice 17 and is ejected to the outside from the tip opening of the tip 16. Further, as the other path, the working gas 50 passes from the small hole 18 a of the nozzle fitting 18 through the path between the outer peripheral surface of the tip 16 and the inner peripheral surface of the nozzle 19, and from the front end opening of the nozzle 19. Is erupted.

  In this way, the working gas 50 passes through the inner and outer peripheral surfaces of the electrode 14 and the tip 16, cools the electrode 14 and the tip 16, and contracts the plasma arc.

Japanese Utility Model Publication Sho 62-082184 Japanese Utility Model Publication No. 63-196374 JP-A-3-114677

  In the conventional plasma cutting torch 7, as shown in FIG. 10, the working gas 50 passes through the pipe 52 from the attachment nut 51 to which the cooling cable 8 is attached, and enters the cavity 55 provided in the head fitting 53. It is guided and sent to the working gas introduction pipe 12. However, the working gas 50 passes in a short time, and the metal fittings such as the main body fitting 13, the head fitting 53, the introduction pipe fixing fitting 54, and the mold part 20 cannot be sufficiently cooled. Then, when a heat cycle such as repeated cutting or cutting that causes abnormal work to be blown up is performed, the temperature of the metal part increases. In this case, a micro gap is generated on the joint surface due to the difference in expansion coefficient between the resin part and the metal part, the resin part and the ceramic part, such as the mold part 20 and the main body fitting 13 and the mold part 20 and the orifice 17. And when temperature rise is high, the swelling and melting | fusing of the resin part were derived, and insulation might deteriorate.

  It should be noted that a copper alloy cylindrical insertion cylinder 16A having a small hole was press-fitted into the distal end of the working gas introduction pipe 12 inserted in the center of the body fitting 13 (see, for example, Patent Document 3). Thereby, the lifetime of the electrode could be extended. However, this was insufficient, and there was a problem with the life of the electrodes.

  This is because the working gas 50 passes through the center of the working gas introduction pipe 12 and then flows on the inner and outer surfaces of the chip 16 through the annular path 21. Since the fin-shaped slit parallel to the axial direction is provided, the working gas 50 passes in a short time, has a small cooling effect, and cannot generate a tight plasma arc.

  In order to solve the above-mentioned problems, the plasma cutting torch of the present invention has an electrode having a cathode material attached to the tip of a torch body fitting in which a working gas introduction tube is inserted in the center, and is coaxial with the electrode. A tip for constricting the plasma flow and an orifice made of an insulating material having heat resistance are provided adjacent to the outer periphery of the electrode, and the working gas introduced into the working gas introduction pipe is connected to the inner surfaces of the electrode and the torch main body metal fitting. A plasma cutting torch configured to pass through an annular path between the working gas introduction pipe and the outer surface of the working gas introduction pipe to the inner and outer surfaces of the tip through the orifice, and from the copper or copper alloy in the electrode The insertion cylinder is provided, a spiral groove is provided in the outer periphery of the insertion cylinder, and the insertion cylinder is press-fitted into the electrode so that the end of the insertion cylinder is in contact with the bottom of the electrode or the cathode material. It is those provided Te.

  In addition to the above, the plasma cutting torch of the present invention has three or more spiral grooves provided in the insertion cylinder.

  In addition, the plasma cutting torch of the present invention has an electrode having a cathode material attached to the tip of the torch body fitting with the working gas introduction tube inserted in the center, and coaxially with the electrode on the outer periphery of the electrode. A tip for constricting the plasma flow and an orifice made of an insulating material having heat resistance are provided adjacent to each other, and the working gas introduced into the working gas introduction pipe is connected to the inner surface of the electrode and the torch body fitting and the working gas introduction pipe. A plasma cutting torch configured to pass through an annular path between the tip and the outer surface of the tip through the orifice to the inner and outer surfaces of the tip, wherein a spiral groove is provided on the outer periphery of the working gas introduction tube The working gas introduction pipe is provided in the torch body fitting so that the outer peripheral portion of the working gas introduction pipe and the inner surface of the torch body fitting are in contact with each other.

  In addition to the above, the plasma cutting torch of the present invention has two or more spiral grooves provided in the working gas introduction tube.

  In addition, the plasma cutting torch of the present invention has an electrode having a cathode material attached to the tip of the torch body fitting with the working gas introduction tube inserted in the center, and coaxially with the electrode on the outer periphery of the electrode. A tip for constricting the plasma flow and an orifice made of an insulating material having heat resistance are provided adjacent to each other, and the working gas introduced into the working gas introduction pipe is connected to the inner surface of the electrode and the torch body fitting and the working gas introduction pipe. A plasma cutting torch configured to pass through an annular path between the tip and the outer surface of the tip to the inner and outer surfaces of the tip, and at the inlet portion of the working gas introduction pipe, from copper or copper alloy An introduction pipe fixing bracket having a hollow cylindrical central portion is provided, and the introduction pipe fixing bracket includes a plurality of holes communicating from the outer peripheral portion of the introduction pipe fixing bracket to the center portion, and the introduction pipe fixing metal Is provided with a convex portion on the outer peripheral portion, and the introduction pipe fixing bracket is provided between a pipe for guiding the working gas and an inlet portion of the working gas introduction pipe. A copper alloy head fitting is provided.

  In addition to the above, in the plasma cutting torch of the present invention, the working gas path axial section of the hole provided in the introduction pipe fixing bracket is larger than the working gas axis section of the working gas introduction pipe.

  In addition to the above, in the plasma cutting torch according to the present invention, the convex portion provided on the outer peripheral portion of the introduction pipe fixing metal fitting has a fin shape or a donut shape.

  In the plasma cutting torch according to the present invention, an insertion tube made of copper or a copper alloy is provided in the electrode, grooves at equal intervals are provided at the end of the insertion tube, and the end of the insertion tube is the bottom of the electrode. Or it is set as the structure which touches a cathode material. Thereby, the heat capacity of the insertion cylinder in the electrode is increased, the electrode and the cathode material can be cooled, and the electrode life can be extended.

  Further, the plasma cutting torch of the present invention has a configuration in which spiral grooves of equal intervals are provided on the outer peripheral portion of the working gas introduction tube. The working gas introduction pipe is arranged so that the spiral outer peripheral portion of the working gas introduction pipe and the inner surface of the torch body fitting are in contact with each other. With such a configuration, it is possible to realize a plasma cutting torch that suppresses the temperature rise of the working gas and generates a tight plasma arc that supplies the cooled working gas to the tip, and eliminates the series arc and reduces the life of the tip. Can be lengthened.

  In the plasma cutting torch of the present invention, the working gas is flowed from the cavity formed by the head fitting to the working gas introduction pipe through the introduction pipe fixing fitting, thereby improving the cooling efficiency. Thereby, even if it cuts repeatedly and the cutting operation | work which produces abnormal blow-up is performed, the temperature rise of a mold part or a metal fitting part can be suppressed.

Sectional drawing of the principal part of the plasma cutting torch in Embodiment 1 of this invention Sectional drawing of the principal part of the torch main-body part of the plasma cutting torch in Embodiment 1 of this invention The figure which shows the AA cross section in FIG. 1 and FIG. 2 of the plasma cutting torch in this Embodiment 1 of this invention The figure which shows an example of the head metal fitting in Embodiment 1 of this invention. (A) The figure which shows an example of the insertion tube in Embodiment 1 of this invention (b) The figure which shows an example of the insertion tube in Embodiment 1 of this invention (c) An example of the electrode in Embodiment 1 of this invention Figure showing The figure which shows an example of the working gas introduction pipe | tube in Embodiment 1 of this invention The figure which shows the lifetime comparison of the electrode of the conventional plasma cutting torch at the time of performing contact cutting, and the plasma cutting torch of this invention The figure which shows the limiting current with respect to the tip hole diameter of the conventional cutting torch and the cutting torch of the present invention A perspective view of a conventional general plasma arc cutting device Cross section of conventional plasma cutting torch The figure which shows the BB arrow cross section of FIG. 10 in the conventional plasma cutting torch. Arrow view of conventional working gas introduction pipe The perspective view which shows the electrode and insertion cylinder of the torch front-end | tip part of the conventional plasma cutting torch

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a main part of the plasma cutting torch in the first embodiment. FIG. 2 is a cross-sectional view of the main part of the torch body portion of the plasma cutting torch according to the first embodiment. FIG. 3 is a view showing the AA cross section in FIG. 1 and FIG. 2 of the plasma cutting torch in the first embodiment. FIG. 4 is a diagram showing an example of the head fitting in the first embodiment. FIG. 5 is a diagram illustrating an example of an insertion tube and an example of an electrode according to the first embodiment. FIG. 6 is a diagram illustrating an example of the working gas introduction pipe in the first embodiment. FIG. 7 is a diagram showing a life comparison of electrodes between a conventional plasma cutting torch and a plasma cutting torch according to the present invention when contact cutting is performed. FIG. 8 is a diagram showing the limit current with respect to the tip hole diameter of the conventional cutting torch and the cutting torch of the present invention.

  Note that portions similar to those described in the sections “Background Art” and “Problems to be Solved by the Invention” are denoted by the same reference numerals, and detailed description thereof is omitted. The plasma cutting torch according to the first embodiment mainly has three structural features, and will be described below in order.

  First, the characteristics of the first configuration of the plasma cutting torch according to the first embodiment will be described.

  FIG. 1 is a cross-sectional view of a plasma cutting torch. In FIG. 1, a portion excluding the mounting nut 51 and the pipe 52 is referred to as a torch body portion. FIG. 2 is a cross-sectional view of the torch body.

  1 and 2, the plasma cutting torch according to the first embodiment is characterized in that an introduction pipe fixing bracket 54 is provided at the gas inlet portion of the working gas introduction pipe 12, and the shape of the introduction pipe fixing bracket 54 is characteristic. One. An example of the appearance of the introduction pipe fixing metal 54 is shown in FIG. The introduction pipe fixing fitting 54 is made of copper or a copper alloy, has a cylindrical shape, and has a hollow center part. In addition, the introduction pipe fixing metal 54 is provided with a plurality of holes in the side wall communicating from the outer peripheral portion to the central portion, and further, a fin-like or donut-like convex portion is provided on the outer peripheral portion.

  The introduction pipe fixing metal 54 is provided between the pipe 52 that guides the working gas 50 and the inlet portion of the working gas introduction pipe 12. Then, a copper or copper alloy head fitting 53 is provided outside the introduction pipe fixing fitting 54 so that a cavity is formed on the outer periphery of the introduction pipe fixing fitting 54. The cross section of the working gas path of the introduction pipe fixing metal 54 orthogonal to the axis of the introduction pipe fixing metal 54 is larger than the cross section of the gas path axis of the working gas introduction pipe 12.

  Next, the flow of the working gas 50 will be described.

  In FIG. 1, the cooling cable 8 shown in FIG. 9 used for the description of “background art” is attached to the attachment nut 51. The working gas 50 is guided through the pipe 52 to the cavity 55 inside the head fitting 53, passes through the hole in the side wall of the introduction pipe fixing fitting 54 from the cavity 55, passes through the inside of the introduction pipe fixing fitting 54, and introduces the working gas. Guided to tube 12.

  As described above, when the working gas 50 passes through the introduction pipe fixing fitting 54 from the cavity 55, the head fitting 53 is deprived of heat to cool the head fitting 53.

  The introduction pipe fixing metal 54 is provided with a fin-shaped or donut-shaped convex portion on the outer peripheral portion, and the contact area with the working gas 50 is large. As a result, the heat dissipation effect is further increased, and the effect that the temperature of the head fitting 53 does not rise is achieved.

  As described above, in the plasma cutting torch of the first embodiment, the cooling efficiency is improved by flowing the working gas 50 from the cavity 55 formed by the head fitting 53 to the working gas introduction pipe 12 via the introduction pipe fixing fitting 54. It has improved. Thereby, even if it performs the cutting operation | work which repeats a cutting | disconnection and abnormal blowing up, the temperature rise of the mold part 20 or a metal fitting part can be restrained low, for example to 30 degrees or less.

  Therefore, it is possible to reduce strain due to expansion of the resin part and metal part, the resin part and ceramic part, such as the mold part 20 and the main body metal fitting 13, the mold part 20 and the orifice 17, and the occurrence of micro gaps in the joint surface and abnormal use. Resin melting and swelling can be eliminated, and a safe plasma cutting torch can be realized.

  Next, features of the second configuration of the plasma cutting torch of the first embodiment will be described.

  In FIG. 2, the insertion tube 16 </ b> B made of copper or a copper alloy is press-fitted and provided inside the electrode 14. The insertion cylinder 16B is provided with three or more grooves at equal intervals. More specifically, a groove is provided spirally in the circumferential direction of the insertion cylinder 16B. The insertion tube 16B is provided in the electrode 14 so that the end thereof is in contact with the bottom of the electrode 14 or the cathode material 15.

  Here, the electrode 14, the cathode material 15, and the insertion cylinder 16B are shown in FIG. FIG. 5C shows a state in which the cathode material 15 is attached to the electrode 14. And the insertion cylinder 16B shown to Fig.5 (a) is provided in the inside of the electrode 14 of FIG.5 (c). FIG. 5B is a reference diagram showing a state in which the insertion tube 16B of FIG.

  By providing the insertion tube 16B in the electrode 14 as described above, heat transfer of the insertion tube 16B in the electrode 14 is facilitated, the heat capacity is increased, and the electrode 14 and the cathode material 15 can be forcibly cooled.

  The working gas 50 passes through the center of the insertion tube 16B and is discharged to the inner end of the cathode material 15, and the cathode material 15 is heated to a higher temperature than the electrode 14. The plasma arc is generated in a concentrated manner at the center of the electrode 14. For this reason, the arc becomes straight and the abnormal cutting of the oblique cutting is eliminated.

  As described above, in the plasma cutting torch of the first embodiment, the insertion tube 16B made of copper or a copper alloy is provided in the electrode 14, and three or more grooves at equal intervals are provided at the end of the insertion tube 16B. The insertion tube 16B is press-fitted into the electrode 14 so that the end of the insertion tube 16B is in contact with the bottom of the electrode 14 or the cathode material 15. Therefore, the heat capacity of the insertion tube 16B in the electrode 14 is increased, and the electrode 14 and the cathode material 15 are forcibly cooled, and the electrode life can be further extended by about 20%.

  Next, features of the third configuration of the plasma cutting torch of the first embodiment will be described.

  As shown in FIG. 6, the working gas introduction pipe 12 has a configuration in which two or more spiral grooves of equal intervals are provided on the outer peripheral portion. The working gas introduction pipe 12 is disposed so that the helical outer peripheral portion of the working gas introduction pipe 12 and the inner surface of the main body fitting 13 are in contact with each other. By adopting such a configuration, it is possible to realize a plasma cutting torch that suppresses the temperature rise of the working gas 50 and generates a tight plasma arc that supplies the cooled working gas 50 to the chip 16. The series arc is eliminated and the life of the chip 16 is extended.

  As described above, according to the plasma cutting torch of the first embodiment having the three structural features, the mounting nut which is the cable joint portion from the tip portion (around the electrode 14 and the tip 16) of the torch main body portion. The cooling effect up to 51 can be enhanced, and the electrode life can be extended as shown in FIG. FIG. 7 shows the wear length of the electrode with respect to the cutting time, and the lower line is the result of the first embodiment. FIG. 7 shows that the plasma cutting torch of the first embodiment has a shorter consumption length than the conventional plasma cutting torch at the same cutting time. Test conditions were SPHt 12 mm for the base material, 0 mm between the base materials (contact cutting), current 60 A, air pressure 5 kgf / cm 2, and cutting with a cutting length of 25 cm.

  Further, according to the plasma cutting torch of the first embodiment, even if abnormal cutting is performed with a thick plate exceeding the cutting capability, there is no sudden temperature rise, and the part of the mold part 20 is not damaged. Was secured. The limit value of the withstand voltage was 10 kV / mm. Further, defects such as melting and swelling of the mold part 20 were not observed.

  FIG. 8 shows a series arc generation limit graph showing that a large amount of current can flow for the same hole diameter of the tip 16. The left line in FIG. 8 shows the result of the plasma cutting torch of the first embodiment. As shown in FIG. 8, according to the first embodiment, a larger amount of current can be passed in the same hole diameter of the chip 16 than in the conventional plasma cutting torch, and a high-performance plasma cutting torch can be realized.

  In addition, by increasing the cooling efficiency, it is possible to make maximum use of the expensive cathode material 15 Hf (hafnium), to provide an eco-friendly plasma cutting torch that ensures long-term safety. The effect that can be done is great.

  Also in manual cutting and automatic cutting, it is possible to supply a plasma cutting torch that can stabilize the cutting quality for a long period of time, and the effect is great.

  The plasma cutting torch of the present invention can suppress an increase in temperature during use, and is industrially useful as a plasma cutting torch that performs processing using a working gas.

DESCRIPTION OF SYMBOLS 1 Torch front-end | tip part 2 Compressor 3 Regulator 4 Power supply for cutting 5 Base material 6 Grounding cable 7 Plasma cutting torch 8 Cooling cable 9 Pilot cable 10 Torch switch cable 11 Plasma arc cutting device 12 Working gas introduction pipe 13 Body metal fitting 14 Electrode 15 Cathode material 16 Tip 16A Insertion cylinder 16B Insertion cylinder 17 Orifice 13a, 17a, 17b, 18a Small hole 18 Nozzle fitting 19 Nozzle 20 Mold part 21 Annular path 50 Working gas 51 Mounting nut 52 Pipe 53 Head fitting 54 Introducing pipe fixing fitting 55 Cavity

Claims (7)

An electrode having a cathode material at the tip is attached to the tip of the torch body fitting with the working gas introduction tube inserted in the center, and a tip for constricting the plasma flow and heat resistance are coaxial with the electrode and on the outer periphery of the electrode. An orifice made of an insulating material is provided adjacently, and the working gas introduced into the working gas introduction pipe passes through an annular path between the electrode and the inner surface of the torch body fitting and the outer surface of the working gas introduction pipe. A plasma cutting torch configured to pass through the orifice to the inner and outer surfaces of the chip,
An insertion cylinder made of copper or a copper alloy is provided in the electrode, a spiral groove is provided in an outer peripheral portion of the insertion cylinder, and the electrode is arranged such that an end of the insertion cylinder is in contact with the bottom of the electrode or the cathode material A plasma cutting torch provided by press-fitting the insertion tube inside. The plasma cutting torch according to claim 1, wherein the number of spiral grooves provided in the insertion tube is three or more. An electrode having a cathode material at the tip is attached to the tip of the torch body fitting with the working gas introduction tube inserted in the center, and a tip for constricting the plasma flow and heat resistance are coaxial with the electrode and on the outer periphery of the electrode. An orifice made of an insulating material is provided adjacently, and the working gas introduced into the working gas introduction pipe passes through an annular path between the electrode and the inner surface of the torch body fitting and the outer surface of the working gas introduction pipe. A plasma cutting torch configured to pass through the orifice to the inner and outer surfaces of the chip,
A spiral groove is provided in the outer peripheral part of the working gas introduction pipe, and the working gas introduction pipe is provided in the torch main body fitting so that the outer peripheral part of the working gas introduction pipe and the inner surface of the torch main body fitting are in contact with each other. Plasma cutting torch. The plasma cutting torch according to claim 3, wherein the number of spiral grooves provided in the working gas introduction pipe is two or more. An electrode having a cathode material at the tip is attached to the tip of the torch body fitting with the working gas introduction tube inserted in the center, and a tip for constricting the plasma flow and heat resistance are coaxial with the electrode and on the outer periphery of the electrode. An orifice made of an insulating material is provided adjacently, and the working gas introduced into the working gas introduction pipe passes through an annular path between the electrode and the inner surface of the torch body fitting and the outer surface of the working gas introduction pipe. A plasma cutting torch configured to pass through the orifice to the inner and outer surfaces of the chip,
Provided at the inlet portion of the working gas introduction pipe is an introduction pipe fixing bracket having a hollow cylindrical central portion made of copper or copper alloy, and the introduction pipe fixing fitting is formed at the center portion from the outer periphery of the introduction pipe fixing fitting. A plurality of holes communicating with the inlet pipe, the introduction pipe fixing bracket having a convex portion on an outer periphery, and the introduction pipe fixing bracket is provided between a pipe for guiding the working gas and an inlet portion of the working gas introduction pipe, A plasma cutting torch with a copper or copper alloy head fitting provided outside the tube fixing bracket with a cavity in between. 6. The plasma cutting torch according to claim 5, wherein the working gas path axial section of the hole provided in the introduction pipe fixing bracket is larger than the working gas axial section of the working gas introduction pipe. The plasma cutting torch according to claim 5 or 6, wherein the convex portion provided on the outer peripheral portion of the introduction pipe fixing metal fitting has a fin shape or a donut shape.

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