JPH11300474A - Combined spot welding gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the number of robots to be installed and the change frequency of the gun. SOLUTION: This is the spot welding gun 11 to be driven by a robot arm, and is equipped with at least two sets of welding electrodes 14A, 14B.... This is the combined spot welding gun 11 whose electrode on the one side of one set of the welding electrode and an electrode on the one side of another set of the welding electrode, are driven by the same actuator 13. The electrode on the one side of the one set of the welding electrode and the electrode on the one side of another set of the welding electrode, are moved in the opposite direction each other. The type or size of the welding electrode of each set, are different.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined spot welding gun having a plurality of sets of welding electrodes.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 4-253576 discloses a conventional welding robot having a single welding gun. In spot welding of a vehicle body assembly line, for example, in spot welding of a roof (roof panel) and reinforcement (aggregate), the welding points at the right and left ends of the roof are limited to one welding robot due to the access of the welding robot. Spot welding is performed with the welding gun held by the welding gun, and the welding points at the front and rear ends of the roof are spot-welded by the welding gun held by another welding robot. Therefore, spot welding between the roof and the reinforcement normally requires a plurality of welding robots, and a large space is required for disposing the welding robots.

[0003]

However, in order to reduce the installation area of a welding robot in an assembly line of a vehicle body, if one welding robot is to be provided with a plurality of welding guns, the welding gun must be replaced. Welding gun change) is required, and the tact time becomes longer. The purpose of the present invention is
An object of the present invention is to provide a combined spot welding gun that can reduce the number of welding robots to be installed and the number of welding gun changes.

[0004]

The present invention to achieve the above object is as follows. (1) A spot welding gun driven by a robot arm, comprising at least two sets of welding electrodes, wherein one electrode of one set of welding electrodes and one electrode of another set of welding electrodes are connected. A compound spot welding gun driven by the same actuator. (2) The driving direction of the actuator for causing the one set of welding electrodes to act in the closing direction and the driving direction of the actuator for causing the other set of welding electrodes to act in the closing direction are opposite to each other. (1) The composite spot welding gun according to (1), wherein: (3) The combined spot welding gun according to (1) or (2), wherein the types or sizes of the welding electrodes of each set are different.

In the combined spot welding guns (1) and (3), since two sets of welding electrodes are driven by one actuator, a plurality of welding guns can be used while suppressing an increase in the weight and size of the welding gun. It becomes possible to have. Therefore, the number of robots to be installed is reduced and the number of welding gun changes is reduced as compared with the related art in which one robot supports only one type of welding gun. If there is a welding gun change, it is necessary to calibrate the reference of the control system, which takes time, and the production tact time becomes long. However, the present invention can suppress it. In the combined spot welding gun of the above (2), when one welding electrode is operated in the closing direction, the other welding electrode is not closed, so that unnecessary wear of the electrodes can be prevented.

[0006]

1 to 4 show a composite spot welding gun according to a first embodiment of the present invention, and FIG. 5 shows a second embodiment of the present invention.
FIG. 6 shows a composite spot welding gun according to an embodiment, and FIG. 6 shows a case where the composite spot welding gun according to the first embodiment is applied to spot welding of a roof and a reinforcement of an automobile. Components common to the first and second embodiments of the present invention are denoted by the same reference numerals in both embodiments.

First, portions common to the first and second embodiments of the present invention will be described with reference to FIGS. 1 to 4 and 5, for example. The combined spot welding gun according to the embodiment of the present invention is a spot welding gun 11 driven by an arm of a robot (for example, a six-axis robot) 12, as shown in FIGS. The welding gun 11 includes at least two sets of welding electrodes 14A, 14B,. One electrode 14Aa of one set of welding electrodes 14A and one electrode 14Ba of the other set of welding electrodes 14B are the same actuator 13 (rotary type actuator, for example, an AC (AC) servomotor, a DD (direct drive). ) Consisting of a motor, an air actuator, etc.).

At least two sets of welding electrodes 14A, 14
B,... Are different from each other in form or size. Therefore, different welding electrodes 14A, 14B,.
.. Constitute a compound spot welding gun driven by a single common actuator 13. Here, different welding electrodes 14A, 14B,... Are provided with a new type of welding electrode 14A proposed by the present applicant in Japanese Patent Application No. 8-285421 and a conventional X-type welding gun. A welding electrode selected from the electrode 14B, the welding electrode 14C of a conventional C-type welding gun, and the like are included.

The actuator 13 has a shaft core 15,
Stator 1 having axis 15 common to actuator axis
6 and a rotor 17 rotatable around a shaft center 15 with respect to a stator 16. The stator 16 supports the stator-side welding electrodes 14Ab and 14Bb, and the rotor 17 supports the rotor-side welding electrodes 14Aa and 14Ba.

[0010] The stator 16 has an extending portion 1 extending axially forward.
9 and an arm 20 extending on the circumference centered on the axis 15 at the distal end of the extension 19. Similarly, rotor 1
7 has an extending portion 21 extending forward in the axial direction;
Has an arm 22 extending on the circumference centered on the axis 15. The arm 20 and the arm 22 extend on the same circumference around the axis 15 of the actuator 13. The length l ₁ of the extending portions 19 and 21 may be freely increased as long as the strength and rigidity are allowed. Also, arm 2
The radius r ₁ of 0 and 22 may be set to an appropriate value.

The robot 12 is, for example, a six-axis robot (for example, a six-joint robot). Stator 16
As shown in FIG. 1, is mounted on the wrist of the robot 12 such that the axis of the rotation axis, which is the sixth axis of the robot, and the axis 15 of the actuator coincide with each other. Therefore,
The stator 16 of the actuator is rotatable around its own axis 15 by the robot 12. Since the rotor 17 is rotatable with respect to the stator 16, both the rotor 17 and the stator 16 are rotatable around the axis 15. Therefore, the welding electrodes 14Aa and 14Ba on the rotor side and the welding electrodes 14Ab and 14Bb on the stator side can relatively approach and separate in the rotation and anti-rotation directions.

The rotation angle of the rotor 17 is controllable,
An output signal of an encoder (not shown) provided in the actuator 13 is sent to the robot controller, and an output signal of the
By controlling the servo motor of the above. In addition, the rotation angle of the stator 16 around the axis can be controlled, and the robot controller controls the sixth angle of the robot.
This can be performed by controlling the rotation angle of the shaft.

By making the rotation angles of the rotor 17 and the stator 16 adjustable, it is possible to selectively open and close the welding electrode. For example, the rotor 17 can be provided with an equalizing function so as to be able to cope with a change in the contact position of the welding electrode 14, thereby making it possible to eliminate the equalization (there is no need to provide an equalizer). . Further, the stator 16 is stopped at a position in contact with the workpiece, and the rotor 17 is driven to open and close the clamp (corresponding to the conventional C-type welding gun clamp opening and closing). The clamp 16 can be opened and closed by driving the stator 16 and the rotor 17 by substantially the same amount from both sides with respect to the work to be welded (corresponding to the conventional X-type welding gun clamp opening and closing). By selecting these clamp opening / closing patterns according to the shape of the workpiece, it is possible to perform appropriate welding in accordance with the welded portion of the workpiece.

FIGS. 2 and 3 also show the detailed structure of the drive unit of the welding gun. The rotary type actuator 13 of the welding gun 11 may be an air-driven type or an electric-driven type. Since both are commercially available, they can be used. In the case of an electric actuator, there is an assembly of an AC servomotor and a speed reducer, a direct drive (DD) type servomotor, or the like, and any of them may be used. Since the DD type servo motor does not need to use a gear and a speed reducer, it is excellent in that disturbance to the control system due to wear is reduced, and overhaul and maintenance are reduced. The illustrated example shows a case of a DD type servo motor. 2 and 3, a rotor 17 is rotatably supported by a stator 16 at a central portion, and the rotor 17 is rotationally driven by energizing a coil portion 18.

The structure for conducting the welding current is as follows.
The workpiece is clamped between the stator-side welding electrode 14 and the rotor-side welding electrode 14, and a welding current is applied between the chips to weld the workpiece. In that case, the welding current from the external power supply is sent to the transformer 24 via the connector 27, and the path 25,
Electric current is supplied to the welding electrode 14 on the stator side and the welding electrode 14 on the rotor side via 26. The stator 16 includes a bracket 28, and the transformer 24 is supported by the bracket 28, and the robot 12 is supported by the bracket 28.

A terminal 23 that is turned on and off by a relative rotation of the rotor 17 with respect to the stator 16 is provided in a path for supplying a welding current to the welding tip 14. The terminal 23 is pressed and turned on when the rotor-side welding electrode 14 and the stator-side welding electrode 14 approach each other up to an angle at which the work piece is clamped, and is off when they are at an angle apart from each other. The on / off angle is set in advance so that Therefore, the terminal is constituted by a terminal of a type in which a welding current flows between the welding tip 14 on the rotor side and the welding electrode 14 on the stator side only at the time of clamping, and otherwise cuts off the current.

Next, a plurality of types of welding electrodes that can be attached to the welding gun (welding electrode 14A of a new type of welding gun proposed in Japanese Patent Application No. 8-285421, welding electrodes 14B and C of an X-type welding gun). Electrode 14 for die welding gun
C) will be described. The welding electrode of the welding gun is Japanese Patent Application No. 8-28.
Welding electrode 1 for new type of welding gun proposed in 5421
The structure near the welding electrode in the case of 4A is as follows. Figure 2, as shown in FIG. 3, the radius r ₁ of the arms 20 and 22 is smaller than the radius of the motor part of the actuator 13, the length l ₁ of the extending portion 19, 21 other types of welding electrodes 14B , 14C. The welding electrode 14Ab on the stator side is attached to the tip of the arm 20 on the stator 16 side, and the welding electrode 14Aa on the rotor side is attached to the tip of the arm 22 on the rotor 17 side.
Stator-side welding electrode 14Ab and rotor-side welding electrode 14
Aa is on the same circumference centered on the axis 15 of the actuator 13 and is relatively approachable / separable.

The welding electrode is a welding electrode 14 of an X-type welding gun.
In the case of B, the structure near the welding electrode is as follows. As shown in FIGS. 2 and 3, the radius r ₂ of the arms 20 and 22 is larger than the radius of the motor section of the actuator 13, and the arms 20 and 22 are tangential to the actuator motor section from the tips of the extending sections 19 and 21. The actuator 13 is bent substantially linearly at its tip and extends in an arc shape centered on the axis 15 of the actuator 13. The length l ₂ of the extending portion 19, 21 is shorter than that of the welding electrode 14A of the new type of welding gun proposed in Japanese Patent Application No. Hei 8-285421. The tip of the arm 20 on the stator 16 side has a welding electrode 1 on the stator side.
4Bb is attached to the arm 2 on the rotor 17 side.
A welding electrode 14Ba on the rotor side is attached to the front end of 2. The stator-side welding electrode 14Bb and the rotor-side welding electrode 14Ba are on the same circumference centered on the shaft core 15 of the actuator 13, and are relatively close to / separable from each other.

The welding electrode is a welding electrode 14 of a C-type welding gun.
In the case of C, the structure near the welding electrode is as follows. As shown in FIG. 5, the rotor-side arm 22 is rotatably connected to the tip of the rotor-side extension 21 of the actuator 13 and is a first arm 22 that extends perpendicular to the extension 21.
a and a second arm 22b rotatably connected to the tip of the first arm 22a and extending substantially perpendicular to the first arm 22a. A rotor-side welding electrode 14Ca is attached to the tip of the second arm 22b. Second arm 22b
The end opposite to the end on which the welding electrode 14Ca is attached is connected to the case member 30 on the welding transformer 24 side.
The roller 32 is movably supported between two rows of rollers 32 supported by a bracket 31 extending from the bracket 31 and is capable of reciprocating in a pressing direction. Rotor side welding electrode 14Ca
A welding electrode 14Cb on the stator side is arranged at a position facing the above. The stator-side welding electrode 14Cb is attached to the tip of an arm extending from the stator-side extension of the actuator 13, or, as shown in FIG. 5, a bracket extending from the case member 30 on the welding transformer 24 side. It is attached to the tip of an arm 34 that is attached to the tip of 33 and extends substantially perpendicular to the bracket 33. As the rotor of the actuator 13 rotates, the welding electrode 14Ca on the rotor side relatively approaches or separates from the welding electrode 14Cb on the stator side, and when approaching, presses the work to perform spot welding.

Next, parts unique to each embodiment of the present invention will be described. In the first embodiment of the present invention, a single welding gun 1
First, a welding electrode 14B of an X-type welding gun and Japanese Patent Application No. 8-28
Welding electrode 1 for new type of welding gun proposed in 5421
4A, thereby providing a composite spot welding gun in which a plurality of types of welding electrodes are provided in one welding gun. In this case, the arm to which the welding electrode 14B is attached and the arm to which the welding electrode 14A is attached extend in the opposite directions from the distal end of the extending portion 21, and when the one welding electrode 14A moves in the closing direction, the other electrode 14B Move in the open direction. Thus, when one electrode is pressurized, the other electrode is open, so that the electrodes are not worn and the durability of the welding gun 11 is improved.

FIG. 6 shows a case where the composite welding gun 11 is used to spot weld a roof panel 40 of an automobile to a reinforcement. In this case, welding spots 4 at the left and right end portions of the vehicle, which are arranged in the vehicle longitudinal direction.
1 is spot-welded by the X-type welding electrode 14B. The wrist axis of the robot 12 is reversed between when spot welding the welding point at the left end of the vehicle and when spot welding the welding point at the right end of the vehicle. Welding points 42 arranged in the left-right direction of the vehicle at the front-rear end of the vehicle
Is welded by the welding electrode 14A of a new type of welding gun proposed in Japanese Patent Application No. 8-285421. This is X
If the robot is to be welded with the mold welding electrode 14B, the posture of the robot will be unreasonable, and the robot position must be largely separated from the welding position. Therefore, if the part is to be welded, a large robot must be used. In addition, the size of the welding line including the position where the robot is arranged has to be increased. However, the use of the embodiment of the present invention can prevent the robot and the welding line from increasing in size.

As shown in FIGS. 2 to 4, the welding gun 11 of the first embodiment of the present invention has a stator-side conductive clamper 51 attached to the stator-side extension 19, A rotor-side conductive clamper 52 is attached to the rotor-side extension 21. The rotor is rotated to bring the rotor-side clamper 52 closer to the stator-side clamper 51, and the end of the arc torch 53 is held between the rotor-side clamper 52 and the stator-side clamper 51. By
Using this arc torch 53, arc welding can also be performed. When performing arc welding, spot welding is not performed.

In the second embodiment of the present invention, a single welding gun 11 is provided with two sets of welding electrodes 14C of a C-type welding gun having different sizes or shapes, thereby providing a plurality of types of welding electrodes. This is a combined spot welding gun in which the welding electrodes are provided in one welding gun. in this case,
One set of welding electrodes 14C is attached to one end of the arm, and the other set of welding electrodes 14C is attached to the other end of the arm. When one welding electrode 14C moves in the closing direction, the other electrode is used. 14C moves in the opening direction. Thus, when one electrode is pressurized, the other electrode is open, so that the electrodes are not worn and the durability of the welding gun 11 is improved.

In the above description, one welding gun 11 is provided with
In the case where the welding electrode 14A of the new type welding gun and the welding electrode 14B of the X-type welding gun proposed in -285421 are attached (first embodiment), two sets of C-type welding guns are mounted on one welding gun 11. When the welding electrode 14C is attached (second
Example) and the above, but the combination of the welding electrodes attached to one welding gun is not limited to this. For example, the welding electrode 14A of a new type of welding gun proposed in Japanese Patent Application No. 8-285421 is used. Welding electrode 14 for C-type welding gun
C may be attached to one welding gun, and welding electrode 14B of X-type welding gun and welding electrode 1 of C-type welding gun
4C may be attached to one welding gun.

[0025]

According to the first aspect of the present invention, since two sets of welding electrodes are driven by one actuator, a plurality of welding guns can be provided while suppressing an increase in the weight and size of the welding gun. It is possible to make it. Therefore, the number of installed robots is reduced as compared to the conventional case where only one type of welding gun is supported by one robot,
In addition, the number of welding gun changes is reduced. According to the combined spot welding gun of the second aspect, when one welding electrode is operated in the closing direction, the other welding electrode is not closed, so that unnecessary wear of the electrodes can be prevented. According to the composite spot welding gun of the third aspect, since two sets of welding electrodes are driven by one actuator, it is possible to have a plurality of welding guns while suppressing an increase in the weight and size of the welding gun. Become.

[Brief description of the drawings]

FIG. 1 is a perspective view of a composite spot welding gun according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the combined spot welding gun according to the first embodiment of the present invention.

FIG. 3 is a side view of the combined spot welding gun according to the first embodiment of the present invention.

FIG. 4 is a front view of the combined spot welding gun according to the first embodiment of the present invention.

FIG. 5 is a perspective view of a combined spot welding gun according to a second embodiment of the present invention.

FIG. 6 is a plan view of an automobile assembly welding line using the composite spot welding gun according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Welding gun 12 Robot 13 Actuator (for example, motor) 14 Welding electrode 15 Axis of (actuator) 16 Stator 17 Rotor 18 Coil 19 Extension 20 Arm 21 Extension 22 arm 22a First arm 22b Second arm 23 Terminal 24 Transformer 25, 26 (Welding current) path 27 Connector 28 Bracket 30 Case member 32 Roller 33 Bracket 34 Arm 41, 42 Welding point 51, 52 Clamper 53 Arc torch

Claims (3)

[Claims] 1. A spot welding gun driven by a robot arm, comprising at least two sets of welding electrodes, one electrode of one set of welding electrodes and one electrode of another set of welding electrodes. Are driven by the same actuator. 2. A driving direction of the actuator for causing the one set of welding electrodes to act in the closing direction and a driving direction of the actuator for causing the other set of welding electrodes to act in the closing direction are opposite to each other. The composite spot welding gun according to claim 1, wherein the gun is set so as to be oriented in the direction. 3. The combined spot welding gun according to claim 1, wherein the types or sizes of the welding electrodes in each set are different.