Work holders – Work-underlying support – Support mounting means
Reexamination Certificate
2001-11-14
2003-09-16
Hail, III, Joseph J. (Department: 3723)
Work holders
Work-underlying support
Support mounting means
C269S032000, C269S310000
Reexamination Certificate
active
06619646
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a clamping apparatus and more particularly to a clamping apparatus of the type that pulls a driven rod through a plurality of transmission members by an annular driving member.
2. Explanation of Related Art
A conventional example of the clamping apparatus of this type is recited in Japanese Patent Public Disclosure No. 9-285925 proposed earlier by the Assignee of the present invention. The conventional example is constructed as follows.
A driven rod is inserted into a tubular bore of a sleeve. The driven rod has one end portion provided with an input portion in the shape of a short column. A plurality of transmission balls are inserted into the other end portion of a peripheral wall of the sleeve and spaced apart from each other peripherally at a predetermined interval outside the other end of the input portion. These transmission balls are radially movable. When clamping, an operation cam externally fitted onto the sleeve moves the transmission balls radially inwards to make them engage with the input portion. The sleeve pulls the driven rod toward the one end through the transmission balls.
The conventional technique is excellent in that the operation cam can smoothly and reliably switch over the transmission balls to an engageable position. However, each of the transmission balls is brought into contact with the input portion almost as it makes a point contact therewith to result in limiting a transmission force. Therefore, it still has to be improved for strongly pulling the driven rod.
SUMMARY OF THE INVENTION
The present invention has an object to provide a clamping apparatus which exerts a strong pulling force.
In order to accomplish the above-mentioned object, the present invention has constructed a clamping apparatus in the following manner, for example, as shown in
FIGS. 1
to
5
.
An annular driving member
11
is axially movably inserted into a housing
4
. The driving member
11
has a tubular bore
11
a
into which a driven rod
6
is inserted. The driven rod
6
is provided, at a portion near one end, with an input portion
6
a
. A plurality of transmission members
15
are arranged peripherally side by side around the input portion
6
a
. Each of the transmission members
15
is provided, at a portion close to the other end, with an engaging portion
17
which engages with the input portion
6
a
. The transmission members
15
can switch over between an engageable position (X) where the engaging portions
17
axially face the input portion
6
a
when the transmission members
15
swing radially inwards and a disengaging position (Y) where the facing is cancelled when they swing radially outwards. The transmission members
15
at the engageable position (X) are movable toward the one end by the driving member
11
. The transmission members
15
swing from the disengaging position (Y) to the engageable position (X) by a first actuation means
26
and they swing from the engageable position (X) to the disengaging position (Y) by a second actuation means
32
.
The present invention operates in the following manner, for example, as shown in
FIGS. 2
to
4
.
Under an unclamping condition shown in
FIG. 2
, the driving member
11
moves downwards, namely in a direction to the other end. The respective transmission members
15
switch over to the radially outward disengaging position (Y) by the second actuation means
32
.
When driving the driven rod
6
for clamping, first, as shown in
FIG. 3
, the first actuation means
26
swings the transmission members
15
to the radially inward engageable position (X). This allows the engaging portions
17
provided in the transmission members
15
to face the input portion
6
a
from below. Subsequently, as shown in
FIG. 4
, the driving member
11
drives the transmission members
15
at the engageable position (X) upwards. This enables the engaging portion
17
of every transmission member
15
to push the input portion
6
a
upwards with the result of strongly pulling the driven rod
6
upwards.
The driven rod
6
is driven for unclamping by procedures substantially opposite to the above ones.
In consequence, the present invention offers the following advantages.
The plurality of transmission members are peripherally arranged side by side around the input portion of the driven rod. They swing radially inwards and then switch over to the engageable position. This allows the engaging portions of these transmission members to face the input portion so that they can make surface contact over substantially the whole periphery of the input portion. Accordingly, these transmission members can strongly pull the driven rod to result in the possibility of providing a strong clamping apparatus.
Besides, the transmission members swing so as to switch over between the engageable position and the disengaging position. This can reduce the strokes for engagement and disengagement of the first and the second actuation means in correspondence with a lever ratio for swinging the transmission members with the result of being able to make the clamping apparatus compact.
Further, the transmission members are arranged around the input portion of the driven rod. This can make the input portion and the transmission members axially overlap with each other. Therefore, the entire length of the housing can be shortened by an amount corresponding to the overlap to result in the possibility of making the clamping apparatus more compact.
The present invention includes the following clamping apparatus.
Each of the transmission members
15
has a portion near one end, which is provided on its outer peripheral portion with a fulcrum portion
16
swingably supported by the housing
4
and has another portion close to the other end, which is provided on its outer peripheral portion with a first portion
18
to be actuated for engagement. The first actuation means
26
is connected to the first portion
18
. The portion near one end of every transmission member
15
is provided on its inner peripheral portion with a second portion
19
to be actuated for disengagement. The second actuation means
32
is connected to the second portion
19
.
The above-mentioned invention positions the first portion to be actuated and the second portion to be actuated, radially eccentric from each other. This prevents the first and the second actuation means from being arranged in series axially to result in the possibility of reducing the axial length of the clamping apparatus.
The present invention furthermore includes the following clamping apparatus.
The second actuation means
32
comprises a push member
30
which is brought into contact with the second portions
19
of the transmission members
15
, and a resilient member
31
which pushes the push member
30
toward the other end. This invention can make the second actuation means simple and compact to result in greatly downsizing the clamping apparatus.
The present invention still more includes the following clamping apparatus.
The driving member
11
comprises a fluid pressure piston. A fluid pressure actuation chamber
12
is formed between the driving member
11
and the other end wall
4
a
of the housing
4
. Further, a return spring
13
is attached between the driving member
11
and one end wall
4
b
of the housing
4
. The first actuation means
26
is provided with a slant cam
27
connected to the driving member
11
. This invention can drive both of the driving member and the slant cam through pressurized fluid of the fluid pressure actuation chamber with the result of being able to form the clamping apparatus into a simple structure.
REFERENCES:
patent: 5971380 (1999-10-01), Hebener
patent: 6024354 (2000-02-01), Yonezawa
patent: 6095509 (2000-08-01), Yonezawa
patent: 6101888 (2000-08-01), Yonezawa
patent: 42 00 365 (1993-07-01), None
patent: 0 319 710 (1989-06-01), None
patent: 0 803 316 (1997-10-01), None
Bacon & Thomas PLLC
Hail III Joseph J.
Kabushiki Kaisha Kosmek
Shanley Daniel
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