JPH0312463Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Field of application of invention] The present invention relates to a plasma arc torch.

[Background of the idea]

FIG. 1 shows a conventionally commonly used plasma arc torch.

In this figure, a cathode body 2 and an anode body 3 are installed inside a torch body 1, the outsides of the cathode body 2 and anode body 3 are covered with an insulator 4, and the cathode body 2 and anode body An electrode 5 is arranged inside 3.

The cathode body 2 is equipped with a collet 6 for holding the electrode 5, and a cap 7 for pressing the collet 6 to prevent the electrode 5 from falling off. Note that an O-ring 8 is interposed between the cathode body 2 and the cap 7 to prevent gas leakage.

On the other hand, the anode body 3 is equipped with an insulating guide 9 made of a highly electrically insulating material and having a gas flow path on its outer peripheral surface, a nozzle electrode 10, and a shield cap 11 made of an insulating material. ing. The insulated guide 9 prevents the axis of the electrode 5 from shifting, and the nozzle electrode 10 narrows the plasma arc. Furthermore, the shield cap 11 forms a shield gas flow path necessary for plasma welding and prevents short circuits with the outside. The shield cap 11 is attached to the anode body 3 via a packing 12 to prevent leakage of the shield gas.

The cathode body 2 includes a pipe 13 that also serves as a cooling water flow path for energizing and cooling the torch, and a pipe 15 for circulating cooling water from the anode body 3.
and a pipe 17 for supplying plasma gas are connected. On the other hand, the anode main body 3 includes a pipe 14 that also serves as a cooling water flow path for energizing and cooling the tote, a pipe 16 for circulating cooling water to the pipe 15 of the cathode main body 2, and a pipe 16 for supplying shield gas. A pipe 18 is connected thereto. Note that the cooling water pipes 15 and 16 are connected to each other by an insulating tube 19 outside the grip, but in FIG. 1, for convenience, both pipes 15 and 16 are shown as being in contact midway. There is.

A pipe 13,1 connected to the cathode body 2
5, 17, and the pipe 1 connected to the anode body 3
An insulating plate 20 with excellent electrical insulation is interposed between the pipes 13 to 18.
The outside of the group 18 is protected by a grip 22 made of a material with excellent electrical insulation properties to prevent troubles such as damage to the torch body 1 and electric shock due to abnormal discharge or short circuit.

Generally, during welding and cutting operations, workers often hold the grip 22 in their hands. Therefore, if the outer diameter of the grip 22 is large, it will be difficult to grip and the operability will deteriorate, so it is made as small as possible. As a result, the cross-sectional area of the grip 22 that accommodates the pipes 13 to 18 serving as the charging section is limited, so that the pipes 13, 15, 17 connected to the cathode body 2 and the anode body 3 are
An insulating plate 20 is interposed between the pipes 14, 16, and 18 connected to the pipes to protect them.

However, in the prior art, a gap 21 may occur between the insulator 4 and the insulating plate 20 covering the cathode body 2 and the anode body 3, as shown in FIG.

Normally, when generating a plasma arc, a small current arc called a pilot arc is generated. That is, a gas is flowed from the plasma gas supply pipe 17 between the tip of the electrode 5 and the inner wall of the nozzle electrode 10, and an initial high frequency voltage is applied to generate a pilot arc. In this case, if the gap 21 is generated between the insulator 4 and the insulating plate 20 as described above, the electrode 5 and the nozzle electrode 10
High frequency discharge occurs between the pipe 17 and the pipes 14 and 16 when arc discharge is difficult to occur between the pipes 17 and 14 and 16. As a result, the insulator 4 gradually carbonizes and its insulation properties deteriorate, or the pipes 14, 16, 17 are gradually damaged by the pipe discharge and become unusable due to holes.

Furthermore, when the ambient temperature or humidity is high,
Due to the cooling water flowing through the pipes 13, 15 and 14, 16, and the ambient temperature and humidity,
Water droplets adhere to the surfaces of the electrodes 3, 14, 15, and 16, reducing their insulation properties, making them prone to abnormal discharges and short circuits. This phenomenon occurs when a plasma arc occurs.
This may also occur due to a temperature difference between the inlet and outlet sides of the cooling water. In particular, in plasma cutting, etc., a gas having a high dissociation voltage such as Ar and N ₂ or H ₂ gas is used in combination with the plasma gas, so a power supply device (not shown) with a high voltage is used. In this usage mode, a gap 21 is created between the insulator 4 and the insulating plate 20, and when the creepage distance of the insulation becomes short, abnormal discharge and short circuit are likely to occur.

However, in the conventional technique in which the insulating plate 20 is simply opposed to the insulating material 4, the insulating material 4 is
There is a drawback that the generation of the gap 21 between the insulating plate 20 and the insulating plate 20 cannot be prevented.

[Purpose of invention]

An object of the present invention is to provide a plasma arc torch that eliminates the drawbacks of the prior art and can reliably prevent troubles such as abnormal discharge and short circuit between the pipe connected to the cathode body and the anode body. It is in.

[Summary of the idea]

The features of the present invention include an insulator that covers the cathode body and the anode body, and an insulating plate interposed between the pipe connected to the cathode body and the pipe connected to the anode body, and the insulator is covered with the insulator. An insulator is provided to insert or overlap the ends of the plates, and this configuration ensures that the above objective can be achieved.

[Example of idea]

Hereinafter, the present invention will be explained based on the drawings.

FIG. 3 shows the first embodiment of the present invention.
At the end of the insulator 4 covering the cathode body and the anode body,
An insulating board 23 is embedded and fixed. Note that in FIG. 3, the cathode body and the anode body are omitted.

The insulating board 23 is made of a highly electrically insulating material containing glass fiber with low hygroscopicity, or ceramic, and the insulating board 23 has pipes 13 to 1
8 insertion holes and a fitting groove 24 at the end of the insulating plate 20 are provided.

Pipes 13, 15, 17 connected to the cathode body and pipes 14, 16, 18 connected to the anode body are inserted into the insertion hole provided in the insulation board 23 in one half and the other half, respectively. It is inserted into the fitting groove 24 in sections, and the end of the insulating plate 20 is inserted into the fitting groove 24. In this case, the tip end surface of the insulating plate 20 and the inner end surface of the fitting groove 24 do not need to be in contact with each other, and the fitting groove 24 may cover the end of the insulating plate 20 .

Note that the reference numeral 22 in FIG. 3 indicates a grip.

In the plasma arc torch of the above embodiment, an AC voltage of 10,000 V is applied between the cathode body 2 and the anode body 3.
Even if a high voltage such as ~15,000 V is applied, the end of the insulating plate 20 is inserted into the fitting groove 24 provided in the insulating board 23, and as a result of the end of the insulating plate being covered by the fitting groove 24, a pilot arc will not occur. Even if arc discharge is difficult to occur between the electrode and the nozzle electrode, high frequency discharge will not occur between the pipe 17 and the pipes 14, 16, and the pipes 13, 14, 15, 1
Even if water droplets adhere to the pipe 6 and it contacts the insulating plate 20, there will be no abnormal discharge or short circuit.
It was confirmed that Nos. 4, 15, and 16 were not damaged.
In addition, since the creepage distance of the insulation can be made long, when the insulation resistance of the insulator 4 is measured by the amount of insulation resistance of 500V,
Sufficient insulation of 10 μΩ or more can be obtained, and troubles such as abnormal discharges and short circuits can be reliably prevented even when a high voltage power supply is used, for example. Next, FIG. 4 shows a second embodiment of the present invention. In this embodiment, a protrusion 25 made of the same electrically insulating material is provided at the end of the insulator 4. An insulating plate 20 is in superimposed contact with the upper surface of the insulating plate 20 .

As a result, this second embodiment operates in the same manner as the first embodiment.

In the second embodiment, a fitting groove may be formed inward from the end surface of the insulator 4, and the end of the insulating plate 20 may be inserted into the fitting groove.

Note that in the first and second embodiments, other structures and operations are the same as those shown in FIGS. 1 and 2.

[Effect of idea]

The present invention has the structure and operation explained above,
According to the present invention, no gap is created between the insulating material and the insulating plate in any manner of use as a torch, so the gap between the pipe connected to the cathode body and the pipe connected to the anode body due to such a gap This has the effect of reliably preventing troubles such as abnormal discharge and short circuits.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a conventional plasma arc torch, Fig. 2 is a sectional view taken along the line - in Fig. 1, and Figs. 3 and 4 are main parts of the first and second embodiments of the present invention. FIG. 4...Insulator covering the cathode body and anode body, 1
3-18...Pipe, 20...Insulating plate, 23...
An insulating board fixed to an insulating material, 24... a fitting groove of an insulating board, 25... a protrusion provided on an insulating material.

Claims (1)

[Scope of utility model registration request] A cathode body to which a plurality of pipes are connected and which holds an electrode at its tip is electrically insulated from an anode body to which a plurality of pipes are connected and which holds a nozzle at its tip, and the plurality of pipes are polarized at a predetermined end face. In the plasma torch, the plasma torch includes a torch body that is integrally molded into two groups of different polarities, and an insulating plate that is arranged on the end surface and insulates the two groups of pipes, the two groups of pipes on the end surface are 1. A plasma torch characterized in that a groove or a protrusion is formed at a dividing position, and an end portion of the insulating plate is configured to be superimposed on the groove or protrusion of the torch main body.