JP5154056B2 - Welding wire retract control method and welding wire retract control device - Google Patents

Description

  The present invention relates to a welding wire retract control method and a welding wire retract control device.

  As one of arc start control methods for arc welding, a wire retract start is known in which an arc is generated by pulling up a welding wire from a workpiece (base material) with a wire feeding device (Patent Document 1). In the wire retract start, first, the welding torch held by the manipulator is moved to the welding start position taught in advance by the movement of the manipulator, and the torch is stopped at the welding start position. Next, the wire feeding motor is rotated forward to advance and feed the welding wire to the workpiece. Subsequently, when it is determined that the welding wire has come into contact with the workpiece, the wire feeding motor is reversely rotated to feed the welding wire backward from the workpiece, and at the same time, an initial current having a small current value is energized. Next, when the welding wire is separated from the work piece by reverse feeding and an initial arc is generated, the welding wire is fed forward again at a steady feeding speed, and a steady welding current is supplied and stopped simultaneously. By switching the welding torch to the movement in the welding direction taught in advance, a steady arc transition is performed.

  On the other hand, when the distance of the welding wire feeding path is long, or when the feeding path is complicated and there are many curves, the feeding resistance of the welding wire may increase, and the welding wire may not be fed stably. In such a case, an auxiliary feeding device is installed on the welding wire feeding path in addition to the main feeding device to improve the feeding performance of the welding wire. This auxiliary feeding device is realized by a simple control system that uses an inexpensive induction motor or the like as a feeding motor, does not control the speed of the welding wire, and only assists in feeding the wire with a constant torque ( Patent Document 2).

Here, with reference to FIG.6 and FIG.5, the outline | summary of the arc welding apparatus provided with the said main feeder and auxiliary feeder and the conventional wire retract start method are demonstrated.
As shown in FIG. 6, the arc welding apparatus is based on teaching data input via a teach pendant used for teaching a manipulator 120 having a welding torch 110, the movement of the manipulator 120 in advance, and the like. The robot control device RC for controlling the reproduction operation of the manipulator 120, the welding power source device PS, and the like are provided.

  A push-pull method is applied to the feeding system of the welding wire 140. The feeding system is provided in the vicinity of a main feeding device 130 as a pull side feeding device mounted on the arm of the upper arm portion of the manipulator 120 and a wire reel (not shown) that winds the welding wire 140, and is provided on the push side. It consists of an auxiliary feeding device 150 as a feeding device. The welding wire 140 fed out from the wire reel is fed to the welding torch 110 via a conduit 160A extending from the auxiliary feeding device 150 to the manipulator 120 and a conduit 160B moving on the manipulator 120.

  The main feeding device 130 of the feeding system in such an arc welding apparatus controls the speed of feeding the welding wire 140, and the auxiliary feeding device 150 on the push side has a function of simply pushing the wire with a constant force by torque control. Demonstrate.

  The main feeding device 130 includes a feeding roll 132 and a pressure roll 134 in order to clamp the welding wire 140. The feed roll 132 is driven by a motor 136 such as an AC servo motor so as to be able to rotate forward and reverse. Further, the pressure roll 134 is driven to rotate along with the welding wire 140 that is moved by the rotation of the feed roll 132 and is urged toward the feed roll 132 by an elastic member (not shown). In addition, the auxiliary feeding device 150 includes a feeding roll 152 and a pressure roll 154 for clamping the welding wire 140. The feed roll 152 is driven to be normally rotated by a feed motor 156 made of an induction motor or the like. The pressure roll 154 is driven to rotate along with the welding wire 140 that is moved by the rotation of the feed roll 152, and is attached to the feed roll 152 side by an elastic member (not shown) provided in the pressure release mechanism 154a. And is driven by a drive source 158 such as a solenoid so as to be separated from the feed roll 152 via a pressure release mechanism 154a.

  FIG. 5 is a timing chart when a conventional wire retract start is performed by the arc welding apparatus of FIG. 6 described above. In the figure, (A) is the gas control signal Gc, (B) is the welding command signal St, (C) is the on / off of the motor 136 of the main feeding device 130, and (D) is the auxiliary feeding device 150. (E) shows the retract control signal Rm of the main feeder 130, and (F) shows the time change of the auxiliary feeder retract signal Rs. In FIG. 5, (G) shows the wire feed speed command Fc, (H) shows the torque of the main feed device 130, and (I) shows the time change of the welding current Iw. Hereinafter, a description will be given with reference to FIG.

(1) Preflow time Tp between times t1 and t2
At time t1, when a valve opening command is input from the robot controller RC to the welding power source PS, the gas control signal Gc (High) is sent from the welding power source PS to the gas electromagnetic valve 112 as shown in FIG. Level) is output, the gas solenoid valve 112 is opened, and the ejection of shield gas is started.

  Before the time t1 and during the preflow time Tp, the feeding motor 156 of the auxiliary feeding device 150 is turned on and is rotating forward (forward feeding rotation), but the motor 136 of the main feeding device 130 is rotating. In this state, the torque is set so that the welding wire 140 cannot be fed forward, so that the welding wire 140 is not fed forward.

(2) Initial feeding time Tf at times t2 to t3
When a predetermined preflow time Tp elapses at time t2, a welding command signal St (High level) for starting welding is output from the robot control device RC to the welding power source device PS. In response to this, the welding power supply device PS outputs a wire feed speed command Fc, turns on the motor 136 of the main feed apparatus 130, and controls the speed so as to be the initial wire feed speed Fi. As a result, the welding wire 140 is fed forward to the workpiece 200 (base material) at the initial wire feeding speed Fi, and the distance between the welding wire tip and the workpiece 200 is gradually shortened. When the wire feed speed command Fc is a positive value, forward feed is performed, and when the wire feed speed command Fc is negative, backward feed is performed. Further, the welding power source device PS forms a constant current characteristic or a drooping characteristic, and a no-load voltage is applied as a welding voltage although not shown.

(3) Time Te from time t3 to t4
At time t3, when the tip of the wire comes into contact with the workpiece 200 (base material), the distance between the tip of the wire and the workpiece 200 becomes zero, and the welding voltage changes to a short-circuit voltage value of about several volts. As shown in I), the welding current Iw is an initial current Ii having a small current value of several tens of A.

  At this time, the welding power source device PS detects that the welding voltage has changed below a predetermined reference voltage value, and determines contact between the welding wire 140 and the workpiece 200. As a result of this determination, the welding power source device PS has the wire feed speed command Fc at a negative reverse feed speed Fr as shown in FIG.

  It should be noted that, in the initial period of time Te from time t3 to t4, a delay time during which the motor 136 reverses from normal rotation to reverse rotation and the play of the welding wire 140 in the welding torch 110 are necessary for backward feeding. The time (contact time) during which the wire tip remains in contact with the workpiece 200 is included depending on the delay time. This contact time varies depending on the type of the wire feed motor, the length of the welding torch, etc., but is usually about 50 ms.

  In addition, the determination result of the contact between the welding wire 140 and the workpiece 200 by the welding power supply device PS is transmitted to the robot control device RC, and the robot control device RC responds to the determination result with the auxiliary feeding device retract signal Rs ( High level) is output to excite the drive source 158, and the pressure roll 154 is opened via the pressure release mechanism 154a against an elastic member (not shown).

  When the welding wire 140 retreats and the tip of the welding wire is separated from the workpiece 200, an initial arc in which the initial current Ii is energized is generated. When the initial arc is generated, the welding voltage becomes an arc voltage value of several tens of volts and exceeds the reference voltage value. From this time point, the backward feeding is continued for a predetermined delay time. The reason for providing the delay time is to prevent the contact state from being brought into contact again because the arc length is very short when switching from backward feed to re-forward feed immediately after the initial arc occurs.

(4) Period after time t4 When the above delay time has elapsed at time t4, as shown in FIG. 5G, the steady feeding speed setting in which the value of the wire feeding speed command Fc is a positive value. The value Fsc is reached, and the re-feeding of the welding wire 140 is started.

  Further, when the welding power supply device PS notifies that the delay time has elapsed, the robot control device RC outputs an auxiliary feeding device retract signal Rs (Low level) to demagnetize the drive source 158, as shown in the figure. The pressure roll 154 is urged toward the feed roll 152 via the pressure release mechanism 154a by the urging force of the elastic member that does not.

  At the same time, the welding voltage is controlled by the welding power source device PS so as to coincide with a predetermined voltage setting value, and a steady welding current Ic corresponding to the steady feeding speed is applied. Then, a smooth transition is made from the initial arc generation state to the steady arc state of the steady arc length.

In Patent Document 3, a torque transmission coupling is described.
JP 2002-178145 A JP 2004-167514 A JP 2001-262310 A

  By the way, when performing a wire retract start using an AC servo motor having high controllability and responsiveness as the main feeding device 130 and using an inexpensive induction motor or the like as the auxiliary feeding device 150, the wire retraction control is being performed. In the period from time t3 to t4 in FIG. 5, a conflict occurs between the backward feeding by the main feeding device 130 and the forward feeding by the auxiliary feeding device 150.

  Also in the above-described conventional example (Patent Document 2), by applying a retract signal (auxiliary feeding device retract signal Rs) to the auxiliary feeding device 150, the pressure of the feeding roll 152 is mechanically released, and the main feeding is performed. The welding wire 140 can be retracted only by the feeding device 130.

  However, the retract time during the wire retract start is normally about several tens of msec, and in the conventional technique in which the pressure roll 154 is opened by a mechanical mechanism, the pressure of the feed roll 152 of the auxiliary feeding device 150 is increased. The auxiliary feeding device 150 may perform forward feeding during this time because the opening is not in time.

When the backward feeding by the main feeding device and the forward feeding by the auxiliary feeding device compete, the welding wire cannot be backwardly fed by a desired length at a desired speed, and the following phenomenon occurs.
First, there is a problem that the welding wire and the work piece (base material) are not separated from each other, and it takes time until an arc is generated. In the worst case, there is a problem that an arc does not occur within a specified time and an arc start failure occurs. Further, there is a problem that a re-short circuit occurs immediately after the initial arc is generated, so that sputtering occurs or a desired arc length is not achieved.

  These may be avoided by adjusting the feeding torque of the auxiliary feeding device. In this case, although the torque of the auxiliary feeding device is weaker than the backward feeding torque of the main feeding device, it is adjusted to a torque that can be assisted so that no feeding failure occurs during forward feeding of the welding wire. However, in the auxiliary feeding device, the feeding torque is mechanically fixed to a fixed value that is adjusted and set in advance, and cannot be changed during operation. In actual welding, the position / posture of the manipulator changes greatly depending on the welding site, and the feeding path changes accordingly. For this reason, it is practically impossible to adjust the feeding torque of the auxiliary feeding device so as to be the above-described optimum at all the welding locations.

  As described above, the problem that the backward feeding by the main feeding device and the forward feeding by the auxiliary feeding device compete with each other has been described in the case of the wire retract start, but during the retry process that is performed when the arc does not occur This also occurs in the case of a retract or a retract by an operator's operation.

  The object of the present invention is to use the auxiliary feeding device that is realized by a simple control system using an inexpensive induction motor or the like, and perform the reverse feeding by the main feeding device and the auxiliary feeding device. It is an object of the present invention to provide a welding wire retract control method and a welding wire retract control device capable of performing wire retract without competing forward feeding.

In order to solve the above problems, the invention according to claim 1 includes a main feeding device including a first feeding motor that controls the speed of welding wire feeding, a second feeding motor, and a second feeding motor. Using an auxiliary feeding device that applies a feeding force against the frictional resistance generated in the conduit by controlling the torque of the feeding motor output, the welding wire is push-pull fed to the welding torch, and the main In a method for controlling the retracting of a welding wire in which the welding wire is retracted by reverse feeding by a feeding device, the second feeding motor of the auxiliary feeding device is stopped and during the retracting period before the retracting is started. The gist of the control method for retracting the welding wire is characterized in that control is performed to continuously stop the second feed motor .

  In the present invention, the predetermined time includes the total time of the retraction and the time elapsed after the peak time of the torque when the first feeding motor of the main feeding device is reversely fed (reverse feeding) at the start of the retraction. It is the purpose.

According to a second aspect of the present invention, there is provided a main feeding device including a first feeding motor that controls the speed of welding wire feeding, a second feeding motor, and a conduit that performs torque control on the output of the second feeding motor. Auxiliary feeding device that applies a feeding force against the frictional resistance generated in the welding wire to the welding wire is controlled, and the welding wire is pushed and pulled to the welding torch, and welding is performed by controlling the reverse feeding by the main feeding device. In a welding wire retract control device for retracting a wire,
Control means for stopping the second feeding motor of the auxiliary feeding device before starting the retracting and continuously stopping the second feeding motor until the retracting period is provided. The gist of the welding wire retract control device is as follows.

According to a third aspect of the present invention, in the second aspect of the present invention, the period before the retraction includes a preflow time in which the ejection of the shield gas is started, and the control means controls the second feeding motor of the auxiliary feeding device. Stopping from the start time of the preflow time and continuing until the retraction period.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the period before the retraction includes a preflow time in which the ejection of the shield gas is started, and the control means applies a feed to the welding wire of the main feeding device. The first feeding motor is turned on for forward feeding at the time when the preflow time ends, and thereafter, the backward feeding control is performed during the retracting time, and the forward feeding is performed after the retracting, or The control means, after the peak of the torque of the first feeding motor that has been turned on for forward feeding at the time when the preflow time ends, the second feeding of the auxiliary feeding device. In addition to stopping the motor, the control means further determines a time from when the first feeding motor starts the backward feeding by the backward feeding control until the torque peak of the first feeding motor is passed. As serial predetermined time, the second feed motor is stopped, then, characterized by on-operation of the second feed motor auxiliary feeder.

According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the control means is configured by a single control means.

  According to the method of claim 1, an auxiliary feeding device that is realized by a simple control system that uses a cheap induction motor or the like and does not perform wire speed control but only assists wire feeding with a constant torque. When performing retraction using the wire retraction, the backward feeding by the main feeding device and the forward feeding by the auxiliary feeding device do not compete with each other.

Further, since the turn off the feed motor of the auxiliary feeder, the until the torque decreases there is a time difference, if Stop Stops the feed motor from retracting earlier, the torque of the feed motor Retraction can be performed with sufficient reduction or with the feed motor completely stopped.

According to the invention of claim 3 , since there is a time difference from when the feeding motor of the auxiliary feeding device is turned off until the torque decreases, the stop of the feeding motor is started before the reflow. If it stops from the time, the torque of the feeding motor is sufficiently lowered, or the retraction can be performed with the feeding motor completely stopped.

According to the invention of claim 4 , the second feeding motor of the auxiliary feeding device is stopped after the torque peak in the first feeding motor of the main feeding device that has been turned on at the time when the preflow time has ended. Thus, it is possible to prevent a shortage of torque of the first feeding motor at the start of forward feeding. Further, the second feed motor is stopped by setting the time from when the first feed motor starts the reverse feed by the reverse feed control to the time when the torque peak of the first feed motor passes the predetermined time, After that, by turning on the second feeding motor of the auxiliary feeding device, it is possible to prevent a shortage of torque of the first feeding motor when the first feeding motor is switched to forward feeding after the retract has elapsed. .

According to the fifth aspect of the present invention, the control means is constituted by a single control means, so that the control means includes a control means for individually controlling the main feeding device and the auxiliary feeding device. Thus, there is no time difference in the control of both the main feeding device and the auxiliary feeding device, and there is no delay due to the control of each device. That is, in the case where control means for individually controlling the main feeding device and the auxiliary feeding device is provided, each control means performs processing such as synchronization by performing communication between the two control means. As a result, a time difference may occur in the control of each device, but this is not the case when each device is controlled by a single control means.

(Reference example)
First , after describing a reference example with reference to FIGS. 1 and 2, an embodiment of the present invention will be described. Since the configuration of the embodiment is the same in hardware as the reference example, the reference numerals assigned to the same configuration as the reference example are used.
Welding wire retract control device of the reference example are those in the welding power supply PS included in the arc welding apparatus having a main feeder及beauty auxiliary feeder embodying, FIGS Reference Example Will be described with reference to FIG.

  As shown in FIG. 1, the arc welding apparatus includes a manipulator 20 having a welding torch 10, teaching input via a teach pendant (not shown) used for teaching the movement of the manipulator 20 in advance. A robot control device RC for controlling the reproduction operation of the manipulator 20 based on the data, a welding power supply device PS, and the like are provided.

  A push-pull method is applied to the feeding system of the welding wire 40. The feeding system is provided in the vicinity of a main feeding device 30 as a pull-side feeding device mounted on the arm of the upper arm portion of the manipulator 20 and a wire reel (not shown) that winds the welding wire 40, and is provided on the push side. It consists of an auxiliary feeding device 50 as a feeding device. The welding wire 40 fed out from the wire reel is fed to the welding torch 10 via a conduit 60A extending from the auxiliary feeding device 50 to the manipulator 20 and a conduit 60B moving on the manipulator 20.

  The main feeding device 30 of the feeding system in such an arc welding apparatus controls the speed of feeding of the welding wire 40, and the auxiliary feeding device 50 on the push side has a function of simply pushing the wire with a constant force by torque control. Demonstrate.

The main feeding device 30 includes a feeding roll 32 and a pressure roll 34 in order to clamp the welding wire 40. The feed roll 32 is driven by a motor 36 so as to be able to rotate forward and reverse. The motor 36 is an AC servo motor with high control accuracy and excellent responsiveness, and a feed roll attached to the welding wire 40 so as to pull out the welding wire 40 at a constant speed so as to keep the amount of protrusion from the contact tip 10a. 32 is driven. The motor 36 corresponds to a first feed motor in the embodiment described later . The pressure roll 34 is driven to rotate along with the welding wire 40 that is moved by the rotation of the feed roll 32 and is urged toward the feed roll 32 by an elastic member (not shown).

The auxiliary feeding device 50 cooperates with the feeding roll 52, the feeding motor 56, the torque transmission coupling 56 a that transmits the torque of the feeding motor 56 to the feeding roll 52, and the feeding roll 52. A pressure roll 54 for clamping the welding wire 40 is provided. The torque of the feeding motor 56 gives a force against the frictional resistance to the welding wire 40 moving through the conduits 60A and 60B via the torque transmission coupling 56a and the feeding roll 52. Take up most of the power you need. The feeding roll 52 is driven by a feeding motor 56 so as to be normally rotated. The feed motor 56 is constituted by an induction motor in this reference example . The feed motor 56 corresponds to a second feed motor in the embodiment described later .

The motor used in the auxiliary feeding device 50 is not limited to the induction motor, but is cheaper than the AC servo motor used in the above-described main feeding device 30 such as a DC motor, a synchronous motor, or a step motor. motor is used (hereinafter, the i Sunda including transfection motor of the motor as "induction motor or the like"). Incidentally, since an example of the structure of the torque transmission coupling (torque limiter) is described in Patent Document 3, detailed description thereof is omitted here.

  Further, the pressure roll 54 is driven to rotate along with the welding wire 40 that is moved by the rotation of the feed roll 52, and is attached to the feed roll 52 side by an elastic member (not shown) provided in the pressure release mechanism 54a. And is driven by a drive source 58 such as a solenoid so as to be separated from the feed roll 52 via a pressure release mechanism 54a.

In this reference example , the pressure release mechanism 54a of the auxiliary feeding device 50 is operated by the auxiliary feeding device retract signal Rs output from the welding power source device PS when an operation instruction is given by an external operation input by the operator. This is for the pressure release operation. As a result, the welding wire 40 can be retracted for a longer time than the retract time at the time of wire retract start, which will be described later.

In the conventional configuration shown in FIG. 6, various controls of the auxiliary feeding device 150 (on / off control of the motor 156 and de-excitation control of the drive source 158) are performed by the robot controller RC. On the other hand, in this reference example , since the welding power supply device PS controls all of the main feeding device 30 and the auxiliary feeding device 50, the motor 36 of the main feeding device 30 and the feeding motor 56 of the auxiliary feeding device 50 are used. The drive source 58 is electrically connected to the welding power source PS. The welding power source device PS includes a CPU (central processing unit), a computer having a ROM, a RAM, and the like (not shown). The welding power supply device PS corresponds to a control unit.

Now, in this reference example , a method of wire retract start will be described with reference to FIG.
FIG. 2 is a timing chart when a wire retract start is performed by the arc welding apparatus of FIG. 1 described above. In FIG. 2, (A) to (I) are the same as (A) to (I) in FIG.

(1) Preflow time Tp between times t1 and t2
At time t1, when a valve opening command is input from the robot controller RC to the welding power source PS to the welding power source PS, the gas electromagnetic valve 12 is sent from the welding power source PS to the welding power source PS in FIG. The gas control signal Gc (High level) is output to the gas solenoid valve 12, the gas solenoid valve 12 is opened, and the ejection of shield gas is started.

  Before the time t1 and during the preflow time Tp, the feeding motor 56 of the auxiliary feeding device 50 is turned on to perform normal rotation (forward feeding rotation), but the motor 36 of the main feeding device 30 In this state, the welding wire 40 is not fed forward because the torque is set so that the welding wire 40 cannot feed forward.

  Here, the preflow time is the time from when the shield gas is ejected until the motor 36 of the main feeding device 30 is turned on. Therefore, the end time of the preflow time coincides with the time when the motor 36 of the main feeding device 30 is turned on.

(2) Initial feeding time Tf at times t2 to t3
When a predetermined preflow time Tp elapses at time t2, a welding command signal St (High level) for starting welding is output from the robot control device RC to the welding power source device PS. In response to this, the welding power source apparatus PS outputs a wire feed speed command Fc, turns on the motor 36 of the main feed apparatus 30, and controls the speed so as to be the initial wire feed speed Fi. As a result, the welding wire 40 is fed forward to the workpiece 100 (base material) at the initial wire feeding speed Fi, and the distance between the welding wire tip and the workpiece 100 is gradually shortened. When the wire feed speed command Fc is a positive value, forward feed is performed, and when the wire feed speed command Fc is negative, backward feed is performed. Further, the welding power source device PS forms a constant current characteristic or a drooping characteristic, and a no-load voltage is applied as a welding voltage although not shown.

(3) Time Te from time t3 to t4
At time t3, when the tip of the wire comes into contact with the workpiece 100 (base material), the distance between the tip of the wire and the workpiece 100 becomes zero, and the welding voltage changes to a short-circuit voltage value of about several volts. As shown in (I), the welding current Iw is an initial current Ii having a small current value of several tens of A.

  At this time, welding power supply apparatus PS detects that the welding voltage has changed to a predetermined reference voltage value or less, and determines contact between welding wire 40 and workpiece 100 to be welded. As a result of this determination, the welding power source device PS sets the wire feed speed command Fc to a negative reverse feed speed Fr as shown in FIG.

  It should be noted that in the initial period of time Te from time t3 to t4, it is necessary to reversely feed the delay time for the motor 36 to reverse from normal rotation to reverse rotation and the play of the welding wire 40 in the welding torch 10. The time (contact time) during which the wire tip remains in contact with the workpiece 100 is included depending on the delay time. This contact time varies depending on the type of the wire feed motor, the length of the welding torch, etc., but is usually about 50 ms.

  Further, based on the determination result of the contact between the welding wire 40 and the workpiece 100 by the welding power source device PS, the welding power source device PS turns off the feeding motor 56 of the auxiliary feeding device 50 and stops it.

  Then, when the welding wire tip moves away from the workpiece 100 due to the retreat of the welding wire 40, an initial arc in which the initial current Ii is energized is generated. When the initial arc is generated, the welding voltage becomes an arc voltage value of several tens of volts and exceeds the reference voltage value. From this time point, the backward feeding is continued for a predetermined delay time. The reason for providing the delay time is to prevent the contact state from being brought into contact again because the arc length is very short when switching from backward feed to re-forward feed immediately after the initial arc occurs.

(4) Period after time t4 At the time t4, when the above delay time elapses, the welding wire 40 is retracted and pulled up to have a desired arc length. Therefore, as shown in FIG. The welding power source device PS sets the value of the wire feed speed command Fc to a steady feed speed set value Fsc that is a positive value, and starts re-feeding the welding wire 40.

  At the same time as the above delay time elapses, the welding power source device PS turns on the feeding motor 56 of the auxiliary feeding device 50 to give the feeding roll 52 rotation for forward feeding. At this time, the pressure roll 54 remains pressed and urged by an elastic member (not shown).

  At the same time, the welding voltage is controlled by the welding power source device PS so as to coincide with a predetermined voltage setting value, and a steady welding current Ic corresponding to the steady feeding speed is applied. Then, a smooth transition is made from the initial arc generation state to the steady arc state of the steady arc length.

Thus, the main feeding device 30 is controlled by the welding power source device PS.
It is possible to prevent competition between the backward feeding of the welding wire 40 and the forward feeding of the auxiliary feeding device 50.

Now, the reference example has the following characteristics.

( 1 ) The welding power supply device PS of the present reference example includes a main feeding device 30 including a motor 36 (first feeding motor) that controls the speed of feeding the welding wire 40, and a feeding motor 56 (second feeding motor). And the auxiliary feeding device 50 that applies a feeding force against the frictional resistance generated in the conduits 60A and 60B to the welding wire.

  As a result, compared to the case where the control unit for individually controlling the main feeding device 30 and the auxiliary feeding device 50 is provided, there is a time difference in controlling both the main feeding device 30 and the auxiliary feeding device 50. No delay occurs due to the control of each device.

( 2 ) In this reference example , the retracting method and the welding power source device PS described in the above (1) were configured so that the wire retract start was possible.
As a result, in this reference example , the welding wire 40 and the workpiece 100 (base material) are not separated from each other, and therefore there is no problem that it takes time until the arc is generated. Further, since no arc is generated within a specified time, there is no arc start failure. In addition, according to this reference example , it is possible to prevent a short-circuit from occurring immediately after the initial arc is generated or a spatter from being generated, so that the desired arc length is not achieved.

(First embodiment)
Since the hardware configuration of the first embodiment is the same as the hardware configuration of the reference example, the same components are denoted by the same reference numerals and description thereof is omitted.
In the reference example , there is a time difference from when the feeding motor 56 of the auxiliary feeding device 50 is turned off at time t3 until the torque of the auxiliary feeding device 50 decreases. Against this, in the present embodiment, as shown in FIG. 3, the welding power supply PS is a timing of starting the pre-flow time t1, turn off the feed motor 56 of the auxiliary feeder 50.

  In this case, since there is a time difference from when the feeding motor 56 of the auxiliary feeding device 50 is turned off until the torque decreases, if the stopping of the feeding motor 56 is stopped before the retraction, Retraction can be performed in a state where the torque of the feed motor 56 is sufficiently reduced or the feed motor 56 is completely stopped.

  Note that the feeding motor 56 of the auxiliary feeding device 50 may be stopped at any time during the preflow time or at any time between the time when the preflow time ends and the retract start time.

(Second Embodiment)
Since the hardware configuration of the second embodiment is the same as the hardware configuration of the reference example, the same components are denoted by the same reference numerals and description thereof is omitted.
In the above-described reference example of FIG. 2 and the embodiment of FIG. 3, steady feeding is performed at the start of feeding of the welding wire 40 (time t2) or when switching from backward feeding to forward feeding (time t4). A feeding torque larger than that at the time of feeding is required. However, at time t4 in FIG. 2 and FIG. 3, there is a time difference from when the feeding motor 56 of the auxiliary feeding device 50 is turned on until the actually required torque is generated. The required torque may not be reached.

  In the embodiment of FIG. 3, at time t2, since the feeding motor 56 of the auxiliary feeding device 50 is not turned on, torque for forward feeding is generated on the auxiliary feeding device 50 side. Absent.

Therefore, in the second embodiment, in the welding power source device PS, the torque of the main feeding device 30 (torque of the motor 36) is monitored based on the motor current, and after the torque peak at the start of forward movement has passed, The feeding motor 56 of the auxiliary feeding device 50 is turned on / off (see FIG. 4). Specifically, as shown in FIG. 4, the feeding motor 56 of the auxiliary feeding device 50 is turned off at time t2 ′ to prevent torque shortage at the start of forward feeding, and from time t3 ′ or time t3 ′ in advance. After the set delay time elapses, the feeding motor 56 of the auxiliary feeding device 50 is turned on early to prevent torque shortage at the time of switching to forward feeding at time t4.

In addition, you may change embodiment of this invention as follows.
A modification of the second embodiment will be described.
Arc welder, the position and posture of the manipulator 20 is changed for each weld site, bending also varies the feed path. Thereby, the feeding resistance of the welding wire 40 also changes. Therefore, in the second embodiment, it is determined by monitoring the torque of the main feeding device 30 how much the torque of the auxiliary feeding device 50 and the feeding resistance are offset at the position / posture to be welded. You may make it do. Specifically, the welding power supply device PS determines the torque (torque of the motor 36) applied to the main feeding device 30 during the feeding stop period of the welding wire 40 until the time t1 or the time t2 based on the motor current. Keep monitoring.

  When the torque detected during this time is a certain torque or more in the backward feeding direction of the welding wire 40, the torque of the auxiliary feeding device 50 is strong, and the welding wire 40 is welded by the main feeding device 30. Is stopped from being fed forward. In this state, since it is difficult to perform the backward feeding of the welding wire 40 in the main feeding device 30, the welding power source device PS performs the off control of the feeding motor 56 of the auxiliary feeding device 50. Otherwise, the on / off control of the feeding motor 56 of the auxiliary feeding device 50 may not be performed.

The on / off timing of the feeding motor 56 of the auxiliary feeding device 50 may simply have a predetermined delay time from each event from time t1 to time t4 .

  ○ The feeding motor 56 of the auxiliary feeding device 50 is turned off to perform the reverse feeding of the welding wire 40 not necessarily during the wire retract start. For example, a retry process performed when an arc does not occur It may be a retract inside or a retract by an operator's operation. In this case, the retract signal may not be connected to the auxiliary feeding device 50, and the pressure releasing mechanism 54a of the pressure roll 54 of the auxiliary feeding device 50 may not be provided.

  In each of the above embodiments, the main power supply device 30 and the auxiliary power supply device 50 are turned on / off by the welding power supply device PS. Instead of this, each signal of on / off, retract on / off, wire feed speed command Fc of the motor 36 of the main feeding device 30, each of motor on / off, retract on / off of the auxiliary feeding device 50 Both signals may be output from the robot controller RC.

  In the embodiment described with reference to FIG. 3, the feeding motor of the auxiliary feeding device is stopped from the time when the preflow is started. However, the preflow time is ended from any time during the preflow time. The feeding motor of the auxiliary feeding device may be stopped at any time between the time and the retract start time.

The schematic of the arc welding apparatus and feeding system of a reference example . The timing chart of a reference example . The timing chart of 1st Embodiment. The timing chart of 2nd Embodiment. Conventional timing chart. Schematic of a conventional arc welding apparatus and a feeding system.

Explanation of symbols

10 ... welding torch, 20 ... manipulator, 30 ... main feeding device,
32 ... feeding roll, 36 ... motor (first feeding motor), 40 ... welding wire,
50 ... auxiliary feeding device, 52 ... feeding roll, 54 ... pressure roll,
54a ... Pressure release mechanism, 56 ... Feed motor (second feed motor),
60A, 60B ... Conduit, PS ... Welding power supply (control means).

Claims (5)

A main feeding device including a first feeding motor for controlling the speed of welding wire feeding, and a friction resistance generated in the conduit including a second feeding motor and torque-controlling the output of the second feeding motor. Control of retracting the welding wire by using the auxiliary feeding device that applies the resisting feeding force to the welding wire, push-pull feeding the welding wire to the welding torch, and retracting the welding wire by reverse feeding by the main feeding device In the method
Before the retraction is started, the second feed motor of the auxiliary feeding device is stopped, and the second feed motor is continuously stopped until the retract period. Control method of welding wire retract.   A main feeding device including a first feeding motor for controlling the speed of welding wire feeding, and a friction resistance generated in the conduit including a second feeding motor and torque-controlling the output of the second feeding motor. A welding wire retract that controls an auxiliary feeding device that applies a resisting feeding force to the welding wire, push-pull feeds the welding wire to the welding torch, and retracts the welding wire by controlling reverse feeding by the main feeding device. In the control device,
  Control means for stopping the second feeding motor of the auxiliary feeding device before starting the retracting and continuously stopping the second feeding motor until the retracting period is provided. Welding wire retract control device.   The period before the retraction includes the preflow time when the shielding gas starts to blow,
  3. The welding wire according to claim 2, wherein the control means stops the second feeding motor of the auxiliary feeding device from the start time of the preflow time and continues until the retracting period. Retract control device.   The period before the retraction includes the preflow time when the shielding gas starts to blow,
  The control means includes
  The first feeding motor that applies feed to the welding wire of the main feeding device is turned on for forward feeding at the time when the preflow time ends, and then the backward feeding control is performed during the retract time. Then, after the retract has passed,
  The control means includes
  The first feeding motor that has been turned on for forward feeding at the time when the preflow time has ended, after the torque peak has passed, stops the second feeding motor of the auxiliary feeding device,
  Further, the control means includes
  The time from when the first feed motor starts reverse feed by the reverse feed control until the torque peak of the first feed motor is passed is set as the predetermined time, and the second feed motor is stopped. Then, the welding wire retract control device according to claim 2, wherein the second feeding motor of the auxiliary feeding device is turned on thereafter.   The welding wire retract control device according to any one of claims 2 to 4, wherein the control means is constituted by a single control means.

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