JP3079625B2 - MAG welding arc start control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a MAG welding arc starter for periodically changing an arc voltage or an arc voltage and a welding current in order to periodically change an arc length. It relates to a control method.

[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. In order for these welded joints to form the outer surfaces of these structures as they are, not only are the welded joints required to have high welding strength, but also the appearance of the weld beads is required to be good. I have. Therefore, as an arc welding method having a good weld bead appearance, a TIG arc welding method in which a filler wire is added has been widely used. However, this TIG arc welding method has a low welding speed. Poor production efficiency. Therefore, a proposal has recently been made to obtain a weld bead appearance having the same regular wave shape as the TIG arc welding method by the pulse MIG arc welding method.

As one of them, the present applicant has filed Japanese Patent Application No. 2-1.
1, a first arc voltage setting signal Vs1 of a first arc voltage setting circuit VS1 and a second arc voltage are shown in FIG. A second arc voltage setting signal Vs2 of the arc voltage setting circuit VS2 is used as a welding condition switching signal (hereinafter, referred to as a switching signal) of a welding condition switching circuit (hereinafter, referred to as a switching circuit) HL.
By switching at the switching frequency F of H1, FIG.
2 (A) and FIG. 3 (C), and a pulse current group as shown in FIG.
(B), the first arc length Lt and the second arc length Lr are switched as shown in FIGS. 3 (A) and 3 (B).

The MIG arc welding method for periodically changing the arc voltage or the arc voltage and the welding current, particularly the pulse MIG arc welding method of the prior application described with reference to FIG. In addition to obtaining a regular scaly bead appearance for aluminum described above, a regular scaly bead appearance is also obtained for copper or copper alloy.
The crystal grains are made finer than aluminum and cracks are less likely to occur.Blowhole is less generated than aluminum. Butt welding is performed even when the butt gap is large. Is less likely to occur, compared to lap fillet welding, even if the gap between the overlaps is large, it is difficult for one-sided melting to occur, the penetration shape can be controlled for stainless steel, and the progress of the weld bead The application range is expected to be expanded, for example, the penetration depth in the direction is substantially constant.

[0010]

SUMMARY OF THE INVENTION
G arc welding method and MAG arc welding method (hereinafter referred to as M
2 (A), 2 (B), 3 (A) and 3 (B), the tip 1a of a consumable electrode (hereinafter referred to as a wire) 1 is welded. Thing 2
When the arc 3 is generated by contacting with the welding start portion 5t, as shown in FIGS.
Because the workpiece 2 has not yet been sufficiently heated and melted,
The fusion between the weld metal 5 and the workpiece 2 is relatively poor. In particular, a material having a large thermal conductivity containing aluminum, copper or the like as a main component has poor fusion between the deposited metal 5 and the workpiece 2,
As shown in FIG. 4, at the welding start portion 5t, as shown in FIG. 4B, the height of the weld bead extra 5r is larger than that of the normal welded portion, and the weld bead width 5w. Are small as shown in FIG. 7C, and undercuts 5u and 5u are likely to occur as shown in FIG.

Referring to FIGS. 2 (A) to 2 (D) and 3 (A) to 3 (D), arc welding is performed by using a welding apparatus which carries out the MIG arc welding method of the prior application of FIG. The state at the time of starting will be described. FIG. 2 (A) shows an arc when the arc length determined by the small first arc voltage setting signal Vs1 is Lt, as shown in FIG. 2 (D).
It is a figure which shows the positional relationship between the wire tip 1a and the to-be-welded object 2 at the time of carrying out kustarto. FIG. 7B shows an arc length determined by a second arc voltage setting signal Vs2 having a large arc voltage setting value Vs after a period T1 described later has elapsed from the time ts at which the arc was started. It is a figure which shows the positional relationship between the wire front-end | tip 1a and the to-be-welded object 2 when switched so that it may become Lr. FIG. 3C shows the first pulse current group P1, P1,... Of the pulse frequency f1 (pulse period D1) determined by the first arc voltage setting signal Vs1 having a small arc length in the first pulse energizing period T1. After applying the current for the second time,
Is a diagram showing the time course of the welding current I when the second pulse current group P2, P2,... Of the pulse frequency f2 (pulse period D2) determined by the voltage setting signal Vs2 is applied for the second pulse application period T2. . The pulse current value Ip, pulse width Tp, and base current value Ib are the same for both the first and second pulse conduction periods T1 and T2. FIG. 3 (A)
Contrary to the case of FIG. 2A, as shown in FIG. 3D, the second arc voltage setting signal Vs having a large arc voltage setting value Vs.
FIG. 3 is a diagram showing a positional relationship between a wire tip 1a and a workpiece 2 when an arc start is performed when an arc length determined by 2 is Lr. FIG. 13B is switched so that the arc voltage set value Vs in the first pulse energizing period T1 becomes the arc length Lt determined by the small first arc voltage set signal Vs1 after the period T2. It is a figure which shows the positional relationship when it is. FIG. 2C shows the period between the elapsed times ts and t1 in FIG.
And t2 are interchanged.

As shown in a period T1 in FIGS. 2A and 2C and 2D, the first set voltage Vs having a small
When the arc start is performed from the arc voltage setting signal Vs1, the heat input is insufficient due to the small arc length Lt, and the workpiece 2 is not sufficiently heated and melted. Poor fusion as shown in FIGS. 4A to 4C is likely to occur. Conversely, as shown in a period T2 in FIGS. 3A and 3C and 3D, the arc voltage set value V
When the arc is started from the second arc voltage setting signal Vs2 having a large s, since the arc length is Lr and large, the heating and melting are started in a state where the arc is widened. Since the material has not been heated yet, electrons are hardly emitted from the oxide film in the aluminum material, and the cleaning action for removing the oxide film is insufficient, so that the blow
Occurs.

[0020]

An arc star according to claim 1 is provided.
The first and second arc voltage setting circuits VS1
And the set value Vs of VS2 are changed to the first value having a small arc length Lt.
In a MAG welding arc start control method for performing welding by periodically changing an arc voltage set value Vs1 and a second arc voltage set value Vs2 having a large arc length Lr, the first arc is controlled. −
The arc start is performed at the arc voltage determined by the third arc voltage set value Vs3 between the arc voltage set value Vs1 and the second arc voltage set value Vs2, and the arc required at the start of welding is obtained. By setting the length to a length, the object to be welded is heated and melted by appropriate heat input, and the cleaning action for removing the oxide film is continued for 0.5 to 1 second.
MAG welding arcer which switches to a periodic change of the arc voltage setting values Vs1 and Vs2, changes the wire protrusion length to periodically change the arc length by 3 mm or more, and welds only by spray transition. Control method.

According to a second aspect of the present invention, there is provided an arc start control method, wherein the third arc voltage set value Vs3 of the first embodiment is changed to a set signal of the first arc voltage set value Vs1 and the second arc voltage. Set value Vs
2 is a MAG welding arc start control method which is set by the start voltage setting signal Avs of the start voltage automatic setting circuit AVS with the setting signal of 2 as an input. Are omitted to simplify the setting.

According to a third aspect of the present invention, there is provided an arc start control method comprising the steps of: setting the third arc voltage set value Vs3 to the first arc voltage set value Vs1;
A MAG welding arc start control method which is set by a setting signal of s2 and a setting signal for fine adjustment within a predetermined range between the signals Vs1 and Vs2, wherein the arc is finely adjusted according to a difference of a workpiece. The start voltage can be set.

[0030]

The arc start control method of the present invention will be described with reference to FIG. FIG. 5E shows the arc length L of FIG.
The first arc voltage set value Vs1 in FIG.
And a second arc voltage set value Vs2 for increasing the arc length Lr in FIG. 9B, and a third arc having an arc length of Lm.
The arc start is performed at time ts by the arc voltage set value Vs3, and the arc is started until time ts <t ≦ ta.
FIG. 6 is a diagram showing a positional relationship between a wire tip 1a and a workpiece 2 during a period Ts. FIG. 3C shows an arc start period T.
In step s, in order to obtain an intermediate arc length Lm, for example, an arc start pulse current group P3, P3,... having a pulse frequency f3 (pulse period D3) is energized. In the pulse energizing period T1, the pulse frequency f1 (pulse period D1) is similarly obtained in order to obtain a short arc length Lt.
Of the first pulse current group P1, P1,.
In the pulse energizing period T2, the pulse frequency f2 (pulse period D2) is similarly obtained in order to obtain a long arc length Lr.
7) is a diagram showing the time course of the welding current I when the second pulse current groups P2, P2,. In FIG. 10C, the pulse current value Ip, the pulse width Tp, and the base current value Ib are the same in the periods T1 and T2, and the respective frequencies are f2>f3> f1. The third arc voltage set value Vs3 in the arc start control method of the present invention may be, for example, 1/2 (Vs1 + Vs2). In order to periodically change the arc length Lt and the arc length Lr, the pulse frequency is set to f1
And f2 have been described. However, as will be described later with reference to a block diagram of a welding apparatus for implementing the arc start control method of the present invention, there are various changing methods.

[0040]

FIG. 6 (Z) is a view showing a welding result when lap fillet welding is performed by the welding apparatus having no third arc voltage set value of the prior application of FIG. 1, and FIG. 6 (Y). , (X) and (A) can set the third arc voltage set value Vs3.
The arc start period Ts can be set to 0.2 seconds, 0.4 seconds, and 0.5 seconds by the welding device shown in FIG.
It is a figure which shows the welding result at the time of performing lap fillet welding in seconds. The welding conditions in FIGS. (X) to (Z) and (A) are as follows. An aluminum material A5052 having a thickness of 3 [mm] was welded to an aluminum wire A5183 having a diameter of 1.2 [mm] with an average welding current of 100 [A] and an average arc voltage of 19 [V] at a welding speed of 40 [cm / cm2]. mi
n], the welding current of the pulse current group shown in FIG. Note that the arc length L shown in FIG.
m, Lt and Lr are respectively about 5 [mm] and 3 [m
m] and 7 [mm].

The arc start period Ts = 0 shown in FIG.
In the second, the extra 5r and the upper plate 2a and the lower plate 2b both have a substantial fusion defect 5u and are overwrapped, and at Ts = 0.2 seconds in FIG. Board 2
b, a substantial fusion failure 5u has occurred. Also, at Ts = 0.4 [sec] in FIG. 7 (X), a slight fusion failure 5u is still seen on the lower plate 2b, and Ts = 0.5 in FIG.
At [sec], the inclined surface of the extra bank 5r becomes flat, and no defective fusion or undercut is observed at all. Therefore,
In the arc start control method of the present invention, the arc start period Ts needs to be 0.5 seconds or more.

FIGS. 7 (Z), (A), (B) and (Q)
Is the arc start period Ts under the same welding conditions as in FIG.
With the welding equipment set to 0, 0.5, 1.0 and 1.5 seconds,
Welding bead when welding bead 5 is formed on workpiece 2
It is a figure which shows the external appearance above a gate. FIG. 7 (Z) shows a case where a welding device having no third arc voltage setting circuit of the prior application is used, and a welding bead having a narrow welding bead width 5w at a welding start portion 5t is formed. It became a bead and caused considerable fusion failure. (A) and (B) of FIG.
s = 0.5 seconds and 1.0 seconds, between which the welding start part 5
A flat weld bead can be obtained without causing poor fusion at t. Further, as shown in FIG.
At 1.5 seconds, the weld bead width 5w of the welding start portion 5t is larger than the normal weld bead width. Therefore, the arc start period Ts in the arc start control method of the present invention is suitably 0.5 to 1.0 second.

(Welding Apparatus for Implementing the Arc Start Control Method of the Present Invention) FIGS. 8 to 10 show a welding apparatus for implementing the arc start control method of the present invention by a MAG welding method without pulses. FIG. 11 to FIG. 13 are block diagrams of a welding apparatus for implementing the arc start control method of the present invention by a pulse MAG welding method. FIG.
(A) to (D) are diagrams showing the time course of the output signal of each circuit of FIGS. 11 to 13, and FIGS. 15 and 16 are the start voltage automatic setting circuit AVS of the block diagram of FIG.
The connection diagram of the embodiment of FIG.

(Description of FIG. 8) In FIG.
With C as an input, an output is supplied from the welding output control circuit PS having a constant voltage characteristic between the power supply tip 4 of the wire 1 and the workpiece 2 to generate the arc 3. The wire 1 is supplied from a wire feed roller WR rotated by a wire feed motor WM. The average welding current setting circuit IM is a wire feed mode.
And outputs an average welding current setting signal Im for setting an average value of the welding current determined by the wire feeding speed of the wire WM. The wire feed control circuit WC compares a signal Im with a speed detection signal Wd of a wire feed speed detector WD for detecting the rotation speed of the wire feed motor WM.
Of the wire feed motor WM with the comparison signal Cm1 of
To output the wire feed voltage Wc. The first arc voltage setting circuit VS1 and the second arc voltage setting circuit VS2 are circuits for setting the arc voltage under the first welding condition and the arc voltage under the second welding condition, respectively. 1-
Voltage setting signal Vs1 and second arc voltage setting signal Vs
Outputs 2. The switching circuit HL outputs a switching signal Hl for switching between the first welding condition and the second welding condition. The arc voltage switching circuit SW1 switches the signals Vs1 and Vs1 by the switching signal Hl.
s2 and outputs an arc voltage switching signal S1.

The welding current detection circuit ID detects the arc at time ts.
After the start, a welding current detection signal Id shown in FIG. The third comparison circuit CM3 is shown in FIG.
As shown in the figure, a welding current energizing signal Cm3 of the difference between the signal Id and the reference signal Vr of the reference signal generating circuit VR is output.
Arc start timed circuit (hereinafter referred to as AS timed circuit)
As shown in FIG. 14 (D), TM3 outputs an arc start completion signal (hereinafter, referred to as an AS completion signal) Tm3 at a time t5 when the arc start period Ts has elapsed with the signal Cm3 as an input. I do. Third arc voltage setting circuit V
In step S3, a third arc voltage setting signal Vs3 set to an appropriate voltage value for an arc start between the first arc voltage setting value Vs1 and the second arc voltage setting value Vs2 is supplied. Output.
The arc start welding voltage switching circuit (hereinafter referred to as SW voltage switching circuit) SW5 outputs the third arc voltage setting signal Vs3 connected to the contact b until the AS completion signal Tm3 is input. When the signal Tm3 is input, the contact a
To output the aforementioned arc voltage switching signal S1. Therefore, the switching arc start welding voltage signal (hereinafter referred to as the switching SW voltage signal) output by the switch SW5.
S5 outputs the third arc voltage setting signal Vs3 during the arc start period Ts as shown in FIG. 14B, and after the period Ts, the period of the switching frequency F of the switching signal Hl Thus, the first and second arc voltage setting signals Vs1 and Vs
Outputs 2. The second comparison circuit CM2 receives the signal S5 and the welding voltage detection signal Vd of the welding voltage detection circuit VD as inputs and outputs an arc voltage control signal Cm2 representing the difference therebetween. During the arc start period Ts, the welding output control circuit PS receives the arc voltage control signal Cm2 corresponding to the third arc voltage setting signal Vs3 as an input and the third arc suitable for the arc start. -Output voltage, and after the elapse of the period Ts,
Signals Vs1 and Vs2 switched by switching signal Hl
An arc voltage control signal Cm2 corresponding to the above is input, and the first arc voltage and the second arc voltage are periodically switched.
The first arc length and the second arc length are alternately changed.

(Explanation of FIG. 9) FIG. 9 is a block diagram of a second embodiment of a welding apparatus for implementing the MAG welding arc start control method of the present invention. The configuration different from FIG.
Instead of the average welding current setting circuit IM, a first average welding current setting circuit IH that outputs a first welding current setting signal Ih under the first welding condition, and a second welding current setting signal Il under the second welding condition are used. The second average welding current setting circuit IL to be output and the first welding current setting signal Ih and the second welding current setting signal Il are switched at the switching frequency F of the switching signal Hl, and the arc start welding current switching described later is performed. Circuit (hereinafter,
A welding current switching signal S is supplied to SW4 (referred to as SW current switching circuit).
3 is added. The SW current switching circuit SW4 is set to an arc start current setting circuit (hereinafter referred to as an AS current setting circuit) IM connected to the contact b until the AS completion signal Tm3 described above with reference to FIG. An arc start current setting signal Im (hereinafter, referred to as an AS current setting signal) Im is output. After the signal Tm3 is input, the contact is switched to the contact a and the above-described welding current switching signal S3 is output.

In the welding apparatus shown in FIG. 9, during the arc start period Ts, the arc start is performed by the third arc voltage setting signal Vs3 and the AS current setting signal Im suitable for the arc start. After the arc start period Ts has elapsed, the first arc voltage setting circuit VS1 and the second arc voltage setting circuit VS2 are connected to the output signal H of the switching circuit HL.
1 to change the apparent arc length periodically, and by switching between the first average welding current setting circuit IH and the second average welding current setting circuit IL with the signal Hl, the switching frequency is 3 [Hz]. By changing the wire feeding speed under the first welding condition and the second welding condition by periodically changing the wire feeding speed in the range of the response, the arc voltage of the welding device shown in FIG. In addition to the effect of switching, the shape of the weld bead can be further controlled.

(Explanation of FIG. 10) FIG.
It is a block diagram of an example of a welding device which performs MIG arc welding in transition zone CC. Normally, when welding in the meso spray transition region, the welding output control circuit has a constant current characteristic, the wire feeding speed is a predetermined constant value, and the arc length is self-control specific to the arc. It is controlled to a substantially constant value by the action. When a short circuit occurs, the short circuit is discriminated and a short-circuit current larger than a normal welding current is supplied to re-ignite the arc. In the welding apparatus of the present embodiment, when performing MIG arc welding in the meso spray transition area CC, since the welding output has a constant current characteristic, in order to periodically switch the apparent arc length, the welding is performed. There are two methods of switching the set value of the current or switching the set value of the wire feeding speed. When the welding current set value is changed, the wire feed speed must be changed at the same time.
In this embodiment, a method is employed in which the apparent arc length is periodically changed by periodically switching the wire feeding speed.

In FIG. 10, a first wire feed speed setting circuit WH and a second wire feed speed setting circuit WL are circuits for setting an apparent arc length under the first and second welding conditions, respectively. , And outputs a first wire feed setting signal Wh and a second wire feed setting signal Wl. Switching circuit H
L outputs a switching signal Hl for switching between the first welding condition and the second welding condition. The wire feed speed switching circuit SW8 is
The signal Wh and Wl are switched by the switching signal Hl to output the feed speed switching signal S8.

An arc start wire feed speed setting circuit (hereinafter referred to as an AS feed speed setting circuit) WM is provided with an arc start wire feed setting signal (hereinafter, referred to as an AS feed speed) for setting a wire feed speed suitable for arc start. (Referred to as a setting signal) Wm. Arc start welding wire feed speed switching circuit (hereinafter referred to as SW feed speed switching circuit) SW
7 is an AS completion signal corresponding to the AS completion signal Tm3 described above.
Until the signal Tm5 is input, it is connected to the contact b to output the signal Wm. After the AS completion signal Tm5 is input, it switches to the contact a and outputs the feed speed switching signal S8. Therefore, a switching arc start welding wire feed speed signal (hereinafter, referred to as a switch SW feed speed signal) S7 output from this circuit SW7 outputs an AS feed setting signal Wm during the arc start period Ts, and outputs a period Ts Thereafter, the first and second wire feeding speed signals Wh and W1 are output at the cycle of the switching frequency F of the switching signal H1.

The first comparison circuit CM1 receives the signal S7 and the speed detection signal Wd as inputs and outputs a comparison signal Cm1.
The welding current setting circuit IS outputs a welding current setting signal Is, and the short-circuit current setting circuit IT outputs a short-circuit current setting signal It for supplying a current larger than the welding current during arcing. The short circuit determination circuit SD receives the arc voltage detection signal Vd output from the arc voltage detection circuit VD and outputs a short circuit determination signal Sd when a short circuit occurs. The short-circuit current switching circuit SW6 switches from the contact b to a when the short-circuit determination signal Sd is input, switches the welding current setting signal Is to the short-circuit current setting signal It, and outputs the switching current signal S6. Welding current comparison circuit CM6
Controls the welding current by inputting the switching current signal S6 and the welding current detection signal Id output by the welding current detection circuit ID, and inputting the welding current control signal Cm6 of the difference to the welding output control circuit PS. I do. As described above, in the MIG welding of aluminum in the meso spray transition area CC, the arc flies to a distance with an oxide film, and the actual arc length fluctuates greatly and the arc voltage fluctuates greatly. Since it is difficult to detect and control the arc length, as in the present embodiment, the wire feed speed is periodically switched so that the shortest distance between the consumable electrode tip 1a and the surface of the weld pool of the work piece is shortest. The penetration shape is controlled by changing the apparent arc length, which is the distance.

(Explanation of FIG. 11) FIG. 11 is a block diagram of a first embodiment of a welding apparatus for implementing the pulse MAG welding arc start control method.
The description of the same configuration as in FIG. 8 is omitted. In the figure, a pulse current value setting circuit IP is provided with a pulse current value setting signal Ips.
And the base current setting circuit IB outputs a base current setting signal Ibs. The pulse width setting circuit TP outputs a pulse width setting signal Tps. During the arc start period Ts
In this case, the pulse frequency signal generation circuit VF generates a pulse frequency control signal corresponding to the arc voltage control signal Cm2 determined by the third arc voltage set value Vs3 and the arc voltage value Vd.
(Hereinafter referred to as a third pulse frequency control signal).
You. The pulse width frequency signal generation circuit DF sets the pulse width
A third signal comprising the signal Tps and the third pulse frequency control signal
Pulse width frequency control corresponding to arc voltage set value Vs3
Signal (hereinafter referred to as a third pulse width frequency control signal).
Power. The pulse base current switching circuit SW2
The flow value setting signal Ips and the base current setting signal Ibs are
Repeat at the frequency f3 determined by the third pulse width frequency control signal
The pulse output control circuit PS outputs a return pulse control signal.
To enter. After the elapse of the arc start period Ts
Is the pulse frequency signal generation circuit VF is the first arc voltage
Set value Vs1 and arc voltage value Vd or second arc voltage setting
The first pulse frequency control signal Vf1 under the first welding condition and the second pulse frequency control signal Vf1 under the second welding condition correspond to the arc voltage control signal Cm2 determined by the constant value Vs2 and the arc voltage value Vd .
The pulse frequency control signal Vf2 is switched and output at the switching frequency F of the switching signal H1. The pulse width frequency signal generation circuit DF includes a first pulse width frequency control signal Df1 corresponding to a first welding condition including a pulse width setting signal Tps and a first pulse frequency control signal Vf1, and a second pulse width corresponding to a second welding condition. And a two-pulse width frequency control signal Df2. Under the first welding condition, the pulse base current switching circuit SW2 converts the pulse current value setting signal Ips and the base current setting signal Ibs into the first pulse width frequency control signal Df.
Pulse control signal Pf1 repeated at frequency f1 determined by 1
And then, in the second welding condition, the signal I
ps and the signal Ibs by the second pulse width frequency control signal D
A pulse control signal Pf that repeats at a frequency f2 determined by f2
2 is output to the welding output control circuit PS.

(Explanation of FIG. 12) FIG. 12 is a block diagram of a second embodiment of a welding apparatus for implementing the pulse MAG welding arc start control method of the present invention. 11 is different from FIG. 11 in that the average welding current setting circuit IM shown in FIG.
AS current setting circuit IM that outputs AS current setting signal Im
And the first welding current setting signal Ih under the first welding condition
And a second average welding current setting circuit IH for outputting a second welding current setting signal Il under the second welding condition.
The average welding current setting circuit IL and the first welding current setting signal Ih and the second welding current setting signal Il are switched at the switching frequency F of the switching signal Hl, and the welding current is supplied to the SW current switching circuit SW4 described above with reference to FIG. A welding current switching circuit SW3 for outputting a switching signal S3 is added.

The SW current switching circuit SW4 outputs the AS current setting signal Im set in the AS current setting circuit IM connected to the contact b until the AS completion signal Tm3 described above with reference to FIG. After the signal Tm3 is input, the contact is switched to the contact a, and the above-described welding current switching signal S3 is output.

The third pulse current value setting circuit IP3 has an
Third pulse current value setting signal Ip3 s suitable for starter
Is output. The arc start welding (hereinafter, referred to as SW) pulse current value switching circuit SW4-1 outputs the signal Ip3s connected to the contact b until the AS completion signal Tm3 is input, and outputs the signal Tm3. Is input, the contact is switched to a, and the signal Ips is output. Therefore, the switching SW pulse current value signal Ipa output from the circuit SW4-1 is in the arc start period Ts.
The signal Ip3s is output, and after the period Ts, the first and second pulse current value setting signals Ip1s and Ip2s are output at the cycle of the switching frequency F of the switching signal H1. The third base current setting circuit IB3 outputs a third base current setting signal Ib3s suitable for the arc start. The SW-based current switching circuit SW4-2 outputs the signal Ib3s connected to the contact b until the AS completion signal Tm3 is input,
After the signal Tm3 is input, the contact is switched to the contact a to output the signal Ibs. Therefore, this circuit SW4-2
The switching SW-based current signal Iba output by the first switching circuit Hb outputs the signal Ib3s during the arc start period Ts, and after the period Ts, the first and second switching SW-based current signals Ib at the switching frequency F of the switching signal Hl. The 2-base current setting signals Ib1s and Ib2s are output. The third pulse width setting circuit TP3 outputs a third pulse width setting signal Tp3s suitable for the arc start. The SW pulse width switching circuit SW4-3 outputs the signal Tp3s connected to the contact b until the AS completion signal Tm3 is input, and switches to the contact a after the signal Tm3 is input. The signal Tps is output. Therefore, the switching SW pulse width signal Tpa output from the circuit SW4-3 outputs the signal Tp3s during the arc start period Ts, and after the period Ts, the switching SW pulse width signal Tpa has the cycle of the switching frequency F of the switching signal Hl. , The first and second pulse width setting signals Tp
Output 1s and Tp2s.

In the welding apparatus shown in FIG. 12, during the arc start period Ts, the third arc suitable for the arc start is provided.
Voltage setting signal Vs3 and third pulse current value setting signal Ip
The arc start is performed by one or more of 3 s, the third base current setting signal Ib3 s and the third pulse width setting signal Tp3 s, or a combination of one or more of them and the AS current setting signal Im. After the elapse of the start period Ts, the first
The arc voltage setting circuit VS1 and the second arc voltage setting circuit V
The apparent arc length is changed periodically by switching S2 with the switching signal Hl of the switching circuit HL.
Further, the welding apparatus of FIG. 12 switches between the first average welding current setting circuit IH and the second average welding current setting circuit IL by the signal Hl, and changes the wire feeding speed at the switching frequency of about 3 [Hz] to the responsiveness. By changing the welding current under the first welding condition and the second welding condition by periodically switching within the allowable range, in addition to the effect of the arc voltage switching of the welding device shown in FIG. Can be controlled.

In the welding device shown in FIG. 12, the first average current setting circuit IH and the second average current setting circuit IL are switched to switch the wire feeding speed, thereby changing the pulse frequency to change the welding current. In addition to this, another pulse current value setting circuit IP2, a pulse width setting circuit TP2, or both of them, or another base current setting circuit IB2 is provided, and a pulse current value switching circuit SW3-1 and a base current setting circuit IB2 are provided.
Current switching circuit SW3-2 or pulse width switching circuit SW3
-3.

(Explanation of FIGS. 13, 15 and 16) FIG.
FIG. 3 is a block diagram of a third embodiment of a welding apparatus for implementing the pulse MAG arc start control method according to the present invention, which is a third arc voltage setting circuit in the block diagrams of FIGS. The start voltage setting signal A output from the start voltage automatic setting circuit AVS with the third arc voltage setting of VS3 as input and the setting signals of the first and second arc voltage setting values as inputs.
The setting is automatically made by vs. FIG.
5 is a connection diagram of the embodiment of the start voltage automatic setting circuit AVS of the block diagram of FIG. 13, and FIG. 16 is a circuit diagram of the connection diagram of FIG. FIG.

In the block diagram of FIG. 13, a circuit different from the block diagram of FIG. 11 is that the first and second arc voltage setting signals Vs1 and Vs2 are used instead of the third arc voltage setting circuit VS3 of FIG. As input, start voltage setting signal A
An automatic start voltage setting circuit AVS for outputting a vs. voltage is used. FIG. 15 is a circuit diagram of the circuit AV shown in FIG.
FIG. 4 is a connection diagram of the embodiment of FIG. 3A, in which first and second arc voltage setting signals Vs1 and Vs2 are input and the first and second arc voltage setting signals Vs1 and Vs2 are input;
The circuit comprises operation circuits OP1 and OP2, resistors R and 2R, and outputs a start voltage setting signal Avs. First
The operation circuit OP1 is an adder with a gain of 1/2, and its output is-(Vs1 + Vs2) / 2. The second operation circuit OP2 is an inverting amplifier with a gain of 1 for inverting the output of the circuit OP1, and its output value is (Vs1 + Vs2).
/ 2. FIG. 16 adds a fine adjustment setting device VE indicated by a dotted line to the connection diagram of FIG. This fine adjustment setting device V
By connecting both terminals of E to a power supply having voltage values of + Ve and -Ve, respectively, the start voltage setting signal Avs
Is 1/2 (Vs1 + Vs2) ± Ve.

[0100]

According to the arc start control method of the present invention,
An arc start is performed at an arc voltage determined by a third arc voltage set value between the first arc voltage set value and the second arc voltage set value. By setting the arc length, the work to be welded is heated and melted by an appropriate heat input, and a cleaning action for removing the oxide film is performed on the aluminum material for 0.5 to 1.5 seconds. Also, no blowhole is generated at the welding start portion, and further, in MAG welding of not only aluminum material but also steel type materials, poor fusion occurs at the welding start portion, or a projection is formed. No overfilling, no weld defects such as overwrap, undercut, etc. occur, and both the appearance and width of the weld bead are the same as those during stable welding. The shape is obtained.

According to a second aspect of the present invention, there is provided an automatic start voltage setting circuit which receives a setting signal of a first arc voltage setting value and a setting signal of a second arc voltage value as inputs. Since the start is performed by the start voltage setting signal, the setting operation by the operator is omitted, thereby preventing erroneous setting or simplifying the setting.

According to a third aspect of the present invention, in the arc start control method, the third arc voltage set value, the first and second arc voltage set values, and the first arc voltage set value are set. Since the first and second arc voltage values are set by a fine adjustment setting signal within a predetermined range between the first and second arc voltage set values, the first and second arc voltage values are only about 0.5 to 3 [V]. In the MAG welding method to which the arc start control method of the present invention is applied, the arc start can be finely adjusted according to the workpiece without erroneous setting.
Can be set.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a prior art MIG for welding by periodically changing an arc voltage in order to periodically change an arc length.
It is a block diagram of a welding device used for an arc welding method.

FIGS. 2 (A) to 2 (D) each show a case where the arc length is reduced from Lt having a small arc length using the welding apparatus shown in FIG. 1 as shown in FIG. 2 (A). After that, a diagram showing the positional relationship between the wire tip 1a and the workpiece 2 when the arc length is switched to a large arc length Lr as shown in FIG. FIG. 3 is a diagram illustrating a time course of a set value Vs of an arc voltage setting signal.

FIGS. 3 (A) to 3 (D) are opposite to the case of FIG. 2;
As shown in FIG. 7A, after the arc length starts from Lr with a large arc length, the position when the arc length switches to Lt with a small arc length as shown in FIG. FIG. 3 is a diagram showing a relationship, a diagram showing a time course of a welding current I, and a diagram showing a time course of a set value Vs of an arc voltage setting signal.

4 (A) to 4 (C) are respectively a cross-sectional view and a vertical cross-sectional view of a welding start portion when an arc start is performed using the welding apparatus of FIG. 1, and FIG. It is an external view.

FIG. 5 (E) shows a short arc length Lt in FIG. 5 (A) and a long arc length Lr in FIG. 5 (B) applied to the arc start control method of the present invention. FIG. 6 is a diagram showing a positional relationship between a wire tip 1a and a workpiece 2 when an arc start is performed at a set value for setting an arc length Lm between the wire lengths Lm and Lm. FIG.
FIG. 9 is a diagram showing the time course of a welding current I to be supplied during an arc start period Ts, a first pulse conduction period T1, and a second pulse conduction period T2. FIG. 3D shows the period Ts and the period T.
FIG. 7 is a diagram showing the time course of an arc voltage set value Vs in 1 and a period T2.

FIG. 6 is a diagram showing a welding result when lap fillet welding is performed by a welding apparatus having no third arc voltage setting circuit of the prior application and setting a third arc voltage set value Vs3. The arc start period Ts using a welding device capable of
FIG. 3 is a diagram showing welding results when lap fillet welding is performed for 0.2, 0.4 and 0.5 seconds, respectively.

FIG. 7 shows an arc start period Ts using a welding device capable of setting a third arc voltage set value;
Is set to 0, 0.5, 1.0, and 1.5 seconds to show the appearance when a weld bead is formed on the flat plate 2. FIG.

FIG. 8 is a block diagram of a first embodiment of a welding apparatus for implementing the arc start control method of the present invention by a MAG welding method without a pulse.

FIG. 9 is a block diagram of a second embodiment of a welding apparatus for implementing the arc start control method of the present invention by a MAG welding method without a pulse.

FIG. 10 is a block diagram of a third embodiment of a welding apparatus for performing the arc start control method of the present invention by a MAG welding method without a pulse.

FIG. 11 shows a method of controlling the arc start according to the present invention by using a pulse M;
FIG. 2 is a block diagram of a first embodiment of a welding device implemented by an AG welding method.

FIG. 12 shows a pulse start control method according to the present invention.
It is a block diagram of a 2nd example of a welding device implemented by the AG welding method.

FIG. 13 shows a method of controlling the arc start according to the present invention by using a pulse M;
It is a block diagram of a 3rd example of a welding device implemented by an AG welding method.

14A to 14D are FIGS. 8 to 13;
FIG. 5 is a diagram showing a time course of an output signal of each circuit of FIG.

FIG. 15 is a connection diagram of a specific embodiment of the automatic start voltage setting circuit AVS of the block diagram of FIG. 13;

16 is a star with a fine adjustment setting device in the block diagram of FIG. 13;
FIG. 4 is a connection diagram of a specific embodiment of the automatic voltage setting circuit AVS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Consumable electrode (wire) 1a Consumable electrode (wire) tip 2 Workpiece 3 Arc 4 Power supply tip 4a Power supply tip 5 Weld metal (weld bead) 5t Weld start part 5r Excessive part 5u Incomplete fusion (under) -Cut) 5w Weld bead width P1, P1, ... at the welding start part First pulse current group P2, P2, ... Second pulse current group P3, P3, ... Pulse current group for arc start T1 First Pulse conduction period T2 Second pulse conduction period Ts Ark start period f1 First pulse frequency D1 First pulse period f2 Second pulse frequency D2 Second pulse period f3 Third pulse frequency D3 Third pulse period Ip Pulse current value Tp pulse width Ib base current value VS1 first arc voltage setting circuit Vs1 first arc voltage setting value (setting signal) VS2 second arc voltage setting circuit Vs2 second arc voltage Set value (setting signal) VS3 Third arc voltage setting circuit Vs3 Third arc voltage setting value (setting signal) AVS start voltage automatic setting circuit Avs start voltage setting signal IM Average welding current or star Current setting circuit Im Average welding current or start current setting signal IP3 Third pulse current value setting circuit IB3 Third base current setting circuit TP3 Third pulse width setting circuit SW4 SW current switching circuit SW4-1 SW pulse current Value switching circuit SW4-2 SW base current switching circuit SW4-3 SW pulse width switching circuit SW5 SW voltage switching circuit Ip3 s Third pulse current value setting signal Ib3 s Third base current setting signal Tp3 s Third pulse Width setting signal Ipa switching SW pulse current value signal Iba switching SW base current signal Tpa switching SW pulse width signal

Continuation of the front page (56) References JP-A-56-109169 (JP, A) JP-A-57-171574 (JP, A) JP-A-52-27039 (JP, A) JP-A-3-473 (JP) JP-A-53-119759 (JP, A) JP-A-58-93574 (JP, A) JP-A-61-212476 (JP, A) JP-B-43-427 (JP, B1) (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 9/067 B23K 9/00 B23K 9/09 B23K 9/10 B23K 9/173

Claims (3)

(57) [Claims] 1. Consumption at a predetermined constant wire feeding speed
At the same time as feeding the electrodes, the set values of the first and second arc voltage setting devices are changed to the first arc voltage set value with a small arc length and the second arc voltage with a large arc length. By periodically changing to the arc voltage setting value, the wire protrusion length between the power supply tip end of the consumable electrode and the consumable electrode end is changed, and the arc of the shortest distance between the consumable electrode end and the surface of the workpiece is changed. Consumable electrode that changes its length periodically by 3 mm or more and welds only by spray transfer
Formula MAG welding A - Kusuta - in DOO control method, the first
According to the first arc voltage set value and the second arc voltage set value.
And the value is the same as the first arc voltage set value.
A third arc which is a value between the second arc voltage set value and the third arc voltage set value.
A MAG welding arc start control method in which the arc voltage corresponding to the arc voltage set value is arc-started, and then the first and second arc voltage set values are switched to a periodic change. 2. A third A - the click voltage setting value, the first A - by the setting signal click voltage setting value, the first A - - setting signal click voltage setting value and the second A click voltage setting Value and the second
The MAG welding arc start control method according to claim 1, wherein the MAG welding arc start control value is automatically calculated to be a value between the set voltage value and the set voltage value . 3. A third arc voltage set value, a first arc voltage set value set signal, a second arc voltage set value set signal, and first and second arc voltage set values. The first arc power is supplied by a fine adjustment setting signal within a predetermined range between the values.
Between the pressure set value and the second arc voltage set value.
The MAG welding arc start control method according to claim 1 , wherein the calculation is performed automatically .