Clamp apparatus

Details Clamp apparatus Clamp apparatus

2000-04-12

2002-01-15

Watson, Robert C. (Department: 3723)

Work holders

With fluid means

Cylinder-piston means in series with additional positioning...

C269S027000, C269S228000

Reexamination Certificate

active

06338476

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a clamp apparatus capable of clamping a workpiece by using an arm which is rotatable by a predetermined angle in accordance with a driving action of a driving mechanism.
2. Description of the Related Art
The clamp cylinder has been hitherto used, for example, in order to clamp a constitutive part when the constitutive part of an automobile or the like is welded. Such a clamp cylinder is disclosed, for example, in U.S. Pat. No. 4,458,889.
The clamp cylinder disclosed in U.S. Pat. No. 4,458,889 is shown in
FIGS. 22 and 23
. A piston rod
2
is arranged movably back and forth between a pair of dividable bodies
1
a
,
1
b
. A coupling
3
is connected to one end of the piston rod
2
. A pair of links
5
a
,
5
b
and a pair of rollers
6
a
,
6
b
are attached rotatably by the aid of a first shaft
4
on both sides of the coupling
3
respectively. An arm
8
, which is rotatable by a predetermined angle, is connected between the pair of links
5
a
,
5
b
by the aid of a second shaft
7
.
In this arrangement, the pair of rollers
6
a
,
6
b
are provided rotatably by the aid of a plurality of needles
9
a
installed to a hole. The piston rod
2
is provided so that it is displaced integrally with the rollers
6
a
,
6
b
in accordance with the guiding action of the rollers
6
a
,
6
b
which make sliding movement along track grooves
9
b
formed on the bodies
1
a
,
1
b
respectively.
However, the clamp cylinder disclosed in U.S. Pat. No. 4,458,889 concerning the conventional technique described above involves the following inconvenience. That is, when an unillustrated workpiece is clamped by the arm
8
, the clamping force is decreased due to the change of the angle of rotation of the arm
8
.
In the case of the clamp cylinder described above, the reaction force, which is generated when the workpiece is clamped by the arm
8
, is applied to the first shaft
4
. Therefore, it is necessary to design the diameter of the first shaft
4
considering, for example, the surface pressure and the strength. As a result, an inconvenience arises in that the diameter of the first shaft
4
is increased.
Further, it is necessary to design the wall thickness and the diameter of the rollers
6
a
,
6
b
considering the surface pressure and the strength of the pair of rollers
6
a
,
6
b
which make sliding movement along the track grooves
9
b
. As a result, the following inconvenience arises. That is, the shape of the pair of rollers
6
a
,
6
b
is increased, in accordance with which the size of the bodies
1
a
,
1
b
is increased.
SUMMARY OF THE INVENTION
A general object of the present invention is to provide a clamp apparatus which makes it possible to maintain a substantially constant clamping force even when the angle of rotation of an arm is changed when a workpiece is clamped.
A principal object of the present invention is to provide a clamp apparatus which makes it possible to decrease the diameter of a knuckle pin by receiving the reaction force generated upon the clamping by using a guide roller.
Another object of the present invention is to provide a clamp apparatus which makes it possible to realize a small size of a body.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.


REFERENCES:
patent: 4458889 (1984-07-01), McPherson et al.
patent: 5996984 (1999-12-01), Takahashi

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