JPH10263831A - Plasma cutting torch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of short circuit between an electrode and a nozzle tip in the case of tightening defect of shield cup or loosening during working by mounting a projecting body at least on either of the inner dircumferential surface of nozzle tip of the part into which an electrode is inserted or the outer circumferential surface of the part into which an electrode is inserted to form an insulation state between the said surface and the other surface. SOLUTION: A circular gloove 3 is provided on the outer circumferential surface of the top end of electrode 2 inserted into a nozzle tip 5, a ring-shaped projecting body 4 formed of silicone rubber is fitted to the circular gloove 3 and is fixed there. This enables to secure a clearance between the electrode 2 and the nozzle tip 5, and thereby generation of short circuit between these parts is surely prevented. By the way, the ring-shaped projection body 4 is provided with glooves on its outer circumferential surface to secure flow passages of working gas. In here it is disirable to form the gloove slant to the direction of axis of electrode 2 so as to let the working gas be swirling flows when passing through the glooves and give a sharp cutting surface to the plasma arc without expanding the arc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a plasma cutting torch.

[0002]

2. Description of the Related Art In plasma cutting, a base material is cut by a cutting current and a working gas for forming plasma, and an argon-based gas or a nitrogen-based gas is used as a working gas in addition to air. In this structure, a cutting current flows between the electrode rod as a negative electrode and the base material as a positive electrode, and a working gas is ejected from a nozzle tip. For example, FIG.
As shown in FIG. 1, there are various types of conventional torches 21 for plasma cutting. FIG. 2A shows a state in which the electrode rod 22 is screwed and fixed to the holder 24 and the nozzle tip 23 is fixed.
FIG. 2B shows a structure in which the electrode rod 22 is inserted into the holder 24 and loaded, and the nozzle tip 23 is fixed by tightening with the shield cup 27. The holder 24 for mounting the electrode rod 22 is
It is formed of a conductor provided with a working gas supply section for the purpose of supplying a current to the cutting gas and supplying a working gas for cutting.

[0003] By making the mounting portion of the electrode rod 22 a flow path of the working gas, there is an effect that the electrode rod 22 is cooled. In the torch having a structure in which the electrode rod 22 is inserted into the holder 24 and loaded, the nozzle tip 23 is fitted to an exposed portion of the electrode rod 22 loaded in the holder 24 via a baffle 25 formed of an insulating material. The tip portion is inserted into the tip portion of the nozzle tip 23.
The electrode rod 22 is fixed by tightening and fixing the nozzle tip 23 with a shield cup 27 which is screwed and fixed to the housing 26 of the torch 21.

[0004]

Generally, in a torch for plasma cutting, the nozzle tip has a structure in which the periphery is covered with a shield cup or the like, so that there is a problem that visibility is low. Therefore, although the visibility can be improved by lengthening the nozzle tip, the electrode rod must be lengthened accordingly. This means that the gap between the electrode rod and the peripheral surface of the nozzle tip is generally 0.3 mm
When the length of the nozzle tip exceeds about 15 mm in the conventional torch, a short circuit easily occurs between them, and there is a problem that a smooth operation cannot be performed and cutting cannot be performed. A short circuit occurs when the threaded portion of the electrode rod or the nozzle tip is loosened, or when the fastening of the shield cup is loosened or insufficient, and the plasma is interrupted. Short-circuiting may occur when the torch is not fully tightened when assembling, or when a foreign object is caught or loosened during long working hours.
As a result, the cut surface of the work became dirty.

When a short circuit easily occurs between the nozzle tip and the electrode bar, a discharge is generated in a portion where the electrode bar is loaded, which also causes a high temperature. When this part becomes high temperature, the chip is instantaneously burned out and adversely affects the shield cup. In the worst case, the body of the torch body may be burned by the high temperature. Particularly, in recent years, ceramic shield cups with excellent heat resistance are often used, and the metal parts such as electrode rods and holders become hot due to electric discharge and expand, causing the so-called heat shock that damages the ceramic members. Would be.

[0006]

In view of the above points, the present inventor has accomplished the present invention as a result of intensive research. The feature of the present invention is that the inside of a nozzle tip for ejecting plasma gas is provided. In a torch for plasma cutting with a structure that allows a part of the electrode rod to pass through without contact,
A projection that forms an insulation state is provided between at least one of the inner peripheral surface of the nozzle tip where the electrode rod is inserted and the outer peripheral surface of the part where the electrode rod is inserted. It is in.

[0007] The "nozzle tip" referred to in this specification
The term “is provided at the foremost portion of the plasma cutting torch and has an opening for ejecting a plasma arc generated from the electrode”. The nozzle tip is fixed with a shield cup via an insulator such as a baffle for insulating the electrode tip from the electrode rod. Further, there is a structure in which a gap is provided between an electrode bar and a support member which is externally fitted to and fixed to a holder, and is screwed and fixed.

The "electrode bar" is for generating a cutting current between the electrode bar and the base material. Zirconium (Z) is applied to the tip of the electrode bar body made of a conductive material such as copper.
r) or a special metal such as hafnium (Hf) embedded as an electrode member. The electrode rod is mounted on the torch main body and connected to the negative electrode of the plasma cutting device through the torch main body. The structure of the portion of the torch main body where the electrode rod is loaded is not particularly limited, but a structure having a function of cooling the electrode rod, which becomes extremely hot at the time of cutting, is preferable.

[0009] The "projecting body" refers to the inner peripheral surface of the nozzle tip,
A member provided to protrude from at least one of the outer peripheral surfaces of the electrode rod, and refers to a member for forming an insulating state. In other words, the protrusion is a member for maintaining an insulating state between the nozzle tip and the electrode rod inserted therethrough, and a part or all of the protrusion protrudes from one or both of the nozzle tip and the electrode rod. It is provided in the state where it was set.
As means for providing this, a method such as sticking, winding, coating with an adhesive, fitting into a groove or a concave portion, or embedding a part of the hole into a through hole is used. The fixing means is, for example, adhesion, adhesion, caulking, screwing, or tightening. The shape of the protruding body is, for example, a ring shape, a small lump such as a sphere, a thread, a string,
It has a sheet shape or the like.

[0010] The material of the projection may be ceramic, heat-resistant rubber, plastic, heat-resistant fiber, or the like, or may be a conductive member or a surface coated with an insulator. In short, what is necessary is just to intervene in the gap between the nozzle tip and the electrode rod so as to maintain the separated state without causing a short circuit between them. However, since the gap between the nozzle tip and the electrode rod forms a flow path for the working gas, if the projection has a shape such as a ring that closes between them, at least one space is required to secure this flow path. It is necessary to provide a penetrating part in the part. For this reason, when the projecting body has a ring shape or the like, by providing a plurality of penetrating portions oblique to the axial direction on the outer peripheral surface or the inner peripheral surface thereof, it is used as a so-called gas distributor that generates a swirling flow in the working gas. be able to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments of the invention shown in the drawings.

FIG. 1 shows a plasma cutting torch 1 according to the present invention.
In this embodiment, a peripheral groove 3 is provided on an outer peripheral surface of a tip portion of an electrode rod 2 inserted into a nozzle tip 5,
A ring-shaped protrusion 4 made of silicone rubber is fitted into the circumferential groove 3 and fixed. Torch 1 shown in this example
Is a long nozzle tip 5 having a length of 40 mm. The electrode rod 2 is inserted through the nozzle tip 5 to the vicinity of the tip of the nozzle tip. Therefore, by providing the projection 4 at the tip of the electrode rod 2, a gap between the electrode rod 2 and the nozzle tip 5 can be ensured, and a short circuit between them can be reliably prevented. It becomes possible.

The projecting body 4 is formed in a ring shape as shown in FIGS. 2A and 2B, and a plurality of grooves 6 are provided on an outer peripheral surface thereof to secure a flow path of a working gas. Since the grooves 6 are provided obliquely to the axial direction as shown in the figure, when the working gas passes therethrough, they form a swirling flow, and a sharp cut surface can be obtained without the plasma arc spreading. Of course, if the protrusion 4 is provided on the inner peripheral surface side of the nose tip 5, the groove 6 is provided on the inner peripheral surface side of the protrusion 4.

FIG. 3 shows another example of the embodiment of the plasma cutting torch 1 according to the present invention, wherein three ceramic spheres are provided around the electrode rod 2 as the projections 4. This sphere has a diameter of 1.5 mm, and is fitted into a hemispherical concave portion 7 provided on the outer peripheral surface of the electrode rod 2 and fixed by hitting and caulking a part of the periphery. In the case of a small massive projection 4 such as a ceramic sphere, in addition to being fitted into a groove or a recess, a through hole 8 is provided on the peripheral surface of the nozzle tip 5 as shown in FIG. The protrusion 4 may be inserted so that the portion protrudes. Through hole 8
Is sealed and fixed by welding or the like.

In the case where the ring-shaped projection 4 is formed of a member having a low elastic coefficient such as a ceramic material, FIG.
As shown in (a), the ring may be formed into a shape divided into two parts, fitted into the peripheral groove 3, and then swaged by hitting the edge of the peripheral groove 3. Further, as shown in FIG. 2B, a divided structure in which the electrode rods 2 are screwed and connected may be adopted, and the ring-shaped projection 4 may be sandwiched and fixed.

[0016]

As described above, the plasma cutting torch according to the present invention is a plasma cutting torch having a structure in which a part of an electrode rod is inserted into a nozzle tip for ejecting plasma gas without contacting a part of the electrode rod. A protrusion for forming an insulating state is provided between at least one of the inner peripheral surface of the nozzle tip at the portion where the electrode rod is inserted and the outer peripheral surface of the portion at which the electrode rod is inserted. Accordingly, even if the shield cup is insufficiently tightened or loosened during the operation, a short circuit between the electrode rod and the nozzle tip can be prevented, so that the generation of plasma is always kept constant and the operation can be stabilized. .

Further, since the longer the electrode rod and the nozzle tip become, the longer the electrode rod and the nozzle tip are liable to burn, it has conventionally been impossible to use a long electrode rod and a nozzle tip. However, in the plasma cutting torch according to the present invention, Even when the nozzle tip is lengthened to increase visibility or perform fine cutting, contact between the electrode rod and the nozzle tip can be reliably prevented, and short-circuiting does not occur even if the electrode rod is displaced. In addition, since the center position of the electrode rod is constant, the cut surface is clean and there is an effect that the inside of the nozzle tip, the ejection hole, the tip portion, and the like can be prevented from being burned. From these facts, it is possible to promote the lengthening of the nozzle tip, which could not be achieved conventionally, without any problem.

[Brief description of the drawings]

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

2A is a plan view of the protrusion shown in FIG. 1, and FIG. 2B is a side view thereof.

FIG. 3 is a schematic sectional view showing another example of the embodiment of the plasma cutting torch according to the present invention.

FIG. 4 is a schematic sectional view showing still another example of the embodiment of the plasma cutting torch according to the present invention.

5 (a) and 5 (b) are exploded perspective views showing still another example of the embodiment of the plasma cutting torch according to the present invention.

FIGS. 6A and 6B are schematic cross-sectional views each showing an example of a conventional plasma cutting torch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma cutting torch 2 Electrode rod 3 Peripheral groove 4 Projection 5 Nozzle tip 6 Groove 7 Depression 8 Through hole

Claims (3)

[Claims] 1. A torch for plasma cutting having a structure in which a part of an electrode rod is inserted into a nozzle tip for ejecting plasma gas without contacting the part of the electrode rod. A plasma cutting torch characterized in that a projection for forming an insulating state is provided between at least one of an outer peripheral surface of a peripheral surface and an outer peripheral surface of a portion where the electrode rod is inserted. 2. The projecting body according to claim 1, wherein the projecting body has a ring shape, and a plurality of working gas flow paths communicating with the axial direction are provided in one of an inner peripheral portion and an outer peripheral portion. Plasma cutting torch. 3. The projecting body is in the form of a small lump, and is partially embedded in at least one of the inner peripheral surface of the nozzle tip and the outer peripheral surface of the electrode rod. Plasma cutting torch.