JPH027754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a plasma arc generation method that does not require complicated equipment for plasma generation.

As shown in FIG. 1, the conventional plasma welding method consists of an insert 3 provided concentrically within a shield cap 1 and an electrode rod 7 placed at the center of a torch 5. The shielding gas 9 is discharged around the nozzle opening 11 through the gap between the electrode rod 7 and the insert 3, and the pilot gas 13 is intensively injected from the nozzle opening 11 through the gap between the electrode rod 7 and the insert 3.
In between, high frequency power supply 15, pilot arc power supply 1
A voltage of 7 (approximately 200 V) is applied to generate an arc to ionize the pilot gas 13, and the ionized pilot gas 13 is concentratedly injected as a plasma jet 19 through the narrow nozzle opening 11 by pressurizing the pilot gas 13. Furthermore, base material 21
A DC voltage from a welding arc power source 23 is applied between the base metal 21 and the electrode rod 7 with the base metal 21 as the positive pole, and a plasma arc 25 is blown onto the base metal 21 for welding. Note that 27 is cooling water.

In order to generate plasma in such a plasma welding machine, as explained above, the welding device must have a complex and sufficient function as a plasma welding machine.

This invention does not require such a complicated plasma generation device, and can generate plasma using only low voltage (e.g., about 35V) multi-phase AC voltage and argon gas, which are used for normal multi-electrode TIG welding. The purpose is to provide an arc generation method.

Embodiments of the present invention will be described below with reference to the drawings.

In Figures 2 and 3, three non-consumable electrodes 29, 31, 33, such as dungsten welding rods, are placed extremely close to each other in a parallel triangular shape at regular intervals so that an arc can be generated between the electrodes. A Teig torch 37 is arranged inside the gas cup 35 facing the nozzle opening 38. Here, apply the same amount of argon gas to the gas cup 35 as during normal multi-electrode TIG welding.
The diameter of each electrode consisting of non-consumable electrodes 29, 31 and 33 of the tungsten welding rod is 1.6 mm.
mm, the gap between the tips of each electrode was approximately 1 mm, low voltage (approximately 35 V, 50 A) three-phase AC power was supplied between each electrode, and the base material 39 such as Ni-Cr steel was
When connected to the neutral point of phase AC power, 3
The interphase arc 41 occurs and the base material 39
An arc 43 is also generated between each of the non-consumable electrodes 29, 31, and 33, and a total of six arcs are generated at the tip of the Teigue torch 37 at the same time.

In this case, the arc heat overlaps with each other at the center tip of the Teigu torch 37, and the temperature is much higher than that of the normal arc 45 at the outside, creating a high temperature arc atmosphere and generating plasma 47 between it and the base metal 39. When this central tip is observed through the surface of the arc 43, it can be seen that plasma of about 0.3 mm in diameter is generated at the center of the arc, which is found in normal Teig welding and has a diameter of about 10 mm.

This plasma 47 is about 50A at a low potential of about 35V.
This is generated simply by applying three-phase AC power with a current of A total of six arcs overlap between each electrode and the base metal 39, and an extremely high temperature arc atmosphere is generated at the center of the Teig torch 37's arc. This is thought to be because the argon gas is focused and electrolytically decomposed.

The electric circuit diagram in the embodiment shown in FIGS. 2 and 3 is as shown in FIGS. 4 and 5. , 33, and the neutral point 0 of a three-phase Y-connected power source 49 is connected to the base material 39, thereby generating an interphase arc 41 and an arc 43, thereby generating a plasma arc 47.

As can be understood from the above description of the embodiments, in short, according to the present invention, each arc generated between each of a plurality of electrodes and between each electrode and a base material is partially removed at the center of the electrode group. They overlap each other to form a high-temperature arc atmosphere in the center that is extremely hot compared to the normal arc on the outside, and supply argon gas to this high-temperature arc atmosphere to generate a plasma arc in the center of the electrode group. Therefore, even if it is not a special plasma welding machine or the like, but a normal multi-tag welding machine, the plasma It can easily generate an arc. Therefore, a plasma arc can be easily generated without requiring a complicated mechanism as in the prior art.

By the way, Figure 6 shows a reference example.
In the figure, a case is shown in which plasma solution is performed using six phases and six electrodes, and the neutral point 0 of the six-phase AC power source 51 is connected to the hollow center electrode 55 arranged in the center of the Teigu torch 53. Six welding rods 57 are arranged concentrically with the center electrode 55 in a circle around the center electrode 55 with the tips of each electrode very close to each other so that the distance between them and each other is about 1 mm, Each phase output voltage of the six-phase AC power source 51 is applied to each of these welding rods 57, respectively. In such a reference example, when a gas that is likely to generate plasma from the hollow hole of the center electrode 55, for example a gas mixed with hydrogen, etc., is ejected from the Teigue torch 53, six welding rods 57 arranged outside the center electrode 55
Arcs generated between each other, arcs generated toward the base metal (not shown), and 18 arcs of 6 phases generated toward the six welding rods 57 and the center electrode 55. I decided to do it,
A portion of these arcs is focused at the center and becomes extremely hot, generating plasma.

In addition, in the above reference example, as shown in the reference example of FIG. By adding , plasma generation becomes more powerful and stable.

As another reference example, as shown in FIG. 8, a three-phase AC power source 65 is used to generate three-phase, three-electrode multi-electrodes in a circular pattern around a pipe-shaped center electrode 67 at approximately equal intervals (approximately 1 mm intervals). ) nine tungsten electrode rods 69 provided close to each phase A, B,
When a three-phase AC voltage is applied to groups C, nine arcs generated between the tungsten electrode rods 69 are focused at the center near the center electrode 67, and are further connected to the base material (not shown) and the three-phase AC power source. A total of 10 arcs are generated by applying a voltage to the neutral point 0 of 65, which is focused at the center and becomes plasma, as in the reference example already mentioned.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram showing the torch part in the conventional plasma welding method, Fig. 2 is a plan cross-sectional view of an embodiment illustrating the discharge state of the electrode near the nozzle opening, and Fig. 3 is also a vertical cross-section. Figure, 4th
5 and 5 are electrical circuit diagrams of the embodiments shown in FIGS. 2 and 3, and FIGS. 6, 7, and 8 show electrical circuits when the number of electrodes and the number of phases of the power supply are changed, respectively. FIG. 3 is a diagram showing a reference example of a circuit. 29, 31, 33... non-consumable electrode, 35...
Gas cup, 38... Nozzle opening, 39... Base material,
41... Arc, 47... Plasma arc.

Claims (1)

[Claims] 1. The mutual spacing between the plurality of non-consumable electrodes 29, 31, 33 provided in parallel to each other in the gas cup 37 is determined by each arc 41 generated between each electrode 29, 31, 33 and each electrode 29, 31. , 33 and base material 3
9, each arc 43 generated between each electrode 2
Each of the electrodes 29,
31, 33 and each electrode 29, 31, 3
3 and the base material 39 to apply a multi-phase AC voltage between each electrode 29, 31, 33 and each electrode 2.
Arcs 41, 43 are generated between each of the arcs 9, 31, 33 and the base metal 39, and each arc 4
1 and 43 are overlapped with each other in the central part of the electrode groups 29, 31, 33.
A plasma arc generation method characterized by forming a high temperature arc atmosphere in the center of the plasma arc 47, and generating a plasma arc 47 by feeding argon gas into the high temperature arc atmosphere.