GB2083771A - Resistance spot welding gun - Google Patents

Abstract

An operation cylinder (1) carries a pair of cam plates (3,3) holding therebetween a stationary gun arm (2), and a gun arm holder (7) holding a movable gun arm (6) is connected through a pin (8) to a piston rod (5) of a piston (4) mounted in the operation cylinder, the gun arm holder (7) being in engagement through a further pin (9) with a cam grooves (10) which are formed in the cam plates and are each provided with a rectilinear and an arcuate section. In this way the movable gun arm when it is opened and closed is guided to move rectilinearly and arcuately producing, when opened, a large opening and, when closed, a nearly vertical pushing force to the workpiece. <IMAGE>

Description

SPECIFICATION Welding gun apparatus This invention relates chiefly to an electric resistance type welding gun apparatus used also for a clamp means.

An apparatus of this kind is, in general, so inconvenient that, if it has gun arms which are small in open degree, when a work (workpiece) to be welded is taken into the opening therebetween or taken out therefrom, the work is liable to hit the gun arms and result in damage to the same. For avoiding this inconvenience, there has been hitherto proposed that two pivot points should be provided for increasing the open degree, but this type is inconvenient in that the same is complicated in construction and becomes large in size and high in price.

This invention has for one of its objects to provide an apparatus free from those inconveniences, and it accordingly provides a welding gun apparatus wherein an operation cylinder is fixedly provided at its upper surface with a pair of right and left cam plates holding a stationary gun arm, and wherein there is provided, in a space formed between the cam plates, a gun arm holder holding a movable gun arm and connected through a pin to an upper end portion of a piston rod extending from a piston mounted in the operation cylinder, the gun arm holder being in engagement through at least one pin with a substantially L-shaped cam groove formed in each of the cam plates.

In this case, a gun body comprising the operation cylinder and the gun arms is required to be provided on a machine base so as to cooperate with a positioning member supporting from below a work (workpiece) to be worked.

This invention has for another object to provide an apparatus satisfying this requirement, and it is characterized in that a positioning member for supporting from below a work to be worked and a stopper plate having a guide rod extending therefrom downwards are provided on a supporting leg built on a machine base, and the operation cylinder is mounted slidably on the guide rod at such an intermediate position as positioned between the stopper plate and a stopper member provided below the stopper plate and is urged downwards by a spring.

Alt has been usual hitherto with this kind of apparatus that, when the work to be worked is changed into one different therefrom in shape an,d/or in welding point position, both the gun body and the positioning member have to be replaced by ones of other types, and thus there results such inconveniences that the working efficiency thereof becomes bad and the equipment cost becomes high.

This invention has for another object to provide an apparatus free from those inconveniences, and it is characterized in that the positioning member is detachably provided on the supporting leg, and the stopper plate is put on a seating base provided on a lower portion of the positioning member and is detachably connected thereto by a bolt so that the positioning member may be replaceable by another positioning member having a seating base.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a side view, partly in section, of one example of apparatus in accordance with this invention in an inoperative condition, Figure 2 is a similar view thereof in an operative condition, Figure 3 is a front view thereof, Figure 4 is a rear view of the same apparatus, Figures 5, 6 and 7 are sectional views taken along the lines V-V, VI-VI and VII-VII in Figure 2, and Figure 8 is a side view of the same apparatus but with a replaced positioning member.

Referring to the drawings, numeral 1 denotes an operation cylinder constituting a gun body, the cylinder 1 being fixedly provided at its upper surface with a pair of right and left cam plates 3, 3 holding a stationary gun arm 2. There is provided, in a space formed between the cam plates 3, 3, a gun arm holder 7 which is connected through a pin 8 to the top portion of a piston rod 5 extending from a piston 4 in the cylinder 1 and which gun arm holder 7 holds a movable gun arm 6 through a pin 9 in engagement with a substantially L-shaped cam groove 10 made in each of the cam plates 3, 3. The pin 8 is extended into the grooves 10, 10 for serving also as another engaging pin positioned below the pin 9. Numerals 8a, 9a denote guide rollers mounted on each end of the pins 8, 9.Numeral 2a denotes a bolt connecting the stationary gun arm 2 to the cam plates 3,3; numeral 3a denotes a bolt for connecting the cam plates 3, 3 to the operation cylinder 1; numeral 6a denotes a bolt for connecting the movable gun arm 6 to the gun arm holder 7; numeral 11 denotes a kickless cable extending along the rear side surface of the operation cylinder 1, the cable 11 being connected to the respective gun arms 2, 6 through respective electric supply plates 12a, 12b.

Referring again to the drawings, numeral 13 denotes a machine base, and numeral 14 denotes a supporting leg built on the machine base 13, and a positioning member 15 for supporting from below a work a to be worked and a stopper plate 17 having a guide rod 16 extending downwards are provided on the top portion of the supporting leg 14, and the operation cylinder 1, that is, the gun body is so mounted slidably on such an intermediate portion of the guide rod 16 as to be positioned between the stopper plate 17 and a stopper member 18 provided below the stopper plate 17, and is urged downwards by a spring 19.The rod 16 is inserted at its upper end through the plate 17 and is secured thereto by a nut 16a Now, the operation of the foregoing arrangement will be explained as follows: If the piston 4 in the operation cylinder 1 is moved upwards and downwards, the gun arm 6 is moved therewith through the gun arm holder 7 for opening and closing as shown in Figures 1 and 2. During this operation, the holder 7 is guided by the pins 8, 9 through the substantially L-shaped cam groove 9 on each side, and thus the gun arm 6 is given both a linear motion and an arcuate motion. In more detail, in the opening case, the same is first moved upwards nearly vertically and is then further moved outwards nearly arcuately, and thus a large open degree between the arms 2, 6 can be obtained.In the closing case, the same is first moved arcuately and is then moved straight downwards linearly, and consequently the closing thereof does not cause the work a to shift and, as occasion demands, the apparatus can be used as a clamp means.

Thus, according to this invention, the movable gun arm, when it is to be opened and closed, is guided by the pins through the substantially L-shaped cam grooves to move linearly and arcuately, so that the same, when opened, can produce a large open degree and, when closed, can give a nearly vertical pushing force to the work. The apparatus can thus be simplified in construction and lowered in price.

During the foregoing operation, the stationary gun arm 2 is urged downwards to be lowered by the spring 19 through the operation cylinder 1, so that there is a slight gap between the same and the work a as shown in Figure 1. When, however, the movable gun arm 6 is then operated and is brought into pressure contact with the upper surface of the work a, the stationary gun arm 2 is so influenced by a reaction force as to move upwards against the action of the spring 19, so that there is brought about such a condition that the two arms 2,6 clamp the work a firmly from above and below as shown in Figure 2.

According to this invention, further, in order to cope with any change in welding point position, it is arranged that the positioning member 15 is replaceable by another positioning member 15a as illustrated in Figure 8, for instance.

Namely, as shown clearly in Figure 7, the member 15 is mounted at its base end portion in a groove 20 made in the side surface of the supporting leg 14, and a clamping plate 21 is applied onto an outer surface of the member 15, the member 15 being detachably secured to the supporting leg 14 by a bolt 22 passing through those members. This is the case with the other member 15a as shown in Figure 8.

Further, the positioning member 15 is provided at its lower portion with a seating base 23, and the foregoing stopper plate 17 is put on the same and is detachably secured thereto by a bolt 24, the other member 15a being similarly provided with a seating base 23a. Furthermore, the guide rod 16 is connected at its lower end to a driving cylinder 25 so as to be movable upwards and downwards by the same, and further is slidably inserted through a universal joint 27 mounted on the forward end portion of a supporting arm 26 extending from the supporting leg 14, so that the rod 16 is tiltable forwards and rearwards at the joint 27 portion.

Numeral 28 denotes a bracket for supporting the driving cylinder 25.

Now, the operation of the foregoing arrangement will be explained as follows: The attached condition of the positioning member 15 is as shown, for instance, in Figure 1, and the welding position for the work a, that is, the welding point position is denoted by a point A. For changing this welding point position, the member 15 is replaced by the other member 15a.

In more detail, after the connection between the supporting base 23 of the member 15 and the stopper plate 17 of the guide rod 16 is released, the guide rod 16 is moved upwards together with the gun body 1 by the operation of the driving cylinder 25 so that the stopper plate 17 is moved to an upward position. Then, after the clamping plate 21 is detached and the member 15 is removed and is replaced by the other member 15a, the guide rod 16 is lowered and the stopper plate 17 is placed on the supporting base 23a of the member 15a and is secured thereto. This condition is shown in Figure 8.

Namely, the gun body 1 is in such a condition that it is in a posture inclined to the left together with the guide rod 16, and is in such a condition that the welding position for the work a, that is, the welding point position has been changed from the previous point A to an upper position point B.

Thus, according to this invention, the welding point position can be changed simply by replacing the positioning member, so that the foregoing inconvenience of a conventional one can be overcome.

Further, in the illustrated embodiment, the piston rod 5 is formed at its upper portion into a plateshaped section 5a having a shoulder region 5b at its lower end, so that the plate-shaped section 5a may serve so to cooperate with a stopper arm 17a extending from the stopper plate 17 as to be brought into turning lock engagement therewith, and the shoulder section 5b may serve so to cooperate with the stopper arm 17a as to separate an electrode of the stationary gun arm 2 from the work a, when the two members have been adhered together on welding.

Claims (7)

1. Awelding gun apparatus wherein an operation cylinder is fixedly provided at its upper surface with a pair of right and left cam plates holding a stationary gun arm, and wherein there is provided, in a space formed between the cam plates, a gun arm holder holding a movable gun arm and connected through a pin to an upper end portion of a piston rod extending from a piston mounted in the operation cylinder, the gun arm holder being in engagement through at least one pin with a substantially L-shaped cam groove formed in each of the cam plates.

2. Awelding gun apparatus as claimed in claim 1, wherein a positioning member for supporting from below a work (workpiece) to be worked and a stopper plate carrying a guide rod extending downwardly therefrom are provided on a supporting leg built on a machine base, and wherein the operation cylinder is mounted slidably on an intermediate portion of the guide rod positioned between the stopper plate and a stopper member provided below the stopper plate and is urged downwards by a spring.

3. Awelding gun apparatus as claimed in claim 2, wherein the positioning member is detachably provided on the supporting leg, and the stopper plate is put on a seating base provided on a lower portion of the positioning member and is detachably connected thereto by a bolt so that the positioning member is replaceable by another positioning member having a seating base.

4. Awelding gun apparatus as claimed in claim 3, wherein the guide rod is connected at its lower end to a driving cylinder so as to be movable upwards and downwards by the driving cylinder.

5. A welding gun apparatus as claimed in claim 4, wherein the guide rod is slidably inserted through a universal joint provided on the forward end portion of a supporting arm extending from the supporting leg.

6. Awelding gun apparatus as claimed in any of claims 2 to 5, wherein the piston rod is formed at its upper portion into a plate-shaped region having a shoulder region at its lower end, and wherein the plate-shaped region is formed so as to cooperate with a stopper arm extending from the stopper plate to prevent the piston rod from turning, the shoulder region being formed so as to cooperate with the arm to separate an electrode of the stationary gun arm from the work when the two members have been adhered together.

7. A welding gun apparatus substantially as hereinbefore described with reference to the accompanying drawings.