Information
-
Patent Grant
-
6666440
-
Patent Number
6,666,440
-
Date Filed
Monday, November 18, 200222 years ago
-
Date Issued
Tuesday, December 23, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Akin, Gump, Strauss, Hauer & Feld, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 269 20
- 269 24
- 269 32
- 269 25
- 254 93 H
- 029 252
-
International Classifications
-
Abstract
A housing (3) has an upper end wall (3a) and a lower end wall (3b) which support an upper slide portion (11) and a lower slide portion (12) of a clamp rod (5) vertically movably, respectively. The rod (5) is moved downwards for clamping through a clamp spring (20). The lower slide portion (12) has an outer periphery provided with guide grooves (26), each of which comprises a helical rotary groove (27) and a straight groove (28), peripherally in plural number. Engaging balls (29) which are fitted into the respective guide grooves (26) are rotatably supported by through holes (31) provided in an upper portion of the lower end wall (3b). A sleeve (35) is externally fitted over the engaging balls (29) rotatably around an axis.
Description
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 housing, an upper wall of which supports a halfway height portion of the clamp rod vertically movably. The clamp rod has a lower portion provided with a piston which is vertically movably supported by a barrel portion of the housing. The clamp rod is formed with a cam groove on an upper side of the piston. An engaging ball to be fitted into the cam groove is inserted into a recess provided in the barrel portion of the housing.
The conventional technique had a problem of being unable to smoothly rotate the clamp rod because a large frictional force acts from the engaging ball to the cam groove when rotating the clamp rod.
SUMMARY OF THE INVENTION
The present invention has an object to provide a clamp in which a clamp rod smoothly rotates.
In order to accomplish the above object, the present invention has constructed a rotary clamp in the following manner.
For example, as shown in
FIGS. 1
to
4
or in
FIGS. 7
to
10
, a housing
3
supports a clamp rod
5
axially movably and rotatably around the axis. The clamp rod
5
is made movable for clamping from a first end wall
3
a
of the housing
3
to a second end wall
3
b
thereof. Within the housing
3
, the clamp rod
5
has an outer periphery provided with guide grooves
26
peripherally in plural number. Each of the guide grooves
26
comprises a rotary groove
27
and a straight groove
28
which are provided in continuity with each other from the second end wall
3
b
to the first end wall
3
a
. Engaging balls
29
to be fitted into the respective guide grooves
26
are rotatably supported by through holes
31
provided in the housing
3
. A sleeve
35
is externally fitted over the engaging balls
29
rotatably around the axis.
The above-mentioned invention offers the following advantage.
When the clamp rod rotates, for instance, in a clockwise direction when seen in plan, the engaging balls fitted into the rotary grooves of the clamp rod roll in a counter-clockwise direction when seen in plan. Simultaneously, the sleeve externally fitted over the engaging balls freely rotates in the counter-clockwise direction. This allows almost only rolling friction to act between an inner peripheral surface of the sleeve and every engaging ball, but hardly allows sliding friction to act therebetween. Therefore, a resistance which acts from the sleeve to every engaging ball is decreased. As a result, a frictional force which acts from every engaging ball to the rotary groove is reduced, thereby smoothly rotating the clamp rod with a light force.
The present invention includes the following rotary clamp.
For instance, as shown in
FIGS. 1
to
4
or in
FIGS. 7
to
10
, the second end wall
3
b
of the housing
3
is constituted by a support cylinder
13
. The clamp rod
5
is inserted into an inner wall
13
a
of the support cylinder
13
. And the inner wall
13
a
is provided with the through holes
31
. This invention has inserted the clamp rod into the inner wall of the support cylinder, which results in being able to form the inserted portion into a structure of a reduced diameter and decrease an inclination angle of the rotary groove. In consequence, it is possible to reduce the stroke required for rotating the clamp rod, thereby making the rotary clamp compact.
Further, the present invention includes the following rotary clamp.
For example, as shown in
FIGS. 1
to
4
, 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 these piston
15
and clamp rod
5
. This invention offers an advantage of being able to rotate the clamp rod more smoothly.
Moreover, the present invention includes the following rotary clamp.
For instance, as shown in
FIGS. 1
to
4
, the piston
15
faces an input portion
14
of the clamp rod
5
from a side of the first end wall
3
a
. There is provided between the piston
15
and the first end wall
3
a
, a first chamber
21
in which a clamp spring
20
is attached. And there is provided between the piston
15
and the second end wall
3
b
, a second chamber
22
to which pressurized fluid for unclamping is supplied. This invention offers the following advantage.
Upon unclamping, a force which has acted from the pressurized fluid in the second chamber to the piston is not applied to the clamp rod. This prevents an excessive force from acting on the rotary grooves and the engaging balls. Therefore, a rotary mechanism which comprises the rotary grooves and the engaging balls increases its service lifetime.
In addition, the present invention includes the following rotary clamp.
For example, as shown in
FIGS. 7
to
10
, the piston
15
faces an input portion
14
of the clamp rod
5
from a side of the first end wall
3
a
. There is provided between the piston
15
and the first end wall
3
a
, a first chamber
21
to which pressurized fluid for clamping is supplied. And there is also provided between the piston
15
and the second end wall
3
b
, a second chamber
22
to which pressurized fluid for unclamping is supplied. This invention offers the following advantage as well as the above-mentioned invention.
Upon unclamping, a force which has acted from the pressurized fluid in the second chamber to the piston is not applied to the clamp rod. This prevents an excessive force from acting on the rotary grooves and the engaging balls. Therefore, a rotary mechanism which comprises the rotary grooves and the engaging balls increases its service lifetime.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1
to
4
show a first embodiment of the present invention;
FIG. 1
is a partial sectional view of a rotary clamp when seen in elevation;
FIG. 2
is a sectional view of a rotary mechanism provided in the clamp when seen in plan;
FIG. 3
is an enlarged view of an essential portion in FIG.
1
and corresponds to a sectional view when seen along a line III—III in
FIG. 2
in a direction indicated by arrows;
FIG. 4
is an enlarged and developed view of a lower slide portion provided in a clamp rod of the clamp;
FIG. 5
shows a first modification of the first embodiment and is similar to
FIG. 4
;
FIG. 6
shows a second modification of the first embodiment and is similar to
FIG. 4
;
FIGS. 7
to
10
show a second embodiment of the present invention;
FIG. 7
is a partial sectional view of the clamp when seen in elevation and is similar to
FIG. 1
;
FIG. 8
is a sectional view of a rotary mechanism provided in the clamp when seen in plan and is similar to
FIG. 2
;
FIG. 9
is an enlarged view of an essential portion in FIG.
7
and corresponds to a sectional view when seen along a line
1
X—
1
X in
FIG. 8
in a direction indicated by arrows; and
FIG. 10
is an enlarged and developed view of a lower slide portion provided in a clamp rod of the clamp and is similar to FIG.
4
.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A first embodiment of the present invention is explained with reference to
FIGS. 1
to
4
. First, an explanation is given for a whole structure of a rotary clamp by resorting to FIG.
1
.
FIG. 1
is a partial sectional view of the clamp when seen in elevation.
A housing
3
of a clamp
2
is fixed to a work pallet
1
through a plurality of bolts (not shown). The housing
3
has a cylindrical hole
4
into which a clamp rod
5
is inserted. The clamp rod
5
has an upper end portion to which an arm
6
is secured at a desired rotation position by a nut
7
. The arm
6
has a leading end portion to which a push bolt
8
is fixed.
The housing
3
has an upper end wall (first end wall)
3
a
which supports an upper slide portion (first slide portion)
11
provided in a rod main body
5
a
of the clamp rod
5
slidably and hermetically. Further, a support cylinder
13
forms part of a lower end wall (second end wall)
3
b
of the housing
3
and slidably supports a lower slide portion (second slide portion)
12
which projects downwards of the rod main body
5
a
. The upper slide portion
11
and the lower slide portion
12
are tightly fitted into the upper end wall
3
a
and the lower end wall
3
b
, respectively.
The lower slide portion
12
has an outer diameter set to a value smaller than that of an outer diameter of the upper slide portion
11
.
A means for driving the clamp rod
5
is constructed as follows.
The clamp rod
5
is provided with an input portion
14
in the shape of a flange between the upper slide portion
11
and the lower slide portion
12
. Further, an annular piston
15
is externally fitted onto the clamp rod
5
vertically movably and hermetically through a sealing member
16
. The piston
15
faces the input portion
14
from above. And the piston
15
is inserted into the cylindrical hole
4
hermetically through another sealing member
15
a.
In addition, a radial bearing
24
is arranged between the input portion
14
and the piston
15
. A snap ring
25
prevents the removal of the piston
15
. Here the radial bearing
24
is composed of many metal balls and can receive not only a radial force but also a vertical thrust.
A first chamber
21
for clamping is provided between the piston
15
and the upper end wall
3
a
. A clamp spring
20
made of a compressed coil spring is attached in the first chamber
21
. A second chamber
22
for unclamping is provided between the piston
15
and the lower end wall
3
b
. Pressurized oil is supplied to and discharged from the second chamber
22
through a pressurized oil supply and discharge port
19
for unclamping and a restricting oil passage
18
.
A fitting gap (G) between a peripheral wall of the second chamber
22
and an outer peripheral surface of the piston
15
limits supply amount of pressurized oil from the oil passage
18
to the second chamber
22
as well as discharge amount of the pressurized oil from the second chamber
22
to the oil passage
18
.
A rotary mechanism is provided over the lower slide portion
12
of the clamp rod
5
and an upper portion of an inner wall
13
a
of the support cylinder
13
. The rotary mechanism is constructed in the following manner as shown in FIG.
1
and
FIG. 2
to FIG.
4
.
FIG. 2
is a sectional view of the rotary mechanism when seen in plan.
FIG. 3
is an enlarged view of an essential portion in FIG.
1
and corresponds to a sectional view when seen along a line III—III in
FIG. 2
in a direction indicated by arrows.
FIG. 4
is an enlarged and developed view of an outer peripheral surface of the lower slide portion
12
.
The lower slide portion
12
has the outer peripheral surface provided with three guide grooves
26
peripherally at substantially the same spacing. Each of the guide grooves
26
is formed from a groove in the shape of an arc or a segment when seen in section. And it comprises a helical rotary groove
27
and a straight groove
28
which is in upward continuity with the helical rotary groove
27
. The rotary grooves
27
as well as the straight grooves
28
are arranged in parallel with one another. As for the adjacent guide grooves
26
,
26
, a partition wall is minimum in thickness between a lower portion of a right rotary groove
27
and an upper portion of a left rotary groove
27
in FIG.
4
. The minimum thickness (M) of the partition wall is set to a value smaller than a groove width (W) of the guide groove
26
. Further, the rotary groove
27
is inclined at an angle (A) which is set to a small value within a range of about 11 degrees to about 25 degrees. In the exemplified clamp which relies on a spring force, the inclination angle (A) is preferably set to a value within a range of about 11 degrees to about 20 degrees for reducing the rotation stroke.
As such the inclination angle (A) of the helical rotary groove
27
has been made small to result in largely shortening a lead of the rotary groove
27
. This decreases the stroke for rotating the clamp rod
5
.
An engaging ball
29
is fitted into each of the guide grooves
26
. Numeral
29
a
in
FIGS. 3 and 4
designates a fitting portion of the engaging ball
29
. The engaging ball
29
has a diameter (D) (see
FIG. 3
) set to a value larger than the minimum thickness (M) of the partition wall between the adjacent rotary grooves
27
,
27
. The respective engaging balls
29
are rotatably supported by three through holes
31
provided in the upper portion of the inner wall
13
a
of the support cylinder
13
. A sleeve
35
is externally fitted over these three engaging balls
29
rotatably around the axis. Speaking it in more detail, the sleeve
35
has an inner peripheral surface formed with a groove
36
in the shape of a letter ‘V’. The V-shaped groove
36
has two vertical points at which the engaging ball
29
can roll.
The engaging ball
29
is inserted into the through hole
31
via an internally threaded hole
49
which is provided in the sleeve
35
. A closure bolt
50
is attached to the internally threaded hole
49
. A projection
50
a
at a leading end of the closure bolt
50
can receive the engaging ball
29
.
The rotary groove
27
has a lower end portion provided with a stopper wall
45
which receives the fitting portion
29
a
of the engaging ball
29
. The stopper wall
45
has a receiving surface
45
a
which can fit with the engaging ball
29
.
Besides, the guide groove
26
has an opening which is provided at its edge portion with a cutting surface
34
for preventing interference. Owing to this arrangement, even if the opening edge portion of the guide groove
26
undergoes a plastic deformation by a surface pressure of the engaging ball
29
and heaps up, it is possible to prevent the interference between the heaped-up portion and the inner wall
13
a
of the support cylinder
13
. As a result, the clamp rod
5
smoothly rotates for a long period of time.
Further, as shown in
FIG. 1
, an outer wall
13
b
of the support cylinder
13
is attached to a barrel portion
3
c
of the housing
3
through a positioning pin
38
which extends vertically, so as to be prevented from rotating. This makes it possible to accurately determine a rotation phase of the clamp rod
5
with respect to the housing
3
. The support cylinder
13
is secured to the housing barrel portion
3
c
by a lock member
39
made of a snap ring.
The rotary clamp
2
operates as follows.
In a state of
FIG. 1
, pressurized oil is supplied to the second chamber
22
for unclamping, thereby raising the clamp rod
5
to an illustrated rotation and retreat position.
When switching over the clamp
2
to a clamping condition, the pressurized oil in the second chamber
22
is discharged to push down the input portion
14
of the clamp rod
5
by the clamp spring
20
. Then the clamp rod
5
goes down along the rotary grooves
27
while rotating in a clockwise direction when seen in plan. Subsequently, it descends straightly along the straight grooves
28
. This enables the clamp rod
5
to switch over to a clamping position (not shown).
As shown by an arrow in
FIG. 2
, when the clamp rod
5
rotates in the clockwise direction when seen in plan, every engaging ball
29
fitted into the rotary groove
27
rolls in a counter-clockwise direction when seen in plan and at the same time the sleeve
35
externally fitted over the respective engaging balls
29
freely rotates in the counter-clockwise direction. This allows almost only rolling friction to act between an inner peripheral surface of the sleeve
35
and every engaging ball
29
, but hardly allows sliding friction to act therebetween. This reduces a resistance which acts from the sleeve
35
to every engaging ball
29
, which results in decreasing a frictional force which acts from every engaging ball
29
to the rotary groove
27
and therefore smoothly rotating the clamp rod
5
with a light force.
Here, the sleeve
35
has an inner diameter set to a value which is about one and half times a value of an outer diameter of the lower slide portion
12
of the clamp rod
5
. Thus in the case of rotating the clamp rod
5
by 90 degrees, the sleeve
35
rotates by about 60 degrees.
When switching over the clamp
2
from the clamping condition to a rotated and retreated condition in
FIG. 1
, the pressurized oil is supplied to the second chamber
22
for unclamping. Then, first, the piston
15
goes up by an upward oil pressure force which acts on an annular sectional area of the piston
15
. Simultaneously, the clamp rod
5
straightly ascends along the straight grooves
28
by an upward oil pressure force which acts on an inner sectional area of the sealing member
16
. Subsequently, the clamp rod
5
ascends along the rotary groove
27
while rotating in the counter-clockwise direction when seen in plan, whereby the clamp rod
5
and the arm
6
switch over to the rotation and retreat position in FIG.
1
.
In this case, as mentioned above, the upward force which acts from the pressurized oil in the second chamber
22
to the piston
15
does not apply to the clamp rod
5
. This prevents an excessive force from acting on the rotary grooves
27
and the engaging balls
29
.
At the above time of rotating and retreating, if the clamp rod
5
rotates in the counter-clockwise direction, every engaging ball
29
and the sleeve
35
rotates in a direction opposite to the direction indicated by the arrow in FIG.
2
.
Further, at the above time of rotating and retreating, as shown in
FIGS. 1 and 4
, the stopper wall
45
has the receiving surface
45
a
fitted with the fitting portion
29
a
of the engaging ball
29
, thereby inhibiting the rotation of the clamp rod
5
. This results in stopping the rotation of the clamp rod
5
with a high accuracy. Moreover, the clamp rod
5
is provided with the stopper wall
45
and therefore offers the following advantage, when compared with a case where the barrel portion
3
c
of the housing
3
is provided with the stopper wall
45
.
The cylindrical hole
4
of the housing
3
need not be provided with a stepped portion for the stopper wall and therefore can be formed straight. This can facilitate the machining of the cylindrical hole
4
and besides can make the clamp spring
20
large and strong.
The first embodiment further offers the following advantages.
The clamp rod
5
is provided with the guide grooves
26
, into which the engaging balls
29
are fitted, respectively. This enables the support cylinder
13
to support the clamp rod
5
peripherally and substantially evenly through the engaging balls
29
. Accordingly, when driven for clamping and for unclamping, the clamp rod
5
can be prevented from inclining. This results in improving the accuracy of placing the push bolt
8
provided in the arm
6
at a clamping position and at an unclamping position.
The partition wall between the adjacent guide grooves
26
,
26
has the minimum thickness (T) set to the value smaller than the groove width (W) of the guide groove
26
. Consequently, many guide grooves can be provided in the clamp rod
5
to result in the possibility of peripherally and substantially evenly supporting the clamp rod
5
and at the same time decreasing the inclination angle (A) of the rotary groove
27
. This can reduce the stroke required for rotating the clamp rod
5
to thereby make the rotary clamp
2
compact.
The clamp rod
5
is provided with the upper slide portion (first slide portion)
11
and the lower slide portion (second slide portion)
12
outside the opposite ends of the piston
15
. Therefore, notwithstanding the existence of a fitting gap of the piston
15
, the two slide portions
11
,
12
axially spaced apart from each other can prevent the inclination of the clamp rod
5
. In consequence, the housing
3
can surely guide the clamp rod
5
with a high accuracy.
The rotary mechanism which comprises the rotary grooves
27
and the engaging balls
29
is provided between the support cylinder
13
which has the above-mentioned guiding strength, and the lower slide portion
12
. Therefore, it can fully endure a rotary torque and increase its service lifetime. In addition, the engaging balls
29
are provided in the support cylinder
13
, thereby enabling portions for installing the engaging balls
29
to serve as a portion for supporting the lower slide portion
12
. Thus it is possible to reduce a height of the housing
3
and make the rotary clamp
2
compact.
Moreover, the lower slide portion
12
has the outer diameter set to the value smaller than that of the outer diameter of the upper slide portion
11
to result in shortening the lead of the rotary groove
27
formed in the lower slide portion
12
. This further reduces the stroke for rotating the clamp rod
5
and as a result can make the rotary clamp
2
more compact. Additionally, the pressurized oil for driving the piston
15
is decreased in supply and discharge amount.
FIG. 5
shows a first modification of the first embodiment and is similar to FIG.
4
. In
FIG. 5
, the partition wall between the adjacent rotary grooves
27
,
27
has the minimum thickness (M) set to a value smaller than that shown in FIG.
4
. The adjacent cutting surfaces
34
,
34
overlap one another at a portion of the minimum thickness (M). Further, in
FIG. 5
, the inclination angle (A) of the rotary groove
27
is set to a value within a smaller range (about 11 degrees to about 15 degrees) than that of FIG.
4
.
FIG. 6
shows a second modification of the first embodiment and is similar to FIG.
4
. In this case, the clamp rod
5
has the lower slide portion
12
provided with four guide grooves
26
. A pair of the adjacent guide grooves
26
,
26
and the corresponding engaging balls
29
are displaced not only peripherally of the clamp rod
5
but also axially thereof. And the partition wall between a pair of the adjacent rotary grooves
27
,
27
has the minimum thickness (M) set to a value smaller than the groove width (W). The partition wall between a pair of the adjacent straight grooves
28
,
28
has a minimum thickness (N) set to a value smaller than the groove width (W). Additionally, the latter minimum thickness (N) is set to a value smaller than that of the former minimum thickness (M). Thus the partition wall between the adjacent guide grooves
26
,
26
has a minimum thickness (T) set to a value smaller than the groove width (W) and the diameter of the engaging ball
29
.
The first embodiment and its modifications can be modified as follows.
It is possible to provide the through holes
31
which rotatably support the engaging balls
29
, in the barrel portion
3
c
of the housing
3
and the like instead of providing them in the support cylinder
13
(lower end wall
3
b
) as exemplified.
The inner peripheral surface of the sleeve
35
may be provided with a U-shaped groove or an arcuate groove instead of the exemplified V-shaped groove
36
. Further, it may be a straight inner peripheral surface. With the straight inner peripheral surface, in order to inhibit the vertical movement of the sleeve
35
with respect to the engaging balls
29
, it is considered to provide a snap ring or the like stopper between the inner wall
13
a
of the support cylinder
13
and the sleeve
35
.
The helically formed rotary groove
27
is inclined at the angle (A) preferably within a range of 10 degrees to 30 degrees and more preferably within a range of 11 degrees to 20 degrees.
FIGS. 7
to
10
show a second embodiment. In the second embodiment, the members similar to the constituent members in the first embodiment are, in principle, designated by the same characters.
In the second embodiment shown in
FIGS. 7
to
10
,
FIG. 7
is a partial sectional view of the rotary clamp
2
when seen in elevation and is similar to FIG.
1
.
FIG. 8
is a sectional view of the rotary mechanism provided in the clamp
2
when seen in plan and is similar to FIG.
2
.
FIG. 9
is an enlarged view of an essential portion in FIG.
7
and corresponds to a sectional view when seen along a line IX—IX in
FIG. 8
in a direction indicated by arrows.
FIG. 10
is an enlarged and developed view of the lower slide portion
12
provided in the clamp rod
5
of the clamp
2
.
The second embodiment is different from the first embodiment on the following points.
The driving means for the clamp rod
5
is formed into a double-acting system. More specifically, pressurized oil for clamping is supplied to and discharged from the first chamber
21
provided upwards of the piston
15
, through a pressurized oil supply and discharge port
17
for clamping. Further, pressurized oil for unclamping is supplied to and discharged from the second chamber
22
provided downwards of the piston
15
, through a pressurized oil supply and discharge port for unclamping (not shown) and the oil passage
18
.
Outside upper and lower opposite sides of another sealing member
15
a
attached to an outer periphery of the piston
15
in fitting relationship, there are formed relatively large fitting gaps between the outer peripheral surface of the piston
15
and the cylindrical hole
4
. This enables the housing
3
to smoothly support the clamp rod
5
with a good accuracy at vertical two portions of the upper slide portion
11
and the lower slide portion
12
.
The lower slide portion
12
has the outer peripheral surface provided with four guide grooves
26
peripherally at substantially the same spacing. Likewise the first embodiment, each of the guide grooves
26
comprises the helical rotary groove
27
and the straight groove
28
which is in upward continuity with the rotary groove
27
. However, the rotary groove
27
has a lower portion opened to an under surface of the clamp rod
5
through a vertically extending groove (designated by no numeral). The engaging ball
29
can be inserted into the guide groove
26
through the opening.
Likewise the first embodiment, as for the adjacent guide grooves
26
,
26
, the partition wall is minimum in thickness between a lower portion of a right rotary groove
27
and an upper portion of a left rotary groove
27
in FIG.
10
. The partition wall has the minimum thickness (M) set to a value smaller than the groove width (W) of the guide groove
26
and the diameter of the engaging ball
29
.
The engaging balls
29
fitted into the respective guide grooves
26
are rotatably supported by the four through holes
31
provided in the upper portion of the inner wall
13
a
of the support cylinder
13
. The sleeve
35
is externally fitted over these four engaging balls
29
rotatably around the axis. The rotary groove
27
is concaved to provide an arcuate recess
37
. Every engaging ball
29
is rollable in the rotary groove
27
at two vertical outside positions of the recess
37
.
A cylindrical spacer
32
is attached between a lower portion of a peripheral wall of the second chamber
22
for unclamping and an upper surface of the support cylinder
13
. The spacer
32
has an upper surface formed with a restricting groove
33
. The restricting groove
33
controls supply amount of the pressurized oil from the oil passage
18
to the second chamber
22
. A though hole or the like is employable instead of the groove
33
.
The support cylinder
13
is pushed and fixed to the housing barrel portion
3
c
by the lock member
39
made of an externally threaded cylinder.
Likewise the first embodiment, the lower slide portion
12
has the outer diameter set to a value smaller than that of the outer diameter of the upper slide portion
11
. This shortens the lead of the helical rotary groove
27
to result in reducing the rotation stroke of the clamp rod
5
.
The respective embodiments and modifications can be further modified as follows.
The clamp rod
5
is preferably provided with three or four guide grooves
26
, but it may be provided with two guide grooves. Further, at least five guide grooves may be provided. And the guide groove
26
may have a groove in the shape of a cam instead of the exemplified helical rotary groove
27
.
It is sufficient if the minimum thickness (T) of the partition wall between the adjacent guide grooves
26
,
26
has a value smaller than the diameter of the engaging ball
29
. In consequence, the minimum thickness (T) can be made to have a value larger than the groove width (W) of the guide groove
26
.
The pressurized fluid which is supplied to and discharged from the first chamber
21
or the second chamber
22
may be other kinds of liquid, and air or the like gas, instead of the exemplified pressurized oil.
Besides, the rotary clamp of the present invention, which comprises the engaging balls
29
and the rotatable sleeve
35
, may be of a single-acting and spring-return type instead of the type that clamps by a spring force or the double-acting type as exemplified.
On performing clamping operation, the clamp rod
5
rotates in the clockwise direction when seen in plan. Instead, on performing the clamping operation, it may rotate in the counter-clockwise direction when seen in plan. Further, it is a matter of course that the rotation angle of the clamp rod
5
may be set to a desired angle, for example, such as 90 degrees, 60 degrees and 45 degrees.
Claims
- 1. A rotary clamp comprising:a housing (3) having a first end wall (3a), a second end wall (3b) and through holes (31); a clamp rod (5) having an outer periphery and being supported by the housing (3) axially movably and rotatably around the axis, the clamp rod (5) being movable for clamping from the first end wall (3a) to the second end wall (3b); guide grooves (26) formed in the outer periphery of the clamp rod (5) peripherally in plural number, each of the guide grooves (26) which comprises a rotary groove (27) and a straight groove (28) provided in continuity with each other from the second end wall (3b) to the first end wall (3a); engaging balls (29) fitted into the guide grooves (26) and rotatably supported by the through holes (31), respectively; and a sleeve (35) externally fitted over the engaging balls (29) rotatably around the axis.
- 2. The rotary clamp as set forth in claim 1, wherein the second end wall (3b) of the housing (3) is provided with a support cylinder (13) which has an inner wall (13a), the clamp rod (5) being inserted into the inner wall (13a) and the through holes (31) being provided in the inner wall (13a).
- 3. The rotary clamp as set forth in claim 1, wherein an annular piston (15) is inserted into the housing (3) axially movably, the clamp rod (5) being inserted into the piston (15), a radial bearing (24) being arranged between these piston (15) and clamp rod (5).
- 4. The rotary clamp as set forth in claim 3, wherein the clamp rod (5) has an input portion (14) and the piston (15) faces the input portion (14) from a side of the first end wall (3a), there being provided between the piston (15) and the first end wall (3a) a first chamber (21) in which a clamp spring (20) is attached, there being provided between the piston (15) and the second end wall (3b) a second chamber (22) to which pressurized fluid for unclamping is supplied.
- 5. The rotary clamp as set forth in claim 3, wherein the clamp rod (5) has an input portion (14) and the piston (15) faces the input portion (14) from a side of the first end wall (3a), there being provided between the piston (15) and the first end wall (3a) a first chamber (21) to which pressurized fluid for clamping is supplied, there being provided between the piston (15) and the second end wall (3b) a second chamber (22) to which pressurized fluid for unclamping is supplied.
- 6. The rotary clamp as set forth in claim 2, wherein an annular piston (15) is inserted into the housing (3) axially movably, the clamp rod (5) being inserted into the piston (15), a radial bearing (24) being arranged between these piston (15) and clamp rod (5).
Priority Claims (1)
Number |
Date |
Country |
Kind |
P 2002-100851 |
Apr 2002 |
JP |
|
US Referenced Citations (7)