JPH09108844A - Resistance welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistance welding device different to develop component force in the lateral direction to an electrode chip. SOLUTION: In the resistance welding device arranging a piston rod 4 of a pressurizing cylinder 1 as the eccentric state to the center of the piston 3, the piston shape of the pressurizing cylinder 1 is made to non-circular form and the axis of the electrode ship 5 and the axis of the piston rod 4 are arranged on the same axial line. In this resistance welding device, the piston shape is desirable to form to almost elliptical shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding apparatus of the type that uses a pressure cylinder as a driving means for an electrode tip.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
When the pressure cylinder 12 interferes with the pressure cylinder 12, the center of the pressure cylinder 12 (same as the axis of the cylinder rod 14) and the center of the electrode tip 13 are eccentric. In addition, Japanese Utility Model Publication No. 49-13777 shows that the center of the pressure cylinder and the axis of the cylinder rod are eccentric, but even in such a case, the axis of the cylinder rod and the center of the electrode tip are It is eccentric.

[0003]

However, when the axial center of the cylinder rod and the center of the electrode tip are eccentric to each other, the electrode tip abuts against the object to be welded and pressurizes even when only thrust acts on the cylinder rod. When this occurs, a moment acts on the cylinder rod and the electrode tip, causing a lateral component force to act on the electrode tip, so slippage easily occurs between the objects to be welded or between the object to be welded and the electrode tip, and welding defects occur. It tends to occur. An object of the present invention is to provide a resistance welding device in which a lateral component force is less likely to act on the electrode tip during pressurization.

[0004]

The resistance welding apparatus of the present invention that achieves the above object is as follows. (1) In a resistance welding device in which the piston rod of the pressure cylinder is provided eccentrically from the center of the piston, the piston shape of the pressure cylinder is made non-circular, and the axis of the electrode tip and the axis of the piston rod are coaxial. A resistance welding device characterized by being provided. (2) The resistance welding device according to (1), wherein the piston shape of the pressure cylinder is substantially elliptical. (3) The resistance welding device according to (1), wherein a guide rod is provided at a position apart from the piston rod of the piston so as to be slidable with the piston. (4) The resistance welding device according to (1), wherein a piston rod is provided at a non-circular center of gravity of the piston.

In the device (1), since the piston of the pressure cylinder has a non-circular shape, the axis of the electrode tip and the axis of the piston rod can be easily provided on the coaxial line. Further, by providing the electrode tip and the piston rod in a coaxial line shape, when only the thrust acts on the piston rod when the electrode tip contacts the workpiece and pressurizes, the assembly of the piston rod and the electrode tip is provided. No moment is generated in the electrode tip and no lateral component force acts on the electrode tip. In the device of (2) above, since the piston shape is substantially elliptical, the eccentricity of the piston rod from the center of the piston can be increased by increasing the ratio of major axis / minor axis, and it can be welded to the pressurizing cylinder. Can effectively prevent interference. Further, in a multi-head welding apparatus in which a plurality of welding guns are arranged, interference between adjacent pressure cylinders is less likely to occur, and application is facilitated. In the device of the above (3), even if a moment is applied to the piston due to the eccentricity of the piston center and the piston rod, the piston does not rotate because it is guided by the guide rod,
Only the thrust force with no moment acts on the piston rod, so that the deflection of the electrode tip due to the rotation of the piston and the piston rod and the resulting lateral component force can be prevented. In the device of (4) above, since the piston rod is provided at the center of gravity of the non-circular shape of the piston,
A thrust force without a moment acts on the piston and the piston rod, and no lateral component force is generated on the electrode tip.

[0006]

1 and 2 show a first embodiment of the present invention, FIG. 3 shows a second embodiment of the present invention, and FIG. 4 shows a third embodiment of the present invention. . The parts common to all the embodiments of the present invention are denoted by the same reference numerals throughout the embodiments of the present invention. First, the configuration and operation common to all the embodiments of the present invention will be described with reference to, for example, FIGS. In FIGS. 1 and 2, one electrode tip 5 is attached to one end of a yoke 7 of a welding gun via a pressure cylinder 1, and the other electrode tip 6 is attached to the other end of the yoke 7. There is. The object 8 to be welded is pressed between the electrode tips 5 and 6, and an electric current is applied to the object 8 for resistance welding. The pressure cylinder 1 includes a cylinder casing 2 and
It comprises a piston 3 slidably accommodated therein, and a piston rod 4 connected to the piston 3 and extending through the cylinder casing 2 to the outside.

The shape of the piston 3 (the shape in the plane orthogonal to the piston axis) is non-circular. Conventionally, the cylinder is generally circular in cross section and the piston is also circular, but in the present invention, the piston 3 is non-circular. The piston rod 4 is eccentric from the center of the non-circular piston 3 and is connected to the piston 3. The axis of the electrode tip 5 and the axis of the piston rod 4 are provided on the same coaxial line. Further, the two electrodes 5 and 6 are on the same straight line.

The operation of the above configuration is as follows.
Since the piston rod 4 and the electrodes 5 and 6 are on a common axis and are offset from the center of the piston 3, the piston rod 4 should be offset from the center of the piston 3 to the side wall 8a side of the workpiece. This makes it possible to easily reduce the distance d between the outer surface of the pressurizing cylinder 1 on the side wall of the workpiece to be welded and the axis of the electrode tips 5 and 6, and to reduce the distance between the sidewall 8 a of the workpiece to be welded and the electrode tips 5 and 6. Even if f is small, it is possible to prevent the pressurizing cylinder 1 from interfering with the workpiece 8.

Further, since the electrode tips 5 and 6 and the piston rod 4 are provided on the coaxial line, the electrode tips 5 and 6 are
When only the thrust acts on the piston rod 4 when the workpiece 8 is pressed by (when no moment is applied from the piston 3 to the piston rod 4), the piston rod 4 and the electrode tip 5 attached thereto are No moment is generated in the assembly, and no lateral component force acts on the electrode tip 5. Therefore, the workpiece 8 and the electrode tips 5, 6 are
No slippage between the objects to be welded or slippage between the objects to be welded occurs, and welding defects caused thereby do not occur.

Next, the structure and operation of the parts peculiar to each embodiment of the present invention will be described. In the first embodiment of the present invention, as shown in FIGS. 1 and 2, the piston 3 of the pressure cylinder 1 has a substantially elliptical shape. The substantially oval shape includes a correct oval shape, an oval shape, a shape in which both ends of parallel lines are connected by a semicircle (as shown in FIG. 2), and the like. The effect is to increase the eccentricity of the piston rod 4 from the center of the piston by increasing the ratio of the major axis / minor axis of the substantially elliptical shape. It is possible to effectively approach the pressure cylinder 1 and the interference with the workpiece 8 of the pressure cylinder 1 as a result. Further, in the multi-head (multi-gun) welding apparatus in which a plurality of welding guns are arranged in parallel, the short diameter of the pressure cylinder 1 is small,
Interference between adjacent pressurizing cylinders 1 is less likely to occur, and this type of welding gun can be easily applied to a multi-head welding apparatus.

In the second embodiment of the present invention, as shown in FIG. 3, a guide rod 9 is provided at a position separated from the piston rod 4 of the piston 3 so as to be slidable with respect to the piston 3. The guide rod 9 extends parallel to the piston rod 4, and both ends of the guide rod 9 are fixed to the cylinder casing 2 of the pressurizing cylinder 1. The piston 3 is provided with a hole through which the guide rod 9 is inserted. The clearance between the inner periphery of this hole and the outer periphery of the guide rod 9 allows the piston 3 to slide but allows the piston 3 to almost tilt (rotate). The clearance is not allowed. As a result, the piston 3 is restrained from rotating and only reciprocates in the cylinder axis direction. Regarding the action, even if a moment acts on the piston due to the eccentricity between the center of pressure applied to the piston 3 (center of piston) and the center of reaction force from the piston rod 4 (center of piston rod), the piston 3 is guided by the guide rod 9 Since it is guided by the piston 3, the piston 3 does not tilt (does not rotate), so that only the thrust force without moment acts on the piston rod 4, and the piston and piston that may occur when the guide rod 9 is absent. The lateral deflection of the electrode tip 5 caused by the rotation of the rod and the lateral component force caused thereby are prevented.

In the third embodiment of the present invention, as shown in FIG. 4, the piston rod 4 is provided at the non-circular center of gravity of the piston 3. For example, if the shape of the piston 3 is an isosceles triangle with rounded apexes,
The center of gravity is located at the intersection of lines (three) connecting the apex angle and the center of the opposite side, and the piston rod 4 is connected to the piston 3 at that point. Regarding the action, since the point of application of the resultant force of the pressure applied to the piston 3 passes through the center of gravity of the piston shape, the resultant force of the pressure and the reaction force from the piston rod 4 act on the same axis with their directions opposite to each other. Therefore, the moment is essentially not applied to the piston and the piston rod when the electrode tip is pressed. Therefore, the electrode tip 5 caused by tilting (rotating) of the piston and the piston rod 5
It essentially prevents the lateral deflection and the resulting lateral component of force.

[0013]

According to the apparatus of the first aspect, since the piston has a non-circular shape, the axis of the electrode tip and the axis of the piston rod can be easily provided on the coaxial line, whereby the piston rod can be provided. It is possible to prevent a lateral component force from being applied to the electrode tip when only the thrust force acts. According to the apparatus of the second aspect, since the piston has a substantially elliptical shape, the width of the pressurizing cylinder can be reduced and the application to the multi-welding gun becomes easy. According to the apparatus of the third aspect, since the piston is slidably guided by the guide rod, the inclination of the piston can be suppressed and the lateral component force of the electrode tip due to this inclination can be prevented. According to the apparatus of claim 4, since the piston rod is provided at the center of gravity of the non-circular shape of the piston, the resultant force of the pressure and the reaction force from the piston rod act on the same axis line, and no moment is generated. Electrode tip lateral component force is essentially eliminated.

[Brief description of the drawings]

FIG. 1 is a side view showing a section of a pressure cylinder of a resistance welding apparatus according to a first embodiment of the present invention in section.

2 is a cross-sectional view of a portion of the pressure cylinder of FIG.

FIG. 3 is a side view showing a section of a pressure cylinder of a resistance welding apparatus according to a second embodiment of the present invention in section.

FIG. 4 is a cross-sectional view of a portion of a pressure cylinder of a resistance welding device according to a third embodiment of the present invention.

FIG. 5 is a side view showing a cross section of a pressure cylinder of a conventional resistance welding apparatus.

[Explanation of symbols]

 1 Pressurizing Cylinder 3 Piston 4 Piston Rod 5, 6 Electrode Tip 8 Workpiece 9 Guide Rod

Claims (4)

[Claims] 1. In a resistance welding apparatus in which a piston rod of a pressure cylinder is eccentrically provided from the center of the piston, the piston shape of the pressure cylinder is non-circular, and the axis of the electrode tip and the axis of the piston rod are coaxial. A resistance welding device characterized by being installed on the wire. 2. The resistance welding apparatus according to claim 1, wherein the piston of the pressure cylinder has a substantially elliptical shape. 3. The resistance welding apparatus according to claim 1, wherein a guide rod is provided on the piston at a position separated from the piston rod so as to be slidable with respect to the piston. 4. The resistance welding apparatus according to claim 1, wherein a piston rod is provided at a non-circular center of gravity of the piston.