JPS6326632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a welding wire feeding control device that includes:
At the start of welding, when the contact of the relay for controlling the wire feed motor closes, the motor starting current is not allowed to flow at the same time, and a time delay is set between the closing of the relay contact and the wire feed motor rotation speed command signal for controlling the motor. It is intended to be applied to the gate circuit of a thyristor.

Conventionally, there is no particular time delay between the relay closing and the application of the wire feed command signal, and therefore, as shown in Figure 1a and b, the wire feeding starts almost at the same time as the relay contact is closed. The problem was that the starting current of the supply motor flows through the relay contacts, causing a bouncing (chattering) phenomenon of the relay contacts, shortening the life of the relay contacts.

The present invention has been made in view of such conventional problems, and a welding wire feed control device according to the present invention will be described below with reference to the drawings of FIGS. 2 and 3.

FIG. 2 shows a welding wire feeding control device according to an embodiment of the present invention, in which 1 is a wire feeding motor, and 2 is this wire feeding motor 1.
a motor control thyristor connected in series with 3
a and 3b are relay contacts that open and close in synchronization with commands to stop and start welding, 4 is a gate circuit for the motor control thyristor 2, 5 is a power supply circuit, 6 is a wire feed command signal circuit, and 7 is a PNP type The transistor 7 has an emitter connected to the wire feeding command signal circuit 6 and a collector connected to the gate circuit 4. 8 is a resistor whose one end is connected to the base of transistor 7, 9 is a capacitor connected between the emitter and base of transistor 7, and 10 is a Zener diode connected in parallel to capacitor 9. , a capacitor 9, and a Zener diode 10 constitute a signal delay circuit.

In the circuit shown in FIG. 2, when the relay contacts 3a and 3b for controlling the wire feeding motor are open, the command signal from the wire feeding command signal circuit 6 is transmitted to the motor because the transistor 7 is OFF. It is not transmitted to the gate circuit 4 of the control thyristor 2. On the other hand, at the start of welding, relay contacts 3a, 3
When b is turned on, the base current of transistor 7 flows, so transistor 7 turns on and the command signal from wire feed command signal circuit 6 is transmitted to gate circuit 4. At this time, capacitor 9 and resistor 8, the transistor 7 turns on with a time delay from the relay contacts 3a and 3b, and transmits the command signal from the wire feed command signal circuit 6 to the gate circuit 4. As a result, the command signal is transmitted to the gate circuit 4 after the path of the motor control thyristor 2, wire feeding motor 1, and relay contact 3a of the motor current circuit is formed. That is, as shown in FIG. 3a, the command signal (FIG. 3b) is transmitted to the collector of the transistor 7 after a time delay of Tw after the relay is turned on, so that the bouncing (chattering) when the relay is turned on is transmitted to the collector of the transistor 7. It is possible to make a time difference between the motor starting current (FIG. 3c) and the time when the motor is energized.

Note that the Zener diode 10 is used to charge the capacitor 9 with a constant voltage regardless of the magnitude of the command signal, and to turn on the transistor 7 with a constant time delay after the relay contact 3b is closed. be. With this Zener diode 10, the appropriate third
The Tw shown in the figure can be realized.

As described above, according to the present invention, without impairing the original function of controlling the rotational speed of a welding wire feed motor using a thyristor, it is possible to control both the balancing (chattering) phenomenon when the relay is turned on and when the motor starting current is applied. By setting a time difference, it is possible to prolong the life of the relay contact at a low cost, and by the action of the Zener diode, it is possible to ensure a uniform time difference from the motor's low speed range to the high speed range.
A high-quality, low-cost welding wire feed control device can be provided.

[Brief explanation of drawings]

1a and 1b are signal waveform diagrams for explaining the operation of a conventional welding wire feeding control device, FIG. 2 is an electric circuit diagram of a welding wire feeding control device according to an embodiment of the present invention, 3a to 3c are signal waveform diagrams for explaining the operation of the welding wire feeding control device of the present invention. DESCRIPTION OF SYMBOLS 1...Wire feed motor, 2...Motor control thyristor, 4...Gate circuit, 6...Wire feed command signal circuit, 7...Transistor, 8...
Resistor, 9... Capacitor, 10... Zener diode.

Claims (1)

[Claims] 1. Continuity between the motor control thyristor connected to both ends of the power supply circuit, the wire feeding motor, and a series circuit consisting of a first relay contact that opens and closes in synchronization with commands to stop and start welding, and the motor control thyristor. a gate circuit for controlling the wire feeding motor; a wire feeding command signal circuit for outputting a signal instructing the amount of wire fed by the wire feeding motor; and an emitter terminal connected to the output terminal of the wire feeding command signal circuit; A PNP transistor whose collector terminal is connected to the input terminal of the gate circuit, a Zener diode whose cathode terminal is connected to the emitter terminal of the transistor, and whose anode terminal is connected to the base terminal of the transistor; A welding wire feeding control device comprising a series circuit comprising a capacitor connected to the transistor, a resistor connected to the base terminal of the transistor, and a second relay contact that opens and closes in synchronization with commands to stop and start welding.