JP4012360B2 - Multi-electrode pulse arc welding control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-electrode pulse arc welding method in which two arcs are generated between two welding wires electrically insulated from one welding torch and a workpiece to be welded. The present invention relates to a multi-electrode pulse arc welding control method capable of suppressing the occurrence of an arc from becoming unstable due to mutual interference of arcs caused by forces acting between each other.
[0002]
[Prior art]
In the multi-electrode pulse arc welding method, two welding wires are fed through two electrically insulated contact tips provided on one welding torch, and two welding wires are connected between the welding wire and the work piece. Welding is performed by generating a pulse arc. In this welding method, since two welding wires are melted simultaneously, a high welding amount can be obtained, so that high-speed welding exceeding 4 [m / min] can be performed in thin plate welding. In multi-layer welding, the number of layers can be reduced and welding can be performed, and the efficiency of welding work can be increased. And since this welding method is a pulse arc welding method, there is little generation | occurrence | production of a spatter and a beautiful bead appearance can be obtained. This welding method can be used for various metals such as steel, stainless steel, and aluminum alloys. However, in the conventional multi-electrode pulse arc welding method, as described later, there is a problem to be solved that the arc generation state becomes unstable due to the mutual interference of the arc due to the force acting between the two arcs. Hereinafter, a conventional multi-electrode pulse arc welding control method and welding apparatus will be described.
[0003]
FIG. 1 is a configuration diagram of a conventional multi-electrode pulse arc welding apparatus (hereinafter referred to as a conventional welding apparatus). As shown in the figure, the welding apparatus includes a first welding power supply device APS, a first wire feeding device AWF, a second welding power supply device BPS, a second wire feeding device BWF, and a welding torch 4. It is configured.
A first contact tip A41 and a second contact tip B41, which are electrically insulated from each other, are mounted on the welding torch 4, and the first welding wire A1 and the second contact tip A41 are passed through these contact tips A41 and B41. The first welding wire B1 is fed and fed to generate the first arc A3 and the second arc B3 between the workpiece 2 and the workpiece 2. One molten pool 21 is formed by these two arcs.
[0004]
The first welding power source device APS is a general welding power source device for pulse arc welding, outputs a feed control signal Wc to the first wire feeding device AWF, and outputs the first welding wire A1 to the first welding wire A1. As a result, the first welding current AIw is energized. The first wire feeder AWF controls the feeding of the first welding wire A1 in accordance with the feeding control signal Wc. Further, the second welding power source device BPS and the second wire feeding device BWF are also the same as described above, and thus the description thereof is omitted.
[0005]
In the first welding power supply device APS and the second welding power supply device BPS described above, as will be described later with reference to FIG. 2, two controls of arc length control by voltage feedback control and current waveform control by current feedback control are performed simultaneously. ing. In the prior art, these controls are performed completely independently between the two power supply devices.
[0006]
FIG. 2 is a current / voltage waveform diagram showing output waveforms of the first welding power supply device APS and the second welding power supply device BPS described above. FIG. 4A shows the change over time of the first welding current AIw, FIG. 4B shows the change over time of the first welding voltage AVw, and FIG. 4C shows the second welding. The time change of the current BIw is shown, and FIG. 4D shows the time change of the second welding voltage BVw. The operation will be described below with reference to FIG.
[0007]
(1) Period from time t1 to t2 (first peak current conduction time ATp)
As shown in FIG. 6A, the first peak current AIp is energized during the first peak current energization time ATp. Usually, both the values of the first peak current energization time ATp and the first peak current AIp are set in advance so that the welding wire transfers one pulse per droplet by arc heat. Further, as shown in FIG. 5B, during the first peak current energization time ATp, the first peak voltage AVp corresponding to the first peak current AIp is between the first welding wire and the workpiece. Apply between.
[0008]
(2) Period from time t2 to t3
As shown in FIG. 5A, the first base current AIb set in advance is energized within a range in which droplet transfer does not occur from time t2 to time t3 when the first pulse period ATf period ends. The duration of the first pulse period ATf is a frequency modulation control or a pulse width modulation control based on an error between the average value of the first welding voltage AVw and the first voltage setting signal AVs set from the outside of the power supply device ( Automatically determined by voltage feedback control). In general, since the average value of the welding voltage and the arc length are in a proportional relationship, the voltage feedback control described above controls the arc length that has a significant effect on the welding quality.
Further, as shown in FIG. 4B, during this period, the first base voltage AVb corresponding to the first base current AIb is applied between the first welding wire and the workpiece.
During the period before time t1 and after time t3, welding by the first welding power source device APS is performed by repeating the operations of the above items (1) and (2).
[0009]
(3) Period from time t4 to t5 (second peak current conduction time BTp)
As shown in FIG. 6C, the second peak current BIp is energized during the second peak current energization time BTp. Usually, both the values of the second peak current energization time BTp and the second peak current BIp are set in advance so that the welding wire transfers one pulse per droplet by arc heat as described above. The two values are set to different values depending on the wire feed speed (the average value of the welding current), and therefore the average value of the first welding current AIw and the average value of the second welding current BIw Are different from each other, the first peak current conduction time ATp and the second peak current conduction time BTp are different from each other, and the first peak current AIp and the second peak current BIp are different from each other.
Further, as shown in FIG. 4D, during the second peak current conduction time BTp, the second peak voltage BVp corresponding to the second peak current BIp is between the second welding wire and the work piece. Apply between.
[0010]
(4) Period from time t5 to t6
As shown in FIG. 5C, the second base current BIb set in advance is energized within a range in which droplet transfer does not occur from time t5 to time t6 when the second pulse cycle BTf period ends. Usually, the value of the base current is set to a value that varies depending on the wire feed speed (average value of the welding current), so the average value of the first welding current AIw and the second welding current BIw are set. If the average value is different, the first base current AIb and the second base current BIb have different values.
The duration of the second pulse period BTf is the same as the above item (2) between the average value of the second welding voltage BVw and the second voltage setting signal BVs set from the outside of the power supply device. It is automatically determined by frequency modulation control by error or pulse width modulation control (voltage feedback control).
As shown in FIG. 4D, during this period, the second base voltage BVb corresponding to the second base current BIb is applied between the second welding wire and the workpiece.
During the period before time t4 and after time t6, welding by the second welding power source device BPS is performed by repeating the operations of items (3) and (4).
[0011]
Voltage feedback control and current waveform control for controlling energization of the welding current in the first welding power source device APS shown in the items (1) and (2) above, and items shown in the items (3) and (4) above. The voltage feedback control and the current waveform control in the welding power source device BPS 2 are performed completely independently. Therefore, the timing at which the first peak current AIp and the first base current AIb are energized and the timing at which the second peak current BIp and the second base current BIb are energized are shown in FIGS. ) Becomes at random as shown.
Note that the period in which the first base voltage AVb rises as shown in part (b) of FIG. 6B coincides with the energization period of the second peak current BIp, and the second base voltage BVb is similarly shown in FIG. The period of lifting as shown in part B) corresponds to the energization period of the first peak current AIp. This phenomenon occurs due to the mutual interference of the arc between the first arc and the second arc, and details will be described later with reference to FIG.
[0012]
FIG. 3 is a block diagram showing a circuit configuration of the first welding power supply device APS and the second welding power supply device BPS of the conventional technology described above. Hereinafter, each circuit block will be described with reference to FIG.
[0013]
The first welding power source device APS is composed of each circuit block within a range surrounded by a one-dot chain line, and these circuit blocks will be described below.
The output control circuit INV performs output control with a commercial power supply as an input, and supplies an output suitable for the arc load. In general, an inverter control circuit, a chopper control circuit, a thyristor phase control circuit, etc. are commonly used as the output control circuit INV. For example, the inverter control circuit includes a primary rectifier circuit that rectifies a commercial power supply, a smoothing circuit that smoothes a rectified rippled voltage, an inverter circuit that converts the smoothed DC voltage into high-frequency AC, It consists of a high-frequency transformer that steps down high-frequency alternating current to a voltage suitable for arc load, a secondary rectifier circuit that rectifies the stepped-down alternating current again, and a direct current reactor that smoothes the rectified rippled direct current. In accordance with a current error amplification signal Ei described later, a plurality of sets of power transistors forming the inverter circuit are controlled to perform output control.
[0014]
The voltage detection circuit VD detects the first welding voltage AVw and outputs a voltage detection signal Vd averaged. The first voltage setting circuit AVS is provided outside the power supply apparatus, and outputs a first voltage setting signal AVs. The voltage error amplification and amplification circuit EV amplifies an error between the voltage detection signal Vd as a feedback signal and the first voltage setting signal AVs as a target value, and outputs a voltage error amplification signal Ev. The V / F conversion circuit VF receives the voltage error amplification signal Ev as described above, performs V / F conversion, and outputs a V / F conversion signal Vf. The peak current conduction time setting circuit TP outputs a preset peak current conduction time setting signal Tp. The mono multivibrator MM becomes the High level only for the time set by the peak current conduction time setting signal Tp, triggered by the change of the V / F conversion signal Vf from the Low level to the High level in FIG. The aforementioned first pulse period signal ATf is output.
[0015]
A modulation circuit MC surrounded by a dotted line is formed by the voltage error amplification circuit EV, the V / F conversion circuit VF, the peak current energization time setting circuit TP, and the mono multivibrator MM. The modulation circuit MC receives the voltage detection signal Vd and the first voltage setting signal AVs as inputs, and outputs the first pulse period signal ATf by frequency modulation control based on an error between the signals. As this modulation method, pulse width modulation control is also used as a conventional technique in addition to the above frequency modulation control.
[0016]
The first peak current setting circuit AIP outputs a preset first peak current setting signal AIp. The first base current setting circuit AIB outputs a preset first base current setting signal AIb. The first switching circuit ASW is connected to the a side when the first pulse period signal ATf is at a high level, and outputs the first peak current setting signal AIp as the first current control setting signal AIsc. When the first pulse period signal ATf is at a low level, the first base current setting signal AIb is output as the first current control setting signal AIsc by being connected to the b side. The current detection circuit ID detects the first welding current AIw and outputs a current detection signal Id. The current error amplification circuit EI amplifies an error between the current detection signal Id as a feedback signal and the first current control setting signal AIsc as a target value, and outputs a current error amplification signal Ei. Output control is performed according to the current error amplification signal Ei, and the first welding voltage AVw is applied.
[0017]
The first feed speed setting circuit AWS is provided outside the power supply device and outputs a first feed speed setting signal AWs. The feed control circuit WC receives the first feed speed setting signal AWs and outputs a feed control signal Wc. The first wire feeder AWF controls the feeding of the first welding wire A1 in accordance with the feeding control signal Wc.
[0018]
Next, the description of the circuit blocks of the second welding power supply device BPS and the second wire feeding device BWF will be made by using the first welding voltage AVw and the first welding current AIw as the second welding voltage BVw and the second welding voltage BVw. 2 welding current BIw, first voltage setting circuit AVS and first voltage setting signal AVs, second voltage setting circuit BVS and second voltage setting signal BVs, first peak current setting circuit AIP and second voltage setting signal BVs. The first peak current setting signal AIp is used as the second peak current setting circuit BIP and the second peak current setting signal BIp, and the first base current setting circuit AIB and the first base current setting signal AIb are used as the second base current. The setting circuit BIB and the second base current setting signal BIb, the first pulse period signal ATf and the second pulse period signal BTf, the first switching circuit ASW and the first current control setting signal The Isc to the second switching circuit BSW and the second current control setting signal BISC, omitted since the same manner as each replaced. As a result, the second welding voltage BVw is applied by the second welding power source device BPS, and the second welding wire B1 is fed by the second wire feeding device BWF. A second arc B3 is generated between the object 2 and the second welding current BIw is energized.
[0019]
As described above, in the first welding power supply device APS and the second welding power supply device BPS, the voltage error amplification circuit EV that performs voltage feedback control and the current error amplification circuit EI that performs current feedback control are between the power supply devices. Since they are independent, the energization timing of the first welding current AIw and the second welding current BIw is at random as described above with reference to FIG.
[0020]
[Problems to be solved by the invention]
In the conventional multi-electrode pulse arc welding method described above, the arc length fluctuates due to the mutual interference between the arcs that deforms the arc shape due to the force acting between the two arcs, and the arc generation state is not good. A phenomenon of stabilization occurs. Hereinafter, the cause of the mutual interference of the arc will be described first, and then the problems of the prior art caused by the mutual interference of the arc will be described.
[0021]
FIG. 4 is a schematic diagram of an arc generating portion for explaining the force acting on the arc 3 generated independently. FIG. 6A shows a case where the shape of the generated arc 3 is a symmetric shape with the feeding direction (hereinafter referred to as feeding direction) ab of the welding wire 1 being a center line. ) Is a case where the shape of the generated arc 3 is not symmetrical with the feeding direction ab as the center line.
As shown in FIG. 2A, an arc 3 is generated between the welding wire 1 and the workpiece 2 and a welding current Iw is energized. This welding current Iw returns to the minus terminal after sequentially energizing the welding wire 1 → the arc 3 → the workpiece 2 from the plus terminal (not shown) of the welding power source device. A magnetic field as shown in FIG. 2A is formed by the current flowing through the welding wire 1. However, in this case, since the shape of the arc 3 is symmetrical, no force acts on the arc 3 by this magnetic field. On the other hand, a force for contracting the arc 3 (hereinafter referred to as a contracting force by the arc) FX acts as shown in FIG. Therefore, only the contraction force by the arc acts on the symmetrical arc.
[0022]
Next, in FIG. 8B, an asymmetrical arc 3 is formed between the welding wire 1 and the work piece 2 as shown in a second arc B3 in FIG. And the welding current Iw is energized. A magnetic field as shown in the figure is formed by the current passing through the welding wire 1. In this case, unlike FIG. 5A, the shape of the arc 3 is not symmetrical, and a force (hereinafter referred to as a magnetic field force) FY acts on the arc 3 by this magnetic field. On the other hand, a contraction force FX due to the arc acts on the arc 3 by a magnetic field formed by a current passing through the arc 3 as shown in FIG. The force FY due to the magnetic field acts to pull the arc 3 back in the feeding direction ab, and the contraction force FX due to the arc acts to maintain the shape of the arc. It returns to the symmetrical shape as shown in A) and has the property of maintaining the shape (arc rigidity). The magnitudes of the force FY due to the magnetic field and the contraction force FX due to the arc are proportional to the magnitude of the current value forming the magnetic field.
[0023]
Next, the force which acts between two arcs in the conventional multi-electrode pulse arc welding method will be described with reference to FIGS.
FIG. 5 is a current / voltage waveform diagram of the prior art multi-electrode pulse arc welding method, similar to FIG. 2 described above, and FIG. 5 (A) shows the time change of the first welding current AIw. FIG. 4B shows the time change of the first welding voltage AVw, FIG. 4C shows the time change of the second welding current BIw, and FIG. 4D shows the second welding current. The time change of the voltage BVw is shown. As described above, since the first welding current AIw and the second welding current BIw are energized at random, there are the following four combinations of energization of the peak current and the base current.
[0024]
That is, at time t1, the first peak current AIp is energized as the first welding current AIw, and the second peak current BIp is energized as the second welding current BIw. The mutual interference of arcs in this state will be described later with reference to FIG. Next, at time t2, the first base current AIb is energized as the first welding current AIw, and the second base current BIb is energized as the second welding current BIw. The mutual interference of arcs in this state will be described later with reference to FIG.
[0025]
Furthermore, at time t3, the first peak current AIp is energized as the first welding current AIw, and the second base current BIb is energized as the second welding current BIw. At time t4, contrary to the above, the first base current AIb is energized as the first welding current AIw, and the second peak current BIp is energized as the second welding current BIw. The mutual interference of arcs in these states will be described later with reference to FIG.
[0026]
FIG. 6 is a schematic diagram of the arc generating portion at the time t1 of FIG. 5 described above in which the first and second welding currents energized to the two arcs are both peak currents. Hereinafter, the mutual interference of arcs in this state will be described with reference to FIG.
As shown in the figure, the first welding wire A1 is energized by the first peak current AIp, and the first arc A3 is generated in a symmetrical shape as in the case of FIG. Yes. On the other hand, the second welding wire A2 is supplied with the second peak current BIp, and the second arc B3 is generated in a symmetric shape as described above.
[0027]
In this state, as in the case of FIG. 4A described above, the first arc A3 is not affected by the magnetic field generated by the first peak current AIp that energizes the first welding wire A1. Only the contraction force AFX1 due to the arc caused by the first peak current AIp energizing one arc A3 acts. In addition, a magnetic field is formed around the first arc A3 by the second peak current BIp passing through the second welding wire B1, and the first arc A3 is not symmetrical with respect to this magnetic field. Therefore, in addition to the contraction force AFX1 caused by the arc, a force AFZ1 caused by a magnetic field acts on the first arc A3. Normally, when the current values for energizing the two arcs are substantially equal, the contraction force AFX1 due to the arc, which is the force that maintains the arc shape, is greater than the force AFZ1 due to the magnetic field, which is the force that deforms the arc shape. The shape of the arc A3 is not changed. Similarly, the shape of the second arc B3 does not change.
[0028]
As described above, in the state at time t1, the contraction force (AFX1 and BFX1) due to its own arc is greater than the force due to the magnetic field (AFZ1 and BFZ1) that is interference from the other arc, so the arc shape does not change. That is, when a current having a value substantially equal to the two arcs is energized, there is almost no influence on the arc generation state due to the mutual interference of the arcs.
[0029]
FIG. 7 is a schematic diagram of the arc generating portion at time t2 in FIG. 5 described above in which both the first and second welding currents energized to the two arcs are base currents.
The state shown in FIG. 6 is the same as that in FIG. 6 described above, except that the current for passing the two arcs is changed from the peak current to the base current. That is, the contraction force (AFX2 and BFX2) due to its own arc is greater than the force (AFZ2 and BFZ2) due to the magnetic field which is interference from the other arc, so the arc shape does not change. Therefore, as in the case of FIG. 6, when a current having a substantially equal value is applied to two arcs, there is almost no influence on the arc generation state due to the mutual interference of the arcs.
[0030]
FIG. 8 is a schematic diagram of the arc generating portion at the time t3 of FIG. 5 described above in which the first peak current AIp is supplied to the first arc A3 and the second base current BIb is supplied to the second arc B3. FIG. 4A shows the arc generation state at time t3, and FIG. 4B shows the arc generation state immediately after time t3. Hereinafter, the mutual interference of arcs in this state will be described with reference to FIG.
[0031]
(1) As shown in FIG. 4A, the first welding wire A1 is supplied with the first peak current AIp, and the first arc A3 is generated as in the case of FIG. It occurs in a symmetrical shape. On the other hand, the second base current BIb is applied to the second welding wire A2, and the second arc B3 is generated in a symmetrical shape as in FIG. 4A.
[0032]
In this state, the contraction force AFX1 due to the arc caused by the first peak current AIp that energizes the first arc A3 acts on the first arc A3. Further, a force AFZ2 caused by a magnetic field generated by the second base current BIb that energizes the other second welding wire B1 acts on the first arc A3. Here, since the value of the first peak current AIp is considerably larger than the value of the second base current BIb, the contraction force AFX1 due to the arc is larger than the force AFZ2 due to the magnetic field, As a result, the shape of the first arc A3 does not change.
[0033]
On the other hand, the contraction force BFX2 due to the arc by the second base current BIb that energizes the second arc B3 acts on the second arc B3. Furthermore, a force BFZ1 due to a magnetic field caused by the first peak current AIp that energizes the other first welding wire A1 acts on the second arc B3. Here, since the value of the second base current BIb is considerably smaller than the value of the first peak current AIp, the contraction force BFX2 due to the arc is smaller than the force BFZ1 due to the magnetic field, and As a result, the shape of the second arc B3 is deformed as shown in FIG.
[0034]
{Circle around (2)} As shown in FIG. 5B, the shape of the first arc A3 does not change immediately after time t3 as in the case {circle around (1)}. On the other hand, since the second arc B3 is attracted in the direction of the first arc A3 by the operation of the above item (1), the cathode point of the arc moves from the point b to the point c as shown in FIG. As a result, the arc shape is also greatly deformed into an asymmetric shape. Since the state of the deformed second arc B3 is the same as the state described above with reference to FIG. 4B, the second arc B3 has a second force in addition to the force described in the above item (1). A force BFY2 due to the magnetic field generated by the second base current BIb that energizes the welding wire B1 is newly applied. As a result, BFZ1 = BFX2 + BFY2 is established, and the balance of the forces acting on the second arc B3 is maintained, so that the second arc B3 maintains the shape shown in FIG.
[0035]
Further, since the second arc B3 is deformed as shown in FIG. 5B and the arc length is changed from ab to ac, the arc length becomes longer than before the deformation. As the arc length becomes longer, the welding voltage value proportional to the arc length becomes larger. Therefore, as shown at time t3 in FIG. 5D, the value of the second welding voltage BVw rises higher than the normal value. Value.
[0036]
As described above, when the current value for energizing the other arc is larger than the current value for energizing the other arc, the own arc is attracted by the interference of the other arc, and its shape is deformed and the arc is deformed. The length also becomes longer. In particular, in pulse arc welding, since the peak current value is generally set to about 400 to 600 [A] and the base current value is set to about 30 to 60 [A], the current difference becomes considerably large, As a result, the mutual interference between the arcs is increased, and the deformation of the arc is also increased.
[0037]
(3) Contrary to the above items (1) and (2), the first base current AIb is applied to the first arc A3, and the second peak current BIp is applied to the second arc B3. At time t4 in FIG. 5 described above, the shape of the second arc B3 does not change, but the first arc A3 is attracted by the interference from the second arc B3, and the shape of the arc is deformed. As a result, the arc length becomes longer. Therefore, as shown at time t4 in FIG. 5B, the first welding voltage AVw rises and becomes a value larger than the normal value.
[0038]
As described above, when currents having substantially the same value are applied to the two arcs, the influence of the mutual interference between the arcs is small. The arc with the smaller value is greatly affected, and its shape is greatly deformed. When this latter state occurs, the arc generation state becomes unstable and the welding quality becomes poor, as will be described below.
That is, since the shape of the second arc B3 at time t3 in FIG. 5 described above and the shape of the first arc A3 at time t4 are deformed by the above-described mutual interference of the arc and the arc length is increased, The droplet transfer deviates from the stable state of 1 pulse / one droplet transfer and becomes unstable. As a result, a large amount of spatter is generated, the bead appearance is deteriorated, the penetration is poor, and the welding quality is remarkably deteriorated.
Furthermore, as shown at time t5 in FIG. 5, when the arc length becomes too long due to the mutual interference of the arcs described above, the arc cannot be maintained, and finally an arc break occurs. If arc breakage frequently occurs during welding, welding defects such as poor penetration and deterioration of the bead appearance occur.
[0039]
Accordingly, the present invention provides a multi-electrode pulse arc welding method that can suppress instability of an arc generation state caused by mutual interference between two arcs and can always obtain good welding quality. A control method and a welding apparatus are provided.
[0040]
[Means for Solving the Problems]
The invention of claim 1 at the time of filing is as shown in FIGS.
The first welding wire A1 and the second welding wire B1 that are electrically insulated from each other from one welding torch 4 are fed at a preset feeding speed, and the first welding wire A1 is preset. The energization of the first peak current AIp and the energization of the first base current AIb set in advance are repeated for one cycle, and the second peak current BIp set in advance is applied to the second welding wire B1. And the preset second base current BIb are energized in one cycle, and the first welding wire A1, the second welding wire B1 and the workpiece 2 are In the multi-electrode pulse arc welding control method for generating and welding arcs A3 and B3,
The second welding wire B1 is energized with the second peak current BIp during the first energization period of the first peak current AIp and the energization period of the first base current AIb is the second base. The current BIb is energized, and then the second base current BIb is energized during the second energization period of the first peak current AIp and the energization period of the first base current AIb. This is a multi-electrode pulse arc welding control method in which the second energization is repeated as one set and energized.
[0041]
The invention of claim 2 at the time of filing, as shown in FIG. 9 and FIG.
The application in which the feeding speed of the second welding wire B1 described in claim 1 at the time of filing is a value obtained by further fine-tuning a value obtained by multiplying a preset feeding speed of the first welding wire A1 by half. The multi-electrode pulse arc welding control method according to claim 1 of the present invention.
[0042]
The invention of claim 3 at the time of filing, as shown in FIG. 10 and FIG.
The first welding wire A1 and the second welding wire B1 that are electrically insulated from each other from one welding torch 4 are fed at a preset feeding speed, and the first welding wire A1 is preset. The energization of the first peak current AIp and the energization of the first base current AIb set in advance are repeated for one cycle, and the second peak current BIp set in advance is applied to the second welding wire B1. And the preset second base current BIb are repeatedly energized as one cycle, and the first welding wire A1, the second welding wire B1 and the workpiece 2 are In the multi-electrode pulse arc welding control method for generating and welding arcs A3 and B3,
The second welding wire B1 is energized with the second peak current BIp during the first energization period of the first peak current AIp and the energization period of the first base current AIb is the second base. The current BIb is energized, and then the second base current BIb is energized during the second energization period of the first peak current AIp and the energization period of the first base current AIb. This is a multi-electrode pulse arc welding control method in which the same energization is repeated until the nth, which is a preset integer of 3 or more, and the first to nth energization is repeated as one set.
[0043]
The invention of claim 4 at the time of filing is as shown in FIGS.
Application in which the feeding speed of the second welding wire B1 described in claim 3 at the time of filing is a value obtained by further finely adjusting a value obtained by multiplying a preset feeding speed of the first welding wire A1 by 1 / n. The multi-electrode pulse arc welding control method according to claim 3 of the present invention.
[0044]
The invention of claim 5 at the time of filing is as shown in FIGS.
The time length ATf of one cycle between the energization of the first peak current AIp and the energization of the first base current AIb energizing the first welding wire A1 described in claims 1 to 4 at the time of filing is the first At the time of filing determined by frequency modulation control or pulse width modulation control based on an error between a voltage detection signal AVd obtained by detecting the welding voltage AVw between the welding wire A1 and the workpiece 2 and a preset voltage setting signal AVs The multi-electrode pulse arc welding control method according to claim 1, claim 2, claim 3, or claim 4.
[0045]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
FIG. 9 is a current / voltage waveform diagram showing the multi-electrode pulse arc welding control method of the first embodiment (hereinafter referred to as the first embodiment) corresponding to the invention of claim 1 at the time of filing. FIG. 4A shows the change over time of the first welding current AIw, FIG. 4B shows the change over time of the first welding voltage AVw, and FIG. 4C shows the second welding. The time change of the current BIw is shown, and FIG. 4D shows the time change of the second welding voltage BVw. This figure shows the case where the magnification n of the pulse period described later is 2. Therefore, the second pulse period BTf of the second welding current BIw shown in FIG. 10C is n = 2 times the first pulse frequency ATf of the first welding current AIw shown in FIG. It becomes a cycle. Hereinafter, the operation in each period will be described with reference to FIG.
[0046]
In the first arc, energization of the first peak current AIp during the period of time t1 to t2 and energization of the first base current AIb during the period of time t2 to t3 are one cycle (period of time t1 to t3). Repeated energization.
On the other hand, the second arc is energized with the second peak current BIp during the first energization period of the first peak current AIp during the period from time t1 to t2, and the second arc is performed during the period from time t2 to t3. During the energization period of the first base current AIb, the second base current BIb is energized, followed by the second energization period of the first peak current AIp during the period from time t3 to t4 and during the period from time t4 to t5. During the energization period of the first base current AIb, the second base current BIb is energized, and the first energization (time t1 to t3 period) and the second energization (time t3 to t5 period). Repeatedly energize as one set.
[0047]
As described above, during the time t1 to t3 and the time t4 to t5, the current values for energizing the two arcs are substantially equal, so there is no influence on the arc generation state due to the mutual interference between the two arcs, and the current is stable. An arc is generated.
On the other hand, as described above with reference to FIG. 8, the second arc B3 through which the base current is applied is attracted to the first arc A3 through which the peak current is supplied, as described above with reference to FIG. The arc shape is deformed.
[0048]
By the way, as described above with reference to FIG. 2, in the conventional technique, the energization timing of the first peak current AIp and the first base current AIb in the first arc, the second peak current BIp and the second peak current in the second arc, and so on. The energization timing of the second base current BIb is at random. Therefore, every time the peak current flows through the first arc or the second arc, the other arc may be deformed by the mutual interference of the arcs. This will be explained with specific numerical values. When the frequency of the current flowing through the first arc is 240 [Hz], n = 2 as described above, so the frequency of the current flowing through the second arc is The frequency is 120 [Hz], which is 1/2 of the former. Accordingly, one of the arcs is deformed by the mutual interference of the arcs up to 360 times per second, which is the number of times the peak current is applied to the two arcs. Thus, in the prior art, the arc generation state becomes unstable due to frequent deformation of the arc, resulting in a large amount of spatter, frequent arc breakage, etc., resulting in poor quality of the work piece. become.
[0049]
In the first embodiment of the present invention described above, the peak current is always supplied to the first arc during the period in which the peak current is supplied to the second arc (time t1 to t2). Shape deformation does not occur. Further, during a period (time t3 to t4) in which the peak current is supplied to the first arc and the base current is supplied to the second arc, the second arc is deformed by the mutual interference of the arcs. However, the frequency at which such arc shape deformation occurs is reduced to 1/3 compared to the case of the prior art. In the case of the above specific numerical values, in Embodiment 1 of the present invention, the arc shape is deformed 120 times per second, which is reduced to 1/3 compared to the maximum 360 times in the prior art. To do. For this reason, in Embodiment 1 of the present invention, the amount of spatter generated is reduced and the number of occurrences of arc breakage is also reduced as compared with the prior art, so that good welding quality can be obtained.
[0050]
[Second Embodiment]
FIG. 10 is a current / voltage waveform diagram showing a multi-electrode pulse arc welding control method according to a second embodiment (hereinafter referred to as a second embodiment) corresponding to claim 3 at the time of filing. FIG. 4A shows the change over time of the first welding current AIw, FIG. 4B shows the change over time of the first welding voltage AVw, and FIG. 4C shows the second welding. The time change of the current BIw is shown, and FIG. 4D shows the time change of the second welding voltage BVw. This figure exemplifies the case where the magnification n = 3, and the second pulse period BTf of the second welding current BIw shown in FIG. 10C is the first welding current shown in FIG. This is three times the first pulse period ATf of AIw. In the figure, the operation in the period from time t1 to t5 is the same as the period from time t1 to t5 in FIG. 9, and the operation in the period from time t5 to t7 in FIG. 9 is the same as the period from time t3 to t5 in FIG. Therefore, explanation is omitted.
[0051]
Further, when the magnification n is 4 in the above, the same energization is performed three times after the time t1 to t5 in FIG. 9 after the time t1 to t5. Further, when magnification = n (n> 3), energization similar to that in the time t3 to t5 is performed n-2 times after the time t1 to t5.
[0052]
In the second embodiment of the present invention described above, the peak current is always supplied to the first arc during the period in which the peak current is supplied to the second arc (time t1 to t2). Shape deformation does not occur. Further, during the period in which the peak current is supplied to the first arc and the base current is supplied to the second arc (time t3 to t4 and time t5 to t6), the second arc is deformed by the mutual interference of the arcs. To do. However, the frequency with which the arc shape is deformed in the second embodiment of the present invention is reduced compared to the case of the prior art. For this reason, in the second embodiment of the present invention, the amount of spatter generated is reduced and the number of occurrences of arc breaks is also reduced as compared with the prior art, so that good welding quality can be obtained.
[0053]
FIG. 11 is a block diagram of a welding apparatus for carrying out the multi-electrode pulse arc welding control method of the first and second embodiments described above with reference to FIGS. 9 and 10. In the figure, the same reference numerals are given to the same circuit blocks as those of the welding apparatus described above with reference to FIG. 3, and the description thereof will be omitted. Hereinafter, the magnification setting circuit NS, the cycle conversion circuit TC, the second switching circuit BSW, and the feeding speed adjustment circuit WB of the second welding power supply apparatus BPS, which are circuit blocks different from those shown in FIG.
[0054]
The magnification setting circuit NS outputs a magnification setting signal n which is an integer of 2 (in the first embodiment) or 3 or more (in the second embodiment). The period conversion circuit TC receives the first pulse period signal ATf output from the modulation circuit MC of the first welding power supply device APS and the magnification setting signal n as described above, and synchronizes with the signal as described above. The signal is converted into a signal having a cycle that is n times that of the signal and output as a second pulse cycle signal BTf. In FIG. 9, the magnification setting signal n is 2 and in FIG. 10, the magnification setting signal n is 3.
[0055]
The second switching circuit BSW is connected to the a side when the second pulse cycle signal BTf is at the High level, and outputs the second peak current setting signal BIp as the second current control setting signal BIsc. When the signal BTf is at the low level, the second base current setting signal BIb is output as the second current control setting signal BIsc by being connected to the b side. The feed speed adjusting circuit WB receives the first feed speed setting signal AWs described above with reference to FIG. 3 and finely adjusts the value obtained by dividing the value by the magnification n as a center value. A setting signal BWs is output.
[0056]
In the above-described welding apparatus, the feeding speed of the second welding wire B1 can be adjusted to 1 / n times the feeding speed of the first welding wire A1 by setting the magnification n described above. The second welding power supply device BPS can output a welding voltage corresponding to the feeding speed by voltage feedback control using the second pulse period signal BTf. That is, in the present invention, the feeding speed of one welding wire can be adjusted to 1 / n times the other. Therefore, since the freedom degree of selection of the welding conditions in welding construction expands, the application range of the welding method of this invention expands.
[0057]
In the present invention, the voltage feedback control of the second welding power source device BPS is performed based on the voltage feedback control of the first welding power source device APS. Conversely, the voltage feedback control of the first welding power supply device APS may be performed based on the voltage feedback control of the second welding power supply device BPS.
[0058]
FIG. 12 is a comparison diagram of the number of arc breaks showing the effect of the present invention. Using the conventional welding apparatus shown in FIG. 3 and the welding apparatus of the present invention (Embodiment 1) shown in FIG. 11, the number of occurrences of arc breakage occurring during welding was compared. The figure shows the case where the magnification n = 2. The main welding conditions at this time are as follows. In other words, the first welding current AIw is 400 [A], the first welding voltage AVw is 32 [V], while the second welding current BIw is 200 [A], and the second welding current AVw is 200 [A]. The voltage BVw is 28 [V]. In the test method, welding with a welding speed of 5 [m / min] and a bead length of 50 [cm] was repeated 10 times, and the number of arc breaks per welding was counted and compared.
[0059]
As shown in the figure, in the prior art, arc breakage occurred 18 times per welding, and as a result, many spatters were generated, resulting in a poor bead appearance. On the other hand, in the present invention, the arc break occurred only twice and the frequency was low, so that good welding quality was obtained.
[0060]
【The invention's effect】
In the multi-electrode pulse arc welding method, the instability of the arc generation state such as the deformation of the arc shape and the fluctuation of the arc length caused by the mutual interference of the two arcs can be suppressed, and the welding quality is always good. Can be obtained.
Further, according to the present invention, the feeding speed of one welding wire can be adjusted to 1 / n times the feeding speed of the other welding wire, and the optimum welding voltage for the feeding speed is voltage feedback controlled. Therefore, it can be used for welding under various conditions while having the above effects.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a multi-electrode pulse arc welding apparatus.
FIG. 2 is a current / voltage waveform diagram of the prior art.
FIG. 3 is a block diagram of a conventional apparatus.
FIG. 4 is a schematic diagram of an arc generating portion for explaining a force acting on an arc generated independently.
FIG. 5 is a current / voltage waveform diagram of the prior art.
FIG. 6 is a schematic diagram of an arc generating portion when a peak current is applied to both arcs.
FIG. 7 is a schematic diagram of an arc generating part when base current is applied to both arcs.
FIG. 8 is a schematic diagram of an arc generating portion when a peak current is applied to a first arc and a base current is applied to a second arc.
FIG. 9 is a current / voltage waveform diagram according to the first embodiment of the present invention;
FIG. 10 is a current / voltage waveform diagram according to the second embodiment of the present invention.
FIG. 11 is a block diagram of the welding apparatus of the present invention.
FIG. 12 is a comparison diagram of the number of arc break occurrences showing the effect of the present invention.
[Explanation of symbols]
1 Welding wire
2 Workpiece
21 molten pool
3 Arc
4 Welding torch
A1 first welding wire
A3 First arc
A41 First contact chip
AFZ, BFZ Force by magnetic field
AIB first base current setting circuit
AIb first base current, first base current setting signal
AIP first peak current setting circuit
AIp first peak current, first peak current setting signal
AIsc first current control setting signal
AIw 1st welding current
APS first welding power source
ASW first switching circuit
ATf first pulse period, first pulse period signal
ATp First peak current conduction time
AVb first base voltage
AVp first peak voltage
AVS first voltage setting circuit
AVs first voltage setting signal
AVw 1st welding voltage
AWF first wire feeder
AWS First feed speed setting circuit
AWs First feed speed setting signal
B1 Second welding wire
B3 Second arc
B41 Second contact chip
BIB second base current setting circuit
BIb second base current, second base current setting signal
BIP second peak current setting circuit
BIp second peak current, second peak current setting signal
BIsc second current control setting signal
BIw Second welding current
BPS second welding power supply
BSW second switching circuit
BTf Second pulse period, second pulse period signal
BTp Second peak current conduction time
BVb second base voltage
BVp second peak voltage
BVS second voltage setting circuit
BVs Second voltage setting signal
BVw Second welding voltage
BWF Second wire feeder
BWS Second feed speed setting circuit
BWs Second feed speed setting signal
EI current error amplifier circuit
Ei Current error amplification signal
EV voltage error amplifier circuit
Ev Voltage error amplification signal
FX, AFX, BFX Arc contraction force
FY, BFY Force by magnetic field
ID current detection circuit
Id Current detection signal
INV output control circuit
Iw welding current
MC modulation circuit
MM mono multivibrator
NS magnification setting circuit
n Magnification, magnification setting signal
TC period conversion circuit
TP peak current conduction time setting circuit
Tp Peak current conduction time setting signal
VD voltage detection circuit
Vd Voltage detection signal
VF V / F conversion circuit
Vf V / F conversion signal
WB feed speed adjustment circuit
WC feed control circuit
Wc Feed control signal

Claims (5)

A first welding wire and a second welding wire, which are electrically insulated from each other from one welding torch, are fed at a preset feeding speed, respectively, and a first preset wire is supplied to the first welding wire. The energization of the peak current and the energization of the first base current set in advance are repeated as one cycle, and the energization of the second peak current set in advance and the second preset in the second welding wire are repeated. Multi-electrode pulse arc welding in which energization with a base current of 1 cycle is repeated and two arcs are generated between the first welding wire and the second welding wire and the work piece to be welded In the control method,
The second welding wire is energized with the second peak current during the first energization period of the first peak current, and is energized with the second base current during the energization period of the first base current. Subsequently, during the second energization period of the first peak current and the energization period of the first base current, the second base current is energized, and the first and second energizations are performed in one set. As a multi-electrode pulse arc welding control method to energize repeatedly. 2. The multi-electrode pulse arc welding control method according to claim 1, wherein the feeding speed of the second welding wire is a value obtained by further finely adjusting a value obtained by halving a preset feeding speed of the first welding wire. A first welding wire and a second welding wire, which are electrically insulated from each other from one welding torch, are fed at a preset feeding speed, respectively, and a first preset wire is supplied to the first welding wire. The energization of the peak current and the energization of the first base current set in advance are repeated as one cycle, and the energization of the second peak current set in advance and the second preset in the second welding wire are repeated. Multi-electrode pulse arc welding in which energization with a base current of 1 cycle is repeated and two arcs are generated between the first welding wire and the second welding wire and the work piece to be welded In the control method,
The second welding wire is energized with the second peak current during the first energization period of the first peak current, and is energized with the second base current during the energization period of the first base current. Subsequently, in the second energization period of the first peak current and the energization period of the first base current, the second base current is energized, and the same energization as in the second time is preset. A multi-electrode pulse arc welding control method in which energization is repeated until the n-th time which is an integer of 3 or more and the first to n-th energizations are repeated as one set. 4. The multi-electrode pulse arc welding control method according to claim 3, wherein the feeding speed of the second welding wire is a value obtained by further finely adjusting a value obtained by multiplying a preset feeding speed of the first welding wire by 1 / n. The length of one cycle of energization of the first peak current energizing the first welding wire and energization of the first base current detects the welding voltage between the first welding wire and the workpiece. The multi-electrode pulse arc welding control method according to claim 1, 2, 3, or 4, which is determined by frequency modulation control or pulse width modulation control based on an error between the detected voltage detection signal and a preset voltage setting signal.

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