JPH0339791B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an air plasma arc torch, and more particularly to an air cooled air plasma arc torch used for cutting relatively thick metal materials.

PRIOR ART AND ITS PROBLEMS Air plasma arc cutting has long been used due to the distinct advantage of higher arc temperatures compared to plasma arc cutting using oxidizing flame torches and certain gases such as carbon dioxide. It's here. Furthermore, in the current air plasma arc technology, which is kept free of oxygen by an air shield, an exothermic reaction occurs when cutting ferrous materials, and the quality of the cut surface is almost the same as the cut surface with an oxidizing flame torch. A situation has arisen in which the values are approximated in terms of .

The use of hand-operated air plasma arc torches has been limited to relatively low power torches used to cut metal materials up to about 5 mm thick. Recently, with the introduction of high-quality steel for vehicle body materials, for example, the need for high-output air plasma arc torches has become apparent. The power of the torch for such materials is so high that it is required to cut materials reaching a thickness of about 40 mm.

Conventional high-power torches have been water-cooled. Water cooling allowed the torch to be maintained at a sufficiently low temperature and allowed the use of low pressure and low temperature coating materials commensurate with the complexity of the torch metal components. However, water-cooled torches require additional structure, making the torch less convenient to use than air-cooled torches. On the other hand, air-cooled torches are obviously extremely simple and economical, but if the torch is to have a high output, it is impossible to keep the torch at a sufficiently low temperature. The above-mentioned coating materials cannot withstand the high temperatures generated by the heat generated during use of high-power torches.

In order to replace parts such as electrodes and cutting tips housed within the torch, it is often necessary for an operator to remove the shield member from the torch. If the torch is used relatively close to the power source,
The operator does not have to take the trouble of confirming that the switch is turned off before disassembling the torch, and is free from the risk of receiving a strong electric shock from energized parts due to a confirmation error.

Adjustment of the power supply to low power air plasma arc torches was done in its early technology stages without adjustment of other factors such as air volume supply. However, it is now recognized that for more efficient operation the power supply for an air plasma should not be the same for different inputs. To address this point,
Although it is possible to have different torches for different power ranges, this is not practical enough.

As mentioned above, torches require frequent maintenance. After this cleaning, the torch is often not reassembled properly or the components are not replaced. In such a case, even if power is supplied to the assembled torch again, the arc cannot be directed to the required location, ie, the plasma chamber. For example, arcs can form in undesired paths, resulting in short circuits, etc. In this manner, the repeated action of the arc on the plastic material of the torch carbonizes the plastic material. Once a path of low insulation resistance is formed by this carbonized plastic material, there is a tendency for arcing to occur along that path even if the torch is properly reassembled. Once the torch develops this tendency, it is impossible to restore it to its original state again, and recovery by maintenance is impossible.

An object of the present invention is to solve the above-mentioned problems and to make it possible to increase the output of an air-cooled air plasma arc torch.

Summary of the Invention The object of the present invention is to attach an anode and a cathode concentrically to the distal end of a metal body, surround the outside with an annular shield member, and connect an air supply tube to the proximal end of the body. In the air plasma arc torch, a passage is provided passing through the metal body and the center of the concentrically arranged anode and cathode, and the metal body connects the air passage to a plasma arc generation passage and an air shield. The metal body is coated with a thermosetting resin by high-pressure transfer molding. This is achieved by an air-cooled air plasma arc torch characterized by the following.

The applicant has discovered that the provision of a coating of said plastic part with a thermosetting resin cross-linked at elevated temperatures facilitates the use of the torch at higher temperatures and, as a result of this, the operation of the torch at higher power inputs. We have discovered that this is possible. Previously, this technique was only possible in the low pressure technologies mentioned above.

In a preferred embodiment of the present invention, an annular conductive section having a concentric outer peripheral surface is provided between the thermosetting resin coated portion and the annular shield member, and the conductive section The wall thickness of the conductive section is varied by an eccentric inner circumferential surface, and a power supply conductor extends through the covered portion and slightly protrudes from the outer circumferential surface of the covered portion, and the conductive section has a thinner wall portion. When the thick portion is located at a position corresponding to the conductor wire, it is separated from the conductor wire, and when the thick portion is at a position corresponding to the conductor wire, it is held between the conductor wire and the annular shield member and is in a locked state. A plasma arc torch is provided. In this case, the conductive wire is further provided on the outer circumferential surface of the covered portion with two cut ends separated, and the thinner part of the conductive section is located at a position corresponding to the conductive wire. Sometimes, the circuit is opened by separating from the two cut ends, and when the thick part is in a position corresponding to the conductor, the circuit is closed by contacting the two cut ends. It is desirable that the wall thickness be determined as follows.

In a preferred embodiment of the present invention, an air adjustment member is further disposed in the air passage, and the air adjustment member has a bulge having a size that is located in the air flow of the two types of ports and provides flow resistance. and position to adjust air flow to the disparate ports, the air adjustment member being interchangeable with other air adjustment members having ridges of different sizes and locations. An air-cooled air plasma arc torch can be provided.

According to an embodiment of the present invention, the shielding air passage is configured to be inclined in the radial direction of the torch such that the electric power required to generate an arc across the passage is greater than the electric power required to generate a torch arc. It is desirable to have one.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the torch head has shaft hole 1.
2. Shaft hole 12
is provided with a female thread 14 for screwing into the male thread of the air adjustment member 16. Air adjustment member 16
is hollow and open at both ends in the axial direction, and is disposed on the same axis as the shaft hole 12. The air adjustment member protrudes beyond the shaft hole 12 into the cathode 18 and extends to the rear end surface of the cathode electrode holder. The cathode electrode holder is removably attached to the body 10.

The air adjustment member 16 has a portion with an outer diameter smaller than the axial bore 12, which portion forms a chamber 20 within the axial bore 12. Air adjustment member 16
A shoulder portion 21 closes the rear portion of the chamber 20 in the radial direction, and is configured to limit and adjust the opening degree of the shield port 24. A first radially extending port 22 communicates with the chamber 20 for supplying plasma air. The radially extending second port 24 is
It opens into the chamber 20 for supplying air to form an air shield. The second port 24 is
It communicates with a recess 26 formed in the outer peripheral surface of the body 10. A main insulating material 28 is provided over the body 10 and over the recess 26 to form a chamber. The insulating material 28 is preferably made of a material having excellent heat resistance and electrical insulation properties, such as silicon dioxide. The insulating material 28 extends along the body 10 to the front of the port 22. The surface 30 of the insulating material 28 near the port 22 is not simply a surface extending in the radial direction, but has a shape that increases the surface area. The purpose of having such a shape will be explained later.

The anode 32 is in a conventional configuration with an open end.
It is fixed concentrically to the insulating material 28. An anode 32 extends beyond the surface 30 of the insulating material 28 and includes a chamber 3 between the anode and the body 10.
4, and the chamber 34 has a port 2.
2 is in common. A tip holder 36 is removably attached to the anode 32 and surrounds the cathode 18 with a gap forming an annular passage 38 into the chamber 34. The plasma arc restricting tip 40 is removably attached to the tip holder 36. Chip 40
is provided concentrically with respect to both the tip holder 36 and the cathode 18.

The torch head is covered with a plastic material part 42 which is additionally cross-linked at high temperatures and is therefore corrosion resistant in hot conditions.
The coating with the plastic material part 42 can be obtained by high-pressure compression molding.

The conductors 44, 46 which are connected to the control circuit for the power supply to the torch are embedded in the coated plastic material member 42, leaving their ends 48, 50. Ends 48, 50 are exposed and extend parallel to the axis of the torch. The annular shield member 52 is preferably formed of a ceramic material and includes an anode, a
It is removably attached to a cover plastic material member 42 surrounding the tip holder and tip to form an annular air gap 54. In order to position the torch with a gap from the workpiece 57, the guide clip 55 is attached to the shield member 52.
is removably fitted. The shield member 52 includes a conductive section 56 near the inner end of the annular shield member 52 that contacts the coated plastic material member 42. As shown in FIG. 2, the conductive section 56 is provided eccentrically, and the center of the inner peripheral surface of the conductive section 56 is located off the axis of the shield member 52. As shown in FIG. The shield member 52 is kept concentric with the rest of the torch at all times by engaging the covering plastic material member 42. However, rotation of shield member 52 about its axis (from the position shown in FIG. 2) causes eccentric conductive section 56 to contact conductor ends 48 and 50, thereby closing the control circuit. . In this position, the shield member 52 remains locked onto the torch and is only removable when reversely rotated to remove the conductive section 56 from the conductor ends 48,50; The shield member 52 can be pulled out axially and removed. Accordingly, the torch is constructed such that it cannot receive input for actuation unless the shield member is properly positioned and locked onto the torch.

In operation, air is supplied to the axial bore 12 of the body 10 by power and air tubes. Air contacts the rear of the cathode electrode holder 18 through the air conditioning member 16, thereby assisting in cooling the cathode. The supplied air then moves in the opposite direction along the chamber 20 to surround the outer circumferential surface of the air conditioning member 16. A sudden change in the direction of movement of the air flow can cause transport inclusions, such as water, oil or solid contaminants, to accumulate on the rear end face of the cathode electrode holder, which can interfere with the operation of the torch. The airflow flowing through the chamber 20 is
It is branched into a first flow for plasma generation flowing through port 22 and a second flow flowing through port 24 . This air flow division is effected by a circumferentially extending ridge 62 near the port 22 on the air conditioning member 16. As shown in FIG. 1, the ridges 62 have a shape similar to the top surface of an aircraft wing and act to increase the velocity and reduce the pressure of the airflow as it passes through the port 22. The precise size and positioning of ridge 62, along with adjustment by step 21, determines the rate of airflow that passes through port 22 to form a plasma. Therefore, the torch may be replaced with other air conditioning members with different formations of the ridges 62 and steps 21 even when different amounts of plasma generating air are required for use at different power levels. can be easily adapted. In this case, of course, there is no need to replace other components of the torch.

Air through port 22 flows through chamber 34 and into passageway 38 surrounding the cathode, forming an arc. Air passing through port 24 passes through a chamber formed by recess 26 and insulation 28 and passes through insulation 2
The air flows through passage 64 in 8 and passage 66 in the anode to air gap 54, forming an air shield. The airflow to form the air shield undergoes several sharp changes in direction. These multiple redirections are very advantageous as they assist in depositing and removing foreign objects or inclusions carried by the airflow.

As previously mentioned, surface 30 is not a flat radially extending surface and is shaped to increase the tracking path along the surface. If the torch were to be combined with the wrong components, an arc could occur from the cathode body and strike the anode when the torch was operated with the shield member attached. Such an arc will form across the surface 30 of the insulation 28, but the increased tracking path for arcing, as described above, will make it easier to generate the arc than upon proper assembly of the torch. Requires high input voltage. The passageway 64 in the insulation material 28 is also formed obliquely relative to the radial plane, increasing its length. For arcing to occur between the cathode body and the anode through passage 64, surface 30
An even higher input voltage is required to generate an arc. Thus, the high input voltage required to prevent harmful arcing that can damage the torch during improper assembly of the torch is important for the torch to perform its intended function.

Effects of the Invention As is clear from the above, in the air-cooled air plasma arc torch according to the present invention, the plastic material member covering the metal body with the anode and cathode attached to the tip side is made of thermosetting resin and is a high-pressure transfer material. Since it is formed by arch molding, a coating with high heat resistance can be obtained, and as a result, the temperature during use of the torch can be increased, and the torch can have a high output.

Furthermore, if the passage in the insulating material that forms the air passage is inclined, and if the passage in the insulating material is made of an inclined surface, the distance between these is made as long as possible to prevent short-circuit arcs and prevent the surface of the insulating material from forming. Insulation deterioration due to tracking can be prevented.

In addition, if the proportion of the air flow supplied to the torch is adjusted by adjusting the size and position of the protrusion provided on the outer periphery of the air adjustment member housed within the torch, other air adjustments may be made. By simply replacing the member, appropriate adjustment of the air flow as required depending on the torch output can be easily performed.

It is very advantageous if the air passages within the torch are passaged so that they make sharp changes in direction to assist in depositing and removing foreign matter carried by the air flow.

[Brief explanation of the drawing]

The figure shows a torch according to an embodiment of the invention, the first
The figure is a front view of the longitudinal section, and Figure 2 is the − of Figure 1.
FIG. 3 is a cross-sectional view taken along a line, and FIG. 3 is an exploded perspective view. 10... Body, 12... Shaft hole, 16... Air adjustment member, 18... Cathode, 28... Insulating material, 36... Chip holder, 42... Covered plastic material member, 44, 46... Conductive wire, 52...
...Shield member.

Claims (1)

[Claims] 1. An air plasma in which an anode and a cathode are concentrically attached to the distal end of a metal body, the outside of these is surrounded by an annular shield member, and an air supply tube is connected to the proximal end of the body. In the arc torch, a passage is provided through the metal body and the center of the concentrically arranged anode and cathode, and the metal body defines the air passage as a plasma arc generation passage and an air shield passage. The metal body is coated with a thermosetting resin by high-pressure transfer molding. Air-cooled air plasma arc torch. 2. An air adjustment member is disposed within the air passage, and the air adjustment member adjusts the air flow to the different types of ports by the size and position of a protuberance that is located in the air flow of the two types of ports and acts as a flow path resistance. 2. The air adjustment member according to claim 1, wherein the air flow is adjustable and the air adjustment member is replaceable with other air adjustment members having ridges of different sizes and positions. Air-cooled air plasma arc torch. 3. The anode is installed on the outside of the metal body via an insulating material, and a shielding air passage is formed between the insulating material and the body and between the insulating material and the anode. The air-cooled air plasma arc torch according to claim 1. 4. The shield air passage is configured to be inclined in the radial direction of the torch so that the electric power required to generate an arc across the passage is greater than the electric power required to generate a torch arc. 3. The air-cooled air plasma arc torch described in 3. 5. The air-cooled air plasma arc according to claim 3, wherein the air passage is formed with an abrupt change in direction at the lower end to cause a build-up of solids carried by the air flow. torch. 6. An annular conductive section having an outer circumferential surface concentric with these is provided between the thermosetting resin coated portion and the annular shield member, and the conductive section has an eccentric inner circumferential surface. The thickness of the electrically conductive section is varied, and a power supply conductor extends through the sheathed portion and slightly protrudes from the outer peripheral surface of the sheathed portion, and the thinner part of the conductive section is located at a position corresponding to the conductor. At times, the conductive wire is separated from the conductive wire, and when the thick portion is located at a position corresponding to the conductive wire, the conductive wire is held between the conductive wire and the annular shield member to be in a locked state. 1. The air-cooled air plasma arc torch described in 1. 7. The conductive wire is provided on the outer circumferential surface of the covered portion with two cut ends separated from each other, and the conductive section is arranged so that when the thin walled portion is located at a position corresponding to the conductive wire, the conductive section The wall thickness is such that the circuit is opened by the conductor when separated from the cut end, and the circuit is closed by contacting the two cut ends when the thick part is in a position corresponding to the conductor. 7. The torch according to claim 6, wherein: