JPH04111972A - Consumable electrode arc welding method and welding equipment - Google Patents

Abstract

PURPOSE:To make proper transient electrode melting by sending a pulse current after stopping the feed voltage to an electrode feed motor according to a consumable electrode arc welding completion signal. CONSTITUTION:In consumable electrode arc welding where a welding current is applied to a consumable electrode fed by supplying the feed voltage to the consumable electrode feed motor to perform welding, the electrode feed voltage of the consumable electrode feed motor is stopped according to the welding completion signal of a welding starting and completion switch. Afterward, it is detected that the armature voltage of the consumable electrode feed motor decreases to less than a specified value and the welding current is converted into the pulse current which is applied to complete it. Consequently, transient electrode melting due to inertia of the electrode feed motor and an electrode feed mechanism can be made proper.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a consumable electrode (hereinafter referred to as a wire) that reduces the size of a molten ball that adheres to the tip of a consumable electrode (hereinafter referred to as a wire) at the end of welding to improve the next arc start. The present invention relates to an electrode arc welding method and a welding device.

[Prior Art] The prior art will be explained with reference to FIG. 9. Generally, in the consumable electrode arc welding method, at the end of welding, a welding start/end switch is pressed to generate a welding end signal at time tf, as shown in FIG. feed voltage WC to the feed motor)
Even if the motor is stopped, the inertia of the motor and feeding mechanism causes the wire to be fed by a small amount transiently, and the wire feeding speed gradually decreases as shown in Figure (B). Vf becomes small and stops from time tl to t3. The transient wire feeding amount from when the feeding voltage Wc to the wire feeding motor is stopped until the wire feeding speed reaches zero and the wire feeding completely stops is the amount of wire fed from the wire feeding motor and Even if the feeding mechanism is the same, it changes depending on many factors such as the wire feeding speed during welding, the material of the wire, the diameter of the wire, the curvature of the wire guide, and the state of friction. Due to this transient wire feeding amount, the same figure (E
) As shown by the dotted line, the wire tip 1a plunges into the molten pool 2a of the workpiece 2, causing a welding defect, or the wire tip protruding into the molten pool and welding, so-called stick, which may cause the next Arc start may become impossible. Therefore, conventionally, as shown in FIG. 5(A), from the time tf when the feed voltage Wc to the wire feeding motor is stopped, a timer or the like is used to delay (
The output voltage (hereinafter referred to as welding output voltage) Et of the welding power source is stopped to melt this transient wire feed amount by giving T1 to T3 (hereinafter referred to as antistick time). There is.

In addition, when using a welding power source with constant voltage characteristics such as carbon dioxide arc welding or MAG welding, if you allow a long anti-stick time, the wire will melt even after the wire has stopped, increasing the arc length. The arc voltage increases transiently due to so-called burn-out of the arc, approaches the no-load voltage of the welding power source, and the arc automatically extinguishes. Therefore, when using a welding power source with constant voltage characteristics, there may be a problem of so-called burnback, where the electrode tip tip 4a and the shortened wire tip 1a are welded together due to burnout of the arc. When the arc burns out, a molten ball 1b is generated at the tip of the wire, and if this molten ball becomes large, the next arc cannot be started properly. The diameter of the molten ball generated at the tip of the wire is determined by the appropriate value Hb of the distance between the wire tip 1a and the molten pool surface 2b (hereinafter referred to as the burn-out height) when the wire material is steel-based. [mm], the wire diameter is 1°2[w
It has been experimentally confirmed that 1.2 to 1.8 [+nm] is good for . Therefore, in the consumable electrode arc welding method, in order to prevent the molten ball from becoming large, during or after the anti-stick time by the timer has elapsed,
Various methods have been proposed, such as supplying a pulse current between the electrode tip 4 and the workpiece 2 and then stopping the welding output.

Furthermore, in the consumable electrode pulse arc welding method, after the output time tf of the welding end signal, as shown in FIG. In the method of terminating, the same figure (E)
As shown in FIG. 2, the height Hb of the burnt-out scum becomes large, and the molten ball 1b at the tip of the wire becomes large. Therefore, the same figure (F)
As shown at time tf in FIG. ), it has been proposed to set the height after baking to an appropriate value Hb.

[Problems to be solved by the invention] In the conventional consumable electrode arc welding method and welding device,
At the end of welding, the wire is melted by selecting a delay time corresponding to the transient amount of wire feed from when the power supply to the wire feed motor is stopped until the wire feed completely stops. The output voltage of the welding power source is stopped after the As mentioned above, even if the wire feeding motor and feeding mechanism are the same, this transient wire feeding amount greatly affects the magnitude of the wire feeding speed during welding. It varies depending on many factors such as the diameter of the wire, how the wire guide is bent, and friction conditions. therefore,
In the conventional welding method and welding equipment, this transient wire feed amount is melted by delaying the stop of the output voltage of the welding power source using a timer. It is very difficult to set the timer delay time so as to match the amount of wire melting. If you simply want to prevent the wire from sticking by using a welding power source with constant voltage characteristics, you can simply set the anti-stick time to be long and automatically extinguish the arc as it burns out. No problem. However, in a power supply with constant voltage characteristics, controlling only the anti-stick time is insufficient in order to make the grain of the wire appropriate (smaller). The reason for this is that the voltage value supplied during anti-meshing greatly influences the particle size. Therefore, in a power supply with constant voltage characteristics, a method has been proposed in which a pulse current is superimposed at the time of anti-mechanism in order to make the particle size even smaller than usual and to reduce the variation.However, when a pulse current is superimposed, However, some problems arise with the pulsed arc welding method. In particular, when welding using a small current in the MIG arc welding method for aluminum, the molten ball tends to become large, so the timer cannot be set to an appropriate value.

Also, when welding aluminum, steel, and other materials using a constant-current controlled welding current, increasing the antistick time will increase the burnout height of the arc and increase the arc voltage. Also, since constant current is controlled, the no-load voltage is high, so the arc does not disappear automatically and the tip of the electrode tip and the tip of the wire weld together, which is what is called burnback. Therefore, unlike welding methods that use constant voltage characteristics, welding methods that use a welding current that is controlled by a constant current cannot set a long antique time, and the selection of the timer setting time is more difficult. It becomes even more difficult.

Furthermore, in the consumable electrode pulse arc welding method and welding device, both the pulse current value and the base current value are controlled to a constant value, that is, constant current control, and the arc length is kept constant by increasing or decreasing the ratio between the pulse current application period and the base current application period. When controlling the wire to a value or magnitude, if the wire feeding is almost stopped during the base current energization period, the arc length becomes large, and if the arc voltage becomes large, feedback control is performed to lower the arc voltage. Therefore, as shown in FIG. 9(D), the base current continues and the next pulse current does not flow. Therefore, even if an attempt is made to stop the output voltage of the welding power source while waiting for the next pulse current, it may not be possible. Therefore, large molten spheres are generated at the tip of the wire, and even burnback occurs.

To summarize the problems with this conventional consumable electrode pulse arc welding method and welding device with reference to Fig. 1-0, as shown in Fig. 1-0 (A), the supply voltage to the wire feed motor is Assume that when We is stopped at time tf, the wire feeding speed Vf gradually decreases and completely stops at time tg, as shown in FIG. If the output current of the welding power source (hereinafter referred to as welding output current) is stopped immediately after pulse current application at time t4, large molten balls will not be generated at the tip of the wire, but it will completely stop from time t4 at time tg. Depending on the amount of wire fed transiently during this period, the wire tip may stick to the molten pool, or even when it does not reach the stick, the wire tip may come into contact with the molten pool, resulting in welding at the end of welding. Defects may occur in metals. Conversely, as shown in the same figure (C), even if an attempt is made to stop the welding output current immediately after the pulse current is energized at time t6, which is after time t4, the wire feeding becomes less than the predetermined value. Therefore, the arc length becomes large during the base current energization period, and this arc voltage is feedback-controlled to try to shorten the arc length, so the next pulse current is not energized and the base current continues. The flow caused a large molten ball to form at the tip of the wire, and finally,
Even burnback will occur. That is, the time t when the feed voltage Wc to the wire feed motor is stopped.
The optimum value for the time from f to stopping the output current of the welding power source immediately after applying the pulse current is t5, and it is not possible to always select this optimum value t5 by a timer for the transient wire feed amount. This is extremely difficult in practice.

[Means for Solving the Problems] The present invention is constituted by the following means in order to solve the above problems.

The invention of claim 1 provides welding by supplying a welding current with substantially constant voltage characteristics or constant current characteristics and feeding a consumable electrode at a preset substantially constant speed, or welding with substantially constant current characteristics. In a consumable electrode arc welding method in which a welding current is supplied from a power source and the consumable electrode is fed at a speed such that the arc voltage becomes approximately constant, the supply voltage of the wire feed motor is changed by the welding end signal Ts. This is a welding method in which the welding current is stopped, the armature voltage of the wire feed motor is detected to be below a predetermined value, the welding current is switched to a pulse current, and the energization is then terminated. .

The invention of claim 2 is the same welding method as claim 1, in which the feeding voltage Wc of the wire feeding motor is stopped by the welding end signal Ts, and the pulse current and the base current are repeatedly energized. This is a welding method in which it is detected that the armature voltage of the wire feed motor has become below a predetermined value, and the final pulse current is applied, and then the pulse current is stopped.

The invention according to claim 3 provides a consumable electrode arc welding method in which a pulse current and a base current are repeatedly supplied from a welding power source, and a consumable electrode is fed at a preset substantially constant speed for welding. The feed voltage Wc of the wire feed motor is stopped by the signal Ts, and then, after detecting that the armature voltage of the wire feed motor has become below a predetermined value and passing a pulse current, the output of the welding power source is stopped. This is a welding method that stops the process.

The invention of claim 4 provides a welding apparatus for implementing the welding method of the invention of claim 1, as shown in the block diagram of FIG. An armature voltage comparison circuit CM1 outputs a motor stop signal Cml when the armature detection voltage Wd of the wire feed motor becomes less than a predetermined value, a pulse current setting circuit IP outputs a pulse current signal 1p, and a motor stop signal Cml. It is equipped with a welding output/pulse switching circuit SW2 that switches a welding output control signal (welding voltage control signal Cm2 or welding current control signal Cm3) to a pulse current signal Ip and outputs it to the welding output control circuit PS. This is a welding device that stops the feed voltage We of the feed motor, switches from a welding current with constant voltage characteristics or constant current characteristics to a pulse current, and ends the application of the pulse current.

The invention of claim 5 provides a welding apparatus for implementing the welding method of the invention of claim 2, as shown in the block diagram of FIG.
a pulse current setting circuit IP that outputs a pulse current setting circuit IP, a base current setting circuit IB that outputs a base current signal Ib, and a pulse current setting circuit IP that outputs a pulse current signal 1p and a base current signal Ib according to a welding end signal Ts.
A pulse current signal switching circuit SWI outputs a pulse base signal SW1 by switching between the two signals, and a welding output control signal (welding voltage control signal) Cm2 is switched from a welding output control signal (welding voltage control signal) Cm2 to a pulse base signal Sw1 and input to the welding output control circuit PS according to a welding end signal Ts. a welding output/pulse switching circuit 5W2-2, and an armature that stops the feed voltage Wc in response to the welding end signal Ts and outputs a motor stop signal Cml when the armature detection voltage Wd of the wire feed motor becomes less than a predetermined value. It is equipped with a voltage comparison circuit CM1 and a pulse stop signal generation circuit TR that receives a motor stop signal Cml as input and outputs a pulse current stop signal Tr, and stops the supply voltage We in response to a welding end signal Ts, Switch the current characteristics from welding current to pulsed current, and then input the motor stop signal Cml to the pulsed current signal switching circuit SWI to create the final pulsed current signal 1.
This is a consumable electrode arc welding device in which a final pulse current is applied by applying current p, and then the final pulse current is stopped by a pulse current stop signal Tr.

The invention according to claim 6 provides a welding apparatus for carrying out the welding method according to the invention according to claim 3, in which a pulse current signal Ip set by a pulse current setting circuit IP is provided, as shown in the block diagram of FIG. and a base current signal 1b set in the base current setting circuit IB, and a welding output control circuit PS that outputs a welding current consisting of the pulse current and the base current by inputting the pulse base signal SW1 consisting of the base current signal 1b set in the base current setting circuit IB, and In a welding device equipped with a wire feed control circuit WC that supplies a feed voltage We for feeding a consumable electrode to a wire feed motor, the wire feed motor an armature voltage comparison circuit CMI that outputs a motor stop signal Cm 1 when the armature detection voltage Wd of the armature becomes equal to or less than a predetermined value; and a pulse stop signal generation circuit TR that receives the motor stop signal Cm 1 as an input and outputs a pulse current stop signal Tr. After stopping the feed voltage Wc in response to the welding end signal Ts, a motor stop signal Cml is provided.
This is a welding device in which a final pulse current IPn is applied, and then the final pulse current IPn is stopped by a pulse current stop signal Tr.

[Embodiment 1] FIG. 1 is a block diagram of an embodiment of a welding apparatus according to claim 6 for implementing the pulse arc welding method according to claim 3. The welding device shown in the figure applies a pulse current with a constant peak value and a base current with a constant current value so that one droplet transfers per pulse, detects the arc voltage, and then changes the pulse current and base current. By controlling the energization period, the circuit configuration can minimize transient arc length fluctuations and set the arc length short, and detect the armature voltage of the wire feed motor at the end of welding. This welding device combines a circuit configuration that stops the pulse current at the end of the pulse current energization period immediately after the pulse current becomes equal to or less than a predetermined value.

(Explanation of the configuration) In the same figure, a pulse current and a base current are inputted from a commercial power source AC from a welding output control circuit PS to a consumable electrode 1.
The arc 3 is supplied between the electrode tip 4 and the workpiece 2.
to occur. The consumable electrode 1 is supplied by a wire feed roller WR rotated by a wire feed motor WM. The average current setting circuit IM outputs an average current setting signal Im for setting an average value Ia of welding current determined by the wire feeding speed of the wire feeding motor WM. The wire feed control circuit WC receives the signal Im and outputs a feed voltage Wc to the wire feed motor WM. Supply voltage stop circuit N0
T2 is a welding start/end switch TS for starting welding.
When the welding start signal Ts is output by pressing , and the holding signal sh during welding is being output from the holding circuit SH in solution, supply the feeding voltage Wc to the wire feeding motor WM, and then Then, when the welding start/end switch is pressed again and the welding hold signal sh stops, the supply voltage is stopped. The armature voltage comparison circuit CMI compares the armature detection voltage Wd with the armature reference voltage We set by the armature reference voltage circuit WE, and outputs a motor stop signal Cml when the difference signal becomes less than a predetermined value. Output. The pulse stop signal generation circuit TR outputs a pulse current stop signal Tr when the armature pulse signal Mml of the mono-multi oscillation circuit MM is input. The flip-flop circuit FFI outputs the output terminal Q when the welding end signal Ts is input to the set terminal S.
When the pulse current stop signal Tr is input to the reset terminal R, the energization signal Ffl of the output terminal Q is stopped.

The welding voltage comparison circuit CM2 compares the welding voltage detection signal Vd of the welding voltage detection circuit VD and the welding voltage setting signal Vs of the welding voltage setting circuit VS, and generates a welding output control signal (welding voltage control signal) CM2 of the difference. Output. The pulse frequency control circuit VF outputs a pulse frequency conversion signal Vf corresponding to the pulse period in response to the welding voltage control signal Cm2. The OR circuit ORI receives the pulse frequency signal M m 2 or the armature pulse signal M m of the monomulti oscillation circuit MM2.
1 is input, a pulse current switching signal Orl is output. The pulse current signal switching circuit SW1 is
Every time the pulse current switching signal Orl is input, the base current signal Ib set by the base current setting circuit IB,
Pulse current signal r set by pulse current setting circuit IP
p and outputs the pulse base signal Swl. The welding current comparison circuit CM3 compares the pulse current signal Ip and the welding current detection signal Id corresponding to the instantaneous value of the welding current detected by the welding current detection circuit ID during the pulsed current application period, and controls the welding output based on the difference. Signal (welding current control signal) C
Welding output control circuit PS through m3 drive circuit DV
Furthermore, during the base current energization period, the base current signal 1b and the welding current detection signal Id are compared to control the base current value to be constant in the same order as above. . Welding current signal stop circuit N0T1 is
When the energization signal Ffl is input, the drive circuit DV
The welding output control signal Dv is supplied to the welding output control circuit ps.

(Description of operations from the start of welding to during welding) The operations of the welding apparatus of the present invention from the start of welding to during welding will be described with reference to FIGS. 1 and 2.

As shown in FIG. 2(A), at time ta, the welding start/end switch TS is pressed to output a welding start signal Ts to the in-solution holding circuit SH and the flip-flop circuit FFI. Due to the holding signal sh during welding from the holding circuit SH in solution, the supply voltage stop circuit N0T2 becomes conductive and the supply voltage Wc
is supplied to the wire power feeder WM. Wire feeding motor W
M feeds the wire at a wire slowdown speed as shown in FIG. 2(B). When the wire slowdown speed is exceeded, the negative voltage of the armature detection voltage Wcl becomes larger than the positive voltage of the armature reference voltage We, so the armature voltage comparison circuit CMI is as shown in FIG. 2(C). Therefore, the motor stop signal Cml is not output. Therefore, both the mono-multi oscillation circuit MM1 and the pulse stop signal generation circuit TR do not output signals.

On the other hand, the welding start signal Ts is input to the set terminal S of the flip-flop circuit FFI, as shown in FIG. Make N0T1 conductive. At the start of welding, a pulse current signal switching circuit SWI, which will be described later, is set to connect the pulse current setting circuit IP and the welding current comparison circuit CM3. Therefore, the pulse current signal Ip is input to the drive circuit DV through the comparison circuit CM3, and the welding output control signal D
v is the welding output control circuit P through the circuit N0T1 mentioned above.
A pulse current IPI is input to S, and as shown in FIG. 2(G), a pulse current IPI is applied. This switching circuit SWI conducts the pulse current signal ip and then conducts the base current signal Ib. When an arc occurs here, the welding voltage detection signal Vd and welding voltage setting signal Vs are compared, the welding voltage control signal Cm2 is input to the pulse frequency control circuit VF, and the pulse frequency conversion signal Vf is output.

This signal Vf is input to the monomulti oscillation circuit MM2,
The output pulse frequency signal M m 2 is OR circuit OR
The above-mentioned pulse current signal 1p is applied through I, and the pulse current IP2 shown in FIG. 2(G) is applied. below,
Arc welding is performed by repeating the same operation and applying the pulse current and base current.

(Explanation of operation at the end of welding) At time tf in FIG. 2(A), when the welding start/end switch Ts is pressed again to output the welding end signal Ts,
The welding holding signal sh of the welding raw holding circuit SH stops, the feed voltage stop circuit N0T2 becomes non-conductive, the feed voltage Wc to the wire feed motor WM stops, and the feed motor WM has a back electromotive force. As a result, the armature detection voltage Wd gradually decreases as shown in FIG. 2(B). During the period in which the armature detection voltage Wd is gradually decreasing, the output terminal Q of the flip-flop circuit FFI has not yet stopped the energization signal Ffl as described later, so the welding current signal stop circuit N0TI is still in the conducting state. Therefore, the welding output control circuit PS continues to output the welding current I.

When the armature detection voltage Wd becomes equal to or less than a predetermined value at time tg shown in FIG. 2(B), the motor stop signal C is output from the armature voltage comparison circuit CMI as shown in FIG. 2(C).
ml is output, and as shown in FIG. 4(D), the mono-multi oscillation circuit MM1 outputs an armature pulse signal M m 1, which is input to the pulse current signal switching circuit SWI through the OR circuit ORI. Therefore, this switching circuit SWI
The pulse current signal 1p is input to the welding output control circuit PS through the welding current comparison circuit CM3, the drive circuit DV, and the welding current signal stop circuit N0T1, and this control circuit PS inputs the pulse current IPn shown in FIG. energize,
The molten ball 1b at the tip of the wire is separated by applying a pulse current. On the other hand, as shown in (D) and (E) of the same figure, the armature pulse signal M of the mono-multi oscillation circuit MMI
When the pulse stop signal generation circuit TR generates the pulse current stop signal Tr and inputs it to the reset terminal R of the flip-flop circuit FFI at the timing of the falling edge of m1, the output terminal Q of this circuit FF1 becomes as shown in the figure ( As shown in F), the energization signal Ffl is stopped. Welding current signal stop circuit N
At 0T1, by stopping this energization signal Ffl, the welding output control signal Dv of the drive circuit DV is stopped, so as shown in FIG. It doesn't flow either. Therefore, as mentioned above, with the final pulse current IPn,
Since the molten ball 1b at the tip of the wire has been sufficiently separated, there is no remaining molten ball at the tip of the wire, and the final pulse current is applied by detecting that the wire power transmission has almost stopped. Because of this, residual wire feed after the welding current stops will not cause stick. On the other hand, if this last pulse current is applied after wire feeding is stopped, the burned-out height Hb will not become too large and burnback will not occur. Figure 2 mentioned above (
In the embodiment G), the last pulse current IPn is applied without time delay by the armature pulse signal M m 1 outputted by the monomulti oscillation circuit MMI with the motor stop signal Cml as input. As shown in Figures (H) to (J), a monomulti oscillation circuit M is provided with a time delay T5 from the output signal of this motor stop signal Cml.
By outputting the armature pulse signal M m 1 from MI, the last pulse current IPn may be delayed and energized.

[Embodiment 2] FIG. 3 is a block diagram of an embodiment of a welding apparatus according to claim 5, in which the welding method according to claim 2 is carried out using a welding current with constant voltage characteristics. The welding device shown in the figure outputs a welding current with approximately constant voltage characteristics, feeds the consumable electrode at a preset speed for welding, and stops the feeding voltage of the wire feed motor upon receiving a welding end signal. At the same time, the welding device switches the welding current to a pulsed current with constant voltage characteristics to supply the pulsed current, and then stops the final pulsed current by a pulsed current stop signal.

(Description of Configuration) In FIG. 3, the configuration that differs from that in FIG. 1 is as follows. First of all, a second welding output/pulse switching circuit 5W2-2 and a pulse frequency control circuit VF are used to input a welding output control signal (welding voltage control signal) Cm2 to the drive circuit DV according to the in-solution retention signal Sh. A first welding output/pulse switching circuit 5W2-1 is added.

Second, the above switching circuit 5W2 is activated by the welding holding signal sh.
A second welding output/pulse switching circuit SW2 is added which switches between the welding voltage control signal Cm2 and the welding current control signal Cm3 outputted from -1 and outputs them to the drive circuit DV. The other circuits are the same as those in FIG. 1, so their explanation will be omitted.

(Operation explanation) When the welding start/end switch TS is pressed, the solution hold signal s
h is input to the welding output/pulse switching circuits 5W2-1 and 5W2-2 mentioned above, and the welding output control signal (welding voltage control signal) Cm2 is inputted to the welding output control circuit PS through the drive circuit DV, and the constant voltage A characteristic welding current is output and welding is performed.

Next, when the welding start/end switch TS is pressed again, the solution holding signal sh is stopped, the welding output/pulse switching circuits S, W2-1, and 5W2-2 are switched, and the welding voltage control signal Cm2 is changed to the pulse frequency. On the other hand, the welding current control signal Cm3 is input to the welding output control circuit PS through the drive circuit DV, and as shown in FIG. 4(B), as in the case of FIG. The base current is repeatedly energized. By repeatedly applying the pulse current and the base current, it is possible to synchronize the droplet transfer from the tip of the wire with the application of the pulse current. Subsequently, as shown in FIG. 4(A), when the armature detection voltage Wd becomes less than a predetermined value, the same operation as in FIG. 1 occurs. Also in the case of this Fig. 3, welding end signal Ts
As a result, the pulse current and the base current are repeatedly applied, so the transfer of the droplet from the wire tip and the application of the pulse current can be synchronized, so that the final pulse current I
As the molten ball 1b at the tip of the wire is sufficiently separated by the energization of Pn, there is no remaining molten ball at the tip of the wire, and as in the case of Fig. 1, there is no possibility of stick or burnback. Not at all.

[Embodiment 3] FIG. 5 is a block diagram of an embodiment of a welding apparatus according to claim 4, which implements the welding method according to claim 1 with constant voltage characteristics. The welding device shown in the figure outputs a welding current with approximately constant voltage characteristics, feeds the consumable electrode at a preset speed, and stops the feed voltage of the wire feed motor in response to a welding end signal. This is a welding device that switches to the voltage and current for crater treatment, then applies two pulse currents to complete the welding process.

(Description of Configuration) In FIG. 5, the configuration different from that in FIG. 1 is as follows. First, a crater processing voltage setting circuit VT outputs a crater processing voltage signal Vt, and a welding voltage setting signal Vs is set as a crater processing voltage signal V by a welding end signal Ts.
t, a crater processing current setting circuit IT that outputs the crater processing current signal It, and a crater processing current switching circuit SW4 that switches the welding current setting signal 1m to the crater processing current signal It in accordance with the welding end signal Ts. has been added.

Second, the welding output/pulse switching circuit S switches the welding voltage control signal Cm2 to the welding current control signal Cm3 using the armature pulse signal Mm1 and outputs it to the drive circuit DV.
W2 has been added. Thirdly, the crater treatment holding signal Th is output in response to the welding end signal Ts, or the crater treatment holding signal Th is continuously outputted even after the welding end signal Ts is output, and the crater treatment holding signal Th is output again during the crater treatment current energization period (3
(time) a crater processing holding circuit TH that stops the crater processing holding signal Th after pressing the welding start/end switch TS or after the time of a timer in the crater processing holding circuit TH has expired;
The in-solution retention signal sh and the crater treatment retention signal Th are input, and the OR signal Or2 is sent to the supply voltage stop circuit N0T2.
An OR circuit OR2 is added to output the output signal. Fourth, the pulse frequency control circuit VF, monomulti oscillation circuit MM2, OR circuit ORI, and base current setting circuit I in FIG.
B is omitted. The other circuits are the same as those in FIG. 1, so their explanation will be omitted.

(Operation description) When the welding start/end switch TS is pressed, the welding output control signal (welding voltage control signal) Cm2 is input to the welding output control circuit PS via the welding output/pulse switching circuit SW2 and the drive circuit DV, and the constant voltage characteristic Welding current is output and welding is performed.

Next, when the welding start/end switch TS is pressed again, the solution holding signal sh is stopped, and the crater processing type pressure switching circuit S
W3 is switched, and the crater processing voltage signal Vt is input to the welding output control circuit PS through the welding output/pulse switching circuit SW2 and the drive circuit DV, and the crater processing voltage is output. In addition, by stopping the in-solution retention signal sh,
Since the crater processing hold signal Th is output and supplied to the supply voltage stop circuit N0T2 through the OR circuit OR2, this circuit N0T2 continues to conduct. At the same time, the crater processing current switching circuit SW4 is switched due to the stop of the in-solution retention signal sh, and the crater processing current signal It is input to the wire feeding control circuit WC, so that the wire feeding speed becomes the crater processing current. Crater processing is performed.

After removing the crater, turn the welding start/end switch TS again (3
Crater processing hold signal T by pressing or timer
h is stopped, the feeding voltage We to the wire feeding motor WM is stopped, and as shown in FIG. 6(A), when the armature detection voltage Wc+ gradually decreases to a predetermined value or less, the The welding output/pulse switching circuit SW2 is switched by the armature pulse signal M m 1 outputted in the same manner as in the case, and the welding current output is controlled using the signal of the difference between the pulse current signal Ip and the welding current detection signal Id through the drive circuit DV. A pulse current IPn is applied to the circuit PS as shown in FIG. 6(B). Subsequently, as in the case of FIG. 1, the pulse current stop signal Tr is input to the reset terminal R of the flip-flop circuit FFI, and the energization signal Ff at its output terminal Q is stopped, thereby stopping the pulse current. By applying this pulsed current, the molten ball 1b at the tip of the wire separates, so that the molten ball 1b at the tip of the wire does not become large particles and does not stick or burn back. In addition, in this example,
Since the pulse current is not applied during crater treatment,
Since the molten ball at the tip of the wire is attempted to be separated with only one pulse, the size of the molten ball at the tip of the wire may vary more than in Examples 1 and 2 described above. susceptible to fluctuations. In this embodiment, when changing to a pulse current setting circuit IP in which the pulse current signal rp disappears after being energized for a predetermined time,
The pulse stop signal generating circuit TR of this embodiment is not necessary.

[Embodiment 4] FIG. 7 is a block diagram of an embodiment according to claim 5, in which the welding method according to claim 2 is carried out using a welding current with constant current characteristics. When performing MIG welding on materials such as copper, stainless steel, and stainless steel with a relatively large current, a welding current with constant current characteristics is supplied and the consumable electrode is welded at a preset approximately constant value that shortens the arc length. When welding by feeding at a high speed, when the balance between the wire feeding speed and the wire melting speed during welding is lost and the arc length becomes shorter, the amount of melting increases and balances, a phenomenon called arc It has inherent self-regulatory properties. FIG. 7 shows a block diagram in the case of welding using this characteristic.

(Description of Configuration and Operation) In FIG. 7, the configuration different from that in FIG. 1 is as follows. First, in FIG. 7, a welding current setting circuit IF is provided which outputs a welding current setting signal If. Second, between the pulse current signal switching circuit SWI and the welding current comparison circuit CM3, the welding current setting signal If is changed to the pulse base signal Swl by the termination of the current holding signal sh.
A welding output/pulse switching circuit SW2 is provided. Thirdly, instead of the average welding current setting circuit IM in FIG. 1, a wire feeding speed setting circuit WF sets a wire feeding speed signal Vf obtained from the arc-specific self-control characteristics.
Usually, this setting circuit WF is integrated with the welding current setting circuit IF. In this embodiment, the connection shown by the dashed-dotted line for inputting the welding voltage control signal Cm2 to the wire feed control circuit WC is not made. Moreover, the dotted line between the wire feed speed setting circuit WF and the wire feed speed control circuit WC is connected. When the welding start/end switch TS is pressed, the welding output/pulse changeover switch SW2 is switched by the welding hold signal sh, and the welding current setting signal If is input to the welding current comparison circuit CM3, so the welding current setting signal If and welding Current detection signal 1d
Welding output control signal (welding current control signal) of the difference between Cm3
is input to the welding output control circuit PS through the drive circuit DV, and a welding current with constant current characteristics is output to perform welding.

Next, when the welding start/end switch TS is pressed again, the welding holding signal sh is stopped, the welding output/pulse switching circuit SW2 is reset, and the pulse base signal Swl is input to the welding current comparison circuit CM3. The subsequent operations are the same as in FIG.

(Modified example) In FIG. 7, the wire feed speed signal Wf set by the wire feed speed setting circuit WF of the wire feed motor is inputted to the wire feed control circuit WC, and the output feed voltage W
An example in which the consumable electrode is fed at a substantially constant speed has been described with reference to FIG. 7, but in the example shown in FIG. By this, a welding output control signal (welding voltage control signal) Cm2, which is the difference between the welding voltage setting signal Vs and the welding voltage detection signal Vd, is input to the wire feeding control circuit WC instead of the wire feeding speed signal Wf. Accordingly, it is possible to provide a welding apparatus of a variable voltage control type with so-called constant current characteristics, which feeds the consumable electrode by controlling the active voltage of the wire feeding motor.

[Embodiment 5] FIG. 8 is a block diagram of an embodiment of claim 4 in which the welding method of claim 1 is carried out using a welding current with constant current characteristics. Also in FIG. 8, welding can be performed by utilizing the self-control characteristic inherent to the arc explained in FIG. 7.

(Description of Configuration and Operation) The configuration in FIG. 8 that differs from that in FIG. 1 is as follows. First, a crater processing voltage setting circuit VT outputs a crater processing voltage signal Vt, and a welding voltage setting signal Vs is set to a crater processing voltage signal V by a welding end signal Ts.
t, a crater processing current setting circuit IT that outputs a crater processing current signal It, and a crater processing current that switches a wire feed speed signal Wf, which will be described later, to a crater processing current signal It based on a welding end signal Ts. A switching circuit SW4 is added. Second, output the crater processing holding signal Th in response to the welding end signal Ts, and press the welding end start switch TS again (third time) during the crater processing current energization period, or end the time of the timer in the crater processing holding circuit TH. Crater processing holding circuit T that later stops the crater processing holding signal Th
H, solution retention signal sh and crater treatment retention signal T
h as input, the OR signal Or2 is sent to the supply voltage stop circuit N
An OR circuit OR2 is added that outputs to 0T2. Third, the in-solution retention signal sh and the armature pulse signal M m
1 and outputs the current control energization signal Or3.
Switching the welding voltage control signal Cm2 to the welding current control signal Cm3 by the R circuit 3 and the current control energization signal Or3,
A welding output/pulse switching circuit SW2 is added that outputs the welding output/pulse switching signal SW2 to the drive circuit DV. Fourth, the pulse frequency control circuit VF of FIG.
The monomulti oscillation circuit MM2 and the OR circuit OR1 are omitted, and instead of the base current setting circuit IB that outputs the base current signal 1b, a welding current setting circuit IF that outputs a welding current setting signal If is provided. Fifth, the welding voltage setting circuit S and the crater treatment voltage switching circuit SW3 shown by the dashed-dotted line in this embodiment are not used, and the connections shown by the dashed-dotted line are not made. The crater processing current switching circuit SW4 and the wire feeding control circuit WC shown by dotted lines are connected. Sixthly, instead of the average welding current setting circuit IM, a wire feeding speed setting circuit WF is provided for setting a wire feeding speed signal Vf that provides arc-specific self-control characteristics, and normally this setting circuit WF is unified with the welding current setting circuit IF.

When the welding start/end switch TS is pressed, the hold in solution signal s
h is supplied to the welding output/pulse switching circuit SW2 through the OR circuit OR3, and this circuit SW2 compares the welding current setting signal If with the welding current setting signal If through the pulse current signal switching circuit SWI during welding when the solution hold signal sh continues. Circuit C
M3, and the output welding current control signal Cm3 is sent to the welding output/pulse switching circuit SW2 and the drive circuit D.
The welding current is inputted to the welding output control circuit PS through V, and a welding current having constant current characteristics is outputted to perform welding.

Next, when the welding start/end switch TS is pressed again, the in-solution holding signal sh is stopped, the welding output/nox selection switch SW2 is reset, and the difference between the crater processing voltage Vt and the welding voltage detection signal Vd is The welding voltage control signal Cm2 is input to the welding output control circuit PS through the changeover switch SW2 and the drive circuit DV, and outputs the crater processing voltage. Furthermore, when the in-solution retention signal sh is stopped, the crater processing retention signal Th is output and input to the supply voltage stop circuit N0T2 through the OR circuit OR2.
T2 continues to conduct. At the same time, the retention signal s in the solution
h, the crater processing current switching circuit SW4 is switched, the crater processing current signal It is input to the wire feeding control circuit WC, the wire feeding speed is switched to the speed at which the crater processing current is applied, and the crater processing is performed. be exposed. Note that the output voltage and current characteristics during this cratering treatment are constant voltage characteristics.

After removing the crater, turn the welding start/end switch TS again (3
Crater processing hold signal T by pressing or timer
h stops, the supply voltage Wc to the wire feed motor WM is stopped, and the armature detection voltage Wd gradually decreases to a predetermined value or less, the armature pulse signal M is output in the same way as in the case of FIG. The pulse current switching circuit SWI is switched again by m1, and the pulse signal Ip is outputted to the welding output/pulse switching circuit SW2 through this switching circuit SWI.

Since the above armature pulse signal M m 1 switches this switching circuit SW2 at the same time, the pulse current signal Ip is inputted to the welding output control circuit PS through this switching circuit SW2 and the drive circuit DV, and the pulse current signal Ip is inputted to the welding output control circuit PS through this switching circuit SW2 and the drive circuit DV. A pulse current IPn is applied as shown in FIG.

Subsequently, as in the case of FIG. 1, the pulse current stop signal Tr
is input to the reset terminal S of the flip-flop circuit FFI, the energization signal Ff1 at the output terminal Q thereof is stopped, and the pulse current is stopped. By applying this pulsed current, the molten ball 1b at the tip of the wire separates, so that the molten ball 1b at the tip of the wire does not become large particles and does not stick or burn back. In this example, since the pulse current is not applied during the crater treatment, in order to detach the molten ball from the tip of the wire with only one pulse, the method is different from the above-mentioned example] and example 2. Also, the molten ball at the tip of the wire may become large and is susceptible to fluctuations in welding conditions. Note that in this embodiment, the pulse current signal I
When changing to a pulse current setting circuit IP that disappears after p is energized for a predetermined time, the pulse stop signal generating circuit TR of this embodiment is not necessary.

(Modified example) In FIG. 8, the wire feed speed signal Wf set by the wire feed speed setting circuit WF of the wire feed motor is inputted to the wire feed control circuit WC, and the output feed voltage W
In the embodiment shown in FIG. 8, the connection of the wire feeding speed setting circuit WF shown by the dotted line is disconnected and the connection shown by the dashed line is made. At the same time, by connecting the welding voltage setting circuit VS and the crater voltage switching circuit SW3 shown by the - dotted chain line, instead of the wire feeding speed signal If,
By inputting the welding output control signal (welding voltage control signal) Cm2, which is the difference between the welding voltage setting signal Vs and the welding voltage detection signal Vd, to the wire feeding control circuit WC, the arc voltage of the wire feeding motor is controlled to prevent wear. It is possible to use a so-called constant current characteristic, variable voltage control welding device that feeds the electrode.

[Effects of the present invention] Normally, after the supply voltage to the wire feed motor is stopped by a welding end signal, it is necessary to melt the transient wire feed amount due to the inertia of the wire feed motor and wire feed mechanism. . For this purpose, a known technique has been proposed in which a pulse current is supplied with a timer delay. However, with known technology, the time set by the timer is too short and the height of burnout is large due to the effects of wire feeding speed, wire material, wire diameter, wire guide bending, friction condition, etc. during welding. This may cause the molten ball at the tip of the wire to become large, or cause burnback, especially in welding power sources with constant current characteristics, or conversely, if the wire is too long, the tip of the wire may come into contact with the molten pool, causing welding defects. , sticks may occur.

In the welding method and welding apparatus of the present invention, after the supply voltage to the wire feed motor is stopped by the welding end signal, the transient wire feed is substantially stopped and the armature voltage of the wire feed motor is maintained at a predetermined level. Since the pulse current is applied by detecting that the voltage is below the value, the appropriate timing for applying the pulse current is automatically determined, thereby solving the problems encountered in the known techniques.

Further, in the inventions of claims 2, 3, 5, and 6, in addition to solving the problems of the above-mentioned known techniques, the supply voltage to the wire feed motor is controlled by the welding end signal. After stopping, the pulse current and base current are repeatedly applied, so that the droplet transfer to the wire tip is carried out smoothly, and then the final pulse current is applied to ensure that the wire tip is sufficiently detached. be exposed. In particular, as in the example, if the pulse current application period after the welding end signal is synchronized with the droplet transfer at the tip of the wire, the droplet transfer will always occur even while the final pulse current is being applied. In addition, the molten balls at the tip of the wire become small particles, making it difficult for variations in the size of the molten balls to occur. Furthermore, if the switching cycle between the pulse current and base current applied after the welding end signal is controlled by feedback control of the arc voltage, the arc length becomes large and the arc voltage becomes large. Even if the control tries to work so that the base current energization period becomes longer, it detects that the motor has almost stopped and forcibly applies the final pulse current, so the base current energization period is extended like in the past. It is possible to prevent the arc from burning out transiently, make the molten ball at the tip of the wire small, reduce variations, and improve the next arc start.

[Brief explanation of drawings]

FIG. 1 is a block diagram of Embodiment 1 of the welding apparatus according to claim 6 (in which the welding method according to claim 3 is carried out by pulse welding), and FIGS. 2(A) to 2(J) are FIG. 2 is an explanatory diagram of the operation of the welding device shown in FIG. 1; FIG. 3 is a block diagram of a second embodiment of the welding apparatus according to claim 5 (in which the welding method according to claim 2 is carried out with an output having constant voltage characteristics), and FIG. ) is an explanatory diagram of the operation of the welding device shown in FIG. 3. FIG. 5 is a block diagram of Embodiment 3 of the welding apparatus according to claim 4 (where the welding method according to claim 1 is carried out with an output having constant voltage characteristics), and FIG. 6 (A) and (B ) is an explanatory diagram of the operation of the welding device shown in FIG. 5. FIG. 7 is a block diagram of another embodiment 4 of the welding apparatus according to claim 5 (in which the welding method according to claim 2 is carried out with an output having constant current characteristics). FIG. 8 is a block diagram of another embodiment 5 of the welding apparatus according to claim 4 (in which the welding method according to claim 1 is carried out with an output having constant current characteristics). FIGS. 9(A) to 9(G) are explanatory diagrams at the end of the conventional welding method. FIGS. 10(A) to 10(C) are diagrams illustrating appropriate values of the stop time of the pulse current at the end of welding. 1... Consumable electrode (wire) 1a... Wire tip 1b... Wire tip 2... Welded object 2a... Molten pool 2b... Molten pool surface 3... Arc 4... Electrode tip 4a... ...Electrode tip tip Hb...Height after burning ■...Welding type output current IPI, IF2. IPn = Pulse current We...Feeding voltage Vf...Wire feeding speed Et...Welding output voltage tf...Welding end signal output time (code of configuration) AC...Commercial power supply PS...Welding output Control circuit TS...Welding start/end switch SH...Weld raw holding circuit WM...Wire feed motor WC...Wire feed control circuit IM...Average current setting circuit (constant voltage characteristics/pulse welding) ) NOT2... Feed voltage stop circuit CMI... Armature voltage comparison circuit WE... Armature reference voltage circuit MMI... Mono-multi oscillation circuit TR... Pulse stop signal generation circuit FFI... Flip-flop Welding voltage detection circuit CM2 Welding voltage comparison circuit VS Welding voltage setting circuit VF Pulse frequency control circuit MM2 Monomulti oscillation circuit ORI OR circuit I IP ...Pulse current setting circuit IB...Base current setting circuit (welding current setting circuit) S
WI...Pulse current signal switching circuit ID...Welding current detection circuit CM3...Welding current comparison circuit DV...Drive circuit N0TI...Welding current signal stop circuit SW2, 5W2-1, 5W2-2 ・...Welding output/pulse switching circuit SW3... Crater processing voltage switching circuit SW4... Crater processing current switching circuit VT... Crater processing voltage setting circuit IT... Crater processing current setting circuit TH... Crater processing Holding circuit OR2...OR circuit 2 0R3...OR circuit 3 IF...Welding current setting circuit (constant current characteristics) WF...
Wire feeding speed setting circuit (signal code) Ts...Welding start or end signal Im...Average current setting signal We...Feeding voltage sh...Holding in solution signal Wd...Armature detection voltage We... Armature reference voltage Cm 1... Motor stop signal M m 1... Armature pulse signal Tr... Pulse current stop signal Ffl... Energization signal Vd... Welding voltage detection signal Vs. ...Welding voltage setting signal Cm2...Welding voltage control signal (welding output control signal) V
f... Pulse frequency conversion signal M m 2... Pulse frequency signal Or1... Pulse current switching signal Or2... OR signal Ib... Base current signal Ip... Pulse current signal Is... Current Signal Swl... Pulse base signal (welding current/pulse current signal) Id... Welding current detection signal Cm3... Welding current control signal Dv... Welding output control signal 8w2... Welding output/pulse switching signal Vt... Crater processing voltage signal It... Crater processing current signal Th... Crater processing holding signal Or3... Current control energization signal If... Welding current setting signal Wf... Wire feed speed signal (welding output control signal)

Claims (1)

[Claims] 1. In a consumable electrode arc welding method in which welding is performed by applying a welding current to a consumable electrode that is supplied by supplying a supply voltage to a consumable electrode feeding motor, a welding end switch is activated when a welding start/end switch is activated. The supply voltage of the consumable electrode supply motor is stopped in response to a signal, and then, upon detecting that the armature voltage of the consumable electrode supply motor has become less than a predetermined value, the welding current is switched to a pulse current. A consumable electrode arc welding method that finishes by applying a pulsed current. 2.Consumable electrode feeding In the consumable electrode arc welding method, in which welding is carried out by applying a welding current to the consumable electrode that is fed by supplying a voltage to the motor, the consumable electrode is fed by the welding end signal of the welding start/end switch. While stopping the supply voltage of the motor, the pulse current and the base current are repeatedly applied, and when it is detected that the armature voltage of the consumable electrode transmission motor has become below a predetermined value, the final pulse current is generated. A consumable electrode arc welding method in which the pulse current is stopped after energization. 3. In a consumable electrode arc welding method in which pulse current and base current are repeatedly supplied from a welding power source and a consumable electrode is fed at a preset substantially constant speed for welding, the welding end signal of the welding start/end switch to stop the supply voltage of the consumable electrode supply motor, and then, after detecting that the armature voltage of the consumable electrode supply motor has become less than a predetermined value and supplying the pulse current, stop the pulse current. consumable electrode arc welding method. 4. A consumable electrode arc equipped with a welding output control circuit that receives a welding output control signal as input and outputs a welding current, and a wire feeding control circuit that supplies a consumable electrode feeding voltage to a consumable electrode feeding motor. In the welding device, after stopping the feed voltage in response to a welding end signal, an armature voltage comparison circuit outputs a motor stop signal when an armature detection voltage of the feed motor becomes a predetermined value or less, and outputs a pulse current signal. a welding output/pulse current switching circuit that switches the welding output control signal to the pulsed current signal in response to the motor stop signal and inputs the signal to the welding output control circuit; A consumable electrode arc welding device that stops the supply voltage, then switches from welding current to pulsed current in response to a motor stop signal, and then finishes applying the pulsed current. 5. In a consumable electrode arc welding device equipped with a welding output control circuit that receives a welding output control signal as input and outputs a welding current, and a wire feed control circuit that supplies a feed voltage to a consumable electrode feeder motor, a pulse current A pulse current setting circuit that outputs a signal, a base current setting circuit that outputs a base current, a pulse current signal switching circuit that switches between a pulse current signal and a base current signal in response to a welding end signal and outputs a pulse base signal, a welding output/pulse switching circuit that switches from the welding output control signal to the pulse base signal in response to an end signal and inputs the signal to the welding output control circuit; and an electric motor of the power transmission motor after stopping the supply voltage in response to the welding end signal. An armature voltage comparison circuit that outputs a motor stop signal when the child detection voltage becomes a predetermined value or less, and a pulse stop signal generation circuit that receives the motor stop signal as input and outputs a pulse current stop signal, and according to the welding end signal, Stopping the feed voltage, switching from welding current to pulsed current, and then inputting the motor stop signal to the pulsed current signal switching circuit to energize the final pulsed current signal to energize the final pulsed current, A consumable electrode arc welding method in which the final pulse current is then stopped by a pulse current stop signal. 6. Welding output control that outputs a welding current consisting of a pulse current and a base current by inputting a pulse base signal consisting of a pulse current signal set by the pulse current setting circuit and a base current signal set by the base current setting circuit. In a consumable electrode arc welding apparatus, the consumable electrode arc welding apparatus includes a wire feed control circuit that supplies a consumable electrode feed motor with a feed voltage that feeds the consumable electrode at a preset speed. an armature voltage comparison circuit that outputs a motor stop signal when the armature detection voltage of the power transmission motor becomes equal to or less than a predetermined value after stopping the voltage; and a pulse stop signal that receives the motor stop signal as input and outputs a pulse current stop signal. and a consumable electrode which, after stopping the feed voltage in response to a welding end signal, applies a final pulse current in response to the motor stop signal, and then stops the final pulse current in response to a pulse current stop signal. Arc welding equipment.