JPH0818128B2 - Consumable electrode type power supply for welding - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a welding power source for automatically feeding a welding wire which is a consumable electrode to perform arc welding.

2. Description of the Related Art In this type of conventional power source for welding, wire slowdown control has been switched back at the start of welding in order to smooth the arc generation at the start of welding. The trigger signal for switching from the wire slowdown state to the steady state is generally a welding current detection signal that detects the presence or absence of welding current, or a welding voltage detection signal that detects a non-contact arc. In any case, the wire feeding speed during the welding operation was the slowdown speed or the steady welding speed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-mentioned conventional example, since it depends on the welding current detection signal or the welding voltage detection signal as a signal for switching from the slowdown condition to the steady condition, the arc due to the difference in the tip shape of the wire at the start of welding, etc. It was not possible to detect the variation in the time until the occurrence, and as a result, the wire was broken in the middle, the wire burned up, etc., and a uniform arc start state could not be obtained. Especially when it is difficult to melt due to its low specific resistance such as aluminum wire, the wire remains semi-melted and no arc is generated. In addition, due to excessive burning of the wire, an accident such as fusion of the molten wire to the current-carrying tip may occur.

Means for Solving the Problems In order to solve the above problems, the present invention, a welding current detection circuit for detecting the presence or absence of a welding current, a welding wire is short-circuited in contact with a welded object, or a welding arc is generated in a non-contact manner. A wire short-circuit detection circuit that determines whether or not and outputs a signal,
A wire output stop signal output circuit for outputting a signal for stopping the feeding of the welding wire, using the output signals of the welding current detection circuit and the wire short-circuit detection circuit as an input signal,
Output control that receives the output signal of the wire short-circuit detection circuit and the wire output stop signal of the wire output stop signal output circuit as input, and outputs a control output signal having a certain inclination to a welding wire feeding motor until a steady condition Equipped with a circuit,
While the output control circuit detects the welding current absence when the output signal of the welding current detection circuit at the arc start of the welding start, the wire feeding speed is the wire feeding speed during steady welding,
Alternatively, the signal for the slowdown speed, which is lower than that during steady welding, is output to the welding wire feed motor, and the output signal of the welding current detection circuit detects the presence of welding current, and then the wire short circuit is detected. While the output signal of the circuit detects the wire short-circuit state, the output control circuit stops the welding wire feeding motor by the output signal of the wire output stop signal output circuit, and the output signal of the wire short-circuit detection circuit is After detecting that there is a non-contact arc,
The output control circuit outputs a control signal having a certain inclination up to a steady condition to the wire feeding motor.

Function In the above configuration, when the output control circuit is in a state in which the output signal of the welding current detection circuit has a welding current at the arc start of welding start and the output signal of the wire short circuit detection circuit is in a state of contact short circuit, The output control circuit stops the wire feeding by the output of the output stop signal output circuit. Therefore, the wire feeding is stopped until the arc is detected regardless of the wire tip shape, wire diameter, wire material, etc., and the wire feeding speed changes from the stopped state to the normal welding state with a certain inclination. Therefore, the wire is sufficiently overheated and melted, and smooth and uniform arc start performance can be obtained.

Embodiments Embodiments of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is a welding power source input terminal, 2 is a welding transformer, 3 is a rectifying element, 4 is a welding output control element, 5 is a welding performance adjusting reactor, 6 is a shunt, and 7 is a welding power source. Output terminal, 8 is an energizing contact tip, 9 is a welding wire, 10 is an object to be welded, 11 is a welding arc, 12 is a wire feeding motor, 13 is an output control circuit, 14 is a welding current detection circuit,
Reference numeral 15 is a wire short circuit detection circuit, and 16 is a wire output stop signal output circuit.

The wire short-circuit detection circuit 15 is connected between the pair of welding power source output terminals, determines whether the welding output voltage is equal to or higher than a certain value, and determines whether or not the welding wire 9 is short-circuited to the workpiece 10 according to the determination result. It is determined whether or not a welding arc is generated in a non-contact manner and a signal S is output.

The welding current detection circuit 14 detects the presence or absence of welding current and outputs a detection signal A.

The wire output stop signal output circuit 16 has a detection signal A and a signal S.
Is input and the signal N is output.

The output control circuit 13 receives the detection signal A and the signals S and N,
A signal M having a certain inclination is output to the welding wire feeding motor 12 up to a steady condition.

The welding current detection circuit 14 and the wire short circuit detection circuit 15
Is composed of a comparator circuit or the like which has been often used conventionally, and the wire output stop signal output circuit 16 is composed of, for example, a microcomputer and outputs the wire output stop signal N in accordance with the programming shown in FIG.

Next, as an example of the configuration of the output control circuit, it is configured by a governor circuit for driving a motor and a microcomputer as shown in FIG. In FIG. 4, the microcomputer 17 outputs a command signal M ′ from the microcomputer 17 to the governor circuit 18 according to the programming shown in FIG. The governor circuit 18 stops its operation while the wire output stop signal N is output, and while the signal N is not output, the command signal M ′ from the microcomputer 17 to the governor circuit 18 drives the motor. It is converted into a command signal M to the motor for output and output.

Next, the operation of the above configuration will be described with reference to FIG. At the start of welding, the output control circuit 13 turns the wire feed motor 12
The output signal of the slowdown condition lower than that during steady welding is sent to. Welding wire delivered under slowdown conditions
When 12 short-circuits with the workpiece 10 (time t1 in Fig. 2),
The welding current detection signal A outputs a state with welding current. At the same time, the wire short circuit detection signal S outputs a wire short circuit state. Since the wire output stop signal output circuit 16 receives the signal with the welding current and the wire short circuit signal, the wire output stop signal N is sent to the output control circuit 13 and the command signal M to the wire feed motor 12 is the feed stop condition. Becomes By continuing these control states, the welding wire is sufficiently overheated and melted, and an arc is generated at time t2 in FIG. As a result, the wire short circuit detection signal S is inverted to the non-contact state, so the output stop signal N is turned off, and the output control circuit 13 causes the wire feeding motor.
An output signal M having a certain slope is output up to 12 under a steady condition.

EFFECTS OF THE INVENTION As is clear from the above description, according to the present invention, since the wire feeding is stopped before the arc is generated after the wire comes into contact with the object to be welded, the wire is sufficiently overheated and melted, It is possible to obtain a smooth and uniform arc start performance especially for an aluminum wire or the like without causing a buckling accident. Further, the wire feeding speed under the slowdown condition can be increased, and the time from sending the welding start signal to actually starting the welding can be shortened, so that the operating rate can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram of an essential part of FIG. 1, FIG. 3 is a flowchart for programming a microcomputer in a wire output stop signal output circuit, and FIG. Is a concrete circuit diagram of the output control circuit, and FIG. 5 is a programming flowchart of the microcomputer in the output control circuit. 9 ... Welding wire, 10 ... Welding object, 11 ... Welding arc, 12 ... Wire feeding motor, 13 ... Output control circuit, 14
...... Welding current detection circuit, 15 ...... Wire short circuit detection circuit, 16
...... Wire output stop signal output circuit.

Claims (1)

[Claims] 1. A welding current detection circuit for detecting the presence / absence of a welding current, and whether the welding wire is short-circuited in contact with the workpiece.
A wire short circuit detection circuit that determines whether a welding arc is generated in a non-contact manner and outputs a signal, an output signal of the welding current detection circuit and an output signal of the wire short circuit detection circuit as input signals, and a welding wire A wire output stop signal output circuit for outputting a signal for stopping the feeding of the welding wire, an input signal of the wire short circuit detection circuit and a wire output stop signal of the wire output stop signal output circuit, and a welding wire feed motor. In contrast, the output control circuit that outputs a control output signal having a certain inclination up to a steady condition is provided, and the output signal of the welding current detection circuit detects the absence of welding current at the time of arc start of welding start. During welding, the wire feed speed is set to the wire feed speed during steady welding, or the signal that becomes a slowdown speed that is slower than during steady welding. After outputting to the feed motor and the output signal of the welding current detection circuit detects the state with welding current, while the output signal of the wire short circuit detection circuit detects the wire short circuit state, the wire output stop signal output The output control circuit stops the welding wire feeding motor by the output signal of the circuit, and after detecting that the output signal of the wire short-circuit detection circuit is in the state of non-contact arc generation, a certain inclination until a steady condition is reached. A consumable electrode type welding power source characterized in that an output control circuit outputs a control signal having a value to a wire feeding motor.