JP2000343228A - Plasma torch and its parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a precision of positioning of a nozzle and an electrode while the nozzle and the electrode are composed as freely detachable. SOLUTION: An electrode 13 is inserted in the inner periphery of a nozzle 17 through a guide made from an insulating material, and elastic O-rings 92 and 93 which allow elements to be relatively positioned are inserted between the outer periphery of the electrode 13 and the inner periphery of the guide, as well as between the outer periphery of the guide and the inner periphery of the nozzle 17, respectively. Thus the precision of the positioning in the horizontal direction is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma torch with improved positioning accuracy between a nozzle and an electrode.

[0002]

2. Description of the Related Art A torch body is provided with a nozzle disposed at the tip of a torch main body so as to cover an electrode with a plasma gas passage therebetween, and a plasma torch for generating a plasma arc between the electrode and a workpiece through an orifice of the nozzle. Are known. In order to cut a material to be cut straight, a plasma arc needs to be perpendicularly incident on the material to be cut, and for that purpose, a nozzle and an electrode need to be accurately positioned in a torch. That is, the nozzle and the electrode must be correctly assembled at a specified position in the torch with the center axes of the nozzles completely aligned with each other and accurately separated by a specified distance in the direction of the center axis. . However, since the nozzle and electrode are consumable parts and must be easily removable from the torch for replacement or assembled to the torch, the nozzle and electrode must be accurately aligned when assembled to the torch. Is not easy.

Conventionally, various techniques have been proposed in order to maintain high accuracy of positional alignment between the nozzle and the electrode. As one of the conventional techniques, the inner peripheral surface of the nozzle and the outer peripheral surface of the electrode are used as fitting surfaces, a step is formed on each fitting surface, an insulator is interposed therebetween, and the nozzle and It has been proposed to position the electrode in the axial direction and the radial direction, and to fix the nozzle to the tip of the torch main body, thereby integrally connecting the electrode to the torch main body. -14
No. 077).

[0004]

According to the above prior art, the smaller the clearance between the nozzle, the electrode and the insulator, the higher the positioning accuracy can be maintained. However, if the clearance of the clearance between the nozzle, the electrode, and the insulator is too small, when the nozzle or the electrode is replaced, it is difficult to fit or disassemble them.
There is a problem that replacement work is difficult.

For this reason, conventionally, the clearance between the components is set to be large, and as a result, there is a problem that the positioning accuracy of the nozzle and the electrode is reduced.

On the other hand, there has been proposed a device in which a nozzle, an electrode, and an insulator are manufactured as an integrated part, and the positioning accuracy of the nozzle and the electrode is remarkably improved.

However, in the case of an integral part,
Even if only one of the nozzles and electrodes is out of life and the other is still usable, all of them must be replaced, and in addition, non-consumable insulators will be replaced together Therefore, there is a problem that the running cost increases.

An object of the present invention is to solve the above-mentioned problems of the prior art and to improve the positioning accuracy of the nozzle and the electrode after the nozzle and the electrode are individually replaceable.

[0009]

According to a first aspect of the present invention, there is provided a plasma torch having a nozzle disposed at a distal end of a torch main body so as to cover an electrode with a plasma gas passage therebetween, and through a nozzle orifice. A plasma torch for generating a plasma arc between an electrode and a material to be cut, comprising: a cylindrical guide made of an insulator fitted between an electrode and a nozzle; and an outer peripheral surface of the electrode and an inner peripheral surface of the guide. Between,
A first elastic material interposed continuously over one circumference or at a plurality of locations on the circumference to adjust the position of the electrode and the guide in the radial direction by elastic expansion and contraction; an outer peripheral surface of the guide and an inner peripheral surface of the nozzle; And a second elastic member interposed continuously over one circumference or at a plurality of locations on the circumference, and performing alignment of the guide and the nozzle in the radial direction by elastic expansion and contraction.

In this plasma torch, the first elastic material is interposed between the outer peripheral surface of the electrode and the inner peripheral surface of the guide.
A second elastic material is interposed between the outer peripheral surface of the guide and the inner peripheral surface of the nozzle. Each of the first and second elastic members is typically one that continuously intervenes over one circumference, for example, an O-ring, but is not necessarily so, and may be provided at a plurality of locations in the circumferential direction. They may be arranged in a dotted manner. The first elastic member has a position alignment (that is, a radial alignment) between the electrode and the guide due to its elastic expansion and contraction (ie,
(Center axis alignment) is performed automatically. The second elastic member performs radial position alignment (that is, center axis alignment) between the guide and the nozzle by its elastic expansion and contraction. As a result, radial alignment of the electrode and nozzle (ie, center axis alignment)
Is done automatically.

In a preferred embodiment, one of the electrode and the nozzle, for example, the electrode, is fixed to the torch body. The other side, that is, for example, the nozzle is free in the radial direction from an external force other than the force applied from the electrode through the first elastic member, the guide, and the second elastic member. That is, in a state where the electrode is fixed to the torch main body, the nozzle does not receive a force other than the positional alignment acting force by the first and second elastic members in the radial direction. Therefore, the first
In addition, the position adjustment action in the radial direction by the second elastic material works effectively without being disturbed by other external forces, and the center axis of the electrode and the nozzle is accurately aligned.

In a preferred embodiment, the nozzle has a first step inside the nozzle to abut one end of the guide to determine the axial positional relationship between the guide and the nozzle. In addition, the electrode has a second step on the outside thereof for determining the axial positional relationship between the guide and the electrode by contacting the other end of the guide. Therefore, the distance between the first step of the nozzle and the second step of the electrode is fixedly determined by the axial dimension of the guide, so that the axial positioning of the nozzle and the electrode is accurately performed. Will be

In a preferred embodiment, the nozzle is held by a retainer cap and fixed to the torch body. When the nozzle is fixed to the torch body, the retainer cap is substantially free from only a pressing force toward the torch body in a direction substantially parallel to the central axis of the nozzle (that is, substantially free of radial and rotational forces). The nozzle is fixed to the torch body (by axial pressing force). Therefore, when the nozzle is fixed to the torch main body by the retainer cap, only the axial force is applied to the nosle and the radial and rotational forces are not applied, so the radial direction by the first and second elastic materials described above is used. Can work effectively,
The center axes of the electrode and the nozzle are accurately aligned.

According to a second aspect of the present invention, a cylindrical guide made of an insulator fitted between a nozzle of a plasma torch and an electrode includes an inner peripheral surface facing an outer peripheral surface of the electrode, and an inner peripheral surface of the nozzle. And an outer peripheral surface facing the surface. On the inner peripheral surface of the guide, a first elastic member for attaching the first elastic material described above is provided.
There is an elastic material attachment part. Also, on the outer peripheral surface of the guide, there is a second elastic material attaching portion for attaching the above-mentioned second elastic material. By fitting the guide to the electrode via the first elastic material and fitting the nozzle to the guide via the second elastic material, as described above,
The position of the electrode and the nozzle in the radial direction are automatically adjusted by the action of the first and second elastic members.

According to a third aspect of the present invention, a cylindrical guide made of an insulator fitted between a nozzle of a plasma torch and an electrode has an inner peripheral surface facing the outer peripheral surface of the electrode.
There is a clearance between the inner peripheral surface of the guide and the outer peripheral surface of the electrode for adjusting the position of the electrode and the guide in the radial direction due to the elastic expansion and contraction of the O-ring inserted therein. This guide is provided with the above-mentioned clearance between the inner peripheral surface and the outer peripheral surface of the electrode and the O pinched therebetween.
The ring facilitates fitting and removal from the electrode, and also automatically aligns the center axis of the guide with the electrode.

According to a fourth aspect of the present invention, an insulating tubular guide fitted between a nozzle and an electrode of a plasma torch has an outer peripheral surface facing an inner peripheral surface of the nozzle. There is a clearance between the outer peripheral surface of the guide and the inner peripheral surface of the nozzle for performing radial alignment of the guide and the nozzle by elastic expansion and contraction of the O-ring inserted therein. This guide is provided with the clearance between the outer peripheral surface and the inner peripheral surface of the nozzle and the O pinched therebetween.
The ring facilitates fitting and removal from the nozzle, and also automatically aligns the center axis of the guide with the nozzle.

According to a fifth aspect of the present invention, a nozzle disposed so as to cover an electrode in a plasma torch via a cylindrical guide made of an insulator has an inner peripheral surface facing an outer peripheral surface of the guide. Prepare. On the inner peripheral surface of the nozzle, there is an elastic material contact portion that comes into contact with the elastic material. The elastic material is interposed between the outer peripheral surface of the guide and the inner peripheral surface of the nozzle, and automatically adjusts the position of the guide and the nozzle in the radial direction by elastic expansion and contraction.

According to a sixth aspect of the present invention, a nozzle disposed so as to cover an electrode in a plasma torch via a cylindrical guide made of an insulator has an inner peripheral surface facing an outer peripheral surface of the guide. Prepare. Further, there is a clearance between the outer peripheral surface of the guide and the inner peripheral surface of the nozzle for performing radial alignment of the guide and the nozzle by elastic expansion and contraction of the O-ring inserted therein. The clearance and the O-ring sandwiched between the clearance allow the nozzle to be easily fitted into and removed from the guide, and the center axes of the nozzle and the guide are automatically aligned.

According to a seventh aspect of the present invention, an electrode arranged so as to be covered by a nozzle via a cylindrical guide made of an insulator in a plasma torch has an outer peripheral surface facing an inner peripheral surface of the guide. Is provided. An elastic material contact portion that contacts the elastic material exists on the outer peripheral surface of the electrode. This elastic material
It is interposed between the inner peripheral surface of the guide and the outer peripheral surface of the electrode, and automatically adjusts the radial position of the guide and the electrode by elastic expansion and contraction.

According to an eighth aspect of the present invention, an electrode disposed so as to be covered by a nozzle via a cylindrical guide made of an insulator in a plasma torch has an outer peripheral surface facing an inner peripheral surface of the guide. Is provided. There is a clearance between the inner peripheral surface of the guide and the outer peripheral surface of the electrode for radially aligning the guide and the electrode by elastic expansion and contraction of the O-ring inserted therein. The clearance and the O-ring sandwiched therebetween allow the electrode to be easily fitted into and removed from the guide, and the center axes of the electrode and the guide to be automatically aligned.

[0021]

FIG. 1 shows a sectional structure of a plasma torch according to an embodiment of the present invention. FIG. 2 shows an enlarged cross-sectional structure of the tip of the plasma torch.

In FIG. 1, reference numeral 1 denotes a torch main body. The torch main body 1 includes an inner sleeve 3 forming a central member, an outer sleeve 5 fitted on the outer periphery of the inner sleeve 3, a holder 7 fitted on the outer periphery of the outer sleeve 5, and an inner sleeve 3. And a nozzle pedestal 9 fitted with a magnet ring 8 therebetween at the tip of the nozzle ring. A bag-shaped electrode body 13 is detachably fitted to the tip of the inner sleeve 3, and the tip of the electrode body 13 serving as a plasma arc generating point is made of a high melting point material capable of withstanding the high heat of the plasma arc. A heat resistant insert 14 is provided (eg, made of hafnium, zirconium, or an alloy thereof for oxygen plasma cutting). The consumption of the electrode occurs at the heat-resistant insert 14.

A cylindrical guide 15 made of an insulating material is fitted on the outer periphery of the electrode body 13, and a cylindrical nozzle 17 tapered toward the tip is fitted on the outer periphery of the guide 15. The base end portion 17a of the nozzle 17 is
Is press-fitted in a detachable state. A pilot arc current wiring (not shown) is connected to the nozzle pedestal 9 of the torch main body 1 (this wiring is provided inside the torch main body and connected to a plasma arc power supply (not shown)). When the base end of the nozzle 17 is pressed against the nozzle pedestal 9, the pressure contact surface between the two becomes an energizing surface, and the nozzle 17 is electrically connected to the nozzle pedestal 9.
Thus, when the pilot arc is ignited, the nozzle 17
A pilot arc current path for supplying a current to the torch main body is provided (in the related art, a retaining cap for holding a member constituting an outer shell of the torch body, for example, a nozzle is used as the pilot arc current path, The pilot arc current path to the nozzle was formed by the nozzle abutting on the ning cap.) Further, on the tip end surface of the nozzle pedestal 9, some elastic electric contact terminals 65 are provided,
7 is attached to the nozzle base 9, the electrical contact terminals 6
5 is bent and comes into contact with the outer surface of the base end portion of the nozzle 17 with a strong elastic force. This electrical contact terminal 6
5, the electrical connection between the nozzle 17 and the nozzle pedestal 9 is more reliably ensured. An orifice 18 having a sufficiently small diameter is formed at the tip of the nozzle 17 for sufficiently squeezing the plasma arc and jetting the jet forward.

As shown in FIG. 2, an annular insulator 19 made of synthetic resin is provided on the outer periphery of the tip portion 17b of the nozzle 17.
A shield cap 21 with a flange is fitted around the outer periphery of the insulator 19 to prevent damage to the nozzle 17 due to spattering during piercing or jumping up of the workpiece (work) 71, for example. Have been. The nozzle 17, the insulator 19, and the shield cap 21 are integrally or fixedly connected to each other, and are configured as a single component shown in FIG. 2 which is not separated by ordinary handling. Therefore, when replacing the nozzle 17,
The nozzle 17, the insulator 19, and the shield cap 21 are replaced together.

Outside these structures, a retainer cap main body 23 for holding components detachable from the torch main body 1, such as the nozzle 17, the guide 15, and the electrode main body 13, so as not to come off from the torch main body 1 is covered. The retainer cap main body 23 has not only a role as a retainer but also a role as an outer shell of the torch. The outer periphery of the shield cap 21 is held by a hook 23a formed at the tip of the lina cap body 23. That is, the step 23b on the base side of the hook 23a is
It is hooked with an O-ring on the first flange 21a,
The step 23c on the tip side of the hook 23a is hooked on the step 21b of the shield cap 21. The rear end of the retainer cap main body 23 extends to the holder 7 side of the torch main body 1 covering the above-described members, and is connected to the holder 7 via a fixing ring 25.

The outer sleeve 5 has a plasma gas passage 31 penetrating therethrough. A plasma gas (for example, a gas mixture of 80 mol% of oxygen and 20 mol% of nitrogen in the case of oxygen plasma cutting) is introduced into the plasma gas passage 31. After passing through the plasma gas passage 31 of the outer sleeve 5, the plasma gas enters the plasma gas passage 33, which is bent in a substantially rectangular shape inside the nozzle pedestal 9, and is swirled (formed in the radial direction by the swirler). A swirling flow is given through a plurality of through holes 35 formed in the guide 15 with a slight inclination in the direction, flows out to the nozzle-electrode passage 37, is turned into plasma by the energy of the arc emitted from the heat-resistant insert 14, and turns. A plasma arc is ejected to the outside through the orifice 18 of the nozzle 17.

The outer sleeve 5 has a secondary gas passage 41 penetrating therethrough. The secondary gas passage 41 bends at a substantially right angle inside the outer sleeve 5, and the outer sleeve 5 and the retainer cap body 2
It communicates with an annular space 43 formed between the three. The secondary gas (for example, a mixed gas or air having a lower oxygen concentration than the plasma plasma gas in the case of oxygen plasma cutting) that has passed through the secondary gas passage 41 enters the annular space 43, from which the retainer cap main body 23 Secondary gas passage cover 24
And flows into a number of secondary gas passages 45 surrounded by. The secondary gas passage 45 forms, for example, a concave groove 23b extending along the axial direction from the base end to the distal end on the outer periphery of the retainer cap main body 23.
And a secondary gas passage cover 24. The secondary gas that has passed through the secondary gas passages 45 is, as shown in an enlarged view in FIG. 2, a through hole formed in the inner wall of the tip end portion of the retainer cap main body 23 corresponding to each secondary gas passage 45. 23c
Through the retainer cap body 23 and the annular space 47 formed between the shield cap 21 and the secondary gas swirler formed in the shield cap 21 (the radius of the secondary gas swirler is changed so that the secondary gas is swirled in the same direction as the plasma gas). Through a plurality of through-holes 21c formed in the shield cap 21 slightly inclined in the circumferential direction with respect to the direction, into the annular space 49 between the nozzle 17 and the shield cap 21 as a swirling flow, and from the opening 21d of the shield cap 21. Spouts outside. As a result, a secondary gas curtain 82 swirling in the same direction is formed around the swirling plasma arc 81.

The holder 7 of the torch main body 1 has a tertiary gas passage 51 penetrating therethrough. The tertiary gas passage 51 is formed in an annular space 5 formed between the holder 7, the retainer cap main body 23 and the fixing ring 25.
Communicate with 3. A tertiary gas passing through the tertiary gas passage 51 (for example, in the case of oxygen plasma cutting, a mixed gas or a pure oxygen gas having an oxygen concentration higher than that of the secondary gas) enters the annular space 53, from which the retainer cap body 23 and the A plurality of tertiary gas passages 5 surrounded by a tertiary gas passage cover 54
Flow through 5. This tertiary gas passage 55 is, for example,
A concave groove 23d is formed on the outer periphery of the retainer cap body 23 from the base end to the distal end thereof along the axial direction thereof, and the tertiary gas passage cover 54 is placed over the concave groove 23d.

The tertiary gas passing through the tertiary gas passage 55 is supplied to a tertiary gas swirler (a tertiary gas and a plasma gas or a secondary gas) formed at the tip of the retainer cap body 23 as shown in an enlarged view in FIG. The swirling flow is provided through a plurality of through holes (56) penetrating the tip end portion of the retainer cap main body 23 while being slightly inclined in the circumferential direction with respect to the radial direction so as to swirl in the same direction, and strikes the outer periphery of the shield cap 21. As a result, a tertiary gas curtain 83 is formed around the secondary gas 82.

The secondary gas passages 45 and the tertiary gas passages 55 formed in the retainer cap main body 23 are alternately arranged at substantially equal intervals radially about the torch center axis.

The secondary gas passage 45 or the tertiary gas passage 55 is not limited to the one formed through the inside of the retainer cap main body 23, and is not limited to the one formed through the retainer cap main body 2.
A configuration may be adopted in which an external passage is turned to the outside of 3, and a secondary gas or a tertiary gas is guided to the periphery of the plasma arc through the external passage. Further, the secondary gas and the tertiary gas are the swirl flow in the present embodiment, but may be a radial air flow (not a swirl flow) in which the gas passage can be easily manufactured with a slight sacrifice of the merit of the swirl flow.

A cooling water passage 61 penetrating therethrough is formed inside the inner sleeve 3. Cooling water is guided into the cooling water passage 61 from outside the torch body 1. This cooling water enters the bag-shaped electrode body 13 and cools the tip of the electrode body 13, as shown in FIG. 2, where the pipe 61 a forming the cooling water passage 61 and the inner periphery of the electrode body 13 are connected. The nozzle 1 flows backward through the annular space between the nozzles 1 through the relay passage in the outer sleeve 5 (not shown).
The cooling water flows out into a cooling water passage 63 formed outside of the cooling water passage 7.

In addition to most of the outer peripheral surface of the nozzle 17 facing this cooling water passage 63, the flange 21a of the shield cap 21 and most of the inner peripheral surface of the retainer cap body 23 simultaneously face. Each of these members 17, 2
The cooling water 1 and 23 are cooled directly and forcibly by the cooling water circulating through the cooling water passage 63. Since the hottest part is near the tip of the nozzle 17, the insulator 19 and the shield cap 21 are designed so that the cooling water can be introduced to the vicinity of the tip as much as possible. It is desirable to attach to the tip portion 17b.

The cooling water flowing out of the cooling water passage 63 is discharged to the outside of the torch main body through a cooling water discharge passage in the outer sleeve 5 not shown.

The cooling water circulating in the cooling water passage 63 is sealed at the boundaries between the components surrounding the cooling water passage 63 by O-rings inserted at those boundaries. However, at the boundary between the nozzle 17, the insulator 19, and the shield cap 21 formed as an integral single part, the resin insulator 19 seals water as follows. That is, as shown in FIG. 2, an annular step 21e for holding the insulator 19 is provided on the inner periphery of the shield cap 21, and a ring-shaped projection 21f is formed on the surface of the step 21e. Have been. The protrusion 21f cuts into the lower surface of the insulator 19 to seal the boundary between the shield cap 21 and the insulator 19. The annular step 17c formed on the outer periphery of the nozzle 17 fits with the annular step 19a existing on the inner periphery of the insulator 19. Nozzle 17
The cross-section of the outer corner 17d of the step 17c has a slightly acute angle wedge shape, and the corner 17d is the step 1 of the insulator 19.
9a is cut into the inner corner to seal the boundary between the insulator 19 and the nozzle 17.

In the above configuration, since the nozzle 17 and the electrode body 13 are consumables, the nozzle 17 and the electrode body 1
3 is configured to be detachable and easily replaceable. That is, when the nozzle 17 and the electrode main body 13 are detached from the torch main body from the state shown in FIG. 1, the fixing ring 25 of the torch main body is loosened, and the retainer cap main body 23 is detached from the torch main body. The body 13 can be easily removed by its own weight naturally (or by slightly pulling in a direction parallel to the torch axis). on the other hand,
When assembling the nozzle 17 and the electrode main body 13 to the torch main body, the base end of the electrode 13 is fitted into the distal end of the inner sleeve 3 of the torch main body, and the guide 15 is inserted into the distal end of the electrode 13.
And the nozzles 17 are externally fitted to the guides 15, and the retainer cap main body 23 is put on the outsides of the nozzles 17. Then, the hook 23a at the tip of the retainer cap body 23 is connected to the step 21b of the shield cap 21 at the tip of the nozzle 17.
Then, the base end of the retainer cap main body 23 is hooked on the fixing ring 29 of the torch main body, and the fixing ring 25 is tightened to lift the retainer cap main body 23 toward the torch main body. As a result, the retainer cap body 23 pushes the tip of the nozzle 17 toward the torch body in a direction parallel to the torch axis, so that the nozzle 17 is pressed against the nozzle pedestal 9 and is fixed on the nozzle pedestal 9. 17 pushes the electrode main body 13 toward the torch main body in a direction parallel to the torch axis via the guide 15, so that the electrode main body 13 is pressed and fixed to the inner sleeve 3. When the nozzle 17 and the electrode main body 13 are assembled to the torch main body in this way, in the present embodiment, the nozzle 17 and the electrode main body 13 are positioned with high accuracy in both the torch axial direction and the radial direction. I have. This will be described in detail below.

FIG. 3 schematically shows an assembly structure of the nozzle 17 and the electrode body 13 in the present embodiment, and shows it in an exploded manner for easy understanding.

A body portion 91 having a substantially constant diameter is formed at the base end portion 17b of the nozzle 17, and the guide 15 is fitted on the inner periphery of the body portion 91 with an elastic O-ring 92 interposed therebetween. The electrode body 13 is fitted on the inner periphery of the electrode 15 with an O-ring 93 having elasticity interposed therebetween. The electrode body 13 is fitted into the recess 3a of the inner sleeve 3 with an elastic O-ring 94 interposed therebetween.

As described above, the nozzle 17 and the electrode body 1
To remove 3 for replacement, first
Then, the fixing ring 25 is loosened, and the retainer cap main body 23 held by the fixing ring 25 is removed toward the tip of the torch. When the retainer cap main body 23 is removed, the integral parts of the shield cap 21, the insulator 19, the nozzle 17, the guide 15, and the electrode main body 13 are sequentially and easily removed in the axial direction. The disassembly is thus very simple.

After the parts are replaced, when assembling the members, the assembly is performed in a completely reverse procedure to the removal procedure. At this time, the above-described O-rings 92 to 94 play an important role in radial positioning (that is, center axis alignment and centering) between the nozzle 17 and the electrode main body 13.

That is, the O-rings 92 to 94 have such a property that shrinkage allowances of respective portions are substantially equal in the circumferential direction. Therefore, when the electrode main body 13 and the guide 15 are assembled with the O-ring 93 interposed therebetween, the central axis L1 of the electrode main body 13 and the central axis of the guide 15 are automatically and accurately determined due to the nature of the O-ring 93. Matches. When the guide 15 and the nozzle 17 are assembled with the O-ring 92 interposed therebetween,
Due to the nature of the O-ring 92, the central axis of the guide 15 and the central axis L2 of the nozzle 17 automatically and accurately match. As a result, the center axis L1 of the electrode body 13 and the nozzle 1
7 automatically and accurately coincides with the central axis L2. Next, when the electrode main body 13 is fitted into the recess 3a of the inner sleeve 3 of the torch main body with the O-ring 94 interposed therebetween, the nature of the O-ring 94 causes the central axis L3 of the inner sleeve 3 (that is, the torch main body). Center axis) and electrode body 1
3 automatically coincides with the central axis L1. As a result, the center axis L1 of the electrode body 13, the center axis L2 of the nozzle 17, and the center axis L3 of the torch body automatically and accurately match.

As shown in FIGS. 1 and 2, the O-rings 92 to 94 are accommodated in O-ring grooves formed on the outer peripheral surface or the inner peripheral surface of each component. Since the coaxiality of the groove bottoms of these O-ring grooves has a great effect on the above-mentioned centering, it is desirable to increase the accuracy to about 0.02 mm.
The coaxiality of the ring groove bottom is about 0.05 mm).

Next, the retainer cap main body 23 is provided with the shield cap 2 around the distal end of the nozzle 17 at the distal end.
While holding 1, it is fixed to the holder 7 of the torch main body by the fixing ring 25. At this time, the retainer cap main body 23 only applies a pressing force to the nozzle 17 in a direction parallel to the central axes L1 to L3 described above.
No radial or rotational forces are applied. Furthermore, nozzle 1
7 is pressed against the nozzle pedestal 9 by the retainer cap main body 23, but the contact surface between the nozzle 17 and the nozzle pedestal 9 is a surface perpendicular to the axial direction. But no radial forces. Thus, the nozzle 17
There is no component on the outside of the nozzle that applies a force other than the axial direction to the nozzle 17, in particular, a radial force. That is, the nozzle 17 is in a free state in the radial direction without receiving any external force other than the force of the O-rings 92 to 94. In other words, the nozzle 17 is in a free state so that position adjustment by the O-rings 92 to 94 in the radial direction is permitted. Therefore, the above-described O-ring 9
The alignment action by the 2-94 works effectively without being hindered by radial external forces. In this way, the highly accurate positional alignment (that is, the coincidence of the center axis) of the electrode body 13 and the nozzle 17 in the radial direction by the O-rings 92 to 94 is effectively performed without being obstructed by an external force.

On the other hand, regarding the positioning of the nozzle 17 and the electrode body 13 in the axial direction, the step 9 on the inner periphery of the nozzle 17 is used.
5. This is achieved by the dimensions of the flange 96 of the electrode body 13, and the guide 15 sandwiched between the step 95 and the flange 96. That is, at the time of assembling, the distal end surface 97 of the guide 15 comes into contact with the step 95 on the inner periphery of the nozzle 17, and this guide 1
5 is a flange 96 formed on the electrode body 13.
Is held down. Accordingly, the axial distance between the step portion 95 of the nozzle 17 and the flange 96 of the electrode body 13 is determined by the axial length of the guide 15, so that the relative position of the nozzle 17 and the electrode body 13 in the axial direction is determined. Is automatically and accurately determined.

Further, a point to be noted in the configuration shown in FIG.
A sufficiently large clearance exists at the boundary between the components into which the O-rings 92 to 94 are inserted, because the O-rings 92 to 94 are used for radial alignment. That is, between the inner peripheral surface of the distal end of the inner sleeve 3 and the outer peripheral surface of the base end of the electrode body 13, between the outer peripheral surface of the distal end of the electrode body 13 and the inner peripheral surface of the guide 15, There is a large clearance between the outer peripheral surface of the distal end portion and the inner peripheral surface of the base end portion of the nozzle so that these components do not directly touch each other. With this clearance, the above-described radial position alignment action by the O-rings 92 to 94 works effectively, and the parts can be easily separated and fitted easily, so that the replacement operation is easy. In addition, O-rings 92-9
4 has a circular cross-section, so that there is no large resistance when separating and fitting parts together, which also facilitates replacement work.

As is apparent from the above description, in this embodiment, the nozzle 17 and the electrode body 13 are configured to be detachable, and when they are assembled to the torch body,
The positioning of the nozzle 17 and the electrode body 13 in the radial direction can be improved by the action of the O-rings 92 to 94, and a guide is provided between the step 95 on the inner periphery of the nozzle 17 and the flange 96 formed on the electrode body 13. By sandwiching 15, the positioning accuracy of the nozzle 17 and the electrode body 13 in the axial direction can be improved.

The O-rings 92 to 94 are not limited to these. As a substitute, a member having elasticity equivalent to an O-ring can be used. Alternatively, instead of a ring member existing continuously around the inner peripheral surface or the outer peripheral surface of the component like an O-ring, a plurality of elastic members arranged at a plurality of positions in the circumferential direction of the inner peripheral surface or the outer peripheral surface of the component are used. A block may be used to align the position in the radial direction by uniform elastic expansion and contraction of the elastic blocks at a plurality of locations on the periphery.

Although the present invention has been described based on one embodiment, it is apparent that the present invention is not limited to this.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a plasma torch according to the present invention.

FIG. 2 is a cross-sectional view showing a tip end of the plasma torch of FIG. 1 in an enlarged manner.

FIG. 3 is an exploded schematic view schematically showing an assembling structure of a nozzle and an electrode main body in the plasma torch of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Torch main body 3 Inner sleeve 5 Outer sleeve 7 Holder 9 Nozzle pedestal 13 Electrode main body 15 Guide 17 Nozzle 18 Orifice 19 Insulator 21 Shield cap 23 Retainer cap main body 92, 93, 94 O-ring 95 Step 96 Flange

Claims (11)

[Claims] 1. A plasma torch having a nozzle disposed at a tip end of a torch main body so as to cover an electrode through a plasma gas passage and generating a plasma arc between the electrode and a workpiece through an orifice of the nozzle. A cylindrical guide made of an insulator fitted between the electrode and the nozzle, between the outer peripheral surface of the electrode and the inner peripheral surface of the guide, continuously interposed over one circumference or Interposed at multiple locations,
A first elastic material that aligns the electrode and the guide in the radial direction by elastic expansion and contraction, and continuously interposes or extends over one circumference between an outer peripheral surface of the guide and an inner peripheral surface of the nozzle; And a second elastic material interposed at a plurality of locations and performing radial alignment of the guide and the nozzle by elastic expansion and contraction. 2. One of the electrode and the nozzle is fixed to the torch main body, and the other is in a radial direction other than a force applied from the one through the guide and the first and second elastic members. The plasma torch according to claim 1, wherein the plasma torch is free from external force. 3. A nozzle having a first step inside the nozzle for abutting against one end of the guide to determine an axial positional relationship between the guide and the nozzle, and the electrode outside the nozzle. The plasma torch according to claim 1 or 2, further comprising a second step portion that abuts on the other end of the guide to determine an axial positional relationship between the guide and the electrode. 4. The apparatus further comprises a retainer cap for holding the nozzle and fixing the nozzle to the torch main body, wherein the retainer cap is a force directed to the torch main body in a direction parallel to a central axis of the nozzle. The nozzle is fixed to the torch main body by a pressing force substantially not including a radial direction and a rotational direction.
3. The plasma torch according to any one of 3. 5. A cylindrical guide made of an insulator fitted between a nozzle of a plasma torch and an electrode, an inner peripheral surface facing an outer peripheral surface of the electrode, and an outer peripheral surface facing an inner peripheral surface of the nozzle. And a first elastic member that is interposed between the inner peripheral surface of the guide and the outer peripheral surface of the electrode and that aligns the electrode and the guide in the radial direction by elastic expansion and contraction. First for
The elastic member mounting portion is provided on the inner peripheral surface of the guide, and is positioned between the outer peripheral surface of the guide and the inner peripheral surface of the nozzle to elastically expand and contract to align the guide and the nozzle in the radial direction. And a second elastic member for attaching a second elastic member on the outer peripheral surface of the guide. 6. A cylindrical guide made of an insulator fitted between a nozzle of a plasma torch and an electrode, comprising: an inner peripheral surface facing an outer peripheral surface of the electrode; and an inner peripheral surface of the guide and the electrode. A guide for a plasma torch having a clearance between the outer peripheral surface of the plasma torch and the O-ring inserted therein to adjust the position of the electrode and the guide in the radial direction by elastic expansion and contraction. 7. A cylindrical guide made of an insulator fitted between a nozzle and an electrode of a plasma torch, comprising: an outer peripheral surface facing an inner peripheral surface of the nozzle; A plasma torch guide having a clearance between the inner peripheral surface and the O-ring inserted therein for elastic alignment of the guide and the nozzle in the radial direction. 8. A nozzle disposed in a plasma torch so as to cover an electrode via a cylindrical guide made of an insulator, comprising: an inner peripheral surface facing an outer peripheral surface of the guide; An elastic member that is interposed between an outer peripheral surface and an inner peripheral surface of the nozzle to elastically expand and contract to align the guide and the nozzle in a radial direction; The nozzle of the plasma torch above. 9. A nozzle disposed in a plasma torch so as to cover an electrode via a cylindrical guide made of an insulator, comprising: an inner peripheral surface facing an outer peripheral surface of the guide; A nozzle for a plasma torch, having a clearance between an outer peripheral surface and an inner peripheral surface of the nozzle for performing radial alignment of the guide and the nozzle by elastic expansion and contraction of an O-ring inserted therein. 10. An electrode disposed in a plasma torch so as to be covered by a nozzle via a cylindrical guide made of an insulator, comprising: an outer peripheral surface facing an inner peripheral surface of the guide; An elastic material interposed between an inner peripheral surface of the electrode and an outer peripheral surface of the electrode to elastically expand and contract to adjust the position of the guide and the electrode in the radial direction; Plasma torch electrode on the surface. 11. An electrode disposed in a plasma torch so as to be covered by a nozzle via a cylindrical guide made of an insulator, comprising: an outer peripheral surface facing an inner peripheral surface of the guide; An electrode of a plasma torch having a clearance between an inner peripheral surface of the electrode and an outer peripheral surface of the electrode for performing radial alignment of the guide and the electrode by elastic expansion and contraction of an O-ring inserted therein. .