JP6525625B2 - 2-wire welding control method - Google Patents

Description

  According to the present invention, a welding voltage is applied between the consumable electrode supplied from the feed tip and the base material to generate an arc to form a molten pool, and a filler wire having a forward angle is placed at the rear of the molten pool The present invention relates to a two-wire welding control method of welding while being fed.

  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 molten metal is increased, and high-speed and highly efficient welding is possible. In particular, when performing high-speed welding by a two-wire welding method, it is important to short-circuit and feed the filler wire to the molten pool from behind the consumable electrode arc in order to prevent it from becoming a humping bead. This suppresses the humping bead because when the filler wire is fed into the consumable electrode arc and melted, the molten pool is hardly cooled and the filler wire can not suppress the swelling of the latter half of the molten pool. It is because there is no effect. On the other hand, if the filler wire is short-circuited and fed to the rear part of the molten pool at the edge of the arc and melted by the heat of the molten pool, the molten pool is cooled and the filler wire later cools the molten pool Can be suppressed to suppress the formation of humping beads. Therefore, in the two-wire welding method of the prior art, the molten pool is cooled by shorting the filler wire with the molten pool in a cold state without applying a current to the filler wire.

  In the two-wire welding method, various consumable electrodes such as carbon dioxide gas arc welding, mag welding, mig welding, pulse arc welding, AC arc welding, etc. are generated as a method of generating an arc between a welding wire and a base material. Arc welding can be used. In addition, the filler wire basically has a short-circuited between the wire tip and the molten pool, and is melted by the heat from the molten pool. Therefore, no arc is generated between the filler wire and the molten pool. In the present invention, although the case where pulse arc welding is used as the consumable electrode type arc welding is described, other welding may be used. Further, in the following description, the base material and the molten pool are used in the same meaning.

  FIG. 5 is a current-voltage waveform diagram in a two-wire welding method using pulse arc welding. The figure (A) shows the time change of welding current Iw which energizes a welding wire, and the figure (B) shows the time change of welding voltage Vw applied between a welding wire and a base material (fusion pool), The same figure (C) shows the time change of feed speed Fw of a filler wire. Although the feed speed of the welding wire is not shown, it is fed at a predetermined value. No voltage is applied between the filler wire and the molten pool, and no current flows. The filler wire is fed shorted to the molten pool, as described above. Even if the filler wire separates from the molten pool, no arc is generated between the filler wire and the molten pool because no voltage is applied. This will be described below with reference to the same figure.

  During the peak period Tp from time t1 to t2, as shown in FIG. 6A, the peak current Ip having a large current value equal to or larger than the critical value is supplied to transfer the droplet from the welding wire. As shown in), a peak voltage Vp proportional to the arc length is applied between the welding wire and the weld pool.

  During the base period Tb from time t2 to t3, as shown in FIG. 6A, the base current Ib of a small current value smaller than the critical value is supplied to prevent formation of droplets, and FIG. As shown in), a base voltage Vb is applied. Welding is performed with the period from time t1 to t3 being repeated as one period (pulse period Tf).

  As shown in FIG. 6C, the feed speed Fw of the filler wire is a constant value, and is set to a feed speed that causes stable melting due to heat input from the melt in a state of being short-circuited with the melt. The feed speed Fw of the filler wire is often set in the range of about 20 to 30% of the feed speed of the welding wire.

  Incidentally, 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 of the welding power source (arc length control) is performed. The arc length is substantially in proportion 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. 7A so that the detected value becomes equal to the welding voltage setting value corresponding to the appropriate arc length. Do. Since the average welding voltage Vav is larger than the welding voltage set value when the arc length is longer than the appropriate value, the average welding current Iav is reduced to reduce the wire melting speed so that the arc length is shortened. 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 the average welding current Iav is increased to increase the wire melting speed so that the arc length becomes longer. Do. As the above-mentioned average welding voltage Vav, generally, a value obtained by passing the welding voltage Vw through a low pass filter (cutoff frequency of about 1 to 10 Hz) is 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 performing feedback control with the pulse period Tf as the manipulated variable, 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). In addition, 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, it is set to about Ip = 450 A, Ib = 50 A and Tp = 1.2 ms. 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 the characteristics such as the feed speed, feed resistance, and vibration generated by the feed of the filler wire is detected and applied to the feed speed of the filler wire or the filler wire. Control the preheating current. For this reason, it is possible to prevent a weld defect of filler wire melting residue caused by fluctuation of welding conditions due to disturbance or setting error of welding conditions while limiting heat input to the base material or keeping welding amount and leg length. It is stated that it can.

  FIG. 6 is a front view of a welding torch for explaining that in the two-wire welding method, the distance Lw between the welding wire 1 and the filler wire 6 changes when the distance Lt between the feeding tip and the base material changes. FIG. The figure (A) is a case where distance Lt = Lt1 of a feed tip and a base material is a setting value, and the figure (B) is a case where distance Lt = Lt2 between a feed tip and a base material becomes shorter than a set value. FIG. 7C shows the case where the distance Lt = Lt3 between the feeding tip and the base material is longer than the set value. This will be described below with reference to the same figure.

  As shown in the figure (A), the welding proceeds in the left direction. The welding wire 1 is fed straight to the base material 2 from the feed tip 41 in the welding torch 4, and an arc 3 is generated. A molten zone 21 is formed by the arc 3. The filler wire 6 is fed in a short circuit state on the molten land 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 feeding tip and the base material is the set value of Lt1 [mm]. Lt1 is set to about 15 mm. The distance Lw between the position P1 at which the feed direction of the welding wire 1 and the surface of the base material 2 cross and the position P2 at which the filler wire 6 shorts to the base material 2 (molten land 21) is the inter-wire distance Lw. In the figure (A), it is Lw1 [mm]. Lw1 is about 3 mm.

  The figure (B) is a case where distance Lt between electric power feeding tip and base material becomes short to Lt 2 during welding. Therefore, Lt2 <Lt1. Since the filler wire guide 7 is integral with the welding torch 4, the filler wire 6 also approaches the base material 2 when the distance Lt between the feed tip and the base material becomes short. As a result, the inter-wire distance Lw becomes Lw2, which is longer than Lw1. That is, when the distance Lt between the feeding tip and the base material fluctuates in the direction of shortening, the distance Lw between the wires changes in the direction of lengthening.

  FIG. 7C shows the case where the distance Lt between the feeding tip and the base material is increased to Lt3. In this case, the inter-wire distance Lw becomes short to Lw3.

  The distance Lt between the feed tip and the base material fluctuates during welding due to the variation in the processing accuracy of the workpiece, the variation in the fixed position of the workpiece, the thermal deformation of the workpiece during welding, and the like. The variation in the distance Lt between the feeding tip and the base material changes the distance Lw between the wires. 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 when the distance Lt between the feed tip and the base material changes by several mm. When the inter-wire distance Lw changes, the amount of heat input from the melting place 21 to the filler wire 6 changes, so the molten state changes. For this reason, a stable molten state collapses and welding quality, such as bead appearance, will deteriorate.

JP, 2010-167489, A Unexamined-Japanese-Patent No. 2002-28784

In order to solve the problems described above, the invention of claim 1 is
A welding voltage is applied between the consumable electrode supplied from the feed 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 two-wire welding control method for welding while
Detects fluctuations in the distance between the feed tip and the base metal during welding,
Only when the distance between the feeding tip and the base material becomes shorter than a predetermined set value by a predetermined reference value or more , the amount of heat input to the filler wire is correlated with the variation of the distance between the feeding tip and the base material. Control the parameters to be
It is a 2 wire welding control method characterized by things.

The invention according to claim 2, claim wherein said parameter is the welding voltage, feed rate of the filler wire, wherein at least one of inter-wire distance or welding speed of the consumable electrode and the filler wire, it is characterized by 1 is a 2 wire welding control method according.

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

  According to the present invention, the distance between the feed tip and the base material fluctuates during welding to change the distance between the wires, and even if the amount of heat input to the filler wire changes, the parameter correlating with the amount of heat input is feedback controlled. Thus, the heat input can be compensated. For this reason, according to the present invention, in the two-wire welding method, even if the distance between the feed tip and the base material changes during welding, the molten state of the filler wire can be stably maintained, and good welding quality can be obtained.

It is a timing chart which shows a 2 wire welding control method concerning Embodiment 1 of the present invention. It is a block diagram of a welding device for enforcing a 2 wire welding control method concerning Embodiment 1 of the present invention. It is a timing chart which shows the 2 wire welding control method concerning Embodiment 2 of the present invention. It is a block diagram of a welding device for enforcing a 2 wire welding control method concerning Embodiment 2 of the present invention. In the prior art, it is an electric current and voltage waveform figure in the 2 wire welding method which used pulse arc welding. FIG. 17 is a schematic view of a welding torch tip for illustrating that the inter-wire distance Lw between the welding wire 1 and the filler wire 6 changes when the distance Lt between the feeding tip and the base material changes in the two-wire welding method. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment
The invention of the first embodiment detects a variation in the distance between the feeding tip and the base material during welding, and feedback controls a parameter correlating with the amount of heat input to the filler wire according to the variation in the distance between the feeding tip and the base material. It is a thing. 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. The figure (A) shows the time change of the distance Lt between the feeding tip and the base material, the figure (B) shows the time change of the average welding current Iav, and the figure (C) shows the time change of the average welding voltage Vav. The figure (D) shows the time change of feed speed Fw of filler wire, the figure (E) shows the time change of welding voltage setting signal Vr, and the figure (F) shows the distance setting signal Lwr between wires. Change over time. As described above with reference to FIG. 5, the average welding current Iav is obtained by averaging (smoothing) the welding current Iw of the pulse waveform, and the average welding voltage Vav is obtained by averaging (smoothing) the welding voltage Vw of the pulse waveform. is there. The feeding speed of the welding wire is not shown but is fed at a predetermined constant value. No voltage is applied between the filler wire and the molten pool, and no current flows. The filler wire is fed shorted to the rear of the melt with an advancing angle as described above. Even if the filler wire separates from the molten pool, no arc is generated between the filler wire and the molten pool because no voltage is applied. This will be described below with reference to the same figure.

(1) A period in which the distance Lt between the feeding 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, as shown to the figure (B), the average welding current Iav has become the reference current value It. The welding voltage setting signal Vr is a reference voltage setting value Vtr as shown in FIG. 6E, and the average welding voltage Vav is a reference corresponding to the reference voltage setting value Vtr as shown in FIG. The voltage value is Vt. As shown to the figure (D), the feed speed Fw of a filler wire has become the reference | standard feed speed Ft. As shown in FIG. 6F, the inter-wire distance setting signal Lwr is a set value Lwtr. That is, by the welding operator, the feed tip-base material distance Lt is set to the set value Lt1, the wire distance Lw is set to the set value Lw1, and the welding voltage set signal Vr is set to the reference voltage set value Vtr. Fw is set to the reference feed speed Ft.

(2) A period in which the distance Lt between the feeding tip and the base material in the time t2 to t3 changes in the direction of shortening to Lt2 During the period from the time t2 to t3, as shown in FIG. The period during which the distance Lt between the base members fluctuates and shortens to Lt2. In response to this, as shown in the figure (B), the average welding current Iav increases to I2. The welding current variation ΔI = I2−It is obtained, and it can be calculated as the wire distance variation ΔLw = G · ΔI. Here, G is a positive constant.

  As shown in FIG. 6E, the welding voltage setting signal Vr is increased to Vrt + ΔLw. In response to this, as shown in FIG. 6C, the average welding voltage Vav increases to a value V2 corresponding to the welding voltage setting signal Vr. Since the distance Lt between the feeding 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 decreased because the distance Lw is farther from the arc generating portion. However, by increasing the average welding voltage Vav, the arc length is increased and the size of the molten metal is increased, so that the heat input to the filler wire can be increased. Therefore, it is possible to compensate for the decrease in heat input to the filler wire due to the fluctuation of the distance Lt between the feeding 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 to the same figure (D), it reduces to feed speed Fw = Ft-deltaLw of filler wire. Since the distance Lt between the feeding 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 decreased because the distance Lw is farther from the arc generating portion. However, since the feed speed Fw of the filler wire is also reduced, a balance between heat input to the filler wire and the feed speed is maintained, so that the molten state of the filler wire can be stably maintained, which is favorable. Weld quality can be obtained.

  As shown in FIG. 6F, the inter-wire distance setting signal Lwr is reduced to Lwtr−ΔLw. Since the distance Lt between the feeding 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 decreased because the distance Lw is farther from the arc generating portion. 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, since the decrease in heat input to the filler wire can be compensated, the molten state of the filler wire can be stably maintained, and good welding quality can be obtained.

(3) A period in which the distance Lt between the feeding tip and the base material at time t3 to t4 fluctuates in the direction of becoming longer to Lt3 During the period from time t3 to t4, as shown in FIG. The period in which the distance Lt between base metals 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 variation ΔI = I3-It is obtained, and it can be calculated as the wire-to-wire distance variation ΔLw = G · ΔI. Here, since G is a positive constant, the change in distance between wires ΔLw <0.

  As shown in FIG. 6E, the welding voltage setting signal Vr is reduced to Vrt + ΔLw. In response to this, as shown in FIG. 6C, the average welding voltage Vav decreases to a value V3 corresponding to the welding voltage setting signal Vr. Since the distance Lt between the feeding tip and the base material is long to Lt3, the distance Lw between the wires becomes short to Lw3, and the amount of heat input to the filler wire becomes large because the distance Lw approaches the arc generation portion. However, by reducing the average welding voltage Vav, the arc length is shortened and the size of the molten metal is reduced, so the amount of heat input to the filler wire can be reduced. Therefore, it is possible to compensate for the increase in heat input to the filler wire due to the fluctuation of the distance Lt between the feeding 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 to the same figure (D), it is made to increase to feed speed Fw = Ft-deltaLw of filler wire. Since the distance Lt between the feeding tip and the base material is long to Lt3, the distance Lw between the wires becomes short to Lw3, and the amount of heat input to the filler wire becomes large because the distance Lw approaches the arc generation portion. However, since the filler wire feeding speed Fw is also increased, the molten state of the filler wire can be stably maintained because the heat input to the filler wire is balanced with the feeding speed, which is favorable. Weld quality can be obtained.

  As shown in FIG. 6F, the inter-wire distance setting signal Lwr is increased to Lwtr−ΔLw. Since the distance Lt between the feeding tip and the base material is long to Lt3, the distance Lw between the wires becomes short to Lw3, and the amount of heat input to the filler wire becomes large because the distance Lw approaches the arc generation portion. However, since the inter-wire distance setting signal Lwr increases, the inter-wire distance Lw is separated by the mechanism for adjusting the insertion position of the filler wire back and forth in the welding direction. As a result, since the increase in heat input to the filler wire can be compensated, 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), filler wire feeding speed Fw and 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 two-wire welding control method according to the first embodiment of the present invention described above. This figure shows the case where the output control (arc length control) is the frequency modulation control described above. Each block will be described below with reference to the figure.

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

  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 from the above-mentioned main power circuit PM via a feeding tip (not shown). Power is supplied to generate an arc 3 with the base material 2. The filler wire 6 is fed in the filler wire guide 7 by the rotation of the filler wire feed roll 8 coupled to the filler wire feed motor FM, and is melted in a short circuit with the molten pool 2 formed by the arc 3 Ru.

  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 longitudinal direction of the welding direction with the inter-wire distance setting signal Lwr described later as an input. As this mechanism, a mechanism for converting the rotational movement of the motor into a linear movement by a slide crank mechanism, and a mechanism for converting the rotational movement of the motor into a rocking movement by a crank and a rocking rod are conventionally used.

  The welding current detection circuit ID detects the above-mentioned welding current Iw and outputs a welding current detection signal Id. Average welding current calculation circuit IAV takes this welding current detection signal Id as an input, performs averaging (passing through a low pass filter with 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, the material, and the feeding speed of the welding wire 1 are determined, and the distance Lt between the feeding tip and the base material is the setting value Lt. The welding current change calculation circuit DI receives the above average welding current signal Iav and the above reference current value setting signal Itr, calculates .DELTA.I = Iav-Itr, and outputs a welding current change signal .DELTA.I. Inter-wire distance change calculation circuit DLW receives this welding current change signal ΔI as input, calculates ΔLw = G · ΔI, and outputs inter-wire distance change signal ΔLw. G is a positive constant as described above.

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

  The reference feed speed setting circuit FTR outputs a predetermined reference feed speed setting signal Ftr. Filler wire feeding speed setting circuit FR receives this reference feeding speed setting signal Ftr and the above-mentioned inter-wire distance variation signal ΔLw as input to calculate Fr = Ftr−ΔLw, and filler wire feeding speed setting signal Fr Output

  The reference inter-wire distance setting circuit LWTR outputs a predetermined reference inter-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 as input, calculates Lwr = Lwtr−ΔLw, and outputs an 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. Average welding voltage calculation circuit VAV takes this welding voltage detection signal Vd as an input, performs averaging (passing through a low pass filter with 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 to output 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 described above, and outputs a pulse periodic signal Tf that becomes High level for a short time for each frequency (pulse period). The above-described frequency modulation control is performed by the 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 above pulse period signal Tf and the above peak period setting signal Tpr, and becomes high level only during a period determined by the peak period setting signal Tpr from the time when the pulse period signal Tf changes to 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 high during the peak period, and low 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 above peak period signal Tp, the above peak current setting signal Ipr and the above base current setting signal Ibr as input, and sets the peak current when the peak period signal Tp is High level (peak period) The signal Ipr is output as the welding current setting signal Ir, and at 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. Drive circuit DV receives this current error amplification signal Ei as input, performs PWM modulation control based on this signal, and based on the result, drive signal Dv for driving the inverter circuit in the above-mentioned main power supply circuit PM. Output.

  The welding wire feeding speed setting circuit WR outputs a predetermined welding wire feeding speed setting signal Wr. The welding wire feed control circuit WC feeds 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 feeds the filler wire feed control signal Fct for feeding the filler wire 6 at a feed speed corresponding to the value of the filler wire feed speed setting signal Fr described above. Output to feed motor FM.

  In the figure, the welding voltage setting signal Vr, the filler wire feeding 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.

Second Embodiment
The invention of the second embodiment changes the parameter only when the distance between the feeding tip and the base material is shorter than a predetermined setting value by a predetermined reference value or more. The parameter is at least one of a welding voltage, a feeding speed of the filler wire, a distance between the consumable electrode and the filler wire, or a welding speed.

Second Embodiment
The invention of the second embodiment changes the parameter only when the variation of the distance between the feeding tip and the base material becomes shorter than a predetermined reference value. The parameter is at least one of a welding voltage, a feeding speed of the filler wire, 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 a second embodiment of the present invention. The figure (A) shows the time change of the distance Lt between the feeding tip and the base material, the figure (B) shows the time change of the average welding current Iav, and the figure (C) shows the time change of the average welding voltage Vav. The figure (D) shows the time change of feed speed Fw of filler wire, the figure (E) shows the time change of welding voltage setting signal Vr, and the figure (F) shows the distance setting signal Lwr between wires. (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. This will be described below with reference to the same figure.

  As shown in FIG. 6A, the distance Lt between the feed tip and the base material is the set value Lt1 during the period from time t1 to t2, and Lt2 shorter than the set value during the period from time t2 to t3. In the period from time t3 to time t4, Lt3 is longer than the set value. Here, Lt2 is a case where the reference value is shorter than the set value Lt1. It is determined that the welding current variation ΔI is a positive value and is not less than the reference value that Lt2 has become shorter than the reference value.

(1) A period during which the distance Lt between the feeding tip and the base material at time t1 to t2 is the set value Lt1 As shown in FIG. 6B, the welding current variation ΔI = Iav−It ≒ 0, which is less than the reference value Because the operation during this period is the same as that of FIG. 1, the description will not be repeated. However, as shown to the figure (G), the welding speed Sw is the reference welding speed St.

(2) A period during which the distance Lt between the feeding tip and the base metal fluctuates in the direction of shortening to Lt2 from time t2 to t3 As shown in FIG. 6B, the welding current variation ΔI = Iav−It = I2-It The distance Lt2 between the feed tip and the base material is shorter than the set value Lt1 by the reference value or more because it is a positive value and is equal to or larger than the reference value. 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 is increased to Vrt + ΔLw, and as shown in FIG. 4C, the average welding voltage Vav has a value V2 corresponding to the welding voltage setting signal Vr. To increase. As shown to the same figure (D), it reduces to feed speed Fw = Ft-deltaLw of a filler wire. As shown in FIG. 6F, the inter-wire distance setting signal Lwr = Ltr−ΔLw is reduced.

  Furthermore, as shown to the figure (G), it becomes early to welding speed Sw = St + deltaLw. Since the distance Lt between the feeding 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 decreased because the distance Lw is farther from the arc generating portion. However, since the welding speed Sw is increased, the molten land has an elongated shape. As a result, the insertion position of the filler wire comes close to the center of the molten area, and the decrease in 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) A period during which the distance Lt between the feeding tip and the base metal in the time t3 to t4 fluctuates in the direction of becoming longer to Lt3 As shown in the figure (B), the welding current variation ΔI = iAV−It = I3-It As it is a negative value, all parameters are not feedback controlled. Therefore, the operation of each parameter in the same figure (C)-(G) in this period becomes the same operation as the period of time t1-t2 of the same figure unlike FIG.

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

The reason for feedback control of the parameter only when the distance between the feeding conductive tip-base is shortened than the reference value than the set value is as follows. First, when the distance between the feeding tip and the base material is in the direction longer than the set value , the distance between the wires becomes short, and the amount of heat input to the filler wire is increased. For this reason, the unmelted state of the filler wire that would significantly deteriorate the welding quality does not occur. In this case, the bead appearance is a little worse and the influence on the weld quality is small. Similarly, when the distance between the feeding tip and the base material becomes shorter than the set value by less than the reference value, the distance between the wires becomes slightly longer. Because of this, the heat input to the filler wire is reduced. However, since the amount of phenomena is small, the influence on welding quality is small. On the other hand, when the distance between the feeding tip and the base material becomes shorter than the set value by the reference value or more, the distance between the wires becomes longer, and the heat input to the filler wire is considerably reduced. As a result, an unfilled state of the filler wire will occur. Therefore, in this case, the decrease in heat input of the filler wire is compensated for by feedback control of each parameter as described above. In this way, it is possible to shorten the time required for experiments such as selection of parameters and optimization of the gain of feedback control, thereby improving production efficiency. The above reference value is set to a value at which the welding quality can not ensure the required quality.

  The reason for feedback control of the parameters only when the variation of the distance between the feeding tip and the base material becomes shorter than the reference value is as follows. First, when the fluctuation of the distance between the feeding tip and the base material is in the long direction, the distance between the wires becomes short, so that the amount of heat input to the filler wire is increased. For this reason, the unmelted state of the filler wire that would significantly deteriorate the welding quality does not occur. In this case, the bead appearance is a little worse and the influence on the weld quality is small. Similarly, when the variation of the distance between the feeding tip and the base material becomes shorter than the reference value, the distance between the wires becomes slightly longer. Because of this, the heat input to the filler wire is reduced. However, since the amount of phenomena is small, the influence on welding quality is small. On the other hand, when the variation of the distance between the feeding tip and the base material becomes shorter than the reference value, the distance between the wires becomes long, and the heat input to the filler wire is considerably reduced. As a result, an unfilled state of the filler wire will occur. Therefore, in this case, the decrease in heat input of the filler wire is compensated for by feedback control of each parameter as described above. In this way, it is possible to shorten the time required for experiments such as selection of parameters and optimization of the gain of feedback control, thereby improving production efficiency. The reference value of the variation of the distance between the feeding tip and the base material is set to a value at which the welding quality can not ensure the required quality.

  FIG. 4 is a block diagram of a welding apparatus for implementing the two-wire welding control method according to the second embodiment of the present invention described above. 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 the reference welding speed setting circuit sTR and the welding speed setting circuit sR to FIG. Hereinafter, these blocks will be described with reference to the figure.

  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 as input, calculates sr = str + ΔLw, and generates a welding speed setting signal sr as a welding torch moving device outside the welding power source Output to (not shown). The welding torch moving device is an automatic carriage, 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 variation of the distance between the feeding tip and the base material becomes shorter than a predetermined reference value. The parameter is at least one of a welding voltage, a feeding speed of the filler wire, 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, feedback control of parameters is performed only in the minimum necessary case, so that the time required for experiments such as selection of parameters and optimization of gain for feedback control can be shortened. , Can improve the production efficiency.

DESCRIPTION OF SYMBOLS 1 welding wire 2 base material 21 molten pool 3 arc 4 welding torch 41 electric power feeding tip 5 welding wire feed roll 6 filler wire 7 filler wire guide 8 filler wire feed roll 9 drive mechanism DI welding current change calculation circuit DLW distance between wires Variation 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 Distance between feeding tip and base material Lw Distance between wires LWR Distance between wires setting circuit Lwr Distance between wires setting signal LWTR Reference distance between wires setting circuit Lwtr Reference wire between wires Distance setting signal P1, p2 Position PM Power 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 feeding control circuit Wc Welding wire feeding control signal WM Welding wire feeding motor WR Welding wire feeding speed setting circuit Wr Welding wire feeding speed setting signal ΔI Welding current change (signal)
ΔLw Change in distance between wires (signal)

Claims (2)

A welding voltage is applied between the consumable electrode supplied from the feed 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 two-wire welding control method for welding while
Detects fluctuations in the distance between the feed tip and the base metal during welding,
Only when the distance between the feeding tip and the base material becomes shorter than a predetermined set value by a predetermined reference value or more , the amount of heat input to the filler wire is correlated with the variation of the distance between the feeding tip and the base material. Control the parameters to be
A two-wire welding control method characterized in that. The parameter is at least one of the welding voltage, the feeding speed of the filler wire, the distance between the consumable electrode and the filler wire, or the welding speed.
The two-wire welding control method according to claim 1 , characterized in that:

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