JP2001259854A - Spot welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spot welding equipment with which versatile applicability and simplification of the spot welding facility are attempted. SOLUTION: The spot welding equipment is provided with a welding robot 6 which supports a spot welding gun 8 and moves the spot welding gun 8 to the welding point of a work 1, and a robot 7 for moving an intermediate electrode, which supports the intermediate electrode 15 which is held and pressurized together with the work 1 by the spot welding work to prevent the generation of pressurized spots on the work 1, and moves the intermediate electrode 15 toward the welding point of the work 1. The spot welding gun 8 is moved toward the welding point and the intermediate electrode 15 is also moved toward the welding point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot welding apparatus and, more particularly, to a spot welding apparatus for preventing an indentation on a work due to spot welding by holding and pressing an intermediate electrode together with the work during spot welding.

[0002]

2. Description of the Related Art Conventionally, when spot welding is performed on an outer panel such as a front pillar outer around a door and a reinforcement member as a reinforcing member in a welding assembly process of an automobile body, for example, spot welding indentations are formed on the outer surface of the outer panel. In order to prevent occurrence of such a problem, a method has been performed in which an intermediate electrode is applied to a hit point, and the intermediate electrode is sandwiched together with an outer panel and a reinforcement to perform spot welding.

A plurality of intermediate electrodes are provided as a part of a jig for holding a work such as an outer panel so as to correspond to each spot position of spot welding, and the mounting position is set in accordance with the shape of the work at each spot position. ing.

However, since these intermediate electrodes are provided on a jig for holding a workpiece, the same number of intermediate electrodes as the number of spots for performing spot welding and a plurality of intermediate electrodes for holding these intermediate electrodes are provided. A bracket is required, and the work of maintaining all the intermediate electrodes at the holding positions and the maintenance work are complicated.

In view of the above, various methods have been conventionally proposed. For example, Japanese Patent Application Laid-Open No. 4-197585 discloses a spot welding gun having an integral intermediate electrode. FIG. 4 is a schematic view of the spot welding gun disclosed in the above publication.

According to the above publication, the spot welding gun 10
Reference numeral 1 denotes a cradle 10 of the spot welding gun 101 which is connected to and supported by the tip of a robot arm (not shown).
2, a pair of gun arms 103 is pivotally supported by hinge pins 104 so as to be openable and closable. An electrode tip 105 is mounted on a tip of the gun arm 103, and an intermediate electrode 108 is rotatably supported on a tip of the cradle 102. ing.

The gun arm 103 is connected to the actuator 10
The work is spot-welded by holding and pressing the intermediate electrode 108 together with the work between the electrode tips 105 by opening and closing by the operation of 7.

[0008]

However, according to JP-A-4-197585, since the intermediate electrode 108 is provided integrally with the spot welding gun 101, it is difficult to cope with works having various shapes. Therefore, a spot welding gun corresponding to the work is required, and there is no versatility, and the structure becomes complicated and the control becomes complicated.

[0009] In addition, due to the increase in the size of the spot welding gun,
The weight of the spot welding gun 101 increases, and a large robot is required to move the spot welding gun 101, which is not preferable.

[0010] The present invention has been made in view of the above points, and an object of the present invention is to provide a spot welding apparatus which simplifies the versatility and simplification of spot welding equipment.

[0011]

According to a first aspect of the present invention, there is provided a spot welding apparatus for supporting a spot welding gun for performing spot welding by nipping and pressing a work between tips of a pair of gun arms. And a welding robot for moving the spot welding gun to the hitting position, and supporting an intermediate electrode which is pinched and pressed together with the work by the spot welding gun to prevent generation of an indentation on the work, and moves the intermediate electrode to the hitting position. And a robot for moving the intermediate electrode.

According to the first aspect of the present invention, the spot welding gun and the intermediate electrode are held and moved by separate robots, respectively, so that the spot welding gun and the intermediate electrode can be easily adapted to works having various shapes. The versatility of the spot welding equipment can be provided without the need for a gun.

Further, the intermediate electrode is only required to be lightweight and to be able to be held at the hitting position with an accuracy sufficient to prevent generation of an indentation on the work due to spot welding, and the required accuracy is low. It is possible to use a robot having a simple configuration and easy control, and a relatively simple welding robot can be used without increasing the size of the spot welding gun. Thus, the spot welding equipment can be simplified.

A spot welding apparatus according to a second aspect of the present invention is characterized in that the intermediate electrode has a shape extending over a plurality of hit points. According to the second aspect of the present invention, since the intermediate electrode has a shape extending over a plurality of hit points, the spot welding gun is moved by the welding robot while the intermediate electrode is held by the intermediate electrode moving robot. With only this, it is possible to perform spot welding at a plurality of spot positions. Therefore, the robot control can be simplified and the spot welding at a plurality of locations can be performed in a shorter time, and the work efficiency can be improved.

According to a third aspect of the present invention, the intermediate electrode has a shape in which a contact surface that contacts the work has a shape corresponding to the work. According to the third aspect of the present invention, since the contact surface of the intermediate electrode has a shape corresponding to the work, the contact surface can be reliably brought into contact with the work, and the occurrence of indentations on the work due to spot welding can be more effectively prevented. Can be.

[0016]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view schematically showing the present embodiment, and FIG. 2 is an enlarged view of a main part when FIG.

Hereinafter, a sub-assembly for connecting the front pillar outer and the reinforcement will be described as an example.
In FIG. 1, reference numeral 1 denotes a work to be spot-welded, which is fixed by a plurality of clamps 4 provided on a jig (not shown) installed on the floor. Work 1
Is an outer panel of the vehicle in this embodiment, more specifically, a front pillar outer 2 around a door and a reinforcement 3 as a reinforcing member.

As shown in FIG. 2, the front pillar outer 2 has a substantially U-shaped cross section with an open upper part, and has a flange piece provided at an upper end thereof in a direction away from each other. Further, the reinforcement 3 has a substantially U-shaped cross-sectional shape in which walls facing each other overlap with the inner wall surface in the front pillar outer 2.

On the floor, a welding robot 6 and an intermediate electrode moving robot 7 are installed at positions facing each other with a jig and the work 1 interposed therebetween. Welding robot 6
Is a robot of a multi-axis type servo motor type, which has a spot welding gun 8 at the arm tip 6a, and can move the spot welding gun 8 to a hitting position where spot welding is performed by teaching performed in advance.

As shown in FIG. 2, the spot welding gun 8 is a so-called C-type welding gun, and includes a gun body 9 fixed to the arm tip 6a of the welding robot 6, and a fixed gun arm 10 fixed to the gun body 9. And a movable gun arm 11 whose tip is moved toward and away from the tip of the fixed gun arm 10 by the operation of an actuator (not shown) provided on the gun body 9.

Fixed gun arm 10 and movable gun arm 11
At the end of the front pillar outer 2 and ring reinforcement 3
And electrode tips 12 and 13 for spot welding the sandwiched portion by applying pressure and energizing.

The intermediate electrode moving robot 7 is a smaller, simpler and easier to control robot than the welding robot 6,
As shown in FIG. 1, an intermediate electrode 15 is provided at the arm tip 7a, and can be moved to and held at a hit point by teaching performed in advance.

The intermediate electrode 15 is formed of a copper metal material having conductivity in a relatively thick cubic shape, and has, on one side, a work contact surface 15 a that contacts the outer surface of the front pillar outer 2. On the other hand, there is an electrode contact surface 15b with which the electrode tip 13 contacts. In the present embodiment, since the outer surface of the front pillar outer 9 has a planar shape, the shape of the work contact surface 15a also has a corresponding planar shape.

When spot welding is performed between the front pillar outer 2 and the reinforcement 3, the intermediate electrode 15 is interposed between the outer surface of the front pillar outer 2 and the electrode tip 13, so that the indentation of the spot welding is reduced by the front pillar. It can be prevented from occurring on the outer surface of the outer 2.

FIG. 3 is a diagram schematically showing a control system of the spot welding apparatus. The spot welding device includes a spot welding control unit 21 for controlling the spot welding gun 8, a welding robot control unit 22 for controlling the welding robot 6, and an electrode moving robot control unit 23 for controlling the intermediate electrode moving robot 7. And are connected to each other so as to be able to input and output information signals.

In the electrode moving robot control unit 23, the workpiece contact surface 15a of the intermediate electrode 15 is
The intermediate electrode 1 so as to properly interview the hitting position on the outer surface of the
The holding position and orientation of 5 are stored by teaching, and the welding robot control unit 22 stores the hitting position for spot welding the front pillar outer 9 and the reinforcement 3 by teaching performed in advance.

Next, a spot welding method using the spot welding apparatus according to the present embodiment will be described. First, the electrode moving robot control unit 23 controls the intermediate electrode moving robot 7 based on a preset control program, and moves the intermediate electrode 15 to the first hitting position.

The intermediate electrode 15 is moved under the control of the intermediate electrode moving robot 7, and as shown in FIG.
Held in contact with the outer surface of the

When the intermediate electrode 15 is moved to the hitting position by the intermediate electrode moving robot 7, an intermediate electrode movement completion signal is output from the electrode moving robot control unit 23 to the welding robot control unit 22.

The welding robot controller 22 having received the intermediate electrode movement completion signal controls the welding robot 6 in accordance with the control program to move the spot welding gun 8 to the point where the intermediate electrode 15 is held.

The spot welding gun 8 is moved under the control of the welding robot 6 and, as shown in FIG.
And the tip of the movable gun arm 11 is held at a position facing the electrode contact surface 15 a of the intermediate electrode 15.

The spot welding gun 8 is operated by the welding robot 6.
Is moved to the hitting position and held, the welding robot control unit 22 outputs a spot welding gun movement completion signal to the spot welding control unit 21.

When the spot welding control unit 21 receives the spot welding gun movement completion signal from the welding robot control unit 22, it outputs a welding command signal to the spot welding gun 8.

The spot welding gun 8 having received the welding command signal operates the actuator to move the movable gun arm 11.
Is moved, and the intermediate electrode 15, the front pillar outer 2 and the reinforcement 3 are sandwiched and pressed between the electrode tips 12 and 13, and a current is applied to perform spot welding at the hitting position.

At this time, since the intermediate electrode 15 is interposed on the outer surface side of the front pillar outer 2 in a state where the intermediate electrode 15 is appropriately in contact with the outer surface, it is possible to prevent indentations on the outer surface due to spot welding.

The spot welding control section 21 terminates the spot welding, and controls the electrode tips 12 and 13 of the spot welding gun 8.
When a signal that is separated from the work 1 is input, a welding completion signal is output to the welding robot control unit 22.
3 and outputs a welding completion signal.

The electrode moving robot control unit 23 which has received the welding completion signal controls the intermediate electrode moving robot 7 to move the intermediate electrode 15 to the next hitting position. To move the spot welding gun 8 to the point where the intermediate electrode 15 has been moved.

The movement of the spot welding gun 8 and the intermediate electrode 15 and the spot welding are alternately repeated for each of the hit points, and when the spot welding at the preset hit points is completed, the welding control ends.

According to the above-described spot welding apparatus, the spot welding gun 8 is moved by the welding robot 6, and the intermediate electrode 15 is moved by the intermediate electrode moving robot 7. Accordingly, it is possible to easily cope with works having various shapes, and to make the spot welding apparatus versatile. Therefore, it is possible to easily cope with, for example, a case where the hit point position is changed due to a design change or a case where the number of hit points is increased or decreased.

It is sufficient that the intermediate electrode 15 is small and light in weight as compared with the spot welding gun 8 and that it can be held at the hitting position with such accuracy that the generation of indentations on the work 1 due to spot welding can be prevented. Since the required accuracy is low, a robot that has a simpler configuration and is easier to control than the welding robot 6 can be used as the intermediate electrode moving robot 7. Also, the spot welding gun 8 can use a relatively simple welding robot 6 without increasing the size. Therefore, the spot welding apparatus can be simplified.

Note that the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the spirit of the present invention. For example, in the above embodiment,
Although the intermediate electrode has a shape having a size corresponding to one hit point as an example, the intermediate electrode may have a shape having a size corresponding to a plurality of hit points.

According to this, after the first spot position is spot-welded, the next spot position can be spot-welded by moving only the spot welding gun 8 without moving the intermediate electrode 15. Thereby, the time for moving the intermediate electrode 15 can be shortened, and the work efficiency can be improved.

[0043]

As described above, according to the spot welding apparatus of the present invention, the spot welding gun is moved by the welding robot, and the intermediate electrode is moved by the intermediate electrode moving robot. The present invention can be easily adapted to a workpiece having the same, and the spot welding apparatus can be provided with versatility without requiring a special spot welding gun.

The intermediate electrode is lightweight and
It is only necessary to be able to maintain the hit point at an accuracy enough to prevent indentation on the workpiece due to spot welding, and since the required accuracy is low, the intermediate electrode moving robot should have a simple configuration and easy control. In addition, since a relatively simple welding robot can be used without increasing the size of the spot welding gun, the spot welding equipment can be simplified.

In another aspect of the present invention, since the intermediate electrode has a shape extending over a plurality of hit points, it is possible to continuously perform spot welding at a plurality of hit points while the intermediate electrode is fixed. it can. Therefore, spot welding at a plurality of locations can be performed in a shorter time, and work efficiency can be improved.

According to still another aspect of the present invention, since the contact surface of the intermediate electrode has a shape corresponding to the work, it can be surely brought into contact with the work, and the occurrence of indentation on the work by spot welding can be more effectively prevented. can do.

[Brief description of the drawings]

FIG. 1 is an overall view showing an embodiment.

FIG. 2 is an enlarged view of a main part as viewed from a direction A in FIG. 1;

FIG. 3 is a diagram schematically showing a control system of the spot welding apparatus.

FIG. 4 is a conventional explanatory diagram.

[Description of Signs] 1 Workpiece 6 Welding robot 7 Robot for moving intermediate electrode 8 Spot welding gun 15 Intermediate electrode

Claims (3)

[Claims] 1. A welding robot that supports a spot welding gun for performing spot welding by holding and pressing a work between the tips of a pair of gun arms and moves the spot welding gun to a hitting position. And a robot for moving the intermediate electrode to the hitting position while supporting an intermediate electrode that is pinched and pressed to prevent the generation of an indentation on the work. 2. The spot welding apparatus according to claim 1, wherein the intermediate electrode has a shape extending over a plurality of hit points. 3. The spot welding apparatus according to claim 1, wherein the intermediate electrode has a contact surface that contacts the work and has a shape corresponding to the work.