JP2003089027A - Twist type clamp device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a twist type clamp device disengageable from a hydraulic supply device in a clamped condition while securing strong clamping force. SOLUTION: The twist type clamp device 1 comprises a gas spring 4 for driving retreat and entry of an output rod 3 toward a clamp side, a hydraulic cylinder 5 capable of driving advance of the output rod 3 toward an unclamp side, and a conversion mechanism 6 for converting some force for driving advance and retreat of the output rod 3 to force for driving rotation. The gas spring 4 is provided with a cylinder hole 10, a sleeve member 40 with a piston that is fit externally to the output rod 3 to be rotatable and slidable relative to the output rod 3, and a gas-filled chamber 42 that is defined by the cylinder hole 10 and the sleeve member 40 with the piston and filled with compressed gas 41. When the output rod 3 advances and retreats while twisting, the sleeve member 40 with the piston is configured to only advance and retreat without rotating with respect to a clamp body 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twist type clamp device, and more particularly, to a twist type clamp device provided with a gas spring for driving an output rod to retract toward a clamp side.

[0002]

2. Description of the Related Art Conventionally, various types of clamp devices have been used to fix a workpiece to be machined to a work pallet or the like. Among these clamp devices, there is a twist type clamp device which is provided with a clamp arm that outputs a clamping force to a work and is configured so that the clamp arm does not interfere with the work when the work is attached and detached. In this twist type clamp device,
A clamp arm is attached to the tip of the output rod, and the output rod is retracted to the clamp side while twisting at a specified angle.
Along with the twisting operation of the output rod, the clamp arm also turns a predetermined angle to clamp the work. In this twist type clamp device, a hydraulic cylinder or a spring is generally used as a driving means for driving the output rod forward and backward.

For example, the applicant of the present application has put a twist type clamp device as shown in FIG. 5 into practical use. The twist type clamp device 100 is a double-acting hydraulic cylinder 1 that drives an output rod 102 to move back and forth in a clamp body 101.
It has 03. As shown by the solid line in FIG. 5, in the clamp release state, the clamp arm 104 is the work 1
It is in the retracted position where it does not interfere with 05. When hydraulic pressure is supplied to the clamp side oil chamber 106 of the hydraulic cylinder 103 from this state, the output rod 102 is driven to retreat to the clamp side, but a part of this retreat driving force (clamping force) is converted.
By 08, it is converted into a rotational driving force for rotationally driving the output rod 102, and the output rod retracts while twisting 90 °. At this time, as shown by the chain line in FIG. 5, the clamp arm 104 also turns 90 °, and the lower end of the adjusting bolt 109 abuts the work 105 to clamp the work 105.

In the clamped state, the hydraulic cylinder 10
When hydraulic pressure is supplied to the clamp release side oil chamber 107 of 3, the output rod 102 is driven to advance to the clamp release side.
A part of this advancing drive force (clamp release force) is converted into a rotational drive force by the conversion mechanism, and the output rod 102 is 90 °.
Advances while twisting, and the clamp arm 104 is also 90 °
Turn to return to the retracted position.

On the other hand, the applicant of the present application has proposed and is putting into practical use a non-twist type (direct acting type) clamp device using a gas spring as a clamp means. This gas spring has a gas filling chamber filled with a high-pressure compressed gas (for example, nitrogen gas) of about 7 MPa,
The output rod is constantly urged toward the clamp side by the clamp force generated in the gas filling chamber. In such a clamp device, the clamp device and the external hydraulic supply device can be separated in the clamped state, and the work pallet is conveyed to the machine tool away from the hydraulic supply device while the work is clamped, and the work tool is used by the machine tool. Can be machined. Therefore, it is not necessary to connect the clamp device and the hydraulic pressure supply device with a hose or the like at the time of machining the work, and the degree of freedom of the installation surface of the machine tool, the hydraulic pressure supply device, or the like is increased.

[0006]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In the twist type clamp device including the double-acting hydraulic cylinder,
Since the output rod is driven to the clamp side by the hydraulic cylinder to fix the work, it is necessary to connect the twist type clamp device and the hydraulic pressure supply device when fixing the work to the work pallet and machining it with the machine tool. There is. Therefore, it is necessary to connect the twist type clamp device and the hydraulic pressure supply device with a hose or the like during machining, which hinders the machining work and limits the installation of the machine tool and the hydraulic pressure supply device. A spring can be used as the clamping means instead of the hydraulic cylinder, but a large spring is required to obtain a strong clamping force, and there is a disadvantage that the clamping device becomes large.

On the other hand, the applicant of the present application is very effective to apply the gas spring to the means for driving the output rod to the clamp side in the twist type clamp device as well as the above-mentioned general clamp device. I thought. However, a seal member for sealing the gas filling chamber is installed between the clamp body and the piston part of the output rod, but the clamp when the output rod twists during repeated use. The seal member is deformed in the rotational direction due to the frictional force between the main body and the output rod, so that the seal member is easily worn, the sealability of the seal member is deteriorated, the compressed gas in the gas filling chamber leaks, and the clamp force may be decreased. Can also be considered. An object of the present invention is to configure a twist type clamp device so that it can be separated from a hydraulic pressure supply device in a clamped state, apply a gas spring to a means for driving an output rod to a clamp side, and durability of a seal member of the gas spring. , And so on.

[0008]

A twist type clamp device according to claim 1 has a clamp main body and an output rod attached to the clamp main body so as to be capable of advancing and retreating, and retracts while twisting the output rod at a predetermined angle. In a twist type clamp device that drives and clamps, a gas spring that drives the output rod to retreat to the clamp side, a hydraulic cylinder that can drive the output rod to advance to the unclamped side, and a forward / backward drive force that drives the output rod to advance / retract. And a conversion mechanism for converting a part of the output rod into a rotational driving force for rotationally driving the output rod.

In the unclamped state, the advancing drive force (clamp release force) by the hydraulic cylinder acts on the output rod against the retreat drive force (clamping force) by the gas spring, and the output rod advances to the advance limit position. It is in a state of being When the hydraulic pressure of the hydraulic cylinder is discharged from the unclamped state, the output rod is driven into and out of the clamp side by the clamping force of the gas spring. At this time, a part of the clamping force is converted into a rotational driving force that rotationally drives the output rod by the conversion mechanism, so that the output rod retracts while twisting by a predetermined angle. At this time, the clamp arm attached to the tip portion of the output rod pivots at a predetermined angle from the retracted position where it does not interfere with the work due to the twisting operation of the output rod, and applies a clamping force to the work to fix the work.

Since the gas spring is used as a means for driving the output rod to the clamp side, it is not necessary to connect the twist type clamp device to an external hydraulic pressure supply device in the clamped state. Therefore, for example, after fixing the work to the work pallet, the twist type clamp device and the hydraulic pressure supply device are separated from each other, the work is conveyed to the machine tool separated from the hydraulic pressure supply device, and the work can be processed by the machine tool.

When the hydraulic pressure is supplied from the clamped state to the hydraulic cylinder, the output rod is advanced to the unclamping side by the unclamping force of the hydraulic cylinder against the clamping force of the gas spring. At this time, a part of the unclamping force is converted into a rotational driving force by the conversion mechanism, and the output rod advances while twisting by a predetermined angle in the direction opposite to that in the transition to the clamped state. At this time, the clamp arm also pivots by a predetermined angle and returns to the retracted position in accordance with the twisting operation of the output rod, and the fixing of the work is released.

According to a second aspect of the present invention, in the twist type clamp device of the first aspect, the gas spring is rotationally slid relative to the cylinder hole formed inside the clamp body and the output rod. A sleeve member with a piston that is fitted onto the output rod as much as possible, and a gas filling chamber that is formed by the cylinder hole and the sleeve member with a piston and that is filled with compressed gas are provided.

A seal member is attached to the sleeve member with the piston so that the compressed gas is filled in the gas filling chamber and a clamping force is generated in the gas filling chamber so that the gas pressure does not leak and the clamping force does not decrease. . Since the sleeve member with a piston is rotatable and slidable relative to the output rod, when the output rod performs a forward / backward movement while twisting by a predetermined angle, only the output rod performs a twist operation,
The sleeve member with the piston only moves forward and backward together with the output rod. Therefore, since the sealing member is not deformed in the rotational direction, its sealing performance is not deteriorated, and the compressed gas in the gas filling chamber hardly leaks.

According to a third aspect of the present invention, in the twist type clamp apparatus according to the second aspect, the sleeve member with piston is provided with a gas pressure piston portion slidably mounted in a cylinder hole, and the output rod is provided. Is equipped slidably in the cylinder hole and has a hydraulic piston part that contacts the gas pressure piston part from the opposite side of the gas filling chamber.The sleeve member with piston and the output rod advance and retract integrally with the clamp body. It is characterized by being configured as possible.

When shifting to the clamped state, the clamping force generated in the gas filling chamber of the gas spring acts on the gas pressure piston portion, and this clamping force is transmitted to the hydraulic pressure piston portion contacting the gas pressure piston portion. The output rod is also driven to retract, and the sleeve member with a piston and the output rod retract integrally. When shifting to the unclamped state, the hydraulic pressure acts on the hydraulic piston part to generate a unclamping force, and this unclamping force is transmitted to the gas pressure piston part and the sleeve member with piston is also driven to advance, The attached sleeve member and the output rod integrally advance.

According to a fourth aspect of the present invention, in the twist type clamp device of the third aspect, a thrust bearing is mounted between the gas pressure piston portion and the hydraulic pressure piston portion. Therefore, the forward / backward driving force is transmitted between the sleeve member with the piston and the output rod through the thrust bearing, and relative rotation between them is allowed, so that the output rod moves forward / backward while twisting by a predetermined angle. When performing the operation, the sleeve member with the piston performs only the forward / backward movement integrally with the output rod.

According to a fifth aspect of the present invention, in the twist type clamp device according to any one of the second to fourth aspects, the clamp body is provided with a locking portion for locking the sleeve member with the piston at its advance limit position. It is characterized by being done. Therefore, when shifting to the unclamped state, the sleeve member with a piston is locked by the locking portion and does not advance beyond the advance limit position.

According to a sixth aspect of the present invention, in the twist type clamp device according to any one of the first to fifth aspects, the conversion mechanism includes:
A pair of steel balls held by the clamp body, a rod concentrically fixed to the hydraulic piston portion of the output rod,
It is characterized in that it is provided with a pair of cam grooves formed on the outer peripheral surface portion of the rod and engaged with the pair of steel balls, respectively. Therefore, the rod is also driven forward / backward by the forward / backward driving force acting on the output rod, so that the pair of cam grooves of the rod is moved to one
With the pair of steel balls engaged, the steel balls relatively move along the cam groove, whereby a part of the forward / backward drive force is converted into a rotational drive force, and the output rod performs a twist operation.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described. The twist type clamp device of this embodiment is for fixing a work to be machined to a work pallet. After the work is fixed to the work pallet by the twist type clamp device, the work pallet is conveyed to the machine tool, and the work is machined by the machine tool.

As shown in FIGS. 1 to 3, the twist type clamp device 1 includes a clamp body 2 and the clamp body 2.
Has a output rod 3 mounted so as to be capable of advancing and retracting, and the twist type clamp device 1 drives the output rod 3 by 90 ° twisting while retracting and driving, and twists the output rod 3 by 90 ° in a direction opposite to the clamping direction. While moving forward, the clamp is released. The twist type clamp device 1 includes a gas spring 4 that drives the output rod 3 to retract (clamp side) downward, a hydraulic cylinder 5 that can drive the output rod 3 to move upward (clamp release side), and the output rod 3. And a conversion mechanism 6 for converting a part of the forward / backward driving force to a rotational driving force for rotationally driving the output rod 3.

As shown in FIGS. 1 and 2, the clamp body 2
Is a block having a substantially square shape in a plan view, and the clamp body 2 is fixed to the work pallet 7 with four bolts. The clamp body 2 includes an upper body 2a and a lower body 2b.
Etc. A cylinder hole 10 having a cylindrical hole shape is formed inside the upper body 2a, and a through hole 12 extends upward from the upper end of the cylinder hole 10. This through hole 12
Includes a sleeve member 4 with a piston of the gas spring 4
0 is slidably fitted in the through hole 12 and the seal member 1
3 is installed.

An annular locking portion 14 is formed at the upper end portion of the through hole 12, and this locking portion 14 is for locking the sleeve member 40 with a piston at the advance limit position.
The output rod 3 is inserted through the locking portion 14, and the dust seal 1 is provided on the upper side of the locking portion 14 to prevent chips and the like generated by machining of the work 8 from entering the inside of the clamp body 2.
5 is installed. The lower body 2b is screwed to the lower end portion of the upper body 2a and closes the lower end of the cylinder hole 10. A seal member 18 is mounted between the upper body 2a and the lower body 2b.

The output rod 3 extends upward from the inside of the cylinder hole 10 through the clamp body 2 inside the through hole 12. A clamp arm 20 for outputting the clamping force of the gas spring 4 to the work 8 is fitted onto the upper end portion of the output rod 3 and fixed by a nut 21. A hydraulic piston 25 of the hydraulic cylinder 5 is integrally provided at the lower end of the output rod 3.

The clamp arm 20 is provided with an adjusting bolt 22 capable of adjusting the clamp position of the clamp arm 20 according to the height of the work 8, and the lower end of the adjusting bolt 22 is brought into contact with the work 8. Work 8
To fix. As shown in FIGS. 1 and 2, the clamp arm 20 is in the retracted position where it does not interfere with the work 8 in the unclamped state, and as described later, the output rod 3 is 90 °.
When retracting downward while twisting, the clamp arm 20
Also swivels 90 ° and descends, and as shown in FIG. 3, the clamp arm 20 reaches the work fixing position and fixes the work 8.

The hydraulic cylinder 5 has a hydraulic piston portion 25.
And an oil chamber 26 that generates a clamp release force. The hydraulic piston portion 25 is slidably attached to the lower half of the cylinder hole 10, and the hydraulic piston portion 25 is provided from below the gas piston portion 44 of the gas spring 4 (opposite to the gas filling chamber 42). Abutting. Hydraulic piston part 2
A seal member 27 is mounted between the cylinder 5 and the cylinder hole 10. Below the hydraulic piston portion 25, the hydraulic piston portion 25, the lower half of the cylinder hole 10 and the lower body 2b.
The oil chamber 26 is formed by and the oil pressure is supplied to the oil chamber 26 via the hydraulic port 16 and the oil passage 17 formed in the upper main body 2a. The hydraulic port 16 is a hydraulic pipe (not shown).
A hydraulic pressure can be supplied and discharged by being connected to an external hydraulic pressure supply device (not shown) via.

The gas spring 4 has a cylinder hole 10 and
A sleeve member 40 with a piston fitted onto the output rod 3 so as to be rotatable and slidable relative to the output rod 3, and a gas filling formed with a cylinder hole 10 and a sleeve member 40 with a piston and filled with a compressed gas 41. And a chamber 42. The sleeve member 40 with a piston is formed by integrally forming a sleeve portion 43 and a gas pressure piston portion 44 below the sleeve portion 43. Sleeve part 43
The upper half of the above is slidably fitted in the through hole 12, and the gas pressure piston portion 44 is slidably attached to the upper half of the cylinder hole 10. A seal member 45 that seals the gas filling chamber 42 is attached to the gas pressure piston portion 44. The hydraulic piston portion 25 is in contact with the lower surface of the gas pressure piston portion 44 so that the sleeve member with piston 40 and the output rod 3 can be integrally advanced and retracted.

A thrust bearing 46 is mounted between the gas pressure piston portion 44 and the hydraulic pressure piston portion 25. The forward / backward drive force is transmitted between the sleeve member with piston 40 and the output rod 3 via the thrust bearing 46, and relative rotation between them is allowed, and the forward / backward movement is performed while the output rod 3 is twisted. When performing, the sleeve member with piston 40 does not rotate with respect to the clamp body 2 but moves integrally with the output rod 3 only in the vertical direction.

The gas filling chamber 42 is filled with a high pressure (for example, 7 MPa) compressed gas 41 such as nitrogen gas through a gas filling valve 47 provided in the upper main body 2a. A strong clamping force is always generated in this gas filling chamber 42, and this clamping force is applied to the sleeve member 40 with a piston.
Is transmitted to the output rod 3 via the gas pressure piston portion 44 and the hydraulic pressure piston portion 25. That is, the output rod 3 is always urged downward by this clamping force.

The conversion mechanism 6 is formed on a pair of steel balls 30 held by the clamp body 2, a rod 31 concentrically fixed to the hydraulic piston portion 25, and an outer peripheral surface portion of the rod 31. And a pair of cam grooves 32 engaged with a pair of steel balls 30, respectively. At the lower end of the output rod 3,
A rod fitting hole 23 extending from the lower end of the output rod 3 to an intermediate portion in the vertical direction is formed concentrically with the hydraulic piston portion 25, and the upper end portion of the rod 31 is fitted in the rod fitting hole 23. The rod 31 is fixed to the output rod 3 by two screw members 33, and a seal member 34 is mounted between the rod 31 and the rod fitting hole 23. An insertion hole 19 extending downward from the upper end surface of the lower body 2b is formed in the axial center portion of the lower body 2b. When the output rod 3 retracts, the lower half of the rod 31 is inserted into the insertion hole 19.
Is inserted into.

Above the lower body 2b, an annular holding member 36 fixed to the lower body 2b by a plurality of bolts 35,
An annular holding plate 3 attached to the upper end of the holding member 36
7 are provided, and the pair of steel balls 30 are restricted from moving in the horizontal plane and in the vertical direction by the holding member 36 and the holding plate 37. The pair of cam grooves 32 are formed symmetrically with respect to the axial center on the outer peripheral surface portion of the rod 31, and each cam groove 32 is formed by the rod 3
1 and a vertical groove 32a extending upward from the lower end of the vertical groove 1.
The twist groove 32b extends upward along the outer circumference of the rod 31 in the range of 90 ° in the circumferential direction from the upper end of a, and the vertical groove 32c extends upward from the upper end of the twist groove 32b.

As shown in FIG. 1, in the unclamped state, each steel ball 30 is engaged with the corresponding vertical groove 32a. In this state, when the output rod 3 retracts due to the clamping force, the rod 31 also retracts into the insertion hole 19, but at this time, the steel ball 30 moves along the vertical groove 32a.
It will move upward relative to 1. Steel ball 3
When 0 reaches the upper end of the vertical groove 32a, the steel ball 30 moves relative to the rod 31 along the twist groove 32b this time, but the steel ball 30 is held by the clamp body 2. Therefore, a part of the clamping force is converted into the rotational driving force of the rod 31, the rod 31 rotates 90 °, and the output rod 3 retracts and twists 90 ° at the same time.

When the steel ball 30 reaches the upper end of the twist groove 32b, the steel ball 30 moves relatively upward with respect to the rod 31 along the vertical groove 32c, so that the output rod 3 retracts downward. . Similarly, when shifting from the clamped state to the unclamped state, part of the unclamping force is converted into the rotational driving force of the rod 31 by the conversion mechanism 6, and the output rod 3 twists 90 ° and moves upward. You will make a foray.

Next, the operation of the twist type clamp device 1 will be described. As shown in FIG. 1, in the unclamped state, the hydraulic pressure is supplied to the oil chamber 26 from the external hydraulic pressure supply device via the hydraulic port 16 and the oil passage 17 to generate the unclamping force. The output rod 3 and the sleeve member with piston 40 are driven upward by the force against the clamping force of the gas spring 4. At this time, the sleeve member 40 with the piston is locked at the advance limit position by the annular locking portion 14.

When shifting from the unclamped state of FIG. 1 to the clamped state of FIG. 3, the oil pressure in the oil chamber 26 is changed to the oil passage 17,
The oil is discharged to an external hydraulic pressure supply device via the hydraulic pressure port 16. When the hydraulic pressure is discharged from the oil chamber 31, the clamp releasing force does not act on the output rod 3 and only the clamping force acts on the piston sleeve member 40 and the output rod 3. Therefore, the sleeve member 40 with the piston and the output rod 3 are integrally driven downward by the clamping force.

At this time, part of the clamping force is converted by the conversion mechanism 6.
Is converted into a rotational driving force, and the output rod 3 retracts while twisting 90 °. However, since relative rotation is allowed between the sleeve member 40 with a piston and the output rod 3, only the output rod 3 performs a twisting operation, and the sleeve member with a piston 40 is clamped by the clamp body 2.
With respect to the output rod 3, only the retreat operation is performed without rotating. Therefore, the seal member 45 that seals the gas filling chamber 42 is not deformed in the rotation direction, and the sealing property of the seal member 45 does not deteriorate, so that the compressed gas 41 hardly leaks.

When the output rod 3 retracts while twisting 90 °, the clamp arm 20 also pivots 90 ° from the retracted position and descends to reach the workpiece fixing position, and the lower end of the adjusting bolt 22 of the clamp arm 20 causes the workpiece 8 to move. The work 8 is fixed to the work pallet 7 by contacting with the work 8 and outputting the clamping force to the work 8. After shifting to the clamped state, the hydraulic port 16 and the hydraulic pressure supply device are disconnected, the work pallet 7 is conveyed to the machine tool, and the work 8 is machined by the machine tool.

When shifting from the clamped state to the unclamped state, the hydraulic port 16 is connected to the hydraulic pressure supply device to supply the hydraulic pressure to the oil chamber 26 and generate the unclamping force in the oil chamber 26. This clamp release force causes the output rod 3
The sleeve member 40 with the piston and the piston-attached sleeve member 40 are integrally advanced and driven upward. However, as in the transition to the clamped state, a part of the unclamping force is converted into the rotational driving force by the conversion mechanism 6, and the output rod 3 Moves forward while twisting 90 ° in the opposite direction to the time of shifting to the clamped state. At this time, the sleeve member with piston 40 is attached to the clamp body 2
With respect to the output rod 3, only the advancing operation is performed without rotating. When the output rod 3 advances upward while twisting by 90 °, the clamp arm 20 also rises from the work fixing position and turns 90 ° to reach the retracted position, and the fixation of the work 8 is released.

According to the above twist type clamp device 1, the following effects can be obtained. 1) Twist type clamp device 1 in the clamped state
The work pallet 7 by disconnecting the
Since the workpiece can be conveyed to the machine tool and the work 8 can be machined, it is not necessary to connect the twist-type clamp device 1 and the hydraulic pressure supply device with a hose or the like during the machining of the work, and the machine tool or the hydraulic pressure supply device. The degree of freedom of the installation surface such as. 2) Unlike the case where a clamping force is generated by a spring, the work 8 can be strongly fixed even with a relatively small gas spring 4, and the twist type clamping device 1 can be made compact.

3) When the output rod 3 twists 90 ° and moves forward and backward, only the output rod 3 twists, and the sleeve member with piston 40 does not rotate with respect to the clamp body 2 and outputs. Since only the advancing / retreating operation is performed integrally with the rod 3, the seal member 45 is not deformed in the rotational direction, and thus the seal member 4 is not repeatedly deformed.
5 does not deteriorate the sealing performance of the compressed gas 4 in the gas filling chamber 42.
1 does not leak and the clamping force does not decrease.

4) The clamp body 2 has a locking portion 1 for locking the sleeve member 40 with a piston at the advance limit position.
4 is provided, the sleeve member with piston 40 is locked by the locking portion 14 when shifting to the unclamped state, so that the sleeve member with piston 40 advances beyond the advance limit position and jumps out from the clamp body 2. Never.

Next, a description will be given of a modified form in which various modifications are made to the above embodiment. As shown in FIG. 4, in the twist type clamp device 1A, the sleeve member 40A with a piston of the gas spring 4A may be arranged so as to protrude from the clamp body 2A. Hereinafter, the same structure as that of the above-described embodiment is denoted by the same reference numeral, and the description thereof will be appropriately omitted.

The sleeve member 40A with a piston is fitted onto the output rod 3 so as to be rotatable and slidable, and the cylinder hole 10A.
Through the through hole 12A to project upward. In the inner part of the tip of the sleeve member with piston 40A,
A dust seal 51 for preventing chips and the like from entering the output rod 3 is mounted, and a step portion 50 is formed at the center of the sleeve member with piston 40A in the vertical direction. Inside the clamp body 2A, the cylinder hole 10
At the upper end of A, a locking portion 14A that locks the sleeve member with piston 40A at the advance limit position is formed. In the unclamped state, the step portion 50 engages with the locking portion 14A, and the piston-equipped sleeve member 40A is locked at the advance limit position. The other actions and effects are the same as those in the above-mentioned embodiment, and the description thereof will be omitted.

The conversion mechanism is not limited to the structure of the above-described embodiment, and various structures such as a ball screw mechanism can be adopted. In addition, it goes without saying that the present invention can be applied to those which can be easily conceived by those skilled in the art based on the above-described embodiments without departing from the spirit of the present invention.

[0044]

According to the invention of claim 1, since the twist type clamp device is provided with the gas spring for driving the output rod to retreat to the clamp side, in the clamped state, the twist type clamp device is supplied with an external hydraulic pressure. Since it can be separated from the device, it is not necessary to connect the twist type clamp device and the hydraulic pressure supply device with a hose etc. during machining of the work, and the degree of freedom of the installation surface of the machine tool or the hydraulic pressure supply device is expanded. . Further, the work can be strongly fixed even with a relatively small gas spring, and the twist type clamp device can be made compact.

According to the second aspect of the present invention, when the output rod moves forward and backward while twisting at a predetermined angle, only the output rod performs the twisting operation, and the sleeve member with the piston moves forward and backward integrally with the output rod. Since the seal member mounted on the sleeve member with piston does not deform in the rotation direction, the sealability of the seal member does not deteriorate even after repeated use, and compressed gas in the gas filling chamber leaks. The clamping force does not decrease. In addition, the same effect as that of the first aspect can be obtained.

According to the third aspect of the invention, when shifting to the clamped state, the clamping force by the gas spring is transmitted from the gas pressure piston portion to the hydraulic pressure piston portion, the output rod is also driven to retract, and the clamp is released. When shifting to the state, the clamp release force by the hydraulic cylinder is transmitted from the hydraulic piston part to the gas pressure piston part, and the sleeve member with piston is also driven forward. The member and the output rod can be integrally moved forward and backward with respect to the clamp body. In addition, the same effect as that of the second aspect can be obtained.

According to the fourth aspect of the present invention, since the thrust bearing is mounted between the gas pressure piston portion and the hydraulic pressure piston portion, the thrust bearing advances and retreats between the sleeve member with the piston and the output rod. Since the drive force is transmitted and relative rotation between the two is allowed, when the output rod twists and moves forward and backward, the sleeve member with piston is not rotated with respect to the clamp body, It can be driven integrally with the output rod only in the forward / backward direction. In addition, the same effect as the third aspect can be obtained.

According to the fifth aspect of the present invention, the clamp body is provided with the engaging portion for engaging the piston-equipped sleeve member at the advance limit position thereof. Since the sleeve member is locked by the locking portion, the sleeve member with the piston does not advance beyond the advance limit position and jump out from the clamp body.
In addition, the same effect as that of any one of claims 2 to 4 can be obtained.

According to the sixth aspect of the invention, the conversion mechanism includes a pair of steel balls held by the clamp body, a rod fixed to the output rod, and a pair of steel balls formed on the outer peripheral surface of the rod. Since the steel balls are provided with a pair of cam grooves engaged with each other, when the output rod is driven forward and backward, the rod is also driven forward and backward by the forward and backward driving force, and the pair of cam grooves of the rod is moved forward and backward.
By moving the steel balls relative to each other along the cam groove with the pair of steel balls engaged, part of the forward / backward drive force can be converted into the rotational drive force for rotationally driving the output rod. Can be twisted by a predetermined angle. In addition, the same effect as that of any one of claims 1 to 5 can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a twist type clamp device (unclamped state) according to an embodiment of the present invention.

FIG. 2 is a plan view of a twist type clamp device.

FIG. 3 is a vertical cross-sectional view of a twist type clamp device (clamping state).

FIG. 4 is a view corresponding to FIG. 1 showing a modified form.

FIG. 5 is a vertical cross-sectional view of a conventional twist type clamp device.

[Explanation of symbols]

1,1A twist type clamp device 2,2A Clamp body 3 output rod 4,4A gas spring 5 hydraulic cylinder 6 conversion mechanism 10,10A cylinder hole 14,14A Locking part 25 Hydraulic piston part 30 steel balls 31 rod 32 cam groove 40,40A Sleeve member with piston 41 Compressed gas 42 Gas filling chamber 44 Gas pressure piston 46 Thrust bearing

Claims (6)

[Claims] 1. A twist type clamp device having a clamp body and an output rod mounted on the clamp body so as to be capable of advancing and retreating, wherein the output rod is clamped by retracting and driving while twisting the output rod by a predetermined angle. A gas spring that drives the clamp side back and forth, a hydraulic cylinder that can drive the output rod forward toward the clamp release side, and a part of the forward-backward drive force that drives the output rod forward and backward is converted to rotational drive force that rotationally drives the output rod. A twist type clamp device characterized by comprising: 2. The gas spring, a cylinder hole formed inside the clamp body, and a sleeve member with a piston fitted on the output rod so as to be rotatable and slidable relative to the output rod. A gas filling chamber filled with compressed gas, which is formed by the cylinder hole and the sleeve member with a piston, is provided.
The twist type clamp device described in. 3. The sleeve member with piston is provided with a gas pressure piston portion slidably mounted in a cylinder hole, and the output rod is slidably mounted in the cylinder hole. 3. A hydraulic piston portion, which is in contact with the gas filling chamber from the opposite side, is provided, and the sleeve member with the piston and the output rod are integrally movable with respect to the clamp body. Twist type clamp device. 4. The twist type clamp device according to claim 3, wherein a thrust bearing is mounted between the gas pressure piston portion and the hydraulic pressure piston portion. 5. The twist type according to any one of claims 2 to 4, wherein the clamp body is provided with a locking portion for locking the piston-equipped sleeve member at its advance limit position. Clamp device. 6. The conversion mechanism is formed on a pair of steel balls held by a clamp body, a rod concentrically fixed to a hydraulic piston portion of the output rod, and an outer peripheral surface portion of the rod. The twist type clamp device according to any one of claims 1 to 5, further comprising a pair of cam grooves in which the pair of steel balls are engaged with each other.