WO2020026750A1

WO2020026750A1 - Welding method by welding robot, and welding robot

Info

Publication number: WO2020026750A1
Application number: PCT/JP2019/027517
Authority: WO
Inventors: 俊英加藤; 達也天野; 準一齋藤; 真弘田代
Original assignee: 株式会社アマダホールディングス
Priority date: 2018-08-02
Filing date: 2019-07-11
Publication date: 2020-02-06
Also published as: JPWO2020026750A1; JP6727456B2

Abstract

Provided is a welding method by a welding robot (1) provided with: a wire supply device (25) for supplying a filler wire (FW); a sub-supply device (29) that is provided in the vicinity of a guide nozzle (27) for guiding the filler wire to a welding position and supplies the filler wire; and a guide tube (37) that is provided between the wire supply device and the sub-supply device and guides the filler wire, wherein both a step for controlling the wire supply device to stop operating or operate at low speed when a slight motion of the guide tube in the supply direction (F) of the filler wire is detected, and a step for returning the wire supply device to the original operation state when the return of the guide tube is detected are performed while continuously supplying the filler wire by means of the sub-supply device.

Description

Welding method and welding robot in welding robot

The present invention relates to a welding method and a welding robot in a welding robot.

レーザ A laser welding robot is an example of a welding robot. The laser welding robot includes a guide tube (flexible conduit) that guides the filler wire to a laser beam irradiation position. A guide nozzle that guides the filler wire toward the welding position is provided on the distal end side of the guide tube. Patent Documents 1 to 3 disclose related technologies.

JP-A-6-87073 Japanese Patent Application Laid-Open No. 7-24572 Japanese Patent Application Publication No. 2018-27571

In a welding robot, a guide tube (flexible conduit) connected to a wire feeding device for feeding a filler wire can follow the movement of a robot arm or the like while smoothly guiding the filler wire, and has a bending habit. It is requested that there is not. The guide tube has a triple structure including a lower winding in which a steel wire is spirally formed, a resin liner tube provided inside the lower winding, and a resin coating covering the lower winding. is there.

In the above guide tube, when the filler wire comes into contact with the inner peripheral surface of the liner tube when guiding the filler wire, the liner tube moves in the feed direction of the filler wire, and shifts between the lower winding and the liner tube. May occur. If the supply of the filler wire becomes excessive and the liner tube moves greatly, the guide tube may be damaged.

One aspect of the present invention is a wire feeding device that feeds a filler wire, and a sub feeding device that is provided near a guide nozzle that guides the filler wire to a welding position and feeds the filler wire. A welding tube provided between the wire feeding device and the sub-feeding device, and a guide tube for guiding the filler wire, the welding robot comprising: When detecting the fine movement of the guide tube, a step of controlling the driving state of the wire feeding device to stop or low-speed driving, and when detecting the return of the guide tube, the driving state of the wire feeding device is And a step of returning to the original driving state during the continuous feeding of the filler wire by the sub-feeding device.

Another aspect of the present invention is a wire feeding device that feeds a filler wire, and a sub feeding device that is provided near a guide nozzle that guides the filler wire to a welding position and feeds the filler wire. And a guide tube provided between the wire feeding device and the sub-feeding device, for guiding the filler wire, fine movement of the guide tube in the feeding direction of the filler wire, and A fine motion detector for detecting the return, and when the fine motion is detected by the fine motion detector, the driving state of the wire feeding device is stopped or controlled to a low speed drive, and the return of the guide tube is performed by the fine motion detector. And a control device for returning the driving state of the wire feeding device to the original driving state when the detection is detected.

FIG. 1 is a diagram conceptually and schematically showing the entire configuration of the welding robot according to the embodiment. FIG. 2 is a partial cross-sectional view showing the configuration of the fine movement detector. 3A and 3B are external views of the fine motion detector, wherein FIG. 3A is a side view, and FIG. 3B is a view as viewed from the direction of arrow IIIB of FIG. 4A and 4B are diagrams schematically illustrating the operation of the embodiment. FIG. 4A illustrates a case where filler wire feeding speeds of the wire feeding device and the sub feeding device are substantially equal, and FIG. The case where the feeding speed of the device is higher than the feeding speed of the sub feeding device will be described. (C) shows a state in which the fine movement of the guide tube has occurred, and (D) shows a state in which the fine movement of the guide tube has been eliminated. FIG. 5 is a flowchart illustrating the operation of the embodiment. FIG. 6 is a partial cross-sectional view schematically showing the configuration of another embodiment of the guide tube.

As shown in FIG. 1, the welding robot 1 according to the embodiment is, for example, a laser welding robot. The welding robot 1 has a base frame 3. On the base frame 3, a swivel table 5 that can be swiveled horizontally is provided. The turntable 5 can turn horizontally by appropriately controlling a servomotor (not shown). The turntable 5 supports the base end of the first arm 7 so as to be swingable in the direction of arrow A about a horizontal axis.

には At the distal end of the first arm 7, the base end of the second arm 9 is supported so as to be swingable in the direction of arrow B about a horizontal axis. The second arm 9 is rotatable around its axis in the direction of arrow C. At the distal end of the second arm 9, the base end of the third arm 13 provided with the laser processing head 11 is supported so as to be swingable in the direction of arrow D. The laser processing head 11 is provided with an end effector 15. The end effector 15 is connected via an optical fiber 17 to a laser oscillator 19 such as a fiber laser oscillator. A focusing lens 21 for focusing the laser beam LB is provided in the laser processing head 11.

The welding robot 1 is provided with a configuration for feeding the filler wire FW to the laser beam condensing position by the condensing lens 21, that is, the welding position of the work W. At an appropriate position of the welding robot 1, a wire reel 23 wound with a filler wire FW and a wire feeding device 25 for feeding the filler wire FW are provided.

The welding robot 1 is provided with a guide nozzle 27 that guides the filler wire FW fed by the wire feeding device 25 to a welding position. A sub-feeding device 29 that assists the feeding of the filler wire FW into the guide nozzle 27 is provided at a position upstream of the guide nozzle 27 and close to the guide nozzle 27.

In the casing 31 of the wire feeder 25, a plurality of pairs of pinch rollers 33 for feeding the filler wire FW are rotatably provided. A pinch roller 36 for feeding the filler wire FW to the guide nozzle 27 is rotatably provided in the casing 35 of the sub feeding device 29. The pinch roller 33 of the wire feeding device 25 and the pinch roller 36 of the sub feeding device 29 are rotationally driven by separate motors in synchronization with each other.

Between the wire feeding device 25 and the sub feeding device 29, a guide tube 37 for guiding the filler wire FW fed (sent) from the outlet of the wire feeding device 25 to the entrance of the sub feeding device 29 is provided. Is provided. That is, the wire feeding device 25 is provided on the upstream side of the guide tube 37 in the feeding direction F of the filler wire FW, and the sub-feeding device 29 is provided on the downstream side of the feeding direction F.

The pinch roller 33 of the wire feeder 25 and the pinch roller 36 of the sub feeder 29 are used to feed the filler wire FW in the wire feeder 25 and feed the filler wire FW in the sub feeder 29. They are rotated synchronously so that their speeds are equal to each other. The feed rate is the feed rate [m / min] of the filler wire FW per unit time. However, if an error in the feeding speed occurs between the wire feeding device 25 and the sub feeding device 29, the guide tube 37 may be damaged due to the following phenomenon.

That is, when the feeding speed of the wire feeding device 25 is higher than the feeding speed of the sub feeding device 29, an error in the feeding speed causes a difference between the wire feeding device 25 and the sub feeding device 29. It accumulates as the surplus length of the filler wire FW. If the length of the filler wire FW located in the guide tube 37 is excessive, the filler wire FW is bent in the guide tube 37 and presses it from the inside, and the guide tube 37 may be damaged. .

In the present embodiment, a mechanism is provided that detects that the feed speed of the filler wire FW by the wire feed device 25 is higher than the feed speed of the sub feed device 29 and prevents the guide tube 37 from being damaged. Have been.

That is, the fine movement detector 39 is provided in the casing 31 of the wire feeding device 25. The fine movement detector 39 detects the fine movement of the guide tube 37 in the feeding direction F of the filler wire FW. “Slight movement” means that the relative position or posture (such as an angle) of the guide tube 37 with respect to the wire feeding device 25 is displaced from the normal position and posture shown in FIG. A control device 41 is connected to the fine movement detector 39 as shown in FIG. The control device 41 controls the driving state of the wire feeding device 25 (hereinafter, also referred to as “driving mode”) to “stop” when detecting the slight movement of the guide tube 37, or the “low speed driving” set in advance. Is controlled. In "stop", the drive of the wire feeding device 25 is stopped for a predetermined time set in advance. The predetermined time, that is, the stop time is not particularly limited, but is, for example, 0.1 [sec]. The drive stop may be a continuous stop or an intermittent stop. “Low-speed driving” refers to driving the wire feeding device 25 so as to satisfy the following condition A. Condition A is that the feeding speed of the wire feeding device 25 is lower than the feeding speed of the sub feeding device 29 and is lower than the feeding speed of the wire feeding device 25 when "slight movement" is not detected. It is to be smaller. The control device 41 can be composed of, for example, a general-purpose microcomputer including a CPU (Central Processing Unit), a storage unit, and an input / output unit.

(2) As shown in FIG. 2, the fine movement detector 39 includes a cylindrical base member 47 which can be attached to the casing 31 of the wire feeder 25 by a fixing tool 45 such as a bolt. The base member 47 includes a flange portion 47F, and a cylindrical movable member 51 urged toward the base member 47 by an elastic member 49 such as a plurality of coil springs is provided on the flange portion 47F. The elastic member 49 is held in a compressed and deformed state by a bolt 49B screwed to the base member 47, and urges the movable member 51 toward the base member 47.

The movable member 51 is provided with a tube connector 53 for connecting the end of the guide tube 37 to the movable member 51. The tube connector 53 has, for example, a configuration similar to a collet chuck, includes a cylindrical collet 53A screwed to the movable member 51, and includes a fastener 53B such as a nut capable of tightening the collet 53A. I have.

接続 When connecting the guide tube 37 to the fine motion detector 39, the end of the guide tube 37 is inserted into the tube connector 53 and into the base member 47. Then, the end face of the guide tube 37 is adjusted to a position corresponding to the filler wire FW sent out from the pinch roller 33, and the tube connector 53 is tightened, so that the guide tube 37 is integrally connected to the movable member 51.

When the wire feeding device 25 feeds (sends) the filler wire FW into the guide tube 37, the filler wire FW contacts the inner peripheral surface of the guide tube 37 and feeds the guide tube 37 to the filler wire FW. Press in direction F. Accordingly, the movable member 51 tends to be moved in the feeding direction F by the guide tube 37. Here, when the force (thrust) for moving the movable member 51 in the feeding direction F becomes larger than the urging force of the elastic member 49, the movable member 51 moves (displaces) away from the base member 47. I do. The movable member 51 is provided with a sensor 55 for detecting that the movable member 51 has been displaced away from the base member 47. The fine movement detector 39 can detect fine movement with such a simple configuration.

The sensor 55 can be composed of an appropriate sensor such as a limit switch or a proximity sensor. As shown in FIGS. 3A and 3B, the sensors 55 may be provided around the movable member 51 at equal intervals in the circumferential direction. By the way, when the

robot arms

7, 9, and 13 operate, the filler wire FW delivered into the guide tube 37 may be twisted or bent in the guide tube 37. Then, the force applied from the filler wire FW to the inner peripheral surface of the guide tube 37 due to the torsion, bending, or the like may not be balanced in the direction orthogonal to the axis of the guide tube 37, and a bending moment may be applied to the movable member 51. In this case, the movable member 51 may be slightly inclined with respect to the base member 47. That is, the attitude (angle) of the movable member 51 with respect to the base member 47 can be changed. In the present embodiment, since the plurality of sensors 55 are provided around the movable member 51, at least one of the inclination (displacement) in which a part of the movable member 51 in the circumferential direction is separated from the base member 47 is determined. It can be detected (detected) by the sensors 55. That is, the inclination of the movable member 51 can be detected regardless of the inclination direction.

The sensor 55 may be provided on one or both of the base member 47 and the movable member 51.

When the feeding speed of the filler wire FW by the wire feeding device 25 and the sub feeding device 29 is substantially equal, as shown in FIG. 4A, the length of the filler wire FW in the guide tube 37 is not appropriate. Is maintained at a suitable length. However, when the feeding speed of the wire feeding device 25 is higher than the feeding speed of the sub feeding device 29, the length of the filler wire FW in the guide tube 37 gradually becomes longer than the length of the guide tube 37. Become.

Eventually, as shown in FIG. 4B, the filler wire FW in the guide tube 37 curves between the sub-feeding device 29 and the wire feeding device 25 to contact the inner surface of the guide tube 37. become. When the curvature is further increased, the filler wire FW presses the guide tube 37 in the feeding direction F. When the pressing force (thrust) becomes larger than the urging force of the elastic member 49, the movable member 51 is moved in the feeding direction F as shown in an exaggerated manner in FIG. That is, the movable member 51 is slightly separated from the base member 47 fixed to the casing 31.

When the movable member 51 is separated from the base member 47, for example, all of the plurality of sensors 55 are turned on to detect (detect) the separation. Note that the movable member 51 may be inclined with respect to the base member 47 such that a part of the movable member 51 in the circumferential direction is separated from the base member 47 depending on the positions and postures of the

robot arms

7, 9, and 13. Also in this case, at least one of the plurality of sensors 55 provided around the movable member 51 is turned on.

When the sensor 55 is turned on to detect the displacement of the movable member 51, the detection signal of the sensor 55 is input to the control device 41. When the detection signal is input to the control device 41, the control device 41 stops driving the wire feeding device 25 in step S1 or changes the driving state of the wire feeding device 25 in step S1, as shown in FIG. Is controlled to a preset low-speed drive.

At this time, the driving of the sub-feeding device 29 is not stopped, and the feeding of the filler wire FW is continuously performed. Therefore, the filler wire FW in the guide tube 37 is pulled from the downstream side by the sub-feeding device 29. Thereby, as shown in FIG. 4D, the bending of the filler wire FW and the contact with the guide tube 37 are eliminated, and the pressing of the guide tube 37 in the feeding direction F due to these is eliminated. For this reason, the guide tube 37 returns to the original state with respect to the wire feeding device 25, that is, the normal position and posture in which “fine movement” is not detected, and the sensor 55 is turned off. The elastic member 49 assists the guide tube 37 to return to the normal position and posture.

(4) Then, in step S2, the control device 41 determines whether or not the detection signal has been turned off. In the case of YES in step S2, the control device 41 proceeds to step S3, and returns the drive state of the wire feeding device 25 to the “original drive state”. The “original driving state” is a driving state or a driving mode when “fine movement” is not detected. For example, the feeding speed of the wire feeding device 25 and the feeding speed of the sub feeding device 29 become equal. It is such a drive mode. Then, after returning the drive state of the wire feeding device 25 to the original drive state, the control device 41 ends the process. In the case of NO in step S2, the control device 41 determines in step S4 whether a predetermined time set in advance after the start of the processing in step S1. If NO in step S4, the process returns to step S2. In the case of YES in step S4, the control device 41 notifies the operator of the occurrence of the abnormal state in step S5, and ends the process. Then, when the fine movement detection signal is input again from the sensor 55, the control device 41 restarts the process from step S1. Thereby, the control device 41 controls the driving state of the wire feeding device 25 to be stopped or low-speed driving when detecting fine movement, and drives the wire feeding device 25 when detecting return of the guide tube 37. Returning the state to the original driving state can be alternately repeated.

As described above, the control device 41 of the welding robot 1 stops driving the wire feeding device 25 while continuing the feeding of the filler wire FW by the sub feeding device 29 while the fine movement is detected. Alternatively, the driving state is controlled to low-speed driving. Then, when the fine movement is no longer detected, the driving state of the wire feeding device 25 is returned to the original driving state.

It should be noted that the wire feeder 25 and the sub feeder 25 are controlled from the time when the fine movement is detected until the time when it is no longer detected, that is, while the driving state of the wire feeder 25 is stopped or controlled to the low speed drive. The feeding speed of each of the 29 is not particularly limited as long as the above condition A is satisfied. Further, the sub-feeding device 29 may continue to feed the filler wire FW at a preset predetermined feeding speed regardless of whether the driving of the wire feeding device 25 is stopped or driven at a low speed. Thereby, even when fine movement occurs, the filler wire FW can be continuously fed to the welding position and welding can be continued.

The feeding speed of the wire feeding device 25 in low-speed driving may be set to a feeding speed obtained by multiplying the feeding speed in the original driving state by a preset reduction ratio. Here, the feed speed in the original driving state is determined according to the moving speed of the laser processing head 11 with respect to the workpiece W, that is, the welding speed [mm / min]. It is determined according to welding processing conditions such as the material, material, and shape of the weld joint.

The deceleration ratio can be set according to filler information such as the material and diameter of the filler wire FW. For example, when the material of the filler wire FW is aluminum and the diameter is 0.2 [mm], the speed reduction ratio can be set to 80 [%]. When the material of the filler wire FW is stainless steel (SUS) and the diameter is 0.3 [mm], it can be set to 50 [%]. The control device 41 may obtain the deceleration ratio from the filler information by calculation or from a map.

By making the feed speed in the original drive state multiplied by the deceleration ratio the feed rate in the low-speed drive, the feed rate in the low-speed drive should be a feed rate that matches the welding speed in the original drive state. Can be. Further, by setting the deceleration ratio at least based on the material and diameter of the filler wire FW as described above, it is possible to perform deceleration more suitable for welding processing conditions. The set deceleration ratio may be set and changed by an operator as appropriate. Thus, even when the welding processing conditions and the welding speed are changed, the operator can set the feed speed of the filler wire FW suitable for the changed conditions in a timely manner.

Further, the control device 41 of the welding robot 1 controls the driving state of the wire feeding device 25 to stop or to control the driving speed to low speed when the feeding of the filler wire FW by the sub feeding device 29 is continuously performed. And returning to the original driving state may be alternately repeated. By alternately repeating, even when there is an error in the feeding speed between the wire feeding device 25 and the sub feeding device 29, the feeding of the filler wire FW to the welding position can be continuously continued. . Note that the control device 41 may control the low-speed driving continuously after stopping the driving of the wire feeding device 25, or may control the low-speed driving continuously after stopping the driving of the wire feeding device 25. That is, the control device 41 may alternately repeat the control of the drive state of the wire feeding device 25 to stop and the control of low-speed drive. Thereby, by changing the magnitude of the tensile force applied to the filler wire FW in the guide tube 37 with time, the contact, pressing, etc. of the filler wire FW with the guide tube 37 can be more efficiently eliminated. Can be.

As described above, in the present embodiment, when the wire feeding device 25 feeds the filler wire FW, the filler wire FW comes into contact with the inner peripheral surface of the guide tube 37 and moves the guide tube 37 in the feeding direction F. , The fine movement detector 39 detects the fine movement of the guide tube 37. Then, when the fine movement of the guide tube 37 is detected, the driving of the wire feeding device 25 is stopped, or the driving state of the wire feeding device 25 is controlled to low speed driving. At this time, by continuously operating the sub-feeding device 29 provided on the guide nozzle 27 side, the filler wire FW is pulled from the downstream side, the contact with the inner peripheral surface of the guide tube 37 is eliminated, and the pushing is performed. Progress is also canceled.

Therefore, damage to the guide tube 37 due to the filler wire FW coming into contact with and pushing the inner peripheral surface of the guide tube 37 is prevented. Specifically, for example, when the filler wire FW comes into contact with the inner peripheral surface of the liner tube of the guide tube 37, the liner tube moves in the feeding direction F, and the gap between the lower winding and the liner tube is reduced. Can be prevented. Accordingly, it is possible to prevent the supply of the filler wire FW from being excessive and the liner tube from being largely moved, and the guide tube 37 from being damaged. According to the present embodiment, the welding by the welding robot can be performed satisfactorily for a long time.

The fine movement detector 39 may be provided in the wire feeding device 25 as described above. The thrust acting on the guide tube 37 in the feed direction F of the filler wire FW tends to be larger on the upstream side than on the downstream side. Since the fine movement detector 39 is provided in the wire feeding device 25 located on the upstream side of the guide tube 37, fine movement can be detected more efficiently.

In the present embodiment, a plurality of sensors 55 are provided around the movable member 51. Therefore, when at least one of the plurality of sensors 55 detects displacement in the feeding direction F, the driving state of the wire feeding device 25 is set to low-speed driving, and all of the plurality of sensors 55 move in the feeding direction F. When the displacement is detected, the driving can be stopped. As described above, by changing the drive mode of the wire feeding device 25 according to the detected form or magnitude of the displacement, the contact, pressing, and the like of the filler wire FW against the guide tube 37 are more efficiently eliminated. be able to. Note that the relationship between the number of sensors 55 that have detected the displacement and the drive mode of the wire feeding device 25 is not limited to the above. That is, when the predetermined number (for example, one) of the sensors 55 detects the displacement, the driving state of the wire feeding device 25 is set to the low-speed driving, and the number of the sensors 55 (for example, two) larger than the predetermined number is changed. The drive of the wire feeding device 25 may be stopped when it is detected.

In order to improve the strength of the guide tube 37, it is conceivable to increase the thickness of the lower winding of the guide tube 37. However, in this case, the weight of the guide tube 37 may increase, and the flexibility may decrease. Therefore, as shown in FIG. 6, the guide tube 37 is inserted into a resin tube 61 such as a nylon tube, and the outer peripheral surface of the copper pipe 57 provided integrally at both ends of the guide tube 37 and the outer surface of the tube 61. The inner peripheral surfaces at both ends may be integrally bonded with the adhesive 59.

According to the configuration of FIG. 6, the load applied to the guide tube 37 can be shared between the tube 61 and the guide tube 37, so that the tensile strength of the guide tube 37 can be improved. Therefore, damage to the guide tube 37 due to the feeding speed of the wire feeding device 25 being higher than the feeding speed of the sub feeding device 29 can be suppressed.

Although several embodiments have been described above, each embodiment is merely an example described in order to facilitate understanding of the present disclosure. The technical scope of the present disclosure is not limited to the specific technical matters disclosed in the above embodiments, but also includes various modifications, changes, and alternative technologies that can be easily derived therefrom.

This application claims priority based on Japanese Patent Application No. 2018-145965 filed on August 2, 2018, the entire contents of which are incorporated herein by reference.

1 Welding Robot 25 Wire Feeding Device 27 Guide Nozzle 29 Sub Feeding Device 37 Guide Tube 39 Fine Motion Detector 41 Controller 47 Base Member 49 Elastic Member 51 Movable Member 53 Tube Connector 55 Sensor F Feeding Direction FW Filler Wire

Claims

A wire feeding device for feeding a filler wire,
A sub-feeding device that is provided near a guide nozzle that guides the filler wire to a welding position and that feeds the filler wire,
A guide tube provided between the wire feeding device and the sub feeding device, for guiding the filler wire,
A welding method in a welding robot equipped with
When detecting the fine movement of the guide tube in the feeding direction of the filler wire, a step of controlling the driving state of the wire feeding device to stop or low-speed driving,
When detecting the return of the guide tube, a step of returning the driving state of the wire feeding device to the original driving state,
During the continuous feeding of the filler wire by the sub-feeding device.
Regardless of whether the driving state of the wire feeding device is the stop or the low-speed driving, the sub feeding device continues to feed the filler wire at a predetermined feeding speed set in advance. The welding method according to claim 1, wherein the welding is performed.
A wire feeding device for feeding a filler wire,
A sub-feeding device that is provided near a guide nozzle that guides the filler wire to a welding position and that feeds the filler wire,
A guide tube provided between the wire feeding device and the sub feeding device, for guiding the filler wire,
Fine movement of the guide tube in the feed direction of the filler wire, and a fine movement detector that detects the return of the guide tube,
When the fine movement is detected by the fine movement detector, the driving state of the wire feeding device is controlled to be stopped or low-speed driving, and when the return of the guide tube is detected by the fine movement detector, the wire feeding is controlled. A control device for returning the drive state of the device to the original drive state,
Welding robot with.
The welding robot according to claim 3, wherein the fine movement detector is provided in the wire feeding device.
The fine movement detector,
A base member attachable to a casing of the wire feeding device,
A movable member biased toward the base member by a plurality of elastic members,
A tube connector for connecting and fixing the guide tube to the movable member,
A sensor for detecting displacement of the movable member with respect to the base member,
The welding robot according to claim 3, further comprising:
The welding robot according to claim 5, wherein a plurality of the sensors are provided around the movable member.
When the predetermined number of the sensors detect the displacement, the control device sets the drive state of the wire feeding device to the low-speed drive, and when the number of the sensors greater than the predetermined number detects the displacement, The welding robot according to claim 5, wherein driving of the wire feeding device is stopped.
Regardless of whether the driving state of the wire feeding device is the stop or the low-speed driving, the control device sets the filler wire at a predetermined feeding speed set in advance. The welding robot according to any one of claims 3 to 7, wherein the welding robot is continuously supplied.
4. The control device according to claim 3, wherein the control device sets a feed speed obtained by multiplying a feed speed of the filler wire in the original drive state by a predetermined reduction ratio as a feed speed of the filler wire in the low-speed drive. 8. The welding robot according to claim 8.
The welding robot according to claim 9, wherein the speed reduction ratio is determined based on at least a material and a diameter of the filler wire.