JPH07282996A - Plasma torch - Google Patents

Abstract

PURPOSE:To prevent sputters generated associated with the plasma torch processing from fusion attachment to a nozzle by covering it with a cap; to reduce the costs by replacing minimum amount of components when the cap is damaged by sputters. CONSTITUTION:Plasma arcs generated by electric discharge between an electrode 20 and a work to be processed are spouted out of orifices 21, 23 formed in a nozzle C, wherein a cap D is provided which is secured to a torch body in touch with a tapered portion 24c formed at the tip of the nozzle C where a hole 32d some greater than the orifice 23 is formed while confronting the orifice 23 formed in the nozzle C. The cap D is composed of a covering member 32 positioned as mating with the nozzle C and a cap body 31 to which the covering member 32 is mounted removably. At least the contact surface of the covering member 32 with the nozzle C or the contact surface of the outer nozzle member 24 with the covering member 32 are coated with a ceramic material and ethylene tetrafluoride resin so that electrical insulation is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is constructed so that a nozzle is covered with a cap to prevent spatter from adhering to the nozzle, and when spatter adheres to the cap, the smallest unit can be replaced. It concerns plasma torches.

[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.

In a general plasma torch, a nozzle having an orifice for passing a plasma arc is arranged facing the electrode. The nozzle is attached to the torch body by a cap and is composed of the torch body and the cap. It is configured to allow cooling water to flow through the space. 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, 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 faces a workpiece. It is exposed.

[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.

The object of the present invention is to prevent the spatter generated by the processing from welding to the nozzle by covering the nozzle with the cap, and to replace the smallest unit parts when the spatter damages the cap. Therefore, it is to provide a plasma torch that can reduce the cost.

[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 for jetting and processing toward a nozzle, a cap that is opposed to an orifice formed in a nozzle, is slightly larger than the orifice, and is fixed to the torch body in contact with the tip of the nozzle. 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 arranged corresponding to the nozzle, and a cap body to which the cover member is detachably attached.

It is preferable that at least the contact surface of the cover member with the nozzle or the contact surface of the nozzle with the cover member is subjected to an insulation treatment to insulate the cover member from the potential of the nozzle. It is preferable that ethylene resin is coated on top of each other.

[0013]

In the above plasma torch, a cap having a hole slightly larger than the orifice formed facing the orifice formed in the nozzle is used, and the cap is brought into contact with the tip of the nozzle and fixed to the torch body. The cap can cover almost 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 melt 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 formed of a metal material and arranged corresponding to the nozzle, and a cap main 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 unit associated with the damage can be the minimum unit. Therefore, it is possible to reduce the cost required for processing including the cost of the replacement part as much as possible.

Further, the contact surface of the cover member with the nozzle or the contact surface of the nozzle with the cover member is subjected to an insulation treatment, and an insulating sleeve is interposed between the cap body and the torch body, or the cap of the cover member is capped. The cover member and the nozzle can be electrically insulated by subjecting the contact surface with the main body to the 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 the ceramic and the tetrafluoroethylene resin are laminated as the insulating treatment, the surface of the coating layer can be made smooth, and the cover member and the nozzle can be brought into contact with each other in a 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.

[0018]

EXAMPLES Examples of the plasma torch will be described below with reference to the drawings. FIG. 1 is a sectional view for explaining the overall configuration of the plasma torch, FIG. 2 is a diagram for explaining the configuration of the tip portion of the plasma torch, and FIG. 3 is a sectional view for explaining the configuration of the cap.

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

A specific configuration of the plasma torch will be described. In the figure, the plasma torch is a torch body A
A cassette B that is detachably attached to the tip of the torch body A, and a cap D that attaches the nozzle C to the tip of the cassette B and covers the nozzle C.

The torch body A is a tubular body 1 made of an insulating cloth-filled bakelite, and the tip side of the tubular body 1 (see FIG. 1).
And a joint body 2 made of a resin mold having an insulating property, which is fixed to the left side in FIG.
And the joint body 2 and the tip of which is exposed from the cylindrical body 1 and the screw 4a is formed on the exposed portion of the conductive member 4, and the cassette B which is arranged at the tip of the joint body 2.
A distribution member 5 having a plurality of holes 5a for distributing cooling water or gas by fitting distribution projections 11a formed on the electrode base 11 provided on the fixing member 6 and a fixing member 6 for fixing the distribution member 5 to the joint body 2. It is composed of and.

A plurality of holes 5a formed in the distributing member 5 are independently provided with a cooling water supply pipe 7 and a cooling water discharge pipe (not shown), a plasma gas supply pipe, and A pipe such as a supply pipe for the next gas is connected.
The distribution member 5 is connected to a cathode of a power source (not shown).

In the cassette B, an electrode base 11 having conductivity is arranged on the side of the torch body A. A water channel member 12 having an insulating property is fixed to the electrode base 11 by a screw 13a, and the water channel member 12 is electrically conductive. A device head 14 having a screw is fixed by a screw 13b. Therefore, the electrode base 11 and the device head 14 are electrically insulated.

On the side of the torch body A of the electrode base 11, a plurality of distribution protrusions corresponding to the plurality of holes 5a formed in the distribution member 5.
11a is formed. The distribution projections 11a are fitted into holes 5a connected to a cooling water supply pipe, a discharge pipe, a flange gas supply pipe, and a secondary gas supply pipe, respectively, and electrode the respective fluids.
It is configured so that it can supply to the periphery of 20, the nozzle C, and the cap D.

On the tip side of the electrode base 11, there is a mounting pipe 15 which is electrically conductive in conformity with the axis of the electrode base 11 and which mounts the electrode 20 on the tip, and a cooling pipe arranged inside the mounting pipe 15. 16 is stuck. When the electrode 20 is attached to the tip of the attachment pipe 15, a cooling water passage 51 is formed inside the pipe 15.

An insulating pipe 17 having an insulating property is arranged at a predetermined distance from the outer periphery of the mounting pipe 15. One end of this insulating pipe 17 is fitted into the ring-shaped groove 18 formed by the electrode base 11 and the water channel member 12, and the other end is engaged with the stepped portion 14a formed on the inner circumference of the vessel head 14. And is integrally attached to the cassette B. In addition, the space formed between the insulating pipe 17 and the mounting pipe 15 has a function as a passage 52 through which the plasma gas flows.

The device head 14 has a function of attaching the nozzle C and the cap D and attaching these members to the torch body A. For this reason, a step portion 14b is formed on the outer periphery of the device head 14 on the side of the torch body A, and a screw 14 for screwing the insert cap 30 into a predetermined position is further formed.
c, a screw 14d for screwing a cap body 31 which is a main body member of the cap D is formed. Further, a fitting hole 14e having a predetermined tolerance with the outer diameter of the inner nozzle member 22 constituting the nozzle C is formed on the inner circumference of the tip.

The cassette nut 19 has the electrode base 11, the water channel member 12, the device head 14, the mounting pipe 15, the cooling pipe 16 and the insulating pipe 17 which are integrally formed, mounted on the torch body A, and the conductive member 4 and the device head. 14 has a function of electrically connecting. Therefore, the cassette nut 19 is made of a conductive metal.

A screw 19a is formed on the inner circumference of the torch body A side of the cassette nut 19, and a hole into which the device head 14 is fitted and a flange-shaped locking portion 19b are formed at the other end. .
Then, the device head 14 is fitted into the hole, the engaging portion 19b is engaged with the step portion 14b of the device head 14, and the screw 19a is screwed onto the screw 4a of the conductive member 4 provided on the torch body A. , Cassette B
Is attached to the torch body A.

A screw 15a is formed at the tip of the mounting pipe 15 which constitutes the cassette B. An electrode 20 having an electrode material 20a embedded in the center thereof is detachably attached to the screw 15a.

The nozzle C includes an inner nozzle member 22 having a first orifice 21 for passing a plasma arc and a second orifice 23 for passing a plasma arc and a secondary air flow.
The outer nozzle member 24 is formed by integrally forming the inner nozzle member 22 and the outer nozzle member 24 by directly contacting each other.

The nozzle C has a function of arc discharge between itself and the electrode 20 at the start of processing to form a pilot arc. Therefore, the inner nozzle member 22, which constitutes the nozzle C,
The outer nozzle members 24 are each made of a conductive metal.

The inner nozzle member 22 is formed in a funnel shape as a whole, and a body portion 22a, a seal portion 22b, a cylindrical portion 22c, and a taper portion 22d are formed on the outer peripheral surface. Seal part 22
An O-ring groove 25 is formed in b, and the cylindrical portion 22c
A step portion 26 is formed at the base of the. The body portion 22a is fitted into a fitting hole 14e formed in the device head 14. Therefore, the body 22
The a and the fitting hole 14e are formed with a predetermined fitting tolerance. The first orifice 21 is formed in the tubular portion 22c.

The outer nozzle member 24 is formed in a cup shape as a whole, and a body portion 24a, a cylindrical portion 24b and a taper portion 24c are formed on the outer peripheral surface thereof, and an end surface of the body portion 24a is formed as a locking portion 27. Has been done. Further, the body portion 24a is formed with a plurality of holes 28 for allowing the secondary gas to flow therethrough.

The outer nozzle member 24 is formed integrally with the inner nozzle member 22. That is, the outer diameter of the stepped portion 26 of the inner nozzle member 22 is formed with a tolerance of a tight fit or a tight fit with respect to the inner diameter of the outer nozzle member 24, and then the inner nozzle member 22 is press-fitted into the outer nozzle member 24. The two have been integrated together.

Therefore, the coaxiality of the first orifice 21 formed in the inner nozzle member 22 and the second orifice 23 formed in the outer nozzle member 24 is determined according to the processing accuracy of the respective members 22, 24. Therefore, there is no change due to the replacement work of the electrode 20 and the attachment / detachment work of the nozzle C accompanying this work. That is, it is possible to guarantee the coaxiality of the first orifice 21 and the second orifice 23 regardless of the number of times the nozzle C is attached to and detached from the cassette B (torch body A).

When the inner nozzle member 22 and the outer nozzle member 24 are integrated, a secondary portion is formed between the outer peripheral surface of the cylindrical portion 22c and the tapered portion 22d of the inner nozzle member 22 and the inner peripheral surface of the outer nozzle member 24. A passage 53 through which gas flows is formed.

In the nozzle C constructed as described above, a centering stone 29 having an insulating property is arranged on the electrode 20 attached to the attachment pipe 15, and the stone 29 is attached to the inner nozzle member.
The cassette B is inserted into the cassette B with the insert cap 30 and the cap D inserted therein.

The centering stone 29 is interposed between the electrode 20 and the nozzle C to electrically insulate them from each other, and has a function of swirling the plasma gas flowing through the passage 52 and supplying it to the periphery of the electrode 20.

The insert cap 30 is a cap D and a device head
14 has a function of dividing a space constituted by 14 into a cooling water passage 54 and a secondary gas passage 55, and a cap 14 at the end of the inner periphery of the cap 30 on the cassette B side. A screw 30a is formed to be screwed with the screw 14c formed on the inner surface of the inner nozzle member 22, and an engaging portion 30b for engaging with a step portion 26 formed on the inner nozzle member 22 of the nozzle C is formed at the tip end. ing. The nozzle C is attached to the cassette B by engaging the stepped portion 26 of the nozzle C with the engagement portion 30b and screwing the stepped portion 26 into the device head 14.

The cap D is screwed onto the device head 14 to mount the nozzle C on the cassette B and to cover the nozzle C like a cover, and between the device head 14 and the insert cap 30, a passage 55 for the secondary gas is provided. Has the function of forming

The cap D is constructed so as to be detachable by fitting it to the cap body 31 and the cap body 31, and when the cap D is screwed onto the device head 14 of the cassette B, the outer nozzle constituting the nozzle C is formed. The cover member 32 is in contact with the tapered portion 24c of the member 24.

The cap body 31 does not need to have conductivity. However, the radiant heat accompanying the plasma processing acts on the cap body 31 to raise its temperature, and the cap body 31 is screwed with the screw 14d formed on the device head 14 at the end portion on the inner peripheral surface on the side of the cassette B. The screw 31a is formed by using a metal material.

The entire cap body 31 is formed in a funnel shape, and a hole 31b for fitting the cover member 32 is formed at the tip end side, and a flange-shaped locking portion 31c is formed around the hole 31b.
Are formed.

The cover member 32 is formed so as to have a taper as a whole, and has a body portion fitted on the outer peripheral surface with the hole 31b of the cap body 31.
32a, a tapered portion 32b continuous from the body portion 32a to the tip side, and a flange portion formed on the opposite side of the tapered portion 32b of the body portion 32a.
32c is formed. Further, a hole 32 having a size slightly larger than the second orifice 23 formed in the outer nozzle member 24 constituting the nozzle C is formed in the tip end surface of the tapered portion 32b.
d is formed. Further, the O-ring groove 33 is provided on the body 32a.
Are formed.

The outer diameter of the body portion 32a is substantially equal to or slightly larger than the outer diameter of the body portion 24a of the outer nozzle member 24. The flange portion 32c has an end surface on the body portion 32a side that engages with a locking portion 31c formed on the cap body 31, and the other end surface that abuts with a step portion 27 formed on the outer nozzle member 24 constituting the nozzle C. It is configured to be able to contact.

The cover member 32 covers the cap D with the cassette B.
The outer nozzle member 24 constituting the nozzle C when screwed into
It has a function of coming into contact with the tip portion of the nozzle and applying a pressing force to the nozzle C. Therefore, the inner peripheral surface 32e of the cover member 32
Is required to come into contact with at least the tip portion of the tapered portion 24c of the outer nozzle member 24. In this embodiment, the inner peripheral surface 32e of the cover member 32 has the cylindrical portion 24 of the outer nozzle member 24.
It is formed to have the same shape as b and the tapered portion 24c.

When the cover member 32 is fitted into the hole 31b of the cap body 31, the locking portion 31c engages with the flange portion 32c of the cover member 32. Further, when the nozzle C is fitted into the cap D in which the cover member 32 is fitted into the cap body 31, the flange portion 32c of the cover member 32 comes into contact with the step portion 27 of the outer nozzle member 24.
Therefore, by screwing the cap D onto the cassette B, the nozzle C is attached to the cassette B and the nozzle C
It is possible to cover almost the entire surface of.

In the plasma torch constructed as described above, the electrode 20 is fixed to the mounting pipe 15 constituting the cassette B, the centering stone 29 is fitted to the electrode 20, and the nozzle C is fitted into the fitting hole of the head 14. Even when the mounting pipe 15 is deviated from the axis of the plasma torch when mounted on 14e, the body portion 22a of the inner nozzle member 22 constituting the nozzle C is fitted into the fitting hole 14e of the device head 14. As it is fitted,
Centering stone 29 is in contact with electrode 20 and mounting pipe
The blurring of 15 is corrected, and the electrode 20 and the nozzle C are corrected with this correction.
It is possible to guarantee the coaxiality of the first orifice 21 and the second orifice 23 formed in the.

By screwing the insert cap 30 and the cap D into the screws 14c and 14d formed on the device head 14, the nozzle C is attached to the cassette B by these members and the cooling water passage 53 and the secondary gas are supplied. It is possible to form the passage 54 and to cover substantially the entire surface of the nozzle C with the cap D.

In the above plasma torch, the cover member 32 constituting the cap D is formed to have a size substantially equal to or slightly larger than that of the nozzle C, and is detachably attached to the cap body 31. Therefore, spatters scattered during processing are mainly welded to the cover member 32, and spatters scattered to the cap body 31 are in a state of being cooled by the atmosphere.

Therefore, the cover member is protected from damage due to spatter.
It is possible to stop at 32. And now cap body 31
If the cover member 32 attached to the device is damaged, the cap D can be removed from the cassette B and the damaged cover member 32 can be replaced with a new cover member 32. That is, when the plasma torch is damaged by spatter, the cover member 32 can be replaced as the minimum unit component.

In this embodiment, at least the contact surface of the cover member 32 constituting the cap D with respect to the outer nozzle member 24 constituting the nozzle C or the cover member of the outer nozzle member 24.
By providing an insulating treatment of a ceramic layer and a tetrafluoroethylene resin layer on the contact surface with respect to 32 and interposing an insulating sleeve 34 between the cap body 31 and the device head 14 as shown in FIG. Outside nozzle member of the cover member 32
The cap D is electrically insulated from the nozzle C by subjecting the contact surface with respect to 24 and the contact surface with respect to the cap body 31 to an insulating treatment of a ceramic layer and a tetrafluoroethylene resin layer.

By selectively adopting the method as described above to electrically insulate the cap D and the nozzle C, even if the cover member 32 comes into direct or indirect contact with the workpiece,
The nozzle C does not have the same potential as the material to be processed, and therefore it is possible to prevent the double arc from occurring.

In particular, when the cap D is screwed into the cassette B and the cover member 32 is brought into pressure contact with the outer nozzle member 24, it is preferable that the contact surfaces of both are made smooth and in contact with each other. That is, if the cover member 32 and the outer nozzle member 24 do not contact each other evenly, a difference in surface pressure may occur, causing distortion in one of the members, and it may be impossible to maintain the processing performance.

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, it is possible to make uniform contact by forming a coating layer made of a ceramic layer and a tetrafluoroethylene resin layer on the contact surface of the cover member 32 with respect to the outer nozzle member 24.

As described above, at least the contact surface of the cover member 32 with the outer nozzle member 24 or the contact surface of the outer nozzle member 24 with the cover member 32 has an insulating coating composed of a ceramic layer and a tetrafluoroethylene resin layer. An insulating sleeve 34 is formed between the cap body 31 and the device head 14 while forming a layer.
Or by forming the coating layer on the contact surface of the cover member 32 with the outer nozzle member 24 and the contact surface with the cap body 31, the cover member 32 is insulated from the nozzle C and the cover member 32 is removed. It is possible to prevent the double arc from being generated even when the workpiece is directly or indirectly contacted with the workpiece.

[0058]

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, by constructing the cap with the cover member and the cap body to which the cover member is detachably attached, the portion damaged by spatter is stopped on the cover member,
By replacing the cover member when it is damaged, the replacement part can be made the minimum unit. Therefore, it is possible to reduce the cost of the replacement part and the processing cost as much as possible.

Further, by electrically insulating the cover member constituting the cap from the nozzle, even if the cover member directly or indirectly contacts the workpiece, the nozzle does not have the same potential as 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 cross-sectional view illustrating the overall configuration of a plasma torch.

FIG. 2 is a diagram illustrating a configuration of a tip portion of a plasma torch.

FIG. 3 is a cross-sectional view illustrating the configuration of a cap.

[Explanation of symbols]

A torch body B
Cassette C Nozzle C D
Cap 1 Tube 2
Joint body 4 Conductive member 5
Distribution member 6 Fixed member 7
Supply tube 11 Electrode stand 12
Waterway member 14 Vessel head 15
Mounting pipe 16 Cooling pipe 17
Insulation pipe 19 Cassette nut 20
Electrode 21 1st orifice 22
Inner nozzle member 23 Second orifice 24
Outer nozzle member 26 Step 27
Locking part 28 Hole 29
Centering Stone 30 Insert Cap 31
Cap body 31b Hole 31c
Locking part 32 Cover member 32a
Body 32b Taper 32c
Flange 32d hole 32e
Inner peripheral surface 34 Insulation sleeve 51 to 55
aisle

Claims (4)

[Claims] 1. A plasma torch for processing a plasma arc by discharging a plasma arc formed between an electrode and a material to be processed from an orifice formed in the nozzle toward the material to be processed, and an orifice formed in the nozzle. A plasma torch which is provided with a cap which is opposed to the orifice and is slightly larger than the orifice, and which is in contact with the tip of the nozzle and fixed to the torch body. 2. The cap is composed of a cover member formed of a metal material and arranged corresponding to the nozzle, and a cap main body to which the cover member is detachably attached. The plasma torch according to claim 1, 3. The plasma according to claim 2, wherein at least a contact surface of the cover member with the nozzle or a contact surface of the nozzle with the cover member is subjected to an insulation treatment to insulate the cover member from the potential of the nozzle. torch. 4. The plasma torch according to claim 3, wherein the insulating treatment is performed by coating ceramic and tetrafluoroethylene resin in layers.