JPH0366069B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma processing apparatus that can selectively generate plasma jets or plasma arcs to a plurality of plasma processing torches.

[Conventional technology]

Plasma arcs or plasma jets are widely used for cutting or welding nonferrous metals such as aluminum and stainless steel, as well as general steel materials. When selectively generating a plasma jet or a plasma arc with one plasma processing apparatus, as shown in FIG. Switches 4' and 5' were connected between the material 2 and the main power source 3, and these switches were opened and closed to selectively generate a plasma jet and a plasma arc. Note that 6 is a normal starting power source for forming an arc between the sleeve 1a and the cathode electrode 1b when the torch 1 is started. To explain the electrical operation of this device in more detail, first, a starting power source 6 consisting of a high frequency generator and a pilot power source is operated to generate an arc between the sleeve 1a of the torch 1 and the cathode electrode 1b.
Next, the main power source 3 is activated and the switch 4' is closed, thereby generating a pilot arc between the sleeve 1a of the torch 1 and the cathode electrode 1b. By adjusting the current amount of the main power source 3 and the flow rate of plasma gas flowing through the torch 1, a desired plasma jet is generated. If it is desired to generate a plasma arc instead of a plasma jet, it is sufficient to close the switch 5' and open the switch 4'.

[Problem that the invention seeks to solve]

When a single torch is used for welding or cutting, it can be used as in the conventional example, but it is also possible to use multiple torches to simultaneously generate plasma arcs or plasma jets to weld or cut the same workpiece or different workpieces. When processing, the following problems arise.

(1) First, providing a dedicated main power source and starting power source for each torch increases the price of the entire device and increases its size and weight. In particular, when the number of torches is ten or more, these drawbacks become extremely serious in practice. Furthermore, the number of wires connecting these power sources and each torch becomes extremely large, which often causes problems in processing operations.

(2) Therefore, a configuration in which multiple torches share one main power source and starting power source is conceivable, but the state of the plasma jet or plasma arc of each torch is extremely unstable and constantly fluctuates. , it is difficult to control the energy of the plasma jet or plasma arc generated from each torch to be approximately equal. Furthermore, even if it is possible to control the energy of the plasma jet or plasma arc generated from each torch so that it is approximately equal or at a predetermined ratio, the potential between each torch or the potential of the workpiece becomes a problem, and multiple A device in which a single power source is shared by two torches has not been put into practical use, and there are no proposals for a specific configuration that can switch between the plasma jet and the plasma arc without problems.

[Means for solving problems]

This device includes a first power source whose positive output terminal is connected to the workpiece and whose negative output terminal can be connected to cathode electrodes of a plurality of torches via each switch element; a second power source connected to the sleeve of the torch and whose negative output terminal can be connected to the cathode electrode of the torch via a respective semiconductor switch element.

[Effect]

With this structure, by controlling the impedance of the semiconductor switch element, it is possible to control the energy of the plasma jet or plasma arc generated from each torch to be equal or at a predetermined ratio. Since the potentials between the sleeves and the workpieces can be made almost equal, an accident will not occur even if the torches come into contact with each other, and there is no need to insulate the workpiece from the ground. This shows that a single workpiece can be processed using multiple torches.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. 1. 3A and 3B are respectively a plasma arc power supply;
This is the power supply for the plasma jet, and the positive power supply is 3A.
The negative terminals are connected to conductors 9A and 9B, respectively, and the power supply 3
The positive and negative terminals of B are connected to conducting wires 10A and 10B, respectively. Each workpiece 2A, 2 is connected to the conductor 9A.
B, . . . , 2N are connected, and the sleeves of the respective torches 1A, 1B, . Resistors 7A and 7 are connected to the conductor 10B connected to the negative terminal of the plasma jet power supply 3B.
B, . . . , 7N, and each torch 1A, 1B, .
..., 1N cathode electrodes are connected. Conductor 9B connected to the negative terminal of plasma arc power supply 3A
include resistors 8A, 8B, . . . , 8N and semiconductor switch elements 5A, 5B, . . . such as transistors.
The cathode electrodes of the respective torches 1A, 1B, .

Next, the electrical operation of this plasma processing apparatus will be explained.

If you want to generate a plasma jet, leave all semiconductor switches 5A, 5B, ..., 5N open (off), and turn semiconductor switch 4 on.
Close A, 4B, ..., 4N. Accordingly, the voltage of the power source 3B is applied between the sleeves and cathode electrodes of the torches 1A, 1B, . . . , 1N, and an arc is generated between them, thereby forming a plasma jet. Since the plasma jet is unstable, in order to make each torch 1A, 1B, ..., 1N uniform and stable, semiconductor switches 4A, 4 are installed, respectively.
B, . . . , 4N may be controlled to adjust their impedances. At this time, resistors 7A, 7B,
..., 7N are used as current detection resistors, and semiconductor switches 4A, 4B, ... are used so that the currents flowing through the resistors 7A, 7B, ..., 7N are almost equal.
..., 4N impedances are controlled respectively.

Next, the plasma arc is applied to each torch 1A, 1B,...
..., 1N and the workpieces 2A corresponding to these,
2B, ..., 2N, close the semiconductor switches 5A, 5B, ..., 5N, and then switch the semiconductor switches 4A, 4B, ..., 4N.
open. By doing this, each torch 1
The arc discharge that was occurring between the cathode electrodes A, 1B, ..., 1N and the sleeves was caused by the cathode electrodes and the corresponding workpieces 2A, 2, respectively.
B, ..., 2N, and a plasma arc is formed. Since the plasma arc generated by each torch is generally extremely unstable, the impedance of the semiconductor switches 5A, 5B, ..., 5N is controlled and the resistors 8A, 8B, . ..., 8N, the plasma arcs generated from each torch can be made approximately equal.

Now, each torch 1A, 1B, ..., 1N
Since all of the sleeves are directly connected to the conductor 10A, it is possible that the impedances of the semiconductor switches 4A, 4B, . However, the sleeve of each torch is always at the same potential, so torches 1A, 1B,...
..., 1N will not cause an electrical short circuit problem even if any of the torches 1A, 1B,...
..., 1N can be placed in contact with each other. Similarly, since all of the workpieces 2A, 2B, ..., 2N are directly connected to the conductor 9A, the impedance of the semiconductor switches 5A, 5B, ..., 5N may be considerably different, or one of them may be Even if the workpieces 2A, 2B,...2N are in the open state,
are always at the same potential. Therefore, a single large-area workpiece can be processed with a plurality of torches, or connected workpieces can be processed independently with each torch.

Next, another embodiment of the present invention will be described with reference to FIG. 2. This embodiment uses a torch having an inner sleeve surrounding a cathode electrode and an outer sleeve, which is well known in the art. I won't explain it because there is. This plasma processing equipment has a first
Two sets of devices as shown in the figure are provided, and each set shares only the power source 11 for starting. This starting power source 11 includes common conductive wires 12A, 12B and switches 13A ₁ , 13B ₁ , which are switched sequentially, respectively.
..., 13N ₁ , 13A ₂ , 13B ₂ , ..., 13N ₂
are connected between _the cathode electrodes _{of each} torch 1A ₁ , 1B _{1 ,} . Gives you the power you need to maintain it. After activating the power supply 11 and generating an arc discharge between the inner sleeve of each torch and the cathode electrode, the semiconductor switches 4A ₁ , 4B ₁ , ..., 4N ₁ and 4A ₂ , 4B ₂ , ..., 4N ₂ By closing, an arc discharge can be generated between the outer sleeve and the cathode electrode. By configuring the power supplies 3B ₁ and 3B ₂ so that the power capacity can be switched, the arc discharge between the outer sleeve and the cathode electrode can be used as a plasma jet or a pilot arc. When it is desired to generate a plasma arc between each torch and each workpiece, the semiconductor switch 5A ₁
5N ₁ and 5A ₂ to 5N ₂ are closed, and then semiconductor switches 4A ₁ to 4N ₁ and 4A ₂ to 4N ₂ are opened.

〔Effect of the invention〕

As described above, according to the present invention, stable and substantially uniform plasma jets and plasma arcs can be selectively generated by a plurality of torches that share a power source. All sleeves can be kept at the same potential at all times, and all workpieces can also be kept at the same potential at all times, so there is no electrical short circuit between torches, and the same workpiece can be processed simultaneously with multiple torches. It has great effects.

[Brief explanation of drawings]

1 and 2 are views showing separate embodiments of a plasma processing apparatus according to the present invention, and FIG. 3 is a view showing a conventional example. 1A ₁ ~ 1N ₁ , 1A ₂ ~ 1N ₂ ... Torch, 2A ₁
〜2N ₁ , 2A ₂ 〜2N ₂ ...Work material, 3A ₁ , 3
A ₂ 3B ₁ , 3B ₂ 11...Power supply, 4A ₁ ~ 4N ₁ , 4
A ₂ ~ 4N ₂ , 5A _{1 ~} 5N ₁ , 5A ₂ ~ 5N ₂ ... Semiconductor switch, 7A ₁ ~ 7N ₁ , 7A _{2 ~} 7N ₂ , 8A ₁
~8N ₁ , 8A ₂ ~8N ₂ ...Resistance.

Claims (1)

[Claims] 1 A plurality of plasma processing torches, a positive output terminal connected to a workpiece, and a negative output terminal connected to a cathode electrode of the plurality of plasma processing torches via each semiconductor switch element. a first power source that can be connected to a first power source, the positive output terminal being connected to the outermost sleeve of the plasma processing torch, and the negative output terminal being connected to the cathode of the plasma processing torch through a respective semiconductor switch element; a second power source that can be connected to an electrode; and a plasma processing apparatus, characterized in that the outermost sleeves of each of the plasma processing torches and the workpieces are set at substantially the same potential.