JPS6219407Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a power supply device for an automatic welding machine equipped with a wire feeding motor.

FIG. 1 is a block diagram of a conventional power supply device for an automatic welding machine. The output of the first switching circuit 2 which receives the commercial frequency power supply 1 as input is sent to the welding load 6 via the main transformer 3, the rectifier circuit 4, and the smoothing reactor 5.
is supplied to The welding load 6 is an arc generated between the base metal 60 and the welding wire 61, and its output is controlled by a volume 70 of a welding output control circuit 7 connected to the first switching circuit 2. The welding wire 61 is fed by a wire feeding roller 62 that is interlocked with the welding wire feeding motor 8. Electric power is supplied to the welding wire feeding motor 8 via a commercial frequency power supply 1, an auxiliary transformer 9, a second switching circuit 10, and a switch _S1 , and the rotation speed is determined by the second switching circuit 10.
The motor drive control circuit 11 is controlled by the volume 110 of the motor drive control circuit 11 connected to the motor drive control circuit 11 . Further, the welding output control circuit 7 and the motor drive control circuit 11 each have switches S ₄ and S ₅ for starting, and these operate in conjunction with each other. In addition, the motor drive control circuit 11
has an inching switch _S6 for inching the welding wire 61 (hereinafter referred to as inching). And, at both ends of the wire feeding motor 8,
A switch S ₂ and a resistor R for performing dynamic braking are connected.

In the above configuration, when the commercial frequency power source 1 is first input, drive voltages are applied to the welding output control circuit 7 and the motor drive control circuit 11, respectively. However, at this point, the first switching circuit 2, the second
The switching circuit 10 does not operate. Therefore,
In order to set the gap between the base material 60 and the welding wire 61, when the inching switch _S6 is lightly pressed and released, the second switching circuit 10 is driven only while the inching switch _S6 is in contact, and the switch _S1 is activated. When it is closed, the wire feeding motor 8 rotates and the welding wire 61 is fed out. Then, when the gap between the base metal 60 and the welding wire 61 is set by operating the inching switch _S6 , the interlocking switches _S4 and _S5 are turned on. When the switches _S4 and _S5 are closed, the first and second switching circuits 2,
10 is driven, power specified by volumes 70 and 110 is supplied to the welding load 6 and the welding wire feeding motor 8, respectively, and welding work is started.

In this way, conventional automatic welding power supplies
The main transformer 3 supplied power to the welding load, and the auxiliary transformer 9 supplied driving power to the wire feeding motor.

However, in such a power supply device, since power is supplied from the auxiliary transformer to the welding wire feeding motor during welding work, the auxiliary transformer needs to have a rated capacity greater than the motor capacity. For this reason, the auxiliary transformer has become considerably large, and the power supply apparatus has been disadvantageously increased in size and cost.

This idea was made in view of the above drawbacks,
The purpose of the present invention is to provide a power supply device for an automatic welding machine that can reduce the size and weight of an auxiliary transformer by simply adding a simple circuit.

To summarize this idea, a motor drive control circuit is provided that extracts part of the output of the main transformer and supplies it to the welding wire feed motor during welding, and during welding when the motor needs to be driven frequently, , so that the motor drive power is taken out from the main transformer,
The auxiliary transformer is designed to be used only during inching.

Examples of this invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a power supply device for a DC arc welding electrode type automatic welding machine, which is an embodiment of this invention. Components that are the same as or corresponding to those of the conventional automatic welding machine power supply device shown in FIG. 1 are given the same numbers.

The first switching circuit 2 includes a full-wave rectifier bridge 20, a smoothing capacitor 21, and push-pull connected switching transistors 22 and 23.
This is a well-known inverter circuit consisting of: The rectifier circuit 4 includes diodes 40 and 41 and the main transformer 3.
This is a center-tap type full-wave rectifier circuit consisting of a center-point tap. A second switching circuit 1 that switches the outputs of the diodes 40 and 41
0 is a so-called chopper circuit, which includes a diode 101 for preventing backflow to the rectifier circuit 4, a smoothing capacitor 102, a switching transistor 103 for turning on and off the output of the rectifier circuit 4, and a protection diode 104 during dynamic braking. Consisting of This second switching circuit constitutes a motor power supply circuit that supplies power to the motor 8. The transistor 103 has a base connected to the motor drive control circuit 11.
The on/off cycle is determined by the volume 110. The output of the auxiliary transformer 9 which receives the commercial frequency power supply 1 as input is a full-wave rectifier bridge 12,
The inching switch S ₆ is connected to the output of the second switching circuit 10 via a current limiter Z consisting of a suitable impedance element and limiting the starting current.

Next, the operation will be explained.

First, when the commercial frequency power supply 1 is input, drive voltages are given to the welding output control circuit 7 and the motor drive control circuit 11, respectively, and the full-wave rectification bridge 1
2 outputs a pulsating flow. However, at this point, the first
The switching circuit 2 and the second switching circuit 10 do not operate, and the output of the full-wave rectifier bridge 12 is not supplied to the wire feeding motor 8 because the inching switch _S6 is not closed. Therefore, when the inching switch S ₆ is closed to adjust the gap between the base metal 60 and the welding wire 61, the switch S ₁ is also closed in conjunction with the switch S ₆ , and power is supplied to the wire feeding motor 8, which welds. The wire 61 is sent out as the wire feeding roller 62 rotates. When inching switch S ₆ is released, switch S ₁ is opened and switch S ₂ is closed, and wire feeding motor 8 is
is operated as a generator, and the feeding of the welding wire 61 is abruptly stopped. Note that since the inching operation of the welding wire 61 is an extremely short-time operation,
As far as the power supply required for the inching operation is concerned, the rated capacity required of the auxiliary transformer 9 may be small.

By inching, the base metal 60 and welding wire 61
Once the gap is set and welding preparations are completed,
Interlocking switches S ₄ and S ₅ are turned on and welding work begins. When the switches S ₄ and S ₅ are closed, the first and second switching circuits 2 and 10 are driven, and the switch S ₁ is also closed, and the output of the main transformer 3 is used to control the welding load 6 and the wire feeding motor. Power is supplied to 8. Output control of the welding load 6 is performed by a volume 70 of the welding output control circuit 7. The feeding speed of the welding wire 61 during welding work is determined by the volume 11 of the motor drive control circuit 11.
Controlled by 0. Note that the wire feeding motor 8 is driven at a constant speed by constant voltage control by a motor drive control circuit 11. Although not shown, the motor drive control circuit 11 is a known chopper control circuit for feedback control that includes an operational amplifier, a comparator, and the like.

On the other hand, when the welding work is completed, switches S ₄ and S ₅
is turned off. Then, as in the case of inching, switch S ₁ is opened and switch S ₂ is opened.
is closed, dynamic braking is performed, and the wire feeding motor 8 suddenly stops. Thus, the wire feeding motor 8 receives power from the auxiliary transformer 9 during inching, and receives power from the main transformer 3 via the second switching circuit 10 during welding. Therefore, the auxiliary transformer only needs to supply power to the wire feeding motor 8 at the time of startup or failure, and the time required for this is extremely short. For this reason,
The auxiliary transformer 9 only needs to have the capacity necessary for the inching operation, and as a result, its size and weight can be significantly reduced compared to the conventional one.

In the above embodiment, a melt electrode type MIG welding power supply device was described, but this invention is applicable to a non-melter type MIG welding power supply device.
It can also be applied to TIG welding power supply equipment. Furthermore, this invention can be implemented in a power supply device for a semi-automatic welding machine that automatically only feeds the welding wire and manually controls the progress of welding.

As mentioned above, this invention extracts a part of the output of the main transformer during welding and supplies it to the welding wire feeding motor, and the auxiliary transformer is used to supply power only during inching operation. This has the advantage that the rated capacity of the auxiliary transformer can be significantly reduced, and it can also be made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional power supply device for an automatic welding machine, and FIG. 2 is a block diagram of a power supply device for an automatic welding machine which is an embodiment of this invention. DESCRIPTION OF SYMBOLS 1... Commercial frequency power supply, 2... First switching circuit, 3... Main transformer, 6... Welding load, 60
... Base material, 61 ... Welding wire, 7 ... Welding output control circuit, 8 ... Wire feeding motor, 9 ... Auxiliary transformer, 10 ... Second switching circuit (chopper circuit), 11 ... ...Motor drive control circuit.

Claims (1)

[Scope of utility model registration request] A switching element that switches the power supply voltage, a main transformer whose switching output is supplied to the primary side and whose secondary output is supplied to the welding load, a welding wire feeding motor, and an auxiliary whose primary side is connected to the power source. a transformer; an inching switch connected to the secondary side of the auxiliary transformer and supplying the secondary side output of the auxiliary transformer to the welding wire feeding motor when turned on; and the main transformer; A power supply device for an automatic welding machine, comprising: a motor power supply circuit connected between the output of the welding wire feeding motor and the welding wire feeding motor; and a switch that turns on and off the operation of the switching element and the motor power supply circuit. .