JPH08294779A - Plasma torch nozzle - Google Patents

Abstract

(57) [Abstract] [Purpose] By covering the nozzle with a cap, spatter generated during processing is prevented from welding to the nozzle. Costs are reduced by replacing the smallest unit parts when spatter damages the cap. When a plasma arc formed by electrical discharge between an electrode 3 and a work material is jetted from an orifice 7a formed in a nozzle 7 for processing, the orifice is opposed to the orifice 7a formed in the nozzle 7 A cover member 8 which is formed with a hole 8a slightly larger than 7a and which is disposed in close contact with the tip cylinder upper portion 7b of the nozzle 7 and the tapered portion 7e is detachably fixed to the cassette A by a cap body 12. At least the contact surface of the cover member 8 with the nozzle or the contact surface of the nozzle 7 with the cover member 8 is subjected to an insulation treatment in which ceramic and tetrafluoroethylene resin are overlaid and coated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents a spatter from adhering to a nozzle by covering a nozzle with a cap, and when spatter adheres to a cap, a minimum unit or cover member can be replaced. The present invention relates to a plasma torch configured as described above.

[0002]

2. Description of the Related Art In a plasma torch for cutting or welding a material to be processed, a negative potential is applied to an electrode and a positive potential is applied to a nozzle to cause a discharge between the two, thereby forming a pilot arc to form a nozzle orifice. To the outside, and then a positive potential is applied to the material to be processed to cause a discharge between the material and the electrode to form a plasma arc that contributes to the processing.

A general plasma torch, for example, as shown in the tip portion of the plasma torch in FIG. 3, is provided with a nozzle having an orifice formed opposite to an electrode for passing a plasma arc, and the torch body is covered with a cap. The cooling water is circulated in a space defined by the torch body and the cap. In such a plasma torch, the tip of the nozzle is arranged so as to face the workpiece and is exposed to the outside.

Most recent plasma torches, especially plasma torches for cutting a workpiece, are mainly configured to form a secondary gas flow around the plasma arc. This plasma torch has a first nozzle facing the electrode and having a first orifice for passing a plasma arc, and a second orifice for passing the plasma arc and a secondary gas outside the first nozzle. It is configured to include the formed second nozzle.

In the plasma torch as described above, for example, in the technique disclosed in Japanese Patent Publication No. 2-504603, a nozzle having a nozzle orifice and a shield having an outlet orifice are provided, and the shield is exposed facing a workpiece. It is arranged in a closed state.

[0006]

When a conventional plasma torch is used to perform processing such as welding or cutting on a material to be processed, spatter of molten metal or oxidation product is generated along with the processing. Scatter. Since the nozzle is formed of a metal having conductivity, a part of the scattered spatter is welded to the exposed portion of the nozzle to damage it. In addition, if the spatter deposited on the nozzle increases as the processing time increases, the deposited spatter comes into contact with the work material, the nozzle becomes the same potential as the work material, and a double arc occurs, causing the nozzle to sharply increase. Processing may be interrupted due to melting. Therefore, there is a problem that the exposed portion of the nozzle must be cleaned or the nozzle must be replaced regularly.

According to the technique disclosed in the above Japanese Patent Publication No. 2-504603, the double arc can be prevented by electrically insulating the nozzle and the shield. However, even with this technique It is not possible to prevent welding or adhesion of spatter to the shield, and it becomes necessary to replace the shield as the processing time increases.

The nozzle is required to be processed with high accuracy in terms of the size of the orifice, the forming position, the outer diameter, and the like. For this reason, it becomes inevitably expensive, and if the replacement frequency is high, the processing cost increases.

An object of the present invention is to prevent the spatter generated by processing by welding the nozzle by covering the nozzle with a cap, and to prevent the spatter from damaging the cap, and to provide a minimum unit cover member when the spatter damages the cap. It is to provide a plasma torch that can be reduced in cost by replacing it.

[0010]

In order to solve the above-mentioned problems, a plasma torch according to the present invention uses a plasma arc formed by an electric discharge between an electrode and a workpiece to form a workpiece from an orifice formed in a nozzle. In a plasma torch that is jetted toward and processed, a hole that is slightly larger than the orifice that is formed facing the orifice formed in the nozzle is formed, and a cover member is set at the tip of the nozzle and fixed to the torch body. The cap is provided.

In the above plasma torch, it is preferable that the cap is composed of a cover member formed of a metal material and set corresponding to the nozzle, and a cap body to which the cover member is detachably attached.

It is preferable to disconnect the cover member from the electric potential of the nozzle. Therefore, the cover member itself is made of a ceramic material, or a cover member made of a metal material is at least the contact surface with the nozzle or the nozzle cover. Insulation is applied to the contact surface with the village. It is desirable that the insulating treatment be performed by coating ceramic and tetrafluoroethylene resin in layers.

[0013]

In the above plasma torch, a cover member having a hole slightly larger than the orifice set facing the orifice formed in the nozzle is used, and the cover member is brought into close contact with the tip portion of the nozzle, and the close contact is made. Since the cover member, which has been swaged, is fixed to the torch body by the cap body, the cap can cover substantially the entire nozzle. For this reason, there is no possibility that spatter generated by processing will be welded to the nozzle, and the nozzle will not be damaged.

Further, since the spatter scattered from the processed portion is rapidly cooled by the atmosphere, even if the spatter scattered over a long distance adheres to a metal having a relatively low melting temperature, it does not dissolve the metal but simply adheres to it. Stop to do it. Such spatter is easily peeled off from the adhered portion by cleaning, and the adhered metal portion is not damaged.

Therefore, by forming a cap with a cover member which is made of a metal material and is set corresponding to the nozzle, and a cap body to which the cover member is detachably attached, a damaged portion due to spatter is prevented. It is possible to stop on the cover member. Then, when the damage of the cover member grows, only the cover member is replaced, so that the replacement parts associated with the damage can be minimized. Therefore, it is possible to reduce the cost required for processing including the cost of the replacement part as much as possible.

The cover member is formed of ceramic, or the contact surface with the nozzle or the entire surface is subjected to insulation treatment,
For example, the cover member and the nozzle can be electrically insulated by interposing an insulating sleeve between the cap body and the torch body or by subjecting the contact surface of the cap body with the cover member to an insulating treatment. Therefore, even if the cover member directly or indirectly comes into contact with the workpiece, the nozzle does not have the same potential as the workpiece, and the occurrence of double arc can be prevented.

Further, by applying a composite coating in which ceramic and tetrafluoroethylene resin are laminated, the surface of the coating layer can be smoothed and the cover member and the nozzle can be adhered in good condition. Can be done. Further, even if spatter adheres to the insulation-treated surface, the thermal shock due to spatter is relaxed and the ceramic layer does not peel off.

An embodiment of the plasma torch will be described below with reference to the drawings. FIG. 1 is a diagram for explaining the configuration of the tip portion of the plasma torch of the present invention. FIG. 2 is a cross-sectional view illustrating the configurations of the nozzle and the cover member. 3 is a diagram illustrating the configuration of the tip portion of a general plasma torch.

The plasma torch according to the present invention is constructed so that the nozzle is covered with a cap to prevent the spatter from adhering to the nozzle, and to limit the damaged portion due to the spatter so that the smallest unit can be replaced. The processing cost is reduced as much as possible.

A specific configuration of the tip portion of the plasma torch will be described. In FIG. 1, the mounting pipe 1 is connected to the cathode of the power source through an electrode base and a distribution member (not shown).

A cooling pipe 2 arranged inside a mounting pipe 1 having conductivity is fixed. When the electrode 3 is attached to the tip of the attachment pipe 1, a cooling water passage 4 is formed inside the pipe 1.

An insulating pipe 5 having an insulating property is arranged at a predetermined distance from the outer periphery of the mounting pipe 1. One end of this insulating pipe 5 is fitted into a ring-shaped groove formed by an electrode base and a water channel member (not shown), and the other end is a device head 6
It is integrally attached to the cassette A by engaging with the step portion 6a formed on the inner periphery of the. The space formed between the insulating pipe 5 and the mounting pipe 1 has a function as a plasma gas passage 13.

The device head 6 has a function of attaching the nozzle 7 and the cap B and attaching these members to the torch body.

A screw 1a is formed at the tip of the mounting pipe 1 constituting the cassette A. An electrode 3 having an electrode 3a embedded in the center thereof is detachably attached to the screw 1a.

The inside of the nozzle 7 is formed in a funnel shape as a whole, and forms an orifice 7a for passing a plasma arc and a plasma gas stream, and a body portion 7b on the outer peripheral surface.
A seal portion 7c, a tubular portion 7d, and a taper portion 7e are formed. An O-ring groove 9 is formed in the seal portion 7c, and a nozzle step portion 10 is formed in the base portion of the tubular portion 7d. The body portion 7b is fitted in a fitting hole 6b formed in the device head 6. Therefore, the body portion 7b and the fitting portion 6b are formed with a predetermined fitting tolerance.

The tubular portion 7d of the nozzle 7 has an opening 8a slightly larger than the nozzle orifice 7a, and a cover member 8 insulated from the potential of the nozzle 7 is fitted into the tubular portion 7d of the nozzle 7. .

FIG. 2 (a) shows the tip cylindrical portion 7d of the nozzle 7.
The cover member 8 insulated from the potential of the nozzle 7 is fitted through the O-ring groove.

FIG. 2B shows the tip cylindrical portion 7d of the nozzle 7.
A cover member 8 that is threaded into a shell and insulated from the nozzle potential
Are those which are screwed and closely attached by screws.

FIG. 2 (c) shows that the cylindrical portion 7d and the tapered portion 7e of the nozzle 7 are fitted and closely contacted with each other due to the fitting tolerance of the inner diameter of the cover member 8 insulated from the nozzle potential and the tapered portion.

FIG. 2D shows the tip cylindrical portion 7 of the nozzle 7.
In d and the nozzle step portion 10, the inner processing of the cover member 8 insulated from the nozzle potential is work-bonded within the bonding tolerance.

In the nozzle 7 constructed as described above, in FIG. 1, a centering stone 11 having an insulating property is arranged on the electrode 3 attached to the attachment pipe 1, and the centering stone 11 is inserted into the inside of the nozzle 7. In this state, the cassette A is attached by the cover member 8 and the cap body 12.

The centering stone 11 is interposed between the electrode 3 and the nozzle 7 to electrically insulate the both, and
It has a function of swirling the plasma gas flowing through the plasma gas passage 13 and supplying it to the periphery of the electrode 3.

The cap body 12 does not have to be electrically conductive. However, the radiant heat accompanying the plasma processing acts on the cap body 12 to raise its temperature, and the cap body 12 is screwed into the screw 6c formed on the device head 6 at the end portion on the inner peripheral surface and on the side of the cassette A. The screw 12a is formed by using a metal material.

The entire cap body 12 is formed in a funnel shape, and a hole 12b into which the cover member 8 is fitted is formed at the tip end side.
And a flange-shaped locking portion 12c is formed around the hole 12b.

The entire cover member 8 is formed to have a taper, and the outer peripheral surface thereof has a body portion 8b fitted into the hole 12b of the cap body 12, and a taper portion 8 continuous from the body portion 8b to the tip side.
c, a flange portion 8d formed on the opposite side of the tapered portion 8c of the body portion 8b is formed. Further, a hole 8a having a size slightly larger than the orifice 7a of the nozzle 7 is formed on the tip surface of the taper portion 8c. Further, the body portion 8b
An O-ring groove 8e is formed in the.

The outer diameter of the body portion 8b is slightly smaller than the hole 12b of the cap body 12. Further, the flange portion 8d engages with the locking portion 12c formed on the cap body 12 at the end face on the body portion 8b side, and the cap body 12 is screwed by the screw 1
It is screwed with the screw portion 6c of the device head 6 by 2a.

When the cover member 8 is screwed into the cassette A in the cap body 12, the cover member 8 in close contact with the nozzle 7 has a function of exerting a pressing force on the nozzle 7.

The cover member 8 is attached to the hole 12b of the cap body 12.
When fitted to, the locking portion 12c engages with the flange portion 8d of the cover member 8. When the nozzle 7 is fitted into the cap B in which the cover member 8 is fitted into the cap body 12, the flange portion 8d of the cover member 8 comes into contact with the outer nozzle tubular portion 7d and the taper portion 7e. Therefore, by screwing the cap B onto the cassette A, it is possible to mount the nozzle 7 on the cassette A and cover substantially the entire surface of the nozzle 7.

In the plasma torch constructed as described above, the electrode 3 is fixed to the mounting pipe 1 constituting the cassette A, the centering stone 11 is fitted to the electrode 3, and the nozzle 7 is fitted into the fitting hole of the machine head 6. Even when the mounting pipe 1 is displaced from the axial center of the plasma torch when mounted on 6 b, the outer peripheral body portion 7 b forming the nozzle 7 is fitted into the fitting hole 6 b of the device head 6. According to the correction, the centering stone 11 comes into contact with the electrode 3 to correct the blurring of the mounting pipe 1, and according to this correction, the coaxiality between the electrode 3 and the orifice 7a formed in the nozzle 7 can be guaranteed.

Then, the cap body 12 is screwed into the screw 6c formed on the device head 6, whereby the nozzle 7 is attached to the cassette A by these members and the cooling water passage 4a is formed.
And it is possible to cover substantially the entire surface of the nozzle 7 with the cap B.

In the above plasma torch, the cover member 8 constituting the cap B is formed to have a size substantially equal to or slightly larger than the tip end portion of the nozzle 7, and is detachably attached to the cap body 12. . Therefore, spatters scattered during processing are mainly welded to the cover member 8, and spatters scattered to the cap body 12 are in a state of being cooled by the atmosphere.

Therefore, it is possible to prevent the cover member 8 from being damaged by the spatter. If the cover member 8 currently attached to the nozzle 7 is damaged, the cap body 12 can be removed from the cassette A and the damaged cover member 8 can be replaced with a new cover member 8. That is, when the plasma torch is damaged by spatter, the cover member 8 can be replaced as the minimum unit component.

In this embodiment, at least the contact surface of the cover member 8 constituting the cap B with respect to the nozzle 7 or the contact surface of the nozzle with respect to the cover member 8 is subjected to an insulation treatment of a ceramic layer and a tetrafluoroethylene resin layer, and As shown in FIG. 1, an insulating sleeve 14 is interposed between the cap body 12 and the device head 6, or the cover member 8 is used.
The cap B is electrically insulated from the nozzle 7 by applying an insulating treatment of a ceramic layer and a tetrafluoroethylene resin layer to the contact surface of the nozzle 7 and the contact surface of the cap body 12.

By selectively adopting the above method to electrically insulate the cap B from the nozzle 7, even if the cover member 8 directly or indirectly contacts the workpiece,
The nozzle 7 does not have the same potential as the work material, and therefore it is possible to prevent the double arc from occurring.

In particular, when the cap B is screwed into the cassette A and the cover member 8 is brought into pressure contact with the nozzle 7, it is preferable that the contact surfaces of the both are made smooth and over the entire surface. That is, when the cover member 8 and the nozzle 7 do not evenly contact with each other, a difference in surface pressure occurs, which causes distortion in any member, and there is a possibility that the processing performance cannot be maintained.

However, in the coating layer composed of the ceramic layer and the tetrafluoroethylene resin layer, even if irregularities are formed on the surface of the ceramic layer by thermal spraying, the irregularities are filled with the tetrafluoroethylene resin layer to form a smooth surface. It is possible to Therefore, by forming a coating layer made of a ceramic layer and a tetrafluoroethylene resin layer on the contact surface of the cover member 8 with respect to the nozzle 7, it is possible to make uniform contact.

As described above, at least the contact surface of the cover member 8 with the nozzle 7 or the contact surface of the nozzle 7 with the cover member 8 is coated with an insulating coating layer composed of a ceramic layer and a tetrafluoroethylene resin layer. At the same time, by interposing an insulating sleeve 14 between the cap body 12 and the device head 6, or by forming the coating layer on the contact surface between the cover member 8 and the nozzle 7 and the contact surface with the cap body 12, Even if the cover member 8 is insulated from the nozzle 7 and the cover member 8 directly or indirectly contacts the workpiece, it is possible to prevent the double arc from occurring.

[0048]

As described above in detail, in the plasma torch according to the present invention, by covering the nozzle with the cap, it is possible to prevent the spatter generated during processing from welding to the nozzle. Therefore, the nozzle is not damaged by the spatter, and the nozzle replacement frequency can be reduced.

Further, the cover member is detachably attached to the nozzle, and the cap body is removed by a screw to stop the portion damaged by spatter on the cover member and replace it when the cover member is damaged. By doing so, the replacement part can be the minimum unit. Therefore, it is possible to reduce the cost of the replacement part and the processing cost as much as possible.

By electrically insulating the cover member constituting the cap from the nozzle, the nozzle does not have the same potential as the workpiece even if the cover member directly or indirectly contacts the workpiece. . Therefore, it has a feature that the occurrence of a double arc can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of a tip portion of a plasma torch of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a nozzle and a cover member. (A), (b) is explanatory drawing of the Example which forms a cover member in close contact with a nozzle. (C), (d) is explanatory drawing of the Example which fits and forms a cover member to a nozzle.

FIG. 3 is a diagram illustrating a configuration of a tip portion of a general plasma torch. It is sectional drawing explaining the structure of a cap.

[Explanation of symbols]

A cassette B cap 1 mounting pipe 2 cooling pipe 3 electrode 4 cooling water passage 5 insulating pipe 6 device head 7 nozzle 8 cover member 9 O-ring groove 10 nozzle step 11 centering stone 12 cap body 13 plasma gas passage 14 insulating sleeve

Claims (6)

[Claims] 1. A cover member insulated from a nozzle potential at a nozzle tip of a plasma torch for processing a plasma arc formed by discharging an electric discharge between an electrode and a work material from an orifice toward the work material. The nozzle of the plasma torch, wherein the cover member is detachably attached to the nozzle through an O-ring. 2. A cover member insulated from the nozzle potential at the nozzle tip of a plasma torch for processing a plasma arc formed by discharging an electric discharge between an electrode and a work material from an orifice toward the work material. A nozzle of a plasma torch, characterized in that a cover member is detachably attached to the nozzle by screwing. 3. A cover member insulated from a nozzle potential at a nozzle tip of a plasma torch for processing a plasma arc formed by discharging an electric discharge between an electrode and a work material from an orifice toward the work material. A nozzle of a plasma torch, characterized in that a cover member is fixedly attached to the nozzle by fitting. 4. A cover member insulated from a nozzle potential at a nozzle tip of a plasma torch for processing a plasma arc formed by discharging an electric discharge between an electrode and a material to be processed from an orifice toward a material to be processed. The nozzle of the plasma torch, wherein the cover member is fixed to the nozzle by adhesion. 5. The cover member insulated from the nozzle potential is made of a metal material, and at least the contact surface of the nozzle or the contact surface of the nozzle with the cover member is coated with ceramic and fluorinated ethylene resin. The nozzle of the plasma torch according to claim 1, 2, 3, or 4. 6. A ceramic-made cover member is provided at the nozzle tip of a plasma torch for processing a plasma arc formed by discharging an electric discharge between an electrode and a work material from an orifice toward the work material. The nozzle of the plasma torch, wherein the cover member is fixed to the nozzle by brazing.