JPH11221675A - Plasma torch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent as much as possible electric corrosion of an electrode holder and a nozzle holder of a plasma torch in a style of generating a plasma arc by energizing an electrode and a nozzle. SOLUTION: An insulating body 6 is made to intervene between an electrode holder 1 to energize an electrode 3 and a nozzle holder 8 to energize a nozzle 7, and a cooling water passage 9 is formed through each of the members 1,6,8. Fitting parts 1a, 6c, 8a are formed at constituting position of the cooling water passage 9 in each of the members 1, 6, 8, and to these fitting parts a cylindrical connecting member 20 is fitted to form a passage 9. On the outer peripheral surface of the connecting member 20, grooves 20a are formed, on which O-rings 21 are fixed. By fitting the connecting member 20 to each of the fitting parts 1a, 6c, 8a, the distance between the electrode holder 1 and the nozzle holder 8 is enlarged. The connecting member 20 is made of an insulating material having an electrical insulating ability, a material with big electric resistance, or a materiale free from absorptivity for water or with corrosion resistance in addition to the above proprerties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma torch capable of preventing leakage of cooling water for cooling a plasma torch including an electrode and a nozzle.

[0002]

2. Description of the Related Art A plasma torch discharges gas between an electrode and a nozzle and gasifies a gas supplied to a passage formed between the electrode and a nozzle. This plasma arc is used to process a steel plate, an aluminum plate or a stainless steel plate. Processing such as cutting, welding, or thermal spraying is performed by spraying the material toward the material. A plasma torch is a non-transitional torch that discharges between an electrode and a nozzle to form a plasma arc, and a discharge between an electrode and a nozzle forms a pilot arc and then discharges between an electrode and a non-working material. A transfer torch for forming a plasma arc has been put to practical use.

As described above, in the plasma torch, both the non-transfer type and the transfer type discharge electricity between the electrode and the nozzle. Therefore, both are insulated inside the plasma torch. The formed plasma arc is at a high temperature of about 30,000 ° C., and the temperature of the plasma torch rises due to the radiation of the plasma arc. Have been.

FIG. 2 shows a configuration of a transfer type plasma torch. That is, in the plasma torch, an insulating material 55 made of synthetic resin is arranged between an electrode base 52 for energizing the electrode 51 and a nozzle base 54 for energizing the nozzle 53.
A cooling water channel 56 is formed penetrating the 52, the insulating material 55, and the nozzle base 54. At both ends in the axial direction of the insulating material 55, cylindrical grooves 55a and 55b around the axis 57 are formed.
The electrode table 52 and the nozzle table 54 are fitted to a and 55b, respectively.
Further, O-rings 58 are provided at contact portions between the electrode stand 52 and the insulating member 55 and at contact portions between the insulating member 55 and the nozzle stand 54 in the cooling water passage 56, respectively. It is essential that the electrode table 52 and the nozzle table 54 each have conductivity, and brass is used as a material.

In the plasma torch constructed as described above, the cooling water supplied from the center of the electrode base 52 cools the electrode 51 from the back side according to the arrow shown in FIG.
From the electrode table 52 to the nozzle table 54 via the insulating material 55, the nozzle
After cooling around 53, it is discharged through a similar path,
In this circulation process, the electrode 51 and the nozzle 53 can be cooled.

[0006]

SUMMARY OF THE INVENTION In a plasma torch,
It requires that pure water be used as cooling water. However, pure water is generally used circulating because of its high price. For this reason, impurities are dissolved in the pure water to have a slight conductivity, and when discharging between the electrode and the nozzle, there is a problem that electricity is supplied between the electrode table and the nozzle table through the cooling water.

Further, in the case of the transfer type plasma torch, current is supplied between the electrode base and the nozzle base not only at the time of discharge between the electrode and the nozzle, but also during the discharge between the electrode and the workpiece. Problems have arisen. That is, there is a problem that a current to be discharged between the electrode and the workpiece or a shunt occurs through the cooling water.

In particular, the electrode base and the nozzle base are required to have conductivity, and are generally formed using a brass (C3604) which is a copper-based metal having a relatively high ionization tendency. . For this reason, the electrode base and the nozzle base are electrolytically corroded due to the energization, and the contact surfaces of the electrode base and the nozzle base with the respective insulating materials are damaged. Leaks into the other part of the plasma torch, and the electric leak may cause the plasma torch itself to be melted and damaged.

This problem can be prevented by increasing the distance between the electrode table and the nozzle table. However, in this case, it is necessary to increase the total length of the plasma torch, which is not preferable because it increases the cost.

It is an object of the present invention to provide a plasma torch capable of preventing leakage of cooling water by preventing electric corrosion of an electrode table and a nozzle table as much as possible.

[0011]

In order to solve the above-mentioned problems, a plasma torch according to the present invention is integrated with an electrode base for energizing an electrode and a nozzle base for energizing a nozzle with an insulator interposed therebetween. In a plasma torch having a cooling water passage formed through the electrode base, the insulator, and the nozzle base through the electrode base, the insulator, and the nozzle base, a connecting portion between the electrode base and the insulator in the water path, and the insulator and the nozzle base And a connecting member formed of an insulating material or a material having a large electric resistance is arranged at a connecting portion with the connecting member.

In the above-mentioned plasma torch, a connecting member formed of an insulating material or a material having a high electric resistance is provided at a connecting portion between the electrode stand and the insulator and a connecting portion between the insulator and the nozzle stand in the cooling water passage. By arranging the connecting member made of a material having no water absorption or corrosion resistance in addition to the property, the length of the insulating portion of the cooling water passage can be substantially extended, thereby making it possible to reduce the electric power as much as possible. Corrosion can be prevented.

In the above-mentioned plasma torch, the connecting member is formed in a cylindrical shape, and a fitting portion for fitting the connecting member to the electrode base, the insulator and the nozzle base is formed, and the connecting member is attached to the fitting portion. It is preferable that the fitting be performed, and furthermore, it is preferable that a sealing material be disposed between the outer circumferential surface of the connection member and the inner circumferential surface of the fitting portion formed on the electrode stand, the insulator, and the nozzle stand.

As described above, the connecting members are formed in a cylindrical shape, and these connecting members are respectively fitted to a fitting portion formed on the electrode base and the insulator and a fitting portion formed on the insulator and the nozzle base. With such arrangement, the distance between the electrode table and the nozzle table can be increased, and electrolytic corrosion can be prevented as much as possible.

The outer peripheral surface of each connecting member, the inner peripheral surface of the fitting portion formed on the electrode base, the inner peripheral surface of the fitting portion formed on the insulator, and the inner peripheral surface of the fitting portion formed on the nozzle base. By arranging the seal material between the electrode base and the electrode base, even if the electrolytic corrosion occurs on the surface of the nozzle base facing the insulator,
There is no damage at the location where the sealing material is disposed, and the cooling water does not leak to other parts of the plasma torch.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the above-mentioned plasma torch will be described below with reference to the drawings. FIG. 1 is a sectional view of a plasma torch according to the present embodiment.

The plasma torch A shown in FIG. 1 is configured to be detachable from a base (not shown) provided with a cooling water supply channel and a drain channel, a plasma gas supply channel, and a current-carrying member. It is configured to be mounted on the base attached to a holder provided in a processing device such as a device and to perform a target processing.

In the figure, an electrode base 1 is arranged at the rear end side (right side in the figure) of the plasma torch A.
A guide pipe 2 for guiding the cooling water supplied to the center of the guide pipe 2 is attached, and an electrode 3 is detachably attached to the outer periphery of the guide pipe 2 at the end on the tip side (left side in the figure). The rear end of the conductive pipe 4 is fitted to the electrode base 1.

In the above configuration, electricity is supplied to the electrode 3 from the electrode base 1 via the conductive pipe 4. After the cooling water supplied from the center of the electrode base 1 by the guide pipe 2, the electrode 3, and the conductive pipe 4 cools the electrode 3, the electrode base 1
The cooling water passage 5 for the electrode is formed.

The outer periphery of the electrode base 1 is fitted into a fitting groove 6a formed on the rear end side of the insulator 6. This insulator 6
A nozzle base 8 for energizing the nozzle 7 is fitted in a fitting groove 6b formed on the front end side of the nozzle. Therefore, the electrode table 1 and the nozzle table 8 are electrically insulated by being connected to each other via the insulator 6. Further, two cooling water flow passages 9 are formed through the electrode base 1, the insulator 6, and the nozzle base 8, and one of the cooling water flow passages 9 is provided in the electrode cooling water passage 5.
, And the other cooling water flow passage 9 is connected to a drainage passage of the base.

The nozzle 7 is fitted on the tip side of the nozzle base 8 and is mounted between the nozzle 3 and the electrode 3 via a centering stone 10 to ensure concentricity with the electrode 3.
Furthermore, it is fixed by an inner cap 11 screwed to the nozzle base 8.

In the above configuration, the nozzle 7 is energized from the nozzle base 8 and the inner cap 11. Further, a nozzle cooling chamber 12 for connecting the two cooling water passages 9 and cooling an outer peripheral portion of the nozzle 7 is formed by the nozzle 7, the nozzle base 8, and the inner cap 11. Electrode 3
Between the nozzle and the nozzle 7, a plasma chamber 13 in which the supplied plasma gas is turned into plasma is formed. The plasma chamber
A plasma gas supply path (not shown) formed in the electrode stand 1 and the insulator 6 is connected to 13.

The plasma torch A according to the present embodiment is configured to be capable of injecting a secondary airflow surrounding a plasma arc. For this purpose, an outer nozzle 14 is provided outside the nozzle 7, and the outer nozzle 14 is fixed to the outer cylinder 16 by a cap 15, and the inner cap 11,
A secondary airflow chamber 17 is formed by the cap 15. The secondary airflow chamber 17 is connected to a secondary airflow gas supply passage (not shown) formed in the electrode stand 1 and the insulator 6.

In the above configuration, a connecting member 20 formed in a cylindrical shape is disposed at each connecting portion of the electrode base 1, the insulator 6, and the nozzle base 8 constituting the cooling water flow passage 9.
The connecting member 20 is formed in a cylindrical shape having a predetermined length, and has two grooves 20 at a predetermined interval on the outer peripheral surface.
a is formed, and an O-ring 21 is mounted in the groove 20a.

For this reason, the connecting members 20 are located at positions corresponding to the cooling water flow passages 9 of the electrode base 1, the insulator 6, and the nozzle base 8, respectively.
Are formed with fitting portions 1a, 6c, 8a. The fitting portions 1a, 6c, 8a are each formed of a circular groove, and the inner peripheral surface is a contact surface with the O-ring 21 mounted on the connecting member 20. Therefore, it is not necessary to directly contact the bottom surfaces of the fitting portions 1a, 6c, 8a and both end surfaces of the connection member 20.

The electrode table 1 and the nozzle table 8 must have conductivity, and in this embodiment, brass (C3604) is used. It is essential that the insulator 6 has a sufficiently high insulating property. In this embodiment, polyether ether ketone (PEEK) is used in consideration of workability in addition to the insulating property.

The connecting member 20 is made of an insulating material or a material having a high electric resistance, or a material having no water absorption or corrosion resistance in addition to the above properties. Connection member 20
It is possible to use PEEK as the insulating material for forming the same as the insulator 6, and it is also possible to use ceramics. In addition, stainless steel can be used as a material having high electric resistance, no water absorption, and corrosion resistance.

That is, the material having a large electric resistance constituting the connecting member 20 only needs to have a large electric resistance, which is a material of the electrode table 1 and the nozzle table 8, and the electrode table 1 and the nozzle table 8 are made of brass. In this case, it is possible to use stainless steel as the material of the connection member 20.

As described above, the electrode member 1 and the insulator 6 and the insulator 6 and the nozzle table 8 in the cooling water flow passage 9 are connected by the connecting member 20 so that the cooling water flow passage 9 has The distance between the electrode base 1 and the nozzle base 8 can be substantially increased. Therefore, even when the cooling water has conductivity, it is possible to prevent the occurrence of electrolytic corrosion as much as possible.

Even when the electrode base 1 and the nozzle base 8 are subject to electrolytic corrosion, the electrolytic corrosion damages only the bottom surfaces of the fitting parts 1a and 8a formed on the electrode base 1 and the nozzle base 8. It is. However, the seal between the electrode base 1 and the insulator 6 and the seal between the insulator 6 and the nozzle base 8 are not formed on the bottom surfaces of the fitting portions 1a and 8a, but on the outer peripheral surface of the connecting member 20 and the inner circumferential surfaces of the fitting portions 1a and 8a. Therefore, good sealing performance can be maintained regardless of damage to the electrode table 1 and the nozzle table 8 due to the electrolytic corrosion.

Therefore, the electrode table 1 in the cooling water flow passage 9
Even if electrolytic corrosion occurs in the nozzle base 8, the cooling water does not leak to other parts of the plasma torch A.

[0032]

As described above in detail, in the plasma torch according to the present invention, the distance between the electrode base and the nozzle base in the cooling water passage formed through the electrode base, the insulator and the nozzle base. Can be expanded. For this reason, even when the cooling water flowing through the water channel is energized,
Electrolytic corrosion of the electrode table and the nozzle table can be prevented as much as possible.

Even in the case where the electrode base and the nozzle base are damaged by the electric corrosion, the sealing material is formed between the outer peripheral surface of the connection member and the fitting part formed on the electrode base, the insulator, and the nozzle base. The cooling water does not leak to other parts irrespective of the damage because the cooling water is arranged between the cooling water and the peripheral surface.

[Brief description of the drawings]

FIG. 1 is a sectional view of a plasma torch.

FIG. 2 is a cross-sectional view of a conventional plasma torch.

[Explanation of symbols]

 A Plasma torch 1 Electrode base 1a, 6c, 8a Fitting part 2 Guide pipe 3 Electrode 4 Conductive pipe 5 Electrode cooling water path 6 Insulator 6a, 6b Fitting groove 7 Nozzle 8 Nozzle base 9 Cooling water flow path 10 Centering stone 11 Inner Cap 12 Nozzle cooling chamber 13 Plasma chamber 14 Outer nozzle 15 Cap 16 Outer cylinder 20 Connecting member 20a Groove 21 O-ring

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Seiji Mizuno Koike Oxygen Industries Co., Ltd. 3-35-16 Nishikoiwa, Edogawa-ku, Tokyo

Claims (4)

[Claims] An insulating member is interposed between an electrode base for energizing an electrode and a nozzle base for energizing a nozzle, and is integrally formed with each other. Cooling water is passed through the electrode base, the insulator and the nozzle base. In the plasma torch in which the water channel is formed, a connection member formed of an insulating material or a material having a large electric resistance at a connection portion between the electrode base and the insulator and a connection site between the insulator and the nozzle base in the water channel Plasma torch characterized by having arranged. 2. The connecting member is formed in a cylindrical shape, and a fitting part for fitting the connecting member to the electrode base, the insulator, and the nozzle base is formed, and the connecting member is fitted to the fitting part. The plasma torch according to claim 1, wherein: 3. A sealing material is disposed between an outer peripheral surface of the connection member and an inner peripheral surface of a fitting portion formed on the electrode stand, the insulator and the nozzle stand. The plasma torch described in 1. 4. The plasma torch according to claim 1, wherein the connecting member is formed of a material having no water absorption or a material having corrosion resistance.