JPH039894Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a multi-electrode TIG welding device that welds a welded portion of a base material using a plurality of electrodes.

[Prior art]

Conventionally, multi-electrode TIG welding equipment, for example,
It is configured as shown in the figure, and 1 is a Δ-connected primary winding. Connection points 2a to 2c of the first to third windings 1a and 1c are connected to a three-phase AC power source. The transformers 3a to 3c are the fourth to sixth windings 1 whose cathodes are the secondary windings of the transformer 1, respectively.
1st to 3rd diodes connected to d to 1f, 3
b to 3f are connected to the anodes and cathodes of the first to third diodes 3a to 3c, respectively;
A three-phase full-wave rectifier circuit 3 is configured together with the diodes 3a to 3c.

4 has both ends the anodes of the first to third diodes 3a to 3c and the fourth to sixth diodes 3d to 3f.
5 is an NPN whose emitter is connected to one end of capacitor 4.
6 is a current detector whose one end is connected to the collector of regulator 5 and which detects the welding current and outputs a detection signal from the detection signal output terminal; 7 is a detector whose detection signal input terminal is connected to the collector of regulator 5; This is a control circuit connected to the detection signal output terminal of the regulator 5, and outputs a base control signal to the base of the transistor of the regulator 5.
A low frequency control signal of several 100 Hz is output to the bases of first and second switching transistors, which will be described later.

Emitters 8 and 9 are connected to the other end of the detector 6 and are switched by the low frequency control signal.
NPN type first and second switching transistors (hereinafter referred to as first and second transistors), 10, 1
1 is the first and second transistors 8 and 9 at one end, respectively.
first and second coupling coils connected to the collector of the
12 and 13 are first and second TIG welding torches connected to both coupling coils 10 and 11, respectively.
The electrode 14 is a base material, which is connected to the cathodes of the fourth to sixth diodes 3d to 3f, and each connection portion of the base material 14 is welded by both electrodes 12 and 13, respectively.

When welding the base material 14, the transistor of the regulator 5 is turned on by the base control signal output from the control circuit 7, and a low frequency control signal of several 100 Hz is output from the control circuit 7 to the base of the first transistor 8. As shown in FIG. 2a, the first transistor 8 is repeatedly turned on and off.
During the ON period of the first transistor 8, the current from the rectifier circuit 3 flows through the rectifier circuit 3, the base material 14, and the first electrode 1.
2, an arc is generated between the first electrode 12 and the base material 14 through a series circuit consisting of the first coupling coil 10, the collector and emitter of the first transistor 8, the detector 6, the regulator 5, and the rectifier circuit 3. , the filler metal is melted and the welded portion of the base metal 14 is welded by the first electrode 12.

Next, a low frequency control signal having a waveform obtained by inverting the low frequency control signal sent to the first transistor 8 is outputted from the control circuit 7 to the base of the second transistor 9, and as shown in FIG. transistor 9
is repeatedly turned on and off, contrary to the on and off operations of the first transistor 8, and during the on period of the second transistor 9, that is, the off period of the first transistor 8, the current from the rectifier circuit 3 flows into the rectifier circuit 3, the motherboard. Material 1
4, second electrode 13, second coupling coil 11, collector and emitter of second transistor 9, detector 6,
The arc flows through a series circuit consisting of the regulator 5 and the rectifier circuit 3, and an arc is generated between the second electrode 13 and the base metal 14, and the filler metal melts to form the welded portion of the base metal 14 by the second electrode 13. Welding is performed and these operations are repeated to weld the base material 14 and both electrodes 12, 13.
A welding current of a predetermined level I as shown in FIG. Each part is welded alternately.

In addition, at the time of arc start, although not shown, a high frequency high voltage power source is connected between both coupling coils 10 and 11 and the base material 14, and the high frequency high voltage from the power source is applied to the base material 14, both electrodes 12, 13, an arc is generated between the electrodes 12, 13 and the base material 14, and welding is started.

At this time, the detector 6 detects the base material 14 and both electrodes 1.
The welding current flowing between 2 and 13 is detected and a detection signal is output to the control circuit 7, and the control circuit 7 controls the base control signal to the transistor of the regulator 5 so that the welding current is constant. The welding current flowing between the material 14 and both electrodes 12, 13 is controlled at a constant current.

In addition, since arcs are generated alternately between both electrodes 12 and 13 and the base metal 14, if an arc is generated by simultaneously applying electricity between the base metal 14 and both electrodes 12 and 13, one of the arcs will occur. The pull-in phenomenon of the other arc, that is, the interference of the arcs, is prevented, and a uniform weld bead is formed.

However, in the case of FIG. 1, the regulator 5 is composed of one transistor for simplicity.
Since the welding current is normally a large current, the regulator 5 must be constructed by installing multiple transistors in parallel, and each transistor in the regulator 5 generates heat, so a means of cooling these transistors is required. The structure becomes complicated, and since the smoothing capacitor 4 is located on the side of the current-carrying circuit to the electrodes 12, 13 and the base material 14, the capacitor 4
However, it is necessary to use a large-capacity transformer, and the transformer 1 is also large, resulting in an increase in the size of the entire device.

Further, since constant current control of the welding current is performed by controlling the base control signal of the transistor of the regulator 5, there is a drawback that the response to fluctuations in the welding current is slow and prompt control of the welding current cannot be performed.

[Purpose of invention]

This invention has been made with the above-mentioned points in mind, and aims to simplify and downsize the configuration and to perform constant current control of the welding current with good responsiveness.

[Structure of the invention] This invention includes a DC power supply, a control circuit that outputs a high frequency control signal and a low frequency control signal, and a control circuit that is connected to the power supply and switches according to the high frequency control signal to convert the DC from the power supply into high frequency AC. a high-frequency switching circuit for outputting a high-frequency switching circuit; a high-frequency transformer having a primary winding connected to the switching circuit; and a rectifier circuit connected to a secondary winding of the transformer for rectifying the high-frequency alternating current through both windings; A current from the rectifier circuit is sequentially passed between a plurality of low frequency switching elements connected to the rectifier circuit and sequentially switched in response to the low frequency control signal and the base material via each of the elements. This is a multi-electrode TIG welding device that includes a plurality of electrodes that sequentially weld the welded portions of the base metal.

[Effect of idea]

Therefore, according to the multi-electrode TIG welding device of this invention, a high-frequency switching circuit is provided which performs switching in response to a high-frequency control signal from a control circuit, and the high-frequency switching circuit performs switching via the primary and secondary windings of a high-frequency transformer. a rectifier circuit that rectifies high-frequency alternating current generated by the circuit, and a plurality of circuits that are sequentially switched in response to a low-frequency control signal from the control circuit to sequentially pass current from the rectifier circuit between the base material and each electrode. The low-frequency switching element eliminates the need for a conventional series regulator, requires a small-capacity smoothing capacitor, and eliminates the need for a large power transformer, simplifying and downsizing the configuration. can be achieved.

Furthermore, by controlling the frequency of the high-frequency control signal from the control circuit and the switching frequency of the high-frequency switching circuit, the response of constant current control to fluctuations in the welding current can be made faster, and the welding current can be adjusted with good responsiveness. Constant current control is possible.

〔Example〕

Next, this invention will be explained in detail with reference to FIG. 3 showing one embodiment thereof.

In the figure, 15 is a commercial AC power supply, 16 is a diode bridge rectifier circuit with both input terminals connected to both ends of the power supply 15 as a DC power supply for rectifying the commercial AC of the power supply 15, and 17 is a diode bridge rectifier circuit whose both ends are connected to the positive side of the rectifier circuit 16. , a smoothing capacitor connected to the negative output terminal, 1
8 outputs a high frequency control signal with a phase shift of 180 degrees to the bases of the third and fourth transistors, which will be described later, and outputs a low frequency control signal of several hundred Hz with a phase shift of 180 degrees to the bases of the fifth and sixth transistors. 19 is the third and fourth transistor 1 of NPN type.
This is a high frequency switching circuit consisting of transistors 9a and 19b, the bases of both transistors 19a and 19b are respectively connected to both high frequency control signal output terminals of the control circuit 18, and both emitters are connected to the negative output terminal of the rectifier circuit 16. The high frequency control signal causes both transistors 19a,
19b alternately turns on and off, converting the DC rectified and smoothed by the rectifier circuit 16 and capacitor 17 into high-frequency AC.

20, one end and the other end of the primary winding 20a are connected to the collectors of the third and fourth transistors 19a and 19b, respectively, and the intermediate tap of the primary winding 20a is connected to the positive output terminal of the rectifier circuit 16. The high frequency transformer 21 is composed of seventh and eighth rectifying diodes 21a and 21b, each having a cathode connected to both ends of the secondary winding 20b of the transformer 20 and an anode connected to each other. a rectifier circuit that rectifies the high frequency alternating current by the high frequency switching circuit 19 through the
22 and 23 each have a base connected to both low frequency control signal output terminals of the control circuit 18, and an emitter connected to the anode of the seventh diode 21a, and are low frequency signals that are alternately turned on and off by the low frequency control signal. It is a switching element.
The NPN type fifth and sixth transistors 24 have one end connected to the intermediate tap of the secondary winding 20b and a detection signal output terminal connected to the detection signal input terminal of the control circuit 18 to detect the welding current. A current detector that outputs a signal, 25 and 26 are third and fourth coupling coils whose one ends are connected to the collectors of the seventh and eighth transistors 22 and 23, and 27 and 28 are connected to both coupling coils 25 and 26. The third and fourth electrodes 29 made of a TIG welding torch are the base metal, and are connected to the other end of the detector 24, and each welding part of the base metal 29 is welded by both electrodes 27, 28.

Next, the operation of the above embodiment will be explained.

First, a high frequency control signal output from the control circuit 18 causes the third and fourth transistors 19a, 19
b alternately turns on and off, and during the on period of the third transistor 19a, that is, the off period of the fourth transistor 19b, the current rectified and smoothed by the rectifier circuit 16 and the capacitor 17 flows to the intermediate tap of the primary winding 20a. and one end, the collector and emitter of the third transistor 19a, and the rectifier circuit 16
At the same time, during the on period of the fourth transistor 19b, that is, the off period of the third transistor 19a, the current rectified and smoothed by the rectifier circuit 16 and the capacitor 17 flows through the intermediate tap and the other end of the primary winding 20a, and the fourth The current flows through the collector, emitter, and rectifier circuit 16 of the transistor 19b, and these operations are repeated until the high frequency switching circuit 1
9 converts the direct current into high-frequency alternating current, and the high-frequency alternating current flows through the primary winding 20a of the transformer 20.
Both windings 20 of the transformer 20 are connected by the rectifier circuit 21.
The high frequency alternating current passing through a and 20b is rectified.

Then, the fifth and sixth transistors 2 are controlled by a low frequency control signal output from the control circuit 18 to the base.
2 and 23 alternately turn on and off, and during the on period of the fifth transistor 22, that is, the off period of the sixth transistor 23, the current from the rectifier circuit 21 flows through the rectifier circuit 21, the detector 24, the base material 29, and the sixth transistor 23. 3
Flowing through a series circuit consisting of the electrode 27, the third coupling coil 25, the collector and emitter of the fifth transistor 22, and the rectifier circuit 21, an arc is generated between the third electrode 27 and the base metal 29, and the filler metal melts. ,
The on period of the sixth transistor 23, that is, the fifth
During the off period of the transistor 22, the current from the rectifier circuit 21 flows through the rectifier circuit 21, the detection circuit 24, and the base material 2.
9, the fourth electrode 28, the fourth coupling coil 26, the collector of the sixth transistor 23, the emitter, and the rectifier circuit 21. An arc is generated between the fourth electrode 28 and the base metal 29, and the filler metal melts and these operations are repeated, arcs are generated alternately between each of the electrodes 27 and 28 and the base metal 29, and a welding current of a predetermined level is continuously generated between the base metal 29 and the electrodes 27 and 28. flow, both electrodes 27 and 28 run along the welded part of base metal 29, and both electrodes 27 and 28
The welding of one welded portion of the base material 29 is performed alternately.

Incidentally, the arc start is performed by connecting a high frequency, high voltage power source in the same manner as in the case of FIG. 1 above.

At this time, the welding current flowing between the base metal 29 and both electrodes 27 and 28 is detected by the detector 24, and a detection signal is output to the control circuit 18. 3, 4th
The frequency of the high frequency control signal to transistors 19a, 19b is controlled, and both transistors 19a, 1
The on/off repetition frequency of the coil 9b, that is, the switching frequency, is controlled to control the high frequency alternating current flowing through the primary winding 20a, and the welding current is controlled to be a constant current.

Therefore, according to the embodiment described above, since the constant current control circuit and the load circuit on the primary side are separated by the transformer, the series regulator 5 described above is not required, and the capacitor 17 can be of small capacity and large. Since a capacitor is not required and the high frequency transformer 20 is smaller than the power transformer 1 described above, the structure can be simplified and downsized.

Furthermore, by controlling the frequency of the high-frequency control signal from the control circuit 18, the welding current can be controlled at a constant level, and since the switching frequency of the third and fourth transistors 19a and 19b by the high-frequency control signal is very high, the welding Excellent responsiveness to current fluctuations.

Note that this invention can be implemented in the same manner even if there are three or more electrodes.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram of a conventional multi-electrode TIG welding device, Fig. 2 a to c is a timing chart for explaining the operation of Fig. 1, and Fig. 3 is an embodiment of the multi-electrode TIG welding device of this invention. FIG. 16... Diode bridge rectifier circuit, 18... Control circuit, 19... High frequency switching circuit, 20...
High frequency transformer, 20a, 20b...primary and secondary windings, 21...rectifier circuit, 22, 23...fifth and sixth transistors, 27, 28...electrode, 29...base material.

Claims (1)

[Scope of utility model registration request] a DC power supply, a control circuit that outputs a high-frequency control signal and a low-frequency control signal, a high-frequency switching circuit that is connected to the power supply and switches according to the high-frequency control signal to output the DC from the power supply as high-frequency AC; a high frequency transformer having a winding connected to the switching circuit; a rectifier circuit connected to a secondary winding of the transformer to rectify the high frequency alternating current passing through both windings; The current from the rectifier circuit is sequentially passed between a plurality of low frequency switching elements that are sequentially switched in accordance with a control signal and the base metal through each of the elements to sequentially weld the welded portion of the base metal. A multi-electrode TIG welding device equipped with multiple electrodes for welding.