JP2018200857A - Nozzle for air plasma gouging - Google Patents

Abstract

To provide a nozzle for air plasma gouging that can achieve a long service life thereof and perform high-quality gouging.SOLUTION: The nozzle for air plasma gouging has an insulation part at an outer periphery of an end side of an opening of the nozzle and is configured to make the insulation part to have a following shape. This can configure the nozzle so that the insulation part made of heat-resistant resin with high heat-transfer performance is provided at the outer periphery of a nozzle conductive part on a surface which may contact a base material so as to avoid the nozzle from electrically contacting the base material unintentionally during gouging work, which can reduce damage of a gouging nozzle. Further, an inclined following part is provided in the insulation part, which allows the nozzle to follow the surface of the base material so as to reduce variations in quality of gouging performed by workers.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an air plasma gouging nozzle having an insulating portion on an outer peripheral portion, and a plasma cutting torch having the nozzle.

First, the configuration of the plasma arc cutting apparatus will be described.
In plasma cutting, the electrode is negative polarity, the nozzle is positive polarity,
A pilot arc is generated between the electrode and the nozzle, and then this arc is generated.

  This is supplied to the plasma cutting torch, and the cooling effect when the working gas, which is the gas that becomes the plasma arc, flows through the nozzle and mechanically squeezed by the nozzle hole at the tip of the nozzle to form a high-temperature plasma arc to melt the workpiece And it blows away and cuts.

  Conventionally, a plasma arc cutting device including a plasma cutting torch and a cutting power source is known (for example, see Patent Document 1).

FIG. 5 is a diagram showing a schematic configuration of a conventional plasma arc cutting apparatus.
In FIG. 5, the compressor 2 that compresses the working gas is connected to a regulator 3 installed inside the cutting power source 4 or outside the cutting power source 4. After adjusting the secondary pressure of the working gas to a constant value in the regulator 3, the working gas is guided from the regulator 3 into the cutting power source 4.
The regulator 3 is connected to a gas valve (not shown) that turns on and off the starting and stopping of the plasma arc provided inside the cutting power source 4, and the working gas flows inside the cutting power source 4.

This gas valve is connected to a cooling cable 8 that sends working gas to the tip of the torch body 1. Further, a grounding cable 6 connected to the base material 5 is connected to the cutting power source 4.
Further, a pilot cable 9 for applying a pilot arc to an electrode (not shown) of the torch main body 1 and a torch switch cable 10 are connected to the cutting power source 4 for high frequency for improving the arc start.

  On the other hand, the plasma cutting torch 7 is connected to a pilot cable 9 and a torch switch cable 10 which are led from the cutting power supply 4 with a built-in electric lamp, and to which a cooling cable 8 is connected. The working gas is supplied from the cooling cable 8 to the torch body 1.

As described above, the plasma arc cutting device 11 is configured.
At the time of arc start, a high frequency generator (not shown) provided in the cutting power source 4 guides high frequency to the pilot cable 9 and serves as an air plasma gouging nozzle provided in the torch body 1 shown in FIG. After generating a high frequency between the nozzle 17 and the electrode 16 and causing dielectric breakdown, the pilot arc is blown, the current from the base material 5 is sensed and transferred to the main arc, and the base material is melted and blown off and cut. I do.

  In the air plasma gouging, unlike the cutting nozzle, the arc plasma nozzle 17 is used to weaken the arc restraint at the nozzle tip and widen the heat input width. Unlike the cutting, the welding bead and the base metal surface are used. A gouging operation is carried out by melting and grooving or scraping the back surface of the welded portion such as a defective portion or the first layer. In the conventional nozzle for air plasma gouging, when the base material 5 and the nozzle 17 come into contact or abnormally close to each other, the base material 5 and the nozzle 17 become the same potential, coupled with the weakness of arc restraint, through the nozzle 17. It was easy for an unintended current to flow through the base material 5.

  Further, Patent Document 2 and Patent Document 3 are further disclosed for the cutting nozzle, but the heat resistance of the rubber-based adhesive that is the insulating portion is insufficient, or the manufacturing cost of silicon nitride ceramics is high. It was scarce.

JP-A-3-114677 JP 58-35059 A JP-A-9-192840

  However, in the conventional configuration, it is difficult to stabilize the arc, it is difficult to obtain a high-quality gouging result, and the degree of wear of the nozzle is large. As a result, in order to stabilize the arc, the base material and the nozzle must be electrically insulated while maintaining a spatial distance, and the quality of gouging varies from worker to worker, and the burden on the worker is high. there were.

  The present invention suppresses exhaustion of the nozzle for air plasma gouging to prevent damage, enables continuous use for a long time, reduces the burden on the worker, and enables high-quality gouging independent of the worker. An object of the present invention is to provide a practical air plasma gouging nozzle.

In order to solve the above problems, the air plasma gouging nozzle of the present invention is:
An air plasma gouging nozzle for generating a plasma arc to process a base material, comprising a conductive portion that is detachably electrically connected to a torch body, and electrically connects the conductive portion and the base material So as to insulate, at least the insulating portion that insulates the front end side of the opening of the conductive portion,
The insulating part is integrally formed with the conductive part, the insulating part is made of a heat-resistant resin having high thermal conductivity, and the insulating part has an angle α with respect to the nozzle shaft of 30 ° or more and 45 ° or less. It has an inclined portion that can follow the surface, and the thickness is 2 mm or more.

  In addition to the above, the air plasma gouging nozzle of the present invention has a recess for preventing axial displacement and a bottom surface of the recess so as to prevent relative displacement between the conductive portion and the insulating portion. And one or more radially disposed grooves that prevent rotation about the axis.

  In addition to the above, in the air plasma gouging nozzle of the present invention, the conductive part has an orifice part through which a compressed gas for operation passes toward the base material, and the orifice part is a part of the conductive part. An outer diameter is small with respect to an opening part, and it attaches / detaches from the said opening part.

  In the present invention, by providing an insulating portion made of a heat-resistant resin having high thermal conductivity on the outer periphery of the nozzle for air plasma gouging, the nozzle can be prevented from being damaged and used continuously for a long time. By providing an inclined portion that can follow the surface, the burden on the worker is reduced, and high-quality gouging that does not depend on the worker is enabled.

The figure which shows the principal part of the plasma cutting torch in Embodiment 1 of this invention Detailed view of the nozzle for air plasma gouging in Embodiment 1 of the present invention Detailed view of air plasma gouging nozzle in embodiment 2 of the present invention (A) The top view of the orifice seen from the opening part side of the nozzle for air plasma gouging in Embodiment 2 of this invention, (B) The front view of the orifice of the nozzle for air plasma gouging in Embodiment 2 of this invention The figure which shows schematic structure of the conventional plasma cutting device The figure which shows the principal part of the conventional plasma cutting torch

(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 1 shows the main part of the plasma cutting torch. The inner metal fitting 12 and the outer metal fitting 13 are coaxially combined so as not to be electrically short-circuited with the insulating cylinder 14 therebetween.
The inner metal fitting 12, the outer metal fitting 13, and the insulating cylinder 14 are covered with a mold insulator 15 that covers the outer peripheral portion to form the torch body 1. The electrode 16 and the nozzle 17 which is a nozzle for air plasma gouging are combined with the inner metal fitting 12 and the outer metal fitting 13 by screwing, respectively, and the electrode 16 and the nozzle 17 are arranged apart from each other. The

Further, the shield cup 25 is attached to the outer metal fitting 13 in a screwed manner from the opening side.
FIG. 2 shows a detailed nozzle portion of the nozzle 17 for air plasma gouging. Air plasma gouging uses a nozzle 17 for air plasma gouging, weakens the restraint of the plasma arc, widens the heat input width, and melts the weld bead and the base metal surface to dig a groove, or creates a defective portion or first The operation of removing the back surface of the welded portion such as a layer is performed.

  The nozzle insulating part 19 as an insulating part is a nozzle type that is fitted into the tip side of the nozzle conductive part 18 or is integrally molded by insert molding with a heat-resistant resin such as a thermosetting resin and a heat conductive resin. The conductive portion 18 is attached to the outer peripheral portion on the distal end side.

  Specifically, the nozzle insulating portion 19 is provided with a nozzle recess 23 for preventing the nozzle 17 from shifting in the axial direction with respect to the nozzle axial direction, and a bottom surface of the nozzle recess 23 for preventing rotation around the nozzle axis. There are two or more groove-shaped V-shaped grooves or R / U-shaped grooves and the like, and a drop prevention structure 24 such as a movement in the nozzle axis direction around the nozzle axis and around the nozzle axis. Mounted to limit rotation. The omission prevention structure 24 may be formed by knurling.

In addition, by using a heat-resistant resin having high thermal conductivity for the nozzle insulating portion 19, it is possible to prevent a significant deformation of the nozzle itself when it comes into contact with a high-temperature base material, to ensure mechanical strength, and to be inexpensive. It becomes possible to produce.
The relative heat-resistant temperature of the nozzle insulating portion 19 is improved by using a high heat-conductive heat-resistant resin obtained by adding a heat-conductive filler to the resin. Since the surface temperature of the outer peripheral portion of the nozzle conductive portion 18 rises to about 130 ° C., a thermosetting resin or a super engineering plastic of a thermoplastic resin having a heat resistant temperature of 150 ° C. or higher is used as the heat resistant resin. For thermosetting resins, glass fiber-filled phenolic resin and PDAP (diallyl phthalate) have a heat resistant temperature of 270 ° C, and for thermoplastic resins, PI (polyimide) has a high heat resistant temperature of 300 ° C or higher. Is preferably used.

  Further, the nozzle insulating portion 19 has a nozzle inclined portion 26 having a thickness t = 2 mm or more and an angle α = 30 ° or more and 45 ° or less with respect to the torch body axis or the nozzle axis.

  Thereby, by providing an inclined portion to follow the surface of the base material in the nozzle insulating portion 19 in which movement in the nozzle axis direction and rotation around the nozzle axis are restricted, the operator's gouging work is stabilized, The gouging result depending on the worker can be made uniform.

  In addition, when the angle α is less than 30 ° with respect to the nozzle axis, the gouging angle for removing the back surface of the welded portion becomes shallow and the gouging operation is difficult to stabilize, and when the angle α exceeds 45 °, In the gouging operation, the gouging angle becomes deep, and there is a possibility that the scrap of the work that has been melted and scraped off by the gouging operation will bounce back to the operator himself. Further, when the thickness of the nozzle insulating portion 19 is less than t = 2 mm, the withstand voltage and mechanical strength are lowered, and the thickness t = 2 mm or more of the nozzle insulating portion 19 is preferable.

  According to the first embodiment of the present invention as described above, the nozzle insulating portion 19 prevents unintended electrical contact between the nozzle 17 and the base material 5, and the gap between the outer peripheral portion of the nozzle 17 and the base material 5 is prevented. Since insulation can be ensured, poor construction due to arc instability and damage to the nozzle 17 are reduced. In addition, due to the copying structure of the nozzle inclined portion 26, a good gouging result can be easily obtained by the gouging work independent of the operator.

(Embodiment 2)
Next, the second embodiment will be described with reference to FIGS.
FIG. 3 shows a detailed view of the nozzle 17 which is a nozzle for air plasma gouging,
FIG. 4 shows a detailed view of the orifice portion provided in the nozzle 17. 4A is a plan view of the orifice portion 20 as viewed from the opening 22 side of the air plasma gouging nozzle, and FIG. 4B is a front view of the orifice portion 20 of the air plasma gouging nozzle.

  The difference from the first embodiment is that the nozzle 17 has an independent structure in which the working gas that becomes a plasma arc passes and the orifice portion 20 that is heavily consumed by the arc can be replaced. The orifice portion 20 is attached to the nozzle conductive portion 18 of the nozzle 17 by a screwing method. The orifice portion 20 has a slit portion 21 made of a narrow groove for attaching to the nozzle conductive portion 18 from the opening portion 22 side at the tip of the nozzle 17, and the orifice portion 20 is an opening of the nozzle conductive portion 18 of the nozzle 17. The outer diameter is smaller than that of the portion 22, and a screw is formed on the outer periphery.

  As a result, the orifice portion 20 can be directly and detachably attached to the inside of the nozzle conductive portion 18 from the opening 22 side, which is the tip side of the nozzle 17, using a flathead screwdriver or the like.

  According to the second embodiment as described above, it is possible to directly replace the orifice portion that is heavily consumed without removing the components such as the shield cup at the time of replacement by making the orifice portion independent.

  As described above, at the time of arc start, it is necessary to cause a pilot arc to flow between the nozzle conductive portion 18 of the nozzle 17 and the electrode 16 to generate a pilot arc, and to perform dielectric breakdown with the base material 5. In the plasma gouging nozzle, since the conductivity inside the nozzle 17 is ensured by the nozzle conductive portion 18, a pilot current can be flowed, and the same good arc start property as in the prior art can be secured.

  As described above, the air plasma gouging nozzle of the present invention is configured to have the insulating portion on the outer periphery on the tip side of the opening portion of the nozzle and have a shape following the insulating portion. In this way, an insulating part made of a highly heat-resistant heat-resistant resin is provided on the outer periphery of the nozzle conductive part on the surface that may come into contact with the base material, so that unintended electrical contact between the base material and the nozzle is avoided during gouging By doing so, damage to the gouging nozzle can be reduced. Furthermore, by providing a copying portion with an inclined insulating portion, it is possible to copy the surface of the base material, and variation in gouging quality by the operator can be reduced.

  The plasma gouging nozzle of the present invention is useful industrially because it can provide a long life and high quality gouging results.

DESCRIPTION OF SYMBOLS 1 Torch main body 2 Compressor 3 Regulator 4 Power supply for cutting 5 Base material 6 Grounding cable 7 Plasma cutting torch 8 Cooling cable 9 Pilot cable 10 Torch switch cable 11 Plasma arc cutting device 12 Inner metal fitting 13 Outer metal fitting 14 Insulating cylinder 15 Mold insulator 16 Electrode 17 Nozzle 18 Nozzle conductive part 19 Nozzle insulating part 20 Orifice part 21 Slot part 22 Opening part 23 Nozzle recess 24 Drop prevention structure 25 Shield cup 26 Nozzle inclined part

Claims (3)

An air plasma gouging nozzle for generating a plasma arc to process a base material,
It consists of a conductive part that is detachably electrically connected to the torch body,
In order to electrically insulate the conductive part and the base material, the outer periphery is provided with an insulating part that insulates at least the tip side of the opening of the conductive part,
The insulating portion is integrally formed with the conductive portion, and the insulating portion is made of a heat-resistant resin having high thermal conductivity. The insulating portion has an angle α with respect to the nozzle shaft of 30 ° to 45 °, An air plasma gouging nozzle having an inclined portion that can follow the surface and a thickness of 2 mm or more. In order to prevent relative displacement between the conductive part and the insulating part,
A recess to prevent axial displacement,
2. The air plasma gouging nozzle according to claim 1, further comprising: one or more radially disposed grooves that prevent rotation about an axis on a bottom surface of the recess. The conductive portion has an orifice portion through which compressed gas for operation passes toward the base material, and the orifice portion has a small outer diameter with respect to the opening portion of the conductive portion, and is attached and detached from the opening portion. The air plasma gouging nozzle according to claim 1.