JP2001105154A - Projection welding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection welding machine capable of securing parallel ism and coaxiality between an upper and lower electrodes independently of a pressurizing force at the welding time. SOLUTION: This projection welding machine has a C-shaped outer frame 10, an inner frame 20 which is formed as a separate member from the outer frame 10 and located at the inner side of the outer frame 10, a lower electrode 30 which is fixed on a lower arm 11 of the outer frame 10 or on a member fixed on the lower arm 11, an upper electrode 40 which is supported by the inner frame 20 and vertically movable with respect to the lower electrode 30, and a pressurizing device 50 which is fixed to an upper arm 13 of the outer frame 10 above the upper electrode 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a projection welding machine.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional projection welding machine comprises a C frame 1, a pressing device 2 having a vertically movable rod supported by an upper arm 1a of the C frame 1, and a pressing device. It has an upper electrode 3 attached to the lower end of the rod of the device 2, and a lower electrode 4 fixedly attached to the lower arm 1 b of the C frame 1 and arranged at a position facing the upper electrode 3. The upper electrode 3 is a pressing device 2
Is attached to the lower end of the rod by bolts and nuts (not shown).

[0003]

However, the above-mentioned conventional projection welding machine has the following problems. The positional relationship between the upper electrode 3 and the lower electrode 4 is C frame 1
Therefore, if a large pressing force is applied between the upper electrode 3 and the lower electrode 4, the C frame 1 may bend to the open side. When the C frame 1 bends, the degree of parallelism and the degree of coaxiality between the upper electrode 3 and the lower electrode 4 deteriorate, and there is a possibility that welding quality cannot be ensured. Further, since the upper electrode 3 is attached to the lower end of the pressurizing device 2 with bolts and nuts (not shown), it takes time to replace the upper electrode 3.
Further, it is difficult to obtain the parallelism and coaxiality between the upper electrode 3 and the lower electrode 4 after the replacement of the upper electrode 3. An object of the present invention is to provide a projection welding machine that can always maintain the parallelism and coaxiality between an upper electrode and a lower electrode regardless of the welding pressure. Another object of the present invention is to provide, in addition to the above objects, a projection welding machine in which electrodes can be easily replaced. Still another object of the present invention is to provide, in addition to the above objects, a projection welding machine in which the upper electrode and the lower electrode can be easily centered after electrode replacement.

[0004]

The present invention to achieve the above object is as follows. (1) A C-shaped outer frame, an inner frame formed separately from the outer frame and disposed inside the outer frame, and a lower arm of the outer frame or a member fixed to the lower arm. A projection including a lower electrode, an upper electrode supported by the inner frame and capable of moving up and down with respect to the lower electrode, and a pressurizing device attached to an upper arm of the outer frame above the upper electrode. Welding machine. (2) The projection welding machine according to (1), wherein the upper electrode is detachable from a guide groove formed on the inner frame and having one side opened. (3) The projection welding machine according to (1), wherein a lower end of a rod of the pressurizing device and an upper end of the upper electrode are formed into a shape capable of spherical fitting or taper fitting.

In the projection welding machine of the above (1), (2) or (3), since the upper electrode is supported by the inner frame formed separately from the outer frame, the welding force is applied to the outer frame. It does not affect the inner frame,
Even if the outer frame bends due to the reaction force of the welding pressure, the inner frame does not bend. By supporting the upper electrode on the inner frame and allowing it to move up and down independently of the bending of the outer frame, the parallelism and coaxiality of the upper electrode and the lower electrode can be always maintained. That is, the reaction force of the welding pressure can be handled by the outer frame, and the electrode accuracy can be ensured by the inner frame. In the projection welding machine of the above (2), since the upper electrode is detachable from the guide groove which is open on one side, the upper electrode can be set in the guide groove without using bolts and nuts. Easy. In the projection welding machine of the above (3), since the lower end of the rod of the pressurizing device and the upper end of the upper electrode are formed into a shape capable of spherical or taper fitting, the rod of the pressurizing device is pressed against the upper electrode. By contact, the center of the rod of the pressure device and the upper electrode can be automatically aligned.

[0006]

1 and 2 show a projection welding machine according to a first embodiment of the present invention, and FIG. 3 shows a projection welding machine according to a second embodiment of the present invention.
FIG. 4 shows a projection welding machine according to a third embodiment of the present invention. FIG. 5 shows the structure of the upper electrode support of the projection welding machine applicable to all embodiments of the present invention. Portions common to the first to third embodiments of the present invention are denoted by the same reference numerals throughout all embodiments.

First, the configuration and operation of a portion common to the first to third embodiments of the present invention will be described with reference to FIGS. 1, 2, and 5, for example. As shown in FIG. 1, the projection welding machine according to the embodiment of the present invention is fixed to a C-shaped outer frame 10, an inner frame 20 disposed inside the outer frame 10, and a lower arm 11 of the outer frame 10. A lower electrode 30 and an upper electrode 4 supported by the inner frame 20 and movable up and down with respect to the outer frame 10
0 and a pressing device 50 attached to the upper arm 13 of the outer frame 10.

The C-shaped outer frame 10 has a horizontal lower arm 11, an upper arm 13, and a connecting arm 12 connecting the lower arm 11 and the upper arm 13 and extending in the vertical direction. The upper arm 13 extends horizontally and is parallel to the lower arm 11 when no welding force is applied during welding.

The inner frame 20 is formed separately from the outer frame 10 and is arranged inside the outer frame. The inner frame 20 includes an upper plate 21, a support portion 23, and an upper plate 21.
And a connecting portion 22 extending vertically between the support portion 23 and the support portion 23. The upper plate 21 is parallel to the lower arm 11 of the outer frame 10. On the upper plate 21,
A guide groove 21a that is open on one side is formed, and an insulating collar 21b is provided along the guide groove 21a. As shown in FIGS. 2 and 5, the upper electrode 40 is detachably provided in the guide groove 21a. The lower electrode 30
As shown in FIG. 1, the outer frame 10 is fixedly attached to the lower arm 11 or to a pedestal portion 11 a fixed to the lower arm 11. The pedestal portion 11a forms a part of the lower arm 11.

The upper electrode 40 has a head 41 and a shaft 42. The upper electrode 40 is set on the upper plate 21 of the inner frame 20 by the shaft portion 42 being inserted into the guide groove 21 a from the open side of the guide groove 21 a and the lower surface of the head 41 engaging with the upper surface of the upper plate 21. . The upper electrode 40 is a lower electrode 3
0 can be moved up and down with respect to the inner frame 20.
It is supported by. Shaft core of upper electrode 40 and lower electrode 30
The upper electrode 40 is supported by the inner frame 20 so that the upper electrode 40 moves up and down while maintaining the state where the axes of the two coincide. This vertically movable structure allows the upper electrode 40 to be vertically movable with respect to the upper plate 21 of the inner frame 20 or to connect the upper plate 21 of the inner frame 20 to the connecting portion 2.
2, or the connecting portion 22 of the inner frame 20 can be slid vertically with respect to the support portion 23. The upper electrode 40 is floatingly supported by a spring member or a member 60 that exerts a spring action, and is urged upward (to a position where the upper electrode 40 does not come into contact with the lower electrode 30) when pushed down from a balanced position.

The pressurizing device 50 comprises, for example, a pressurizing cylinder (air cylinder, hydraulic cylinder, etc.) or a servomotor and a mechanism for converting the rotation of the servomotor into reciprocating motion (for example, a ball screw mechanism). In the illustrated example of the present invention, the case where the pressurizing device 50 includes a pressurizing cylinder is shown. As shown in FIG. 1, the pressure device 50 has a cylinder portion supported by the upper arm 13 of the outer frame 10. In the pressing device 50, when the pressing force during welding is not applied, the axis matches the axis of the lower electrode 30. The rod 51 of the pressurizing device 50 is movable vertically with respect to the outer frame 10.

Next, the operation will be described. At least one of the head 41 of the upper electrode 40 and the lower end of the rod 51 of the pressurizing device 50 has a spherical mechanism for absorbing the inclination of the upper electrode 40 and the rod 51 or the axial center of the upper electrode 40 and the rod 51 coincides with each other. Either of the taper mechanisms is formed. For example, the head 41 of the upper electrode 40 is formed with a concave portion 41a having a hemispherical shape or a tapered shape whose diameter becomes smaller as going downward, and is formed at the lower end of the rod 51 or a member fixed thereto. Is the concave portion 41a of the upper electrode 40
Convex portion 5 which can be fitted into a spherical surface or a taper.
1a is formed. However, the protrusion 5
1a may be formed, and the concave portion 41a may be formed in the rod 51.

As shown in FIG. 5, the upper electrode 40 is set in the guide groove 21a of the inner frame 20. At that time, the upper electrode 40 only needs to be inserted into the guide groove 21a,
It is not necessary to fix the upper electrode 40 to the upper plate 21 with bolts or the like after inserting the upper electrode 40 into the guide groove 21a. However, it may be fixed. Next, the pressure device 50 is operated to move the rod 51 downward, and the protrusion 51a at the lower end of the rod 51 and the concave portion 41a of the upper electrode 40 are spherically or taperedly fitted. Then, rod 5
1 is moved downward, a work (not shown) is sandwiched between the upper electrode 40 and the lower electrode 30, a welding pressure is applied to the work, and a welding current is applied to perform welding of the work.

In the projection welding machine according to the embodiment of the present invention, the inner frame 20 is provided separately from the outer frame 10, and the upper electrode 40 is supported by the inner frame 20 so as to be vertically movable with respect to the lower electrode 30. Since the electrode 30 is fixedly attached to the lower arm 11 or the pedestal portion 11 a of the outer frame 10, the reaction force of the welding force is received by the outer frame 10, and the reaction force of the welding force is not applied to the inner frame 20. Therefore, the inner frame 20 does not bend during welding and maintains the initial accuracy. That is, even when the outer frame 10 is bent by the welding press reaction force and the upper arm 13 is not parallel to the lower arm 11, the upper plate 21 and the lower arm 11 of the inner frame 20 remain parallel.

Further, since the upper electrode 40 is supported by the inner frame 20 so as to be slidable on the axis of the lower electrode 30, the upper electrode 4 is independent of the bending of the outer frame 10.
0 and the lower electrode 30 always have the same axis and are parallel. Therefore, the reaction force of the welding pressure is handled by the outer frame 10, and the alignment of the axes of the upper electrode 40 and the lower electrode 30 (electrode accuracy is ensured) is handled by the inner frame 20.

Further, when the upper electrode 40 and the rod 51 of the pressing device 50 are spherically fitted, even if the outer frame 10 bends and the axis of the rod 51 of the pressing device 50 and the upper electrode 40 are inclined, By absorbing the inclination, the pressing force of the pressing device 50 can be applied to the upper electrode 40 in the axial direction of the upper electrode 40. Therefore, a welding pressure is applied to the work vertically, and welding quality can be ensured. Further, when the upper electrode 40 and the rod 51 are taperedly fitted, when the upper electrode 40 is set in the guide groove 21a, a slight deviation occurs in the axis of the upper electrode 40 and the lower electrode 30 in plan view. The upper electrode 40 is automatically pressed by the pressing device 50 (rod 5).
The axis can be matched to the axis of 1) in a plan view, and can be automatically adjusted to or close to the axis of the lower electrode 30 in a plan view. When the upper electrode 40 and the rod 51 are spherically or tapered, the upper electrode 40
The energizing area between the rod and the rod 51 can be increased.

Next, parts unique 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, a concave portion 41 a is formed in the upper electrode 40, and a projection 51 a is formed in the rod 51 of the pressing device 50.
0 shows a case where the rod 51 is spherically fitted. Further, the connecting portion 22 of the inner frame 20 is formed of two (other than two) rod-shaped members, and is formed separately from the supporting portion 23. The connecting portion 22 is slidable up and down with respect to the supporting portion 23. A spring member 60 made of a compression spring is interposed between the upper plate 21 and the support portion 23, and floats and supports the upper plate 21 and the upper electrode 40 upward. The upper plate 21 and the upper electrode 40 are pushed downward against the upward urging force of the spring member 60 by the application of the welding pressure by the pressurizing device 50. At that time, the connecting portion 22
Slides into the support portion 23, the upper electrode 40 moves downward (toward the lower electrode 30) while maintaining a state where the axis is aligned with the axis of the lower electrode. When the welding pressure is removed, it returns to the position before the start of pressing down by the spring force.

In the second embodiment of the present invention, as shown in FIG.
A concave portion 41a is formed in the rod 51, and the upper electrode 40 and the rod 51 are taperedly fitted. Also,
The inner frame 20 has an upper plate 21, a connecting portion 22, and a supporting portion 23 integrally formed in a C shape. The upper electrode 40 is supported by the upper plate 21 of the inner frame 20 so as to be slidable in the vertical direction. The spring member 60 is made of a compression spring, and
The upper electrode 40 is interposed between the head 41 and the upper plate of the inner frame 20, and supports the upper electrode 40 in a floating manner. When the welding pressure is applied from the pressurizing device 50, the upper electrode 4
0 is pushed downward against the upward biasing force of the spring member 60, moves downward (to the lower electrode 30 side), and when the welding pressure is removed, the spring member 60 is returned to the position before being pushed down by the spring force. It is.

In the third embodiment of the present invention, as shown in FIG.
The projection 51a is formed on the rod 51, and the upper electrode 40 and the rod 51 are spherically fitted. The connecting portion 22 includes a rail 22a extending vertically upward from the support portion 23, and a guide 22b slidable on the rail 22a in the vertical direction. The upper plate 21 is attached to a guide 22b, and is movable up and down together with the guide 22b. The spring 60 is a compression spring, and is interposed between the upper plate 21 and the support 23. The upper plate 21 and the upper electrode 40 are pushed downward against the upward urging force of the spring member 60 by the application of the welding pressure from the pressing device 50. At this time, as the guide 22b moves downward along the rail 21a, the upper plate 21 and the upper electrode 40 move downward (lower) while keeping the upper electrode axis and the lower electrode axis aligned. (To the electrode 30 side). When the welding pressure is removed, the upper electrode 40 is returned to the position before being pushed down by the spring force.

[0020]

According to the present invention, claim 1 or claim 2 or claim 3 is provided.
According to the projection welding machine described above, since the upper electrode is supported by the inner frame formed separately from the outer frame, the welding force is not applied to the inner frame because the welding force reaction force is applied to the outer frame. Even if the outer frame bends due to the reaction force of the above, the inner frame does not bend. By supporting the upper electrode on the inner frame and allowing it to move up and down independently of the bending of the outer frame, the parallelism and coaxiality of the upper electrode and the lower electrode can be always maintained. That is, the reaction force of the welding pressure can be handled by the outer frame, and the electrode accuracy can be ensured by the inner frame. According to the projection welding machine of claim 2, since the upper electrode is detachable from the guide groove having one side opened, the upper electrode can be set in the guide groove without using bolts and nuts. It is easy to attach and detach. According to the projection welding machine of the third aspect, since the lower end of the rod of the pressurizing device and the upper end of the upper electrode are formed into a shape capable of spherical or taper fitting, the rod of the pressurizing device is connected to the upper electrode. , The rod of the pressure device and the upper electrode can be automatically aligned.

[Brief description of the drawings]

FIG. 1 is a side view of a projection welding machine according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the upper electrode and its vicinity in the projection welding machine according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing an inner frame and a rod portion of a pressurizing device of a projection welding machine according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a lower end portion of an inner frame and a rod of a pressing device of a projection welding machine according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view of an upper plate and an upper electrode applicable to all embodiments of the present invention.

FIG. 6 is a side view of a conventional projection welding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Outer frame 11 Lower arm 13 Upper arm 20 Inner frame 21 Upper plate 21a Guide groove 22 Connecting part 23 Supporting part 30 Lower electrode 40 Upper electrode 41a Depression 50 Pressure device 51 Rod 51a Projection 60 Spring member

Claims (3)

[Claims] 1. A C-shaped outer frame, an inner frame formed separately from the outer frame and arranged inside the outer frame, and fixed to a lower arm of the outer frame or a member fixed to the lower arm. A lower electrode supported by the inner frame, and an upper electrode movable up and down with respect to the lower electrode; and a pressurizing device attached to an upper arm of the outer frame above the upper electrode. Having a projection welding machine. 2. The projection welding machine according to claim 1, wherein the upper electrode is detachable from a guide groove formed on the inner frame and having one side opened. 3. The projection welding machine according to claim 1, wherein a lower end of the rod of the pressurizing device and an upper end of the upper electrode are formed into a shape capable of spherical or tapered fitting.