JP2011143531A - Clamp device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably close a valve member for detecting clamping defects in a clamp device. <P>SOLUTION: The clamp device includes a pull rod (6) and a piston (9) arranged vertically within a housing (2), a locking tool (17) arranged on an outer periphery of an upper portion of the pull rod (6), a support member (14) supporting the locking tool (17) from the lower side, and a coned disc spring (29) pressing the support member (14) up. A valve member (54) is hermetically inserted into a valve chamber (53) provided in the housing (2) to be vertically movable. By supplying compressed air to a supply passage (49), the compressed air delivered into a pressurizing chamber (57) through a through hole (62) of the valve member (54) lifts the valve member (54) to maintain the valve member (54) in a closed state. When clamping defects arise in which the support member (14) is lowered below a predetermined region, an operation portion (71) provided on the support member (14) presses the valve member (54) downward to open the valve member. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a clamp device of a type in which an engagement tool is engaged with a hole provided in an object to be fixed such as a work and is pulled and fixed to a support base such as a work pallet. More specifically, a clamp failure is detected. The present invention relates to a clamping device provided with a mechanism.

Conventionally, there is a clamp apparatus provided with this type of clamp failure detection mechanism described in Patent Document 1 (Japan, JP-A-2009-190137). The prior art is configured as follows.
A pull rod and a piston are arranged vertically in the housing, an engaging tool is arranged on the outer periphery of the upper part of the pull rod, and the engaging tool is supported from below by the oil pressure applied to the annular pressure receiving member. And when the piston drives the pull rod downward, the inclined surface provided on the pull rod moves the engagement tool supported by the annular pressure receiving member outward in the radial direction, and then The engagement tool and the annular pressure receiving member are lowered against the oil pressure.
When the engagement tool and the annular pressure receiving member are lowered from a predetermined region for some reason, the collar member of the annular pressure receiving member is closed to the O ring by the elastic force of the O ring. The valve is forcibly tilted against the valve to open, and the pressure drop of the compressed air due to the valve opening is detected.

  JP 2009-190137 A

The above prior art has the following problems.
In order to close the valve member by the elastic force of the O-ring, it is necessary to compress the O-ring in advance. As described above, since the O-ring is always compressed, there is a possibility that the elastic force is lost due to deterioration over time and a valve closing failure may occur.
Moreover, when the valve member is opened when the clamp is defective, the already compressed O-ring is further pressed by the tilted valve member and partially compressed excessively. For this reason, the O-ring is damaged and the valve member cannot be closed reliably.
An object of the present invention is to reliably close a valve member for detecting a defective clamp.

Means for solving the problem

In order to achieve the above object, according to the present invention, for example, as shown in FIG. 1 to FIG. 3C, FIG. 4A to FIG. 4C, or FIG. 5A to FIG.
A pull rod 6 and a piston 9 arranged vertically in the housing 2, an engagement tool 17 arranged on the upper outer periphery of the pull rod 6, a support member 14 for supporting the engagement tool 17 from below, and its support Advancing means 29 for pushing up the member 14 with a predetermined force is provided. When the piston 9 drives the pull rod 6 downward, the output portion 21 provided on the pull rod 6 moves the engagement tool 17 supported by the support member 14 outward in the radial direction, Thereafter, the engaging tool 17 and the support member 14 are moved down against the advancement means 29.
Between the valve chamber 53 provided in the housing 2, a valve member 54 that can be moved up and down in the valve chamber 53 and inserted in an airtight manner, and between the lower wall 53 a of the valve chamber 53 and the valve member 54. The pressure chamber 57 formed in the above, the throttle chamber 58 formed between the upper wall 53b of the valve chamber 53 and the valve member 54, and the upper wall 53b of the valve chamber 53 are opened. A compressed air supply passage 49, a through hole 62 formed in the valve member 54 in the vertical direction so as to supply compressed air to the pressurizing chamber 57, and a discharge passage 63 capable of communicating with the throttle chamber 58. And a valve seat 68 provided on the upper wall 53b of the valve chamber 53 and a valve surface 69 provided on the upper part of the valve member 54 so as to face the valve member 54 from above with a predetermined gap. And an operation portion 71 provided on the support member 14 or the piston 9. By supplying compressed air to the supply passage 49, the compressed air flowing into the pressurizing chamber 57 through the through hole 62 raises the valve member 54, and the valve surface 69 is The valve seat 68 is configured to contact the valve seat 68. In the contact state, the valve member 68 and the valve surface 69 are configured so that the pressure receiving area on the upper surface side is smaller than the pressure receiving area on the lower surface side of the valve member 54, and the valve member 54 is configured. The valve member 54 is held in a closed state by an upward differential force acting on the valve. When the support member 14 or the piston 9 is lowered from a predetermined region, the operation unit 71 pushes the closed valve member 54 downward to move the valve surface 69 from the valve seat 68. The compressed air in the supply passage 49 is configured to leak to the discharge passage 63.

The present invention has the following effects.
In a normal clamping state, the compressed air supplied to the compressed air supply passage hardly flows into the throttle chamber, but flows in a large amount through the through hole into the pressurizing chamber. For this reason, the differential pressure acting on the upper and lower sides of the valve member raises the valve member so that the valve surface comes into contact with the valve seat, and then the force acting on the pressure receiving area on the lower surface side of the valve member, The valve member is held in a closed state by a differential force from the force acting on the pressure receiving area on the upper surface side. Therefore, the pressure in the supply path rises to the set pressure, and the normal clamping state can be confirmed by detecting the pressure.
On the other hand, in the state where the clamping failure is caused for some reason, the support member or the piston is excessively lowered beyond a predetermined region, so that the operation unit pushes the valve member in the closed state downward. As a result, the valve face is separated from the valve seat. For this reason, the pressure in the supply path does not reach the set pressure, and by detecting the pressure, it can be confirmed that the clamp is in a defective state.
Therefore, unlike the above-described prior art, the present invention eliminates the need to provide an O-ring that elastically biases the valve member toward the closing side. For this reason, the above-mentioned problems caused by aging deterioration and excessive compression of the O-ring can be solved, and the valve member for detecting a clamping failure can be reliably closed.

  In the present invention, for example, as shown in FIGS. 1 to 3C, it is preferable to provide the operation portion 71 on the support member 14.

  Further, in the present invention, as shown in FIGS. 3A to 3C or FIGS. 4A to 4C, the sealing member 55 for sealing the peripheral wall 53c of the valve chamber 53 and the outer peripheral portion of the valve member 54 is provided. The valve member 54 is preferably attached.

  It is sectional drawing of the elevation view which shows one Embodiment of the clamp apparatus of this invention, and is an unclamp state.   It is a figure similar to FIG. 1 which shows the clamp defect state of the said clamp apparatus.   3A to 3C are operation explanatory views of the mechanism for detecting the clamping failure. FIG. 3A shows an unloaded state of the valve member provided in the clamp failure detection mechanism. FIG. 3B shows a closed state of the valve member, and corresponds to an enlarged view of a 3B portion in FIG. 1. FIG. 3C shows the opened state of the valve member, and corresponds to an enlarged view of a 3C portion in FIG. 2.   4A to 4C show a first modification, and are similar to FIGS. 3A to 3C, respectively.   5A to 5C show a second modified example and are similar to FIGS. 3A to 3C, respectively.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3C. First, the structure of the clamping device will be described with reference to FIG.
A housing 2 is fixed to a base plate 1 placed on a table of a machine tool by a plurality of bolts (not shown). The housing 2 includes an upper housing 3 and a lower housing 4. These upper and lower housings 3 and 4 are fastened by a plurality of bolts (not shown).
A pull rod 6 is arranged in the upper part of the housing 2 so as to be movable in the vertical direction and in the radial direction. In the lower part of the housing 2, the piston 9 of the hydraulic cylinder 8 is arranged in a tightly-tight manner so as to be movable in the vertical direction.

  On the outer periphery of the pull rod 6, a collet 13 inserted into the hole 12 of the workpiece 11 and an annular support member 14 movable in the vertical direction are arranged vertically. A seating surface 15 for receiving the lower surface 11 a of the work 11 is formed in an annular shape on the upper surface of the upper housing 3 at the outer peripheral portion of the collet 13.

The collet 13 includes four grippers 16 arranged at a predetermined interval in the circumferential direction. Each gripper 16 includes an engagement tool 17, an upper flange 18, and a lower flange 19 arranged in order from above, and these members 17, 18, 19 are integrally formed.
A saw blade-like protrusion 17 a is formed on the outer periphery of each engagement tool 17. Moreover, the inclined surface 17b is formed in the inner periphery of each engaging tool 17 so that it may approach an axial center as it goes below. Corresponding to the inclined surface 17b, four inclined surfaces (output portions) 21 are provided on the upper portion of the pull rod 6. In this embodiment, the inclined surfaces 17b and 21 are formed as flat surfaces.

  The four grippers 16 are urged inward in the radial direction by the elastic force of the O-ring 23 mounted between the upper and lower flanges 18 and 19, and the elastic force of the dust seal 24 mounted on the upper portion of the upper housing 3. Is also urged radially inward.

  The annular support member 14 includes a large-diameter portion 26 that supports the four grippers 16 from below, and a small-diameter portion 27 that protrudes downward from the large-diameter portion 26. The large-diameter portion 26 is supported by a large-diameter hole 3a provided in the lower portion of the upper housing 3 so as to be movable up and down. A plurality of disc springs 29 are stacked in a spring chamber provided between the small diameter portion 27 and the upper hole 4a of the lower housing 4, and the disc springs 29 bias the large diameter portion 26 upward. is doing. That is, in this embodiment, the disc spring 29 described above constitutes an advancing means that pushes up the support member 14 with a predetermined force.

  The piston 9 of the hydraulic cylinder 8 is inserted into a stepped hole 4 b formed in the lower housing 4, and includes a piston body 31, a piston rod 32, and an end plate 33. A lower flange 35 of the pull rod 6 is fitted between the upper end portion of the piston rod 32 and the end plate 33 so as to be movable in the radial direction. A U-shaped elastic body 37 is mounted between the pull rod 6 and the support member 14. The pull rod 6 is pushed inward in the radial direction by the urging force of the elastic body 37 and is returned coaxially with the axis of the piston 9.

  A lock chamber 41 is formed above the piston body 31 and a release chamber 42 is formed below the piston body 31. The lock chamber 41 communicates with the pressure oil supply / discharge port 46 for locking via a vertical path 44 in the lower housing 4 and a horizontal path 45 in the upper housing 3. The release chamber 42 communicates with a pressure oil supply / discharge port (not shown) for release.

  A seating detection hole 48 is opened in the seating surface 15 formed in the upper part of the upper housing 3. The detection hole 48 communicates with the compressed air supply port 50 through the compressed air supply path 49.

The clamp device having the above-described configuration is provided with a detection mechanism for defective clamping. As shown in FIGS. 1 and 3A, the detection mechanism is configured as follows.
A valve chamber 53 is provided between the upper housing 3 and the lower housing 4 in the vicinity of the large-diameter portion 26 of the support member 14. The valve member 54 is vertically movable and inserted in the valve chamber 53 in an airtight manner. In this embodiment, an O-ring (sealing tool) 55 that seals the peripheral wall 53 c of the valve chamber 53 and the outer peripheral portion of the valve member 54 is attached to the middle height portion of the valve member 54. In this case, the O-ring 55 reduces the friction force acting between the peripheral wall 53c of the valve chamber 53 by setting the crushing margin to a small value or coating the surface with a synthetic resin. Is preferred.

  A pressurizing chamber 57 is formed between the lower wall 53 a of the valve chamber 53 and the valve member 54, and a throttle chamber 58 is formed between the upper wall 53 b of the valve chamber 53 and the valve member 54. It is formed. A detection hole 60 with poor clamping is branched from the compressed air supply passage 49, and the detection hole 60 is opened in the upper wall 53 b of the valve chamber 53. The compressed air supplied to the detection hole 60 is supplied to the pressurizing chamber 57 through a large-diameter through hole 62 formed in the valve member 54. On the other hand, the throttle chamber 58 is formed thin so that the compressed air in the detection hole 60 does not easily flow into the upper side of the valve member 54. A discharge path 63 communicates with the throttle chamber 58. The discharge path 63 includes a vertical groove 64 formed in the large-diameter hole 3 a of the upper housing 3, a circumferential gap formed between adjacent grippers 16, and an upper surface groove 65 provided in the seating surface 15. And can communicate with the outside of the upper housing 3. If the predetermined passage area can be secured by the fitting gap between the outer peripheral surface of the support member 14 and the large-diameter hole 3a, the vertical groove 64 may be omitted.

A valve path 67 that opens and closes between the detection hole 60 of the poor clamping and the discharge path 63 is provided. More specifically, a valve seat 68 is formed on the upper wall 53 b of the valve chamber 53 between the lower end of the detection hole 60 and the lower end of the vertical groove 64, and a valve surface 69 is formed on the upper portion of the valve member 54. Is done. The valve passage 67 is formed between the valve seat 68 and the valve surface 69. As shown in FIG. 3B described later, when the valve surface 69 is in contact with the valve seat 68, the pressure receiving area on the upper surface side is smaller than the pressure receiving area on the lower surface side of the valve member 54. Thus, the above-described valve seat 68 and the above-described valve surface 69 are configured.
The valve member 54 is provided with an operating portion 71 that faces from above with a predetermined gap. In this embodiment, the operation portion 71 is configured by a lower portion of the outer peripheral portion of the large diameter portion 26 of the support member 14.

In a no-load state in which compressed air is not supplied to the detection hole 60, as shown in FIG. 3A, the valve member 54 is lowered, the valve surface 69 is separated from the valve seat 68, and the valve passage 67 is is open. When compressed air is supplied to the detection hole 60, the compressed air hardly flows into the throttle chamber 58, but flows in a large amount into the pressurizing chamber 57 through the large-diameter through hole 62. . For this reason, as shown in FIG. 3B, the pressure in the pressurizing chamber 57 is rapidly increased, the valve member 54 is raised by the differential pressure acting on the upper side and the lower side of the valve member 54, and the valve surface 69 is The valve path 67 is closed by contacting the valve seat 68. Thereafter, the valve member 54 is held in a closed state by the differential force between the force acting on the pressure receiving area on the lower surface side of the valve member 54 and the force acting on the pressure receiving area on the upper surface side.
If the support member 14 is excessively lowered for some reason, as shown in FIG. 3C, the operation unit 71 pushes the valve member 54 in the closed state downward, thereby The valve surface 69 is separated from the seat 68 and the valve passage 67 is opened.

As shown in FIGS. 1 and 2, the clamping device having the above-described configuration operates as follows.
In the unclamped state shown in FIG. 1 (and FIG. 3B), the pressure oil in the lock chamber 41 is discharged and the pressure oil is supplied to the release chamber 42. As a result, the piston 9 and the pull rod 6 are raised, the support member 14 and the collet 13 are held in the raised position, and the four grippers 16 of the collet 13 are switched to a reduced diameter state by the elastic force of the O-ring 23. ing.

  In the unclamped state, the work 11 is lowered by some lifting means or its own weight, and the collet 13 is inserted into the hole 12 of the work 11. Then, the lower surface 11a of the workpiece 11 comes into contact with the upper flange 18 of the gripper 16, and the weight of the workpiece 11 is supported in a state where a slight gap G is formed between the lower surface 11a and the seating surface 15. It is received by the disc spring 29 via the member 14. Accordingly, even if compressed air is supplied to the seating detection hole 48 in this state, the detection pressure does not increase due to leakage from the gap G.

When the clamp device is switched from the unclamped state to the clamped state, the pressure oil in the release chamber 42 is discharged and the pressure oil is supplied to the lock chamber 41.
Then, the pull rod 6 descends with respect to the support member 14 and the gripper 16 held in the raised position by the urging force of the disc spring 29, so that the gripper 16 is enlarged in diameter and the engagement provided on the gripper 16 is provided. The fitting 17 engages with the hole 12 of the workpiece 11. Subsequently, the pulling force of the pull rod 6 causes the engaging tool 17 in close contact with the inner peripheral surface of the hole 12 to pull the work 11 downward through the hole 12, and at the same time, the gripper 16 and the support The member 14 descends against the biasing force of the disc spring 29. As a result, the lower surface 11a of the workpiece 11 is brought into contact with the seating surface 15 of the housing 2 to eliminate the gap G, and the workpiece 11 is strongly pressed against the seating surface 15.

When compressed air is supplied to the seating detection hole 48 in the clamped state, the detected pressure increases, so that the seated state can be confirmed.
Further, in the clamped state, the support member 14 is slightly lowered by a dimension slightly larger than the gap G, so that the gap between the operation portion 71 of the support member 14 and the valve member 54 is small. There is a contact gap left. For this reason, the compressed air supplied to the pressurizing chamber 57 holds the valve member 54 in the raised position, and the valve path 67 is closed. Thereby, since the detection pressure of the detection hole 60 of the clamping failure increases, the above clamping state can be confirmed.

  When switching from the clamped state to the unclamped state, the pressure oil in the lock chamber 41 may be discharged and the pressure oil supplied to the release chamber 42.

  By the way, as in the case where the diameter of the hole 12 of the workpiece 11 is larger than the allowable range, for some reason, slipping occurs between the inner peripheral surface of the hole 12 and the engagement tool 17 whose diameter has been enlarged when the clamp is driven. May occur. In this case, as shown in FIG. 2, the pull rod 6, the piston 9, the support member 14, and the gripper 16 are excessively lowered by overstroke from a predetermined clamp stroke region.

  When the clamping failure is as described above, as shown in FIG. 2, the operation portion 71 of the support member 14 that has been lowered excessively tilts the valve member 54 to lower it (see FIG. 3C). Then, the valve surface 69 of the valve member 54 is separated from the valve seat 68 and the valve passage 67 is opened, and the compressed air supplied to the detection hole 60 with poor clamping is the valve passage 67 and the discharge passage 63. It is discharged to the outside through. For this reason, it can be confirmed that the pressure of the detection hole 60 does not increase and the clamping is defective.

  4A to 4C and FIGS. 5A to 5C show a first modification and a second modification, respectively. In these modified examples, the same members (or similar members) as the constituent members of the above-described embodiment are described with the same reference numerals in principle.

  4A to 4C, the O-ring (sealing tool) 55 is attached to the lower part of the valve member 54.

The second modification of FIGS. 5A to 5C is different from the above-described embodiment in the following points.
The outer peripheral surface of the valve member 54 is formed by a taper surface 74 that narrows upward, and the lower portion of the taper surface 74 is fitted into the peripheral wall 53c of the valve chamber 53 in an airtight manner. Thereby, the O-ring (sealing tool) 55 of the above-described embodiment and the first modification is omitted.

The above embodiments and modifications can be further modified as follows.
The structure for moving the valve member 54 from the lowered position to the raised position is not particularly limited as long as it applies an upward differential pressure to the valve member 54, and instead of mounting the O-ring (sealing tool) 55. Thus, a labyrinth seal may be provided between the peripheral wall 53c of the valve chamber 53 and the outer peripheral portion of the valve member 54.
The advance means may be another type of spring such as a compression coil spring or an elastic body such as rubber instead of the illustrated disc spring 29, or may use a pressure fluid such as pressure oil (described above). Japanese Patent Application Laid-Open No. 2009-190137, etc., which is a prior art of the above).
The compressed air supply passage 49 may be provided separately for both the seating detection hole 48 and the clamping failure detection hole 60 instead of being shared by both.
The operation portion 71 for forcibly opening the valve member 54 can be provided in the piston 9 instead of being provided in the support member 14.
The collet 13 may be any structure that expands and contracts in the diameter direction, and is not limited to the illustrated structure. Further, the output portion of the pull rod 6 for moving the gripper 16 of the collet 13 outward in the radial direction is replaced with the inclined surface 21 formed integrally with the pull rod 6, and is connected to the pull rod 6. You may comprise by this member.
Instead of the illustrated hydraulic double-acting type, the clamping device of the present invention may be of a type that is locked by a spring force and released by a hydraulic pressure, or a type that is locked by a hydraulic pressure and released by a spring force. . The working fluid of the clamp device may be compressed air instead of pressurized oil.
A fixed object to which the present invention is applied may be a work pallet or a mold instead of the work 11.
In addition, it is needless to say that various modifications can be made within a range that can be assumed by those skilled in the art.

2: housing, 6: pull rod, 9: piston, 14: support member, 17: engagement tool, 21: output portion (inclined surface) of pull rod 6, 29: advance means (disc spring), 49: supply of compressed air Road, 53: valve chamber, 53a: lower wall, 53b: upper wall, 53c: peripheral wall, 54: valve member, 55: sealing tool (O-ring), 57: pressurizing chamber, 58: throttle chamber, 62: penetration Hole, 63: discharge path, 68: valve seat, 69: valve face, 71: operation part.

Claims (3)

A pull rod (6) and a piston (9) arranged vertically in the housing (2), an engagement tool (17) arranged on the upper outer periphery of the pull rod (6), and the engagement tool (17) A support member (14) for supporting the support member (14) from below, and an advancing means (29) for pushing up the support member (14) with a predetermined force,
When the piston (9) drives the pull rod (6) downward, the output part (21) provided on the pull rod (6) is supported by the engagement member (14) supported by the support member (14). 17) a clamp configured to move radially outward and then lower the engagement tool (17) and the support member (14) against the advancement means (29). A device,
A valve chamber (53) provided in the housing (2); a valve member (54) which is vertically movable in the valve chamber (53) and inserted in an airtight manner; and a lower wall of the valve chamber (53) (53a) between the pressurizing chamber (57) formed between the valve member (54) and the upper wall (53b) of the valve chamber (53) and the valve member (54). The compressed chamber is formed in the throttle chamber (58), the compressed air supply passage (49) is opened in the upper wall (53b) of the valve chamber (53), and the pressurized chamber (57) is supplied with compressed air. A through hole (62) formed in the valve member (54) in the vertical direction so as to supply, a discharge passage (63) communicated with the throttle chamber (58), and the valve chamber (53) A predetermined gap is provided between the valve seat (68) provided on the upper wall (53b) and the valve surface (69) provided above the valve member (54) and the valve member (54). Opened with the operation unit provided on said support member so as to face the upper side (14) or piston (9) and (71), the, the
By supplying compressed air to the supply passage (49), the compressed air flowing into the pressurizing chamber (57) through the through hole (62) raises the valve member (54). The valve surface (69) is in contact with the valve seat (68), and in this contact state, the pressure receiving surface on the upper surface side is larger than the pressure receiving area on the lower surface side of the valve member (54). The valve seat (68) and the valve surface (69) are configured to reduce the area, and the valve member (54) is closed by an upward differential force acting on the valve member (54). Hold on
When the support member (14) or the piston (9) is lower than a predetermined region and the clamp is defective, the operation unit (71) pushes the closed valve member (54) downward to thereby provide the valve surface. A clamp apparatus characterized in that (69) is separated from the valve seat (68) and the compressed air in the supply passage (49) is leaked to the discharge passage (63). The clamping device according to claim 1, wherein
The clamp device according to claim 1, wherein the operation portion (71) is provided on the support member (14). The clamping device according to claim 1 or 2,
A sealing tool (55) for sealing the peripheral wall (53c) of the valve chamber (53) and the outer peripheral portion of the valve member (54) is mounted on the valve member (54). Clamping device.

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