JP3533235B2 - Pulse MAG arc welding method and welding device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse MAG arc welding method and a welding apparatus for always obtaining a uniform back-bead in a back-side welding method such as a butt joint having a root gap.

[0002]

2. Description of the Related Art In recent years, aluminum and aluminum alloys (hereinafter referred to as "aluminum") have been widely used for interiors of building structures, vehicles, transportation equipment and the like. Since these welded joints form the outer surfaces of these structures as they are, it is needless to say that the welded joints require weld strength, but recently, it is required that the weld beads have a good appearance. It is like this.
Therefore, a TIG arc welding method in which a filler wire is added has been widely adopted as an arc welding method having a good weld bead appearance. This filler wire addition TIG-
When welded by a welding method (hereinafter referred to as TIG filler arc welding method), as shown in FIG. 1, a regular corrugated bead appearance (hereinafter referred to as "scaly bead") is obtained. It is more aesthetic than the welding beads of the MIG arc welding method.

Since the TIG arc welding method has a slower welding speed than the MIG arc welding method of melting the consumable electrode, the production efficiency is poor, so that the MIG having a high welding speed is used.
It has been proposed by the arc welding method to obtain a weld bead appearance close to the "scaly bead" in the filler wire-added TIG arc welding method and always obtain a uniform back bead.

(Prior Art 1) The prior art 1 is disclosed in Japanese Examined Patent Publication No. 46
The MIG arc welding method disclosed in Japanese Patent Application Laid-Open No. 650-650, which is a welding method in which the amount of arc spray is alternately changed between a high value and a low value, and in order to carry out the welding method, The power supplied to the arc is periodically switched between a relatively high value and a relatively low value (for example, 3: 2).

FIG. 2 is a block diagram of a welding power source used in the welding method, and FIG. 3 is an output current I of the welding power source.
It is a figure which shows the external output characteristic (henceforth an external characteristic) and arc characteristic of (horizontal axis) and output voltage V (vertical axis).
In FIG. 2, 101 is a welding power source output circuit,
Reference numeral 02 is a resistor for switching the external characteristics of the welding power supply output circuit 101, 103 is a contact for short-circuiting and opening the resistor 102, and 104 is a timer for periodically switching the contact 103. In addition, 1 is a wire feeding motor W
A consumable electrode wire (hereinafter, referred to as a consumable electrode) that is fed to the object to be welded 2 side through the power feeding tip 4 at a substantially constant speed determined by M. -Generate burrs 3 to perform welding.

FIG. 3 shows the external characteristic AA supplied to the consumable electrode 1 and the work piece 2 when the resistor 102 of FIG. 2 is connected to the output circuit, and the external characteristic AA when the resistor 102 is short-circuited. The external characteristics BB and the arc characteristics when the arc lengths L1 to L3 shown by the dotted lines L1 to L3 are shown. Now, the operating point when the consumable electrode 1 is fed at a predetermined constant wire feeding speed WF1 is the intersection A between the solid line AA and the dotted line L3 in FIG.
Suppose The welding current value at this time is I1, and
The voltage value is V1.

The following three methods are available for switching the above power.
There is one. The first is a method of switching the output voltage V supplied between the consumable electrode 1 and the workpiece 2. For example, in FIG.
In, when the characteristic curve AA of the external characteristic is switched to the characteristic curve BB, since the wire feeding speed WF1 is not changed, the welding current value I1 does not change, but the wire feeding speed and the welding current value are completely proportional. In order not to do so, it constantly moves to point B on the external characteristic curve BB. However, transiently, even if the external characteristic curve is suddenly switched to BB, the arc length L3 does not change rapidly, so the operating point is from point A to point D on the same arc characteristic curve L3. Since the welding current value increases due to the movement, the wire melting rate increases and the arc length becomes longer, and the arc length becomes the curve L.
It goes from 3 to the arc characteristic curve L2 having a long arc length, and finally moves to point B. Therefore, the welding current value transiently greatly changes from I1 to I3, and in a steady state I1
Changes from I2 to I2.

The second method is to switch the wire feeding speed. For example, in FIG. 3, when the wire feeding speed is switched, the operating point is switched from B to C because the arc length changes on the external characteristic curve BB. Therefore, the welding current value is largely switched from I2 to I4, and the arc length moves from the arc characteristic curve L2 to the operating point on L1.

A third method is to switch the above-mentioned external characteristic and the above-mentioned wire feeding speed at the same time. For example, in FIG. 3, the operating point switches from A to C. Therefore, the welding current value is largely switched from I1 to I4.

(Prior Art 2) The prior art 2 is disclosed in Japanese Examined Patent Publication No. 49
In the MAG welding method disclosed in Japanese Patent Laid-Open No. 48057, a consumable electrode is fed at a predetermined substantially constant speed by using a welding power source having a constant voltage characteristic. In the welding method of the prior art 2, the welding current is periodically changed and the welding wire feeding speed is changed to increase / decrease of the welding current. That is, it is a method of controlling heat input by periodically switching between a large current (high output voltage) at a high wire feeding speed and a small current (low output voltage) at a low wire feeding speed. 4A to 4C show the external characteristic curves AA and BB of the output current I (horizontal axis) and the output voltage V (vertical axis) of the welding power source, and FIG. Characteristic curve L
It is a figure which shows 1 and L2.

There are the following three specific methods for controlling the heat input. First, the first method is such that the arc length does not change at the time of large current and small current. For example, as shown in FIG. 4A, when both the external characteristic of the welding power source and the wire feeding speed are switched, the external characteristic curve AA and the arc characteristic curve L
The operating point A at the intersection with 1 moves to the operating point B at the intersection between the external characteristic curve BB and the arc characteristic curve L1. At this time, the welding current value changes greatly from I1 to I2.
The black length does not change at L1 on the same curve.

The second method is to increase or decrease the wire feeding speed more than when the arc length does not change,
When the current is large, the wire feeding speed is increased to shorten the arc length, and when the current is small, the wire feeding speed is reduced to increase the arc length. For example, as shown in FIG. 4B, when the wire feeding speed is switched, the operating point A at the intersection of the external characteristic curve AA and the arc characteristic curve L1 leads to the curve AA and the arc characteristic curve L2. Move to intersection B of. At this time, the welding current value greatly changes from I1 to I2 and the arc length changes from L1 to L2.

A third method is to increase or decrease the wire feeding speed to a small value by increasing or decreasing the wire feeding speed to a value smaller than that when the arc length does not change, and decreasing the wire feeding speed at a large current. When the current is high, the wire feeding speed is increased to shorten the arc length. For example, as shown in FIG. 4C, when both the external characteristics of the welding power source and the wire feeding speed are switched,
Normally, the operating point A at the intersection of the external characteristic curve AA and the arc characteristic curve L2 moves to the operating point B at the intersection of the external characteristic curve BB and the arc characteristic curve L1. However, excessively, even if the external characteristic curve suddenly switches to BB,
Since the arc length L2 does not change abruptly, the welding current value increases when moving on the same arc length L2 from point A to point D, so the wire melting rate increases and the arc length increases. , From the curve L2 having a long arc length to the curve L1 having a long arc length, and finally moves to the point B. Therefore, the welding current value transiently greatly changes from I1 to I3, and constantly changes from I1 to I2.

(Prior Art 3) The prior art 3 is disclosed in Japanese Patent Laid-Open No. Sho 62-62.
A pulse MIG welding method disclosed in Japanese Patent Publication No. 279087, wherein a "scaly bead" is formed by switching a base current or a base voltage between a spray transfer and a short-circuit transfer without causing burn through of an aluminum thin plate.
Is to form. 5 (A) and (B)
FIG. 4 is a waveform diagram of a welding current and a welding voltage according to the pulse MIG welding method. For example, as shown in the waveform diagram of the welding current in FIG. 5A, a welding current composed of a pulse current having a constant pulse current value, a pulse width and a pulse frequency, and a base current having a variable value is used. By using a pulse welding power source to output, by periodically changing the base current value,
Alternate spray and short circuit transitions occur. Moreover, as shown in the waveform diagram of the welding voltage in FIG.
Using a pulse welding power source that outputs a welding voltage consisting of a pulse voltage having a constant pulse voltage value, a pulse width, and a variable base voltage, all of which have a large base voltage value. By changing the distance, the spray transition and the short circuit transition are alternately performed.

Therefore, the prior art 3 is shown in FIG.
As shown in (A), by switching the wire feeding speed, the average value H1 of the welding current during the high current period T8 and the average value N1 of the welding current during the low current period T9 are changed,
The average value of the welding current is drastically changed periodically to change to the spray transition and the short circuit transition. Further, in the prior art 3, as shown in FIG. 5 (B), the output voltage of the base power supply is largely switched. The method of FIG. 5B is
Although the welding current value changes little in a steady state, the welding current value changes greatly in a transitional manner as in the case of the conventional technique 1.

[0018]

[Problems to be Solved by the Invention]

(Problem with Prior Art 1) The welding method of Prior Art 1 is
Since it is necessary to alternately switch the amount of arc spray between a high value and a low value at a critical current value Ic or more for spray transfer, the wire spray speed is also switched at the same time. The welding current value I2 for obtaining the quantity is considerably larger than the critical current value Ic. Therefore, the thin plate cannot be welded by the welding method of the conventional technique 1.

Further, in the welding method of the prior art 1, since the welding current value is changed relatively large (for example, 2: 3), the arc force is changed greatly, the penetration depth is changed, and the amount of deposited metal is changed. It is suitable for the purpose of changing the amount and shape of excess by increasing or decreasing. However, in the welding method of the prior art 1, while the penetration depth and the excess amount, which are the objectives of the welding method of the present invention described later, are kept substantially constant,
It is not suitable for the shape of the weld pool surface, for example "scaly beads" and for applications where a consistent backside bead is always obtained. Therefore, in the welding method of the prior art 1, the appearance of the weld bead as shown in FIG. 6 and the ripples such as the “scaly bead” of the TIG filler arc welding method shown in FIG. The regular aesthetic is not obtained. FIG. 6 is a view showing the appearance of a "scaly bead" produced by a conventional MIG arc welding method.

(Problem with Prior Art 2) In the welding method of Prior Art 2, the welding current value is greatly changed by periodically switching the output voltage of the welding power source having a constant voltage characteristic and the wire feeding speed (in the embodiment, in the embodiment). 260 [A] and 100 or 90 or 60 [A]) to control heat input.

Therefore, the welding method of the prior art 2 can control the heat input by largely changing the welding current value similarly to the prior art 1, so that the arc force is changed and the penetration depth is changed. It is suitable for applications such as changing the amount of deposited metal, preventing the bead from hanging, and changing the excess amount and its shape. However, in the welding method of the prior art 2, since it is difficult to rapidly change the wire feeding speed, the arc length is largely changed due to the response delay of the change in the wire feeding speed, and the arc is not stable, resulting in a uniform arc. Getting a good Uranami bead can be difficult.

(Problem with Prior Art 3) In the welding method of Prior Art 3, the pulse current value or the pulse voltage value and the pulse width and the pulse frequency are kept constant, and the base current or the base voltage is changed to the spray transfer and the short circuit transfer. It is intended to form a "scaly bead" without causing burn-through of the thin aluminum plate by changing the period to a large extent.

However, in the welding method of the prior art 3, since spray transfer and short-circuit transfer are periodically repeated, a welding method that does not cause burn-through or partial melt while maintaining the aesthetic appearance of the weld bead. Is difficult to do
The arc is not stable and it is difficult to obtain a uniform back bead.

[0030]

[Means for Solving the Problems]

(Claim 1) The welding method according to claim 1 is the first arc length L1.
In the pulse MAG arc welding method for periodically switching the first pulse current group PC1 for obtaining the second pulse current group PC2 and the second pulse current group PC2 for obtaining the second arc length L2 by the switching signal Hc, the consumable electrode 1 is fed with a predetermined wire. The period for supplying the pulse welding current of the first pulse current group PC1 and the period for supplying the pulse welding current of the second pulse current group PC2 are the second pulse energizing period. T2, the first arc length L1 and the second arc length L2 are different arc lengths L, and the second welding speed WS2 in the second pulse energization period T2 is 1 / the 1st welding speed WS1 in the first pulse energization period T1. A pulse M that is 2 or less or zero and that periodically switches the welding speed in synchronization with the switching signal Hc between the first pulse energization period T1 and the second pulse energization period T2.
This is an AG arc welding method.

(Claim 2) The welding method according to claim 2 is the second method.
The arc length L2 is smaller than the first arc length L1.
And the plate thickness of the object to be welded 2 exceeds 2 [mm].
The pulsed MAG arc welding method described in 1.

(Claim 3) The welding method according to claim 3 is the second method.
The arc length L2 is greater than the first arc length L1.
And the plate thickness of the object to be welded 2 is 2 [mm] or less.
The pulsed MAG arc welding method described in 1.

(Claim 4) The welding device according to claim 4 is the first
First pulse current group and second arc length L for obtaining arc length L1
In a pulse MAG arc welding apparatus that periodically switches the second pulse current group for obtaining 2 with a switching signal, an arc voltage detection circuit VD that detects an arc voltage value and outputs an arc voltage detection signal Vd, and an arc voltage setting signal. Vs
1 or a switching arc voltage signal S6 in which the first arc voltage setting signal Vs1 and the second arc voltage setting signal Vs2 are switched.
And an arc voltage detection signal Vd, and an arc voltage control circuit including a comparison circuit CM2 for outputting a difference arc voltage control signal Cm2, and a pulse frequency f3 or a pulse width corresponding to the arc voltage control signal Cm2. A pulse base current control circuit for outputting a pulse base current control signal for controlling TP3 or base current value IB3 or pulse current value IP3, and 4 of pulse current value and pulse width, pulse frequency and base current value of the first pulse current group. A first pulse base current setting circuit that outputs three first conditions except one controlled by the pulse base current control signal and outputs a first pulse base current setting signal; and a pulse current of the second pulse current group. Value, pulse width, pulse frequency, and base current value out of the four conditions, except for controlling with the pulse base current control signal A second pulse base current setting circuit that sets two conditions and outputs a second pulse base current setting signal, and a switching circuit HC that switches at a switching frequency F = 0.5 to 5 [Hz] and outputs a switching signal Hc. , The first arc voltage setting signal Vs1 and the second arc voltage setting signal Vs
2 is switched by the switching signal Hc to output the switching arc voltage signal S6, or the first pulse base current setting signal and the second pulse base current setting signal are switched by the switching signal Hc to output the switching setting signal. One or more switching setting circuits that output either or both signals, and a pulse control signal that inputs the pulse base current control signal and the switching setting signal and outputs the first pulse control signal Pf1 and the second pulse control signal Pf2. Generation circuit and first pulse control signal P
Welding power supply control circuit PS that outputs the first pulse current group when f1 is input and outputs the second pulse current group when the second pulse control signal Pf2 is input, and the switching signal Hc, and sets the synchronous output A synchronization signal output circuit SYO that outputs the signal Syo and a synchronization signal input circuit SYI that inputs the synchronization output setting signal Syo and outputs the synchronization input setting signal Syi
And the first welding speed setting signal Ws corresponding to the first welding speed
A first welding speed setting circuit WS1 which outputs 1 and a second welding speed setting circuit WS2 which outputs a second welding speed setting signal Ws2 corresponding to the second welding speed, a first welding speed setting signal Ws1 and a second welding Speed setting signal Ws2 and switching signal Hc
Pulse MAG equipped with a welding speed switching circuit SW11 for switching and outputting a switching welding speed setting signal S11
It is an arc welding device.

[0040]

Now, with reference to FIGS. 7 to 10, the second arc length L2 is set to an arc length L smaller than the first arc length L1,
The operation of the pulse MAG arc welding method of the present invention in which the plate thickness T of the work piece 2 exceeds 2 [mm] will be described.

(Explanation of FIG. 7) FIG. 7 shows the welding method of the present invention, in which the arc length L and the welding speed WS are changed when welding a butt joint having a root gap and having a plate thickness exceeding 2 [mm]. It is a figure which shows the appearance of a back bead and the penetration shape of a vertical cross section when it is made. FIG. 3A shows the power supply chip 4
It is a figure which shows the time course of the arc length L of the arc 3 which spreads between the consumable electrode 1 sent from
The first arc length L1 having a large arc length and the second arc length L2 having a small arc length are periodically switched. FIG.
FIG. 3 is a diagram showing a time course of a welding current I repeated by a first pulse current group PC1 for obtaining a first arc length L1 having a large arc length and a second pulse current group PC2 for obtaining a second arc length L2 having a small arc length. is there. In the same figure (B), the first pulse current group PC1 is composed of the first pulse current value IP1, the first pulse width TP1, the first base current IB1 and the first pulse energization period T1, and the second pulse current group PC2 is , Second pulse current value IP2, second pulse width TP1 which is the same as the first pulse width
, The same second base current IB1 as the first base current and the second pulse energization period T2. First pulse energization period T
1 and the second pulse energization period T2 are switched at a switching cycle (T1 + T2) by a switching signal Hc shown in FIG.

FIG. 7C is a view showing the welding speed WS over time, wherein the welding speed during the first pulse energization period T1 is the first welding speed WS1 and the welding speed during the second pulse energization period T2. Is less than the first welding speed WS1 or
The second welding speed WS2 is set to zero. Same figure (D)
[Fig. 3] is a diagram showing the appearance of the back bead, and Fig. 6 (E) is a diagram showing the penetration shape of the vertical cross section.

As shown in FIG. 7 (D), the object 2 to be welded can be broadly melted during the first pulse energization period T1 in which the arc length is large, and during this period T1, the same figure (C) is used. By moving the power feed tip 4 at the first welding speed WS1 shown in FIG. 1, the welding method for forming the back bead can be performed as shown in FIG. Next, by switching to the second arc length L2 having a small arc length, the period T
It is possible to suppress excessive heat input to the work piece 2 and prevent burn through. In the second pulse energization period T2 for generating the second arc length L2, as shown in FIG. 7C, at a second welding speed WS2 which is smaller than the first welding speed WS1 of the period T1 or is stopped. By performing welding, the heat input to the workpiece 2 does not become too small,
A reliable back bead can be formed as shown in FIG. By repeating the above operation, a butt joint having a root gap can be welded well.

(Explanation of FIG. 8) FIG. 8 shows that the work piece 2 is aluminum A5083, the welding method of the present invention shown by the solid line A and the conventional welding method shown by the dotted line Z are the thickness of the work piece 2 to be welded. T [mm] (horizontal axis) and root gap G [mm]
It is a figure which shows the result of whether a welding bead is good or not when (vertical axis) is changed. As shown in the figure, in the welding method of the present invention and the conventional welding method, the plate thickness T is 2 [mm].
Welding is not possible in the following cases. However, for example, the plate thickness T
Is 10 [mm], the conventional welding method can perform welding to form the back bead up to the root gap G of 4.5 [mm], whereas the welding method of the present invention uses 8
Welding can be done up to the root gap G of [mm],
The scope of application has been significantly expanded.

(Description of FIG. 9) FIG. 9 shows the pulse M of the present invention.
Second welding speed WS during the second pulse energization period T2 when welding a V-shaped groove butt joint by the AG arc welding method
It is a figure which shows a back bead result when changing 2 [cm / min] (horizontal axis) and root gap G [mm] (vertical axis). As the welding conditions, an aluminum-magnesium alloy A5083 having a plate thickness of 20 [mm] was used, an average welding current was 230 [A], and an average welding speed was 40 [cm / min].
Then, the first pulse current group PC1 and the second pulse current group PC2
And the switching frequency F = 1 [Hz], and the root gap G is changed from 1 [mm] to 8 [mm]. As shown in the figure, a pulse MAG forming a good back bead
In order to perform the arc welding method, the second welding speed WS2
However, 1/2 or less of the first welding speed WS1 or zero is suitable.

(Description of FIG. 10) FIG. 10 shows the second welding speed WS2 [cm / min] during the second pulse energization period T2 when the V-shaped groove butt joint is welded by the pulse MAG arc welding method of the present invention. (Horizontal axis) and first pulse current group PC
Switching frequency F [Hz] between 1 and the second pulse current group PC2
It is a figure which shows a back bead result when (vertical axis) is changed. As the welding conditions, an aluminum-magnesium alloy A5083 having a plate thickness of 10 [mm] was used, the root gap G of the butt joint was G = 2 [mm], and the average welding current was 2
At 30 [A], the average arc voltage is 23 [V], and the average welding speed is 40 [cm / min]. As shown in the figure,
When the switching frequency F is less than 0.5 [Hz], burn-through is likely to occur during the first pulse energization period T1, and when the switching frequency F exceeds 5 [Hz], heat input changes to the switching frequency F. It may not be able to follow and the back bead may not be formed. Therefore, in order to perform the pulse MAG arc welding method for forming a good back bead, the switching frequency F is 0.5.
The range from [Hz] to 5 [Hz] is suitable.

Hereinafter, referring to FIGS. 11 to 14, the second
The arc length L2 is larger than the first arc length L1.
Then, the operation of the pulse MAG arc welding method of the present invention in which the plate thickness T of the workpiece 2 is 2 [mm] or less will be described.

(Explanation of FIG. 11) FIG. 11 shows the welding method of the present invention, in which the arc length L and the welding speed WS are changed when welding a butt joint having a root gap and a plate thickness of 2 [mm] or less. It is a figure which shows the back bead appearance and the penetration shape of a vertical cross section when it is made. FIG. 1A is a diagram showing the time course of the arc length L of the arc 3 that spreads between the consumable electrode 1 fed from the power feeding tip 4 and the workpiece 2.
The first arc length L1 having a small arc length and the second arc length L2 having a large arc length are periodically switched. FIG.
FIG. 3 is a diagram showing a time course of a welding current I which is a repetition of a first pulse current group PC1 for obtaining a first arc length L1 with a small arc length and a second pulse current group PC2 for obtaining a second arc length L2 with a long arc length. is there. In the same figure (B), the first pulse current group PC1 is composed of the first pulse current value IP1, the first pulse width TP1, the first base current IB1 and the first pulse energization period T1, and the second pulse current group PC2 is , Second pulse current value IP2, second pulse width TP2 which is the same as the first pulse width
, The same second base current IB1 as the first base current and the second pulse energization period T2. First pulse energization period T
1 and the second pulse energization period T2 are switched at a switching cycle (T1 + T2) by a switching signal Hc shown in FIG. .

FIG. 11C is a diagram showing the welding speed WS over time. The welding speed in the first pulse energization period T1 is the first welding speed, and the welding speed in the second pulse energization period T2 is The second welding speed WS2 is smaller than the first welding speed WS1 or zero. FIG. 6D is a diagram showing the appearance of the back bead, and FIG. 6E is a diagram showing the penetration shape of the vertical cross section.

As shown in FIG. 11D, during the first pulse energization period T1 in which the arc length is small, the thin workpiece 2 is welded.
Can be melted while suppressing heat input without causing burn-through, and during this period T1, the first part shown in FIG.
By moving the power supply tip 4 at the welding speed WS1, a welding method for forming a back bead can be performed as shown in FIG. Next, by switching to the second arc length L2 having a large arc length, it is possible to prevent the heat input to the object to be welded 2 from becoming too small during the period T1 to cause poor melting. In the second pulse energization period T2 for generating the second arc length L2, as shown in FIG. 6C, at a second welding speed WS2 which is smaller than the first welding speed WS1 in the period T1 or is stopped. By performing welding, it is possible to replenish the heat input to the object to be welded 2 that has become insufficient and prevent the temperature from becoming excessively large, and to form a reliable back bead as shown in FIG. By repeating the above operation, it is possible to excellently weld a butt joint of a thin plate having a root gap and a plate thickness of 2 mm or less.

(Explanation of FIG. 12) FIG. 12 shows the plate thickness of the object to be welded 2 in the case where the object to be welded 2 is aluminum A5052, the welding method of the present invention shown by the solid line A and the conventional welding method shown by the dotted line Z. T [mm] (horizontal axis) and root gap G [m
It is a figure which shows the result of whether a welding bead is good or not when [m] (vertical axis) is changed. As shown in the figure, in the welding method of the present invention and the conventional welding method, the plate thickness T is 2
When [mm] is exceeded, welding is not possible. But for example,
When the plate thickness T is 1 [mm], the conventional welding method can perform welding to form the back bead up to the root gap G of 0.5 [mm]. On the other hand, in the welding method of the present invention, welding can be performed up to the root gap G of 3 [mm], and the applicable range is remarkably expanded.

(Explanation of FIG. 13) FIG. 13 shows the second welding speed WS2 [cm / min] during the second pulse energization period T2 when the I-shaped groove butt joint is welded by the pulse MAG arc welding method of the present invention. ] (Horizontal axis) and root gap G [m
It is a figure which shows a back bead result when [m] (vertical axis) is changed. As the welding conditions, an aluminum-magnesium alloy A5052 having a plate thickness of 2 [mm] was used, an average welding current was 80 [A], and an average welding speed was 50 [cm / min.
], The first pulse current group PC1 and the second pulse current group P
The switching frequency F with C2 is 1 [Hz], and the root gap G is changed from 0 [mm] to 5 [mm].
As shown in the figure, a pulse M that forms a good back bead
In order to perform the AG arc welding method, the second welding speed WS
It is suitable that 2 is less than 1/2 of the first welding speed WS1 or zero.

(Explanation of FIG. 14) FIG. 14 shows the second welding speed WS2 [cm / min] during the second pulse energization period T2 when the I-type groove butt joint is welded by the pulse MAG arc welding method of the present invention. ] (Horizontal axis) and first pulse current group P
Switching frequency F [H between C1 and second pulse current group PC2
It is a figure which shows a back bead result at the time of changing z] (vertical axis). As the welding conditions, an aluminum / magnesium alloy A5052 having a plate thickness of 2 [mm] was used, the root gap of the butt joint was G = 2 [mm], the average welding current was 80 [A], and the average arc voltage was 18 [ V], the average welding speed is 50 [cm / min]. As shown in the figure,
When the switching frequency F is less than 0.5 [Hz], whether the back bead is not formed due to poor melting during the first pulse energization period T1 or the meltdown occurs during the second pulse energization period T2. Either phenomenon is likely to occur. Further, when the switching frequency F exceeds 5 [Hz], the change in heat input cannot follow the switching frequency F, and the back bead may not be formed uniformly. Therefore, in order to perform the pulse MAG arc welding method for forming a good back bead, the switching frequency F is 0.5 [Hz] or more and 5 [H] or more.
The following range is suitable.

[0060]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 15 to 30 show the pulse MAG of the present invention.
It is a block diagram of the Example of the welding apparatus which implements an arc welding method. In the pulse MAG arc welding method of the present invention according to claim 1, the welding currents of the first pulse current group for obtaining the first arc length L1 and the second pulse current group for obtaining the second arc length L2 are defined as the first arc length L1. And the second arc length L2 are set to be different arc lengths L. In the pulse MAG arc welding method of the present invention according to claim 2, the welding current of the first pulse current group and the second pulse current group is set to an arc length L in which the second arc length L2 is smaller than the first arc length L1. To be set. In the pulse MAG arc welding method of the present invention according to claim 3, the welding currents of the first pulse current group and the second pulse current group are calculated so that the second arc length L2 is the first arc length L.
Set so that the arc length L is greater than 1.

(Explanation of FIG. 15) FIG. 15 is a block diagram of a first embodiment of a welding apparatus for carrying out the pulsed MAG arc welding method of the present invention.

In the figure, the commercial power supply AC is used as an input to supply an output from the welding power supply control circuit PS between the power supply tip 4 of the consumable electrode 1 and the object to be welded 2 to generate the arc 3. The consumable electrode 1 is supplied from a wire feeding roller WR rotated by a wire feeding motor WM. The wire feeding speed control circuit WC outputs the average current setting signal Im output from the average current setting circuit IM and the feeding speed detection signal Wd of the wire feeding speed detection circuit WD that detects the rotation speed of the wire feeding motor WM. A wire feed speed control signal Cm1 of a wire feed speed comparison circuit (hereinafter referred to as a first comparison circuit) CM1 to be compared is input, and a wire feed speed control signal Wc is output to a wire feed motor WM. The arc voltage setting circuit VS1 is a circuit for setting the arc voltage and outputs the arc voltage setting signal Vs1. Second comparison circuit CM2
Is the arc voltage setting signal Vs1 and the arc voltage detection circuit V
The arc voltage detection signal Vd of D is input and the arc voltage control signal Cm2 of the difference is output. The energization frequency setting circuit FT is a circuit for setting the switching frequency F of the switching signal Hc for switching between the first pulse energization period T1 and the second pulse energization period T2, and the setting of 0.5 to 5 Hz is appropriate, The energization frequency signal Ft is output. Since the welding speed WS and the switching frequency F for obtaining an appropriate welding result have a large relationship, the welding speed setting signal W of the welding speed setting circuit WS is set.
s is input to the energization frequency setting circuit FT, and the energization frequency signal Ft corresponding to the welding speed is input to the switching signal generation circuit HC. The energization ratio setting circuit DT is a circuit for setting the ratio between the second pulse energization period T2 of the second welding condition and the first pulse energization period T1 of the first welding condition, and the energization ratio signal Dt.
Is output. The switching signal generation circuit HC inputs a signal Ft and a signal Dt and periodically switches between a first pulse energization period T1 and a second pulse energization period T2.
Output c. The first pulse current value setting circuit IP1 and the second pulse current value setting circuit IP2 respectively have a first pulse current value setting signal Ip1 and a second pulse current value setting signal Ip.
Output p2. The pulse current value switching circuit SW1 switches between the signals Ip1 and Ip2 by the switching signal Hc and outputs the switching pulse current value signal S1.

The pulse frequency control signal generation circuit VF3 is
A pulse frequency control signal Vf3 is output corresponding to the arc voltage control signal Cm2. The pulse width setting circuit TP1 is
The pulse width setting signal Tp1 is output. The pulse width frequency control signal generation circuit DF3 outputs a pulse width frequency control signal Df3 including a pulse width setting signal Tp1 and a pulse frequency control signal Vf3. Base current setting circuit IB1
Outputs the base current setting signal Ib1. Under the first welding condition, the pulse base current switching circuit SW5 outputs the first pulse current value setting signal Ip1 and the base current setting signal Ib1 of the first welding condition to the pulse width frequency control signal Df.
Switch by 3 to output the pulse control signal Pf1,
Next, in the second welding condition, the signal Ip of the second welding condition
2 and the signal Ib1 are switched by the pulse width frequency control signal Df3 to output the pulse control signal Pf2, which is input to the welding power source control circuit PS.

The synchronization signal output circuit SYO receives a switching signal Hc for periodically switching between the first pulse energization period T1 and the second pulse energization period T2, and outputs the synchronization output setting signal Syo.
Is output. The synchronization signal input circuit SYI provided in the welding robot or the automatic traveling vehicle AT receives the synchronization output setting signal Syo and outputs the synchronization input setting signal Syi. The first welding speed setting circuit WS1 outputs the first welding speed setting signal Ws1 corresponding to the first welding speed, and the second welding speed setting circuit WS2 corresponds to the second welding speed or the first welding. The second welding speed setting signal Ws2 is output after being converted into a predetermined value corresponding to the speed setting signal Ws1. The welding speed switching circuit SW11 outputs the first welding speed setting signal Ws1 in the first pulse energization period T1 according to the synchronous input setting signal Syi synchronized with the switching signal Hc, or
During the second pulse energization period T2, the second welding speed setting signal Ws2
Is output as a switching welding speed signal S11. This switching welding speed signal S11 is used for the welding robot or the automatic traveling carriage A.
A pulse MAG arc welding method that always obtains uniform back bead can be performed in back bead welding such as a butt joint having a root gap input to T.

(Explanation of FIG. 16) FIG. 16 is a block diagram of a second embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 15 is omitted, and a different configuration will be described. The first pulse width setting circuit TP1 and the second pulse width setting circuit TP2 output a first pulse width setting signal Tp1 and a second pulse width setting signal Tp2, respectively. The pulse width switching circuit SW2 is
The switching signal Hc switches the signals Tp1 and Tp2 to output a switching pulse width signal S2. The pulse frequency control signal generation circuit VF3 outputs a pulse frequency control signal Vf3 corresponding to the arc voltage control signal Cm2. The pulse width frequency control signal generation circuit DF3 includes a first pulse width frequency control signal Df corresponding to a first welding condition including a first pulse width setting signal Tp1 and a pulse frequency control signal Vf3.
31 and a second pulse width frequency control signal Df32 corresponding to the second welding condition consisting of the second pulse width setting signal Tp2 and the pulse frequency control signal Vf3. Under the first welding condition, the pulse base current switching circuit SW5 switches the pulse current value setting signal Ip1 and the base current setting signal Ib1 by the first pulse width frequency control signal Df31 and outputs the pulse control signal Pf1. In the second welding condition, the signal Ip1 and the signal Ib1 are switched by the second pulse width frequency control signal Df32 to output the pulse control signal Pf2, which is input to the welding power source control circuit PS.

(Explanation of FIG. 17) FIG. 17 is a block diagram of a third embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 15 is omitted, and a different configuration will be described. The first base current setting circuit IB1 and the second base current setting circuit IB2 output a first base current setting signal Ib1 and a second base current setting signal Ib2, respectively. Base current switching circuit S
W3 is a signal Ib1 and a signal Ib2 depending on the switching signal Hc.
And the switching base current signal S3 is output. The pulse frequency control signal generation circuit VF3 outputs a pulse frequency control signal Vf3 corresponding to the arc voltage control signal Cm2. The pulse width frequency control signal generation circuit DF3 outputs a pulse width frequency control signal Df3 including a pulse width setting signal Tp1 and a pulse frequency control signal Vf3. The pulse base current switching circuit SW5 switches between the pulse current value setting signal Ip1 and the signal Ib1 of the first welding condition of the switching base current signal S3 by the pulse width frequency control signal Df3, and outputs the pulse control signal Pf1. Signal I
The pulse width frequency control signal Df3 is used to switch between p1 and the signal Ib2 of the second welding condition of the signal S3 to output the pulse control signal Pf2, which is input to the welding power source control circuit PS.

(Explanation of FIG. 18) FIG. 18 is a block diagram of a fourth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 15 is omitted, and a different configuration will be described. First pulse current value setting circuit IP1 and second pulse current value setting circuit IP
2 outputs a first pulse current value setting signal Ip1 and a second pulse current value setting signal Ip2, respectively. The first pulse width setting circuit TP1 and the second pulse width setting circuit TP2 are
It outputs the first pulse width setting signal Tp1 and the second pulse width setting signal Tp2, respectively. Pulse current value switching circuit SW
1 outputs the switching pulse current value signal S1 by switching the signals Ip1 and Ip2 by the switching signal Hc. The pulse width switching circuit SW2 switches between the signals Tp1 and Tp2 according to the switching signal Hc and outputs the switching pulse width signal S2.
The pulse frequency control signal generation circuit VF3 corresponds to the arc voltage control signal Cm2 and corresponds to the pulse frequency control signal Vf3.
Is output. Pulse width frequency control signal generator DF3
Is a pulse width frequency control signal Df31 corresponding to the first welding condition consisting of a first pulse width setting signal Tp1 and a pulse frequency control signal Vf3, and a second pulse width setting signal Tp2 and a pulse frequency control signal Vf3. The second pulse width frequency control signal Df32 corresponding to the two welding conditions is output. In the first welding condition, the pulse base current switching circuit SW5 switches between the pulse current value setting signal Ip1 and the base current setting signal Ib1 of the first welding condition of the signal S1 by the first pulse width frequency control signal Df31 to pulse. The control signal Pf1 is output, and then, under the second welding condition, the signal Ip2 and the signal Ib1 of the second welding condition of the signal S1.
Are switched by the second pulse width frequency control signal Df32 to output the pulse control signal Pf2, which is input to the welding power source control circuit PS.

(Explanation of FIG. 19) FIG. 19 is a block diagram of a fifth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 15 is omitted, and a different configuration will be described. First pulse current value setting circuit IP1 and second pulse current value setting circuit IP
2 outputs the first pulse current value setting signal Ip1 and the second pulse current value setting signal Ip2, respectively, and the first pulse width setting circuit TP1 and the second pulse width setting circuit TP2 respectively output the first pulse width setting signal Tp1. And a second pulse width setting signal Tp2. First base current setting circuit IB
The first and second base current setting circuits IB2 are respectively provided with a first base current setting signal Ib1 and a second base current setting signal Ib.
b2 is output. The pulse current value switching circuit SW1 switches the signals Ip1 and Ip2 by the switching signal Hc and outputs the switching pulse current value signal S1. Pulse width switching circuit S
W2 switches signals Tp1 and Tp2 by switching signal Hc and outputs switching pulse width signal S2. The base current switching circuit SW3 switches between the signal Ib1 and the signal Ib2 according to the switching signal Hc and outputs the switching base current signal S3. The pulse frequency control signal generation circuit VF3 outputs a pulse frequency control signal Vf3 corresponding to the arc voltage control signal Cm2. Pulse width frequency control signal generator D
F3 is a pulse width frequency control signal Df31 corresponding to the first welding condition consisting of the first pulse width setting signal Tp1 and the pulse frequency control signal Vf3, and a second pulse width setting signal Tp.
A pulse width frequency control signal Df32 corresponding to the second welding condition consisting of 2 and the pulse frequency control signal Vf3 is output. The pulse base current switching circuit SW5 has a pulse current value setting signal Ip1 for the first welding condition of the signals S13 and S3.
And the base current setting signal Ib1 are switched by the first pulse width frequency control signal Df31 to switch the pulse control signal Pf.
1 is output, and then the signal Ip2 and the signal Ib2 of the second welding condition of the signal S1 and the signal S3 are switched by the second pulse width frequency control signal Df32 to change the pulse control signal Pf2.
To the welding power source control circuit PS.

(Explanation of FIG. 20) FIG. 20 is a block diagram of a sixth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 15 is omitted, and a different configuration will be described. First arc voltage setting circuit VS1 and second arc voltage setting circuit VS2
Is a circuit for setting the arc voltage under the first welding condition and the arc voltage under the second welding condition, respectively, and outputs the first arc voltage setting signal Vs1 and the second arc voltage setting signal Vs2. Arc voltage switching circuit SW
Reference numeral 6 switches the signals Vs1 and Vs2 by the switching signal Hc and outputs a switching arc voltage signal S6. The second comparison circuit CM2 inputs the signal S6 and the arc voltage detection signal Vd of the arc voltage detection circuit VD and outputs an arc voltage control signal Cm2 of the difference.

The pulse frequency control signal generation circuit VF3 is
In response to the arc voltage control signal Cm2, the first pulse frequency control signal Vf31 under the first welding condition and the second pulse frequency control signal Vf32 under the second welding condition are switched at the switching frequency F of the switching signal Hc. Output. The pulse width frequency control signal generation circuit DF3 includes the first pulse width frequency control signal Df31 corresponding to the first welding condition including the first pulse width setting signal Tp1 and the first pulse frequency control signal Vf31, as well as the second pulse width frequency control signal Df31. And a second pulse width frequency control signal Df32 corresponding to the welding condition No. Under the first welding condition, the pulse base current switching circuit SW5 has a pulse current value setting signal Ip1 and a base current setting signal Ib1.
Are switched by the first pulse width frequency control signal Df31 to output the pulse control signal Pf1, and then, under the second welding condition, the signal Ip1 and the signal Ip of the second welding condition.
b1 is switched by the second pulse width frequency control signal Df32 to output the pulse control signal Pf2, which is input to the welding power source control circuit PS.

(Explanation of FIG. 21) FIG. 21 is a block diagram of a seventh embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 19 is omitted, and a different configuration will be described. In FIG. 21, a first configuration different from FIG. 19 includes a first arc voltage setting circuit VS1 and a second arc voltage setting circuit VS2 instead of the arc voltage setting circuit VS1.
A circuit for setting an average value of each arc voltage in the pulse energization period T1 and the second pulse energization period T2,
The arc voltage setting signal Vs1 and the second arc voltage setting signal Vs2 are output. The arc voltage switching circuit SW6 switches between the signal Vs1 and the signal Vs2 by the switching signal Hc and outputs a switching arc voltage signal S6. Second comparison circuit C
The M2 receives the signal S1 and the arc voltage detection signal Vd of the arc voltage detection circuit VD as inputs, and outputs an arc voltage control signal Cm2 of the difference. The pulse frequency control signal generation circuit VF3 corresponds to the arc voltage control signal Cm2,
The first pulse frequency control signal Vf31 under the welding condition and the second pulse frequency control signal Vf32 under the second welding condition are switched at the switching frequency F of the switching signal Hc and output.
The pulse width frequency control signal generation circuit DF3 includes a first pulse width frequency control signal Df31 corresponding to a first welding condition including a first pulse width setting signal Tp1 and a pulse frequency control signal Vf31, and a second pulse width setting signal Tp2. And a second pulse width frequency control signal Df32 corresponding to the second welding condition consisting of the pulse frequency control signal Vf32 and the pulse frequency control signal Vf32. The pulse-based current switching circuit SW5 has signals S1 and S3.
The pulse current value setting signal Ip1 and the base current setting signal Ib1 of the first welding condition are switched by the first pulse width frequency control signal Df31 to output the pulse control signal Pf1, and then the second of the signals S1 and S3. Welding condition signal I
p2 and the signal Ib2 together with the second pulse width frequency control signal D
The pulse control signal Pf2 is output by switching according to f32 and input to the welding power source control circuit PS.

In FIG. 21, a second configuration different from that of FIG. 19 is that instead of the average current setting circuit IM of FIG. 19, a first welding current setting circuit IM1 that outputs a first welding current setting signal Im1 and a second welding current setting circuit IM1. Second output current setting signal Im2
Welding current setting circuit IM2 and first welding current setting signal Im
There is provided a wire feeding speed switching circuit SW7 for switching between 1 and the second welding current setting signal Im2 by the switching signal Hc and inputting the switching wire feeding speed signal S7 to the first comparing circuit CM1. Except for the above, the configuration is the same as that of FIG. 19, so description thereof will be omitted.

(Explanation of FIG. 22) FIG. 22 is a block diagram of an eighth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 15 is omitted, and a different configuration will be described. First pulse current value setting circuit IP1 and second pulse current value setting circuit IP
Reference numeral 2 denotes a circuit for setting the first pulse current value IP1 and the second pulse current value IP2, respectively, which includes a first pulse current value setting signal Ip1 and a second pulse current value setting signal Ip.
Outputs 2. The pulse current value switching circuit SW1 switches between the signal Ip1 and the signal Ip2 by the switching signal Hc and outputs the switching pulse current value signal S1. First pulse frequency setting circuit FP1 and second pulse frequency setting circuit FP2
Is a circuit for setting the first pulse frequency f1 and the second pulse frequency f2, respectively, and outputs the first pulse frequency setting signal Fp1 and the second pulse frequency setting signal Fp2. The pulse frequency switching circuit SW4 has a switching signal Hc.
To switch the signal Fp1 and the signal Fp2 to output the switching pulse frequency signal S4. The pulse frequency signal generation circuit VF receives the switching pulse frequency signal S4 as a first signal.
Pulse frequency signal Vf1 and second pulse frequency signal Vf
Outputs 2. Pulse width frequency control signal generator DF3
Is the first pulse width control signal and the first pulse frequency signal Vf
A first pulse width frequency control signal Df31 corresponding to 1 and
The second pulse width control signal Df32 corresponding to the second pulse width control signal and the second pulse frequency signal Vf2 is output. In the first pulse energization period T1, the pulse base current switching circuit SW5 has the first pulse current value setting signal Ip1 for a period corresponding to the pulse width determined by the pulse width control signal combined with the first pulse width frequency control signal Df31. And the first base current setting signal Ib1 are switched by the first pulse width frequency control signal Df31 to output the pulse control signal Pf1. Next, in the second pulse energization period T2, the second pulse width Frequency control signal Df32
The second pulse current value setting signal Ip2 for a period corresponding to the second pulse width determined by the second pulse width control signal
Signal for energizing the second base current setting signal Ib2,
The pulse control signal Pf2 is switched to the second pulse width frequency control signal Df32 and input to the welding power source control circuit PS.

(Explanation of FIG. 23) FIG. 23 is a block diagram of a ninth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 22 is omitted, and a different configuration will be described. First arc voltage setting circuit VS1 and second arc voltage setting circuit VS2
Is a circuit for setting the average value of the arc voltage in the first pulse energization period T1 and the second pulse energization period T2, respectively, and outputs the first arc voltage setting signal Vs1 and the second arc voltage setting signal Vs2. The arc voltage switching circuit SW6 switches between the signal Vs1 and the signal Vs2 by the switching signal Hc and outputs a switching arc voltage signal S6. The second comparison circuit CM2 inputs the signal S6 and the arc voltage detection signal Vd of the arc voltage detection circuit VD and outputs an arc voltage control signal Cm2 of the difference. The pulse frequency setting circuit FP1 outputs a pulse frequency setting signal Fp1 corresponding to the pulse cycle (D1 = D2). The pulse frequency signal generation circuit VF has a pulse frequency setting signal Fp1.
To generate a pulse frequency signal Vf1. The pulse width frequency control signal generation circuit DF3 is composed of, for example, a comparison circuit, and controls the pulse width corresponding to the first arc voltage setting signal Vs1 by the first arc voltage control signal Cm2.
And a pulse frequency signal Vf1, a first pulse width frequency control signal Df31, a second arc voltage control signal Cm2 for controlling the pulse width corresponding to the second arc voltage setting signal Vs2, and a pulse frequency signal Vf1. It outputs the 2-pulse width frequency control signal Df32. In the first pulse energization period T1, the pulse base current switching circuit SW5 energizes the pulse current value setting signal Ip1 for a period corresponding to the pulse width determined by the pulse width control signal combined with the first pulse width frequency control signal Df31. Signal and the first base current setting signal Ib1 are switched by the first pulse width frequency control signal Df31 to output the pulse control signal Pf1, and then in the second pulse energization period T2, the second pulse width frequency control is performed. A signal for energizing the pulse current value setting signal Ip1 and a second base current setting signal Ib2 for a period corresponding to the pulse width determined by the pulse width control signal combined with the signal Df32 are switched by the second pulse width frequency control signal Df32. To input the pulse control signal Pf2 to the welding power source control circuit PS.

(Explanation of FIG. 24) FIG. 24 is a block diagram of a tenth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 22 is omitted, and a different configuration will be described. In FIG. 24, a first configuration different from that of FIG. 22 includes a first arc voltage setting circuit VS1 and a second arc voltage setting circuit VS2 instead of the arc voltage setting circuit VS1, and each has a first arc voltage setting circuit VS1.
A circuit for setting an average value of each arc voltage in the pulse energization period T1 and the second pulse energization period T2,
The arc voltage setting signal Vs1 and the second arc voltage setting signal Vs2 are output. The arc voltage switching circuit SW6 switches between the signal Vs1 and the signal Vs2 by the switching signal Hc and outputs a switching arc voltage signal S6. Second comparison circuit C
The M2 receives the signal S1 and the arc voltage detection signal Vd of the arc voltage detection circuit VD as inputs, and outputs an arc voltage control signal Cm2 of the difference. Pulse frequency signal generator VF
Inputs the switching pulse frequency signal S4 and outputs the first pulse frequency signal Vf1 and the second pulse frequency signal Vf2. The pulse width frequency control signal generation circuit DF3 has a first
A first pulse width frequency control signal Df31 corresponding to the pulse width control signal and the first pulse frequency setting signal Fp1;
The second pulse width frequency control signal Df32 corresponding to the pulse width control signal and the second pulse frequency setting signal Fp2 is output. In the first pulse energization period T1, the pulse base current switching circuit SW5 sets the first pulse current value for a period corresponding to the pulse width determined by the first pulse width control signal combined with the first pulse width frequency control signal Df31. Signal Ip
The signal for energizing 1 and the first base current setting signal Ib1 are switched by the first pulse width frequency control signal Df31 to output the pulse control signal Pf1, and then the second pulse is applied in the second pulse energization period T2. The second determined by the second pulse width control signal combined with the width frequency control signal Df32.
A signal for energizing the second pulse current value setting signal Ip2 and a second base current setting signal Ib2 for a period corresponding to the pulse width.
Are switched by the second pulse width frequency control signal Df32 to input the pulse control signal Pf2 to the welding power source control circuit PS.

(Description of FIG. 25) FIG. 25 is a block diagram of an eleventh embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 15 is omitted, and a different configuration will be described. The apparatus of this embodiment is provided with a base current control circuit IB3, and the first pulse energization period is changed by the switching signal Hc of the switching signal generation circuit HC which switches between the first pulse energization period T1 and the second pulse energization period T2. At T1, the first pulse voltage control signal Cm2 is controlled when the preset pulse current value, pulse width, pulse period and arc length are small.
The first pulse current group determined by the base current value is energized, and during the second pulse energization period T2, the second pulse current value, the pulse width, the pulse period and the second pulse value when the arc length is large are determined. A second pulse current group defined by a second base current value controlled by the arc voltage control signal Cm2 is energized. Further, the set values of the first pulse current group and the second pulse current group are the same as those of the first pulse current value IB31 of the first pulse energization period T1 when a plurality of pulses having a short arc length are transferred to a single droplet. The value for forming one pulse / one droplet transfer is used, and the second base current value IB32 in the second pulse energization period T2 is set to one pulse / one droplet transfer or one pulse multiple droplet transfer having a long arc length. The first pulse energization period T is changed within the range to be formed.
The arc length of 1 and the arc length of the second pulse energization period T2 are changed.

First pulse current value setting circuit IP1 and second
The pulse current value setting circuit IP2 is a circuit for setting the first pulse current value IP1 and the second pulse current value IP2, respectively, and includes a first pulse current value setting signal Ip1 and a second pulse current value setting signal Ip1.
The pulse current value setting signal Ip2 is output. The pulse current value switching circuit SW1 receives the signal Ip1 according to the switching signal Hc.
And the signal Ip2 are switched to output the switching pulse current value signal S1.

The first pulse width setting circuit TP1 and the second pulse width setting circuit TP2 respectively have a first pulse width TP1.
And a circuit for setting the second pulse width TP2,
Pulse width setting signal Tp1 and second pulse width setting signal Tp
Outputs 2. The pulse width switching circuit SW2 has a switching signal Hc.
Thus, the signal Tp1 and the signal Tp2 are switched to output the switching pulse width signal S2.

First pulse frequency setting circuit FP1 and second
The pulse frequency setting circuit FP2 is a circuit for setting the first pulse frequency f1 and the second pulse frequency f2, respectively, and outputs the first pulse frequency setting signal Fp1 and the second pulse frequency setting signal Fp2. The pulse frequency switching circuit SW4 switches between the signal Fp1 and the signal Fp2 by the switching signal Hc and outputs the switching pulse frequency signal S4.

The pulse frequency signal generation circuit VF inputs the switching pulse frequency signal S4 and receives the first pulse frequency signal V4.
f1 and the second pulse frequency signal Vf2 are output. The pulse width frequency signal generating circuit DF includes a first pulse width frequency signal Df1 corresponding to the first pulse width setting signal Tp1 and the first pulse frequency setting signal Fp1, a second pulse width setting signal Tp2 and a second pulse frequency setting signal. The second pulse width frequency signal Df2 corresponding to the signal Fp2 is output. During the first pulse energization period, the pulse-based current switching circuit SW5 has the first pulse current value setting signal Ip1 for a period corresponding to the pulse width determined by the pulse width setting signal Tp1 combined with the first pulse width frequency signal Df1. The pulse control signal Pf1 by switching the signal for energizing the first base current control signal Ib31 and the first pulse width frequency signal Df1.
In the second pulse energization period
A signal for energizing the second pulse current value setting signal Ip2 for a period corresponding to the second pulse width determined by the second pulse width setting signal Tp2 combined with the pulse width frequency signal Df2 and the second signal.
The base current control signal Ib32 is switched by the second pulse width frequency signal Df2 to input the pulse control signal Pf2 to the welding power source control circuit PS.

(Explanation of FIG. 26) FIG. 26 is a block diagram of a twelfth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 25 is omitted, and a different configuration will be described. In FIG. 26, the first arc voltage setting circuit VS1 and the second arc voltage setting circuit VS2 respectively have a first pulse energization period T1.
And a circuit for setting the average value of each arc voltage in the second pulse energization period T2, which outputs the first arc voltage setting signal Vs1 and the second arc voltage setting signal Vs2.
The arc voltage switching circuit SW6 receives the switching signal Hc,
A switching arc voltage signal S6 is output by switching between the signal Vs1 and the signal Vs2. The second comparator circuit CM2 receives the signal S6 and the arc voltage detection signal Vd of the arc voltage detection circuit VD as inputs, and outputs an arc voltage control signal Cm2 of the difference. The base current control circuit IB3 has a first arc voltage control signal Cm2 and a second arc voltage control signal Cm2 in the first pulse energization period T1.
The second arc voltage control signal Cm2 in the pulse energization period T2 is input to each of the first base current values IB31.
And a first base current control signal Ib31 and a second base current control signal Ib32 corresponding to the second base current value IB32.

The pulse current value setting circuit IP1 is a circuit for setting a pulse current value, and is a pulse current value setting signal I
Output p1. The pulse frequency setting circuit FP1 outputs a pulse frequency setting signal Fp1 corresponding to the pulse cycle (D1 = D2). The pulse width setting circuit TP1 is a circuit for setting the pulse width and outputs the pulse width setting signal Tp1. The pulse frequency signal generation circuit VF receives the pulse frequency setting signal Fp1 as an input and outputs the pulse frequency signal Vf.
Raises 1. The pulse width frequency signal generation circuit DF outputs a pulse width frequency signal Df1 composed of the pulse width setting signal Tp1 and the pulse frequency signal Vf1. Pulse base
In the first pulse energization period T1, the switch current switching circuit SW5 has a signal for energizing the pulse current value setting signal Ip1 for a period corresponding to the pulse width determined by the pulse width setting signal combined with the pulse width frequency signal Df1. The 1-base current control signal Ib31 is switched by the pulse width frequency signal Df1 to output the pulse control signal Pf1, and then, in the second pulse energization period T2, the pulse width synthesized into the pulse width frequency signal Df1. The pulse current control signal Pf2 is switched by the pulse width frequency signal Df1 between the signal for supplying the pulse current value setting signal Ip1 and the second base current control signal Ib32 for a period corresponding to the pulse width determined by the setting signal. Input to the circuit PS.

(Explanation of FIG. 27) FIG. 27 is a block diagram of a thirteenth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 25 is omitted, and a different configuration will be described. 27, the first configuration different from that of FIG. 25 is that the first arc voltage setting circuit V1 is replaced with the first arc voltage setting circuit V1 of FIG.
S1 and a second arc voltage setting circuit VS2 are provided,
A circuit for setting the average value of the respective arc voltages during the first pulse energization period T1 and the second pulse energization period T2, respectively, which includes a first arc voltage setting signal Vs1 and a second arc voltage setting signal Vs1.
It outputs the voltage setting signal Vs2. The arc voltage switching circuit SW6 outputs the signal Vs1 and the signal Vs according to the switching signal Hc.
s2 is switched to output a switching arc voltage signal S6.
The second comparator circuit CM2 inputs the signal S1 and the arc voltage detection signal Vd of the arc voltage detection circuit VD and outputs an arc voltage control signal Cm2 of the difference. The base current control circuit IB3 includes a first arc voltage control signal Cm2 and a second pulse energization period T2 in the first pulse energization period T1.
At the second arc voltage control signal Cm2 as an input, the first base current control signal Ib31 and the second base current control signal Ib31 corresponding to the first base current value IB31 and the second base current value IB32, respectively. The current control signal Ib32 is input.

In FIG. 27, a second configuration different from FIG. 25 is that instead of the average current setting circuit IM of FIG. 25, a first welding current setting circuit IM1 for outputting a first welding current setting signal Im1 and a second welding current Second output current setting signal Im2
Welding current setting circuit IM2 and first welding current setting signal Im
There is provided a wire feeding speed switching circuit SW7 for switching between 1 and the second welding current setting signal Im2 by the switching signal Hc and inputting the switching wire feeding speed signal S7 to the first comparing circuit CM1. Other than the above, the configuration is the same as that of FIG.

(Explanation of FIG. 28) FIG. 28 is a block diagram of a fourteenth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 15 is omitted, and a different configuration will be described. The configuration in FIG. 28 different from that in FIG. 15 is as follows. First pulse width setting circuit TP1 and second pulse width setting circuit TP2
Are the first pulse width TP1 and the second pulse width T, respectively.
A circuit for setting P2, the first pulse width setting signal T
p1 and the second pulse width setting signal Tp2 are output. The pulse width switching circuit SW2 receives the signal Tp according to the switching signal Hc.
The switching pulse width signal S2 is output by switching between 1 and the signal Tp2.

The first pulse frequency setting circuit FP1 and the second
The pulse frequency setting circuit FP2 is a circuit for setting the first pulse frequency f1 and the second pulse frequency f2, respectively, and outputs the first pulse frequency setting signal Fp1 and the second pulse frequency setting signal Fp2. The pulse frequency switching circuit SW4 switches between the signal Fp1 and the signal Fp2 by the switching signal Hc and outputs the switching pulse frequency signal S4.

The first base current setting circuit IB1 and the second base current setting circuit IB2 are circuits for setting the first base current IB1 and the second base current IB2, respectively. It outputs the first base current setting signal Ib1 and the second base current setting signal Ib2. Base current switching circuit SW3
Outputs the switching base current signal S3 by switching between the signals Ib1 and Ib2 by the switching signal Hc.

The pulse frequency signal generation circuit VF inputs the switching pulse frequency signal S4 and receives the first pulse frequency signal V4.
f1 and the second pulse frequency signal Vf2 are output. The pulse width frequency signal generation circuit DF has a first pulse width setting signal Tp1 and a first pulse frequency signal Vf1 corresponding to the first pulse width setting signal Tp1.
The pulse width frequency signal Df1 and the second pulse width setting signal T
The second pulse width frequency signal Df2 corresponding to p2 and the second pulse frequency signal Vf2 is output. During the first pulse energization period T1, the pulse-based current switching circuit SW5 outputs the first pulse current value control signal for a period corresponding to the pulse width determined by the pulse width setting signal Tp1 combined with the first pulse width frequency signal Df1. Signal to energize Ip31 and first
The base current setting signal Ib1 is switched by the first pulse width frequency signal Df1 to output the pulse control signal Pf1, and then the second pulse energization period T2
A signal for energizing the second pulse current value control signal Ip32 and a second base current setting signal Ib2 for a period corresponding to the second pulse width determined by the second pulse width setting signal Tp2 combined with the pulse width frequency signal Df2. Are switched by the second pulse width frequency signal Df2 to switch the pulse control signal Pf2.
To the welding power source control circuit PS.

(Explanation of FIG. 29) FIG. 29 is a block diagram of a fifteenth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 28 is omitted, and a different configuration will be described. First arc voltage setting circuit VS1 and second arc voltage setting circuit VS2
Is a circuit for setting an average value of each arc voltage in the first pulse energization period T1 and the second pulse energization period T2, respectively, and includes a first arc voltage setting signal Vs1 and a second arc voltage setting signal Vs1.
The arc voltage setting signal Vs2 is output. The arc voltage switching circuit SW6 switches between the signal Vs1 and the signal Vs2 by the switching signal Hc and outputs a switching arc voltage signal S6. The second comparison circuit CM2 receives the signal S1 and the arc voltage detection signal Vd of the arc voltage detection circuit VD as inputs, and outputs an arc voltage control signal Cm2 of the difference. The pulse current value control circuit IP3 receives the first arc voltage control signal Cm2 in the first pulse energization period T1 and the second arc voltage control signal Cm2 in the second pulse energization period T2 as inputs, and each has a first pulse current value IP31. And a first pulse current value control signal I corresponding to the second pulse current value IP32.
p31 and the second pulse current value control signal Ip32 are output.

The pulse frequency setting circuit FP1 has a pulse frequency setting signal Fp corresponding to the pulse period (D1 = D2).
Outputs 1. The pulse width setting circuit TP1 is a circuit for setting the pulse width and outputs the pulse width setting signal Tp1. The base current setting circuit IB1 is a circuit for setting the base current value and outputs the base current setting signal Ib1. The pulse frequency signal generation circuit VF receives the pulse frequency setting signal Fp1 as an input and generates a pulse frequency signal Vf1. The pulse width frequency signal generation circuit DF outputs a pulse width frequency signal Df1 composed of the pulse width setting signal Tp1 and the pulse frequency signal Vf1. In the first pulse energization period T1, the pulse base current switching circuit SW5 has a signal for energizing the pulse current value control signal Ip3 for a period corresponding to the pulse width determined by the pulse width setting signal combined with the pulse width frequency signal Df1. The base current setting signal Ib1 is switched by the pulse width frequency signal Df1 to output the pulse control signal Pf1. Next, in the second pulse energization period T2, the pulse width setting signal combined with the pulse width frequency signal Df1 is used. The signal for energizing the pulse current value control signal Ip3 and the base current setting signal Ib1 are switched by the pulse width frequency signal Df1 for a period corresponding to the fixed pulse width, and the pulse control signal Pf2 is output and input to the welding power source control circuit PS. .. The description below is the same as that of FIG.

(Explanation of FIG. 30) FIG. 30 is a block diagram of a sixteenth embodiment for carrying out the welding method of the present invention.

In the figure, the description of the same configuration as that of FIG. 28 is omitted, and a different configuration will be described. 30, a first configuration different from FIG. 28 is provided with a first arc voltage setting circuit VS1 and a second arc voltage setting circuit VS2 instead of the arc voltage setting circuit VS1, and the first arc voltage setting circuit VS1 and the second arc voltage setting circuit VS2, respectively.
A circuit for setting an average value of each arc voltage in the pulse energization period T1 and the second pulse energization period T2,
The arc voltage setting signal Vs1 and the second arc voltage setting signal Vs2 are output. The arc voltage switching circuit SW6 switches between the signal Vs1 and the signal Vs2 by the switching signal Hc and outputs a switching arc voltage signal S6. Second comparison circuit C
The M2 receives the signal S1 and the arc voltage detection signal Vd of the arc voltage detection circuit VD as inputs, and outputs an arc voltage control signal Cm2 of the difference. Pulse current value control circuit IP3
Is a first pulse current value IP31 and a second pulse current value, respectively, using the first arc voltage control signal Cm2 in the first pulse energization period T1 and the second arc voltage control signal Cm2 in the second pulse energization period T2 as inputs. The first pulse current value control signal Ip31 and the second pulse current value control signal Ip32 corresponding to IP32 are output.

A second configuration in FIG. 30 different from FIG. 28 is that instead of the average current setting circuit IM in FIG. 28, a first welding current setting circuit IM1 for outputting a first welding current setting signal Im1 and a second welding current setting circuit IM1. Second output current setting signal Im2
Welding current setting circuit IM2 and first welding current setting signal Im
The wire feeding speed switching circuit SW7 is provided for switching between 1 and the second welding current setting signal Im2 by the switching signal Hc and outputting the switching wire feeding speed signal S7 to the first comparing circuit CM1. The description below is the same as that of FIG.

[0140]

According to the pulse MAG arc welding method and the welding apparatus of the present invention described in claims 1 and 4, the first pulse energization period T1 in which the welding current of the first pulse current group is energized.
The arc length of the first arc length L1 and the arc length of the second pulse energization period T2 for energizing the pulse welding current of the second pulse current group is different from the first arc length L1 and the second arc length L2.
And the second welding speed WS2 during the second pulse energization period T2.
Is 1 of the first welding speed WS1 during the first pulse energization period T1.
/ 2 or less or zero and the welding speed is periodically switched in synchronism with the switching signal Hc between the first pulse energization period T1 and the second pulse energization period T2. In (1), while maintaining the aesthetic appearance of the weld bead, a welding method that does not cause burn-through or partial melt can be performed, and a uniform backside bead can always be obtained.

The pulse M of the present invention according to claims 2 and 4
According to the AG arc welding method and the welding apparatus, the arc length of the first pulse energization period T1 in which the welding current of the first pulse current group is energized is defined as the first arc length L1 and the pulse welding current of the second pulse current group is energized. The second arc length L2 is smaller than the first arc length L1 during the second pulse energization period T2.
And the second welding speed WS2 during the second pulse energization period T2.
Is 1 of the first welding speed WS1 during the first pulse energization period T1.
/ 2 or less or zero and by periodically switching the welding speed in synchronization with the switching signal Hc between the first pulse energization period T1 and the second pulse energization period T2, the plate thickness exceeding the root gap 2 [mm] is exceeded. It is possible to perform a welding method that does not cause burn-through or partial melting while maintaining the aesthetics of the appearance of the weld bead in back-side welding of butt joints, etc., and always obtain a uniform back-side bead.

The pulse M according to the present invention as defined in claims 3 and 4.
According to the AG arc welding method and the welding apparatus, the arc length of the first pulse energization period T1 in which the welding current of the first pulse current group is energized is defined as the first arc length L1 and the pulse welding current of the second pulse current group is energized. The second arc length L2, which is larger than the first arc length L1, during the second pulse energization period T2
And the second welding speed WS2 during the second pulse energization period T2.
Is 1 of the first welding speed WS1 during the first pulse energization period T1.
/ 2 or less or zero, and by periodically switching the welding speed in synchronization with the switching signal Hc between the first pulse energization period T1 and the second pulse energization period T2, a plate thickness having a root gap of 2 [mm] or less While maintaining the aesthetic appearance of the weld bead in backside welding of thin plate butt joints, etc.
A welding method that does not cause burn-through or partial melting can be performed, and a uniform back bead can always be obtained.

[Brief description of drawings]

FIG. 1 is a view showing an appearance of a “scaly bead” welded by a conventional TIG filler arc welding method.

FIG. 2 is a block diagram of a welding power source used in the MIG arc welding method of Prior Art 1 (Japanese Patent Publication No. 46-650).

FIG. 3 is a diagram showing external characteristics and arc characteristics of an output current and an output voltage of a welding power source used in the MIG arc welding method of Prior Art 1.

FIG. 4 is a MA of Prior Art 2 (Japanese Patent Publication No. 49-48057).
It is a figure which shows the external characteristic and arc characteristic of an output current and an output voltage used for a G welding method.

FIG. 5 is a waveform diagram of a welding current and a welding voltage by the pulse MIG welding method of the related art 3 (Japanese Patent Laid-Open No. 62-279087).

FIG. 6 is a diagram showing an appearance of a “scaly bead” produced by a conventional MIG arc welding method.

FIG. 7 is a view showing the appearance of the back bead and the penetration shape of the vertical cross section when the arc length L and the welding speed WS are changed in the welding method of the present invention.

FIG. 8 is a diagram showing the result of whether or not a weld bead is acceptable when the plate thickness T of the object to be welded and the root gap G are changed.

FIG. 9 is a view showing a welding method according to the present invention, wherein a second welding speed WS
It is a figure which shows a back bead result at the time of changing 2 and root gap G.

FIG. 10 is a view showing a back bead result when the second welding speed WS2 and the switching frequency F are changed in the pulse MAG arc welding method of the present invention.

FIG. 11 is a diagram showing the appearance of the back bead and the penetration shape of the vertical cross section when the arc length L and the welding speed WS are changed in the welding method of the present invention.

FIG. 12 is a view showing the result of whether or not a weld bead is acceptable when the plate thickness T of the object to be welded and the root gap G are changed.

FIG. 13 is a second welding speed W in the welding method of the present invention.
It is a figure which shows a back bead result when S2 and root gap G are changed.

FIG. 14 is a graph showing a second welding speed W in the welding method of the present invention.
It is a figure which shows a back bead result when S2 and the switching frequency F are changed.

FIG. 15 is a block diagram of a first embodiment for carrying out the welding method of the present invention.

FIG. 16 is a block diagram of a second embodiment for carrying out the welding method of the present invention.

FIG. 17 is a block diagram of a third embodiment for carrying out the welding method of the present invention.

FIG. 18 is a block diagram of a fourth embodiment for carrying out the welding method of the present invention.

FIG. 19 is a block diagram of a fifth embodiment for carrying out the welding method of the present invention.

FIG. 20 is a block diagram of a sixth embodiment for carrying out the welding method of the present invention.

FIG. 21 is a block diagram of a seventh embodiment for carrying out the welding method of the present invention.

FIG. 22 is a block diagram of an eighth embodiment for carrying out the welding method of the present invention.

FIG. 23 is a block diagram of a ninth embodiment for carrying out the welding method of the present invention.

FIG. 24 is a block diagram of a tenth embodiment for carrying out the welding method of the present invention.

FIG. 25 is a block diagram of an eleventh embodiment for carrying out the welding method of the present invention.

FIG. 26 is a block diagram of a twelfth embodiment for carrying out the welding method of the present invention.

FIG. 27 is a block diagram of a thirteenth embodiment for carrying out the welding method of the present invention.

FIG. 28 is a block diagram of a fourteenth embodiment for carrying out the welding method of the present invention.

FIG. 29 is a block diagram of a fifteenth embodiment for carrying out the welding method of the present invention.

FIG. 30 is a block diagram of a sixteenth embodiment for carrying out the welding method of the present invention.

[Explanation of symbols]

1 Consumable electrode (wire) PC1 1st pulse current group PC2 2nd pulse current group L Arc length L1 1st arc length L2 2nd arc length T1 1st pulse energization period T2 2nd pulse energization period Ws1 1st welding speed setting signal Ws2 Second welding speed setting signal Vd Arc voltage detection signal Hc Switching signal Vs1 (First) arc voltage setting signal Vs2 Second arc voltage setting signal Ip1 (First) pulse current value setting signal Ip2 Second pulse current value setting signal Ip31 , Ip32 First and second pulse current value control signal Im Average current setting signal Im1 First welding current setting signal Im2 Second welding current setting signal Ib1 (First) base current setting signal Ib2 Second base current setting signal Ib31, Ib32 First and second base current control signal Tp1 (first) pulse width setting signal Tp2 Second pulse width setting signal Cm1 Wire feeding speed control signal Cm2 Voltage control signal Syo Synchronous output setting signal Syi Synchronous input setting signal S1 Switching pulse current value signal S2 Switching pulse width signal S3 Switching base current signal S4 Switching pulse frequency signal S5 Switching pulse base current signal S6 Switching arc voltage signal S7 Switching wire feed Feed rate signal S11 Switching welding speed setting signals Pf1, Pf2 First and second pulse control signals f1, f2 First and second pulse frequencies f3 Pulse frequencies f31, f32 First and second pulse frequencies WS1 First welding speed (setting Circuit) WS2 Second welding speed (setting circuit) VD Arc voltage detection circuit HC Switching signal generation circuit PS Welding power supply control circuit CM1 Wire feed speed comparison circuit (first comparison circuit) CM2 (Second) comparison circuit SW1 Pulse current value Switching circuit SW2 Pulse width switching circuit SW3 Base current switching circuit SW4 Pulse frequency switching circuit SW5 pulse Base current switching circuit SW6 Arc voltage switching circuit SW7 Wire feeding speed switching circuit (welding current switching circuit) SW11 Welding speed switching circuit IP1 (first) pulse current value (setting circuit) IP2 Second pulse current value (setting circuit) IP3 Pulse current values IP31, IP32 First and second pulse current values TP1 (first) Pulse width (setting circuit) TP2 Second pulse width (setting circuit) TP3 Pulse widths TP31, TP32 First and second pulse width IB1 (first 1) Base current (setting circuit) IB2 Second base current (setting circuit) IB3 Base current (value) (control circuit) IB31, IB32 First and second base current values IM Average current setting circuit IM1 First welding current setting circuit IM2 Second welding current setting circuit SYO Synchronous signal output circuit SYI Synchronous signal input circuit WF, WF1, WF2, W 3 wire feed rate

Claims (4)

(57) [Claims] 1. A pulse MAG for periodically switching a first pulse current group for obtaining a first arc length (L1) and a second pulse current group for obtaining a second arc length (L2) by a switching signal.
In the arc welding method, the consumable electrode is fed at a preset constant wire feeding speed, and a period for conducting the welding current of the first pulse current group is referred to as a first pulse conduction period (T1), and the second pulse is used. A second pulse energization period (T2) is a period during which the welding current of the current group is applied, and the first arc length (L1) and the second arc length (L2) are different arc lengths (L), and the second The second welding speed (WS2) during the energization period (T2) is set to the first welding speed (WS2) during the first pulse energization period (T1).
The welding speed (WS1) is 1/2 or less or zero, and the first
The pulse energization period (T1) and the second pulse energization period (T
2) A pulsed MAG arc welding method in which the welding speed is periodically switched in synchronization with the switching signal (Hc). 2. The second arc length (L2) is set to an arc length (L) smaller than the first arc length (L1), and the plate thickness of the work piece exceeds 2 [mm]. The pulsed MAG arc welding method described in 1. 3. The second arc length (L2) is set to an arc length (L) larger than the first arc length (L1), and the plate thickness of the workpiece is 2 [mm] or less. The pulsed MAG arc welding method described in 1. 4. A pulse MAG for periodically switching a first pulse current group for obtaining a first arc length (L1) and a second pulse current group for obtaining a second arc length (L2) by a switching signal.
In an arc welding device, an arc voltage detection circuit (VD) that detects an arc voltage value and outputs an arc voltage detection signal (Vd), an arc voltage setting signal (Vs1) or a first arc voltage setting signal (Vs1) 2 Arc voltage setting signal (Vs2) and switching arc voltage signal (S6)
And a comparison circuit (CM) for comparing the arc voltage detection signal (Vd) and outputting a difference arc voltage control signal (Cm2).
2) Controlling a pulse frequency (f3) or pulse width (TP3), a base current value (IB3) or a pulse current value (IP3) corresponding to the arc voltage control signal (Cm2). A pulse-based current control circuit for outputting a pulse-based current control signal, and controlling with the pulse-based current control signal among four conditions of the pulse current value and pulse width of the first pulse current group and the pulse current value and the base current value. A first pulse base current setting circuit that sets three conditions excluding the conditions and outputs a first pulse base current setting signal, and a pulse current value, pulse width, pulse frequency, and base current value of the second pulse current group. The second pulse base current setting signal is output by setting three of the four conditions excluding the condition of controlling by the pulse base current control signal. A second pulse base current setting circuit for switching, a switching circuit (HC) for switching at a switching frequency F = 0.5 to 5 [Hz] and outputting a switching signal (Hc),
The first arc voltage setting signal (Vs1) and the second arc voltage setting signal (Vs2) are switched by the switching signal (Hc) to output a switching arc voltage signal (S6) or the first pulse base current. Setting signal and the second
One or more switching setting circuits for switching the pulse base current setting signal by the switching signal (Hc) to output the switching setting signal, or outputting both signals; the pulse base current control signal and the switching setting signal And a pulse control signal generating circuit for outputting a first pulse control signal (Pf1) and a second pulse control signal (Pf2), and a first pulse current when the first pulse control signal (Pf1) is input. Output the second pulse control signal (Pf2)
Is input, a welding power source control circuit (PS) that outputs a second pulse current group and the switching signal (Hc) are input,
A sync signal output circuit (SYO) for outputting a sync output setting signal (Syo); and a sync signal input circuit (SYI) for inputting the sync output setting signal (Syo) and outputting a sync input setting signal (Sii), A first welding speed setting circuit (WS1) that outputs a first welding speed setting signal (Ws1) corresponding to the first welding speed, and a second welding speed setting signal (Ws2) that corresponds to the second welding speed The second welding speed setting circuit (WS2), the first welding speed setting signal (Ws1) and the second welding speed setting signal (Ws2) are switched by the switching signal (Hc), and the switching welding speed setting signal (S11). ) Output welding speed switching circuit (SW11).