JPH05253677A - Spot welding equipment - Google Patents

Abstract

PURPOSE:To make an energizing and heat generating part on materials to be welded coincident with the pressurizing position to increase the joining strength by holding a frame of a welding gun on a rotational holding means freely rotational around an axis passing a pressurizing and sandwiching point of electrodes. CONSTITUTION:The X-shaped frame 31 of the welding gun 30 is held on the holding means 41 freely rotational around the axis A passing the pressurizing and sandwiching point Po of the electrodes 35 and 36. Consequently, even when the welding surface of the materials 8 to be welded is not made orthogonal to the pressurizing direction of the electrodes, the frame 31 of the welding gun 30 is rotated around the axis A by the pressurizing force and the position of the welding gun 30 is corrected when the materials 8 to be welded are pressurized by the electrodes 35 and 36. Accordingly, the energizing and heat generating part and the electrode pressurizing position of the materials 8 to be welded are coincident with each other and a satisfactory weld zone is obtained. In addition, since the frame 31 of the welding gun 30 is supported elastically around the axis S by an elastic supporting means 51 provided on the holding means 41, the frame fitted with the electrodes does not become unsteady.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holding structure for a welding gun used for spot welding, and more particularly to a spot welding apparatus capable of performing optimum welding even when a workpiece is tilted with respect to an electrode. ..

[0002]

2. Description of the Related Art Portable spot welders are used when it is difficult to move a work piece to a large extent. The portable spot welder is composed of a welding gun, a secondary conductor, a welding transformer and a control device, and usually, only the welding gun is moved to perform welding work. Techniques for moving the welding gun along the object to be welded include, for example, SAIKAI Sho 58-4.
It is disclosed in Japanese Patent No. 7384.

FIG. 5 shows an example of spot welding work using a welding gun. In FIG. 5, 2 is a welding gun 1.
The C-shaped frame of FIG. 1 is shown, and the pressure cylinder 3 is attached to one of the C-shaped frames 2. Pressure cylinder 3
The upper electrode 4 is attached to the rod of 1 through an electrode holder. The lower electrode 5 is attached to the other side of the C-shaped frame 1 via an electrode holder. C-shaped frame 2
Are moved to respective welding points by, for example, the welding robot 7.

In the apparatus shown in FIG. 5, the work piece 8 is pressed by the upper electrode 4 and the lower electrode 5 by pushing down the upper electrode 4 by the pressure cylinder 3. In this state, a welding current is passed between the upper electrode 4 and the lower electrode 5, and spot welding of the workpiece 8 is performed. In the apparatus of FIG. 5, assuming that the workpiece 8 is not positioned at a predetermined position due to variations in accuracy, etc., the C-shaped frame 2 and the welding robot 7 are C-shaped due to the pressing force of the welding gun 1. A correction mechanism (equalizer) 9 for correcting the position of the frame 2 in the pressing direction is provided.

FIG. 6 shows an example of spot welding work in which a welding gun is applied to a multi-spot welding machine. Figure 6
In the figure, 11 indicates an X-shaped frame of the welding gun 10. The X-shaped frame 11 is composed of a frame 11a and a frame 11b.
Similarly to the scissors, b can swing around the fulcrum portion 12. The electrode 1 is provided on one of the frames 11a and 11b.
3, 14 are attached. Each frame 11a, 11
A pressure cylinder 15 is attached to the other side of b.
The rod 15b of the pressurizing cylinder 15 has one frame 1
The pressure cylinder body 11a is fixed to the other frame 11b.

The fulcrum 12 of the X-shaped frame 11 is swingably held by a support member 16. Support member 1
A base 17 is attached to the lower part of 6. The base 17 is fixed to a lower stand of a multi-spot welder (not shown). In the apparatus of FIG. 6, each electrode 1 is placed in a state in which the workpiece 8 is not positioned at a predetermined position.
When the object 8 to be welded is pressed by 3, 14, the X-shaped frame 11 is rotated about the fulcrum 12 by the applied pressure, and the posture of the welding gun 10 is corrected.

[0007]

However, in spot welding using a welding gun, the welding surface of the object to be welded is perpendicular to the electrode pressing direction due to variations in the accuracy of the object to be welded, defects in the welding equipment, or the like. In some cases, the following problems occur.

FIG. 8 shows the object to be welded 8 in the electrode pressing direction.
Shows that the welding surface of is not at a right angle. Figure 8
With respect to the inclination θ of the object 8 to be welded as shown in (1), the posture of the welding gun cannot be corrected even by the apparatus shown in FIGS. 5 and 6. Therefore, when the welding surface of the workpiece 8 is not at right angles to the electrode pressing direction, as shown in FIG. 9, the predetermined energizing heat generating portion S and the electrode pressing positions P ₁ and P ₂ do not match, Weld failure.

In view of the above problems, the present invention makes it possible to make the energizing heat generating portion and the electrode pressing position coincide with each other even when the welding surface of the workpiece is not perpendicular to the electrode pressing direction. An object is to provide a spot welding device.

[0010]

According to the spot welding apparatus of the present invention, the frame of a welding gun to which an electrode is attached is rotatable about an axis passing through a pressure clamping point of the electrode. The rotation holding means is provided with elastic support means for elastically supporting the frame of the welding gun around the axis.

[0011]

In the spot welding apparatus thus constructed, the frame of the welding gun is held by the holding means which is rotatable around the axis passing through the pressure nipping point of the electrode. As a result, even if the welding surface of the work piece is not perpendicular to the electrode pressing direction, when the work piece is pressed by the electrode, the welding gun frame rotates around the axis due to the applied pressure. However, the attitude of the welding gun is corrected. Therefore, it is possible to match the current-carrying heat generating portion of the object to be welded with the electrode pressing position, and a good welding portion can be obtained.

Further, since the frame of the welding gun is elastically supported around the axis by the elastic supporting means provided in the holding means, the frame to which the electrode is attached does not sway even when pressure is applied.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the spot welding apparatus according to the present invention will be described below with reference to the drawings.

First Embodiment FIGS. 1 to 3 show a first embodiment of the present invention.
Especially, the case where the welding gun is incorporated in the multi-spot welder is shown. In FIG. 1, 30 is an X-shaped frame 31.
2 shows a welding gun having The X-shaped frame 31 is
It is composed of a frame 32 and a frame 33, and each frame 32 and 33 is swingable around a fulcrum portion 34. Electrodes 35 and 36 are attached to one of the frames 32 and 33, respectively.

A pressure cylinder 37 is attached to the other of the frames 32 and 33. The rod 37b of the pressure cylinder 37 is connected to one frame 32, and the pressure cylinder body 37a is fixed to the other frame 33. Compressed air is supplied to the pressurizing cylinder 37 via an electromagnetic valve (not shown). The welding gun 30 pressurizes the workpiece 8 by the electrodes 35 and 36 when compressed air is introduced into the pressure cylinder 37.

A stopper screw 38 for adjusting the opening angle of the welding gun 30 is attached to the inside of each frame 32, 33. The fulcrum portion 34 of the welding gun 30 is held by a holding rod 40. The holding rod 40 has a function of swinging the welding gun 30 in the electrode pressing direction B around the fulcrum portion 34. The lower end of the holding rod 40 is held by the rotation holding means 41.

The rotation holding means 41 has a cylindrical shaft portion 42, a shaft portion 43, a bearing 44, and a base 45. Tubular shaft 4
2 is attached to the lower part of the holding rod 40, and the lower part is hollow. The base 45 is fixed to a lower base 50 of a multi-spot welder (not shown). The shaft portion 43 is attached to the base 45 via bolts 46. A bearing 44 is interposed between the shaft portion 43 and the tubular shaft portion 42.

The bearing 44 is composed of a tubular portion 44a and a collar portion 44b. The tubular portion 44a receives a radial load,
The collar 44b receives the thrust load.
That is, the entire load of the welding gun 30 acts on the bearing 44. The bearing 44 is made of a bearing metal having lubricity in this embodiment, but may be made of a combination of a ball bearing and a thrust bearing.

The tubular shaft portion 42, the shaft portion 43, and the bearing 44 are arranged on the axis A passing through the pressure nipping point P ₀ of the electrodes 35 and 36. As a result, the welding gun 30 is held rotatably around the axis A. The rotation holding means 41 is provided with elastic support means 51 for elastically supporting the X-shaped frame 31 of the welding gun 30 around the axis A.

The elastic support means 51 comprises a lever 52, a compression coil spring 53, an adjusting screw 54, a nut 55 and a screw receiving portion 56. The lever 52 is attached to the tubular shaft portion 42 of the rotation holding means 41 and is configured to rotate around the axis A together with the welding gun 30. A pair of screw receiving portions 56 are attached to the base 45. The pair of screw receiving portions 56 are arranged on both sides of the lever 52.

An adjusting screw 54 is screwed into the screw receiving portion 56. The adjusting screw 54 includes a nut 5 for preventing rotation.
5 is screwed. A compression coil spring 53 is attached to the tip of the adjusting screw 54. Lever 52
Is pressed by the compression coil spring 53 from both the left and right. The spring force of the compression coil spring 53 is
It is set to be smaller than the force for rotating the welding gun 30 around the axis A. As a result, the lever 52 can swing in the left-right direction against the biasing force of the compression coil spring 53. Thus, the X-shaped frame 31 of the welding gun 30 is elastically supported around the axis A by the elastic support means 51.

Next, the operation of the first embodiment will be described. When the object 8 to be welded is positioned at a predetermined position, compressed air is pressure-fed to the pressure cylinder 37 of the welding gun 30. As a result, the frame 32 and the frame 33 swing around the fulcrum portion 32 in the electrode pressing direction, and the workpiece 8 is pressed by the electrodes 35 and 36.

Here, when the welding surface of the object to be welded 8 is at right angles to the electrode pressing direction, as shown in FIG. 8, the energizing heat generating part S and the pressing directions P ₁ and P ₂ coincide with each other. Good spot welding of the workpiece 8 is performed. Due to variations in the accuracy of the work piece 8 and the like, the welding surface of the work piece 8 may have electrodes 35, 3
If it is not at right angles to the pressing direction of 6, the energizing heat generating portion S and the pressing positions P ₁ and P ₂ do not match, as in FIG. 9.

When the energizing heat generating part and the pressurizing position do not coincide with each other, as shown in FIG. 9, a reaction force N acts on the electrodes 35 and 36, and the energizing heat generating part S and the pressurizing positions P ₁ and P _{2 are applied.} The welding gun 30 rotates about the axis A until and are coincident with each other. That is, the welding gun 30 corrects its welding posture by its own pressure. As shown in FIG. 7, after the energization heat generating portion S and the pressurizing positions P ₁ and P ₂ match, the electrode 35 and the electrode 3
A welding current is applied to the welding target 6 and the welding target 8 to perform spot welding.

When the power supply to the workpiece 8 is finished, the compressed air sent into the pressurizing cylinder 37 is released to the atmosphere,
The pressure applied to the workpiece 8 by the electrodes 35 and 36 is released. In this state, one compression coil spring 53
The lever 52 that has been pressed to the side is pushed back by the urging force of the compression coil spring 53, and the X of the welding gun 30 is
The shaped frame 31 is rotated to the initial position. As described above, since the welding gun 30 is rotatable about the axis A, it is possible to constantly press the workpiece 8 from the right angle direction, and the joining strength of the spot welded portion can be increased as compared with the conventional case. ..

When a plurality of welding guns 30 are used for multi-spot welding, welding can be performed even when the shape of the work piece 8 is slightly different. ), A swinging device (not shown) for changing the posture of the welding gun 30 for each time is not required. Therefore, the cycle time of the welding operation can be shortened by the time the head swing device is driven.

Second Embodiment FIG. 4 shows a second embodiment of the present invention. The second embodiment differs from the first embodiment only in the type of welding gun, and the other parts are the same as those in the first embodiment. Therefore, the same parts as those in the first embodiment are designated by the same reference numerals. Description of parts will be omitted, and only different parts will be described.

In the first embodiment, the case of application to a welding gun having an X-shaped frame is shown, but in the present embodiment, the case of application to a welding gun having a C-shaped frame is shown.
In FIG. 4, reference numeral 60 denotes a welding gun having a C-shaped frame 61. The rotation holding means 41 is attached to the C-shaped frame 61 of the welding gun 60. The rotation holding means 41 has a function of holding the C-shaped frame 61 rotatably around an axis passing through the pressure nipping point P ₀ of the electrode. The rotation holding means 41 has a C-shaped frame 61 with an axis A.
Elastic support means 51 for elastically supporting the periphery is provided.

In the second embodiment thus constructed, the welding surface of the object 8 to be welded is the electrode 3 as in the first embodiment.
If the pressing directions of Nos. 5 and 36 are not at right angles, the C-shaped frame 61 is rotated about the axis A by its own pressure until the energizing heat generating portion and the pressing position coincide with each other, and the welding posture is corrected. Is performed.

In each of the above embodiments, the elastic support means 51 is used.
The rotary holding means 41 is arranged so as to be exposed to the outside.
The same effect can be obtained even if it is built in.

[0031]

According to the present invention, the following effects can be obtained. (1) The frame of the welding gun, to which the electrode is attached, is held by a rotation holding means that is rotatable around an axis passing through the pressure clamping point of the electrode, and the rotation holding means moves the frame of the welding gun around the axis. Since the elastic support means for elastically supporting the welding gun is provided, even if the welding surface of the workpiece is not at right angles to the electrode pressing direction, the welding gun frame can be used to adjust the attitude of the welding gun frame. Can be corrected.

(2) Therefore, it is possible to make the energizing heat generating portion and the pressing position of the work piece to coincide with each other, enhance the joint strength of the spot welding portion, and prevent deformation of the spot welding portion. it can.

[Brief description of drawings]

FIG. 1 is a front view of a welding gun in a spot welding apparatus according to a first embodiment of the present invention.

2 is a cross-sectional view of the device of FIG. 1 taken along the line ZZ.

FIG. 3 is a side view of FIG.

FIG. 4 is a front view of a welding gun in a spot welding apparatus according to a second embodiment of the present invention.

FIG. 5 is a front view of a conventional welding gun having a C-shaped frame.

FIG. 6 is a front view of a conventional welding gun having an X-shaped frame.

FIG. 7 is an enlarged plan view of a case where a current-carrying heating portion of a workpiece and a pressurizing position coincide with each other.

FIG. 8 is a perspective view showing a state in which the object to be welded is not perpendicular to the electrode pressing direction.

FIG. 9 is an enlarged plan view showing a state in which the current-carrying heating portion of the work to be welded and the pressing position do not match.

[Explanation of symbols]

8 Welding object 30 Welding gun 31 X-shaped frame 35, 36 Electrode 41 Rotation holding means 51 Elastic support means 60 Welding gun 61 C-shaped frame P ₀ Electrode pressure clamping point A axis

Claims (1)

[Claims] 1. A frame of a welding gun to which an electrode is attached is held by a rotation holding means which is rotatable about an axis passing through a pressure pinching point of the electrode, and the rotation holding means holds the welding gun's frame. A spot welding apparatus comprising elastic supporting means for elastically supporting the frame around the axis.