JPH0239657Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an arc torch that prevents the occurrence of abnormal discharge or discharge due to contact between the charged part of the plasma arc torch and the workpiece, and improves electrical fastness. It is.

Conventionally, a commonly used plasma arc torch for cutting or welding workpieces has a torch body 1 whose outer periphery is molded with a green mold, and a cathode body (not shown), as shown in Fig. 1. The cathode 4 is arranged facing the center of the nozzle anode 3 so that the cathode 4 detachably attached and the nozzle anode 3 screwed to the anode body 2 are concentric,
In the meantime, a gas flow path A for forming a plasma arc is formed, and a working gas is supplied to this gas flow path A from a working gas supply source (not shown), and between the cathode 4 and the workpiece 5. It is designed to generate a plasma arc that serves as a heat source.

Further, the cooling water passage B is supplied with cooling water from a cooling water supply source (not shown) to cool the nozzle anode 3, and then discharged through the cooling water passage B'. C is a shielding gas flow path. The cap 6 is connected to the anode body 2 to prevent leakage of shield gas to the outside.
They are screwed together via a ring 7 to protect the nozzle anode 3 against greenery, and also to supply shielding gas etc. from the shielding gas flow path C and guide it to the tip of the torch.

Generally, in the case of welding, a shielding gas is flowed to prevent the outside, ie, air, from getting mixed in, and is used to obtain a good welding result. Furthermore, in the case of cutting, it can be used as a flow path for supplying active gas, inert gas, and water using the latent heat of vaporization.

Therefore, in the plasma arc torch, a pilot arc 9 is first created between the nozzle anode 3 and the cathode 4 using an appropriate method such as high frequency 10 when starting the arc.
It generates a small current plasma arc called a plasma arc, and transitions to the main arc when a signal to start the main arc is supplied. This high frequency wave 10 is very habitual and induces various forms depending on its strength. Usually, a path is formed between the nozzle anode 3 and the cathode 4 to generate a high frequency wave 10. An O-ring 7 is inserted between the outer sheath of the torch body 1 and a cap 6 screwed to the anode body 2 to prevent leakage of shield gas etc. to the outside.
When the O-ring 7 is close to a charged object (not shown) that holds the torch, etc., the bath surface distance is small due to leakage of shield gas due to weak tightening of the cap 6, etc. O-ring 7
There is a problem in that a phenomenon of high-frequency abnormal discharge 11 occurs from the end of the tube. Due to the phenomenon of this abnormal discharge 11, not only the high frequency power is dispersed, but also the high frequency power between the nozzle anode 3 and the cathode 4 is attenuated, making it impossible to stably generate the pilot arc 9. If the generation of the pilot arc 9 becomes unstable in this way, arc start errors will be repeated frequently, and as a result, the surface of the cathode 4 will have a cleaning action, which is generally said to occur, and only high frequency waves will be generated, causing the arc to become unstable. There were some problems, such as a phenomenon in which the system did not occur. Moreover, if this is repeated further due to the abnormal discharge 11, not only will the O-ring 7 deteriorate, but the outer sheath of the torch body 1 will be destroyed, and finally, during plasma arc generation, there will be a gap between the material and the workpiece 5, etc. However, an abnormal arc discharge different from the plasma arc is generated, which causes the torch body 1 to burn out.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional technology and prevent short circuits due to abnormal discharge or contact between the charged part of the arc torch and the workpiece or the charged object that holds the torch. The purpose of the present invention is to provide an arc torch with enhanced electrical fastness.

In the present invention, between the end of the cap screwed to the anode body and the end of the jacket of the torch body,
It is characterized by the insertion of green-proof protective packing that surrounds both ends.

An embodiment of the present invention will be explained with reference to FIG. Since the basic configuration is the same as that of the conventional arc torch shown in FIG. 1, the description thereof will be omitted, and the portions of the present invention will be mainly explained. The same parts as in FIG. 1 are given the same reference numerals. The structure of FIG. 2 according to the present invention differs from the conventional example shown in FIG. 1 in that a packing 8 shown in FIG. 2 is attached to the location where the O-ring 7 of FIG. 1 is attached. The configuration of this packing 8 will be explained in detail below. This packing 8 is made of an electrically insulated and heat-resistant insulated material, and is inserted between the upper end of the cap 6 and the lower end of the outer sheath of the torch body 1, and is inserted between both ends and its outer periphery. The outer periphery is cylindrical so as to surround the cap, and the inner wall has a protrusion, which also serves as packing so that the cap 6 can be screwed and tightened to shut off the shield gas flow path C from the outside.
A ring-shaped space zone D is formed in the portion where the packing 8 surrounds both ends, and this space zone D prevents deterioration of the packing 8 due to radiant heat from the cap 6 when an arc occurs, and increases the bath surface distance. Therefore, even if it comes into contact with the workpiece 5, there is no risk of generating abnormal discharge 11 unlike in the conventional case.

As described above, according to the present invention, both ends of the cap 6 and the torch body outer sheath are surrounded by the packing 8 to increase the bath surface distance, thereby preventing abnormal discharge phenomena even when a strong high-frequency voltage is directly applied. I can,
Therefore, it is possible to eliminate obstacles to arc generation due to burnout of the torch body and attenuation of high frequency power.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of a conventional arc torch, and FIG. 2 is a longitudinal sectional view showing an embodiment of the present invention. 1...Torch body, 2...Anode body, 3...Nozzle anode, 4...Cathode, 5...Work material, 6...
Cap, 8... Packing, A... Working gas flow path, C... Shield gas flow path.

Claims (1)

[Scope of utility model registration request] A cathode, an anode body formed in a double cylindrical shape with a uniform gap at the tip, and a cathode body holding the cathode and the anode body are electrically insulated from each other and from the outside. A torch body integrally molded; a nozzle anode that is screwed onto the tip of the inner cylindrical portion of the anode body and concentrically surrounds the cathode across a working gas passage; and a nozzle anode that is screwed onto the tip of the outer cylindrical portion of the anode body. In a plasma arc torch comprising an insulating cap concentrically surrounding the nozzle anode across a shielding gas passage, both ends of the cap are placed between an end of the cap and an end of the torch main body jacket. A plasma arc torch characterized by inserting a surrounding insulating protective packing.