JPH04305374A - Pulse mag welding arc start control method - Google Patents

Abstract

PURPOSE:To provide a pulse MAG welding arc start control method to change periodically the arc voltage or the arc voltage and a welding current to change the arc length periodically. CONSTITUTION:In the pulse MAG welding arc start control method where a first pulse current group P1, P1,... with the small arc length Lt and a second pulse current group P2, P2,... with the larger arc length Lr than the arc length by energizing of this first pulse current group are changed over each other periodically to execute energizing, it is characterized that an arc is started by energizing a third pulse current group P3, P3,... with an average value (Ip2XTp2).f2 between an average value (Ip1XTp1).f1 of a pulse current of the first pulse current group with the small arc length Lt and an average value (Ip2XTp2).f2 of a pulse current of the second pulse current group with the large arc length Lr and then, the first and second pulse current groups are changed over each other periodically to execute energizing.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a pulse MAG welding arc star that periodically changes arc voltage or arc voltage and welding current in order to periodically change arc length.
The present invention relates to a control method.

0002

BACKGROUND OF THE INVENTION In recent years, aluminum and aluminum alloys (hereinafter referred to as aluminum) have come to be widely used for the interior of building structures, vehicles, transportation equipment, and the like. In order for these welded joints to directly form the external surfaces of these structures, it goes without saying that welding strength is required for welded joints, but also that the appearance of the weld bead be good. There is. Therefore, as an arc welding method that produces a good weld bead appearance, the TIG arc welding method in which filler wire is added is widely adopted, but this TIG arc welding method has a slow welding speed. Production efficiency is poor. Therefore, recently, proposals have been made to obtain the same regular wave-shaped weld bead appearance as the TIG arc welding method by using the pulsed MIG arc welding method.

[0003] As one of the cases, the present applicant filed a patent application No. 2-1
As shown in FIG. 1, which is the block diagram described in 02102 (hereinafter referred to as the prior application) with the addition of a hot start current energizing circuit, the first arc voltage setting circuit VS1
The arc voltage setting signal Vs1 and the second arc voltage setting signal Vs2 of the second arc voltage setting circuit VS2 are connected to the welding condition switching signal (hereinafter referred to as "switching circuit") of the welding condition switching circuit (hereinafter referred to as "switching circuit") HL. By switching at the switching frequency F of Hl (referred to as a switching signal), the hot start current Ih and the first and second pulse current groups shown in FIGS. 2(B) and 3(B) are energized, and this pulse current Figure 2
As shown in FIGS. 3(A) and 3(A), the first arc length Lt and the second arc length Lr are switched.

[0004] Such a MIG arc welding method in which the arc voltage or the arc voltage and welding current are periodically changed, especially the pulsed MIG arc welding method of the earlier application explained in FIG. In addition to the above-mentioned regular scale-like bead appearance obtained for aluminum, ■ regular scale-like bead appearance obtained for copper or copper alloys, and ■ crystal grain improvement for aluminum. ■ Less blowholes occur compared to aluminum; ■ Less likely to burn through when butt welded, even if the gap between the butts becomes large. ■In lap fillet welding, even if the overlap gap becomes large, one side melting is less likely to occur. ■For stainless steel, the penetration shape can be controlled, and the welding bead penetrates in the direction of progress. It is expected that the range of application will expand, as the depth is approximately constant.

0010

[Problem to be solved by the invention] MI that is usually performed
G arc welding method and MAG arc welding method (hereinafter referred to as M
(referred to as AG welding), Fig. 2 (A) and Fig. 3 (A
), when the tip 1a of the consumable electrode (hereinafter referred to as wire) 1 is brought into contact with the workpiece 2 to generate an arc 3, as shown in FIGS. 4(A) to 4(C), In the welding start portion 5t, the workpiece 2 to be welded has not yet been sufficiently heated and melted, so that the fusion between the weld metal 5 and the workpiece 2 is relatively poor. In particular, materials with high thermal conductivity mainly composed of aluminum, copper, etc. have poor fusion between the weld metal 5 and the workpiece 2, and as shown in FIG. The height of the excess 5r of the do is shown in the same figure (
As shown in Fig. B), the weld bead width 5w is larger than that of a normal welded part, and as shown in Fig. (C), it is smaller, and as shown in Fig. 5u is likely to occur.

Referring to FIGS. 2(A) to (C) and FIGS. 3(A) to (C), arc The following describes the state when the computer is started. In FIG. 2(A), as shown in FIG. 2(C), welding is started when the arc length determined by the first arc voltage setting signal Vs1 with a small arc voltage setting value Vs is Lt. It is a figure which shows the positional relationship of the wire tip 1a and the to-be-welded object 2 at the time of doing so. In the same figure (A), a hot start current Ih is applied from time ts1 at which the arc starts to time ts2, and after a period T1 to be described later has elapsed, a second It is switched so that the arc length Lr is determined by the arc voltage setting signal Vs2. The same figure (B) shows the pulse frequency f1 determined by the first arc voltage setting signal Vs1 with a small arc length.
(pulse period D1), a preset first pulse current value Ip1, and a first pulse width Tp1. Second arc voltage setting signal Vs
2, the pulse frequency f2 (pulse period D2), the preset second pulse current value Ip2, and the second
Welding current I when the second pulse current group P2, P2, ... with pulse width Tp2 is applied for the second pulse energization period T2
FIG. Figure 3(A) is similar to Figure 2(A).
), welding is started when the arc length determined by the second arc voltage setting signal Vs2 with the large arc voltage setting value Vs is Lr, as shown in FIG. 3(C). It is a figure which shows the positional relationship of the wire tip 1a and the to-be-welded object 2 at the time of doing so. In the same figure (B), after the period T2, the first pulse energization period T
The arc voltage setting value Vs of 1 is switched so that it becomes the arc length Lt determined by the small first arc voltage setting signal Vs1. 2(B) shows the elapsed time ts2 in FIG. 2(B).
and t2 and between t2 and t3 are switched.

As shown in period T1 in FIGS. 2(A) to 2(C), when welding is started from the first arc voltage setting signal Vs1 in which the arc voltage setting value Vs is small, the arc length increases. Lt.
Since the welding temperature is small, there is insufficient heat input, and the workpiece 2 to be welded has not yet been sufficiently heated and melted, so that poor fusion as shown in FIGS. 4(A) to 4(C) described above is likely to occur. Conversely, as shown in period T2 in FIGS. 3A to 3C, the second arc voltage setting signal Vs has a large arc voltage setting value Vs.
When welding starts from step 2, the arc length is large (Lr), so heating and melting begins with the arc spreading, but since the object to be welded has not yet reached a high temperature, oxidation occurs in the aluminum material. Since electron emission from the film is difficult to occur, the cleaning action to remove the oxide film is insufficient and blowholes occur.

[0020]

[Means for solving the problem] Arstar according to claim 1
The control method is to use a small first pulse current group P1, P1,... with an arc length Lt, and an arc length Lr larger than the arc length due to energization of this first pulse current group. In a pulsed MAG welding arc start control method in which the second pulse current groups P2, P2, ... are periodically switched and energized, the average value of the pulse currents of the small first pulse current group when the arc length is Lt. (
Ip1 × Tp1 )・f1 and the average value of the pulse current of the second pulse current group with a large arc length of Lr (Ip2 ×
Tp2 )・f2 average value (Ip2 × Tp2
)・f2 After energizing the third pulse current group P3, P3, ... to start the arc, pulse MAG welding arc start control in which the first and second pulse current groups are periodically switched and energized. It's a method.

In the arc start control method of the second aspect, the third pulse current setting value Ip3s of the third pulse current group is
This is a pulse MAG welding arc start control method in which the first pulse current set value Ip1 s of the first pulse current group and the second pulse current set value Ip2 s of the second pulse current group are set.

In the arc start control method of claim 3, the third pulse width setting value Tp3s of the third pulse current group is set to the first pulse width setting value Tp1s of the first pulse current group and the second pulse width setting value Tp1s of the first pulse current group.
This is a pulse MAG welding arc start control method that is performed between the second pulse width setting value Tp2s of the pulse current group.

In the arc start control method of claim 4, the third pulse current setting value Ip3s of the third pulse current group is
This is a pulse MAG welding arc start control method that calculates from a setting signal Ip1s of the first pulse current setting value and a setting signal Ip2s of the second pulse current setting value.

In the arc start control method of claim 5, the third pulse width setting value Tp3s of the third pulse current group is set by the setting signal Tp1s of the first pulse width setting value and the second pulse width setting value. The pulse MA calculated from the setting signal Tp2s
This is a G welding arc start control method.

[0030]

[Operation] The arc start control method of the present invention will be explained with reference to FIGS. 5 and 6. FIG. 5(A) shows time ts1
The arc is started at , the arc length is set to Lm during the arc start period Ts between time ts2 and t1, and the arc length is set to Lm during the first pulse energization period T1 between time t1 and t2. Set the arc length to Lt,
Further, during the second pulse current conduction period T2 between times t2 and t3, the arc length is set to Lr (however, Lt<Lm
<Lr) is a diagram showing the positional relationship between the wire tip 1a and the workpiece 2 to be welded. The same figure (B) shows the third pulse current group P3 which is applied during the arc start period Ts.
, P3, ..., a first pulse current group P1, P1, ... that is energized during the first pulse energization period T1, and a second pulse current group P2, P2, ... that is energized during the second pulse energization period T2,
FIG. 3 is a diagram showing the time course of repeated welding current I with the first and second pulse current groups. The same figure (C) shows the time period of the setting signal Vs, which is set to the first arc voltage setting value Vs1 during the period ts and T1, and set to the second arc voltage setting value Vs2 during the period T2. FIG.

In the same figure (B), the first pulse current group P1, P1,... is set to the first arc voltage setting value Vs1 and the arc voltage detection value so that the arc length becomes Lt. Vd
It consists of a pulse current having a pulse frequency f1 determined by, a first pulse current value Ip1, and a first pulse width Tp1, and a base current Ib. Second pulse current group P2, P2
, ... are a pulse frequency f2, a second pulse current value Ip2, and a second pulse width Tp2 determined by the second arc voltage setting value Vs2 and the arc voltage detection value Vd so that the arc length becomes Lr. and the base current Ib
It consists of The third pulse current group P3, P3,...
The pulse frequency f3 and the third pulse current are determined by the third arc voltage setting value Vs3 and the arc voltage detection value Vd so that the arc length Lm is between the arc length Lt and the arc length Lr. It consists of a pulse current with a value Ip3 and a third pulse width Tp3, and a base current Ib. Each of these pulse current groups satisfies Ip1 < Ip3 < Ip2 or Tp1 < T
There is a relationship of p3 < Tp2 or Ip1 < Ip3 < Ip2 and Tp1 < Tp3 < Tp2.

Next, another arc start control method of the present invention will be explained with reference to FIG. Figure 6(B) and (
C) is the first pulse energization period T in FIGS. 5(B) and (C).
1 is a diagram showing a time course when the welding current I and the arc voltage set value Vs between the welding current I and the second pulse energization period T2 are reversed. By reversing this, as shown in FIG. 6(A), the arc length L during the arc start period Ts
Next to m, the arc length Lr in the second pulse energization period T2 becomes large, so the arc length Lm in the arc start period Ts is further increased after the workpiece is sufficiently heated and melted. - The weld length Lr becomes large, the heat input becomes large, and the fusion of the workpiece and weld bead is promoted, and in the case of aluminum materials, the cleaning width required for the weld bead width is Reserved from the beginning.

[0040]

[Example] (Explanation of Fig. 7) Fig. 7 (Z) shows the welding result when lap fillet welding was performed using the welding device of the prior application shown in Fig. 1 that does not have the energizing circuit for the third pulse current group. In the figures (Y), (X), and (A), the third pulse current group can be applied. The welding device shown in FIG. 9, which will be described later,
FIG. 4 is a diagram showing welding results when lap fillet welding was performed with the start period Ts set to 0.2 seconds, 0.4 seconds, and 0.5 seconds, respectively. Same figure (X) to (Z) and (A)
The welding conditions are as follows. Welding aluminum material A5052 with a plate thickness of 3 [mm] using aluminum wire A5183 with a diameter of 1.2 [mm] and an average value of welding current of 10
0 [A], arc voltage average value 19 [V], welding speed 40
A welding current of the pulse current group shown in FIG. 5(B) was applied at [cm/min]. Note that the arc lengths Lm and Lt shown in FIG. 5(A) of this example are
and Lr are approximately 5 [mm], 3 [mm] and 7 [mm], respectively.
It was set to [mm].

Arc start period Ts=0 in FIG. 7(Z)
At Ts = 0.2 seconds in the same figure (Y), the surplus 5r and both the upper plate 2a and the lower plate 2b overlap due to considerable fusion failure. There is a considerable portion 5u where 5r and the lower plate 2b are poorly fused. Also, even when Ts=0.4 [seconds] in Fig. 7(X), still
A slight fusion failure part 5u is seen on the lower plate 2b, as shown in Fig. 7(A).
), when Ts=0.5 [seconds], the inclined surface of the extra layer 5r becomes flat, and no fusion defects or undercuts are observed at all. Therefore, in the arc start control method of the present invention, the arc start period Ts needs to be 0.5 seconds or more.

(Explanation of FIG. 8) FIG. 8 (Z), (A), (B
) and (Q) are applied to the workpiece 2 by welding equipment with the arc start period Ts set to 0, 0.5, 1.0, and 1.5 seconds under the same welding conditions as in Fig. 7. weld bead 5
It is a figure which shows the upper appearance of a weld bead when forming a weld bead. The same figure (Z) shows a welding device that does not have the third pulse current energization circuit of the previous application, and the weld bead width 5w at the welding start portion 5t is narrow and the weld bead has a convex shape. This resulted in considerable fusion failure. Same figure (A)
and (B) are Ts=0.5 seconds and 1.0 seconds, respectively.
During this period, a flat weld bead was obtained without any fusion failure occurring at the welding start portion 5t. Furthermore, as shown in FIG. 2(Q), at Ts=1.5 seconds, the weld bead width 5w at the welding start portion 5t is larger than the normal weld bead width. Therefore, the art of the present invention
The appropriate arc start period Ts in the arc start control method is 0.5 to 1.0 seconds.

(Welding apparatus for implementing the arc start control method of the present invention) FIGS. 9, 11, and 12 show a welding apparatus for implementing the arc start control method of the present invention using a pulse MAG welding method. FIG. Further, FIGS. 10(A) to (D) and FIGS. 13(A) to (E) are diagrams showing the time course of output signals of each circuit in FIGS. 9 and 12, respectively, and FIGS. 12 shows a connection diagram of an embodiment of the automatic start voltage setting circuit AVS in the block diagram, and FIG.
6 is the pulse width setting switching circuit TPA in the block diagram of FIG.
FIG. 3 is a connection diagram of the embodiment.

(Explanation of FIG. 9) In FIG. 9, commercial power supply A
C as an input, an output is supplied between the power supply tip 4 of the wire 1 and the workpiece 2 from a welding output control circuit PS having constant voltage characteristics to generate an arc 3. The wire 1 is supplied from a wire feed roller WR rotated by a wire feed motor WM. The average welding current setting circuit IM is the wire feed mode.
An average welding current setting signal Im for setting the average value of the welding current determined by the wire feeding speed of the motor WM is output. The wire feed control circuit WC includes a wire feed speed detector W that detects the signal Im and the rotational speed of the wire feed motor WM.
With the comparison signal Cm1 of the first comparison circuit CM1 that compares the speed detection signal Wd of the wire feed motor WM as an input,
The wire feed voltage Wc is output to. The first arc voltage setting circuit VS1 and the second arc voltage setting circuit VS2 are circuits for setting the arc voltage under the first welding condition and the arc voltage under the second welding condition, respectively. 1 a-
Arc voltage setting signal Vs1 and second arc voltage setting signal V
Output s2. The switching circuit HL outputs a switching signal Hl for switching between the first welding condition and the second welding condition. The arc voltage switching circuit SW1 receives the signal Vs1 by the switching signal Hl.
and Vs2 to output an arc voltage switching signal S1.

The welding current detection circuit ID outputs a welding current detection signal Id corresponding to the welding current I shown in FIG. 10(A) after arc start at time ts2. The third comparison circuit CM3 outputs a welding current energization signal Cm3 that is the difference between the signal Id and the reference signal Vr of the reference signal generation circuit VR, as shown in FIG. 10(C). Arc start time limit circuit (
As shown in FIG. 10(D), TM3 (hereinafter referred to as AS time limit circuit) outputs an arc start completion signal (hereinafter referred to as AS A completion signal) Tm3 is output. The third arc voltage setting circuit VS3 has a third arc voltage set to a voltage value appropriate for arc start between the first arc voltage setting value Vs1 and the second arc voltage setting value Vs2. Outputs arc voltage setting signal Vs3. The arc start welding voltage switching circuit (hereinafter referred to as SW voltage switching circuit) SW5 outputs the third arc voltage setting signal Vs3 connected to contact b until the AS completion signal Tm3 is input. Then, when signal Tm3 is input, it switches to contact a,
The aforementioned arc voltage switching signal S1 is output. Therefore, the switching arc start welding voltage signal (hereinafter referred to as SW voltage switching signal) S5 outputted by this circuit SW5 is as shown in FIG. 10(B).
, the third arc voltage setting signal Vs3 is output, and after the period Ts, the first and second arc voltage setting signals Vs1 and Vs2 are output at the cycle of the switching frequency F of the switching signal Hl.
Output. The second comparator circuit CM2 inputs the signal S5 and the welding voltage detection signal Vd of the welding voltage detection circuit VD and outputs an arc voltage signal Cm2 that is the difference between them.

First and second pulse current value setting circuit IP1
and IP2 output first and second pulse current value setting signals Ip1 s and Ip2 s, respectively. The pulse current value switching circuit SW3-1 changes the signal I by the switching signal Hl.
The switching pulse current value signal Ips is output by switching between p1 s and signal Ip2 s. Base current setting circuit IB
outputs a base current setting signal Ibs. The first and second pulse width setting circuits TP1 and TP2 each have a first
and outputs second pulse width setting signals Tp1 s and Tp2 s. The pulse width switching circuit SW3-3 receives the switching signal H
The signal Tp1 s and the signal Tp2 s are switched by l to output a switching pulse width signal Tps.

[0052] The third pulse current value setting circuit IP3
Third pulse current value setting signal Ip3 suitable for start
Outputs s. The arc start/welding (hereinafter referred to as SW) pulse current value switching circuit SW4-1 outputs the signal Ip3s connected to contact b until the AS completion signal Tm3 is input, and the signal Tm3 After inputting, the contact a switches to output the signal Ips. Therefore, the switching SW pulse current value signal Ipa output by this circuit SW4-1 outputs the signal Ip3s during the arc start period Ts, and after the period Ts, the switching SW pulse current value signal Ipa outputs the signal Ip3s at the period of the switching frequency F of the switching signal Hl. Then, the first and second pulse current value setting signals Ip1 s and Ip2 s are output. Third
The pulse width setting circuit TP3 outputs a third pulse width setting signal Tp3s suitable for arc start. The SW pulse width switching circuit SW4-3 switches the signal Tp3s connected to contact b until the AS completion signal Tm3 is input.
After the signal Tm3 is input, it switches to contact a and outputs the signal Tps. Therefore, the switching SW pulse width signal Tpa output from this circuit SW4-3 is equal to the signal Tp3s during the arc start period Ts.
After the period Ts, the switching frequency F of the switching signal Hl is output.
The first and second pulse width setting signals Tp1 s and Tp2 s are output at a period of .

(Description of operation during arc start period) During the arc start period Ts, the pulse frequency signal generation circuit VF outputs the third arc voltage setting signal Vs3 and the arc voltage detection signal Vd. A third pulse frequency control signal Vf3 is output in response to the arc voltage control signal Cm2 of the difference. During this period Ts, the AS completion signal Tm3 has not yet been input to the SW pulse current value switching circuit SW4-1 and the SW pulse width switching circuit SW4-3, so the circuit SW4-1 outputs the signal Ip3s, and the circuit SW4-3
outputs a signal Tp3s. Therefore, the pulse width frequency signal generation circuit DF outputs the third pulse width setting signal Tp
3s and a third pulse frequency control signal Df3 is output. The pulse base current switching circuit SW2 switches the third pulse current value setting signal Ip3s and the base current setting signal Ibs to the third pulse current value setting signal Ip3s and the base current setting signal Ibs.
Frequency f3 determined by pulse width frequency control signal Df3
The pulse control signal Pf3 is outputted and input to the welding output control circuit PS.

(Explanation of operation after arc start period has elapsed)
After the arc start period Ts has elapsed, the pulse frequency signal generation circuit VF generates the first pulse frequency control signal V under the first welding condition in response to the arc voltage control signal Cm2.
f1 and the second pulse frequency control signal Vf2 under the second welding condition are switched and outputted at the switching frequency F of the switching signal Hl. The pulse width frequency signal generation circuit DF generates a pulse width setting signal Tps and a first pulse frequency control signal Vf1.
A first pulse width frequency control signal Df1 corresponding to the first welding condition and a second pulse width frequency control signal Df2 corresponding to the second welding condition are output. Under the first welding condition, the pulse-based current switching circuit SW2:
The first pulse current value setting signal Ip1s and the base current setting signal Ibs are converted into the first pulse width frequency control signal Df1.
Pulse control signal Pf1 that repeats at a frequency f1 determined by
Then, under the second welding condition, the second
The pulse current value setting signal Ip2s and the signal Ibs are set at a frequency f2 determined by the second pulse width frequency control signal Df2.
A repeating pulse control signal Pf2 is outputted and input to the welding output control circuit PS.

(Explanation of FIG. 11) FIG. 11 shows a second embodiment of the pulse MAG welding arc start control method of the present invention, which has the configuration described in claims 1 and 2. There is. The configuration in this figure that is different from that in FIG. 9 is, firstly, that the configuration of FIG. 9 is simplified, and secondly, that the configuration in FIG. 11, the pulse width is controlled by the signal Cm2 to maintain the arc voltage value at a predetermined value. In the arc start control method of the present invention, in FIG. -1 or ■Second pulse width setting circuit TP2, pulse width switching circuit SW3-3, and third pulse width setting circuit TP
3 and SW pulse width switching circuit SW4-3, and when the switching frequency F is relatively high, for example, 3 [Hz]
In the above case, ■Second arc voltage setting circuit VS2 and arc
Arc voltage switching circuit SW1 and third arc voltage setting circuit VS3
The SW voltage switching circuit SW5 can be omitted. Therefore, in FIG. 11, each of the circuits (2) described above is provided, and the circuits (2) and (2) are omitted.

Next, the second difference is that in FIG. 11, the first to third pulse width setting circuits TP1 to TP in FIG.
3. In place of the pulse width switching circuit SW3-3 and SW pulse width switching circuit SW4-3, the first pulse frequency setting signal F
A first pulse frequency setting circuit FP1 that outputs p1 is provided. Furthermore, the pulse frequency signal generation circuit VF
inputs the signal Fp1 and outputs a pulse frequency signal Vf. Therefore, during the arc start period Ts, the arc voltage control signal Cm2 is equal to the arc voltage detection signal V corresponding to the third pulse current value setting signal Ip3s.
d and the third arc voltage setting signal Vs3 is output, and the first pulse energization period T1 is output.
, a first arc voltage control signal corresponding to the difference between the signal Vd and the signal Vs1 corresponding to the first pulse current value setting signal Ip1s is output, and during the second pulse energization period T2, the second pulse current is A second arc voltage control signal corresponding to the difference between the signal Vd and the signal Vs2 corresponding to the value setting signal Ip2s is output. The pulse width frequency signal generation circuit DF is
As mentioned above, in the period Ts, the third pulse width frequency control signal Df3 is outputted by inputting the third arc voltage control signal Cm2, and in the period T1, the first arc voltage control signal Cm2 is outputted. is input, and the first pulse width frequency control signal Df1 is output, and in period T2, the second arc voltage control signal Cm2 is input, and the second pulse width frequency control signal Df1 is output.
A pulse width frequency control signal Df2 is output.

In the embodiment of FIG. 11 as well, the average value of the pulse currents (Ip1 × Tp1)·f1 of the first pulse current groups P1, P1, ... with small arc lengths and the first pulse current group with large arc lengths The average value of the pulse currents of the two pulse current groups P2, P2,...
The average value between Ip2 × Tp2 )・f2 (Ip3
×Tp3 )・f3 third pulse current group P3, P3
,... After performing arc start control by applying current, by periodically switching the first and second pulse current groups,
The pulse MAG welding arc start control method of the present invention can be achieved. Furthermore, this modification is as follows. With the configuration shown in FIG. 9, when the apparent arc length is switched to Lr>Lm>Lt by pulse frequency control, ■Tp1 = Tp2 = Tp3 and Ip2 > Ip3
＞Ip1 ■ Ip1 = Ip2 = Ip3 and Tp2 ＞
Tp3 >Tp1■Ip2 >Ip3 >Ip1 and Tp2 >Tp3 >Tp1 With the configuration shown in Fig. 11, the apparent arc length can be changed to Lr>Lm>L by controlling the pulse width.
When switching to t, ■ f1 = f2 = f3 and Ip2 > Ip3 > Ip1 ■ Ip1 = Ip2 = I
p3 and f2 > f3 > f1 ■ Ip2 > Ip3 >
f2 > f3 > f1 at Ip1

(Fig. 12
(Explanation) FIG. 12 is a block diagram of a third embodiment of a welding apparatus implementing the pulse MAG welding arc start control method of the present invention. In the figure, a first configuration different from FIG. 9 is that instead of the average welding current setting circuit IM of FIG. 9, a start current setting circuit IM that outputs a start current setting signal Im, and a first welding a first average welding current setting circuit IH that outputs a first welding current setting signal Ih under the conditions;
A second average welding current setting circuit IL outputs a second welding current setting signal Il under the welding conditions, and a switching signal Hl is used to switch between the first welding current setting signal Ih and the second welding current setting signal Il.
A welding current switching circuit SW3 switches at a switching frequency F and outputs a welding current switching signal S3, and an AS completion signal Tm.
3 is input, the start current setting signal Im of contact b is output to the first comparator circuit CM1, and the AS completion signal T
After m3 is input, the start welding current switching circuit (hereinafter referred to as SW current switching circuit) SW4 switches to contact a and outputs the welding current switching signal S3 to circuit CM1.
has been added. This circuit SW4 switches between the start current setting signal Im and the welding current switching signal S3, and outputs a start welding current switching signal (hereinafter referred to as SW current switching signal) S4.

In FIG. 12, a second configuration different from FIG. 9 has the following hot start current energizing circuit added. A hot start current setting circuit (hereinafter referred to as HS current setting circuit) IH outputs a hot start current setting signal (hereinafter referred to as HS current setting signal) Ihs. Hot start time circuit (hereinafter referred to as HS time circuit) TM
2 starts the time limit when the welding current energization signal Cm3 is input, and after the hot start period Th ends, the hot start end signal (hereinafter referred to as HS completion signal) Tm
Outputs 2. The hot start welding current signal switching circuit (hereinafter referred to as HW current switching circuit) SW9 outputs the HS current setting signal Ihs connected to contact b until the HS completion signal Tm2 is input, and when the signal Tm2 is input. After that, it switches to contact a and pulse control signal Pf1
to Pf3 are output.

The welding current signal S9 that the HW current switching circuit SW9 outputs to the welding output control circuit PS is the HS current setting signal Ihs for applying the hot start current Ih during the hot start period Th. During the start period Ts, the pulse control signal Pf3 is for energizing the third pulse current group P3, P3, ..., and during the second pulse energization period T2, the second pulse current group P2,
A pulse control signal Pf2 for energizing P2, . . . during the first pulse energization period T1, a pulse control signal Pf2 for energizing the first pulse current group P1, P1, .
It is f1.

In the block diagram of FIG. 12, the third configuration different from the block diagram of FIG. 9 is the third configuration of the block diagram of FIG.
The third arc voltage setting of the arc voltage setting circuit VS3 is
The setting signals for the first and second arc voltage setting values are input, and the starting voltage setting signal AVS outputted from the automatic starting voltage setting circuit AVS automatically sets the starting voltage setting signal AVS.

FIG. 14 shows the circuit AV in the block diagram of FIG.
FIG. 2 is a connection diagram of an embodiment of S, which is configured with first and second arithmetic circuits OP1 and OP2 and resistors R and 2R, with first and second arc voltage setting signals Vs1 and Vs2 as input, Outputs a start voltage setting signal Avs. The first arithmetic circuit OP1 is an adder with a gain of 1/2, and its output is -(Vs1 +Vs2)/2. The second arithmetic circuit OP2 is an inverting amplifier with a gain of 1 that inverts the output of the circuit OP1, and its output value is (Vs1
+Vs2)/2. In FIG. 15, a fine adjustment setting device VE shown by a dotted line is added to the connection diagram of FIG. 14. By connecting both terminals of the fine adjustment setting device VE to power supplies with voltage values of +Ve and -Ve, the setting range of the start voltage setting signal Avs can be set to 1/2 (Vs1 +Vs2
)±Ve.

(Explanation of FIGS. 14 and 15) FIG. 14 is a connection diagram of an embodiment of the automatic start voltage setting circuit AVS in the block diagram of FIG. - It is a connection diagram in which a fine adjustment setting device is added to the automatic voltage setting circuit AVS.

(Explanation of FIG. 16) In the block diagram of FIG. 12, a fourth configuration different from the block diagram of FIG. 9 is the first to third pulse width setting circuits TP1 to TP3 and the pulse width switching circuit of FIG. SW3-3 and SW pulse width switching circuit S
A pulse width setting switching circuit TPA is used in place of W4-3. FIG. 16 shows the circuit TP in the block diagram of FIG.
A connection diagram of embodiment A is shown. In FIG. 16, the mono multivibrator circuit MMA has terminals 1 to 3,
The pulse frequency control signals Vf1 to Vf3 are inputted and the switching pulse width signal Tps is outputted to the terminal 4. This circuit MMA has a resistance value r1 that determines the time constant.
, r2/2 and r2 resistors R1, R2/2 and R
2 are connected in series, a first switch ASW1 is connected to both ends of the resistor R2/2, and a second switch ASW2 is connected to both ends of the resistor R2. Also, the circuit MM
The first switch ASW1 is off until the AS completion signal Tm3 is input to the terminal 2 of A, and the signal Tm3
When input, it turns on and the resistor R connected across it turns on.
Short 2/2. Furthermore, the switching signal Hl is input to the terminal 3 of the circuit MMA, and the NAN
It is output to D circuit NND. This circuit NND has a signal T
When m3 is input and the switching signal Hl is input, a signal is output to the second switch ASW2, and this second switch ASW2 short-circuits the resistor R2.

Next, the operation of FIG. 16 will be explained. A.S.
As described above, the first switch ASW1 is off and the NAND circuit NND is turned off until the completion signal Tm3 is input.
Since the second switch ASW2 is turned on by the output of , the time constant resistance value of the circuit MMA is r1 + r2/2
Then, the third pulse width setting signal Tp3s is output. When the AS completion signal Tm3 is input, the first switch A
Since SW1 is turned on and the switching signal Hl is stopped during the first pulse energization period T1, the NOT circuit NT1 outputs the signal, and both this signal and the signal Tm3 are sent to the NAND circuit NND. Since the signal is input, the circuit NND stops the signal and the second switch ASW2 turns off, so the time constant resistance value of the circuit MMA is r1 + r2
Then, the first pulse width setting signal Tp1s is output. Furthermore, since the switching signal Hl is outputting a signal during the second pulse energization period T2, the NOT circuit NT1 stops the signal, so the NAND circuit NND outputs the signal, and the second switch ASW2 is turned on. , circuit M
The time constant resistance value of MA becomes r1, and the second pulse width setting signal Tp2s is output. Here, if K is a proportional constant, each setting value is Tp1 = K (r1 + r2)
...(1) Tp2 = Kr1
…(2) Tp3 = K(r1 +r2/2)…(3
), and by substituting (1) and (2) into (3), we get T
The relationship p3 = (Tp1 + Tp2)/2 holds true. Therefore, the first to third pulse widths Tp1 to Tp
3, the resistor with the preset resistance value can be automatically switched.

In the block diagram of FIG. 12, a fifth configuration different from the block diagram of FIG. 9 is that instead of the third pulse current value setting circuit IP3 of FIG. 9, the first and second pulse current value setting signals Ip1s A third pulse current value automatic setting circuit IPA automatically outputs a third pulse current value setting signal Ip3s by inputting the signals Ip2s and Ip2s.

(Explanation of FIG. 13) FIG. 13(A) shows the time t
Hot start period Th from s1 to time ts2
, a hot start current Ih is applied, and a time ts
During the arc start period Ts from time t1 to time t1, the third pulse current group P3, P3,... is applied, and during the second pulse current period T2 from time t1 to time t2, the third pulse current group P3, P3,... is applied.
energizes the second pulse current group P2, P2,..., and at time t
The first pulse energization period T1 from 2 to time t3 is the welding current I that energizes the first pulse current group P1, P1,...
It is a figure showing the time course t of. FIG. 3(C) is a diagram showing the time course t of the welding current energization signal Cm3 outputted by the third comparison circuit CM3. In the same figure (D), time ts1
When the signal Cm3 is input, the timer starts, and after the hot start period Th elapses, the HS completion signal Tm is input.
FIG. 2 is a diagram showing the time course of outputting 2. Same figure (E)
This is a diagram showing a time course in which a timer is started when a signal Cm3 is input at time ts1, and an AS completion signal Tm3 is output after a hot start period Th and an arc start period Ts have elapsed. . The figure (B) shows that the third arc voltage setting signal Vs3 is output until time t1, the second arc voltage setting signal Vs2 is output during the second pulse energization period T2, and the second arc voltage setting signal Vs2 is output during the first pulse energization period. T1
2 is a diagram showing the time course of the arc voltage setting signal Vs which outputs the first arc voltage setting signal Vs1.

[0100]

[Effects of the present invention] The arc start control method of the present invention has the following effects:
The first pulse current group has a small arc length, and the second pulse current group has a large arc length.
By starting the arc at the arc voltage determined by the energization of the third pulse current group to obtain the arc length between the pulse current group and the arc length required at the start of welding, an appropriate arc length can be obtained. The object to be welded is heated and melted by the heat input, and the aluminum material is also treated with a cleaner to remove the oxide film.
Since the cleaning action is performed for 0.5 seconds to 1.5 seconds,
Blowholes do not occur at the welding start part, and even in pulse MAG welding of not only aluminum materials but also steel materials, there is no fusion failure or protrusion at the welding start part. Excessive fill may occur or overflow may occur.
Welding defects such as burlap and undercuts do not occur, and both the appearance and width of the weld bead are stable and the same as the weld bead during welding.

In the arc start control method of claim 4, the setting signal for the first pulse current setting value and the setting signal for the second pulse current setting value are input, and the third pulse current setting signal necessary for arc start is input. A setting signal for the pulse current setting value is automatically generated, and welding is started by energizing the third pulse current group based on the setting signal, so the setting operation by the operator is omitted, preventing erroneous settings or changing the settings. Simplification can be achieved.

In the arc start control method according to the fifth aspect of the present invention, the setting signal for the first pulse width setting value and the setting signal for the second pulse width setting value are input, and the third A setting signal for the pulse width setting value is automatically generated, and welding is started by energizing the third pulse current group based on the setting signal, so the setting operation by the operator is omitted and setting errors can be prevented or settings can be changed. Simplification can be achieved.

[Brief explanation of the drawing]

[FIG. 1] FIG. 1 is a block diagram of a welding device used in the pulse MAG welding method of the previous application in which welding is performed by periodically changing the arc voltage in order to periodically change the arc length. .

[Fig. 2] Figs. 2(A) to 2(C) show the welding process shown in Fig. 2(A) after arc starting by applying a hot start current using the welding equipment shown in Fig. 1, respectively. As shown, welding starts from Lt with a small arc length, then welding starts with Lt with a large arc length.
A diagram showing the positional relationship between the wire tip 1a and the workpiece 2 when switching to r, a diagram showing the time course of the welding current I, and a diagram showing the time course of the set value Vs of the arc voltage setting signal. It is a diagram.

[Fig. 3] Fig. 3 (A) to Fig. 3 (C) show that after applying a hot start current and starting an arc, in contrast to the case of Fig. 2,
As shown in Figure (A), a diagram showing the positional relationship when welding starts from Lr, where the arc length is large, and then switches to Lt, where the arc length is small, and the time of the welding current I. FIG. 2 is a diagram showing a time course of the set value Vs of the arc voltage setting signal; and FIG.

[Fig. 4] Fig. 4 (A) to Fig. 4 (C) are a cross-sectional view and a vertical cross-sectional view of the welding start part when performing an arc start using the welding apparatus of Fig. 1, and a view from above, respectively. It is an external view.

FIG. 5(A) shows a setting value for setting an arc length Lm between a short arc length Lt and a long arc length Lr applied to the arc start control method of the present invention. FIG. 2 is a diagram showing the positional relationship between the wire tip 1a and the workpiece 2 when arc starting. Figure (B) shows the hot start period Th,
3 is a diagram showing the time course of the welding current I applied during the start period Ts, the first pulse current application period T1, and the second pulse current application period T2. FIG. FIG. 3(C) is a diagram showing the time course of the arc voltage setting value Vs in the period Th, period Ts, period T1, and period T2.

FIG. 6(A) is a diagram showing the same positional relationship as FIG. 5(A) applied to another arc start control method of the present invention. FIG. 5(B) is a diagram showing the same time course as FIG. 5(B). FIG. 5(C) is a diagram showing the same time course as FIG. 5(C).

[Fig. 7] Fig. 7 (Z) is a diagram showing the welding results when lap fillet welding was performed using the welding device of the prior application which cannot conduct the third pulse current group, and Fig. 7 (Y) and (X) and (A
) uses a welding device capable of applying the third pulse current group to set the arc start period Ts to 0.
It is a figure which shows the welding result when lap fillet welding was performed for 2 seconds, 0.4 seconds, and 0.5 seconds.

FIG. 8 (Z), (A), (B), and (Q) show that the arc start period Ts is 0, 0.5, 1.0
and 1.5 seconds, and the weld bead is placed on the workpiece 2.
FIG.

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

10A to 10D are diagrams showing the time course of output signals of each circuit in FIG. 9;

FIG. 11 is a block diagram of a second embodiment of a welding apparatus implementing the arc start control method of the present invention.

FIG. 12 is a block diagram of a third embodiment of a welding apparatus implementing the arc start control method of the present invention.

13A to 13E are diagrams showing the time course of output signals of each circuit in FIG. 12. FIG.

14 is a connection diagram of a specific embodiment of the automatic start voltage setting circuit AVS in the block diagram of FIG. 12; FIG.

[Fig. 15] Star with fine adjustment setting device in the block diagram of Fig. 14
FIG. 2 is a connection diagram of a specific embodiment of the automatic voltage setting circuit AVS.

16 is a connection diagram of an embodiment of the pulse width setting condition circuit in the block diagram of FIG. 12; FIG.

[Explanation of symbols]

1 Consumable electrode (wire) 1a Consumable electrode (wire) tip 2 Workpiece to be welded 3 Arc 4 Power supply tip 4a Power supply tip tip 5 Weld metal (weld bead) 5t Welding start part 5r Excess metal 5u Poor fusion part (under -Cut) 5w Weld bead width at welding start part P1, P1,... 1st pulse current group P2, P2
,... Second pulse current group P3, P3,... Third pulse current group T1 First pulse energization period T2 Second pulse energization period Th Hot start period Ts Arc start period D1, D2, D3 1st to 1st 3 pulse period f
1, f2, f3 1st to 3rd pulse frequency I
h Hot start current Ip1, Ip2, Ip3 First to third pulse current values Tp1, Tp2, Tp3 First to third
Pulse width Ib Base current value VS1 to VS3 First to third arc voltage setting circuit Vs1 to Vs3 First to third arc voltage setting value (setting signal) TM2 Hot start (HS) time limit circuit Tm2
Hot start (HS) completion signal TM3 Arc start (AS) time limit circuit Tm3 Arc start (
AS) Completion signal AVS Start voltage automatic setting circuit Avs Start voltage setting signal TPA Pulse width setting switching circuit Tps Switching pulse width signal IPA 3rd pulse current value automatic setting circuit IH Hot start (HS) current setting circuit Ihs HS current setting signal IM Average welding current or start current setting circuit Im
Average welding current or start current setting signal IP3 Third pulse current value setting circuit IB Base current setting circuit TP3 Third pulse width setting circuit SW4 SW current switching circuit S4...SW current switching signal SW4-1 SW pulse current value Switching circuit Ipa Switching SW pulse current value signal SW4-3 SW pulse width switching circuit Tpa Switching SW pulse width signal SW5 SW voltage switching circuit S5 SW voltage switching signal SW9 HW current switching circuit S9 Welding current signal Ip1 s to Ip3 s 1st to Third pulse current value setting signal (current value setting value) Ibs Base current setting signal Tp1s to Tp3s First to third pulse width setting signal (width setting value) ID Welding current detection circuit Id Welding current detection signal CM3 Third comparison circuit Cm3 welding current energization signal

Claims (5)

[Claims] Claim 1: A first pulse current group with a small arc length;
In the pulsed MAG welding arc start control method, the pulsed MAG welding arc start control method includes periodically switching energization between the first pulsed current group and the second pulsed current group to make the arc length larger than the arc length caused by the energization of the first pulsed current group. - a third pulse current group having an average value between the average value of the pulse currents of the first pulse current group with a small arc length and the average value of the pulse currents of the second pulse current group with a large arc length; After energizing and starting the arc, the first and second
A pulsed MAG welding arc start control method in which a pulsed current group is periodically switched and energized. 2. A claim in which the third pulse current setting value of the third pulse current group is set between the first pulse current setting value of the first pulse current group and the second pulse current setting value of the second pulse current group. 2. The pulse MAG welding arc start control method according to item 1. 3. A claim in which the third pulse width setting value of the third pulse current group is set between the first pulse width setting value of the first pulse current group and the second pulse width setting value of the second pulse current group. Item 1
Pulse MAG welding arc start control method described in . 4. The pulse MAG according to claim 2, wherein the third pulse current setting value of the third pulse current group is calculated from a setting signal of the first pulse current setting value and a setting signal of the second pulse current setting value. Welding arc start control method. 5. The pulse MAG according to claim 3, wherein the third pulse width setting value of the third pulse current group is calculated from a setting signal of the first pulse width setting value and a setting signal of the second pulse width setting value. Welding arc start control method.