JP2016147268A - Two-wire welding control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably keep a molten state of a filler wire, even when a distance between a power supply tip and a base material is varied, in a 2-wire welding method using a consumable electrode and the filler wire.SOLUTION: In a 2-wire welding control method, welding voltage Vav is impressed between a consumable electrode to which power is supplied from a power supply tip and a base material, an arc is generated to form a molten pool, and welding is performed while feeding a filler wire having an angle of advance to a rear part of the molten pool. In the method, variation in a distance Lt between the power supply tip and the base material during welding is detected, and at least one of the welding voltage Vav, a feed speed Fw of the filler wire or an inter-wire distance Lwr between the consumable electrode and the filler wire, is feed-back controlled according to the variation in the distance Lt between the power supply tip and the base material. Thus, since a variation in heat gain to the filler wire accompanied with the variation in the distance Lt between the power supply tip and the base material can be compensated, a molten state can be stably kept.SELECTED DRAWING: Figure 1

Description

  The present invention applies a welding voltage between a consumable electrode fed from a power supply tip and a base material to generate an arc to form a molten pool, and a filler wire having an advancing angle is provided at the rear of the molten pool The present invention relates to a two-wire welding control method for welding while feeding.

  A two-wire welding method in which an arc is generated between a consumable electrode (hereinafter referred to as a welding wire) and a base material to form a molten pool, and a filler wire is fed to the molten pool for welding (see Patent Document 1). ) Is conventionally known. In this two-wire welding method, since the molten metal of the filler wire is added to the molten metal of the welding wire, the amount of the molten metal is increased, and high-speed and high-efficiency welding is possible. In particular, when high-speed welding is performed by the two-wire welding method, it is important to feed the filler wire by short-circuiting it from the rear side of the consumable electrode arc to the molten pool in order to prevent a humping bead. This is because when the filler wire is fed into the consumable electrode arc and melted, the molten pool is hardly cooled and the swell of the latter half of the molten pool cannot be suppressed by the filler wire, thereby suppressing the humping bead. This is because there is no effect. On the other hand, if the filler wire is short-circuited to the rear part of the molten pool at the peripheral edge of the arc and fed and melted by the heat of the molten pool, the molten pool is cooled, and the latter part of the molten pool is filled by the filler wire. Is suppressed, and the formation of a humping bead can be suppressed. Therefore, in the two-wire welding method of the prior art, the molten pool is cooled by short-circuiting the filler wire in a cold state without passing a current through the filler wire.

  In the two-wire welding method, various consumable electrodes such as a carbon dioxide arc welding method, a mag welding method, a MIG welding method, a pulse arc welding method, and an AC arc welding method are used as a method for generating an arc between the welding wire and the base material. A type arc welding process can be used. Further, the filler wire basically has a wire tip short-circuited with the molten pool, and is melted by heat from the molten pool. Therefore, no arc is generated between the filler wire and the molten pool. In this invention, although the case where a pulse arc welding method is used as said consumable electrode type arc welding method is demonstrated, another welding method may be sufficient. Moreover, in the following description, the base material and the molten pool are used in substantially the same meaning.

  FIG. 5 is a current / voltage waveform diagram in the two-wire welding method using pulse arc welding. The figure (A) shows the time change of the welding current Iw which energizes a welding wire, the figure (B) shows the time change of the welding voltage Vw applied between a welding wire and a base material (molten pool), FIG. 5C shows the change over time of the filler wire feed speed Fw. Although the welding wire feeding speed is not shown, it is constantly fed at a predetermined value. No voltage is applied between the filler wire and the molten pool, and no current is applied. As described above, the filler wire is fed in a state of being short-circuited with the molten pool. Even if the filler wire is separated from the molten pool, no voltage is applied, so no arc is generated between the filler wire and the molten pool. Hereinafter, a description will be given with reference to FIG.

  During the peak period Tp from time t1 to t2, a peak current Ip having a large current value equal to or higher than the critical value is energized to transfer droplets from the welding wire as shown in FIG. ), A peak voltage Vp proportional to the arc length is applied between the welding wire and the molten pool.

  During the base period Tb from time t2 to t3, as shown in FIG. 5A, the base current Ib having a small current value less than the critical value is energized in order to prevent the formation of droplets. ), The base voltage Vb is applied. Welding is performed by repeating the period from time t1 to t3 as one period (pulse period Tf).

  As shown in FIG. 5C, the filler wire feed speed Fw is a constant value, and is set to a feed speed that is stably melted by heat input from the melted ground in a short-circuited state with the melted ground. The filler wire feeding speed Fw is often set to a range of about 20 to 30% of the welding wire feeding speed.

  By the way, in order to perform good pulse arc welding, it is important to maintain the arc length at an appropriate value. In order to maintain the arc length at an appropriate value, the following output control (arc length control) of the welding power source is performed. The arc length is substantially proportional to the average welding voltage Vav indicated by a broken line in FIG. For this purpose, output control is performed to detect the average welding voltage Vav and change the average welding current Iav indicated by the broken line in FIG. 5A so that the detected value becomes equal to the welding voltage set value corresponding to the appropriate arc length. Do. When the average welding voltage Vav is larger than the welding voltage set value, it is when the arc length is longer than the appropriate value. Therefore, the average welding current Iav is decreased to decrease the wire melting rate and shorten the arc length. On the other hand, when the average welding voltage Vav is smaller than the welding voltage set value, the arc length is shorter than the appropriate value, so that the average welding current Iav is increased to increase the wire melting rate and the arc length is increased. To do. As the average welding voltage Vav, a value obtained by passing the welding voltage Vw through a low-pass filter (cutoff frequency of about 1 to 10 Hz) is generally used. Further, as an operation amount for changing the average welding current Iav, at least one of the peak period Tp, the pulse period Tf, the peak current Ip, or the base current Ib is changed. For example, when feedback control is performed using the pulse period Tf as an operation amount, the peak period Tp, the peak current Ip, and the base current Ib are set to predetermined values (referred to as a frequency modulation control method). When feedback control is performed using the peak period (pulse width) Tp as an operation amount, the peak current Ip, the base current Ib, and the pulse period Tf are set to predetermined values (referred to as a pulse width modulation control method). When the welding wire is a steel material having a diameter of 1.2 mm, Ip = 450 A, Ib = 50 A, and Tp = 1.2 ms are set. In this case, a steel wire having a diameter of 1.2 mm is often used as the filler wire.

  In the two-wire welding method shown in Patent Document 2, one of characteristics such as a feeding speed, feeding resistance, and vibration generated by feeding the filler wire is detected and applied to the feeding speed of the filler wire or the filler wire. Control the current for preheating. For this reason, it is possible to prevent welding defects caused by filler wire unmelted due to fluctuations in welding conditions due to disturbances or missetting of welding conditions while limiting the amount of heat input to the base metal or maintaining the welding amount and leg length. It is stated that it can be done.

  FIG. 6 shows a welding torch tip for explaining that the distance Lw between the welding wire 1 and the filler wire 6 changes when the distance Lt between the power feed tip and the base material changes in the two-wire welding method. FIG. FIG. 4A shows the case where the distance Lt = Lt1 between the power supply tip and the base material is a set value, and FIG. 4B shows the case where the distance Lt = Lt2 between the power supply chip and the base material becomes shorter than the set value. FIG. 6C shows the case where the distance Lt = Lt3 between the power feed tip and the base material is longer than the set value. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 5A, welding proceeds in the left direction. The welding wire 1 is fed to the base material 2 from the power feed tip 41 in the welding torch 4 and the arc 3 is generated. A melted ground 21 is formed by the arc 3. The filler wire 6 is fed in a short-circuited state on the melted ground 21 behind the welding wire 1. The filler wire guide 7 is fixed to the welding torch 4, and the filler wire 6 is fed from the filler wire guide 7. The filler wire 6 has an advancing angle and is fed obliquely from the rear. The advance angle is set to about 35 degrees. In FIG. 6A, the distance between the power feed tip and the base material is a set value of Lt1 [mm]. Lt1 is set to about 15 mm. The distance between the position P1 where the feeding direction of the welding wire 1 intersects the surface of the base material 2 and the position P2 where the filler wire 6 is short-circuited to the base material 2 (melted ground 21) is the inter-wire distance Lw. In the figure (A), it is Lw1 [mm]. Lw1 is about 3 mm.

  FIG. 4B shows a case where the distance Lt between the power feed tip and the base material is shortened to Lt2 during welding. Therefore, Lt2 <Lt1. Since the filler wire guide 7 is integrated with the welding torch 4, the filler wire 6 also approaches the base material 2 side when the distance Lt between the power feed tip and the base material is shortened. As a result, the inter-wire distance Lw is Lw2, which is longer than Lw1. In other words, when the distance Lt between the power supply tip and the base material changes in the direction of shortening, the distance Lw between wires changes in the direction of increase.

  FIG. 6C shows the case where the distance Lt between the power feed tip and the base material is increased to Lt3. In this case, the inter-wire distance Lw is reduced to Lw3.

  The distance Lt between the power feed tip and the base material varies during welding due to variations in workpiece machining accuracy, workpiece fixing positions, thermal deformation of workpieces being welded, and the like. The wire-to-wire distance Lw changes according to the fluctuation of the power supply tip / base material distance Lt. As described above, since the set value of the inter-wire distance Lw is as small as about 3 mm, the inter-wire distance Lw also changes by several mm just by changing the feed tip-base material distance Lt by several mm. When the inter-wire distance Lw changes, the amount of heat input from the melted land 21 to the filler wire 6 changes, so the molten state changes. For this reason, the stable molten state collapses, and the welding quality such as the bead appearance deteriorates.

JP 2010-1647489 A JP 2002-28784 A

  Therefore, in the present invention, in the two-wire welding method, the two-wire welding control that can maintain the molten state of the filler wire stably and obtain good welding quality even if the distance between the power feed tip and the base material fluctuates during welding. It aims to provide a method.

In order to solve the above-described problems, the invention of claim 1
A welding voltage is applied between the consumable electrode fed from the power supply tip and the base material to generate an arc to form a molten pool, and a filler wire having a forward angle is fed to the rear of the molten pool In the 2-wire welding control method of welding while
Detecting a change in the distance between the power supply tip and the base material during welding, and feedback-controlling a parameter correlated with the heat input to the filler wire according to the change in the distance between the power supply tip and the base material,
This is a two-wire welding control method.

In the invention of claim 2, the parameter is at least one of the welding voltage, a feeding speed of the filler wire, or a distance between wires of the consumable electrode and the filler wire.
The two-wire welding control method according to claim 1.

The invention of claim 3 changes the parameter only when the fluctuation of the distance between the power supply tip and the base material is shorter than a predetermined reference value.
The two-wire welding control method according to claim 1.

In the invention of claim 4, the parameter is at least one of the welding voltage, a feeding speed of the filler wire, a distance between wires of the consumable electrode and the filler wire, or a welding speed.
The two-wire welding control method according to claim 3.

  According to the present invention, even if the distance between the power supply tip and the base material varies during welding and the distance between wires varies, and the heat input to the filler wire changes, the parameter correlated with the heat input is feedback controlled. Thus, the amount of heat input can be compensated. For this reason, in the present invention, in the two-wire welding method, even if the distance between the power supply tip and the base material varies during welding, the molten state of the filler wire can be kept stable and good welding quality can be obtained.

It is a timing chart which shows the 2 wire welding control method which concerns on Embodiment 1 of this invention. It is a block diagram of the welding apparatus for enforcing the 2-wire welding control method which concerns on Embodiment 1 of this invention. It is a timing chart which shows the 2 wire welding control method which concerns on Embodiment 2 of this invention. It is a block diagram of the welding apparatus for enforcing the 2-wire welding control method which concerns on Embodiment 2 of this invention. In a prior art, it is an electric current and a voltage waveform diagram in the 2 wire welding method using pulse arc welding. In the two-wire welding method, it is a schematic view of the welding torch tip for explaining that the inter-wire distance Lw between the welding wire 1 and the filler wire 6 changes when the feeding tip / base material distance Lt changes. .

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
The invention of Embodiment 1 detects a change in the distance between the power supply tip and the base material during welding, and feedback-controls a parameter correlated with the heat input to the filler wire in accordance with the change in the distance between the power supply tip and the base material. Is. The parameter is at least one of a welding voltage, a feeding speed of the filler wire, or a distance between the consumable electrode and the filler wire.

  FIG. 1 is a timing chart showing a two-wire welding control method according to Embodiment 1 of the present invention. FIG. 4A shows the time change of the distance Lt between the power feed tip and the base material, FIG. 2B shows the time change of the average welding current Iav, and FIG. 3C shows the time change of the average welding voltage Vav. (D) shows the time change of the feeding speed Fw of the filler wire, (E) shows the time change of the welding voltage setting signal Vr, and (F) shows the inter-wire distance setting signal Lwr. The time change of is shown. As described above with reference to FIG. 5, the average welding current Iav is obtained by averaging (smoothing) the pulse waveform welding current Iw, and the average welding voltage Vav is obtained by averaging (smoothing) the pulse waveform welding voltage Vw. is there. Although not shown, the welding wire feeding speed is fed at a predetermined constant value. No voltage is applied between the filler wire and the molten pool, and no current is applied. As described above, the filler wire is fed in a state where it has a forward angle and is short-circuited with the rear portion of the melted ground. Even if the filler wire is separated from the molten pool, no voltage is applied, so no arc is generated between the filler wire and the molten pool. Hereinafter, a description will be given with reference to FIG.

(1) Period in which the distance Lt between the power supply tip and the base material at time t1 to t2 is the set value Lt1 During the period from time t1 to t2, as shown in FIG. Is the set value Lt1. For this reason, the average welding current Iav is the reference current value It as shown in FIG. As shown in FIG. 5E, the welding voltage setting signal Vr is a reference voltage setting value Vtr, and as shown in FIG. 5C, the average welding voltage Vav is a reference corresponding to the reference voltage setting value Vtr. The voltage value is Vt. As shown in FIG. 4D, the filler wire feed speed Fw is the reference feed speed Ft. As shown in FIG. 5F, the inter-wire distance setting signal Lwr is a set value Lwtr. That is, by the welding operator, the distance Lt between the power supply tip and the base material is set to the set value Lt1, the distance Lw between the wires is set to the set value Lw1, the welding voltage setting signal Vr is set to the reference voltage set value Vtr, and the filler wire feed speed is set. Fw is set to the reference feed speed Ft, respectively.

(2) Period in which the distance Lt between the power supply tip and the base material at time t2 to t3 fluctuates in the direction of shortening to Lt2 During the period from time t2 to t3, as shown in FIG. A period during which the distance Lt between the base materials fluctuates and is shortened to Lt2. In response to this, the average welding current Iav increases to I2 as shown in FIG. The welding current change ΔI = I2−It, and the inter-wire distance change ΔLw = G · ΔI can be calculated. Here, G is a positive constant.

  As shown in FIG. 5E, the welding voltage setting signal Vr is increased to Vrt + ΔLw. In response to this, as shown in FIG. 5C, the average welding voltage Vav increases to a value V2 corresponding to the welding voltage setting signal Vr. Since the distance Lt between the power supply tip and the base material is shortened to Lt2, the distance Lw between the wires is increased to Lw2, and the heat input to the filler wire is reduced because the distance from the arc generating portion is reduced. However, by increasing the average welding voltage Vav, the arc length is lengthened and the size of the melted ground is increased, so that the heat input to the filler wire can be increased. Therefore, it is possible to compensate for a decrease in the amount of heat input to the filler wire due to the change in the distance Lt between the power supply tip and the base material. As a result, the molten state of the filler wire can be kept stable, and good welding quality can be obtained.

  As shown in FIG. 4D, the filler wire feed speed is reduced to Fw = Ft−ΔLw. Since the distance Lt between the power supply tip and the base material is shortened to Lt2, the distance Lw between the wires is increased to Lw2, and the heat input to the filler wire is reduced because the distance from the arc generating portion is reduced. However, since the feeding speed Fw of the filler wire is also decreased, the balance between the heat input amount to the filler wire and the feeding speed is maintained, so that the molten state of the filler wire can be stably maintained, which is favorable. Welding quality can be obtained.

  As shown in FIG. 5F, the inter-wire distance setting signal Lwr = Lwtr−ΔLw. Since the distance Lt between the power supply tip and the base material is shortened to Lt2, the distance Lw between the wires is increased to Lw2, and the heat input to the filler wire is reduced because the distance from the arc generating portion is reduced. However, since the inter-wire distance setting signal Lwr decreases, the inter-wire distance Lw approaches by a mechanism that adjusts the insertion position of the filler wire back and forth in the welding direction. As a result, a decrease in the heat input to the filler wire can be compensated, so that the molten state of the filler wire can be stably maintained, and good welding quality can be obtained.

(3) Period in which the distance Lt between the power supply tip and the base material at time t3 to t4 fluctuates in the direction of increasing to Lt3 During the period from time t3 to t4, as shown in FIG. This is a period during which the distance Lt between the base materials fluctuates and becomes longer to Lt3. In response to this, the average welding current Iav decreases to I3 as shown in FIG. The welding current change ΔI = I3−It, and the inter-wire distance change ΔLw = G · ΔI can be calculated. Here, since G is a positive constant, the change in distance between wires ΔLw <0.

  As shown in FIG. 5E, the welding voltage setting signal Vr is decreased to Vrt + ΔLw. In response to this, as shown in FIG. 5C, the average welding voltage Vav decreases to a value V3 corresponding to the welding voltage setting signal Vr. Since the distance Lt between the power supply tip and the base material is increased to Lt3, the distance Lw between the wires is decreased to Lw3, and the heat input to the filler wire is increased in order to approach the arc generating portion. However, by reducing the average welding voltage Vav, the arc length is shortened and the size of the molten ground is reduced, so that the amount of heat input to the filler wire can be reduced. Therefore, it is possible to compensate for an increase in the amount of heat input to the filler wire due to a change in the distance Lt between the power feed tip and the base material. As a result, the molten state of the filler wire can be kept stable, and good welding quality can be obtained.

  As shown in FIG. 4D, the filler wire feed speed is increased to Fw = Ft−ΔLw. Since the distance Lt between the power supply tip and the base material is increased to Lt3, the distance Lw between the wires is decreased to Lw3, and the heat input to the filler wire is increased in order to approach the arc generating portion. However, since the feeding speed Fw of the filler wire is also increased, the balance between the heat input amount to the filler wire and the feeding speed is maintained, so that the molten state of the filler wire can be stably maintained, which is favorable. Welding quality can be obtained.

  As shown in FIG. 5F, the inter-wire distance setting signal Lwr is increased to Lwtr−ΔLw. Since the distance Lt between the power supply tip and the base material is increased to Lt3, the distance Lw between the wires is decreased to Lw3, and the heat input to the filler wire is increased in order to approach the arc generating portion. However, since the inter-wire distance setting signal Lwr increases, the inter-wire distance Lw is increased by a mechanism that adjusts the insertion position of the filler wire in the front and rear directions in the welding direction. As a result, an increase in heat input to the filler wire can be compensated, so that the molten state of the filler wire can be stably maintained, and good welding quality can be obtained.

  In the above description, the welding voltage setting signal Vr (average welding voltage Vav), the filler wire feed speed Fw, and the inter-wire distance setting signal Lwr (inter-wire distance Lw) are all changed. It is sufficient to change at least one of them.

  FIG. 2 is a block diagram of a welding apparatus for carrying out the above-described two-wire welding control method according to Embodiment 1 of the present invention. This figure shows the case where the output control (arc length control) is the frequency modulation control described above. Hereinafter, each block will be described with reference to FIG.

  The power supply main circuit PM receives a commercial power supply (not shown) such as a three-phase 200 V as input, performs output control by inverter control according to a drive signal Dv described later, and generates a welding voltage Vw and a welding current Iw for generating the arc 3. Is output. Although not shown, this power main circuit PM is a primary rectifier circuit that rectifies commercial power, a capacitor that smoothes the rectified direct current, and an inverter circuit that converts the smoothed direct current into high frequency alternating current according to the drive signal Dv. A high-frequency transformer that steps down the high-frequency alternating current to an appropriate voltage value for generating the arc 3, a secondary rectifier circuit that rectifies the stepped-down high-frequency alternating current, and a reactor that smoothes the rectified direct current.

  The welding wire 1 is fed through the welding torch 4 by the rotation of the welding wire feeding roll 5 coupled to the welding wire feeding motor WM, and is fed from the power source main circuit PM through a feeding chip (not shown). Electric power is supplied, and an arc 3 is generated between the base material 2 and the base material 2. The filler wire 6 is fed through the filler wire guide 7 by the rotation of the filler wire feeding roll 8 coupled to the filler wire feeding motor FM, and is melted in a short-circuited state with the molten pool 2 formed by the arc 3. The

  The welding torch 4 and the filler wire guide 7 are integrated via a drive mechanism 9. Therefore, when the welding torch 4 changes in the vertical direction, the filler wire guide 7 also changes in the vertical direction. The drive mechanism 9 is a mechanism including a motor for moving the filler wire 6 in the front-rear direction of the welding direction with an inter-wire distance setting signal Lwr described later as an input. Conventionally, a mechanism for converting the rotational motion of the motor into a linear motion by a slider crank mechanism, a mechanism for converting the rotational motion of the motor into a swinging motion by a crank and a swing rod, and the like are used.

  The welding current detection circuit ID detects the welding current Iw and outputs a welding current detection signal Id. The average welding current calculation circuit IAV receives the welding current detection signal Id as an input, averages it (passes through a low-pass filter having a cutoff frequency of about 1 to 10 Hz), and outputs an average welding current signal Iav.

  The reference current value setting circuit ITR outputs a predetermined reference current value setting signal Itr. The reference current value setting signal Itr is an average welding current value when the diameter, material and feed speed of the welding wire 1 are determined and the distance Lt between the power supply tip and the base material is the set value Lt. The welding current change calculation circuit DI receives the average welding current signal Iav and the reference current value setting signal Itr, calculates ΔI = Iav−Itr, and outputs a welding current change signal ΔI. The inter-wire distance change calculation circuit DLW receives this welding current change signal ΔI, calculates ΔLw = G · ΔI, and outputs an inter-wire distance change signal ΔLw. G is a positive constant as described above.

  The reference voltage value setting circuit VTR outputs a predetermined reference voltage value setting signal Vtr. The welding voltage setting circuit VR receives the reference voltage value setting signal Vtr and the above-described inter-wire distance change signal ΔLw, calculates Vr = Vtr + ΔLw, and outputs the welding voltage setting signal Vr.

  The reference feed speed setting circuit FTR outputs a predetermined reference feed speed setting signal Ftr. The filler wire feed speed setting circuit FR receives the reference feed speed setting signal Ftr and the above-described inter-wire distance change signal ΔLw, calculates Fr = Ftr−ΔLw, and fills the filler wire feed speed setting signal Fr. Is output.

  The reference wire distance setting circuit LWTR outputs a predetermined reference wire distance setting signal Lwtr. The inter-wire distance setting circuit LWR receives the reference inter-wire distance setting signal Lwtr and the inter-wire distance change signal ΔLw, calculates Lwr = Lwtr−ΔLw, and outputs the inter-wire distance setting signal Lwr.

  The welding voltage detection circuit VD detects the welding voltage Vw and outputs a welding voltage detection signal Vd. The average welding voltage calculation circuit VAV receives the welding voltage detection signal Vd as an input, averages it (passes through a low-pass filter having a cutoff frequency of about 1 to 10 Hz), and outputs an average welding voltage signal Vav. The voltage error amplification circuit EV amplifies an error between the welding voltage setting signal Vr and the average welding voltage signal Vav, and outputs a voltage error amplification signal Ev.

  The voltage / frequency conversion circuit VF converts the signal into a signal having a frequency proportional to the value of the voltage error amplification signal Ev, and outputs a pulse period signal Tf having a high level for a short time at each frequency (pulse period). The frequency modulation control described above is performed by this voltage / frequency conversion circuit VF. The peak period setting circuit TPR outputs a predetermined peak period setting signal Tpr. The peak period timer circuit TP receives the pulse period signal Tf and the peak period setting signal Tpr as described above, and becomes the High level only for a period determined by the peak period setting signal Tpr from the time when the pulse period signal Tf changes to the High level. The peak period signal Tp is output. Therefore, the peak period signal Tp is a signal whose period is a pulse period, which is at a high level during the peak period and at a low level during the base period.

  The peak current setting circuit IPR outputs a predetermined peak current setting signal Ipr. The base current setting circuit IBR outputs a predetermined base current setting signal Ibr. The welding current setting circuit IR receives the peak period signal Tp, the peak current setting signal Ipr, and the base current setting signal Ibr, and sets the peak current when the peak period signal Tp is at a high level (peak period). The signal Ipr is output as the welding current setting signal Ir. When the level is the low level (base period), the base current setting signal Ibr is output as the welding current setting signal Ir. The current error amplification circuit EI amplifies an error between the welding current setting signal Ir and the welding current detection signal Id, and outputs a current error amplification signal Ei. The drive circuit DV receives the current error amplification signal Ei, performs PWM modulation control based on this signal, and based on the result, outputs a drive signal Dv for driving the inverter circuit in the power supply main circuit PM. Output.

  The welding wire feed speed setting circuit WR outputs a predetermined welding wire feed speed setting signal Wr. The welding wire feed control circuit WC supplies the welding wire feed control signal Wc for feeding the welding wire 1 at a feed speed corresponding to the value of the welding wire feed speed setting signal Wr. Output to motor WM.

  The filler wire feed control circuit FCT sends a filler wire feed control signal Fct for feeding the filler wire 6 at a feed rate corresponding to the value of the filler wire feed rate setting signal Fr. Output to feed motor FM.

  In this figure, the welding voltage setting signal Vr, the filler wire feed speed setting signal Fr, and the inter-wire distance setting signal Lwr are feedback-controlled by the inter-wire distance change signal ΔLw, but at least one of them is used. May be feedback-controlled.

  According to the first embodiment described above, a change in the distance between the power supply tip and the base material during welding is detected, and a parameter correlated with the heat input to the filler wire is fed back according to the change in the distance between the power supply tip and the base material. Control. The parameter is at least one of a welding voltage, a feeding speed of the filler wire, or a distance between the consumable electrode and the filler wire. As a result, even if the distance between the power supply tip and the base material fluctuates during welding, the distance between the wires fluctuates, and the heat input to the filler wire changes, the above parameters are feedback-controlled, thereby reducing the heat input. Can be compensated. For this reason, in this embodiment, in the two-wire welding method, even if the distance between the power supply tip and the base material varies during welding, the molten state of the filler wire can be kept stable and good welding quality can be obtained. .

[Embodiment 2]
In the invention of the second embodiment, the parameter is changed only when the fluctuation of the distance between the power feed tip and the base material becomes shorter than a predetermined reference value. The parameter is at least one of a welding voltage, a filler wire feeding speed, a distance between the consumable electrode and the filler wire, or a welding speed.

  FIG. 3 is a timing chart showing a two-wire welding control method according to Embodiment 2 of the present invention. FIG. 4A shows the time change of the distance Lt between the power feed tip and the base material, FIG. 2B shows the time change of the average welding current Iav, and FIG. 3C shows the time change of the average welding voltage Vav. (D) shows the time change of the feeding speed Fw of the filler wire, (E) shows the time change of the welding voltage setting signal Vr, and (F) shows the inter-wire distance setting signal Lwr. (G) shows the time change of the welding speed Sw. This figure corresponds to FIG. 1 described above, and the description of the same operation will not be repeated. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 6A, the power supply tip / base material distance Lt is a set value Lt1 during the period from time t1 to t2, and is Lt2 shorter than the set value during the period from time t2 to t3. Yes, during the period from time t3 to t4, Lt3 is longer than the set value. Here, Lt2 is a case where the set value Lt1 is shorter than the reference value. It is determined that Lt2 has become shorter than the reference value by the fact that the welding current change ΔI is a positive value and greater than the reference value.

(1) Period in which the distance Lt between the power feeding tip and the base material at time t1 to t2 is the set value Lt1 As shown in FIG. 5B, the welding current change ΔI = Iav−It≈0, which is less than the reference value Therefore, the operation during this period is the same as that in FIG. 1, and the description will not be repeated. However, as shown in FIG. 5G, the welding speed Sw is the reference welding speed St.

(2) Period in which the distance Lt between the power feed tip and the base material at time t2 to t3 fluctuates in the direction of shortening to Lt2, as shown in FIG. 5B, the welding current change ΔI = Iav−It = I2−It is Since the positive value is equal to or greater than the reference value, the distance Lt2 between the power feed tip and the base material is shorter than the set value Lt1 by the reference value or more. For this purpose, each parameter is feedback-controlled. Therefore, the operation during this period is the same as in FIG. That is, as shown in FIG. 5E, the welding voltage setting signal Vr increases to Vrt + ΔLw, and as shown in FIG. 5C, the average welding voltage Vav becomes a value V2 corresponding to the welding voltage setting signal Vr. To increase. As shown in FIG. 4D, the filler wire feed speed Fw = Ft−ΔLw. As shown in FIG. 5F, the distance between the wires is reduced to Lwr = Ltr−ΔLw.

  Further, as shown in FIG. 5G, the welding speed becomes Sw = St + ΔLw. Since the distance Lt between the power supply tip and the base material is shortened to Lt2, the distance Lw between the wires is increased to Lw2, and the heat input to the filler wire is reduced because the distance from the arc generating portion is reduced. However, since the welding speed Sw is increased, the melted ground has an elongated shape. As a result, the filler wire insertion position approaches the center of the melted area, and the decrease in the heat input to the filler wire can be compensated, so that the molten state of the filler wire can be stably maintained. Good welding quality can be obtained.

(3) Period in which the distance Lt between the power feed tip and the base material at times t3 to t4 fluctuates in the direction of increasing to Lt3 As shown in FIG. 5B, the welding current change ΔI = iAV−It = I3−It is Since it is a negative value, all parameters are not feedback controlled. Therefore, the operation of each parameter shown in FIGS. 5C to 5G during this period is the same as that during the period from time t1 to time t2 shown in FIG.

  Even during the period from time t2 to time t3, when the positive value of the welding current change ΔI is less than the reference value, all parameters are not feedback-controlled.

  In the above description, the case where feedback control is performed for all four parameters has been described. However, feedback control may be performed by selecting at least one of the parameters.

  The reason why the parameter is feedback-controlled only when the fluctuation of the distance between the power supply tip and the base material becomes shorter than the reference value is as follows. First, when the fluctuation of the distance between the power supply tip and the base material is long, the distance between the wires is shortened, so that the amount of heat input to the filler wire is increased. For this reason, the unsettled state of the filler wire that significantly deteriorates the welding quality does not occur. In this case, the bead appearance is a little worse and the influence on the welding quality is small. Similarly, when the fluctuation of the distance between the power supply tip and the base material is shortened by less than the reference value, the distance between the wires is slightly increased. For this reason, the amount of heat input to the filler wire is reduced. However, since the amount of phenomenon is small, the effect on welding quality is small. On the other hand, when the fluctuation of the distance between the power supply tip and the base material becomes shorter than the reference value, the distance between the wires becomes longer, and the heat input to the filler wire is considerably reduced. As a result, the unsettled state of the filler wire occurs. Therefore, in this case, the decrease in the heat input amount of the filler wire is compensated by feedback control of each parameter as described above. In this way, it is possible to shorten the time required for experiments such as parameter selection and optimization of feedback control gain, thereby improving production efficiency. The reference value for the fluctuation of the distance between the power supply tip and the base material is set to a value at which the welding quality cannot ensure the required quality.

  FIG. 4 is a block diagram of a welding apparatus for carrying out the above-described two-wire welding control method according to the second embodiment of the present invention. This figure corresponds to FIG. 2 described above, and the same reference numerals are given to the same blocks and their description will not be repeated. This figure is obtained by adding a reference welding speed setting circuit sTR and a welding speed setting circuit sR to FIG. Hereinafter, these blocks will be described with reference to FIG.

  The reference welding speed setting circuit sTR outputs a predetermined reference welding speed setting signal str. The welding speed setting circuit sR receives the reference welding speed setting signal str and the inter-wire distance change signal ΔLw, calculates sr = str + ΔLw, and uses the welding speed setting signal sr as a welding torch moving device outside the welding power source. (Not shown). The welding torch moving device is an automatic cart, a robot device, or the like. The welding torch moving device moves the welding torch 4 at a welding speed Sw determined by the welding speed setting signal Sr.

  According to the second embodiment described above, the parameter is changed only when the fluctuation of the distance between the power feed tip and the base material becomes shorter than a predetermined reference value. The parameter is at least one of a welding voltage, a filler wire feeding speed, a distance between the consumable electrode and the filler wire, or a welding speed. As a result, in addition to the effects of the first embodiment, parameter feedback control is performed only when it is the minimum necessary, so that the time required for experiments such as parameter selection and feedback control gain optimization can be reduced. , Production efficiency can be improved.

DESCRIPTION OF SYMBOLS 1 Welding wire 2 Base material 21 Weld pool 3 Arc 4 Welding torch 41 Feed tip 5 Welding wire feeding roll 6 Filler wire 7 Filler wire guide 8 Filler wire feeding roll 9 Drive mechanism DI Welding current change calculation circuit DLW Distance between wires Change calculation circuit DV Drive circuit Dv Drive signal EI Current error amplification circuit Ei Current error amplification signal EV Voltage error amplification circuit Ev Voltage error amplification signal FCT Filler wire feed control circuit Fct Filler wire feed control signal FM Filler wire feed motor FR Filler wire feeding speed setting circuit Fr Filler wire feeding speed setting signal Ft Reference feeding speed FTR Reference feeding speed setting circuit Ftr Reference feeding speed setting signal Fw Feeding speed IAV Average welding current calculation circuit Iav Average welding current ( signal)
Ib Base current IBR Base current setting circuit Ibr Base current setting signal ID Welding current detection circuit Id Welding current detection signal Ip Peak current IPR Peak current setting circuit Ipr Peak current setting signal IR Welding current setting circuit Ir Welding current setting signal It Reference current value ITR Reference current value setting circuit Itr Reference current value setting signal Iw Welding current Lt Power supply tip / base material distance Lw Wire distance LWR Wire distance setting circuit Lwr Wire distance setting signal LWTR Reference wire distance setting circuit Lwtr Between reference wires Distance setting signal P1, p2 Position PM Power supply main circuit sR Welding speed setting circuit Sr Welding speed setting signal St Reference welding speed sTR Reference welding speed setting circuit str Reference welding speed setting signal Sw Welding speed Tb Base period Tf Pulse period (signal)
TP Peak period timer circuit Tp Peak period (signal)
TPR Peak period setting circuit Tpr Peak period setting signal VAV Average welding voltage calculation circuit Vav Average welding voltage (signal)
Vb base voltage VD welding voltage detection circuit Vd welding voltage detection signal VF voltage / frequency conversion circuit Vp peak voltage VR welding voltage setting circuit Vr welding voltage setting signal Vt reference voltage value VTR reference voltage value setting circuit Vtr reference voltage value setting signal Vw welding Voltage WC Welding wire feed control circuit Wc Welding wire feed control signal WM Welding wire feed motor WR Welding wire feed speed setting circuit Wr Welding wire feed speed setting signal ΔI Welding current change (signal)
ΔLw Distance change between wires (signal)

Claims (4)

A welding voltage is applied between the consumable electrode fed from the power supply tip and the base material to generate an arc to form a molten pool, and a filler wire having a forward angle is fed to the rear of the molten pool In the 2-wire welding control method of welding while
Detecting a change in the distance between the power supply tip and the base material during welding, and feedback-controlling a parameter correlated with the heat input to the filler wire according to the change in the distance between the power supply tip and the base material,
A two-wire welding control method characterized by the above. The parameter is at least one of the welding voltage, a feeding speed of the filler wire, or a distance between wires of the consumable electrode and the filler wire.
The two-wire welding control method according to claim 1. Only when the fluctuation of the distance between the power supply chip and the base material is shorter than a predetermined reference value, the parameter is changed.
The two-wire welding control method according to claim 1. The parameter is at least one of the welding voltage, a feeding speed of the filler wire, a distance between the consumable electrode and the filler wire, or a welding speed.
The two-wire welding control method according to claim 3.

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