WO2011070891A1

WO2011070891A1 - Clamping device

Info

Publication number: WO2011070891A1
Application number: PCT/JP2010/070120
Authority: WO
Inventors: 隆司二宮; 義則松下
Original assignee: パスカルエンジニアリング株式会社
Priority date: 2009-12-11
Filing date: 2010-11-11
Publication date: 2011-06-16
Also published as: JP2011121144A; TW201130597A

Abstract

Disclosed is a clamping device (1) which drives a clamp rod (10) in the direction of a clamp body (30) so as to anchor an object (W). The clamp rod (10) comprises four annular engagement sections (14) in the axial direction. The clamp body (30) comprises four collet members (34) which are annularly disposed so as to form part of a rod insertion hole (31), are capable of radially expanding/contracting through parallel movement, each having four annular pressing sections (64) in the axial direction; a hydraulic cylinder (33) for driving the four collet members (34) and the clamp rod (10) in the insertion direction; and a first guide mechanism (35) which, at the time of driving, guides the four collet members (34) in such a way that the four collet members (34) radially contract and the multiple annular pressing sections (64) engage with the four annular engagement sections (14) from above, and at the time of clamp release, guides the four collet members (34) in such a way that the four collet members (34) radially expand and the four annular pressing sections (64) are separated from the four annular engagement sections (14).

Description

Clamping device

The present invention relates to a clamp device, and in particular, the clamp rod is configured to be detachable from the clamp body, and is fixed by retreating to the clamp body side in a state where the clamp rod is inserted into the hole of the workpiece. The present invention relates to a clamping device.

Conventionally, among the workpieces of various shapes and structures used for machining, for example, the upper end surface and outer peripheral surface of a workpiece having a stepped hole composed of a large diameter hole and a small diameter hole, such as a bush-shaped member and a sleeve-shaped member. In the case of machining, a bolt type clamping device is widely adopted.
For example, as shown in FIG. 18, the bolt-type clamping device CL includes a thick plate-like work pallet 200 for attaching a work and a plurality of bolts 201. A plurality of bolt holes 202 are formed in the work pallet 200 at appropriate intervals in the vertical and horizontal directions, and a plurality of workpieces W are respectively arranged at the positions of the plurality of bolt holes 202. A large diameter hole 203 and a small diameter hole 204 of each work W The bolt 201 is inserted into the stepped hole 205 and screwed into the bolt hole 202, the bolt head 201a is accommodated in the large diameter hole 203, and the stepped portion of the stepped hole 205 is pressed by the bolt head 201a. In this way, the work W is fixed to the work pallet 200. In this clamped state, the upper end surface and outer peripheral surface of the workpiece W can be machined.

Patent Document 1 discloses a plurality of types of work positioning and fixing jigs that clamp and fix the end of a work using bolts. For example, a workpiece positioning and fixing jig shown in FIG. 9 of Document 1 includes a base member placed on the upper surface of a table, an adjustment member screwed into a screw hole of the base member, an adjustment member, and a workpiece. A clamp member disposed on the upper surface; and a bolt member having a bolt head locked in a T-groove of the table, the base member, the adjustment member, and a bolt member fixing the clamp member to the table.

Patent Document 2 discloses a clamp device with a ball lock mechanism in which a pull bolt (clamp rod) that is substantially the same as a pull stud is screwed on the lower surface side of a workpiece and the pull bolt is detachably fixed. Has been.

The clamp device includes a housing, a hydraulic cylinder having an annular piston provided inside the housing, a sleeve that is mounted in a through shape so that the annular piston is penetrated, and is driven to be released from the clamp by the hydraulic cylinder, and a sleeve A plurality of balls (steel balls) mounted in the plurality of ball holding holes so as to be movable in the radial direction, and a ring-shaped operation member having a tapered surface capable of guiding these balls to the axial center side in the radial direction. When clamping the workpiece, with the pull bolt inserted into the sleeve from above, the hydraulic cylinder is clamp driven to lower the sleeve, and a plurality of balls are moved to the radial axial center via the tapered surface of the ring-shaped operating member. It is moved and engaged with the large-diameter portion of the pull bolt, and is pulled downward and fixed through a plurality of balls.

Patent Document 3 discloses a pallet clamp device with a collet chuck that is configured so that a pull stud is screwed onto a lower surface side of a workpiece and the pull stud is detachably fixed. For example, the collet chuck is formed with claw portions at the tip of each of the four collets, the four collets are moved forward and backward by a hydraulic cylinder, the four collets are swung, and the four claw portions are expanded and contracted. Switch to the state. When clamping, pull studs are introduced into the four claw portions in the diameter-expanded state, then the four claw portions are reduced in diameter, and the pull studs are clamped by the four claw portions.

JP 2001-293626 A JP-A-9-285925 JP 2005-81480 A

In the bolt type clamping device, it takes a lot of labor to fasten a plurality of bolts for clamping a work, and it is difficult to speed up the bolt fastening work performed by a nut runner or the like. Even though it is desirable to machine with multiple workpieces pressed under a load condition equal to the load condition applied under actual usage conditions, multiple bolts that secure multiple workpieces are fastened with a constant torque Even if this occurs, there will be variations in the pressing force that clamps the workpiece due to wear on the screw part of the bolt, friction due to the adhesion of fine chips and lubrication, etc. There is also a problem that the clamping force cannot be accurately managed or controlled.

In the work positioning and fixing jig of Patent Document 1, since the work is fixed via a bolt, there is a problem similar to that of the bolt type clamping device. Moreover, since at least a part of the upper surface of the workpiece is pressed by the clamp fitting of the workpiece positioning and fixing device, it cannot be applied to a workpiece in which the entire upper surface of the workpiece is machined.

In the clamp device with the ball lock mechanism of Patent Document 2, the contact portion between the ball and the pull bolt is not a surface contact but a line contact (correctly an arc contact), and therefore the contact surface pressure is extremely high. When the clamping force is strengthened, an indentation is generated in the pull bolt or the ball holding hole every time the clamping is performed, and it is difficult to improve the durability. In addition, in the case of the ball lock mechanism, it is difficult to reinforce the clamping force as in the case of a bolt type clamping device because a plurality of balls arranged in a ring cannot be arranged in a plurality of stages.
Also in the clamping device of Patent Document 3, since the plurality of collets clamp the head of the pull stud, there is a problem similar to that of the clamping device with a ball lock mechanism of Patent Document 2.

An object of the present invention is a clamp device in which a clamp rod for fixing an object to be clamped is detachable, the clamp device capable of strengthening the clamp force, accurately managing or controlling the clamp force, and enhancing durability. Is to provide.

The clamp device of the present invention includes a clamp body having a rod insertion hole into which a clamp rod can be partially inserted from above, and a vertical clamp rod that can be attached to and detached from the rod insertion hole, and the clamp rod is attached to the clamp body. In the clamping device that drives to retreat toward and fixes the object to be clamped, the clamp rod has a plurality of annular engagement portions formed at a plurality of positions in the axial direction thereof, and the clamp main body includes the rod A plurality of collet members arranged annularly so as to form a part of the insertion hole and capable of being reduced / expanded by parallel movement, and a plurality of annular pressing portions formed at a plurality of locations in the axial direction A plurality of collet members, a clamp actuator for driving the plurality of collet members and the clamp rod in the retracting direction, and the clamp When the clamp is driven by the actuator, the plurality of collet members are reduced in diameter so that the plurality of annular pressing portions are engaged with the plurality of annular engagement portions from above, and the plurality of collet members are guided when the clamp is released. A first guide mechanism that guides the plurality of collet members so that the plurality of collet members expand in diameter and the plurality of annular pressing portions are separated from the plurality of annular engagement portions when the collet member moves upward. It is characterized by that.

In the clamping device of the present invention, a plurality of collet members arranged in an annular shape can be reduced in diameter / expanded by parallel movement, and a plurality of annular pressing portions are provided at a plurality of locations in the axial direction of the plurality of collet members. When the clamp is driven by the clamp actuator, the plurality of annular pressing portions are engaged with the plurality of annular engagement portions formed at a plurality of locations in the axial direction of the clamp rod. Therefore, the contact area between the plurality of annular pressing portions and the plurality of annular engaging portions can be remarkably increased, and the clamping force is enhanced while the annular pressing portion of the clamp rod and the annular engaging portion of the collet member are provided. The acting surface pressure can be kept low.

According to the clamping device of the present invention, a plurality of annular pressing portions are provided at a plurality of locations in the axial direction of a plurality of collets arranged in an annular shape, and a plurality of annular engagement portions are provided at a plurality of locations in the axial direction of the clamp rod. Since the plurality of collet members are reduced in diameter by parallel movement via the first guide mechanism during clamp driving, the plurality of annular pressing portions are configured to engage with the plurality of annular engagement portions from above. The clamping force can be remarkably strengthened, and the area of the contact portion between the annular pressing portion and the annular engagement portion can be greatly increased to maintain the surface pressure low, thereby enhancing the durability of the clamping device. The clamping force can be accurately managed or controlled via the driving force of the clamping actuator, and a stable clamping force can be generated.

When releasing the clamp, the clamp rod is pulled out from the rod insertion hole in order to expand the diameter of the plurality of collet members by parallel movement through the first guide mechanism and separate the plurality of annular pressing portions from the plurality of annular engagement portions. be able to. Therefore, it is possible to clamp the clamp rod with the clamp rod inserted through the hole of the workpiece.

In addition to the configuration of the present invention, the following various configurations may be employed.
(A) Each annular pressing portion has a downward annular pressing surface that is orthogonal or substantially orthogonal to the axis of the clamp rod, and each annular engagement portion is in surface contact with the annular pressing surface and pressed. Having an upward annular engagement surface.

According to this configuration, each annular pressing portion has a downward annular pressing surface that is orthogonal or substantially orthogonal to the axis of the clamp rod, and each annular engaging portion is pressed in surface contact with the annular pressing surface. Therefore, the transmission efficiency of transmitting the driving force of the clamp drive by the clamp actuator to the clamp rod can be increased, and the clamp device can be miniaturized.

(B) The clamp actuator includes a fluid pressure cylinder, and the fluid pressure cylinder includes an annular piston member and an annular fluid pressure working chamber for applying fluid pressure to the upper surface side of the annular piston member. In this case, a first return mechanism for returning the plurality of collet members and the annular piston member of the fluid pressure cylinder to the clamp release position is provided.

According to this configuration, when releasing the clamp, the annular piston member of the fluid pressure cylinder can be returned to the clamp release position by the first return mechanism.

(C) The fluid pressure cylinder has an auxiliary annular piston that is slidably fitted to the annular piston member and receives the fluid pressure in the annular fluid pressure working chamber on the lower surface side, and the body case of the clamp body Has a top wall portion that forms a part of the rod insertion hole, and the first guide mechanism is a taper for reducing diameter formed on the outer peripheral surface and the inner peripheral surface of the upper end side portion of the plurality of collet members, respectively. And a diameter-reducing taper surface, and a diameter-reducing taper formed on the upper end portion of the auxiliary annular piston and for reducing the diameter of the plurality of collet members by guiding the diameter-reducing taper surface when the hydraulic cylinder is clamped. A guide surface, and a diameter-increasing taper guide surface that is formed at a lower portion of the upper wall portion of the main body case and guides the diameter-expanding taper surface when releasing the clamp of the fluid pressure cylinder to expand the plurality of collet members. Is provided.

According to this configuration, the first guide mechanism includes a diameter-reducing taper surface and a diameter-enlarging taper surface formed at the upper end portions of the plurality of collet members, and a diameter-reducing taper formed at the upper end portion of the auxiliary annular piston. Since it has a guide surface and a taper guide surface for diameter expansion formed on the upper wall portion of the main body case, it is possible to reduce the diameter of the plurality of collet members in conjunction with the descending of the plurality of collet members during clamp driving. When the clamp is released, the plurality of collet members can be increased in diameter in conjunction with the rise of the plurality of collet members.

(D) The body case of the clamp body has an upper wall part that forms a part of the rod insertion hole, and an outer peripheral wall part on the outer peripheral side of the plurality of collet members, and the first guide mechanism includes a plurality of The diameter-decreasing taper surface and the diameter-expanding taper surface respectively formed on the outer peripheral surface and the inner peripheral surface of the upper end side portion of the collet member, and formed on the inner peripheral portion of the outer peripheral wall portion and at the time of clamp driving of the fluid pressure cylinder A diameter-reducing taper guide surface that guides the diameter-reducing taper surface to reduce the diameter of the plurality of collet members, and the diameter-expansion is formed when the fluid pressure cylinder is released from the clamp. And a taper guide surface for expanding the diameter of the plurality of collet members.

According to this configuration, since the tapered guide surface for diameter reduction is formed on the outer peripheral wall portion of the main body case, the same effect as the above (c) can be obtained without using the auxiliary annular piston.

(E) The plurality of collet members have a flange portion formed at a lower end portion so that an annular piston member of the fluid pressure cylinder faces from above, and is formed on an inner peripheral portion of the flange portion of the plurality of collet members. A tapered driven surface having a larger diameter as it goes downward, an annular engaging member having a tapered engaging surface that engages with the tapered driven surface, and a compression spring that elastically biases the annular engaging member upward. A second guide mechanism is provided.

According to this configuration, the tapered driven surface formed on the flange portion of the plurality of collet members, the annular engaging member having the tapered engaging surface engaged with the tapered driven surface, and the annular engaging member elastically upward. Since the second guide mechanism including the urging compression spring is provided, the second guide mechanism can assist the operation of expanding the diameter of the plurality of collet members by the first guide mechanism when releasing the clamp.

(F) The plurality of collet members have a flange portion formed at a lower end portion so that the annular piston members of the hydraulic cylinder face each other from above, and are formed on the upper surface of the flange portion and become smaller in diameter toward the upper side. A third guide mechanism including a tapered driven surface and a tapered pressing surface formed on the annular piston member so as to abut on the tapered driven surface is provided.

According to this configuration, the tapered driven surface formed on the upper surface of the flange portion of the plurality of collet members and having a smaller diameter toward the upper side, and the tapered pressing surface formed on the annular piston member so as to contact the tapered driven surface. Since the provided third guide mechanism is provided, the third guide mechanism can strongly assist the operation of reducing the diameter of the plurality of collet members by the first guide mechanism during clamp driving.

(G) The plurality of collet members have a flange portion formed at a lower end portion so that the annular piston member of the fluid pressure cylinder faces from above, and the upper surface portion of the flange portion and the annular piston member are A rotation restricting mechanism is provided which allows a reduction in diameter / expansion of the plurality of collet members and restricts rotation of the plurality of collet members around the vertical axis.

According to this configuration, the rotation restricting mechanism that allows the diameter reduction / expansion of the plurality of collet members and restricts the rotation around the vertical axis between the flange portions of the plurality of collet members and the annular piston member is provided. Further, the stability of the operation of reducing / expanding the diameter of the plurality of collet members can be improved. For example, when a plurality of collet members are in a diameter-expanded state, if there is no gap between adjacent collet members, the operation of reducing the diameter may become unstable.

It is a longitudinal cross-sectional view of the clamp apparatus (clamp releasing state) which concerns on Example 1 of this invention. It is a front view of a clamp rod. It is a perspective view of four collet members. It is a longitudinal cross-sectional view of four collet members. It is the top view which looked at the collet member from the upper part. It is a longitudinal cross-sectional view of a clamp apparatus (clamp driving middle state). It is a longitudinal cross-sectional view of a clamp apparatus (clamp state). It is a longitudinal cross-sectional view of the clamp apparatus which concerns on Example 2. FIG. It is a longitudinal cross-sectional view of the clamp apparatus which concerns on Example 3. FIG. It is a longitudinal cross-sectional view of the clamp apparatus which concerns on Example 4. FIG. It is a longitudinal cross-sectional view of the clamp apparatus which concerns on Example 5. FIG. It is a longitudinal cross-sectional view of the clamp apparatus concerning Example 6. 10 is a perspective view of four collet members according to Embodiment 7. FIG. It is a top view of four collet members. It is a longitudinal cross-sectional view of four collet members. It is a bottom view of four collet members. FIG. 10 is a longitudinal sectional view of a diameter reducing / expanding actuator according to an eighth embodiment. It is a longitudinal cross-sectional view of the bolt type clamp apparatus which concerns on a prior art.

Hereinafter, the best mode for carrying out the present invention will be described based on examples.
In the following embodiments, the vertical direction in FIG. 1 will be described as the vertical direction in the usage state of the clamp device.

Hereinafter, a clamp device 1 according to the first embodiment will be described with reference to FIGS.
As shown in FIGS. 1 to 6, the clamp device 1 basically includes a clamp rod 10 and a clamp body 30 that clamps the clamp rod 10 downward. This clamping device 1 is used for use in a state of being incorporated in a work pallet 2 that is normally prepared by the user. A plurality of clamping devices 1 are arranged at predetermined intervals on the work pallet 2, and a workpiece W (clamp object) is fixed on the mounting surface 2 a of the work pallet 2 by each of the plurality of clamping devices 1. Provided for processing. However, the clamp apparatus 1 can also be used in a form in which the work pallet 2 is omitted and the upper surface of the clamp body 30 is the mounting surface.

The illustrated workpiece W is an example, and the workpiece W has a recessed portion 3a opened on the upper end surface and a through hole 3b penetrating from the lower end central portion to the lower surface of the recessed portion 3a. In a state where the cylindrical surface is formed and the workpiece W is clamped to the workpiece pallet 2 by the clamping device 1, the upper end surface and / or the outer peripheral surface of the workpiece W is machined.

In the work pallet 2, a vertical through hole 4 and four bolt holes 5 around the through hole 4 are formed so as to penetrate from the placement surface 2a to the internal accommodation space 2b. The clamp body 30 is housed in the housing space 2 b and is fixed to the work pallet 2 by four bolts 6 inserted through the bolt holes 5.

The clamp rod 10 is formed at an upper end portion and can be accommodated in the recess 3a, a rod portion 12 having a smaller diameter than the head portion 11 and extending downward from the lower end of the head portion 11 by a predetermined length, and a rod portion 12 is formed integrally with an engagement rod portion 13 formed in a predetermined range portion (a predetermined range upward from the lower end surface) on the lower end side extending downward from the lower end. The head portion 11 has a cylindrical shape, the rod portion 12 and the engaging rod portion 13 have a common vertical axis A, and the horizontal cross section of the rod portion 12 and the engaging rod portion 13 is circular.

The head portion 11 is formed to have a larger diameter than the through hole 3b, and the rod portion 12 and the engagement rod portion 13 can be inserted into the through

holes

3b and 4, and the lower half portion of the rod portion 12 and the engagement rod portion 13 is detachably inserted into the rod insertion hole 31 of the clamp body 30. Therefore, in the clamped state, when the clamp rod 10 is pulled and driven toward the clamp body 30 (clamp drive), the lower end surface of the head portion 11 presses the bottom surface of the recess 3a downward. At this time, the upper end surface of the head portion 11 is positioned below the upper end surface of the workpiece W.

As shown in FIGS. 1 to 5, the engagement rod portion 13 is formed with four annular engagement portions 14 at four positions equally spaced in the axial direction. Each annular engagement portion 14 has a tapered surface 14a that increases in diameter toward the top, an outer peripheral surface 14b that is formed in a cylindrical shape (parallel to the axis A of the clamp rod 10) from the upper end of the tapered surface 14a, It has an upward annular engagement surface 14c formed so as to be orthogonal or substantially orthogonal to the axis A of the clamp rod 10 at a position at the upper end of the surface 14b and at a position on the smaller diameter side from the upper end. A cylindrical surface 14d extending upward from the inner periphery of the engaging surface 14c and having a diameter equal to the minimum diameter of the tapered surface 14a is also formed. The inclination angle of the tapered surface 14a with respect to the vertical direction is about 20 to 25 degrees. The radius from the axis A of the clamp rod 10 to the outer peripheral surface 14 b is set equal to the radius of the rod portion 12. A tapered surface 14e similar to the tapered surface 14a is formed at the lower end of the rod portion 12.

The clamp rod 10 has been described with an example of a structure in which the work W is pressed by the lower end surface of the head portion 11. However, the male screw portion is formed on the head portion 11 and the male screw portion is formed on the work W. The clamp rod 10 comprised so that it might fasten to the female thread part which did it may be sufficient.

The clamp body 30 of the clamp device 1 includes a body case 32, a hydraulic cylinder 33 (corresponding to a clamp actuator), four collet members 34, a first guide mechanism 35, a first return mechanism 36, and a second A return mechanism 37 and a rotation restricting mechanism 38 are provided.

Next, the main body case 32 will be described.
The main body case 32 is screwed into an upper wall member 40 that forms the upper end portion thereof, a cylindrical cylinder member 41, a closing member 42 that closes the lower end portion of the cylinder member 41, and a screw hole in the lower end portion of the cylinder member 41. And a ring member 43 for fixing the closing member 42. The upper wall member 40 has a cylindrical wall portion 44 extending downward from the lower end of the central portion thereof, and an upper rod insertion hole that is an upper portion of the rod insertion hole 31 formed in the upper wall member 40 so as to be continuous below the through hole 4. 31a, a plurality of bolt holes 46, and the like. The upper wall member 40 is fixed to the cylinder member 41 by screwing the plurality of bolts 47 inserted into the plurality of bolt holes 46 into the plurality of bolt holes 48 of the cylinder member 41.

On the outer peripheral portion of the lower end portion of the cylindrical wall portion 44, a diameter-increasing taper guide surface 45 that increases in diameter toward the upper side for expanding the diameter of the four collet members 34 when the clamp is released is formed. An annular dust seal 49 capable of sliding contact with the outer periphery of the clamp rod 10 is mounted in the vicinity of the upper end of the upper rod insertion hole 31a.

A first cylinder hole 51 that guides the auxiliary annular piston member 55 so as to be movable up and down is formed inside the upper portion of the cylinder member 41 (about 2/5 of the total length). The second cylinder hole 52 is a second cylinder hole 52 having a larger diameter than the first cylinder hole 51 and in which the piston portion 53a of the annular piston member 53 is oil-tightly slidably mounted. Is formed. The work pallet 2 and the cylinder member 41 are formed with

oil passages

54 a and 54 b that can supply and discharge hydraulic pressure to and from the annular hydraulic working chamber 54. The upper wall member 40 is fitted with a seal member 7a, the cylinder member 41 is fitted with seal members 7b to 7f, the annular piston member 53 is fitted with a seal member 8a, and the auxiliary annular piston member 55 is sealed. A member 8b is mounted.

Next, the hydraulic cylinder 33 will be described.
The hydraulic cylinder 33 (corresponding to a fluid pressure cylinder) drives the four collet members 34 and the clamp rod 10 in the retracting direction (downward), and is provided in the main body case 32. The hydraulic cylinder 33 is disposed above the annular piston member 53, an annular hydraulic working chamber 54 (corresponding to an annular fluid pressure working chamber) that applies hydraulic pressure to the upper surface side of the annular piston member 53, and the annular piston member 53. And an auxiliary annular piston member 55 that receives the hydraulic pressure of the annular hydraulic working chamber 54 on the lower surface side. The annular hydraulic working chamber 54 is formed by the cylinder member 41 of the main body case 30, the annular piston member 53, and the auxiliary annular piston member 55. The annular hydraulic working chamber 54 is supplied with hydraulic pressure from an external hydraulic supply source via

oil passages

54a and 54b.

The annular piston member 53 has a piston portion 53 a and a cylindrical portion 53 b extending upward from the piston portion 53 a, and most of the four collet members 34 are accommodated inside the annular piston member 53. The auxiliary annular piston member 55 includes a piston portion 55a, a cylindrical portion 55b extending upward from the piston portion 55a, and an annular portion 55c formed at the upper end of the cylindrical portion 55b and facing the cylindrical portion 53b from above. The piston portion 55a and the cylindrical portion 55b are externally fitted to the cylindrical portion 53b so as to be oil-tightly slidable. On the inner peripheral portion of the annular portion 55c, a taper guide surface 56 for reducing the diameter that increases in diameter upward is formed. The outer diameter of the piston portion 55a is smaller than the outer diameter of the piston portion 53a, and the pressure receiving area of the annular piston member 53 is set to be about two to three times the pressure receiving area of the auxiliary annular piston member 55.

Next, the four collet members 34 will be described.
The four collet members 34 are reduced in diameter by parallel movement when the clamp is driven and engaged with the clamp rod 10, transmit the clamping force to the clamp rod 10, and are expanded from the clamp rod 10 by parallel movement when the clamp is released. Thus, the clamp rod 10 can be pulled upward.

The four collet members 34 are annularly arranged in the main body case 32 to form a collet inner rod insertion hole 31b which is a part of the rod insertion hole 31, and the diameter reduction position engages with the clamp rod 10 by parallel movement. And an enlarged diameter position separated from the clamp rod 10 can be switched. The four collet members 34 have a structure in which an annular collet body integrally formed in an annular shape is divided into four equal parts in the circumferential direction.

The four collet members 34 include a tapered wall portion 57 formed on the upper end side portion and having a larger diameter upward, a cylindrical portion 58 extending downward from the lower end of the tapered wall portion 57, and the cylindrical portion 58. The flange portion 59 is formed integrally with the lower end portion, and the flange portion 59 is formed so that the annular piston member 53 of the hydraulic cylinder 33 faces from above.

Four annular pressing portions 64 are provided at four positions equally spaced in the axial direction of the cylindrical portions 58 of the four collet members 34, and are in surface contact with the four annular engaging portions 14 of the clamp rod 10 from above. Four annular pressing portions 64 that can be pressed are formed. Each annular pressing portion 64 has a tapered surface 64a having a larger diameter as it goes downward, an outer peripheral surface 64b formed in parallel with the axis A of the clamp rod 10 so as to extend downward from the lower end of the tapered surface 64a, and an outer peripheral surface 64b. And a downward annular pressing surface 64c formed so as to be orthogonal or substantially orthogonal to the axis A of the clamp rod 10 at the lower end position (position on the smaller diameter side from the lower end). A cylindrical surface 64d extending downward from the inner periphery of the pressing surface 64c and having a diameter equal to the minimum diameter of the tapered surface 64a is also formed. A tapered surface 64e similar to the tapered surface 64a is also formed at the lower end portion of the cylindrical portion 58.

On the outer periphery of the tapered wall portion 57 (upper end portion) of the four collet members 34, there is a diameter-reducing taper surface 66 that increases in diameter toward the upper side, and is formed on the diameter-reducing taper guide surface 56 of the auxiliary annular piston member 55. A slidable reduced diameter taper surface 66 and a cylindrical surface 67 extending upward from the upper end of the reduced diameter taper surface 66 are formed. On the inner periphery of the taper wall portion 57 (upper end portion), a diameter-expanding taper surface 68 that can slide on the diameter-expansion taper guide surface 45 of the upper wall portion 44 is formed.

Next, the first guide mechanism 35 will be described.
The first guide mechanism 35 translates the four collet members 34 to the reduced diameter state when the clamp is driven, and translates the four collet members 34 to the enlarged diameter state when releasing the clamp. The first guide mechanism 35 is configured so that the four collet members 34 are reduced in diameter and the four annular pressing portions 64 are engaged with the four annular engaging portions 14 from above when clamp driving is performed by the hydraulic cylinder 33. The four collet members 34 are guided, and when the four collet members 34 move upward when the clamp is released, the four collet members 34 are expanded in diameter, and the four annular pressing portions 64 are separated from the four annular engaging portions 14. In this manner, the four collet members 34 are guided.

In the present embodiment, the first guide mechanism 35 has the diameter-reducing tapered surfaces 66 and the diameter-enlarging tapered surfaces 68 formed on the four collet members 34 and the diameter-reducing diameter of the annular portion 55 c of the auxiliary annular piston member 55. The taper guide surface 56 for use and the taper guide surface 45 for expanding the diameter of the cylindrical wall portion 44 of the upper wall member 40 are configured. In the cross-sectional view shown in FIG. 1, the four

surfaces

66, 68, 56, 45 are parallel.

Next, the first return mechanism 36 will be described.
The first return mechanism 36 is configured to return the four collet members 34 and the annular piston member 53 of the hydraulic cylinder 33 upward to the clamp release position when releasing the clamp, and is configured as follows. On the inner side of the piston portion 53 a of the annular piston member 53, a first accommodation hole 60 that accommodates the flange portions 59 of the four collet members 34 and a second accommodation hole 61 that continues to the lower end of the first accommodation hole 60 are formed. Has been. The second accommodation hole 61 is slightly larger in diameter than the first accommodation hole 60, and an annular annular plate 71 having a center hole 70 is attached to the second accommodation hole 61. The annular plate 71 is received by the step portion 61 a at the upper end of the second accommodation hole 61, and allows the flange portions 59 of the four collet members 34 to move in the radial direction.

In the second cylinder hole 52, a spring accommodating chamber 72 into which pressurized air is introduced from an external pressurized air supply source via

air passages

72a and 72b is formed between the annular plate 71 and the closing member 42. A first compression coil spring 73 and a second compression coil spring 74 surrounding the outside of the first compression coil spring 73 are mounted in the spring accommodating chamber 72, and the annular plate 71 is attached by the first and second compression coil springs 73, 74. The annular piston member 53 and the four collet members 34 are elastically biased upward (clamp release direction).

Next, the second return mechanism structure 37 will be described.
The 2nd return mechanism structure 37 returns the clamp rod 10 to a clamp release position at the time of clamp release, and is comprised as follows. A boss portion 42a that protrudes upward is formed in the central portion of the closing member 42, and a through hole 75 is formed in the upper wall of the boss portion 42a. A rod support member 76 for returning the clamp rod 10 is provided. The upper half portion of the rod support member 76 is formed in a thick tubular shape, the lower half portion is formed in a thin tubular shape, and a spring is formed in the lower half portion. A receiving hole 77 is formed.

The upper end surface of the rod support member 76 is in contact with the lower end of the clamp rod 10, and the lower portion of the rod support member 76 is inserted into the through hole 75. A flange 76a that is locked by the upper wall of the boss portion 42a is formed at the lower end portion of the rod support member 76. The rod support member 76 and the clamp rod 10 are placed in the internal space of the boss portion 42a and the spring receiving hole 77. A compression coil spring 78 that elastically biases upward is mounted. The lower end of the compression coil spring 78 is supported by a spring receiver 79 with a hole, and the spring receiver 79 is supported by a stop ring 80.

Next, the rotation restricting mechanism 38 will be described.
The rotation restricting mechanism 38 is provided on the upper surface portion of the flange portion 59 of the four collet members 34 and the annular piston member 53. The rotation restricting mechanism 38 allows the reduction / expansion of the four collet members 34 and restricts the rotation of the four collet members 34 around the axis thereof, and is configured as follows. In the central portion of the upper surface of the flange portion 59 of each collet member 34 in the circumferential direction, a radially restricting groove 81 is formed, and in the horizontal wall portion of the piston portion 53a of the annular piston member 53, four restricting grooves 81 are formed. Two hemispherical recesses 82 opposed to each other are formed, and two steel balls 83 are rotatably mounted in each set of hemispherical recesses 82, and the two steel balls 83 are rotatably engaged with the corresponding regulation grooves 81. Has been.

Next, the air blow mechanism will be described.
When the clamp rod 10 is pulled out in the clamp release state, pressurized air is supplied from the

air passages

72a and 72b, the spring accommodating chamber 72, the center hole 70 of the annular plate 71, the rod insertion hole 31b in the collet, and the upper rod insertion. By jetting pressurized air in the order of the hole 31a and the through-hole 4, the inside thereof is cleaned and foreign matter such as chips is prevented from adhering. When releasing the clamp by releasing the hydraulic pressure of the hydraulic cylinder 33, air blow is performed in the same manner as described above to prevent chips from entering.

Next, the operation and effect of the clamping device 1 described above will be described.
The clamp device 1 operates in a clamp release state shown in FIG. 1, a clamp driving halfway state in which the four collet members 34 shown in FIG. 6 are reduced in diameter, and a clamp state shown in FIG.

As shown in FIG. 1, in a state where no hydraulic pressure (correctly pressurized oil) is supplied to the annular hydraulic working chamber 54 of the hydraulic cylinder 33, the annular piston member 53, the auxiliary annular piston member 55, and the four collet members 34. Is held at the upper limit position as shown. In this state, the four collet members 34 maintain the expanded diameter state, and the inner diameter of the collet inner rod insertion hole 31 b inside the four collet members 34 is larger than the outer diameter of the clamp rod 10. Can be attached to and detached from the clamp body 30. When the workpiece W is set in this state, the clamp rod 10 is pulled upward, the workpiece W is set, and then the clamp rod 10 is inserted into the through

holes

3b and 4 and the rod insertion hole 31 as shown in FIG. Put it in a state.

In the state of FIG. 1, the diameter-reducing taper surfaces 66 of the four collet members 34 are close to and parallel to the diameter-reducing taper guide surface 56, and the diameter-expansion taper surface 68 is parallel to the diameter-expansion taper guide surface 45. Is close to. The clamp rod 10 is held at the upper limit position as shown in the figure by the second return mechanism 37, and the distance from the lower end of the head portion 11 of the clamp rod 10 to the bottom surface of the recess 3 a is the flange portion of the rod support member 76. It is smaller than the distance between 76a and the spring support 79.

Next, as shown in FIG. 6, when the hydraulic pressure is supplied to the annular hydraulic working chamber 54 of the hydraulic cylinder 33, the auxiliary annular piston member 55 is initially urged upward by the hydraulic pressure, so that the upper limit position is maintained and the annular position is maintained. Since the piston members 53 are lowered, the four collet members 34 have their diameter-reducing taper surfaces 66 guided by the diameter-reducing taper guide surfaces 56 and moved parallel to the diameter-reducing side, so that they are integrated with the annular piston member 53. Descend. At this time, the diameters of the four collet members 34 are reduced by parallel movement in a state where the axial centers thereof are substantially coincident with the axial center A of the clamp rod 10.

As a result, as shown in the drawing, the four annular pressing portions 64 of the four collet members 34 engage with the four annular engaging portions 14 of the clamp rod 10 from above, and each annular pressing surface 64c corresponds to the corresponding annular engagement. The surface is in surface contact with the surface 14c. In addition, the inclination angle with respect to the vertical direction of the taper surfaces 14a and 64a is set to be substantially equal to the inclination angle of the taper surfaces 66 and 68. In the middle of clamping in FIG. 6, the head portion 11 of the clamp rod 10 has not yet pressed the workpiece W.

As described above, when the four collet members 34 are in a reduced diameter state, as shown in FIG. 7, the annular piston member 53, the auxiliary annular piston member 55, and the four collet members 34 are integrally clamped downward. The head portion 11 is in a clamped state in which the workpiece W is strongly pressed. When releasing the clamp, when the hydraulic pressure in the annular hydraulic working chamber 54 is released, the annular piston member 53, the auxiliary annular piston member 55, and the four collet members 34 are moved by the return force of the first and

second return mechanisms

36, 37. The clamp is integrally driven upward and the state shown in FIG. 6 is obtained.

When the annular piston member 53, the auxiliary annular piston member 55, and the four collet members 34 are further raised, the diameter-expanding taper surfaces 68 of the four collet members 34 are guided by the diameter-increasing taper guide surfaces 45. While the member 34 moves upward, the diameter of the member 34 is expanded by parallel movement and the state shown in FIG. 1 is obtained. At this time, the four collet members 34 are translated in a state where the axial centers thereof are substantially coincident with the axial center A of the clamp rod 10.

According to this clamping device 1, the following effects can be obtained.
When the clamp is driven, the four collet members 34 are reduced in diameter by translation through the first guide mechanism 35, and the four annular pressing portions 64 are engaged with the four annular engaging portions 14 from above. Therefore, it is possible to increase the area of the contact portion between the annular pressing portion 64 and the annular engagement portion 14 while keeping the clamping force remarkably strong, so that the surface pressure can be kept low, and the durability of the clamping device 1 can be improved. In addition, the magnitude of the clamping force can be appropriately set via the hydraulic pressure supplied to the hydraulic cylinder 33, and the clamping force can be accurately managed or controlled, so that a stable clamping force can be generated. For example, the workpiece W can be machined while being pressed under the same load condition as in the use state.

Each annular pressing portion 64 has a downward annular pressing surface 64c that is orthogonal or substantially orthogonal to the axis A of the clamp rod 10, and each annular engagement portion 14 is in surface contact with the annular pressing surface 64c and pressed. Therefore, the transmission efficiency of transmitting the driving force of the clamp drive by the hydraulic cylinder 33 to the clamp rod 10 can be increased, and the clamp device 1 can be downsized.

When releasing the clamp, the diameter of the four collet members 34 is expanded by parallel movement through the first guide mechanism 35 and the four annular pressing portions 64 are separated from the four annular engaging portions 14. It can be pulled out from the rod insertion hole 31. Therefore, it is also possible to clamp the clamp rod 10 inserted into the through-hole 3b of the workpiece W.

The first guide mechanism 35 includes a diameter-reducing taper surface 66 and a diameter-expansion taper surface 68 formed on the four collet members 34, a diameter-reduction taper guide surface 56 formed on the auxiliary annular piston member 55, and the main body case 32. The diameter of the four collet members 34 can be reduced in conjunction with the lowering of the four collet members 34 when the clamp is driven. The four collet members 34 can be increased in diameter in conjunction with the rise of the four collet members 34. Therefore, there is no need to provide a dedicated actuator for reducing or expanding the diameter of the four collet members 34 other than the hydraulic cylinder 33, which is advantageous.

As shown in FIG. 3, there is a gap 34a between the collet members 34 when the diameter is expanded, and the gap 34a is minute when the diameter is reduced. A rotation restricting mechanism 38 is provided, and four gaps 34a between the collet members 34 are provided in order to allow the diameter reduction / expansion of the four collet members 34 and to restrict the rotation of the four collet members 34 around the vertical axis. Is maintained evenly, and the stability of the diameter reducing operation and the diameter expanding operation is not impaired.

Next, a clamp device 1A according to the second embodiment will be described with reference to FIG.
This clamping device 1A employs a double-acting hydraulic cylinder 33A in place of the hydraulic cylinder 33. The same main components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different components are described. In FIG. 8, the left half of the figure shows the clamp release state, and the right half of the figure shows the clamp driving state.

The hydraulic cylinder 33A has an annular hydraulic working chamber 54 on the upper side of the annular piston member 53A and a hydraulic working chamber 72A on the lower side of the annular piston member 53A, and an annular plate that supports the flange portions 59 of the four collet members 34. 71A is prevented from coming off by a stop ring 86, a seal member 87 for oil-tight sealing is mounted on the outer peripheral portion of the annular plate 71A, and the rod support member 76 is slidable in an oil-tight manner in the center hole 70A of the annular plate 71A. The seal member 88 is inserted into the inner periphery of the center hole 70A. The first return mechanism 36A includes a hydraulic working chamber 72A, an annular plate 71A, and the like.

The blocking member 42A is formed with a thick wall, and a seal member 89 for sealing between the rod support member 76 and the upper wall portion is mounted.

Oil paths

72c and 72d for supplying hydraulic pressure from an external hydraulic supply source are provided in the hydraulic working chamber 72A. The operation and effect of the clamp device 1A are substantially the same as those of the clamp device 1 of the first embodiment. However, since the annular piston member 53A and the four collet members 34 are driven to return upward by the hydraulic pressure supplied to the hydraulic operation chamber 72A, the return force can be enhanced. Note that an air working chamber may be provided instead of the hydraulic working chamber 72A, and pressurized air may be supplied thereto.
When pressurized air is supplied to the lower end portion of the spring accommodating hole 90 as an air blow mechanism, the pressurized air flows into the four collet members 34 through the passages 76 a in the rod support member 76.

Next, a clamp device 1B of Example 3 will be described with reference to FIG.
Since this clamping device 1B is obtained by changing a part of the clamping device 1A of the second embodiment, the same major components as those of the second embodiment are denoted by the same reference numerals, and the description thereof is omitted. Omitted, only different components will be described. In FIG. 9, the left half of the figure shows the clamp release state, and the right half of the figure shows the clamp driving state.

A compression coil spring 91 is attached to the annular hydraulic working chamber 54B of the hydraulic cylinder 33A. The compression coil spring 91 elastically biases the annular piston member 53B downward, and elastically biases the auxiliary annular piston member 55B upward. A part of the clamp driving force is generated by the hydraulic pressure of the annular hydraulic working chamber 54B, and a part of the clamp driving force is generated by the compression coil spring 91. In the clamping device 1B, even when the hydraulic pressure in the annular hydraulic working chamber 54B is lowered due to oil leakage or the like, it is possible to maintain the clamp driving force corresponding to the elastic force of the compression coil spring 91.

Next, a clamp device 1C according to the fourth embodiment will be described with reference to FIG.
In the clamping device 1C, the auxiliary annular piston member 55 of the hydraulic cylinder 33 of the clamping device 1 is omitted, and a reduced diameter taper guide surface 56C instead of the reduced diameter taper guide surface 56 formed on the auxiliary annular piston member 55 is provided. The outer peripheral wall portion 41a of the main body case 32C is formed. The same main components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different components are described. In FIG. 10, the left half of the figure shows the clamp release state, and the right half of the figure shows the clamp driving state.

The outer peripheral wall 41a of the cylinder member 41C located on the outer peripheral side of the four collet members 34C is expanded to a region occupied by the auxiliary annular piston member 55, and a taper guide surface 56C for reducing diameter is provided on the outer peripheral wall 41a. Is formed. Therefore, the first guide mechanism 35C includes the diameter-reducing taper surface 66 and the diameter-enlarging taper surface 68 formed on the outer peripheral surface and the inner peripheral surface of the tapered wall portion 57C of the four collet members 34C, and the above-mentioned reduced diameter. The taper guide surface 56C for diameter and the taper guide surface 45 for diameter expansion formed in the upper wall part 44 of the upper wall member 40 are comprised. The outer diameters of the tapered wall portions 57C of the four collet members 34C are reduced, and an outer peripheral cylindrical surface 67C that continues to the upper end of the diameter-expanding tapered surface 68 is formed. Since the auxiliary annular piston member 55 is omitted, the structure of the clamping device 1C is simplified.

Next, a clamp device 1D of Example 5 will be described with reference to FIG.
Since this clamping device 1D is obtained by changing a part of the clamping device 1C of the fourth embodiment, the same major components as those of the fourth embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Omitted, only different components will be described. In FIG. 11, the left half of the figure shows the clamp release state, and the right half of the figure shows the clamp driving state.

The clamp device 1D is provided with a second guide mechanism 94 that assists the diameter expansion of the four collet members 34D when the clamp is released. The second guide mechanism 94 includes a tapered driven surface 95 that is formed on the inner peripheral portion of the flange portion 59D of the four collet members 34D and that increases in diameter downward, and a tapered engagement surface that engages with the tapered driven surface 95. An annular engagement member 97 having 96 and a compression spring 98 for elastically urging the annular engagement member 97 upward are provided. An annular annular plate 71D for receiving the lower end portion of the flange portion 59D of the collet member 34D is fixed inside the annular piston member 53.
Since the second guide mechanism 94 is provided, when the clamp is released, the first guide mechanism 35C effectively assists the diameter expansion operation of expanding the four collet members 34D, and the diameter expansion operation below the four collet members 34D. Can be stabilized.

Next, a clamp device 1E according to the sixth embodiment will be described with reference to FIG.
Since this clamping device 1E is obtained by changing a part of the clamping device 1D of the fifth embodiment, the same major components as those of the fifth embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Omitted, only different components will be described. In FIG. 12, the left half of the figure shows the clamp release state, and the right half of the figure shows the clamp driving state.

In the clamp device 1E, the third guide mechanism 100 that assists the diameter-reducing operation of the flange portions 59E below the four collet members 34E is provided when the clamp is driven.
The third guide mechanism 100 includes a tapered driven surface 101 formed on the upper surface of the flange portion 59E and having a smaller diameter toward the upper side, and a tapered pressing surface 102 formed on the annular piston member 53E so as to contact the tapered driven surface 101. It has. At the time of clamp driving, not only a force driving downward from the taper pressing surface 102 of the annular piston member 53E to the taper driven surface 101 of the flange portion 59E but also a force pressing toward the axis A of the clamp rod 10 acts. It is possible to assist the diameter reduction operation of the flange portion 59E of the two collet members 34E and stabilize the diameter reduction operation. A rotation restricting mechanism 38E similar to the rotation restricting mechanism 38 of the clamp device 1 is also provided.

Next, the four collet members 34F and the rotation restricting mechanism according to the seventh embodiment will be described.
As shown in FIGS. 13 to 16, a lower rectangular recess 103 capable of accommodating the lower half of the plurality of steel balls 82 is formed on the upper surface of the flange portion 59F of each collet member 34F. Instead of the two recesses 82, an upper rectangular recess (not shown) that can accommodate the upper half of the plurality of steel balls 82 is formed, and the lower rectangular recess 103 and the upper rectangle in each of the four collet members 34F. A plurality of steel balls 82 are accommodated in the recess.

Further, an upper rectangular recess 104 capable of accommodating the upper half portions of the plurality of steel balls 82 is formed on the lower surface of the flange portion 59F of each collet member 34F, and the lower half portions of the plurality of steel balls 82 are formed on the annular plate. A lower rectangular recess (not shown) that can be accommodated is formed, and a plurality of steel balls 82 are accommodated in the upper rectangular recess 104 and the lower rectangular recess in each of the four collet members 34F. With the above configuration, rotation around the axis of the clamp rod is restricted while enabling smooth reduction / expansion of the four collet members 34F.

Next, a diameter reduction / expansion actuator according to Example 8 will be described with reference to FIGS. For example, in the clamping device 1C according to the fourth embodiment, the cylindrical portion 53b of the annular piston member 53 is omitted, and the reduced diameter / expansion actuator 110 shown in FIG. (This corresponds to the first guide mechanism) is mounted so as to move up and down integrally with the four collet members 34C. In the clamp device 1C, the

tapered surfaces

66 and 68 and the tapered

guide surfaces

56C and 45 can be omitted, but they may be used together without being omitted.

The diameter-reduction / expansion actuator 110 includes a leaf spring member 111 for diameter expansion having a C-shaped horizontal section, and an elastic synthetic resin annular tube 112 provided on the outer peripheral side of the leaf spring member 111. An annular tube 112 capable of reducing the diameter of the leaf spring member 111 for diameter expansion by filling with hydraulic pressure, an annular low friction member 113 fixed to the outer peripheral surface of the annular tube 112, and an oil chamber 112a in the annular tube 112 are externally provided. Hydraulic pressure supply means (not shown) capable of supplying and discharging hydraulic pressure from the hydraulic pressure supply source. The diameter-reduction / diameter-expansion actuator 110 is mounted on the cylindrical portions 58 of the four collet members 34 </ b> C in an externally fitted state, and the diameter-expanding leaf spring member 111 is in contact with the cylindrical portions 58.

The middle step of the inner peripheral surface of the annular tube 112 is fixed to the leaf spring member 111, and the middle step of the outer peripheral surface of the annular tube 112 is fixed to the annular low friction member 113. In addition, a plurality of elongated holes 111a are formed in the leaf spring member 111 so as to correspond to the respective collet members 34C, and bolts 111b with heads inserted from the outside into the respective elongated holes 111a are plate springs. It is fixed to the member 111 by screwing. Therefore, the diameter of the four collet members 34 </ b> C can be expanded by the diameter expansion operation of the leaf spring member 111.

When driving the clamp, the hydraulic cylinder 33 is supplied with hydraulic pressure, and the hydraulic pressure is supplied to the oil chamber 112a in the annular tube 112 by the hydraulic supply means, thereby lowering the diameter expansion leaf spring member 111 and the four collet members 34C. Then, the diameter is reduced by parallel movement to obtain a clamped state. When releasing the clamp and releasing the hydraulic pressure of the hydraulic cylinder 33 and the annular tube 112, the four collet members 34C are lifted by the elastic force of the diameter-expanding leaf spring member 111 and expanded in parallel to release the clamp. It becomes a state. Since this diameter-reduction / diameter-expansion actuator 110 is externally fitted to the cylindrical portions 58 of the four collet members 34C and drives the cylindrical portions 58 toward the reduced diameter side, the diameter-reducing operation can be stabilized. . Similarly, since the cylindrical part 58 is driven to the diameter expansion side by the leaf spring member 111, the diameter expansion operation can be stabilized.

An example in which the first to seventh embodiments are partially changed will be described.
1) Instead of the four collet members 34 divided into four equal parts in the circumferential direction, 3 to 6 collet members divided into 3 to 6 equal parts in the circumferential direction may be adopted.

2] The number of the annular engaging portions 14 and the number of the annular pressing portions 64 are not limited to four, and a plurality of appropriate annular engaging portions 14 and the annular pressing portions 64 may be provided. The shape of the annular engagement portion 14 is not limited to that shown in the figure, and may be any annular engagement portion 14 having an annular engagement surface 14c that can withstand an applied load. Similarly, the shape of the annular pressing portion 64 is also illustrated. However, the present invention is not limited thereto, and any annular engagement portion 64 having an annular engagement surface 64c that can withstand an applied load may be used.

3] As the clamping actuator, an air cylinder may be employed instead of a hydraulic cylinder, and an electric motor, an electric linear actuator, or the like may be employed.
4] Depending on the workpiece W, clamp rods having different lengths are employed as the clamp rod 10. Various structures can be adopted as a structure for transmitting a load from the clamp rod 10 to the workpiece W.
5] In addition, those skilled in the art can implement the present invention in a form in which various modifications are added without departing from the spirit of the present invention, and the present invention includes them.

W Workpiece (Clamp object)
1, 1A to 1E Clamp device 10 Clamp rod 14 Annular engagement portion 14c Engagement surface 30 Clamp body 32

Body case

33, 33A

Hydraulic cylinders

34, 34C to 34F Collet member 35

First guide mechanism

36, 36A First return mechanism 37

Second return mechanism

38, 38E Rotation restricting mechanism 40 Upper wall member 41a Outer wall portion 44 Tube wall portion 45 Diameter increasing taper guide surfaces 53, 53A, 53B, 53E

Annular piston members

54, 54B Annular hydraulic working

chambers

55, 55B Auxiliary

annular piston members

56, 56C Tapered guide surface 57 for diameter reduction Tapered wall (upper end portion)
59, 59D to 59F Flange portion 64 annular pressing portion 64c pressing surface 66 taper surface for diameter reduction 68 taper surface for diameter expansion 94 second guide mechanism 95 taper driven surface 97 annular engagement member 98 compression spring 100 third guide mechanism 101 taper Driven surface 102 taper pressing surface 110 actuator for diameter reduction / expansion

Claims

A clamp body having a rod insertion hole into which the clamp rod can be partially inserted from above, and a vertical clamp rod which can be attached to and detached from the rod insertion hole, and drives the clamp rod to retreat toward the clamp body. In the clamping device for fixing the clamping object,
The clamp rod has a plurality of annular engaging portions formed at a plurality of positions in the axial direction thereof,
The clamp body is
A plurality of collet members arranged in an annular shape so as to form a part of the rod insertion hole and capable of being reduced / expanded by parallel movement, and formed at a plurality of locations in the axial direction of the collet members A plurality of collet members having a portion;
A clamp actuator for driving the plurality of collet members and the clamp rod in the retracting direction;
When the clamp is driven by the clamp actuator, the plurality of collet members are reduced in diameter, and the plurality of annular pressing portions are guided to the plurality of annular engagement portions from above, and the plurality of collet members are guided and clamped. A first guide mechanism that guides the plurality of collet members so that when the plurality of collet members move upward at the time of release, the plurality of collet members expand in diameter and the plurality of annular pressing portions are separated from the plurality of annular engagement portions. And a clamping device.
Each of the annular pressing portions has a downward annular pressing surface that is orthogonal or substantially orthogonal to the axis of the clamp rod, and each of the annular engaging portions is pressed upward in surface contact with the annular pressing surface. The clamping device according to claim 1, further comprising an annular engagement surface.
The clamping actuator includes a fluid pressure cylinder. The fluid pressure cylinder includes an annular piston member and an annular fluid pressure working chamber for applying fluid pressure to the upper surface side of the annular piston member. The clamp device according to claim 2, further comprising a first return mechanism for returning the collet member and the annular piston member of the fluid pressure cylinder to a clamp release position.
The fluid pressure cylinder has an auxiliary annular piston that is slidably fitted to the annular piston member and receives the fluid pressure of the annular fluid pressure working chamber on the lower surface side,
The body case of the clamp body has an upper wall part that forms a part of the rod insertion hole,
The first guide mechanism is formed on a diameter-reducing taper surface and a diameter-enlarging taper surface formed on an outer peripheral surface and an inner peripheral surface of upper end side portions of a plurality of collet members, and an upper end portion of the auxiliary annular piston. And a diameter-reducing taper guide surface that guides the diameter-reducing taper surface when the fluid pressure cylinder is clamped to reduce the diameter of the plurality of collet members, and is formed at a lower portion of the upper wall portion of the main body case. 4. The clamping device according to claim 3, further comprising a diameter-increasing taper guide surface that guides the diameter-increasing taper surface when releasing the clamp of the cylinder and expands the plurality of collet members.
The body case of the clamp body has an upper wall part that forms a part of the rod insertion hole, and an outer peripheral wall part on the outer peripheral side of a plurality of collet members,
The first guide mechanism is formed on the outer peripheral surface and the inner peripheral surface of the upper end side portion of the plurality of collet members, and on the inner peripheral portion of the outer peripheral wall portion, and on the inner peripheral portion of the outer peripheral wall portion. And a diameter-reducing taper guide surface for guiding the diameter-reducing taper surface when the fluid pressure cylinder is clamped to reduce the diameter of the plurality of collet members, and a fluid formed on the lower portion of the upper wall portion of the body case. The clamping device according to claim 3, further comprising a diameter-increasing taper guide surface that guides the diameter-expanding taper surface when the pressure cylinder is released to expand the diameter of the plurality of collet members.
The plurality of collet members have a flange portion formed at a lower end portion so that an annular piston member of the fluid pressure cylinder faces from above,
A tapered driven surface that is formed on the inner peripheral portion of the flange portion of the plurality of collet members and has a taper driven surface that increases in diameter downward, a tapered engagement surface that engages with the tapered driven surface, and the annular engagement The clamp device according to claim 5, further comprising a second guide mechanism including a compression spring that elastically biases the member upward.
The plurality of collet members have a flange portion formed at a lower end portion so that an annular piston member of the fluid pressure cylinder faces from above,
A third guide mechanism provided with a tapered driven surface formed on the upper surface of the flange portion and having a smaller diameter toward the upper side, and a tapered pressing surface formed on the annular piston member so as to contact the tapered driven surface is provided. The clamping device according to claim 6.
The plurality of collet members have a flange portion formed at a lower end portion so that an annular piston member of the fluid pressure cylinder faces from above,
A rotation restricting mechanism is provided between the upper surface portion of the flange portion and the annular piston member. The rotation restricting mechanism allows the reduction / expansion of the plurality of collet members and restricts the rotation of the plurality of collet members around the vertical axis. The clamping device according to any one of claims 3 to 7.