JPS58205678A - Arc welding machine - Google Patents

Abstract

PURPOSE:To realize an arc welding machine in which the arc is stabilized and each element in the circuit is easily protected at the time of switching, by connecting in parallel a circuit in which two thyristors are connected in parallel but reverse direction with a series circuit of a welding arc and reactor. CONSTITUTION:In an arc welding machine which uses an AC as its output, two thyristors 21 and 22 are connected with each other in parallel but reverse direction and the connected thyristors 21 and 22 are connected in parallel with a series circuit consists of a reactor 14, electrode for welding 15, welding arc 16, base material 17, and shut 20. A transistor 12 remains turned on until the electric current of reverse polarity reaches the upper limit value by the constant- current control of a controlling circuit 23 according to the electric current detected by the shunt 20. When the current reaches to the upper limit value, the transistor 12 is turned off and the energy accumulated in the reactor 14 is discharged through the thyristor 21 and the welding arc 16 is maintained. When the discharged electric current reaches to the lower limit value, the transistor 12 is turned on and the thyristor 21 is turned off. When such circuit is used, an AC output can be supplied to the welding arc 16 under a stable condition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc welding machine that outputs alternating current.

A conventional arc welding machine that outputs alternating current is of a basic type in which the secondary output of a welding transformer having an output adjustment function is directly supplied to the welding arc, as shown in FIG. In FIG. 1, 1 is an AC power source, 2 is a welding transformer, 3 is a base material, 4 is a welding electrode, 6 is a welding rod, and 6 is an arc.

However, with this conventional arc welding machine, it is not easy to adjust the output, the output AC frequency depends on the power supply commercial frequency V, and at the same time, the output voltage waveform is a sine wave, so there is no steep rise when the polarity is reversed, and this Therefore, there was a drawback that problems such as re-ignition of the welding arc occurred.

There is also an arc welding machine that uses an AC switching regulator circuit using a flywheel diode, as shown in FIG. In FIG. 2, 1° is a DC power supply for reverse polarity, and 11 is a DC power supply for positive polarity. It is connected to a series circuit consisting of a reactor 14, a welding electrode 15, a welding arc 16, and a base material 17 via. 18 and 19 are diodes.

In this arc welding machine, the energy stored in the reactor 14 is discharged via the DC power supply 11 and the diode 19, or via the diode 18 and the DC power supply 1o, but the high voltage switching voltage In order to supply a discharge current that can maintain the welding arc 16 without generating it, the DC power source 10.11 must have a sufficiently low impedance in the direction of the discharge path.
It was actually difficult.

The present invention solves these conventional drawbacks, and includes an AC switching regulator type arc welding machine.
Two thyristors are connected in anti-parallel to the series circuit with the welding arc handler [By connecting the circuits in parallel, we aim to stabilize the welding arc, and also protect each element in the circuit from the voltage generated during switching. (It is something to protect.

FIG. 3 shows an arc welding machine according to an embodiment of the present invention, and in FIG. 3, 10 to 19 are the same parts as in FIG. 2. 20) A shunt connected in series to the Mari Altor 14, 21.22 is a thyristor, and this thyristor 21
．． 22 are connected in antiparallel to each other, and reactor 1
4, it is connected in parallel to a series circuit consisting of a welding electrode 15, a welding arc 16, a base material 17, and a shunt 2o.

A control circuit 23 controls the operation of the transistor 12.13 and the thyristor 21.22 in accordance with the current detected by the shunt 2o.

That is, the energy stored in the reactor through the transistor 12.13 is transferred to the 0FFI of the transistor 12.13 through the thyristor 21 or the thyristor 22.
, it is also supplied when

Figure 4a-e shows the circuit 2 that controls the output of the shunt 2o.
3 shows waveforms at various parts when the control circuit 23 is used as a constant current circuit.

In FIG. 4, at the start of the period TRP for supplying an output of reverse polarity to the welding arc 16, a gate signal vGRP'r: is supplied to the gate of the thyristor 21, and when the thyristor 21 is forward biased, it becomes conductive. .

Due to the constant current control function of the control circuit 23, the transistor 12 is turned on until the reverse polarity current reaches the set upper limit value RPP. As soon as the transistor 12 reaches "RFP," the energy stored in the reactor 14 is discharged via the thyristor 21 and the welding arc 16 is maintained. When the voltage falls, the transistor 12 is turned on again by the action of the control circuit 23. As a result, the thyristor 21 is turned off even though it is reverse biased and is supplied with the gate signal vGRP. In this way, during the reverse polarity output supply period TRP, constant current control is performed by repeatedly turning ON and OFF the transistor 12.

Therefore, the energy stored in the reactor 14 is discharged via the thyristor 21, so that the welding arc 16 is maintained without generating a high voltage.

During ΔTRP before the end of the reverse polarity application period TRP, the gate signal vG of the thyristor 21 is controlled by the function of the control circuit 23.
RP is set to 0FFL, the transistor 12 is turned on, the thyristor 21 is forcibly turned off, and the positive polarity is applied for a period T.
Move to sp. At this time, the voltage generated in the reactor 14 is absorbed via the positive polarity DC power supply 11 and the diode 19.

During the positive polarity application period T8P, the energy accumulated in the reactor 14 due to the same redness is discharged. i.e. % V at the gate of thyristor 22 with the start of TSP. By applying a gate signal of 8P, the transistor 13
provides a positive polarity output, and the set current upper limit value is
Increase to pp. After reaching "spp", the transistor 13 turns off, and the energy stored in the reactor 14 is discharged by the thyristor 22, lowering it to the set lower limit value SPH and maintaining the welding arc 16.

At ΔTsP before the end of the IE polarity application period Tsp, the gate signal V of the thyristor 22 is applied. 8P is turned off, transistor 13' is turned on, and thyristor 22 is reverse biased and turned off. At this time, the voltage generated in the reactor 14 is absorbed via the diode 18 and the reverse polarity DC power supply 1o.

With the above operation, the circuit shown in Figure 3 can stably weld arc 1.
Supply all AC output to 6. Note that FIGS. 4 and 4 d are operating waveforms of the transistors 12 and 13, respectively.

As described above, according to the arc welding machine of the present invention, AC output can be supplied to the welding arc regardless of the power supply commercial frequency, and the energy accumulated in the reactor can be efficiently returned to the welding arc to stabilize the welding arc. Therefore, the voltage generated by switching can be lowered, and the element can be easily protected.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of a conventional arc welding machine, FIG. 3 is a circuit diagram of an arc welding machine according to an embodiment of the present invention, and FIGS. 4a to 4e are circuit diagrams of the circuit of FIG. 3. FIG. 10.11...DC power supply, 12.13...
River/Rangista, 14...Reactor, 16...
...Welding arc, 21. 22... Thyristor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure/? Figure 2 Figure 3 Procedural Amendment (Method) February 240, 1980 Director General of the Patent Office 1 Display of the case 1989 Patent Application No. 89120 2 Name of the invention Arc welding machine 3 Whether to arrest or not 1 “North;y, q!,” with 1:
Permission Application Address: 1006 Kadoma, Kadoma City, Osaka J-2 (582) Matsushita Electric Industrial Co., Ltd. Representative 6 111 Toshihiko Shimo 4
Agent Address: 7, Matsushita Electric Industrial Co., Ltd., 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture, 571, Amended "Figures 4 a to e" on page 8, line 8 of the statement of amendment to "Figure 1 Figure 4" There was (-masu.

Claims (1)

[Claims] A reverse polarity DC power source is connected to the series circuit with the welding arc handler through a first transistor, and a positive polarity DC power source is connected to the series circuit through a second transistor, and the series circuit an anti-parallel circuit of first and second thyristors, wherein the cathode of the first thyristor is connected to the positive side of the DC power source for reverse polarity, and the cathode of the second thyristor is connected to the positive side of the DC power source for positive polarity. When connecting in parallel to provide reverse polarity output,
A gate signal is supplied to the gate of the first thyristor at the start of the supply, and the gate signal is supplied to the gate of the first thyristor before the supply of the reverse polarity output ends.
The supply of the gate signal to the gate of the thyristor is stopped, and the first transistor is turned on to turn off the first thyristor, and when supplying a positive output, the supply is started and the second thyristor is turned off. supplying a gate signal to the gate, stopping the supply of the gate signal to the gate of the second thyristor before the supply of the reverse polarity output ends, and turning on the second transistor;
Arc welding machine 0 characterized in that the second thyristor is turned off by