Rotary clamp

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.

Number	Name	Date	Kind
5192058	VanDalsem et al.	Mar 1993	A
5820118	Craft	Oct 1998	A
5927700	Yonezawa	Jul 1999	A
5954319	Yonezawa	Sep 1999	A
6113086	Yonezawa	Sep 2000	A
6412763	Noda et al.	Jul 2002	B1
6427992	Noda et al.	Aug 2002	B1

Rotary clamp

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