JP2013059767A - Method for controlling crater in two-wire welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a sound crater portion in two-wire welding.SOLUTION: The method for controlling crater in two-wire welding comprises generating arc during a steady state period (before a time t1) by applying a welding voltage Vww between a welding wire and a base material and energizing a welding current Iww, and feeding (Fs) a filler wire into a molten pool formed by the arc while contacting. During a crater period Tc, a crater treatment is performed by energizing the current Iwf to the filler wire while maintaining the arc generating between the welding wire and the base material. For more detail, the crater treatment is performed by generating the arc for a crater period between the welding wire and the base material, and feeding while contacting the filler wire preheated by energization of the current Iwf into the molten pool. Thus, since the molten pool is efficiently cooled and the filler wire is completely melted, a sound weld bead can be formed.

Description

  The present invention relates to a crater control method for two-wire welding for suppressing cracks generated in a crater part in two-wire welding performed by feeding a filler wire in contact with a molten pool of a consumable electrode arc.

  The two-wire welding method in which the filler wire is fed while being brought into contact with the molten pool formed by the consumable electrode arc is a high-speed weldability because two wires of the consumable electrode arc and the filler wire are used. And excellent weldability. In particular, when high-speed welding is performed by the two-wire welding method, it is important to feed the filler wire in contact with the molten pool from behind the consumable electrode arc in order to prevent a humping bead. This is because when the filler wire is fed into the consumable electrode arc and melted, the cooling effect of the molten pool is reduced, and the rise of the latter half of the molten pool cannot be suppressed by the filler wire. This is because there is almost no suppression effect. On the other hand, if the filler wire is fed in contact with the second half of the molten pool at the peripheral edge of the arc and melted by the heat of the molten pool, the molten pool is efficiently cooled and melted by the filler wire. The latter half of the pond is suppressed and the formation of the humping bead can be suppressed. In the following description, the wire of the consumable electrode arc is described as a welding wire and is distinguished from the filler wire. As a welding method for generating a consumable electrode arc, a carbon dioxide arc welding method, a mag welding method, a MIG welding method, a pulse mag welding method, a pulse MIG welding method, a consumable electrode AC pulse arc welding method, or the like is used.

  At the end of the two-wire welding, the crater process by the consumable electrode arc is performed with the welding torch stopped, and the filler wire feeding is stopped. The reason for stopping the feeding of the filler wire during the crater period is as follows. During the crater period, in order to form a sound crater portion, the feeding speed of the welding wire is slowed to about 40 to 70% of the steady period. As a result, the value of the welding current for energizing the consumable electrode arc also decreases, so that the temperature of the molten pool also decreases from the steady period. For this reason, if the filler wire is fed to the molten pool during the crater period, the filler wire cannot be melted sufficiently, resulting in poor melting. Therefore, in the two-wire welding, it is common to stop the filler wire feeding during the crater period and perform the crater treatment only by the consumable electrode arc (see, for example, Patent Document 1). Here, the crater treatment is to form a healthy bead portion by filling a weld pool in a state where the welding torch reaches and stops at the welding end position and is depressed by an arc with a welding wire.

JP 2009-154173 A

  As described above, in the conventional two-wire welding, the feeding of the filler wire is stopped during the crater period, and the crater process is performed only by the consumable electrode arc. However, in joints such as narrow groove joints, when the filler wire is stopped and the crater treatment is performed only by the consumable electrode arc, cracks may occur in the crater portion, resulting in welding defects. This is because the feeding of the filler wire is stopped, so that the molten pool during the crater period cannot be efficiently cooled as in the steady period.

  Therefore, an object of the present invention is to provide a two-wire welding crater control method capable of suppressing the occurrence of cracks in the crater part in crater processing for a narrow groove joint or the like by two-wire welding.

In order to solve the above-described problems, the invention of claim 1 is characterized in that an arc is generated between a welding wire and a base material during a steady period, and a filler wire is brought into contact with a molten pool formed by the arc. In the 2-wire welding crater control method performed while feeding
During the crater period, a crater process is performed by passing a current through the filler wire in a state where the arc is generated.
This is a two-wire welding crater control method.

The invention of claim 2 makes the feeding speed of the welding wire during the crater period slower than the feeding speed during the steady period, and sets the feeding speed of the filler wire during the crater period during the steady period. The feeding speed of the filler wire during the crater period is slower than the feeding speed of the welding wire during the crater period,
The two-wire welding crater control method according to claim 1.

  According to the present invention, during the crater period, a crater process is performed by supplying a current to the filler wire in a state where an arc between the welding wire and the base material is generated. As a result, in crater processing for narrow gap joints by 2-wire welding, the molten pool during the crater period is efficiently cooled by inserting the filler wire preheated by energization of the current, and the filler wire is completely Since it can fuse | melt, it can suppress that a crack generate | occur | produces in a crater part.

It is a block diagram of the welding apparatus for enforcing the crater control method of 2 wire welding which concerns on embodiment of this invention. FIG. 2 is a block diagram of a welding wire welding power source PSW that constitutes the welding apparatus described above in FIG. 1. FIG. 2 is a block diagram of a filler wire welding power source PSF constituting the welding apparatus described above in FIG. 1. It is a timing chart of each signal in Drawing 1 for explaining a crater control method of 2 wire welding concerning an embodiment of the invention.

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

  FIG. 1 is a configuration diagram of a welding apparatus for carrying out a two-wire welding crater control method according to an embodiment of the present invention. Hereinafter, each component will be described with reference to FIG.

  This welding apparatus includes a welding torch WT surrounded by a broken line, a welding wire welding power source PSW, a filler wire welding power source PSF, a robot control device RC, and a robot (not shown). The welding torch WT includes carbon dioxide gas and carbon dioxide gas from the tip of the welding torch WT provided with a welding wire power supply tip 4a for supplying power to the welding wire 1a and a filler wire power supply tip 4b for supplying power to the filler wire 1b. A shielding gas (not shown) such as a mixed gas of oxygen and argon gas is ejected. The welding torch WT is held by a robot (not shown) and moved along the weld line according to a work program stored in the robot controller RC.

  The welding wire 1a is fed to the inside of the welding torch WT at the welding wire feeding speed Ws by the rotation of the welding wire feeding roll 5a coupled to the welding wire feeding motor WM. A consumable electrode arc 3a is generated. The filler wire 1b is fed through the welding torch WT at the filler wire feed speed Fs by the rotation of the filler wire feed roll 5b coupled to the filler wire feed motor FM, and is fed to the latter half of the molten pool 2a. Inserted in contact. The welded part in the figure shows the state of the steady period and the crater period. However, during the steady period, no current is passed through the filler wire 1b, and the welding torch WT moves at the welding speed. In contrast, during the crater period, a current is passed through the filler wire 1b, and the welding torch WT is in a stopped state. Both are the same in that the consumable electrode arc 3a is generated and the filler wire 1b is fed in contact with the molten pool 2a.

  A welding voltage Vww is applied between the welding wire 1a and the base material 2, and a welding current Iww is conducted in the consumable electrode arc 3a. In the figure, the welding direction is the left direction. A molten pool 2a is formed by the preceding consumable electrode arc 3a. A filler wire welding voltage Vwf is applied between the filler wire 1b and the base material 2, and a filler wire welding current Iwf is applied. During the steady period, since the output of the filler wire welding power source PSF is stopped, Vwf = 0V and Iwf = 0A. The filler wire 1b is inserted in contact with the latter half of the molten pool 2a, and is melted by heat from the molten pool 2a. The filler wire 1b is fed outside the consumable electrode arc 3a. This is to prevent the filler wire 1b from being directly melted by the consumable electrode arc 3a as described above. The advancing angle of the welding wire 1a is in the range of about 0 to 30 °, and in the same figure, it is a case of a straightness (0 °). The advance angle of the filler wire 1b is in the range of 20 to 50 °. That is, the filler wire 1b is inserted diagonally forward.

  The welding wire welding power source PSW is a power source for energizing the welding current Iww by applying the welding voltage Vww between the welding wire 1a and the base material 2 via the welding wire power supply tip 4a. From the welding wire welding power source PSW, a welding wire feeding control signal Wc is sent to the welding wire feeding motor WM, and the welding wire feeding speed Ws is controlled. When the welding voltage Vww is applied from the welding wire power supply PSW via the welding wire power supply tip 4a, the welding wire 1a is set to the + side. The welding power source PSW for welding wire is a power source having constant voltage characteristics as usual. Therefore, the value of the welding current Iww is determined by the welding wire feed speed Ws.

  The filler wire welding power source PSF applies a filler wire welding current Iwf by applying a filler wire welding voltage Vwf between the filler wire 1b and the base material 2 via the filler wire power supply tip 4b. It is a power supply. A filler wire feed control signal Fc is sent from the filler wire welding power source PSF to the filler wire feed motor FM to control the filler wire feed speed Fs. When the filler wire welding voltage Vwf is applied from the filler wire welding power source PSF via the filler wire power supply tip 4b, the filler wire 1b is set to the + side. The filler wire welding power source PSF is a power source having a constant current characteristic in order to control the value of the filler wire welding current Iwf to a predetermined value.

  The robot controller RC outputs an activation signal On and a crater period signal Tcs to the welding wire welding power source PSW and the filler wire welding power source PSF. The start signal On is at a high level during the steady period and the crater period, and controls the output and feeding of the welding power source. When the welding torch WT reaches the welding start position, the activation signal On becomes High level, the welding wire welding power supply PSW is started, the welding wire 1a is started, and welding in a steady period is started. Is done. At the same time, feeding of the filler wire 1b is started. When welding torch WT reaches the crater processing position (welding end position), crater period signal Tcs is at a high level for a predetermined crater period. In response to this, the output of the welding wire welding power source PSW is continued and the consumable electrode arc 3a is generated, and the feeding speed of the welding wire 1a changes to the feeding speed for the crater period. At the same time, the output of the filler wire welding power source PSF is started and current is supplied to the filler wire 1b, and the feeding speed of the filler wire 1b changes to the feeding speed for the crater period. At this time, the filler wire 1b is fed in contact with the molten pool in a state where no arc is generated. When the activation signal On changes to the Low level, the output of the welding wire welding power source PSW is stopped, the consumable electrode arc 3a is extinguished, and the feeding of the welding wire 1a is also stopped. At the same time, the output of the filler wire welding power source PSF stops and the feeding of the filler wire 1b also stops. Thereby, welding is complete | finished. The crater period is set by a work program stored in the robot controller RC. During the crater period, the welding torch WT is in a stopped state. The robot controller RC controls the operation of a robot (not shown) according to a work program.

  FIG. 2 is a block diagram of a welding wire welding power source PSW that constitutes the welding apparatus described above with reference to FIG. 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 three-phase 200 V, performs output control such as inverter control according to a drive signal Dv described later, and outputs a welding voltage Vww and a welding current Iww. Although not shown, the power supply main circuit PM includes a primary rectifier circuit that rectifies commercial power, a capacitor that smoothes the rectified direct current, an inverter circuit that converts the smoothed direct current into high frequency alternating current, and high frequency alternating current An inverter transformer that steps down the voltage to a voltage value suitable for arc welding, 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 1a is fed while being fed through the welding wire feeding tip 4a by the rotation of the welding wire feeding roll 5a coupled to the welding wire feeding motor WM, and is consumed between the base metal 2 and the welding wire 1a. An electrode arc 3a is generated. The structure of the welding torch is as shown in FIG. 1 described above, but is shown here in a simplified manner.

  The voltage detection circuit VD detects the welding voltage Vww and outputs a voltage detection signal Vd. The voltage average value calculation circuit VAV averages (smooths) the voltage detection signal Vd by passing it through a low-pass filter (cutoff frequency of about 1 to 10 Hz), and outputs a voltage average value signal Vav.

  The steady period welding voltage setting circuit VSR outputs a predetermined steady period welding voltage setting signal Vsr. The crater period welding voltage setting circuit VCR outputs a predetermined crater period welding voltage setting signal Vcr. The voltage switching circuit SV receives the steady period welding voltage setting signal Vsr, the crater period welding voltage setting signal Vcr and the crater period signal Tcs from the robot controller RC, and the crater period signal Tcs is at a low level ( The steady-state welding voltage setting signal Vsr is output as the welding voltage setting signal Vr, and the crater-period welding voltage setting signal Vcr is output as the welding voltage setting signal Vr at the high level (crater period). . The voltage error amplification circuit EV amplifies an error between the welding voltage setting signal Vr and the voltage average value signal Vav, and outputs a voltage error amplification signal Ev. With this circuit, the welding power source becomes a power source having a constant voltage characteristic. The drive circuit DV receives the voltage error amplification signal Ev and the activation signal On from the robot controller RC, and when the activation signal On is at a high level (activation) (steady period + crater period), the voltage error amplification signal. Pulse width modulation control is performed based on Ev, and a drive signal Dv for driving the inverter circuit in the power supply main circuit is output. Thereby, welding power supply PSW for welding wires is output during a steady period and a crater period.

  The steady period welding wire feed speed setting circuit WSR outputs a predetermined steady period welding wire feed speed setting signal Wsr. The crater period welding wire feed speed setting circuit WCR outputs a crater period welding wire feed speed setting signal Wcr. The feed switching circuit SW receives the above-mentioned steady period welding wire feed speed setting signal Wsr, the above crater period welding wire feed speed setting signal Wcr, and the crater period signal Tcs from the robot controller RC as inputs. When the period signal Tcs is at the Low level (steady period), the welding wire feed speed setting signal Wsr for the steady period is output as the welding wire feed speed setting signal Wr. When the period signal Tcs is at the High level (crater period), the crater period welding is performed. The wire feed speed setting signal Wcr is output as the welding wire feed speed setting signal Wr. The welding wire feed control circuit WC receives the welding wire feed speed setting signal Wr and the start signal On from the robot controller RC, and when the start signal On is at a high level (start), the welding wire feed speed is set. A welding wire feeding control signal Wc for feeding the welding wire 1a at a feeding speed determined by the setting signal Wr is output to the welding wire feeding motor WM.

  FIG. 3 is a block diagram of a filler wire welding power source PSF constituting the welding apparatus described above with reference to FIG. Hereinafter, each block will be described with reference to FIG.

  The power supply main circuit PM inputs a commercial power supply (not shown) such as a three-phase 200V, performs output control such as inverter control according to a drive signal Dv described later, and outputs a filler wire welding voltage Vwf and a filler wire welding current Iwf. To do. Although not shown, the power supply main circuit PM includes a primary rectifier circuit that rectifies commercial power, a capacitor that smoothes the rectified direct current, an inverter circuit that converts the smoothed direct current into high frequency alternating current, and high frequency alternating current An inverter transformer that steps down the voltage to a voltage value suitable for arc welding, a secondary rectifier circuit that rectifies the stepped-down high-frequency alternating current, and a reactor that smoothes the rectified direct current. The filler wire 1b is fed so as to come into contact with the molten pool while being fed through the filler wire feeding chip 4b by the rotation of the filler wire feeding roll 5b coupled to the filler wire feeding motor FM. During the steady period, the filler wire 1b is fed in contact with the molten pool in a state where the filler wire welding voltage Vwf = 0V and the filler wire welding current Iwf = 0A. On the other hand, during the crater period, the filler wire 1b is fed in contact with the molten pool while a predetermined value of filler wire welding current Iwf is energized. The structure of the welding torch is as shown in FIG. 1 described above, but is shown here in a simplified manner.

  The current detection circuit ID detects the filler wire welding current Iwf and outputs a current detection signal Id. Filler wire welding current setting circuit IFR outputs a predetermined filler wire welding current setting signal Ifr. The current error amplification circuit EI amplifies an error between the filler wire welding current setting signal Ifr and the current detection signal Id, and outputs a current error amplification signal Ei. With this circuit, the welding power source becomes a power source with constant current characteristics. The drive circuit DV receives the current error amplification signal Ei, the activation signal On and the crater period signal Tcs from the robot controller RC, the activation signal On is at a high level (activation), and the crater period signal Tcs is High. When it is at the level (crater period), pulse width modulation control is performed based on the current error amplification signal Ei, and a drive signal Dv for driving the inverter circuit in the power supply main circuit is output. Thereby, the filler wire welding power source PSF is output during the crater period, and the output is stopped during the steady period.

  The regular period filler wire feed speed setting circuit FSR outputs a predetermined steady period filler wire feed speed setting signal Fsr. The crater period filler wire feed speed setting circuit FCR outputs a crater period filler wire feed speed setting signal Fcr. The feed switching circuit SW receives the above-described steady period filler wire feed speed setting signal Fsr, the above crater period filler wire feed speed setting signal Fcr, and the crater period signal Tcs from the robot controller RC as inputs. When the period signal Tcs is at the low level (steady period), the filler wire feed speed setting signal Fsr for the steady period is output as the filler wire feed speed setting signal Fr. When the period signal Tcs is at the high level (crater period), the filler for the crater period The wire feed speed setting signal Fcr is output as the filler wire feed speed setting signal Fr. The filler wire feed control circuit FC receives the filler wire feed speed setting signal Fr and the start signal On from the robot controller RC, and when the start signal On is at a high level (startup), the filler wire feed speed is set. A filler wire feed control signal Fc for feeding the filler wire 1b at a feed speed determined by the setting signal Fr is output to the filler wire feed motor FM.

  FIG. 4 is a timing chart of each signal in FIGS. 1 to 3 for describing the two-wire welding crater control method according to the embodiment of the present invention. (A) shows the time change of the start signal On, (B) shows the time change of the crater period signal Tcs, (C) shows the time change of the welding voltage Vww, (D) ) Shows the time change of the welding wire feed speed Ws, FIG. 8E shows the time change of the welding current Iww, FIG. 8F shows the time change of the filler wire welding voltage Vwf, and FIG. ) Shows the change over time of the filler wire feed speed Fs, and FIG. 9H shows the change over time of the filler wire welding current Iwf. Hereinafter, a description will be given with reference to FIG.

  In the figure, the period before the time t1 is a steady period, and the welding torch WT performs steady welding as will be described later while moving along the welding line at a predetermined welding speed. The period from time t1 to t2 is a predetermined crater period Tc, and the crater process is performed as described later in a state where the welding torch WT is stopped. The crater period Tc is set to about 0.3 to 3.0 seconds depending on the joint shape, the type of the welding wire, the material of the base material, and the like. There is a period during which anti-stick processing is performed for a short time of about 50 ms after time t2, but this anti-stick processing is omitted here because it is the same as in the prior art.

(1) Steady period before time t1 During the steady period before time t1, the welding torch WT moves along the weld line at a predetermined welding speed. During the steady period, the activation signal On is at a high level (activation) as shown in FIG. 9A, and the crater period signal Tcs is at a low level (steady period) as shown in FIG. It has become. Since the start signal On is at the high level and the crater period signal Tcs is at the low level, the welding wire welding power source PSW sets the steady period welding voltage setting signal Vsr as shown in FIG. The welding voltage Vww having the obtained value is output. Since the start signal On is at the high level and the crater period signal Tcs is at the low level, the welding wire feed speed Ws is set to the steady period welding wire feed speed setting signal Wsr as shown in FIG. The value set by. As shown in FIG. 5E, the welding current Iww for energizing the welding wire 1a has a value corresponding to the welding wire feed speed Ws. That is, during the steady period, a consumable electrode arc 3 a to which the welding voltage Vww is applied and the welding current Iww is energized is generated between the welding wire 1 a and the base material 2. On the other hand, since the activation signal On is at the high level and the crater period signal Tcs is at the low level during the steady period, the output from the filler wire welding power source PSF is stopped. Therefore, as shown in FIG. 5F, the filler wire welding voltage Vwf is 0V, and as shown in FIG. 5H, the filler wire welding current Iwf is 0A. Since the start signal On is at the high level and the crater period signal Tcs is at the low level, the filler wire feed speed Fs is the filler wire feed speed setting signal Fsr for the steady period as shown in FIG. The value set by. That is, the filler wire 1b is fed in a state in which no arc is generated and the filler wire welding current Iwf is in contact with the latter half of the molten pool 2a without energization. The filler wire feed speed Fs during the steady period is set to about 10 to 30% of the welding wire feed speed Ws. The value of the welding voltage Vww during the steady period (the value of the welding voltage setting signal Vsr for the steady period) is set so that the consumable electrode arc 3a is stably generated corresponding to the welding wire feed speed Ws.

(2) Crater period Tc
When the welding torch WT reaches the crater processing position (welding end position) at time t1, the movement is stopped, and the crater period Tc is reached during a predetermined period of time t1 to t2. During the crater period Tc, the activation signal On is at a high level as shown in FIG. 9A, and the crater period signal Tcs is at a high level as shown in FIG. Since the start signal On is at the high level and the crater period signal Tcs is at the high level, the welding wire welding power source PSW sets the crater period welding voltage setting signal Vcr as shown in FIG. The welding voltage Vww having the obtained value is output. Since the activation signal On is at the high level and the crater period signal Tcs is at the high level, the welding wire feed speed Ws is the crater period welding wire feed speed setting signal Wcr as shown in FIG. Is set to a value that is slower than the stationary period. As shown in FIG. 5E, the welding current Iww for energizing the welding wire 1a has a value corresponding to the welding wire feed speed Ws. That is, during the crater period Tc, the welding voltage Vww for the crater period is applied, the welding current Iww for the crater period is energized, and the consumable electrode arc 3a for the crater period is interposed between the welding wire 1a and the base material 2. It has occurred. On the other hand, since the start signal On is at the high level and the crater period signal Tcs is at the high level, the filler wire welding voltage Vwf is output from the filler wire welding power source PSF as shown in FIG. The Since the start signal On is at the high level and the crater period signal Tcs is at the high level, the filler wire feed speed Fs is the crater period filler wire feed speed setting signal as shown in FIG. The value is set by Fcr, and the speed is slower than the steady period. As shown in FIG. 5H, the filler wire welding current Iwf having a value set by the filler wire welding current setting signal Ifr is energized. In other words, during the crater period Tc, the filler wire 1b is supplied with the filler wire welding current Iwf and is fed in contact with the molten pool without generating an arc. Therefore, during the crater period Tc, the crater process is performed by the consumable electrode arc 3a for the crater period and the insertion of the filler wire 1a through which a current is flowing. The biggest difference between the steady period and the crater period Tc is whether or not current is supplied to the filler wire 1b. The value of the filler wire welding current Iwf is set to a value at which the filler wire 1b during the crater period Tc is melted stably while maintaining the contact state with the molten pool. The filler wire welding current Iwf is set to an appropriate value according to the filler wire feed speed Fs, the filler wire material, the diameter, etc., and is in the range of about 50 to 300A. The filler wire welding voltage Vwf is a value determined by the negative state between the filler wire 1b and the base material 2, and since the filler wire 1b and the base material 2 are in contact with each other, the filler wire welding voltage Vwf is a very small value of about 1V or less. It becomes. Further, in order to prevent an arc from being generated between the filler wire 1b and the base material 2 when the filler wire 1b is transiently brought into a non-contact state with the base material 2, the filler wire in an unloaded state is used. The filler wire welding power source PSF is controlled so that the welding voltage Vwf (no-load voltage value) is about 5 V or less at which no arc is generated. The welding wire feed speed Ws during the crater period Tc is about 40 to 70% during the steady period. The filler wire feeding speed Fs during the crater period Tc is about 20 to 50% of the welding wire feeding speed Ws during the crater period Tc. Therefore, the welding wire feed speed Ws during the crater period Tc is slower than during the steady period. The filler wire feed speed Fs during the crater period Tc is slower than the steady period. Furthermore, the filler wire feed speed Fs during the crater period Tc is slower than the welding wire feed speed Ws during the crater period Tc. The value of the welding voltage Vww during the crater period Tc (the value of the crater period welding voltage setting signal Vcr) is set so that the arc 3a is stably generated corresponding to the welding wire feed speed Ws.

  When the crater period Tc ends at the time t2, the anti-stick process period is omitted as described above, so that the activation signal On becomes the low level (stop) as shown in FIG. As shown in FIG. 5B, the crater period signal Tcs is at a low level. Since the start signal On becomes the Low level, the output from the welding wire welding power source PSW is stopped, and the feeding of the welding wire 1a is also stopped. Similarly, since the activation signal On becomes the Low level, the output from the filler wire welding power source PSF is stopped, and the feeding of the filler wire 1b is also stopped. As a result, the consumable electrode arc 3a is extinguished. Thereby, welding is complete | finished.

  In the present embodiment, the welding wire 1a and the filler wire 1b are arranged so that the filler wire 1b does not feed the consumable electrode arc 3a. For this reason, as described above, in the prior art, when the value of the welding current Iww for energizing the consumable electrode arc 3a during the crater period decreases, the temperature of the molten pool also decreases, so the filler wire 1b can be inserted. I couldn't. In contrast, in the present embodiment, when the crater period starts, the filler wire 1b is supplied with a predetermined filler wire welding current Iwf to assist the melting of the filler wire 1b. The filler wire 1b during the steady period was not melted directly by the consumable electrode arc 3a, but was melted by receiving heat from the molten pool. For this reason, the cooling effect of the molten pool was great. Compared with this, since the temperature of the filler wire 1b during the crater period Tc is increased by the supply of the filler wire welding current Iwf, the cooling effect of the molten pool is reduced. However, since the filler wire 1b cannot be melted if there is no temperature increase due to the energization of the filler wire welding current Iwf, this embodiment takes a good balance between the cooling action of the molten pool and the melting of the filler wire 1b. Will be.

  According to the above-described embodiment, during the crater period, a crater process is performed by supplying current to the filler wire in a state where an arc between the welding wire and the base material is generated. As a result, in crater processing for narrow gap joints by 2-wire welding, the molten pool during the crater period is efficiently cooled by inserting the filler wire preheated by energization of the current, and the filler wire is completely Since it can fuse | melt, it can suppress that a crack generate | occur | produces in a crater part.

DESCRIPTION OF SYMBOLS 1a Welding wire 1b Filler wire 2 Base material 2a Weld pool 3a Consumable electrode arc 4a Welding wire feeding tip 4b Filling wire feeding tip 5a Welding wire feeding roll 5b Filler wire feeding roll DV Drive circuit Dv Drive signal EV Voltage Error amplification circuit Ev Voltage error amplification signal EI Current error amplification circuit Ei Current error amplification signal FC Filler wire feed control circuit Fc Filler wire feed control signal FCR Filler wire feed speed setting circuit for crater period Fcr Filler wire feed for crater period Feed speed setting signal FM Filler wire feed motor Fr Filler wire feed speed setting signal Fs Filler wire feed speed FSR Filler wire feed speed setting circuit Fsr for steady period Filler wire feed speed setting signal ID Current detection Circuit Id Current detection signal IFR Filler Wire Welding Current Setting Circuit Ifr Filler Wire Welding Current Setting Signal Iwf Filler Wire Welding Current Iww Welding Current On Start Signal PM Power Supply Main Circuit PSF Filler Wire Welding Power Supply PSW Welding Wire Welding Power Supply RC Robot Controller SV Voltage Switching Circuit SW Feed switching circuit Tc Crater period Tcs Crater period signal VAV Voltage average value calculation circuit Vav Voltage average value signal VCR Crater period welding voltage setting circuit Vcr Crater period welding voltage setting signal VD Voltage detection circuit Vd Voltage detection signal VSR For steady period Welding voltage setting circuit Vsr Welding voltage setting signal Vr Welding voltage setting signal Vwf Filler wire welding voltage Vww Welding voltage WC Welding wire feed control circuit Wc Welding wire feed control signal WCR Welding wire feed rate setting circuit for crater period Wcr Crater Welding wire feed speed setting signal WM welding wire feed motor Wr welding wire feed speed setting signal Ws welding wire feed speed WSR welding wire feed speed setting circuit Wsr for steady period welding wire feed speed for steady period Setting signal WT Welding torch

Claims (2)

During the steady period, in the two-wire welding crater control method of generating an arc between the welding wire and the base material and feeding the filler wire in contact with the molten pool formed by the arc,
During the crater period, a crater process is performed by passing a current through the filler wire in a state where the arc is generated.
A two-wire welding crater control method characterized by the above. The feeding speed of the welding wire during the crater period is made slower than the feeding speed during the steady period, and the feeding speed of the filler wire during the crater period is made slower than the feeding speed during the steady period. And, the feeding speed of the filler wire during the crater period is made slower than the feeding speed of the welding wire during the crater period,
The crater control method for two-wire welding according to claim 1.

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