JPH04210872A - Consumable electrode arc welding control method - Google Patents

Abstract

PURPOSE:To prevent sticking of a consumable electrode by unitary controlling both currents to change over to an anti-sticking current corresponding to its value at the time of completing welding by a welding current. CONSTITUTION:With control of consumable electrode arc welding, the feed voltage Wc of a consumable electrode feed electric motor WM is stopped by stop of an action command sill Ts at the time of completing welding and the unitary control of welding and the antisticking current is carried out by changing over from the welding current to the anti-sticking current corresponding to a welding current value. Consequently, since the proper anti-sticking current corresponding to welding conditions where the welding current value is determined is sent sticking and burn-back of the consumable electrode can be prevented.

Description

[Detailed description of the invention]

[00011

[Industrial Application Field] The present invention applies a welding current to weld, then applies an anti-stick current and reduces the size of the molten ball that adheres to the tip of a consumable electrode (hereinafter referred to as wire) at the end of welding. The present invention relates to a consumable electrode arc welding control method that switches between welding current and anti-stick current in order to improve the next arc start. [0002] One of the prior art techniques (hereinafter referred to as prior art 1) will be explained with reference to FIG. 1. Generally, in the consumable electrode arc welding control method, at the end of welding, a welding start/end switch is pressed, and as shown in FIG.
The welding operation command signal Ts is stopped at f, and the welding operation command signal Ts is
), even if the supply voltage Wc to the wire feed motor (hereinafter referred to as wire feed motor) is stopped, even if the motor is equipped with a brake, the inertia of the motor and feed mechanism will cause the wire to (C)
As shown in the figure, the wire feeding speed Wf gradually decreases and stops at 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 becomes 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 wire tip 1a is
The wire may penetrate into the molten pool 2a, causing welding defects, or the tip of the wire may protrude into the molten pool and become welded, resulting in so-called stick, making it impossible to start the next arc. Therefore, conventionally, from the time tf when the feeding voltage We to the wire feeding motor shown in FIG.
As shown in , the output voltage of the welding power source (hereinafter referred to as welding output voltage) E is adjusted by providing time delays (hereinafter referred to as anti-stick period) Tri to Tr3 using a timer or the like.
Anti-stick is performed to melt this transient wire feed rate by stopping t. 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 period, the wire will melt even after the wire has stopped, increasing the arc length. , the arc voltage increases transiently due to the so-called burning of the arc, approaches the no-load voltage of the welding @ source, and the arc automatically extinguishes. Therefore, when using a welding power source with constant voltage characteristics, the electrode tip tip 4a and the shortened wire tip 1a due to the burning of the arc.
Although the problem of so-called burnback, in which the wires and wires are welded together, does not occur, a molten ball is generated at the tip of the wire due to the burning of the arc, and if this molten ball becomes large, the next arc start cannot be performed properly. In this way, in Prior Art 1, after the stop time tf of the welding operation command signal, as shown in FIG. In the termination method, the height of the arc flares up,
There was a problem that the molten ball at the tip of the wire became large. Therefore, in order to reduce the particle size in a power supply with constant voltage characteristics, a method has been proposed in which a pulse current is superimposed on the anti-stick period (hereinafter referred to as prior art 2). [0003]

[Problem to be solved by the invention] When anti-stick,
As shown in FIG. 2(E), in conventional technology 2 in which a pulsed current Ir is superimposed, in particular, in the MIG aku welding method for aluminum, the specific heat and specific gravity are smaller than steel and it is easy to melt. When welding using an electric current, the molten ball tends to become large, and since a pulse current is superimposed on the welding current, the average value of the anti-stick current Ir becomes higher than the welding current value Ia.
The weld bead width at the end of the weld, that is, the crater, becomes larger, and solidification cracking is more likely to occur in the crater area.
When welding thin plates, welding tends to occur at the end of the weld. In other words, in Prior Art 2, since there is no unified control in which the welding current value and the anti-stick current correspond to each other, the welding current value is determined to be an appropriate anti-stick current corresponding to the welding conditions for which the anti-stick current value is determined, that is, the first Second, the wire does not stick or burn back, and an appropriate protrusion length with little variation remains; second, the molten ball does not become large; and third, there is no solidification cracking at the weld end and the weld end when welding thin plates. There is a problem in that it is not possible to obtain an anti-stick current that does not cause melting of parts. [0004]

[Means for Solving the Problems] In order to solve the above problems, the present invention is constructed by the following means. Claim 1
According to the invention, a welding current having a substantially constant voltage characteristic or a constant current characteristic is supplied to feed a consumable electrode at a substantially constant speed set in advance for welding, or a welding current is supplied from a welding power source having a substantially constant current characteristic. In a consumable electrode arc welding control method in which the consumable electrode is supplied and the consumable electrode is fed at a speed such that the arc voltage becomes a substantially constant value (-)
This is a welding method in which the supply voltage WC of the wire feed motor is stopped by stopping the welding operation command signal Ts, the welding current is switched to an anti-stick current corresponding to the welding current value, and the energization is then terminated. . The invention of claim 2 is:
In the same welding control method as in claim 1, by stopping the welding operation command signal Ts, the feeding voltage Wc of the wire feeding motor is reduced.
By stopping the welding current and switching from the welding current to the pulse current value or base current value or pulse width or pulse frequency or base current value of the anti-stick current, or a current whose two or more correspond to the welding current value, the welding current and This is a welding control method that centrally controls the anti-stick current. The invention according to claim 3 is a welding control method in which the welding current and anti-stick current are centrally controlled by switching from the welding current to the current in which the anti-stick current according to claim 2 transfers one droplet per pulse. According to the fourth aspect of the invention, when the welding current value is large, the average value of the anti-stick current is switched from large to small until the anti-stick current is finished passing (when the anti-stick current is a pulse current, 1 of pulse current value, pulse width, pulse frequency and base current value
This is a welding control method that centrally controls the welding current and anti-stick current by switching two or more of the two. In the invention of claim 5, the anti-stick current is a current corresponding to the welding output voltage setting value or the welding voltage detection value after the supply voltage WC is stopped (when the anti-stick current is a pulse current,
Welding in which the welding current and anti-stick current are centrally controlled by switching to a current in which one or more of the pulse current value, pulse width, pulse frequency, and base current value corresponds to the welding output voltage setting value or welding voltage detection value This is a control method. The invention of claim 6 is a current that corresponds to the pulse current value, pulse width, and base current value of the anti-stick current of claim 2 from the welding current, and the welding voltage set value after the supply voltage is stopped, or This is a welding current control method that centrally controls welding current and anti-stick current by switching to a current with a pulse frequency corresponding to a detected value of welding voltage. The invention of claim 7 is a current that corresponds to one or more of the pulse current value, pulse frequency, and bass current value of the anti-stick current of claim 2 and the welding current value from the welding current, and the supply voltage is stopped. By switching to a current with a pulse width corresponding to the welding voltage setting value or welding voltage detection value after
This is a welding current control method that centrally controls welding current and anti-stick current. [0005]

Embodiment (Explanation of FIG. 3) FIGS. 3A to 3E are explanatory diagrams of operations when the welding control method of claims 2 and 3 is implemented. The same figure (A
) is an explanatory diagram when the welding operation command signal Ts (vertical axis) is stopped at time t=tf (horizontal axis). FIG. 2B is an explanatory diagram when the supply voltage Wc (vertical axis) to the wire feed motor is stopped when the welding operation command signal Ts is stopped. In the same figure (C), when the feeding voltage We is stopped at time t=tf, the wire is transiently fed by a small amount due to the inertia of the electric motor and the feeding mechanism, and the wire feeding speed Wf gradually increases. (vertical axis)
FIG. 12 is an explanatory diagram in which the value decreases and stops from time tl to t3. In the same figure (D), at time t=tr, the welding operation command signal Ts is stopped and the welding output voltage E
FIG. 6 is an explanatory diagram in which t (vertical axis) is switched from the welding voltage average value Ea2 to the anti-stick voltage average value Er2. Same figure (
E) is the welding voltage average value Ea2 at time t=tr
FIG. 3 is an explanatory diagram in which the welding output current I (vertical axis) is switched from the welding current value Ia2 to the anti-stick current Ir2 by switching from the welding current value Ia2 to the anti-stick voltage average value Er2. This anti-stick current Ir2 is centrally controlled in accordance with the welding current value Ia2. For example, when the anti-stick current Ir2 is a pulse current as shown in claim 2, the anti-stick current Ir2
2, the pulse current value Ip2 or the pulse width Tp2 or the pulse frequency f2=1/D2 or the base current value Ib2 or two or more of these correspond to the welding current value Ia2. For example, when the welding current value Ia2 becomes large, the pulse The product of current value Ip2 and pulse width Tp2 also becomes large. Further, as shown in claim 3, if the anti-stick current Ir2 is a current that causes one pulse to transfer one droplet, then the anti-stick current Ir2 is
During this period, the droplet transfer becomes synchronized with the pulse current, and at the end of the anti-stick period, the thickness of the transferring droplet wave becomes uniform, so that the molten ball 1 at the wire tip 1a
b does not become large as in prior art 1 shown in Fig. 5 (Z), but becomes approximately the diameter of a wire as shown in Fig. 5 (A), and the variation in the size of the molten spheres is small. Also, the variation in the wire protrusion length Lm between the welding tip tip 4a and the wire tip 1a or 1b becomes smaller, and the next arc start becomes extremely good. [0006] (Explanation of FIG. 4) FIGS. 4(A) to (E) show that when the welding current value Ial in FIG. 4 is relatively smaller than Ia2 in FIG. FIG. 6 is an explanatory diagram of the operation when the welding control method of item 4 is implemented. 3A to 3C are the same as FIG. 3, so the explanation will be omitted. In the same figure (D), at time t=tr, the welding operation command signal Ts is stopped, the welding output voltage Et (vertical axis) is switched from the welding voltage average value Eal to the anti-stick voltage average value Erl, and the first FIG. 7 is an explanatory diagram of switching to a second anti-stick voltage average value Er2 lower than the first anti-stick voltage average value Erl when the anti-stick period Tra has elapsed. In the same figure (E), at time t=tf, the welding voltage average value Ea
By switching from l to the first anti-stick voltage average value Er2, the welding output current (vertical axis) changes to the welding current value I
FIG. 12 is an explanatory diagram showing that when the first anti-stick current Irl is switched from al to the first anti-stick current Irl and the first anti-stick period Tra has elapsed, the first anti-stick current Irl is switched to a second anti-stick @ current Ir2. 1st
or the second or both antistick currents Irl and Ir
2 corresponds to the welding current value 1al as shown in claim 1, and as shown in claim 4, from the first anti-stick current Irl having a large average value to the second anti-stick current Irl having a small average value. The anti-stick current is switched to Ir2. For example, when the first and second anti-stick currents Irl and Ir2 are pulse currents as shown in claim 2, the pulse current value Ipl or pulse width Tpl or pulse frequency fl of the first anti-stick current Irl= 4/D1 or the base current value Ibl, or two or more of these correspond to the welding current value Ial. For example, when the welding current value Ial becomes large, the product of the pulse current value Ipl and the pulse width Tp2 also becomes large. Further, the second anti-stick current Ir2 is the same as the description of FIG. 3 described above, so a description thereof will be omitted. In addition, in the same figure,
Trb is the energization period of the second anti-stick, and Ir3
indicates the period from the anti-stick @ energization start time at time t=tf to the anti-stick current energization end time at time t=th. [0007] (Explanation of FIG. 6) FIG. 6 shows the results of investigating the influence of the control method at the end of welding on the arc start at the start of the next welding, and shows the welding current value Ia [A] (horizontal axis) It is a graph comparing the relationship between the amount of spatter generation [gr/so times] and the number of arc occurrences 1 for Prior Art 1, Prior Art 2, and the control method of the present invention. The arc start test conditions were as follows: after starting the arc, the arc could be generated for 3 seconds, then the output voltage was stopped for 10 seconds, and this was repeated 50 times. At this time, the total amount of spatter generated [gr] at a welding current value of 60 to 250 [A] is higher in conventional technology 1 shown by curve Z1, compared to conventional technology 2 shown in curve Z2, and control of the present invention shown in curve A. More than a method. In Prior Art 1, the molten spheres at the end of welding are larger than in the control method of the present invention, making it difficult to start the arc at the start of the next welding. [0008] (Description of FIG. 7) FIG. 7 shows that the control method at the end of welding is performed at the welding end portion (hereinafter referred to as
These are the results of an investigation into the influence of the welding current value Ia [A] (horizontal axis) on the occurrence of cracks (referred to as craters) and the relationship between the welding current value Ia [A] (horizontal axis) and the crater cracking rate CR [%]. This is a graph comparing methods. This crater cracking rate CR is (number of beads with crater cracking) / (number of 20 test weld beads)
100 [%1. The test conditions for the crater cracking rate were: plate thickness 6 [mmml], width SO [mmml], length 300
The welding speed is adjusted so that the welding bead width becomes a substantially constant value of 5 mml (i.e., the welding heat input is constant) using aluminum A 5052 material of 5 mml as the workpiece. When, welding @ flow value 100, 2
20 weld beads were created for each current value of 00 and 300 [A], and the number of crater cracks produced for each 20 weld beads was evaluated as the crater crack rate. As shown in the figure, in conventional technology 2 shown by curve Z2, since a pulse current is superimposed on the welding current, as the welding current value increases, the heat input to the crater increases and the cracking rate increases. It has increased. On the other hand, in the control method of the present invention shown in curve A, the anti-stick current is centrally controlled in accordance with the welding current value and an appropriate anti-stick current is automatically obtained. The rate is zero over a wide range of welding current values, and there is a significant difference in effect from Prior Art 2. [0009] (Description of FIG. 8) FIGS. 8 (Z) and (A) show welding @ flow value Ia [A] in the control method of Prior Art 2 and the present invention, respectively.
(horizontal axis) and plate thickness PT [mml (vertical axis), welding indicated by a white circle indicates a range in which a good welding result with no dropout can be obtained, and welding indicated by an X indicates a range in which a good welding result with dropout is obtained. It is a graph showing the range in which results can be obtained. In the graph shown in the same figure (Z) of conventional technology 2, the welding current value is 50
In [A], if the plate thickness is not 2.5 [mm1 or more, welding will occur, but as shown in the same figure (A),
In the control method of the present invention, welding current value 50 [A]
In this case, good welding results were obtained with no melt drop-off up to a plate thickness of 1.0 mm. The welding control method of the present invention enables good welding without melting at the welding end portion when welding a thin plate with a plate thickness of 1.0 mm. [0010] (Description of FIG. 9) FIG. 9 is a block diagram of an embodiment of a welding apparatus that implements the welding control method according to claims 1 to 6. [00111 (Explanation of configuration) In the figure, a commercial power supply AC is input, and welding current and anti-stick current are supplied from a welding output control circuit PS between the electrode tip 4 of the consumable electrode 1 and the workpiece 2. Generate arc 3. The consumable electrode 1 is the wire feed motor W
It is supplied by a wire feed roller WR rotated by M. The welding current setting circuit IM outputs a welding current setting signal Im for setting the average value Ia of the 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. The supply voltage switching circuit SW6 is connected to a welding operation command circuit TS to start welding.
When the welding operation command signal Ts is input from the contact a
The feed voltage Wc is connected to the wire feed motor WM
The supply voltage is then stopped when the welding operation command signal is stopped to complete welding. The feed speed comparison circuit CMI converts the speed detection voltage Wd output from the speed detector WD of the wire feed motor WM into the welding current setting circuit IM.
The welding current setting signal Im is compared with the welding current setting signal Im, and a feeding speed comparison signal Cml corresponding to the difference is output. The welding current magnitude determination circuit CPI outputs an anti-stick (hereinafter referred to as AS) timer switching signal Cpl when the welding current setting signal Im is inputted and is larger than a predetermined current value. The AS start circuit N0T1 inputs the welding operation command signal Ts, and when the signal Ts stops, outputs the AS start signal NIL.
Output. The AS timer switching circuit SWI is a circuit that outputs the AS start signal N11 as the switching AS large current timer signal Sla or the switching AS small current timer signal Slb, and when the AS timer switching signal Cpl is input, the AS timer switching circuit SWI outputs the AS start signal N11 as the switching AS large current timer signal Sla or the switching AS small current timer signal Slb. Switch. The AS small current timer TML uses the signal Slb
When the time limit is input, a time limit count is started, and after the time limit count ends, an AS small current energization signal Tml is output. The AS large current timer TMH starts counting the time limit when the switching AS large current timer signal Sla is input, and after the counting of the time limit ends, the AS large current timer switching circuit TMH starts counting the AS large current energizing signal Tmh. Output. The AS switching small current timer TMJ starts counting the time limit when the signal Tmh is input, and outputs the AS switching small current energization signal Tmj after the time limit counting ends. A
S switching signal output circuit ○R2 is AS small current energization signal Tm
! Alternatively, when either the AS large current energization signal Tmh or the AS switching small current energization signal Tmj is input, the AStf operation signal ○r2 is output. The welding voltage setting circuit VSI outputs a welding voltage setting signal VSI. The AS high voltage setting circuit ASH outputs an AS high voltage setting signal Ash. A.S.
The low voltage setting circuit ASL outputs an AS low voltage setting signal Asl. The AS setting voltage switching circuit SW2 is connected to the A of the B contact.
This is a circuit that outputs a switching AS@pressure signal s2 that switches between the S low voltage setting signal Asl and the AS high voltage setting signal Ash of the a contact, and when the AS large current energization signal Tmh is input, the a contact is switched. Change. The setting voltage switching circuit SW3 is b
This is a circuit that outputs a switching voltage setting signal S3 by switching the welding voltage setting signal Vsl of the contact and the switching AS@pressure signal S2 of the a contact, and switches to the a contact when the AS operation signal ○r2 is input. . The pulse current value setting circuit IPI that forms the AS current receives the welding current setting signal Im as an input.
A pulse current value signal Ipl corresponding to the signal Im is output. The base current setting circuit IBI receives the welding current setting signal Im and outputs a base current setting signal Ibl corresponding to the signal Im. Pulse current setting signal Ipl
, the base current setting signal Ibl, the pulse width of the pulse frequency signal Vf1 and the pulse width frequency control signal Dfl, which will be described later, are set to values that allow one droplet to be transferred per pulse using a fixed, semi-fixed or variable adjuster (not shown). can do. The output voltage comparison circuit CM2 compares the output voltage detection signal Vd of the output voltage detection circuit VD and the switching output setting signal S3 of the setting output switching circuit SW3, and generates an output control signal C of the difference.
Output m2. The pulse frequency conversion circuit VFI that controls the ASfi flow outputs a pulse frequency signal VH corresponding to the pulse period in response to the output control signal Cm2. The pulse width frequency signal generation circuit DPI generates a welding current setting signal I.
When m and the pulse frequency signal Vfl are input, the pulse width frequency control signal Dfl is output. The pulse/base signal switching circuit SW5 has a pulse width frequency control signal Df.
Each time 'l is input, the base current signal 1bl set by the base current setting circuit IBI and the pulse current value signal Ipl set by the pulse current value setting circuit IPI are switched and the AS output control signal S5 is output. do. The welding/AS output switching circuit S~v4 outputs the output control signal C[[12
This circuit switches between the AS output control signal S5 of the a contact and outputs the switching output control signal S4, and switches to the a contact when the AS operation signal ○"2 is input. Output command circuit ○I 1 (well, when welding operation command signal Ts or AS operation signal ○"2 is input, output command signal ○r1 is input to welding output control circuit PS. [0012] (From the start of welding to Operation explanation)
Referring to FIG. 9, the operation of the welding apparatus implementing the control method of the present invention from the start of welding to during welding will be described. In the same figure, each switching circuit SWI to SW5 and the switching circuit SW
6, when no switching signal is input to each switching or opening/closing circuit, each contact is connected to the b side. When the welding operation command signal Ts is output from the welding operation command circuit TS,
The feed voltage switching circuit SW6 is sewn to the a contact, the feed voltage Wc is supplied to the feed motor WM, and the wire 1 is fed. When the welding operation command signal Ts is output, A
Since the S start circuit N0T1 does not output the AS start signal Nfl, the AS operation signal ○r2 is also not output. Therefore, the welding voltage setting signal Vsl changes from the setting voltage switching circuit S to
(2) It is input to the output voltage comparator circuit CM2 through the b contact of 3. On the other hand, the welding/AS output switching circuit SW4 is
'] Since the operation signal ○r2 is not output, it is connected to the b contact. Therefore, the output control signal Cm2 is input to the welding output control circuit PS. In addition, the welding operation command signal Ts is transmitted through the output command circuit ○R1 to the output command signal O.
Since rl is input to the welding output control circuit PS, the circuit P
S outputs the output voltage Ea2 shown in FIG. 3(D) corresponding to the welding voltage setting signal Vsl, and outputs the output current Ia2 shown in FIG. 3(E).
Welding work is performed by applying electricity. [0013] (Description of welding completion operation when the welding current is small) In FIG. 9, when the welding current is small, the welding current magnitude discrimination circuit CP1 does not output the AS timer switching signal Cpl, so the AS timer switching circuit SW1 remains connected to the b contact. In order to finish welding, when the welding operation command signal Ts is stopped at time t=tr in FIG. 3(A), the feed voltage switching circuit SW6 returns to the b contact.
As shown in the figure (B), since the feed voltage ~vc is no longer supplied to the feed motor WM, as shown in the figure (C), the wire feed speed Wf is reduced due to the inertia of the feed motor WM. decreases. On the other hand, when the welding operation command signal Ts stops, the AS start circuit N0T1 outputs the AS start signal Nil, and the AS starts through the b contact of the AS timer switching circuit SWI.
It is input to the small current timer TML. This timer TML outputs an AS small current energization signal Tml, and the AS switching signal output circuit OR2 outputs an AS operation signal Or2. The set voltage switching circuit SW3 is switched to the a contact point by this signal Or2. Further, since there is no input signal to the AS large current timer TMH, the AS large current energization signal Tmh is not output, and therefore the AS setting voltage switching circuit SW2 remains connected to the b contact. Therefore, the AS low voltage setting signal Asl of the AS low voltage setting circuit ASL is input to the pulse frequency conversion circuit VFI through the AS setting voltage switching circuit SW2, the setting voltage switching circuit SW3, and the output voltage comparison circuit CM2. The pulse current value setting circuit IPI and the base current setting circuit IBI input a pulse current value signal Ipl and a base current signal Ibl respectively corresponding to the welding current setting signal Im to the pulse base signal switching circuit SW5. The pulse width frequency signal generation circuit DPI generates a pulse width frequency control signal Df of a pulse frequency and pulse width corresponding to the pulse frequency signal Vfl and the welding current setting signal 1m.
Output l. The pulse/base signal switching circuit SW5 is
The pulse current value signal Ipl and the base current signal Ibl are switched at a pulse frequency determined by the pulse width frequency control signal Dfl to output an AS output control signal S5 forming the waveform shown in FIG. 3(E). Welding/AS output switching circuit SW4 is A
Since the S operation signal Or2 is input and connected to the a contact, the AS output control signal S5 is input to the welding output control circuit PS.
is input. Furthermore, although the welding operation command signal Ts is stopped in the output command circuit ORI, the AS operation signal Or2
is input, the output command signal Orl is output. Since this signal 0 "1 is input to the welding output control circuit PS, the circuit PS outputs the AS@S current Ir2 of FIG. 3(E) corresponding to the AS output control signal S5 to reduce the crater and the wire tip. When the time limit of the AS small current timer TML described above ends, the AS small current energization signal Tml stops. By stopping the signal Tml, the AS operation signal Or2 stops, and the output Since the command signal Orl stops, the AS current Ir
2 stops, all operations are completed, and the state returns to the standby state for starting welding. [0014] (Description of welding completion operation when the welding current is large) In FIG. 9, when the welding current is large, the welding current magnitude discrimination circuit CPI outputs the AS timer switching signal Cpl, so the AS timer switching circuit Switch SWI to a contact. In order to finish welding, at time t=tf in FIG. 4(A), when the welding operation command signal Ts is stopped, as explained in FIG. 3, the feed voltage Wc is stopped, and
The AS start signal Nil is input to the A, S large current timer TMH through the a contact of the AS timer switching circuit SW1. This timer TMH outputs an AS large current energization signal Tmh, and the AS switching signal output circuit OR2 outputs an AS operation signal ○[2. The setting voltage switching circuit SW3 is set to a by this signal ○r2.
Switched to contact. In addition, AS setting voltage switching circuit SW
2 is switched to the a contact point by the AS large current energization signal Tmh. Therefore, the AS high voltage setting signal Ash of the AS high voltage setting circuit ASH is
and setting voltage switching circuit SW3 and output voltage comparison circuit CM
2 to the pulse frequency conversion circuit VFI. Hereinafter, the AS output control signal S5 is generated in the same operation order as when the welding current is small as described above, but when the welding current is large, the AS output voltage setting signal is the AS high voltage setting signal Ash. Therefore, the output control signal Cm during AS operation
2 is larger when the welding current is large than when the welding current is small, so the frequency of the pulse frequency signal Vfl becomes higher, and as a result, the pulse frequency of the ASW flow is higher than that of Fig. 3 (E The pulse frequency of the large current AS current Irl in FIG. 4(E) is higher than the pulse frequency of the AS@S current Ir2 in ), and therefore D2>Di. Next, when the time limit of the AS large current timer TMH ends, the AS large current energization signal Tmh is stopped, and the AS setting voltage switching circuit SW2 returns to the b contact, and the AS low voltage is set from the AS high voltage setting signal Ash. The switching voltage setting signal S3 switched to the signal Ash is input to the pulse frequency conversion circuit VFI through the output voltage comparison circuit CM2. In addition,
At this time, the AS switching small current timer TMJ starts counting the time limit from time t=tg when the AS large current timer signal Tmh stops, but until the time limit counting ends,
Since the AS switching small current energization signal Tmj is output to the AS switching signal output circuit ○R2, the AS operation signal Or2 is continuously output. The above pulse frequency conversion circuit V
FI outputs a pulse frequency signal Vfl corresponding to the AS low voltage setting signal Asl to a pulse width frequency signal generation circuit DPI.
Enter. Therefore, the AS output control signal S5 is switched to a pulse signal with a frequency similar to the AS@S current Ir2 shown in FIG. 3(E), and the AS@ current in FIG. 4(E) is switched from Irl to Ir2. By switching, A in Fig. 4(E)
After applying the S@S current Ir2 to prevent the molten ball from becoming larger at the tip of the wire, the AS switching small current timer TMJ described above is applied.
When the time limit count ends, the AS operation signal "2" stops due to the stop of the AS switching small current energization signal Tmj,
Since the output command signal Orl is stopped, the AS current Ir2 is stopped, all operations are completed, and the state returns to the standby state for starting welding. In the embodiment shown in FIG. 9 above, claims 1 to 6
All of the welding control methods of the embodiment of FIG. One or more of the following configurations may be implemented. (00151 (Description of FIG. 10) FIG. 10 is a block diagram of an embodiment of a welding apparatus that can implement claims 1 to 5 and claim 7. The control method of FIG. Cm2 is input to the pulse frequency conversion circuit VFI, and the AS high voltage setting signal Ash
The frequency of the pulse frequency signal Vfl is switched by the AS period Tra and the AS period rb of the AS low voltage setting signal ASh, so that, for example, the ASS current Ir color I in FIG.
r2. In contrast, Figure 1
In the control method of 0, the welding current setting signal I [0 is input to the pulse frequency conversion circuit VFI, so the pulse frequency signal VII is the same as the AS period T with the AS high voltage setting signal Ash.
It is not switched by ra and the AS period Trb of the AS low voltage setting signal Asl. The control method of FIG. 10 inputs the output control signal Cm2 and the pulse frequency signal Vfl to the pulse width frequency signal generation circuit DPI, and sets the AS period Tra of the AS high voltage setting signal Ash and the AS low voltage setting signal Asl.
The configuration is such that the pulse width is switched depending on the AS period ra to switch to, for example, the AS@S current Ir3Ir2 shown in FIG. 11(E). [0016]

[Effects of the Invention] According to the control method of the present invention, unified control is performed in which the welding current value and the anti-stick current correspond to each other. By energizing, firstly, the wire does not stick or burn back, and an appropriate protrusion length with small variations can be obtained after the arc extinguishes.Secondly, the molten sphere does not become large and has a diameter approximately equal to the diameter of the wire. Thirdly, there is no solidification cracking at the end of the weld.
Two important improvements can be made at the same time, and as a result, the arc can be started instantaneously at the start of the next welding, so there will be no melting failure or spatter caused by insufficient heat input at the start of welding. In addition, it is possible to prevent melt drop at the weld end portion in thin plate welding, which is becoming increasingly important year by year.

[Brief explanation of the drawing]

1] (A) to (E) in FIG. 1 respectively show welding operation command signal Ts, feed voltage Wc, wire feed speed Wf, welding output voltage Et, and welding output current ■ in the control method of Prior Art 1; FIG.

FIG. 2 shows (A) to (C) and (E) in FIG. 1 in the control method of Prior Art 2.
It is a figure showing the same time course as E).

[Fig. 3] (A) to (E) in Fig. 3 are (, A) in Fig. 1 when the set welding @ current is small in the control method of the present invention.
It is a figure showing the same time course as thru|or (E).

FIG. 4 (A) to (E) in FIG. 4 are diagrams showing a time course similar to (A) to (E) in FIG. 1 when the set welding current is a large current in the control method of the present invention; It is.

FIG. 5 (Z) is an explanatory diagram showing that large molten spheres adhere to the tip of the wire in the prior art, and (Z) in FIG.
A) is an explanatory diagram showing the attachment of small molten spheres in the control method of the present invention.

[Figure 6] Figure 6 shows welding current value Ia and spatter generation amount SP.
It is a graph comparing the relationship between the conventional technology 1, the conventional technology 2, and the control method of the present invention.

[Figure 7] Figure 7 shows welding current value Ia and crater cracking rate CR
3 is a graph comparing the relationship between the conventional technique 2 and the control method of the present invention.

[Fig. 8] (Z) and (A) of Fig. 8 show the range in which melt drop occurred and the occurrence of welding with respect to the welding current value ■ and the plate thickness PT in the conventional technology 2 and the control method of the present invention, respectively. FIG.

FIG. 9 is a block diagram of an embodiment of a welding apparatus implementing the control method of the present invention.

FIG. 10 is a block diagram of another embodiment of a welding apparatus implementing the control method of the present invention.

11 is a diagram showing the time course of the output current I corresponding to (E) of FIG. 3 when the control method of the present invention is implemented using the welding apparatus of FIG. 10.

[Explanation of symbols]

(Symbols in FIGS. 3 and 4) Ts Welding operation command signal Wc Feed voltage wr Wire feed speed El Welding output voltage ■ Welding output current I at, I a2 Welding current value I rL,
Ir2. I r3 Anti-stick current tr
Time when welding operation command signal is stopped (when welding is completed) Ip
l, Ip2 Pulse current value Tpl, Tp2 Pulse width Ibl, Ib2 Base current value Di, D2 Pulse period (DI = 1/fl, D2
= 1/f2 where fl and f2 are pulse frequencies) Eal. E rl. a2 r2 Welding voltage average value Anti-stick voltage average value rl T r2゜r3 Anti-stick period

[Procedural amendment]

[Submission date] July 3, 1991

[Procedural amendment 1]

[Name of document subject to amendment] Specification

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction details]

FIG. 2 is a diagram showing the same time course as (A) to (C) and (E) of FIG. 1 in the control method of Prior Art 2;

[Procedural amendment 2]

[Name of document subject to amendment] Specification

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction details]

FIG. 5 is an explanatory diagram showing that large molten spheres adhere to the tip of a wire in the prior art and an explanatory diagram showing that small molten spheres adhere to the control method of the present invention.

[Procedural amendment 3]

[Name of document subject to amendment] Specification

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction details]

FIG. 8 is a graph showing the range in which melt drop occurs and the range in which it does not occur with respect to the welding current value ■ and the plate thickness PT in the control method of Prior Art 2 and the present invention.

Claims (7)

[Claims] [Claim 1] After welding by applying a welding current to a consumable electrode that is supplied by supplying a supply voltage to a consumable electrode feeding motor, the consumable electrode is fed by inertia after the supply voltage is stopped. In a consumable electrode arc welding control method in which welding is completed by passing an anti-stick current that melts the welding amount, the supply voltage of the consumable electrode supply motor is stopped by stopping the operation command signal at the end of welding, and the welding current is A consumable electrode arc welding control method, wherein the welding current and the anti-stick current are centrally controlled by switching from the welding current value to the anti-stick current corresponding to the welding current value. 2. The consumption according to claim 1, wherein the anti-stick current corresponding to the welding current value is a current to which the welding current value corresponds to one or more of a pulse current value, a pulse width, a pulse frequency, and a base current value. Electrode arc welding control method. 3. The consumable electrode arc welding control method according to claim 2, wherein the anti-stick current corresponding to the welding current value is a current that causes one droplet to transfer per pulse. 4. When the welding current value is large, the anti-stick current corresponding to the welding current value is equal to the average value of the anti-stick current between the stop of the supply voltage and the end of the anti-stick current application. 2. The consumable electrode arc welding control method according to claim 1, wherein the current is switched from high to low. 5. The consumable electrode arc welding control method according to claim 1, wherein the anti-stick current corresponding to the welding current value is a current corresponding to the welding output voltage value after the supply voltage is stopped. [Claim 6] The anti-stick current corresponding to the welding current value is a current in which the welding current value corresponds to one or more of the pulse current value, pulse width, and base current value, and the anti-stick current corresponds to the welding current value, and the anti-stick current corresponds to the welding current value, and 3. The consumable electrode arc welding control method according to claim 2, wherein the current has a pulse frequency corresponding to a subsequent welding voltage output value. 7. The anti-stick current corresponding to the welding current value is one of the pulse current value, pulse frequency and base current value.
3. The consumable electrode arc welding control method according to claim 2, wherein the current has a pulse width corresponding to the welding voltage output value after the supply voltage is stopped.