JP3537014B2 - Spot welding gun - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a spot welding gun used for assembling an automobile body, for example, has a compact structure, and has little interference with a panel to be welded, a jig, and peripheral equipment. In addition, the present invention relates to a spot welding gun capable of vertically pressing an electrode tip against a panel to be welded.

[0002]

2. Description of the Related Art Welding guns used for spot welding, which is a kind of resistance welding, are roughly classified into C-type guns and X-type guns.

FIG. 2 shows an example of a C-type welding gun, and shows a C-type spot welding gun 10 shown in FIG.
Reference numeral 0 denotes, for example, a gun arm 103 having a hook-shaped extension extending downward from the gun bracket 101 connected to the arm A of the welding robot and having an electrode tip 102 exchangeably mounted at the tip thereof, and a gun bracket 101 in the figure. Servo motor 106 which is mainly constituted by a ball screw 105 which is supported so as to be movable in the vertical direction, and which has an electrode tip 104 exchangeably mounted at the lower end in the figure, is provided on gun bracket 101.
The electrode tip 104 is moved together with the ball screw 105 by the rotation of the ball nut 108 transmitted from the apparatus via the timing belt 107, and energization and pressurization are performed in a state in which a workpiece (not shown) is sandwiched between the electrode tip 102 and the electrode tip 102. As a result, the material to be welded is welded.

FIG. 3 shows an example of an X-type welding gun, and the X-type spot welding gun 110 shown in FIG.
Is a hook-shaped fixed gun arm 112 which extends substantially horizontally from a gun bracket 111 also connected to the arm A of the welding robot, a base end side of which is rotatably supported by the gun bracket 111 and has a speed reducer. Servo motor 113
A movable gun arm 114, which is also hook-shaped, which opens and closes with respect to the fixed gun arm 112 by the drive of the armature, and has a structure in which electrode tips 115 and 116 are interchangeably attached to the tips of the fixed and movable gun arms 112 and 114, respectively. The workpiece to be welded (not shown) is sandwiched between the electrode tips 115 and 116 by the rotation of the movable gun arm 112 based on the operation of the servomotor 113, and current is applied and pressurized in this state to weld the workpiece. It has become.

[0005]

However, in the above-described conventional C-shaped spot welding gun 100, the portion near the upper end of the ball screw 105 becomes an indispensable space for the mechanism of the welding gun 100, so that this portion is required. There is a problem that the position and movement of the welding gun 100 are restricted in order to avoid interference with a panel to be welded, a welding jig, and other peripheral equipment.

On the other hand, in the X-type spot welding gun 110 shown in FIG. 3, since the movement of the movable gun arm 114 is a rotational movement about the support shaft, the movement trajectory of the electrode tip 116 becomes circular. In addition to the problem that the electrode tip 116 cannot be brought into vertical contact with the panel to be welded, if the length of the gun arms 112 and 114 changes, the pressing force on the panel to be welded also changes. There is a problem that it is necessary to replace the torque with a torque corresponding to the length, and solving such problems is a problem in operation or quality of the conventional C-type and X-type spot welding guns. Had become.

In FIGS. 2 and 3, a servo gun using a servo motor as an actuator has been described, but the basic structure of an air gun using an air cylinder is not changed. It has.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in conventional C-type and X-type spot welding guns, and is compact and has little interference with a panel to be welded or a jig. Moreover, it is an object of the present invention to provide a spot welding gun which can press the electrode tip vertically against the panel to be welded and which does not change the pressing force even if the length of the gun arm changes.

[0009]

A spot welding gun according to a first aspect of the present invention is a spot welding gun attached to an arm of a welding robot, comprising: a first gun arm extending from a gun body; A pressure drive mechanism disposed on the first gun arm extension base end side; and a pressure drive mechanism disposed opposite to the first gun arm, and slid along the gun body based on the operation of the pressure drive mechanism; A second gun arm that approaches and separates from the first gun arm, wherein the pressure drive mechanism includes a ball screw, a sliding nut screwed into the ball screw, and a guide unit including a linear guide for guiding the sliding nut; The second gun arm includes an electric motor that rotationally drives the ball screw, and the second gun arm is configured to be in a closed state with the electrodes attached to the first and second gun arms. A mounting base that is offset toward the first gun arm by an amount sufficient to prevent the guide unit from extending from the second gun arm in a direction in which the second gun arm is separated from the gun arm, and the sliding nut at the base end; The spot welding gun is a means for solving the above-mentioned conventional problems.

[0010] As an embodiment of the spot welding gun according to the present invention, the welding gun according to claim 2 is characterized in that the electric motor is a servomotor.

Further, as a preferred embodiment of the spot welding gun according to the present invention, in the welding gun according to the third aspect, the first gun arm, the second gun arm, and the pressurizing drive mechanism are provided so as to be exchangeable. In addition, such a configuration of the spot welding gun is characterized as a means for solving the above-mentioned conventional problems.

[0012]

According to the first aspect of the present invention, there is provided a spot welding gun comprising: a first gun arm extending from a gun body;
It mainly comprises a second gun arm disposed opposite to the gun arm, and a pressure drive mechanism for sliding the second gun arm along the gun body, and the pressure drive mechanism is laid out on the base end side of the gun arm in the gun body. In comparison with conventional C-type guns, there are no protruding parts that are indispensable in the mechanism, so interference with the panel to be welded or jigs is reduced, and the welding position and the movement of the welding gun are restricted. Reduced
Compared to the conventional X-type gun, the second gun arm moves in parallel, so that the electrode tip can always abut against the panel to be welded vertically, and the electrode tip always remains constant even if the length of the gun arm changes. This brings about an extremely excellent effect that a pressing force can be applied. That is,
ADVANTAGE OF THE INVENTION According to this invention, while eliminating the disadvantage of each of the conventional C type and X type welding guns, the advantage which can utilize the advantage as it is and can improve the versatility of a spot welding gun is brought.

In the above-mentioned welding gun, the pressurizing drive mechanism comprises a guide unit comprising a ball screw, a sliding nut and a linear guide, and an electric motor for driving the ball screw to rotate. The guide unit is attached to the sliding nut at the attachment base end offset to the side, and the guide unit does not extend from the second gun arm in the direction away from the first gun arm when the electrodes attached to the first and second gun arms are closed. Offset enough to reduce the size of the pressure drive mechanism, reduce the dead space of the welding gun, and make the welding gun more compact. The effect is brought about.

In a spot welding gun according to a second aspect of the present invention, a servomotor having excellent instantaneous force and holding force is used as the electric motor, so that the operation of the gun arm can be performed smoothly. In addition, the spot welding gun according to the third aspect of the present invention has a structure in which the first gun arm, the second gun arm, and the pressure drive mechanism are replaceable. Therefore, it is possible to freely cope with variations of the gun arm according to the shape of the work to be welded, and an excellent effect that the versatility of the welding gun can be enhanced is brought about.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

FIGS. 1A and 1B are a front view and a side view showing the structure of a spot welding gun according to one embodiment of the present invention. The spot welding gun 1 shown in FIG. A gun body 2 attached to an arm A of the welding robot indicated by a virtual line therein, a first gun arm 3 extending horizontally from a lower end portion of the gun body 2 in the drawing, and provided inside the gun body 2. The pressure driving mechanism 4 is mounted on a sliding nut 6b, which will be described later, of the pressure driving mechanism 4 so as to face the first gun arm 3, and the gun body 2 is moved based on the operation of the pressure driving mechanism 4. It is mainly composed of a second gun arm 5 that moves vertically along the drawing.

Shanks 3a and 5a made of a copper-based alloy are attached to the distal ends of the first and second gun arms 3 and 5 so as to face each other.
The electrode tips 3b and 5b, which are also made of a copper-based alloy and have spherical tip portions, are removably attached (replaced according to wear) at the tip portions.

The pressure driving mechanism 4 includes a ball screw 6a and a sliding nut 6b screwed to the ball screw 6a.
And a guide unit 6 comprising a linear guide 6c for guiding the sliding nut 6b in the vertical direction in the figure, and a servo motor 7 for rotating the ball screw 6a of the guide unit 6 via a pulley 7a and a timing belt 7b. The base end of the second gun arm 5 is attached to the sliding nut 6b of the guide unit 6. Then, the rotation of the ball screw 6a based on the operation of the servo motor 7 is converted into a linear motion of the sliding nut 6b, and the second gun arm 5 is moved to the gun body 2 together with the sliding nut 6b within a range indicated by a virtual line in the figure. It moves up and down along.

At this time, the second gun arm 5 is
Since the base unit 5c is connected to the sliding nut 6b of the guide unit 6 on the lower side in the figure of the base end 5d bent in an L-shape from the arm body 5c to which the a and 5b are attached, the guide unit 6 is moved upward in the figure. The two gun arms 3 and 5 in the closed state of the electrodes without extending
Can be secured, and the entire structure of the welding gun 1 can be made compact.

In the spot welding gun 1 according to this embodiment, the first gun arm 3, the second gun arm 5, and the pressure drive mechanism 4 are structured so as to be detachable from the gun body 2, so that they can be connected to each other. It can be exchanged.

The spot welding gun 1 having such a structure is mounted on, for example, a welding robot and moves to a predetermined welding position according to a predetermined program. Then, the second gun arm 5 is moved toward the first gun arm 3 by the operation of the servo motor 7 of the pressure drive mechanism 4, and the welded panel (not shown) is moved to the two electrode tips 3b and 5.
b and both electrode tips 3b, 5b
The panel to be welded is joined by applying a current between them.

At this time, since the welding gun 1 is made compact and the interference part is reduced as compared with the conventional welding gun, there are few restrictions on the moving path and the welding position.
By selecting the shortest moving path and the optimal welding location, the efficiency of the welding process can be improved. Further, since the second gun arm 5 moves in parallel, the electrode tips 3b, 5b can be brought into contact with the panel to be welded at a right angle, and the electrode tips 3b, 5b are consumed, and the shape and dimensions of the gun arm are changed. Even if it does, the pressing force becomes constant.

Further, the spot welding gun 1 is provided with a plurality of interchangeable first and second gun arms and a pressure drive mechanism, so that the size of the gun arm can be adjusted according to the shape and characteristics of the workpiece. It is possible to freely combine the dimensions (the so-called edge dimensions), the arm shape, the pressing force and the moving speed of the gun arm, etc., thereby enabling a highly versatile application for desired specifications.

[Brief description of the drawings]

FIG. 1A is a front view showing the structure of a spot welding gun according to one embodiment of the present invention. (B) It is a side view of the spot welding gun shown in FIG. 1 (a).

FIG. 2 is a side view showing a structural example of a conventional C-type spot welding gun.

FIG. 3 is a side view showing a structural example of a conventional X-type spot welding gun.

[Explanation of symbols]

1 spot welding gun 2 Gun body 3 First gun arm 4 Pressure drive mechanism 5 Second gun arm 6 Guide unit 6a Ball screw 6b sliding nut 6c Linear guide 7 Servo motor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 11/11 520 B23K 11/11 550

Claims (3)

(57) [Claims] 1. A spot welding gun attached to an arm of a welding robot, comprising: a first gun arm extending from a gun body; and a pressure drive mechanism disposed on a base end side of the gun body extending from the first gun arm. A second gun arm disposed opposite to the first gun arm, sliding along the gun body based on the operation of the pressure driving mechanism, and approaching and separating from the first gun arm; The pressure drive mechanism includes a ball screw, a sliding nut screwed into the ball screw, a guide unit including a linear guide for guiding the sliding nut, and an electric motor that rotationally drives the ball screw. The second gun arm Are guide guides in the direction in which the second gun arm is separated from the first gun arm when the electrodes attached to the first and second gun arms are closed. A mounting base offset to the side of the first gun arm by an amount sufficient to prevent the slot from extending from the second gun arm, the base being mounted to the sliding nut at the base end. Spot welding gun. 2. The spot welding gun according to claim 1, wherein the electric motor is a servomotor. 3. The spot welding gun according to claim 1, wherein the first gun arm, the second gun arm, and the pressurizing drive mechanism are disposed interchangeably.