JP2013119087A - Arc welding control method and arc welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such the problem that in a method of welding the vicinity of a welding start point in reverse polarity, in a thin sheet having a sheet thickness of about <1.0 mm, for example, when a welding object having a gap equal to or greater than its sheet thickness is welded, burn through is caused in a reverse polarity section in the vicinity of a welding start point.SOLUTION: In the arc welding control method and arc welding equipment using a welding wire as a consumable electrode, after the start of welding is directed, the contact between the welding wire and a welding object is detected, and, for a prescribed time, D.C. welding with fixed straight polarity is performed or A.C. welding in which the ratio of straight polarity is >50% is performed, and, after the prescribed time, D.C. welding with fixed reverse polarity is performed or A.C. welding in which the ratio of straight polarity is ≤50% is performed to suppress the burn through of the welding object.

Description

  The present invention performs consumable electrode type gas shielded arc welding in which an arc is generated between a consumable electrode and an object to be welded, and particularly at the start of welding, the consumable electrode is used as a negative electrode and the welding object is a positive electrode. The present invention relates to an arc welding control method and an arc welding apparatus that perform positive polarity welding or AC welding with a high positive polarity ratio.

  In a consumable electrode type gas shielded arc welding method in which an arc is generated between a consumable electrode and an object to be welded, in general, the consumable electrode is a positive electrode and the welding object is a negative electrode. Welding with However, when so-called burn-out is likely to occur, such as when thin steel plates are overlapped and the overlapping ends are welded, the consumable electrode is used as the negative electrode, the welding object is used as the positive electrode, and welding is performed with positive polarity. Sometimes.

  As described above, the consumable electrode type gas shielded arc welding method in which welding is performed with positive polarity can greatly expand the gap tolerance of the thin steel plate.

  In general, the condition that the burn-out easily occurs is a thin plate with a gap.

  When there is a gap, a molten pool that bridges both objects to be welded is formed, and an arc is generated on the molten pool, so that welding can be performed without melting even if there is a gap. it can. In other words, if a molten pool that bridges between the objects to be welded can be formed, gap correspondence is possible.

  However, in a portion where a molten pool at the start of welding is not formed, welding heat input is concentrated on one of the objects to be welded.

  Further, in the case of positive polarity, since the fusion is insufficient in the bead near the welding start point, a fusion failure occurs, and a method of performing welding with reverse polarity at the start of welding is known (for example, Patent Document 1 and Patents). Reference 2).

Japanese Patent Publication No.62-19267 Japanese Patent Publication No. 3-49665

  For example, in the method of performing welding with a welding output having a reverse polarity in the vicinity of the welding start point as described in Patent Document 1 or Patent Document 2, in a thin plate having a thickness of less than about 1.0 mm, for example, the gap is greater than the plate thickness. When welding an empty welding object, the amount of melting of the wire is small due to the reverse polarity in the reverse polarity section near the welding start point, and the droplets (melting pool) of the wire do not bridge between the welding objects. Since welding heat input concentrates on the welding object, there is a problem that burn-out occurs.

  In order to solve the above problems, an arc welding control method of the present invention is an arc welding control method using a welding wire as a consumable electrode, and after instructing the start of welding, the welding wire and the welding object are contacted. DC welding with constant positive polarity is performed for a predetermined time after detection, or AC welding with a positive polarity ratio greater than 50% is performed, and DC welding with constant reverse polarity is performed after the predetermined time. Alternatively, AC welding with a positive polarity ratio of 50% or less is performed.

  The arc welding control method of the present invention is an arc welding control method in which welding is performed using a welding robot using a welding wire as a consumable electrode and equipped with a welding torch, which is taught to start welding. While the welding torch is moved from the welding start point to the predetermined welding point taught to switch the control of the welding output, DC welding with a constant positive polarity is performed, or the positive polarity ratio is AC welding greater than 50% is performed, and when the movement of the welding torch passes the predetermined welding point, DC welding with a constant reverse polarity is performed, or AC welding with a positive polarity ratio of 50% or less is performed. is there.

  Further, in addition to the above, the arc welding control method of the present invention includes a predetermined cycle for feeding the welding wire in the forward direction in which the welding wire is fed in the direction of the object to be welded and in the reverse direction in which the forward feeding is performed in the opposite direction. And periodically changing with a predetermined amplitude.

  Further, the arc welding apparatus according to the present invention is an arc which starts an arc by bringing the wire into contact with the welding object in a state where a voltage is applied between the wire which is a consumable electrode and the welding object during the arc start period. A welding apparatus, comprising: a welding current detection unit that detects a welding current; a contact detection unit that detects contact between the wire and the welding object based on an output of the welding current detection unit; and the contact detection unit A counter unit that counts an elapsed time from the time when the wire and the object to be welded contact each other based on the signal, and a signal that switches the control of the welding output when a predetermined time elapses based on the signal from the counter unit. A control switching control unit for outputting, and a control switching switching unit for switching the welding output based on a signal from the control switching control unit, and instructing the start of welding After detecting the contact between the welding wire and the welding object after the predetermined time, perform DC welding with a constant positive polarity, or perform AC welding with a positive polarity ratio of more than 50%, After the predetermined time, DC welding with a constant reverse polarity is performed, or AC welding with a positive polarity ratio of 50% or less is performed.

  Further, the arc welding apparatus according to the present invention is an arc which starts an arc by bringing the wire into contact with the welding object in a state where a voltage is applied between the wire which is a consumable electrode and the welding object during the arc start period. A welding apparatus comprising a welding robot having a welding torch, a teaching unit for teaching a welding point on a welding path, and an instruction program taught using the operation program of the welding robot and the teaching unit. A storage unit for storing and a robot control unit for controlling the welding robot based on the operation program are taught to switch control of welding output from a welding start point taught to start welding. While the welding torch is moved to a predetermined welding point, DC welding with constant positive polarity is performed, or the positive polarity ratio is 5 % AC welding is performed, and when the welding torch moves past the predetermined welding point, DC welding with a constant reverse polarity is performed, or AC welding with a positive polarity ratio of 50% or less is performed. .

  In addition to the above, the arc welding apparatus of the present invention further includes a wire feeding unit that controls the feeding of the wire, and the feeding of the wire in the direction of the welding target and the normal feeding are performed. Is a periodic change with a predetermined period and a predetermined amplitude in reverse transmission performed in the reverse direction.

  As described above, according to the present invention, DC welding with constant positive polarity is performed at the start of welding, or reverse polarity is used at the start of welding by performing AC welding with a positive polarity ratio of greater than 50%. Compared to the welding amount can be increased and the welding objects can be bridged by wire droplets (molten pool). This makes it difficult for the objects to be welded and the gap tolerance to be high. Is possible.

The figure which shows schematic structure of the arc welding apparatus in Embodiment 1 of this invention. The figure which shows the time change of the welding current in the case of performing DC welding with the positive polarity constant until the predetermined time elapses, and thereafter performing DC welding with the constant reverse polarity until the predetermined time elapses in the first embodiment of the present invention. The time change of the control switching signal in Embodiment 1 of the present invention and the time change of the welding current in the case of performing DC welding with a constant positive polarity until the predetermined time elapses and thereafter performing AC welding with a positive polarity ratio of 50% or less. Illustration The time change of the control current in the first embodiment of the present invention and the time change of the welding current in the case of performing the AC welding with the positive polarity ratio higher than 50% until the predetermined time elapses and thereafter performing the DC welding with the constant reverse polarity. Illustration Welding current when AC welding with a positive polarity ratio higher than 50% is performed until the time change of the control switching signal and a predetermined time elapses in Embodiment 1 of the present invention, and thereafter AC welding with a positive polarity ratio of 50% or less is performed. Of change over time The figure which shows schematic structure of the arc welding apparatus in Embodiment 2 of this invention. The figure which shows the time change of the wire feeding speed in Embodiment 3 of this invention.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating a schematic configuration of an arc welding apparatus according to the first embodiment. FIG. 2 is a diagram showing the time change of the control current in the first embodiment and the time change of the welding current when DC welding with a constant positive polarity is performed until a predetermined time elapses and thereafter DC welding with a constant reverse polarity is performed. It is. FIG. 3 shows the welding current time in the case of performing DC welding with a constant positive polarity until the predetermined time elapses with the time change of the control switching signal in the first embodiment, and thereafter performing AC welding with a positive polarity ratio of 50% or less. It is a figure which shows a change. FIG. 4 shows the welding current time in the case where AC welding with a positive polarity ratio higher than 50% is performed until a predetermined time elapses, and thereafter DC welding with a constant reverse polarity is performed until a predetermined time elapses in the first embodiment. It is a figure which shows a change. FIG. 5 shows a case in which AC welding with a positive polarity ratio higher than 50% is performed until the time change of the control switching signal and a predetermined time elapse in the first embodiment, and thereafter AC welding with a positive polarity ratio of 50% or less is performed. It is a figure which shows the time change of welding current.

  In FIG. 1, the arc welding apparatus mainly includes a welding power supply unit 16 that supplies power between a wire 12 that is a consumable electrode and a welding object 15, a welding torch 13, and a wire feed that feeds the wire 12. It is composed of a supply unit 11.

  The welding torch 13 is attached to, for example, a welding robot (not shown), and welding is performed by the welding robot. Alternatively, the welding torch 13 is held by an operator, for example, and welding is performed by the operator.

  In the welding power source 16, the power input from the input power source 1 that outputs AC power is rectified by the primary rectification unit 2, converted to AC by the switching unit 3, stepped down by the transformer 4, and reduced by the secondary rectification unit 5 and Rectified by DCL (inductance) 6 and applied between the wire 12 and the welding object 15. And welding arc 14 generate | occur | produces between the wire 12 and the welding target object 15, and welding is performed.

  Further, the welding power source unit 16 detects the contact between the wire 12 and the welding object 15 and the contact based on the output of the welding current detection unit 7 that detects the welding current and the welding current detection unit 7. The counter unit 8 that counts the elapsed time from the time point, and the output of the counter unit 8 are input, and the control of the welding output is switched after a predetermined time has elapsed since the contact between the wire 12 and the welding object 15 was detected. A control switching control unit 9 that outputs a signal, a control switching switching unit 10 that switches the control of the welding output based on the output of the control switching control unit 9, and a setting unit 17 for setting welding conditions and the like are provided.

  The counter unit 8 is a wire that is generated first after the start of welding is instructed by operating a torch switch (not shown) provided on the welding torch 13 or by executing an operation program of a welding robot. The contact between the welding object 12 and the welding object 15 is detected and the time is counted. Further, the setting unit 17 sets the welding current set for performing welding, the set welding voltage set for performing welding, the feeding speed of the wire 12, the type of shield gas, the material of the wire 12, This is for setting the diameter of the wire 12 and a welding method such as pulse welding.

  In addition, each component which comprises the welding power supply part 16 may each be comprised independently as needed, and you may make it comprise combining a some component part.

  Next, an example of control switching at the time of arc start of the arc welding apparatus will be described with reference to FIGS. 1 and 2.

  In FIG. 1, for example, when an operator grips the welding torch 13 to perform welding, a welding activation signal is turned on by operating an activation switch (not shown) provided on the welding torch 13. The wire feeding unit 11 inputs a signal indicating that the welding activation signal is turned on, and starts feeding the wire 12 toward the welding object 15. At this time, a no-load voltage is applied between the wire 12 and the welding object 15 by the welding power source unit 16.

  When the wire 12 contacts the welding object 15 with no load voltage applied, a welding current also flows in the welding power source 16 via the wire 12 and the welding object 15, and this welding current is detected by the welding current detection unit. 7 is detected.

  If the welding current is detected at time T1 shown in FIG. 2, the polarity switching signal output from the control switching control unit 9 is turned on at time T1 as shown in FIG. The welding current having a constant positive polarity is output from the portion 16.

  In addition, if the counter part 8 receives the signal which shows having detected the welding current from the welding current detection part 7, it will measure the elapsed time from the time of detecting a welding current. Further, the control switching control unit 9 calculates and holds a predetermined time that is a determination reference value for the passage of time based on the input from the setting unit 17. Then, the control switching control unit 9 receives a signal indicating the elapsed time from the counter unit 8 and compares it with the predetermined time held. When the elapsed time input from the counter unit 8 reaches a predetermined time, the control switching control unit 9 switches the welding output control, that is, the control switching signal is OFF, as indicated by a time point T2 in FIG. Is output to the control switching unit 10. Then, the control of the welding output is switched by the operation of the control switching unit 10, and a welding current having a constant reverse polarity is output from the welding power source unit 16. Note that the control switching unit 10 includes, for example, a full bridge circuit composed of a plurality of switching elements.

  Further, the predetermined time (period from time T1 to time T2) is, for example, about 50 ms to 2000 ms. This time may be set using the setting unit 17 as a fixed value obtained from an experiment or the like. As described above, the set welding current, the set welding voltage, the wire set by the setting unit 17 may be used. It may be a value determined by the control switching control unit 9 based on the feeding speed, shield gas type, wire material, wire diameter, welding method, and the like.

  As described above, DC welding with constant positive polarity is performed for a predetermined time (period from time T1 to time T2) after the start of welding is instructed and the wire 12 and the welding object 15 come into contact with each other. When a predetermined time elapses, DC welding with a constant reverse polarity is performed.

  In this way, when the welding object 15 has the same plate thickness as compared with the case where the reverse polarity DC welding is performed, the positive polarity constant DC welding is performed for a predetermined time after starting welding. Since the heat input to the object to be welded is less and the wire 12 is likely to melt, the feeding amount of the wire 12 can be increased and the welding amount is increased accordingly. can do. That is, since the welding amount is large, the two welding objects 15 can be reliably bridged by the droplets (melting pool) of the wire 12 at the start of welding, and the welding objects 15 are prevented from being burned out. Can do. And after predetermined time, the welding of appropriate penetration can be performed by performing DC welding with constant reverse polarity. That is, DC welding with constant positive polarity for a predetermined time is control for suppressing welding of the welding object 15 by bridging between the welding objects 15 with droplets (molten pool) at the start of welding.

  The welding control after the predetermined time may be AC welding with a positive polarity ratio of 50% or less as shown in FIG. 3 instead of DC welding with constant reverse polarity as shown in FIG. Then, the control of FIG. 2 may be performed or the control of FIG. 3 may be performed so as to suit the welding conditions such as the plate thickness and material of the welding object 15. In order to obtain deep penetration, it is desirable to perform DC welding with a constant reverse polarity as shown in FIG. Further, regarding AC welding with a positive polarity ratio of 50% or less shown in FIG. 3, the penetration can be adjusted by changing the positive polarity ratio.

  Next, an example in which AC welding with a high positive polarity ratio is performed for a predetermined time (period from time T1 to time T2) will be described with reference to FIG. Since the basic operation is the same as that described with reference to FIG. 2, only differences from FIG. 2 will be described. 2 is different from FIG. 2 in that DC welding with a constant positive polarity is not performed during a predetermined time as shown in FIG. 2, but AC welding with a high positive polarity ratio is performed during a predetermined time as shown in FIG. It is a point to do.

  When the welding current detector 7 detects the welding current that flows due to the contact between the wire 12 and the welding object 15 at the time T1 shown in FIG. 4 after the welding start instruction is given, as shown in FIG. At time T1, the control switching signal is turned ON, and the welding power supply unit 16 outputs an alternating current having a high positive polarity ratio, for example, a positive polarity ratio larger than 50%.

  In addition, if the counter part 8 receives the signal which shows having detected the welding current from the welding current detection part 7, it will measure the elapsed time from the time of detecting a welding current. The control switching control unit 9 calculates and holds a predetermined time as a determination reference value for the passage of time based on the input from the setting unit 17. Then, the control switching control unit 9 receives a signal indicating the elapsed time from the counter unit 8 and compares it with the predetermined time held. When the elapsed time input from the counter unit 8 reaches a predetermined time, the control switching control unit 9 turns off the signal for switching the control of the welding output, that is, the polarity switching signal is turned off as shown at time T2 in FIG. Is output to the control switching unit 10. Then, the control of the welding output is switched by the operation of the control switching switching unit 10, and a welding output with a constant reverse polarity is output from the welding power source unit 16.

  As described above, the positive polarity ratio is larger than 50% during a predetermined time (period from the time T1 to the time T2) after the start of welding is instructed and the wire 12 and the welding object 15 come into contact with each other. AC welding is performed, and when a predetermined time elapses, DC welding with a constant reverse polarity is performed.

  In this way, during the predetermined time after starting welding, AC welding with a positive polarity ratio of greater than 50% is performed, so that the welding object 15 has the same plate thickness as compared with the case of constant reverse polarity. In this case, since the wire 12 is easier to melt in the positive polarity, the feeding amount of the wire 12 can be increased, and the welding amount of the wire 12 can be increased accordingly. That is, since the welding amount is large, the two welding objects 15 can be reliably bridged by the droplets (melting pool) of the wire 12 at the start of welding, and the welding objects 15 are prevented from being burned out. Can do. And after predetermined time, the welding of appropriate penetration can be performed by performing DC welding with constant reverse polarity. That is, in AC welding in which the positive polarity ratio at a predetermined time is greater than 50%, control for bridging the welding object 15 with a droplet (molten pool) at the start of welding to suppress the welding object 15 from being burned out. It is.

  Here, if the positive polarity ratio is high, it is possible to prevent the welding object 15 from being melted down. Therefore, it is desirable that the positive polarity ratio during a predetermined time is greater than 50%.

  In addition, regarding control during a predetermined time, whether to perform DC welding with a constant positive polarity as shown in FIG. 2 or whether to perform AC welding with a positive polarity ratio of more than 50% as shown in FIG. 4 is based on the welding conditions. To decide. In addition, when the gap between the welding objects 15 is large, it is desirable to perform DC welding with constant positive polarity as shown in FIG. In addition, regarding AC welding with a positive polarity ratio of 50% or less shown in FIG. 4, by changing the positive polarity ratio, it is possible to deal with a small gap to a large gap.

  The welding control after a predetermined time may be AC welding with a positive polarity ratio of 50% or less as shown in FIG. 5 instead of DC welding with constant reverse polarity as shown in FIG. Then, the control of FIG. 4 may be performed so as to suit the welding conditions, or the control of FIG. 5 may be performed. In order to obtain deep penetration, it is desirable to perform DC welding with a constant reverse polarity as shown in FIG. Further, regarding AC welding with a positive polarity ratio of 50% or less shown in FIG. 4, the penetration can be adjusted by changing the positive polarity ratio.

(Embodiment 2)
In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 6 is a diagram showing a schematic configuration of the arc welding apparatus in the second embodiment.

  In FIG. 6, the robot control device 18 controls the operation of the manipulator 19. The welding torch 13 is attached to the manipulator 19. In addition, the robot control device 18 stores an operation program, teaching information input by the teaching unit 20, and the like, and controls the operation of the manipulator 19 based on the information stored in the storage unit 21. A robot control unit 22 is provided. The robot control unit 22 has a function of communicating information with the welding power source unit 16 and outputs a control signal for welding output to the control switching control unit 9 of the welding power source unit 16 as will be described later. It also has a function.

  The main difference from the first embodiment is that when the manipulator 19 moves the welding torch 13 to the welding start point taught, the control switching signal is turned ON to perform welding output, and the manipulator 19 performs the welding torch 13. Is that the control output signal is turned off to switch the welding output when moving to the predetermined welding point taught. That is, the welding output is switched according to the taught point instead of the time.

  In FIG. 6, the robot control unit 22 of the robot control device 18 controls the operation of the manipulator 19 based on the operation program stored in the storage unit 21. When a command to move to the welding start point that is included in the operation program and taught by the teaching unit 20 is executed, the welding torch 13 is moved to the welding start point by controlling the operation of the manipulator 19. When the welding torch 13 is moved to the welding start point, the robot control unit 22 outputs a signal indicating that the welding torch 13 has moved to the welding start point to the control switching control unit 9. The control switching control unit 9 that has received the signal from the robot control unit 22 turns on the output polarity switching signal (corresponding to the time point T1), and the operation of the control switching switching unit 10 causes the welding power source unit 16 to display FIG. As shown in FIG. 3, a welding current having a constant positive polarity is output. Further, when the operation program is executed and the welding torch 13 moves to a predetermined welding point taught by the teaching unit 20, the robot control unit 22 causes the control switching control unit 9 to move the welding torch 13 to the predetermined welding point. The signal which shows that is output. The control switching control unit 9 that has received the signal from the robot control unit 22 turns off the output polarity switching signal (corresponding to the time T2), and the operation of the control switching switching unit 10 causes the welding power source unit 16 to display FIG. As shown in FIG. 4, a welding current having a constant reverse polarity is output.

  As described above, the welding control may be switched by the taught welding start point and the predetermined welding point. By doing in this way, like the first embodiment, the two welding objects 15 can be reliably bridged by the droplets (molten pool) of the wires 12 at the start of welding. Melting-down can be suppressed. Then, when a predetermined welding point is passed, DC welding with constant reverse polarity is performed, so that appropriate penetration welding can be performed.

  Similar to the first embodiment, the welding control may be performed by appropriately using the controls shown in FIGS. 2 to 5 based on welding conditions and the like.

  The distance from the welding start point to the predetermined welding point is, for example, about 0.5 mm to 20 mm.

  Note that not only at the start of welding but also during the welding, the control switching signal may be turned ON to perform DC welding with a constant positive polarity or AC welding with a positive polarity ratio greater than 50%. For example, if there is a large gap in the middle of the welding path, the starting point and the ending point of the gap are taught in advance, and the control switching signal is turned ON at the first point to make positive polarity DC welding or positive electrode AC welding with a sex ratio greater than 50% may be performed, and the control switching signal may be turned off at the end point to return to the welding control before the control signal was turned on. Since the gap point is relatively easy to check and easy to teach, welding control is not switched at a predetermined time as in the first embodiment, but welding is performed at the welding point as in the second embodiment. It is easier to switch the control.

(Embodiment 3)
In the third embodiment, the same parts as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the third embodiment, as shown in FIG. 7, the feeding of the wire 12 is performed in a predetermined cycle between normal feeding performed in the direction of the welding object 15 and reverse feeding performed in the direction opposite to the normal feeding. It is changed periodically with a predetermined amplitude.

  In short-circuit transfer welding in which the wire 12 is periodically forwarded and reversely fed, a short-circuit state is formed when the wire 12 is forward-fed, and when the wire 12 is fed backward, the wire 12 is pulled up so that the short-circuit state is opened and an arc state It becomes the welding method which forms. In this case, the time ratio of short circuit is as high as 30 to 50% compared to about 15 to 30% which is a ratio in the case of general short circuit transfer welding. Therefore, heat input becomes lower than general short circuit transfer welding, and it is possible to suppress the welding object 15 from being burned out. For this reason, as a welding method in which a section between a time T1 when a welding current is detected after an instruction to start welding and a time T2 after a predetermined time and when a control switching instruction is given is used as a section for suppressing burnout, By performing short-circuit transfer welding in which 12 is periodically forwarded and reversely fed, the effect of preventing burnout is further increased.

  The wire 12 may be fed in a sine wave shape as shown in FIG. 7 or a trapezoidal wave shape, and is preferably periodic.

  The arc welding control method and the arc welding apparatus of the present invention are unlikely to cause burn-off at the start of welding, have a high gap tolerance, and make it easy to adjust welding conditions. This is industrially useful as an arc welding control method and an arc welding apparatus used when there is a gap between objects.

DESCRIPTION OF SYMBOLS 1 Input power supply 2 Primary rectification part 3 Switching part 4 Transformer 5 Secondary rectification part 6 DCL (inductance)
DESCRIPTION OF SYMBOLS 7 Welding current detection part 8 Counter part 9 Control switching control part 10 Control switching switching part 11 Wire feeding part 12 Wire 13 Welding torch 14 Welding arc 15 Welding object 16 Welding power supply part 17 Setting part 18 Robot controller 19 Manipulator 20 Teaching Unit 21 Storage unit 22 Robot control unit

Claims (6)

An arc welding control method using a welding wire as a consumable electrode,
DC welding with a constant positive polarity is performed for a predetermined time after contact between the welding wire and the welding object is detected after instructing the start of welding, or AC welding with a positive polarity ratio of more than 50%. Arc welding control method in which DC welding with a constant reverse polarity or AC welding with a positive polarity ratio of 50% or less is performed after the predetermined time. An arc welding control method using a welding wire as a consumable electrode and performing welding using a welding robot equipped with a welding torch,
While the welding torch is moved from a welding start point taught to start welding to a predetermined welding point taught to switch control of welding output, DC welding with constant positive polarity is performed. Alternatively, AC welding with a positive polarity ratio of greater than 50% is performed, and when the movement of the welding torch passes the predetermined welding point, DC welding with a constant reverse polarity is performed, or the positive polarity ratio is 50%. An arc welding control method for performing the following AC welding. 3. The welding wire according to claim 1 or 2, wherein feeding of the welding wire is periodically changed at a predetermined cycle and a predetermined amplitude between a normal feed performed in the direction of the welding object and a reverse feed performed in a direction opposite to the normal feed. The arc welding control method described. In the arc start period, an arc welding apparatus that performs an arc start by bringing the wire into contact with the welding object in a state where a voltage is applied between the wire that is a consumable electrode and the welding object,
A welding current detector for detecting a welding current;
A contact detection unit that detects contact between the wire and the welding object based on an output of the welding current detection unit;
A counter unit that counts an elapsed time from the time when the wire and the welding object contact based on a signal from the contact detection unit;
A control switching control unit for outputting a signal for switching the control of the welding output when a predetermined time elapses based on a signal from the counter unit;
A control switching switching unit that switches the welding output based on a signal from the control switching control unit,
Direct current welding with positive polarity is performed for a predetermined time after contact between the welding wire and the welding object is detected after instructing the start of welding, or the positive polarity ratio is greater than 50%. An arc welding apparatus that performs AC welding and performs DC welding with a constant reverse polarity after the predetermined time or AC welding with a positive polarity ratio of 50% or less. In the arc start period, an arc welding apparatus that performs an arc start by bringing the wire into contact with the welding object in a state where a voltage is applied between the wire that is a consumable electrode and the welding object,
A welding robot with a welding torch;
A teaching unit for teaching a welding point on the welding path;
A storage unit for storing teaching points taught using the welding robot operation program and the teaching unit;
A robot controller that controls the welding robot based on the operation program,
While the welding torch is moved from a welding start point taught to start welding to a predetermined welding point taught to switch control of welding output, DC welding with constant positive polarity is performed. Alternatively, AC welding with a positive polarity ratio of greater than 50% is performed, and when the movement of the welding torch passes the predetermined welding point, DC welding with a constant reverse polarity is performed, or the positive polarity ratio is 50%. Arc welding equipment that performs the following AC welding. A wire feeding unit for controlling the feeding of the wire, and feeding the wire in a predetermined cycle and a predetermined period in a forward feeding performed in the direction of the welding object and a reverse feeding performed in a direction opposite to the normal feeding. The arc welding apparatus according to claim 4 or 5, wherein the arc welding apparatus is periodically changed with an amplitude of.

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