JP4312999B2 - Arc start control method. - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arc start control method for consumable electrode arc welding in which a welding wire is fed to an object to be welded by a wire feed motor to start the arc.
[0002]
[Prior art]
FIG. 6 is a block diagram of a welding power source apparatus that implements a conventional arc start control method. Hereinafter, each circuit block will be described with reference to FIG.
[0003]
The welding wire 1 is fed through the welding torch 4 by a feeding roll 5 directly connected to the wire feeding motor WM. The welding voltage Vw from the welding power source device PS is fed to the welding wire 1 by a contact tip 4a (not shown) attached to the tip of the welding torch 4.
[0004]
The output current detection circuit ID detects the welding current Iw and outputs an output current detection signal Id. The output voltage detection circuit VD detects the welding voltage Vw and outputs an output voltage detection signal Vd.
[0005]
The short-circuit detection circuit SA receives the output voltage detection signal Vd as an input, detects contact between the welding wire 1 and the workpiece 2 and outputs the short-circuit detection signal Sa at a high level in the contact state.
[0006]
The steady feeding speed setting circuit WS outputs a steady feeding speed setting value Ws. When a welding start signal St is input from the outside, the feed control circuit FC outputs a feed control signal Fc corresponding to a predetermined initial feed speed setting value Wi to the workpiece 2 from the welding wire 1, Subsequently, when the short circuit detection signal Sa becomes High level, it is determined that the welding wire 1 has contacted the workpiece 2 and the output of the feed control signal Fc is stopped, and then the short circuit detection signal Sa is When the high level is changed to the low level, it is determined that the contact between the welding wire 1 and the workpiece 2 is released, and the feed control signal Fc corresponding to the steady feed speed set value Ws is output.
[0007]
The voltage setting circuit VS outputs a voltage setting value Vs. The output control circuit SC starts operation when an external welding start signal St is input, and outputs an output control signal Sc corresponding to the initial short-circuit current set value Is while the short-circuit detection signal Sa is at a high level. During the period when the short circuit detection signal Sa is at the low level, the output control signal Sc corresponding to the steady welding current set value Ii is output.
[0008]
The welding power source main circuit INV receives a commercial power source and outputs a welding voltage Vw and a welding current Iw suitable for stabilizing the arc 3 by inverter control, thyristor phase control, or the like. This welding power source main circuit INV forms a constant current characteristic or a drooping characteristic in which an initial short circuit current is passed during a period in which the short circuit detection signal Sa is at a high level, and a steady welding current in a period in which the short circuit detection signal Sa is at a low level. And a constant voltage characteristic corresponding to the voltage set value Vs is formed.
[0009]
FIG. 7 is a waveform diagram for explaining the operation of the welding power source apparatus shown in FIG. 7A shows the time change of the welding start signal St, FIG. 7B shows the time change of the welding voltage Vw, FIG. 7C shows the time change of the welding current Iw, and FIG. ) Shows the time change of the short circuit detection signal Sa, FIG. 7 (E) shows the time change of the feed control signal Fc, FIG. 7 (F) shows the time change of the wire tip / workpiece distance Lw, S1 to S5 in the figure show the feeding state of the welding wire 1 at each time. Hereinafter, a description will be given with reference to FIG.
[0010]
When the welding start signal St is input from the outside at time t = t1 shown in FIG. 7A, a feed control signal Fc corresponding to the initial feed speed setting value Wi shown in FIG. As shown in FIG. 7 (S1), feeding of the welding wire 1 to the workpiece 2 is started. At the same time, the no-load voltage of the welding power source main circuit INV is applied as the welding voltage Vw shown in FIG. Next, during the period from the time t1 to the time t2, the welding wire 1 is fed at a speed corresponding to the initial feed speed setting value Wi, and as shown in FIG. The distance Lw is gradually shortened.
[0011]
At time t = t2 shown in FIG. 7A, when the welding wire 1 comes into contact with the work piece 2 as shown in FIG. 7S2, the short circuit detection signal Sa is changed as shown in FIG. From Low level to High level. When this short circuit detection signal Sa becomes High level, the output of the feed control signal Fc shown in FIG. 7E is stopped and the feed of the welding wire 1 is stopped. At the same time, the welding current Iw shown in FIG. 7C is energized as a large initial short circuit current. Next, during the period from time t2 to t3, the initial short-circuit current is energized while the feeding of the welding wire 1 is stopped.
[0012]
At time t = t3 shown in FIG. 7 (A), as shown in FIG. 7 (S3), the tip of the welding wire 1 is melted by energizing the initial short-circuit current to generate an arc 3b. At this time, burning occurs, and the wire tip-to-be-welded distance Lw shown in FIG. 7 (F) becomes longer and the welding voltage Vw shown in FIG. 7 (B) also becomes higher. Next, when the arc 3b is generated, the short-circuit detection signal Sa becomes a low level. When the short-circuit detection signal Sa becomes a low level, the welding wire 1 is fed at a speed corresponding to the steady feeding speed set value Ws. Be paid.
[0013]
At time t = t4 shown in FIG. 7A, the welding wire 1 is fed at a speed corresponding to the steady feeding speed set value Ws, and the welding power source main circuit INV forms a constant voltage characteristic and is steady. A welding current corresponding to the welding current value Ii is applied.
[0014]
[Problems to be solved by the invention]
In consumable electrode arc welding in which a welding wire (soft aluminum wire) is fed to the workpiece and arc-started, if a long-term short-circuit occurs (short-circuit period of 100 ms or more) at the start of the arc, the welding wire is energized with an initial short-circuit current. As a result, the tip of the welding wire is melted and an arc is generated. At this time, the welding wire is rapidly burned up by energization of a large initial short-circuit current, so that the arc length becomes very long. Due to the change in the arc length at the time of the arc start, it takes time to shift to the arc length of the steady arc. For this reason, there is a problem that the appearance of the weld bead at the time of the arc start is deteriorated.
[0015]
[Means for Solving the Problems]
According to a first aspect of the present invention, when a welding start signal is input to the welding power source device, the welding wire is fed to the work piece and the output of the welding power source device is started. When the contact with the object is detected, the feeding of the welding wire is stopped and a predetermined initial short-circuit current is supplied from the welding power source, and the tip of the welding wire is melted by the supply of the initial short-circuit current. The consumable electrode arc that starts feeding the welding wire to the workpiece at a predetermined steady feeding speed from the time when the arc is generated and supplies a steady welding current corresponding to the steady feeding speed. In the welding arc start control method, the arc is generated when the contact period between the welding wire and the workpiece is calculated and the length of the contact period is equal to or longer than a predetermined reference contact period. A continuation stop of the welding wire from the point in time and a transition to a predetermined flaming suppression current lower than the initial short-circuit current to provide a flaming suppression period for continuing the arc for a predetermined period, When finished, the welding wire is fed again to the workpiece at the steady feeding speed, the burnup suppression current is shifted to the steady welding current, and the calculated length of the contact period is the reference contact. When the period is less than the period, starting to feed the welding wire to the workpiece again at the steady feeding speed from the time when the arc is generated, and shifting the initial short circuit current to the steady welding current. An arc start control method is characterized.
[0016]
The second invention is the arc start control method according to claim 1, wherein the burn-up suppression period is automatically set according to the length of the contact period.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a welding power source apparatus that implements the arc start control method of the present invention. In the figure, the same reference numerals as those in the block diagram of the prior art power supply apparatus shown in FIG.
[0019]
The burn-up suppression calculation circuit CT determines the contact state between the welding wire 1 and the workpiece 2 according to the short circuit detection signal Sa, and when the short circuit detection signal Sa changes from the High level to the Low level, the tip of the welding wire 1 is detected. Is burned out from the work piece 2, and a burn-up suppression calculation signal Ct for a predetermined period is output.
[0020]
When the welding start signal St is input from the outside, the fuel consumption suppression-corresponding feed control circuit FCS outputs a fuel rise restraint-corresponding feed control signal Fcs corresponding to a predetermined initial feed speed setting value Wi, and continues. During the period when the short-circuit detection signal Sa is at a high level, the output of the fuel supply control signal Fcs for suppressing the increase in fuel is stopped, and subsequently, during the period when the increase control signal Ct is at a high level, the above-described increase in fuel suppression is supported. The stop of the feed control signal Fcs is maintained. Subsequently, when the short-circuit detection signal Sa and the fuel up suppression control signal Ct are at a low level, the fuel up suppression compatible feeding control signal Fcs corresponding to the steady feeding speed set value Ws is output.
[0021]
The burn-up suppression corresponding output control signal SCS starts operation when an external welding start signal St is input, and selects the initial short-circuit current set value Is while only the short-circuit detection signal Sa is at the high level. An output control signal Sc corresponding to the initial short-circuit current set value Is is output, and during the period when only the above-described fuel up suppression control signal Ct is at a high level, the fuel up suppression current setting signal Il is selected, and the above fuel up suppression current setting signal is selected. The output control signal Sc corresponding to Il is output, the steady welding current set value Ii is selected while the short circuit detection signal Sa and the burnup suppression calculation signal Ct are at the low level, and the steady welding current set value is selected. An output control signal Sc corresponding to Ii is output.
[0022]
FIG. 2 is a waveform diagram for explaining the operation of the welding power source apparatus shown in FIG. 2A shows the time change of the welding start signal St, FIG. 2B shows the time change of the welding voltage Vw, FIG. 2C shows the time change of the welding current Iw, and FIG. ) Shows the time change of the short circuit detection signal Sa, FIG. 2 (E) shows the time change of the burnup suppression calculation signal Ct, and FIG. 2 (F) shows the time change of the fuel supply control signal Fcs corresponding to the burnup suppression. FIG. 2 (G) shows the change over time in the distance Lw between the wire tip and the workpiece, and S1 to S5 in FIG. 2 show the feeding state of the welding wire 1 at each time. Hereinafter, a description will be given with reference to FIG.
[0023]
When a welding start signal St is input from the outside at time t = t1 shown in FIG. 2 (A), a fuel supply control signal corresponding to the fuel upregulation corresponding to the initial feed speed setting value Wi shown in FIG. 2 (F). Fcs is output, and as shown in FIG. 2 (S1), feeding of the welding wire 1 to the workpiece 2 is started. At the same time, the no-load voltage of the welding power source main circuit INV is applied as the welding voltage Vw shown in FIG. Next, during the period from the time t1 to the time t2, the welding wire 1 is fed at a speed according to the initial feed speed setting value Wi, and as shown in FIG. The distance Lw is gradually shortened.
[0024]
At time t = t2 shown in FIG. 2 (A), when the welding wire 1 contacts the work piece 2 as shown in FIG. 2 (S2), as shown in FIG. From Low level to High level. When the short-circuit detection signal Sa becomes High level, the output of the fuel suppression control feeding control signal Fcs shown in FIG. 2 (F) is stopped and the feeding of the welding wire 1 is stopped. At the same time, the welding current Iw shown in FIG. 2C is energized as a large initial short circuit current. Next, during the period from time t2 to t3, the initial short-circuit current is energized while the feeding of the welding wire 1 is stopped.
[0025]
At time t = t3 shown in FIG. 2 (A), as shown in FIG. 2 (S3), the distal end portion of the welding wire 1 is melted by the energization of the initial short-circuit current to generate an arc 3a. At this time, the burn-up suppression calculation circuit CT determines that the short-circuit detection signal Sa of the input signal has changed from the High level to the Low level and the tip of the welding wire 1 has been melted from the work piece 2, and FIG. The burn-up suppression calculation signal Ct for the predetermined period shown is output at a high level. During the fuel up suppression period in which the fuel up suppression calculation signal Ct is at a high level, the feeding of the welding wire 1 is stopped and a welding current Iw corresponding to a predetermined small current fuel up suppression current setting signal Il is output. Then, the burn-up of the welding wire 1 is suppressed to prevent the distance Lw between the wire tip and the workpiece to be welded shown in FIG.
[0026]
At time t = t4 shown in FIG. 2 (A), when the fuel up suppression control signal Ct and the short circuit detection signal Sa become low level, the fuel up suppression compatible feed control circuit FCS sets the steady feed speed set value. The welding wire 1 is fed at a speed feeding according to Ws, and the output control signal SCS corresponding to the burnup suppression outputs an output control signal Sc corresponding to the steady welding current set value Ii. Next, during the period from time t4 to time t5, the contact power supply main circuit INV forms a constant voltage characteristic and energizes a welding current according to a steady welding current signal Ii.
[0027]
[Example 2]
FIG. 3 is a block diagram of a welding power source apparatus according to a second embodiment that implements the arc start control method of the present invention. In this figure, the same reference numerals as those in the block diagrams of the power supply apparatus shown in FIGS. 1 and 6 perform the same operations, and thus the description thereof will be omitted and different operations will be described.
[0028]
The reference contact time setting circuit TR outputs a reference contact time setting value Tr.
[0029]
The burn-up suppression calculation comparison circuit CTC calculates the contact period T2 shown in FIG. 2B, and calculates the calculated contact period T2 and the reference contact time setting value Tr set by the reference contact time setting circuit TR. In comparison, when the calculated contact period T2 is equal to or longer than the reference contact period Tr, a fuel up suppression calculation comparison signal Ctc for a predetermined fuel up suppression period T3 is output.
[0030]
During the output period of the burnup suppression calculation comparison signal Ctc, the welding current Iw corresponding to the small current burnup suppression current signal Il is output in advance while the feeding of the welding wire 1 is stopped. Suppression of burning is prevented, and the distance Lw between the wire tip and the workpiece is prevented from becoming long.
[0031]
When the calculated contact time T2 is less than a predetermined reference contact period setting signal Tr, the feeding to the workpiece 1 is started by switching to a predetermined steady feeding speed Ws when an arc is generated. In addition, a steady welding current Ii corresponding to the steady feeding speed Ws is applied.
[0032]
[Example 3]
The third embodiment has the same configuration as the block diagram of the welding power source apparatus of the second embodiment, and the difference is that the burnup suppression period T3 is automatically set based on the relationship diagram between the contact period and the burnup suppression time shown in FIG. is there.
[0033]
The burn-up suppression calculation comparison circuit CTC calculates the contact period T2 by comparing the calculated contact period T2 with the reference contact time setting value Tr set by the reference contact time setting circuit TR. When the contact period T2 is equal to or longer than the reference contact period Tr, the burnup suppression period T3 of the burnup suppression calculation comparison signal Ctc is automatically calculated and output from the relational expression between the contact period and the burnup suppression time shown in FIG.
[0034]
FIG. 5 shows the method of Example 3 described above, using a soft aluminum wire with a welding wire of 1.2 [mm], setting the welding current to 100 [A], the welding voltage to 17 [V], and starting welding at 100. It is a welding voltage rise comparison figure which measured the frequency | count that the welding voltage at the time of starting was 3 [V] or more higher than the steady welding voltage 17 [V].
[0035]
【The invention's effect】
When a long-term short circuit occurs at the start of the arc, the welding wire is melted at the tip of the welding wire by the initial short-circuit current, and an arc is generated. When this arc occurs, a predetermined burnup suppression period is provided, and welding is performed by supplying a predetermined small current rise suppression current while stopping the feeding of the welding wire during the burnup suppression period. Suppresses the burn-up of the wire and prevents the arc length at the start of arc from becoming long. As a result, the weld bead appearance at the arc start portion is improved.
[Brief description of the drawings]
FIG. 1 is a block diagram of a welding power source apparatus for implementing an arc start control method of the present invention.
FIG. 2 is a waveform diagram for explaining the operation of the welding power source device shown in FIG. 1;
FIG. 3 is a block diagram of a welding power source apparatus according to a second embodiment that implements the arc start control method of the present invention.
FIG. 4 is a relationship diagram between a short-circuit period and a burn-up suppression period.
FIG. 5 is a comparison diagram of the welding voltage rise at the start showing the effect of the present invention.
FIG. 6 is a block diagram of a welding power source apparatus that implements a conventional arc start control method.
7 is a waveform diagram for explaining the operation of the welding power source apparatus shown in FIG. 5. FIG.
[Explanation of symbols]
1 Welding Wire 2 Workpiece 3 Arc 3a Initial Arc of the Present Invention
3b Conventional initial arc (occurrence state)
3c Steady arc (occurrence state)
4 Welding torch 4a Contact tip 5 Feeding roll CT of wire feeding device Burnup suppression calculation circuit CTC Burnup suppression calculation comparison circuit FC Feeding control circuit FCS Feeding control circuit ID corresponding to burnup suppression Output current detection circuit INV Welding power supply Main circuit PS Welding power supply device PSC Welding power suppression compatible welding power supply device TR Standard contact time setting circuit SA Short-circuit detection circuit SC Output control circuit SCS Output control circuit VD for fuel suppression control Output voltage detection circuit VS Voltage setting circuit WS Regular transmission Feed speed setting circuit WM Wire feed motor Ct Burnup suppression calculation signal Ctc Burnup suppression calculation comparison signal Fc Feed control signal Fcs Feed control signal Id corresponding to burnup suppression Output current detection signal Ii Steady welding current (value / setting) value)
Il Burnup suppression current (value / setting value)
Is Initial short circuit current (value / setting value)
Iw Welding current Lw Distance between wire tip and work piece Sa Short circuit detection signal Sc Output control signal St Welding start signal Tr Reference contact time (value / setting value)
Vd Output voltage detection signal Vs Voltage set value Vw Welding voltage Wi Initial feed speed set value Ws Steady feed speed set value T1 Slow down period T2 Contact period T3 Burnup suppression period

Claims (2)

When a welding start signal is input to the welding power source device, the welding wire is fed to the workpiece and the output of the welding power source device is started, and the welding wire and the workpiece are brought into contact by the feeding. When the welding wire is stopped, the welding power supply device is stopped and a predetermined initial short-circuit current is supplied from the welding power source. When the initial short-circuit current is supplied, the tip of the welding wire is melted and an arc is generated . The arc start control method for consumable electrode arc welding that starts feeding the welding wire from the workpiece to the workpiece at a predetermined steady feeding speed and energizes a steady welding current corresponding to the steady feeding speed. In the above, the contact period between the welding wire and the workpiece is calculated, and when the length of the contact period is equal to or longer than a predetermined reference contact period, A continuation stop of the contact wire and a transition to a predetermined flaming suppression current lower than the initial short-circuit current are provided to provide a flaming suppression period for continuing the arc for a predetermined period. The welding wire is fed again to the workpiece at the steady feeding speed, the burnup suppression current is shifted to the steady welding current, and the calculated length of the contact period is less than the reference contact period. When the arc is generated, the welding wire is again fed to the workpiece at the steady feeding speed, and the initial short circuit current is shifted to the steady welding current. Arc start control method.   The arc start control method according to claim 1, wherein the burn-up suppression period is automatically set according to the length of the contact period.

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