JP2005288454A - Arc starting method, and welding equipment for consumable electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arc starting method capable of performing the uniform and stable arc start without generating any burn-up of a wire caused by deformation or buckling of the wire, and a welding equipment for a consumable electrode. <P>SOLUTION: In a case of the long-term short-circuit start having high probability of generating burning of a wire caused by deformation or buckling of the wire, the wire is fed in a reversely rotational direction before the wire is brought into contact with a work and the arc is started. The wire short-circuit is released by the reversely rotational direction in this method irrespective of the surface state, the tip shape, the diameter, the material, or the like of the wire, the arc is immediately started, and smooth and uniform arc starting performance can be obtained without any deformation or buckling of the wire. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to an arc start method for performing arc welding while continuously supplying a wire as a consumable electrode, and a consumable electrode welding apparatus.

    In the conventional consumable electrode welding apparatus, the arc start control method shown in the signal waveform of FIG. 11 has been adopted in order to make the arc state at the start of welding smooth (see, for example, Patent Document 1).

That is, while the absence of welding current is detected, the wire feed motor is turned on to feed a wire with a slow-down speed, the wire is brought into contact with the work piece, and an initial short-circuit current is detected (see FIG. 11). During the time t1), while detecting the short circuit state, the motor ON / OFF switching signal K is turned OFF to stop the wire feeding, and the arc state is detected (time t2 in FIG. 11), and then the motor ON / OFF switching signal. An arc start method was used in which K was turned on and the wire was fed at a steady welding speed and returned with a certain inclination.
JP-A-2-274378

    In general, in order to perform an instantaneous start with a good arc start, it is possible to selectively heat and melt the wire tip portion with an increased contact resistance between the wire tip and the work piece and generate an arc in this portion. is necessary.

    However, in the conventional arc start control method, when an insulating film such as slag is present at the tip of the wire, the insulating film is mechanically destroyed by the wire pressing force and an initial short-circuit current is applied. The problem is that a good arc start cannot be performed because the wire that has been fed before energization and stayed in the torch is pushed out to the contact part between the wire and the work piece with energization, and the contact resistance of that part decreases. Had.

    In particular, when the specific resistance of aluminum wire is low and it is difficult to melt, there are two types of states, an instantaneous start state and a long-term short-circuit start state. Instant start refers to contacting the wire with the workpiece. This is a start state in which an arc is generated immediately after detecting the short-circuit state and a short-circuit state is detected, and a short-circuit start state is a long-term short-circuit start state in which the wire is brought into contact with the workpiece to be welded. It is a start state where an energization is detected, a short circuit state is detected and an arc occurs after several tens of ms, but in a state such as the long time short circuit start, it is affected by differences in the wire surface state, tip shape, etc. Since the contact resistance between the contact part of the wire and the work piece decreases, the semi-molten state of the wire continues and it takes time to generate an arc, and the wire stops after detecting a short-circuit state. Leading to kindling wire to generate a buckled state of the pressing force is applied wire deformation, the wire had caused the problem, such as welded to the current chip.

    As a result, wire flares up due to wire deformation and buckling, and a uniform arc start state could not be obtained.

    An object of the present invention is to provide an arc start method and a consumable electrode welding apparatus capable of performing a uniform and stable arc start without generating wire burn-up due to wire deformation or buckling.

    In order to solve the above-mentioned problems, the present invention provides a high probability of generating wire burn-up due to wire deformation or buckling, for a long-time short-circuit start until the arc is generated after the wire contacts the work piece. Wire feed is transferred in reverse.

    With this method, regardless of the wire surface state, tip shape, wire diameter, wire material, etc., the wire is released from the short circuit by reverse transfer feeding, and an arc is generated immediately, without causing wire deformation or buckling. In addition, uniform arc start performance can be obtained.

    As described above, according to the present invention, when a short-circuit state is detected after a certain period of time after the wire comes into contact with the workpiece, the wire feed is reversely transferred and the short-circuit is released to There is no long-time short-circuit start state that causes wire burn-up from bending, and smooth and uniform arc start performance can be obtained particularly for aluminum wires and the like.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
(Embodiment 1)
6 and 7, 1 is a power input terminal for welding, 2 is a transformer for welding, 3 is a rectifying element, 4 is a welding output control terminal, 5 is a reactor for adjusting welding performance, 6 is a current detector, 7 is Power supply output terminal for welding, 8 is a contact tip for energization, 9 is a wire, 10 is a workpiece, 11 is a welding arc, 12 is a wire feed motor, 13 is a welding current detection circuit, 14 is a wire short circuit detection circuit, 15 Is an output control circuit, 16 is a microcomputer, 17 is a governor circuit, 18 is a motor drive voltage command circuit, 19 is a motor drive ON / OFF switching circuit, 20 is a motor polarity switching circuit, 21 is a transmission circuit, and 22 is a reception circuit. is there.

    A control method for the consumable electrode welding apparatus configured as described above will be described.

    The wire short circuit detection circuit 14 is connected between a pair of welding power supply output terminals, determines whether the welding output voltage is equal to or higher than a certain value, and determines whether the wire 9 is in contact short-circuit with the workpiece 10 based on the determination result. It is determined whether a welding arc is generated by contact, and a signal S is output.

    The welding current detection circuit 13 detects the presence or absence of a welding current and outputs a detection signal A.

    The output control circuit 15 receives the detection signal A and the signal S and outputs a signal M to the steady welding speed to the wire feed motor 12.

    In addition, the structure which outputs the signal M with a certain inclination to the steady welding speed with respect to the wire feed motor 12 like FIG. 4 may be sufficient.

    Further, the configuration in which the output control circuit 15 inputs the detection signal A and the signal S may be a configuration in which the output signal is input from the transmission circuit 21 via the reception circuit 22 as shown in FIG.

    Next, the output control circuit 15 comprises a microcomputer 16 and a governor circuit 17 for driving the motor. The governor circuit 17 includes a motor drive voltage command circuit 18, a motor ON / OFF switching circuit 19, and a motor polarity switching circuit 20. The detection signal A and the signal S are input to the microcomputer 16, the signal V is output to the motor drive voltage command circuit 18 according to the programming shown in FIG. N is output, and a signal K is output to the motor polarity switching circuit 20. Signals V, N and K from the microcomputer 16 to the governor circuit 17 are converted into a command signal M to the wire feed motor and output.

    Next, the operation of the above configuration will be described according to the programming shown in FIGS. 1 (A, B) and FIG.

    At the start of welding, the output control circuit 15 sends a slowdown speed output signal to the wire feed motor 12. When the wire 9 is fed at a slow-down speed and the wire 9 contacts and is short-circuited to the workpiece 10 (time t1 in FIG. 1), the welding current detection signal A outputs a state with a welding current. At the same time, the wire short circuit detection signal S outputs a wire short circuit state. The microcomputer 16 continues the slowdown speed so far in the case of an arc after a certain time (time t2 in FIG. 1) after receiving the signal A with welding current and the signal S of wire short circuit. In the case of a wire short-circuit state, the motor polarity switching signal K is reversely rotated, the command signal M to the wire feeding motor 12 is sent to the motor polarity switching circuit 20 of the governor circuit, and the wire is reversely transferred. Further, as shown in FIG. 5, it is possible to shift to stable steady welding by controlling the wire reverse transfer feed amount to 1 to 2/3 mm of the protruding amount.

    By continuing these control states, the wire 9 is released from the short-circuit state and an arc is generated (time t3 in FIG. 1). As a result, since the wire short circuit detection signal S is inverted to the arc state, the motor polarity switching signal K is rotated in the forward direction, and the motor polarity switching circuit 20 of the governor circuit 17 outputs to the wire feeding motor 12 the return to the slowdown speed. The signal M is output.

As described above, according to the present embodiment, when the wire 9 is in a short circuit state after receiving a signal A having a welding current and a signal S of a wire short circuit, the wire 9 is transferred in the reverse direction in the case of a wire short circuit state. It can be released from the short-circuit state and an arc can be generated.
(Embodiment 2)
In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

    The operation in the same configuration as that of the first embodiment will be described according to the programming shown in FIGS. 2 (A, B) and FIG.

    At the start of welding, the output control circuit 15 sends a slowdown speed output signal to the wire feed motor 12. When the wire 9 is short-contacted and short-circuited to the workpiece 10 (time t1 in FIG. 2), the welding current detection signal A outputs a state with a welding current. At the same time, the wire short circuit detection signal S outputs a wire short circuit state. Since the microcomputer 16 receives the signal A with the welding current and the signal S of the wire short circuit, the motor ON / OFF switching signal N is output as OFF, and is sent to the motor ON / OFF switching circuit 19 of the governor circuit and sent to the wire feeding motor. The command signal M to 12 stops the wire feeding. Further, after a certain time (time t2 in FIG. 2), in the case of an arc, the wire short circuit detection signal S is inverted to the arc state, so the motor ON / OFF switching signal N is output as ON, and the motor of the governor circuit An output signal M for returning to the slow-down speed is output to the feed wire feeding motor 12 to the ON / OFF switching circuit 19. When the wire is short-circuited, the motor ON / OFF switching signal N is output as ON and the motor polarity switching signal K is rotated in the reverse direction, and is sent to the motor polarity switching circuit 20 of the governor circuit 17 to send a command to the wire feeding motor 12. The signal M is a wire reverse transfer. Furthermore, it is possible to shift to stable steady welding by controlling the wire reverse transfer feed amount to 1 to 2/3 mm of the protruding amount. By continuing these control states, the wire 9 is released from the short-circuit state, and an arc is generated (time t3 in FIG. 2).

    As a result, since the wire short circuit detection signal S is inverted to the arc state, the motor polarity switching signal K is rotated in the forward direction, and the motor polarity switching circuit 20 of the governor circuit 17 outputs to the wire feeding motor 12 the return to the slowdown speed. The signal M is output.

    The present embodiment is different from the first embodiment in that the microcomputer 16 receives the signal A with the welding current and the signal S of the wire short circuit and outputs the motor ON / OFF switching signal N to turn off the motor ON / OFF. This is the point that the command signal M to the feed wire feed motor 12 is stopped at the switching circuit 19.

    As described above, according to the present embodiment, since the signal A with the welding current and the signal S of the wire short circuit are received, the state of the wire short circuit is detected, the wire feeding is stopped, and the wire short circuit is detected after a certain time. In the state, the welding wire is released from the short-circuit state by transferring the wire 9 in the reverse direction, and an arc can be generated.

This can generate an arc more quickly than in the first embodiment.
(Embodiment 3)
In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

    The operation in the same configuration as in the first embodiment will be described according to the programming shown in FIGS. 3 (A, B) and FIG.

    At the start of welding, the output control circuit 15 sends a slowdown speed output signal to the wire feed motor 12. When the wire 9 is short-contacted and short-circuited to the workpiece 10 (time t1 in FIG. 3), the welding current detection signal A outputs a state with a welding current. At the same time, the wire short circuit detection signal S outputs a wire short circuit state. Since the microcomputer 16 receives the signal A with welding current and the signal S of the wire short circuit, the motor polarity switching signal K outputs reverse rotation and is sent to the motor polarity switching circuit 20 of the governor circuit and sent to the wire feeding motor 12. The command signal M is transferred in reverse wire. Furthermore, it is possible to shift to stable steady welding by controlling the wire reverse transfer feed amount to 1 to 2/3 mm of the protruding amount. After a certain time (time t2 in FIG. 3), in the case of an arc, the wire short-circuit detection signal S is inverted to the arc state, so the motor polarity switching signal K is output as a normal rotation and sent to the motor polarity switching circuit. An output signal M for returning to the slow-down speed is output to the wire feed motor 12. In the case of a wire short-circuit state, the control state is continued, whereby the wire is released from the short-circuit state and an arc is generated (time t3 in FIG. 3).

    As a result, the wire short circuit detection signal S is inverted to the arc state, so that the motor polarity switching signal K is rotated in the forward direction, and the motor polarity switching circuit 20 of the governor circuit 17 returns to the wire feed motor 12 to the slowdown speed. Is output.

    The present embodiment is different from the first embodiment in that the microcomputer 16 receives the signal A with welding current and the signal S of the wire short circuit, and the motor polarity switching signal K outputs reverse rotation, and the motor polarity switching circuit 20 The command signal M to the feed wire feed motor 12 is a reverse transfer feed.

    As described above, according to the present embodiment, since the signal A with the welding current and the signal S of the wire short circuit are received, the state of the wire short circuit is detected and the wire is transferred in the reverse direction. In the case of the state, by continuing the control state, the wire 9 is released from the short-circuit state, and an arc can be generated.

    This can generate an arc more than in the second embodiment.

    According to the present invention, the arc start state in which a pressing force is applied until the wire stops due to the influence of the difference in the wire surface state and the tip shape, etc., causing a buckling accident from the wire deformation and causing the wire burn-up, etc. It is possible to provide a uniform and stable arc start state regardless of the wire surface state, tip shape, wire diameter, wire material, etc., and arc welding while continuously feeding the welding wire as a consumable electrode This is useful for a consumable electrode welding apparatus.

FIG. 2 is a signal waveform diagram according to the first embodiment of the present invention, where (A) is a signal waveform at the time of instantaneous start, and (B) is a signal waveform diagram at the time of starting a short circuit for a long time. FIG. 7 is a signal waveform diagram according to the second embodiment of the present invention, where (A) is a signal waveform at the time of an instantaneous start, and (B) is a signal waveform diagram at the time of a short-circuit start. FIG. 4 is a signal waveform diagram according to the third embodiment of the present invention, where (A) is a signal waveform at the time of instantaneous start, and (B) is a signal waveform diagram at the time of starting a short circuit for a long time Signal waveform diagram returning to slow-down speed with a certain slope after detecting the arc state in Embodiment 1 of the present invention Signal waveform diagram in which wire reverse transfer feed amount in Embodiment 1 of the present invention is pulled back from 1 to 2/3 mm of protruding amount The block diagram of the welding apparatus in embodiment of this invention The block diagram which provided the transmission / reception circuit in the welding apparatus in embodiment of this invention Microcomputer programming flowchart according to the first embodiment of the present invention Microcomputer programming flowchart according to the second embodiment of the present invention Microcomputer programming flowchart according to the third embodiment of the present invention Signal waveform diagram in the arc start method of the conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply input terminal for welding 2 Transformer for welding 3 Rectifier 4 Welding output control terminal 5 Reactor for welding performance adjustment 6 Current detector 7 Power supply output terminal for welding 8 Contact tip for electricity supply 9 Wire 10 Workpiece 11 Welding arc 12 Wire feed motor 13 Welding current detection circuit 14 Wire short circuit detection circuit 15 Output control circuit 16 Microcomputer 17 Governor circuit 18 Motor drive voltage command circuit 19 Motor drive ON / OFF switch circuit 20 Motor polarity switch circuit 21 Transmit circuit 22 Receive circuit

Claims (7)

When welding is started, the wire is fed toward the work piece at a slow-down speed that is equal to or lower than the wire feed speed during steady welding to contact the work piece. Detects whether it is in an arc state or a short circuit state after a certain period of time from the detection of the short-circuit current. In the arc state, the wire feed at the slowdown speed is continued, and in the short-circuit state, the wire is transferred in the reverse direction to short-circuit. An arc start method in which a wire is transferred forward and returned to a slowdown speed after being released and detecting an arc state. The wire is brought into contact with the work piece, the wire feeding is stopped when the initial short-circuit current is detected, the wire is returned to the slow-down speed in the arc state after a certain time, and the wire is fed in the short-circuit state. The arc start method according to claim 1, wherein the wire is transferred forward and returned to the slow-down speed after the arc is detected by reversely feeding and releasing the short circuit. The wire is brought into contact with the work piece, the wire feed is transferred backward after detection of the initial short circuit current, and the wire is transferred forward in the arc state after a certain period of time to return to the slow-down speed wire feed. 2. An arc start method according to claim 1, wherein, in the case of a short circuit state, the wire is reversely transferred continuously to release the short circuit and the arc state is detected, and then the wire is transferred forward and returned to the slowdown speed. . The arc start method according to any one of claims 1 to 3, wherein in the case of a short-circuit state, the return speed to the slow-down speed after detecting the arc state has a constant slope. The arc start method according to any one of claims 1 to 3, wherein in the case of a short circuit, the reverse feed amount of the wire feed is controlled to protrude from 1 to 2/3 mm. A welding current detection circuit for detecting the presence or absence of a welding current, a wire short-circuit detection circuit for determining whether the wire is in contact short-circuit or non-contact with the workpiece, and outputting a signal, and the welding current detection circuit; Consumable electrode welding apparatus provided with an output control circuit that outputs an output signal to the wire short circuit detection circuit as an input signal and outputs a signal for forward or reverse transfer of the wire to the wire feeding motor or to stop feeding. . A welding current detection circuit for detecting the presence or absence of a welding current, a wire short-circuit detection circuit for determining whether the wire is in contact short-circuit or non-contact with the workpiece, and outputting a signal, and the welding current detection circuit; A transmission circuit that transmits an output signal to the wire short-circuit detection circuit, a reception circuit that receives a signal from the transmission circuit, and forward and reverse transfer of the wire to the wire feeding motor in response to the output signal of the reception circuit A welding apparatus for consumable electrodes provided with an output control circuit for outputting a signal for stopping feeding or feeding.