JP3287164B2 - DC high voltage generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact ignition type arc welding machine using a DC high voltage which can increase the allowable parallel impedance of an output terminal and achieve both safety, such as a water supply for cooling a torch, and a plasma cutting machine. The present invention relates to a direct-current high-voltage generator suitable for use in applications such as:

[0002]

For BACKGROUND ART arc welding machine or a non-contact point DC high voltage generator and the principles for arc plasma cutting machine or the like will be described with reference to FIG. 6 and FIG. 7. 1 is a DC high voltage power supply, 5 is a droop resistance,
6 and 7 represent the electrode and the base material. 8 is the distributed capacity of the output cable.

At the time of starting, about 4.5 k is applied between the electrode 6 and the base material 7.
A DC high voltage of V is applied to charge the distributed capacitance 8. When the discharge conditions are satisfied, a discharge current I ₀ having a peak of about 10 A and a pulse width of about 1 μs flows to the output. When I ₀ flows, the output voltage of the DC high-voltage power supply 1 droops by the drooping resistor 5,
The discharge stops because the voltage drops to almost 0V. Next, the recharge of the distributed capacitor 8 is started via the drooping resistor 5, and when the distributed capacitor 8 is charged to the re-ignition voltage or more, the discharge current I ₀ flows again. This process is repeated to obtain a discharge waveform as shown in FIG.

[0004]

In an arc welding machine, a plasma cutting machine, or the like, a water resistance 9 (see FIG. 6) is often arranged at an output end in order to cool an electrode. Therefore, using the drooping DC high voltage generator shown in FIG. 3A, an impedance of about 5 MΩ (6 mmφ5
In the case of a water load (when a hose of m is used), the firing rate becomes zero. Therefore, the value of the drooping resistance 5 is reduced and FIG.
When the output characteristic of B is used, the discharge frequency sharply increases,
As shown by the dotted line C in FIG. 5, the effective discharge current increases, and the danger when the human body touches the electrode by mistake increases.
There was a problem that it was difficult to realize a large current machine for thick plates by water cooling.

The present invention has been made in view of the above problems, and has as its object to enhance safety.

[0006]

According to the present invention, in order to solve the above-mentioned problems, a capacitive load is connected between output terminals, and output is stopped for a predetermined time triggered by discharge timing of the charge / discharge circuit. It has a timer circuit.

[0007]

In an arc welding machine or a plasma cutting machine equipped with the above-mentioned DC high voltage generator, even if a parallel impedance such as water resistance is connected to the output, a voltage of a level capable of maintaining discharge is maintained while maintaining safety. it can. That is, it is possible to realize an arc welding machine or a plasma cutting machine that can achieve both a parallel allowable impedance and safety, and it is easy to deal with a large current machine for a thick plate.

[0008]

FIG. 1 shows an example of a circuit configuration according to an embodiment of the present invention. 1, 6, 7, 8, and 9 are the same as those in FIG.
Reference numeral 2 denotes a capacitive load, and reference numeral 3 denotes a timer circuit that operates by using the discharge timing of the capacitive load 2 as a trigger and stops the output of the DC high-voltage power supply 1 for a certain period of time. Reference numeral 4 denotes a contact that opens and closes the output of the DC high-voltage power supply 1 in synchronization with the timer circuit 3.

Here, FIG. 4 is a characteristic diagram of the firing rate with respect to the parallel load impedance, and the allowable parallel impedance which can secure the firing rate of 80% or more is greatly expanded from about 50 MΩ of the conventional machine shown in FIG. and, in order to more 1MΩ as shown by B in FIG. 4, when the droop of the output static characteristics to reduce the resistance value of the droop resistor 5 as small as B in FIG. 3, indicated by a dotted line C in FIG. 5 Thus, the maximum of the effective value of the spark discharge current exceeds the safe value. Therefore, in the present invention, the intermittent operation of the DC high-voltage power supply 1 is performed, and the effective value of the spark discharge current is suppressed to less than that of the conventional device. FIG.
In the figure, A indicates the characteristics of the conventional machine, and B indicates the characteristics of the present invention.

Next, the intermittent operation of the DC high voltage power supply will be described with reference to FIGS. At the time of no load, the capacitive load 2 is charged only, and the discharge current id does not flow. Therefore, the timer circuit 3 does not operate, and the switch 4 remains ON. Next, when a spark discharge is started between the electrode 6 and the base material 7, the id flows and the timer circuit 3 operates by using the trigger as a trigger, the switch 4 is opened for a certain time (TOFF), and the operation of the DC high voltage power supply 1 is stopped. I do. After a certain period of time, the switch 4 is closed again, the DC high-voltage power supply 1 resumes operation, and starts spark discharge. Then, when spark discharge occurs, the timer circuit 3 operates again, the switch 4 is opened, and the DC high-voltage power supply 1 stops operating. By repeating the above, intermittent spark discharge is obtained.

[0011]

As is clear from the above description, even if a water resistance (about 5 MΩ) for cooling the electrode is provided at the output, the resistance of FIG.
As shown in FIG. 5, a perfect arc start rate can be obtained, and safety can be compatible as shown in FIG. Therefore, in an arc welding machine or a plasma cutting machine that performs non-contact ignition by a DC high voltage, the safety can be maintained and the electrode can be water-cooled, so that a large current machine for thick plates can be easily realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an arc welding machine and a plasma cutting machine using a DC high voltage generator according to one embodiment of the present invention.

FIG. 2 is an operation waveform diagram of each unit in FIG.

FIG. 3 is a comparison diagram of output static characteristics between the present invention and a conventional machine.

FIG. 4 is a characteristic diagram showing correlation data between a parallel load impedance and a firing rate in the present invention and a conventional machine.

FIG. 5 is a characteristic diagram showing correlation data between a distance between electrode base materials and a spark discharge current in the present invention and a conventional machine.

FIG. 6 is a configuration diagram of a conventional arc welding machine and a plasma cutting machine using a DC high voltage generator.

FIG. 7 is an operation waveform diagram of each unit in the conventional machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC high voltage power supply 2 Capacitive load 3 Timer circuit 4 Switch 5 Droop resistance 6 Electrode 7 Base material 8 Distribution capacity 9 Water resistance

Continuing on the front page (72) Inventor Kazuo Kimoto 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Yoshiro Tanaka 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-57-168772 (JP, A) 1979-43375 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/073 B23K 10/00 H02M 9/00

Claims (1)

(57) [Claims] 1. A DC high-voltage generator comprising: a timer circuit for connecting a capacitive load between output terminals and stopping output for a predetermined time triggered by discharge timing of the capacitive load.