JPH09295143A - Method for adjusting extension of welding wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity by adjusting a process of the series of extension of the wire, and moving a welding torch by a robot in a temporally duplicate manner to reduce the welding time and the movement cycle time. SOLUTION: During the welding at one welding part, a wire feeding equipment is driven forward to feed the wire in the forward direction, while a clamping equipment is in the released condition and does not interfere the feed of the wire. When the welding is completed, the wire feed equipment is stopped, and the feed of the wire to a welding torch is stopped. Then, the wire is clamped by the clamping equipment closer to the welding torch in the wire feed direction than to the wire feed equipment. The wire feed equipment is driven backward, and the wire is fed in the reverse direction, the excessive part of the wire part between the wire feed equipment and the clamping equipment is removed to optimize the wire length. Then, the reverse driving of the wire feed equipment is stopped, and reverse feed of the wire is stopped. Clamping of the wire by the clamping equipment is released to set the wire free.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of adjusting the protrusion amount of a welding wire from a welding torch in arc welding.

[0002]

2. Description of the Related Art In recent years, GMA (gas shield metal arc) welding (hereinafter simply referred to as arc welding) has been widely used for the purpose of improving productivity, improving the environment, and shortening working hours. In particular, the automation of welding by robots has become widespread, and problems specific to robot welding have also arisen. One of the problems peculiar to robot welding is the change in conduit cable path when the robot posture changes,
There is a change in the wire protrusion length from the welding torch. Japanese Unexamined Patent Publication No. 63-317262 discloses the following method as a method for suppressing a change in wire protrusion length in robot welding. First, as shown in the conventional column of FIG. 8, at the end of welding at one welding site, during the movement of the welding torch by the robot from the robot to the next welding site, the movement is stopped and the welding torch of the welding wire is removed. There is a step of adjusting the amount of protrusion. Further, the method of adjusting the protrusion length to a predetermined length (= L) is such that when it is confirmed by the work continuity that the protrusion length reaches the predetermined length and the wire hits the work, the wire feeding device is simultaneously operated. The method of stopping the forward rotation of is taken. Further, during the protrusion length adjustment, the wire is fed backward, forward, and backward (see the conventional column in FIG. 8), but the amount thereof is uniquely controlled by the timer control.

[0003]

However, the conventional wire protrusion amount adjusting method has the following problems. As shown in FIG. 8, since the robot stops while adjusting the wire protrusion amount, the cycle of welding and torch movement becomes longer,
Productivity decreases. Further, when the touch sensor method detects that the wire hits the work, when the compound 101 is formed on the surface of the molten metal sphere 100 by Si in the wire component as shown in FIG. 10, the compound is insulated. Since it is a body, even if the tip of the wire 102 comes into contact with the work 104 (ground side), conduction may not be confirmed in some cases. Therefore, the feeder may detect the conduction only when the wire continues to be fed and the wire intermediate portion 103 is bent and comes into contact with the work 104 as shown in FIGS. 11 and 12. In this case, the predetermined length L cannot be managed. Also, when the wire is fed backward, it is pulled back by the amount equivalent to the clearance inside the conduit tube. The length corresponding to this clearance is the welding torch posture (conduit tube posture) by the robot, the degree of wear on the inner wall of the conduit tube, and the contact tip. Degree of wear,
The accuracy of the predetermined length L management is low in the unique control such as the timer control because it is largely influenced by the variable control and is not constant.
An object of the present invention is to provide a wire protrusion amount adjusting method that can shorten the cycle time of welding and movement, is not affected by poor conduction, and can perform highly accurate adjustment.

[0004]

The method of the present invention for achieving the above object is as follows. (1) At the end of welding at one welding site, the wire feeding device stops feeding the wire to the welding torch, and then the wire is clamped by a clamping device located on the welding torch side of the wire feeding device. Then, the wire feeding device is driven in a direction opposite to the direction in which the wire is fed to remove a surplus portion of the wire between the wire feeding device and the clamping device, and then by the clamping device. Welding, characterized in that a series of wire protrusion amount adjusting steps for releasing the clamp of the wire is performed by temporally overlapping with the movement of the welding torch by the robot from the one welding portion to the next welding portion. Wire protrusion amount adjustment method. (2) The welding wire protrusion amount adjusting method according to (1), wherein the wire is clamped by the clamp device at or near the site of the welding torch. (3) When a torque of a predetermined value or more is applied when removing the excess wire, the wire feeding device causes slippage between the drive gear and the motor shaft, and the welding wire protrusion amount adjustment according to (1). Method.

In the welding wire protrusion amount adjusting method of the above (1), the movement of the welding torch from one welding portion to the next welding portion by the robot and the welding wire protrusion amount adjusting step are performed in a timely overlapping manner. Therefore, the welding wire protrusion amount adjustment is performed within the movement time, and the welding wire protrusion amount adjustment time and
The cycle time of welding and transfer is shortened. Above (2)
In the welding wire protrusion amount adjustment method of (1), since the wire is clamped at or near the welding torch site, the wire protrusion amount is maintained at the protrusion amount determined by the burn-up amount at the end of welding. Welding can start. Therefore, it is not necessary to use the touch sensor method for adjusting the wire protrusion amount, and problems such as poor conduction and wire bending when using the touch sensor method do not occur. In the welding wire protrusion amount adjusting method of the above (3), since the reverse feeding of the wire feeding device is provided with the torque limit action, the backward feeding of the wire feeding device is performed for a slightly longer time to remove the excess wire length with the predetermined torque. After that, it will be possible to slip automatically to remove the excess, and if the time is short, the excess may not be removed as in the case of timer control, or if the time is long, the excess pull-back force after removing the excess There is no problem that you may call. Further, since slippage occurs between the motor shaft and the drive gear and does not occur between the roller and the wire, abnormal wear of the wire and the resulting change in the clearance between the conduit tube and the wire are also prevented.

[0006]

1 to 9 show an apparatus for carrying out the method of an embodiment of the present invention and its operating process. Figure 1,
In FIG. 2, a welding robot (hereinafter referred to as a robot)
Welding wire (hereinafter referred to as wire) 3 on the arm 1
A wire feeding device 2 capable of forward and backward feeding is attached. The wire 3 is pulled out from the wire pail can 4, sent by the wire feeding device 2 (forward feed), and fed to the welding torch 6 via the conduit cable 5. The welding torch 6 is moved by the robot 1. A clamp device 8 capable of clamping and unclamping the wire 3 is provided on the welding torch 6 side of the wire feeding device 2, and the clamp device 8 is preferably provided at or near the welding torch 6. In the illustrated example, the clamp device 8 is provided between the conduit cable 5 and the welding torch 6.

As shown in FIG. 1, the robot 1 is controlled by a robot controller 17. The wire feeding device 2 is controlled by the welding power source 19. The welding power source 19 is controlled by the robot controller 17 via the interface unit 18. The robot controller 17 is controlled by the jig control device 16 via the interface unit 18. The clamp device 8 is controlled by the robot controller 17 via the interface unit 18. The welding gas opening / closing valve 22 is controlled by the robot controller 17 via the interface unit 18. The electrode terminal of the welding power source 19 is the work gripping device 2
0 and the welding torch 6 are connected to form a welding circuit between the workpiece 21 held by the workpiece holding device 20.

The wire feeding device 2 is, as shown in FIG.
It has a torque limiter 7. The torque limiter 7 is shown in FIG.
At the time of forward feeding of the wire in the clockwise direction, the rotation of the motor output shaft 9 is transmitted to the drive gear 10 and transmitted to the driven gear 12 via the transmission gear 11. The drive gear 10 and the driven gear 12 are composed of a gear portion and a roller portion. The roller portion holds the wire 3 between the rollers 13 and 14, and the drive gear 10 and the driven gear 12 are driven by frictional resistance. The wire 3 is fed by the rotational force of the gear 10 and the driven gear 12.

The torque limiter 7 has a mechanism for preventing the drive gear 10 from rotating due to slippage at a predetermined torque or more even when the motor output shaft 9 rotates counterclockwise when the wire is fed backward in the counterclockwise direction in FIG. Drive gear 10, transmission gear 11, driven gear 1
Do not rotate any of the two gears. As shown in FIG. 3, the torque limiter 7 has a pawl 7a, a ratchet 7b, and a spring 7c for pressing the pawl 7a against the ratchet 7b. The ratchet 7b rotates integrally with the motor shaft 9, and the pawl 7a moves around the motor shaft core. It rotates integrally with the drive gear 10. When the motor shaft 9 rotates to the right in FIG. 3 (forward wire feeding), the ratchet 7b is caught by the pawl 7a, and the rotation of the motor shaft 9 is transmitted to the drive gear 10 via the pawl 7a and the ratchet 7b. When rotating to the left in FIG. 3 (wire reverse feeding), the ratchet 7b pushes the pawl 7a against the bias of the spring 7c at a predetermined torque or more, the ratchet 7b and the pawl 7a slide, and the motor shaft 9 and the ratchet 7b move. Even if it rotates, the claw 7a and the drive gear 10 do not rotate. That is, in the wire reverse feeding, the rotation of the motor shaft 9 is transmitted to the drive gear 10 when the torque is smaller than the predetermined torque, but the rotation of the motor shaft 9 is not transmitted to the drive gear 10 when the torque is equal to or larger than the predetermined torque. This prevents the wire 3 from being unnecessarily worn between the roller portion of the drive gear 10 and the pressing roller 13 and between the roller portion of the driven gear 12 and the pressing roller 14 during reverse feeding.

4 to 6 show details of the clamp device 8. The clamp device 8 includes an air cylinder 14, a clamp claw 15, and an air valve 16. The clamp claw 15 is opened and closed by the air cylinder 14 controlled by the air valve 16. When the air valve 16 is OFF, the clamp claw 15 is in the open state (state of FIG. 5) and does not hinder the movement of the wire 3. Further, when the air valve 16 is ON, the clamp claw 15 is in the closed state (state of FIG. 6) and serves to hold and restrain the wire 3.

A method of adjusting the protruding amount of the welding wire according to the embodiment of the present invention which is carried out in the above apparatus will be described with reference to the time chart of FIG. At the time of welding at one welding site (a in FIG. 7), the wire feeding device 2 rotates in the normal direction and the wire 3
Is normally fed, and the clamp device 8 is in an open state so that the feeding of the wire 3 is not hindered. In FIG. 7, "B" indicates the time when the welding of one welding portion is completed. At the end of this welding, the wire feeding device 2 is stopped and the feeding of the wire 3 to the welding torch 6 is stopped. Then, as shown in FIG. 7C, the wire 3 is clamped by the clamp device 8 located on the welding torch 6 side of the wire feeding device 2 relative to the wire feeding device 2. Then, in Figure 7D,
The wire feeding device 2 reverses to feed the wire 3 backward, and the excess of the wire portion between the wire feeding device 2 and the clamp device 8 (excess length of the wire portion inside the conduit tube 5) is removed. Remove (remove slack) to optimize wire length. Then, in E of FIG. 7, the reverse rotation of the wire feeding device 2 is stopped, and the reverse feeding of the wire 3 is stopped. Then, Fig. 7
Then, the clamp of the wire by the clamp device 8 is released, and the wire 3 is opened.

The robot 1 performs this series of wire protrusion amount adjusting steps (a series of operations from B to F) between the welding end point at one welding site and the welding start point at the next welding site.
The welding torch 6 is moved with the movement of the welding torch 6.

In the above method, the clamping of the wire 3 by the clamping device 8 is performed at or near the site of the welding torch 6. Further, if a torque of a predetermined value or more is applied when removing the surplus portion of the wire 3, the wire feeding device 2
The torque limiter 7 causes slippage between the drive gear 10 and the motor shaft 9.

The operation of the above method will be described. As shown in the time chart of the present invention column of FIG. 8, the movement of the welding torch 6 from one welding portion to the next welding portion and the wire protrusion amount adjustment are performed redundantly, and the protrusion amount of the wire 3 is adjusted. This is performed while the welding torch 6 is being moved by the robot 1. Therefore, as can be seen from a comparison between the conventional column of FIG. 8 and the present invention column of FIG. 8, the wire protrusion amount adjustment time, which was conventionally performed by stopping the robot, is eliminated, and the welding and movement cycle time is shortened accordingly. To be done. Also in the movement, conventionally, the welding torch was moved from the welding portion to the protrusion amount adjusting station, and after adjusting the protrusion amount there, the welding torch was moved from the protrusion amount adjusting station to the next welding portion. In the method of the present invention, the welding torch 6 can be moved directly from one welding portion to the next welding portion, so that the movement time itself can be shortened as compared with the conventional case.

Further, since the wire 3 is clamped at the welding torch 6 portion or in the vicinity thereof, the wire protrusion amount L is maintained as the protrusion amount determined by the burn-up amount at the end of welding. The distance d between the burn-up amount at the welding site is set between the tip of the wire and the work, and the arc can be blown to the distance to start the next welding (see FIG. 9). Therefore, it is not necessary to use the touch sensor method as shown in FIG. 12 for adjusting the wire protrusion amount, and there is poor conduction in the case of the touch sensor method and wire bending (see FIG. 11 and FIG. 12).
03) etc. will not occur.

Further, since the reverse feeding of the wire feeding device 2 is provided with a torque limit action, the reverse feeding is performed for a slightly longer time to obtain an excess of the wire length with a predetermined torque, and then slip after that. Automatic surplus removal is possible, as in the case of timer control, it may not be possible to remove the surplus when the time is short, and when the time is long, excess pullback force may be applied after removing the surplus. There is no problem. That is, the wire length surplus removal time is automatically selected as the optimum time, and it is possible to remove the excess wire length surplus.

In addition, slippage is caused by the motor shaft 9 and the drive gear 1.
0 and not between the roller (the roller portion of the drive gear 10) and the wire 3, abnormal wear of the wire 3 and the resulting clearance change between the conduit tube 5 and the wire 3 are also prevented. .

[0018]

According to the method of the present invention, since the series of wire protrusion amount adjusting steps and the movement of the welding torch by the robot are temporally overlapped, the welding and movement cycle time can be shortened and the productivity is improved. Can be made. In the method of claim 2, since the wire is clamped at or near the welding torch site and the slack on the wire feeder side (in the conduit tube) is removed from the clamp site, once the wire is adjusted, the wire is clamped at the tip from the clamp site. The protrusion amount is hardly changed due to the slack, and highly accurate wire protrusion amount adjustment is guaranteed. According to the method of claim 3, since the torque limit function works in the wire reverse feeding, the reverse feeding torque and the backward feeding time can be automatically optimized, and the optimum wire surplus removal operation can be performed.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of an apparatus for carrying out the method of an embodiment of the present invention.

FIG. 2 is a schematic side view of an apparatus for carrying out the method of an embodiment of the present invention.

FIG. 3 is a side view of the wire feeding device of FIG.

FIG. 4 is a cross-sectional view of the welding torch and the clamp device of FIG.

FIG. 5: Clamp device is open (clamp is released)
5 is a cross-sectional view taken along the line AA of FIG. 4 in the case of FIG.

FIG. 6 is a view when the clamp device is in a clamped state.
FIG. 4 is a sectional view taken along line AA of FIG.

FIG. 7 is a time chart showing the relationship of operations of the robot, the wire feeding device, and the clamping device in the method of the embodiment of the present invention.

FIG. 8 is a time chart showing the relationship between each step of welding, movement, and wire protrusion amount adjustment between the method of the embodiment of the present invention and the conventional method.

FIG. 9 is a process drawing of performing welding in the method of the embodiment of the present invention.

FIG. 10 is a side view of the torch tip portion when an insulating compound is generated at the wire tip in the conventional method.

FIG. 11 is a side view of the torch tip when the wire is bent in the conventional method.

FIG. 12 is a process diagram for performing welding when the wire is bent in the conventional method.

[Explanation of Codes] 1 Robot 2 Wire feeder 3 Wire 6 Welding torch 7 Torque limiter 8 Clamping device 9 Motor output shaft

Claims (3)

[Claims] 1. At the end of welding at one welding site, the feeding of the wire by the wire feeding device to the welding torch is stopped, and then the wire is fed by a clamp device located on the welding torch side of the wire feeding device. And then driving the wire feeding device in the direction opposite to that of the wire feeding to remove the excess portion of the wire between the wire feeding device and the clamping device, and then the clamp A series of wire protrusion amount adjusting steps for releasing the clamp of the wire by the device is performed by temporally overlapping with the movement of the welding torch by the robot from the one welding portion to the next welding portion. Welding wire protrusion amount adjustment method. 2. The welding wire protrusion amount adjusting method according to claim 1, wherein the clamping of the wire by the clamping device is performed at a position of the welding torch or in the vicinity thereof. 3. The welding wire protrusion according to claim 1, wherein when a torque of a predetermined value or more is applied when removing the excess wire, the wire feeding device causes slippage between the drive gear and the motor shaft. Quantity adjustment method.