Work holders – With fluid means – Plural positioning means sequentially operated
Reexamination Certificate
2002-11-12
2003-12-16
Wilson, Lee D. (Department: 3723)
Work holders
With fluid means
Plural positioning means sequentially operated
C269S032000, C269S027000
Reexamination Certificate
active
06663093
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a clamp of the type that rotates a clamp rod.
2. Explanation of Related Art
There is a conventional technique of the rotary clamp of this type which is constructed in the following manner, as disclosed in U.S. Pat. No. 5,820,118.
A clamp rod is inserted into a cylinder tube rotatably around an axis and axially movably. The clamp rod has a halfway height portion in an outer periphery of which there are provided oppositely inclining two helical grooves and a straight groove. An engaging ball is fitted into any one of these three grooves. The engaging ball is supported by a recess provided in a barrel portion of the cylinder tube.
The conventional technique has the following problem.
The clamp rod is supported by the cylinder tube through one engaging ball. Therefore, the clamp rod slightly inclines when it is driven for clamping and for unclamping. This reduces the accuracy of placing a clamp member provided at a leading end of the clamp rod, at a clamping position and at an unclamping position.
SUMMARY OF THE INVENTION
The present invention aims at preventing the inclination of the clamp rod.
In order to achieve the above aim, for example, as shown in
FIGS. 1
to
6
or in
FIGS. 7
to
10
, the present invention has constructed a rotary clamp in the following manner.
A clamp rod
5
is inserted into a housing
3
rotatably around an axis and movably for clamping from one end to the other end in an axial direction. The clamp rod
5
has an outer peripheral portion formed with a plurality of guide groove
26
peripherally. The housing
3
supports a plurality of engaging members
29
which are fitted into these guide grooves
26
, respectively. Each of the guide grooves
26
comprises a rotary groove
27
and a straight groove
28
provided in continuity with each other from the other end to the one end in the axial direction. The rotary grooves
27
as well as the straight grooves
28
are arranged in parallel with one another. A partition wall between the adjacent guide grooves
26
,
26
has a minimum thickness (T) set to a value smaller than a groove width (W) of the guide groove
26
.
The present invention offers the following advantages.
The clamp rod is provided with the guide grooves into which the engaging members are fitted, respectively. This enables the housing to peripherally and substantially evenly support the clamp rod through the engaging members. Therefore, the clamp rod can be prevented from inclining when it is driven for clamping and for unclamping. This results in improving the accuracy of placing a clamp member provided at a leading end of the clamp rod, at a clamping position and at an unclamping position.
Further, the partition wall between the adjacent guide grooves has the minimum thickness set to the value smaller than the groove width of the guide groove. Therefore, it is possible to provide many guide grooves in the clamp rod so as to support the clamp rod peripherally and substantially evenly and at the same time to decrease an inclination angle of the rotary groove. This reduces the stroke required for rotating the clamp rod to result in making the rotary clamp compact. Besides, it becomes possible to arrange a plurality of engaging members, each of which has a large diameter, adjacent one another. Therefore, a rotary mechanism of the clamp can endure a large rotation torque to result in increasing its service lifetime.
The present invention includes a clamp in which the engaging member is formed from a ball. This invention can more smoothly rotate the clamp rod and increase the service lifetime of the rotary mechanism.
Further, in order to accomplish the foregoing object, the present invention has constructed a rotary clamp in the following manner, for example, as shown in
FIGS. 1
to
6
.
A clamp rod
5
is inserted into a housing
3
rotatably around an axis and movably for clamping from one end to the other end in an axial direction. The clamp rod
5
has an outer peripheral portion formed with a plurality of guide grooves
26
peripherally. The housing
3
supports a plurality of engaging balls
29
which are fitted into the guide grooves
26
, respectively. Each of the guide grooves
26
comprises a rotary groove
27
and a straight groove
28
provided in continuity with each other from the other end to the one end in the axial direction. The rotary grooves
27
as well as the straight grooves
28
are arranged in parallel with one another. A partition wall between the adjacent guide grooves
26
,
26
has a minimum thickness (T) set to a value smaller than a diameter (D) of the engaging ball
29
.
This invention also offers the same advantages as those of the above-mentioned invention.
The clamp rod can be prevented from inclining when it is driven for clamping and for unclamping. This results in improving the accuracy of placing a clamp member provided at a leading end of the clamp rod, at a clamping position and at an unclamping position. In addition, it is possible to reduce the stroke required for rotating the clamp rod, which leads to the possibility of making the rotary clamp compact. Besides, it becomes possible to arrange a plurality of engaging balls, each of which has a large diameter, adjacent one another. Therefore, a rotary mechanism of the clamp can endure a large rotation torque to result in increasing its service lifetime.
The present invention, for example, as shown in
FIGS. 1
to
4
or in
FIGS. 7
to
10
, includes the following clamp.
The engaging balls
29
are rotatably supported by through holes
31
provided in the housing
3
and a sleeve
35
is rotatably and externally fitted over the engaging balls
29
. This invention offers the following advantage.
When the clamp rod rotates, almost only rolling friction acts between an inner peripheral surface of the sleeve and the engaging balls, but sliding friction hardly acts therebetween. This reduces a resistance which acts from the sleeve to the engaging balls to result in decreasing a frictional force which acts from the engaging balls to the rotary grooves and therefore smoothly rotating the clamp rod with a light force.
The present invention also includes a clamp which is provided with at least three guide grooves. This invention is preferable due to the fact that it supports the clamp rod peripherally and substantially evenly and decreases the inclination angle of the rotary groove.
The present invention further includes a clamp which has the guide grooves arranged peripherally of the clamp rod at substantially the same spacing. This invention is preferable for supporting the clamp rod more evenly.
Moreover, the present invention, for instance, as shown in
FIG. 4
,
FIG. 5
or
FIG. 6
, includes the following clamp.
The clamp rod
5
has the other end potion provided with the above-mentioned guide grooves
26
. Each of the guide grooves
26
includes the rotary groove
27
provided at its other end portion with a stopper wall
45
which receives the engaging member or ball
29
. The stopper wall
45
has a receiving surface
45
a
which fits with the engaging member or ball
29
. This invention offers the following advantage. When the clamp rod rotates and retreats, the receiving surface of the stopper wall fits with the engaging member or ball to inhibit the clamp rod from rotating. This results in stopping the rotation of the clamp rod with a high accuracy.
Besides, the present invention, for example, as shown in
FIG. 1
, includes the following clamp. An annular piston
15
is inserted into the housing
3
axially movably. The clamp rod
5
is inserted into the piston
15
. A radial bearing
24
is arranged between the piston
15
and the clamp rod
5
. This invention offers another advantage of more smoothly rotating the clamp rod.
REFERENCES:
patent: 4351516 (1982-09-01), Ersoy et al.
patent: 4508327 (1985-04-01), Ersoy
patent: 5013015 (1991-05-01), Fatheree
patent: 5192058 (1993-03-01), VanDalsem et al.
patent: 5820118 (1998-10-01), Craft
patent: 5927700 (1999-07-01
Haruna Yosuke
Yokota Hideaki
Yonezawa Keitaro
Akin Gump Strauss Hauer & Feld L.L.P.
Kabushiki Kaisha Kosmek
Wilson Lee D.
LandOfFree
Rotary clamp does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotary clamp, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotary clamp will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3106713