Clamp device

Abstract

To provide a clamp device which can maintain an unclamped state without exerting an external force thereon continuously.SOLUTION: A clamp device includes an operation rod (27). The operation rod (27) has: an operation rod body (28) in which protruding parts (31) are provided on an outer peripheral surface; a movable member (29); and a spring (30). An inner surface of a housing (1) is provided with a cam groove (40) in which the protruding parts (31) are disposed and which fixes the operation rod body (28) at a position to which the operation rod body (28) is moved in a tip side direction when the operation rod body (28) is pushed into the housing (1) and allows movement of the operation rod body (28) in a base end side direction when the operation rod body (28) is pushed into the housing (1) again.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a clamping device. [Background technology]

[0002] An example of a clamping device is described in the following Patent Document 1. This clamping device according to the prior art is configured as follows.

[0003] The clamping device is composed of a cylindrical plug portion protruding from a housing, an output rod, an engaging ball, a piston, etc. The housing constituting the clamping device is provided with a clamping chamber and an unclamping chamber to which a pressurized fluid is supplied and discharged. Compressed air, for example, is used to drive the clamping device, i.e., the piston and the output rod, and compressed air is supplied to and discharged from the clamping chamber and the unclamping chamber each time the device is driven. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 177385 Summary of the Invention [Problem to be solved by the invention]

[0005] When a large number of clamping devices as described above are installed, a large-scale facility is required as a compressed air supply facility. In addition, the piping facilities for supplying and discharging the compressed air are numerous and complicated. These are undesirable from the viewpoints of energy saving and environmental measures. Therefore, it is desirable to eliminate the need for compressed air as a driving source.

[0006] In response to the above, the applicant has developed a clamping device that does not require a pressurized fluid such as compressed air for operation, or that can be operated without supplying a pressurized fluid each time it is operated, and has filed a patent application (Patent Application No. 2022-152081).

[0007] However, the clamp device described in the above-mentioned Japanese Patent Application No. 2022-152081 has the following problem: In the clamp device, in order to maintain the unclamped state, it is necessary to continue to apply an external force to a ball serving as an operating member.

[0008] An object of the present invention is to provide a clamping device that can maintain an unclamped state without the continued application of an external force. [Means for solving the problem]

[0009] In order to achieve the above object, the clamp device disclosed in the present application is configured as follows, for example, as shown in FIGS. 1A to 7.

[0010] (1) A clamp device includes a housing 1, a clamp rod 5 arranged in the housing 1 so as to be movable in the axial direction, an operating rod 27 arranged in series with the clamp rod 5 in the housing 1, the operating rod 27 being rotatable about its axis and pushing the clamp rod 5 in the axial direction toward the tip end, and a first biasing means 11 arranged inside the tip side of the housing 1 and pushing the clamp rod 5 in the axial direction toward the base end. The operating rod 27 has an operating rod main body 28 that is rotatable about its axis and has a convex portion 31 on its outer circumferential surface, a movable member 29 arranged in a bottomed cylindrical hole 28c formed on the tip side of the operating rod main body 28, the movable member 29 pushing the clamp rod 5 in the tip end direction, and a second biasing means 30 arranged in the cylindrical hole 28c and capable of expanding and contracting, which biases the movable member 29 in the tip end direction relative to the operating rod main body 28. A cam groove 40 in which the protrusion 31 is disposed is formed on the inner surface of the housing 1. When the operating rod body 28 is pushed into the housing 1, the cam groove 40 fixes the operating rod body 28 at a position to which it has moved toward the tip side, and when the operating rod body 28 is pushed into the housing 1 again, allows the operating rod body 28 to move toward the base end side.

[0011] The clamp device disclosed in the present application has the following operational effects. The clamp device includes a convex portion provided on the outer peripheral surface of the operating rod body, and a cam groove in which the convex portion is disposed. When the operating rod body is pushed into the housing, the operating rod body is fixed at a position to which it has moved toward the tip side by the convex portion and the cam groove. Since the clamp rod is disposed in series with the operating rod, the clamp rod is also fixed at a position to which it has moved toward the tip side. As a result, the clamp device can maintain an unclamped state without continuously applying an external force to the operating rod body. The unclamped state is a state in which the clamp rod has moved toward the tip side.

[0012] Furthermore, since the operating rod is composed of the operating rod body, the movable member, and the second biasing means, the operating rod can be smoothly rotated even in the case of a clamp rod that has a short axial movement distance.

[0013] (2) In the clamp device of (1) above, the first biasing means 11 and the second biasing means 30 are both springs, and the spring constant of the second biasing means 30 may be greater than the spring constant of the first biasing means 11.

[0014] According to this configuration, the clamp rod can be reliably moved in the distal direction, and the clamp rod that has been moved in the distal direction can be reliably held in that position.

[0015] (3) In the clamp device of (1) or (2) above, the cam groove 40 may have a straight groove 40a extending in the axial direction and a zigzag-shaped swivel groove 40b extending from the tip of the straight groove 40a in the circumferential direction of the operating rod main body 28, for rotating the operating rod main body 28.

[0016] With this configuration, the cam groove can be easily formed.

[0017] (4) In the clamp device of (3) above, the swiveling groove 40b may have a tip-side inclined portion 40b3 that is inclined relative to the circumferential direction of the operating rod main body 28, the tip-side inclined portion 40b3 serving as a swiveling guide for the convex portion 31, and a base-side recessed portion 40b2 formed on the base end side relative to the tip-side inclined portion 40b3, into which the convex portion 31 fits to fix the operating rod main body 28.

[0018] With this configuration, the cam groove can be easily formed.

[0019] (5) In the clamp device of (4) above, the swiveling groove 40b may further include a tip-side recess 40b1 formed adjacent to the tip-side inclined portion 40b3, into which the protrusion 31 fits, and a base-side inclined portion 40b4 formed between the straight groove 40a and the base-side recess 40b2 in the circumferential direction of the operating rod body 28, which serves as a swiveling guide for the protrusion 31.

[0020] With this configuration, the cam groove can be easily formed.

[0021] (6) In any one of the clamp devices described above in (3) to (5), the rectilinear grooves 40a may be provided in plurality at equal intervals in the circumferential direction of the operating rod body 28.

[0022] According to this configuration, it is possible to reduce the rotation angle of the operating rod body per one time when the operating rod body is pushed into the housing.

[0023] (7) In the clamp device of (6) above, the convex portions 31 may be provided at equal intervals in the circumferential direction of the operating rod body 28, the number of which is the same as the number of the rectilinear grooves 40a.

[0024] According to this configuration, the force received by the protrusion can be dispersed, and the movement of the operating rod body, including its rotation, can be made smoother.

[0025] (8) In any of the clamp devices (1) to (7) above, the convex portion 31 may be a rotatable sphere 31, and the sphere 31 may be disposed in a hole 28a formed in the outer peripheral surface of the operating rod main body 28.

[0026] According to this configuration, friction between the convex portion and the cam groove can be reduced, and the movement of the operating rod body, including its rotation, can be made smoother.

[0027] (9) In any one of the clamp devices (1) to (8) above, a rotatable spherical operating member 36 may be disposed at the base end side end of the operating rod body 28.

[0028] According to this configuration, the operating rod body can be pushed and moved by the operating member provided separately from the operating rod body, and the movement of the operating rod body, including its rotation, can be made smooth.

[0029] (10) In any of the clamp devices (1) to (9) above, a spherical rotatable power transmission member 6 may be disposed between the clamp rod 5 and the movable member 29.

[0030] According to this configuration, it is possible to reduce friction between the clamp rod and the movable member, and it is possible to smoothly rotate the operating rod (the operating rod main body).

[0031] (11) In any of the clamp devices (1) to (10) above, for example, as shown in Figures 1A to 5B, a cylindrical plug portion 4 into which the clamp rod 5 is inserted may be provided at the tip of the housing 1. The clamp device may also include an engaging member 15 that is inserted into a through hole 14 formed in a peripheral wall of the plug portion 4, and that is movable within the through hole 14 as the clamp rod 5 is moved in the axial direction, and is capable of abutting against a locking portion 25 of a mounting hole 24 provided in the clamp object WP so that the plug portion 4 can be inserted. Effect of the Invention

[0032] According to the present invention, it is possible to provide a clamping device that can maintain an unclamped state without the continuous application of an external force. [Brief description of the drawings]

[0033] [Figure 1A] FIG. 1A illustrates one embodiment of a clamping device and is a cross-sectional side view of the clamping device in a clamped state. [Figure 1B]FIG. 1B is a partial development view of a cam groove portion when the clamp device is in the state of FIG. 1A. [Figure 2A] FIG. 2A is a side cross-sectional view of the clamp device shown in FIG. 1A when the operating rod body is pushed into the housing. [Figure 2B] FIG. 2B is a partial development view of the cam groove portion when the clamp device is in the state of FIG. 2A. [Figure 3A] FIG. 3A is a side cross-sectional view of the clamp device shown in FIG. 2A when the operating rod body is further pressed into the housing. [Figure 3B] FIG. 3B is a partial development view of the cam groove portion when the clamp device is in the state of FIG. 3A. [Figure 4A] FIG. 4A is a side cross-sectional view of the clamp device shown in FIG. 3A when an external force acting on an operating member is released and a work pallet WP is raised. [Figure 4B] FIG. 4B is a partial development view of the cam groove portion when the clamp device is in the state of FIG. 4A. [Figure 5A] FIG. 5A is a side cross-sectional view of the clamp device shown in FIG. 4A when the work pallet WP is lowered and the operating rod body is pushed into the housing. [Figure 5B] FIG. 5B is a partial development view of the cam groove portion when the clamp device is in the state of FIG. 5A. [Figure 6] FIG. 6 shows a modified example of the clamp device, and is a sectional side view of the clamp device in a clamped state. [Figure 7] FIG. 7 shows a modified example of the clamp device, and is a sectional side view of the clamp device in a clamped state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] 1A to 5B show an embodiment of the clamp device. First, the configuration of this clamp device will be described. The clamp device fixes a work pallet WP, which is an object to be clamped, to a clamp pallet CP as a base. The clamp device includes a housing 1, a clamp rod 5, and an operating rod 27.

[0035] The housing 1 is fixed to the clamp pallet CP by a plurality of bolts (not shown). The housing 1 is composed of a housing main body 2 and a housing second main body 3 attached to the end face of the housing main body 2 on the base end side.

[0036] A cylindrical plug portion 4 protrudes upward integrally from the housing body 2. The plug portion 4 is a part of the housing body 2. An upper rod portion 5a of a clamp rod 5 is inserted into a plug portion cylindrical hole 4a of the plug portion 4 so as to be movable up and down (the axial direction of the plug portion cylindrical hole 4a). The axial direction of the clamp rod 5 and the axial direction of the plug portion cylindrical hole 4a are the same.

[0037] A cylindrical hole 2a is formed on the base end side of the housing body 2, and a lower rod portion 5b of the clamp rod 5 is inserted into this cylindrical hole 2a so as to be movable in the vertical direction. The cylindrical hole 2a has a larger diameter than the plug portion cylindrical hole 4a. The plug portion cylindrical hole 4a and the cylindrical hole 2a are formed so as to be connected vertically. The axial direction of the cylindrical hole 2a and the axial direction of the plug portion cylindrical hole 4a are the same.

[0038] A step 5c is provided at the tip end portion of the lower rod portion 5b (the middle portion in the axial direction of the clamp rod 5). This step 5c limits the upward (tip end) movement of the clamp rod 5. When the step 5c hits the inner surface of the housing main body 2, the clamp rod 5 cannot rise any further.

[0039] A ball 6 (sphere) as a power transmission member is rotatably arranged at the base end of the lower rod portion 5b. The ball 6 is, for example, a metal ball. In this embodiment, the ball 6 is arranged in a recess 7 formed on the base end face of the lower rod portion 5b. The ball 6 is prevented from falling out of the recess 7 by a retaining ring 9 (a ring-shaped stopper). The retaining ring 9 is attached to the inner peripheral surface of the recess 7. A part of the ball 6 protrudes from the end face of the lower rod portion 5b toward the outside in the axial direction of the clamp rod 5. In addition, a plurality of balls 8 are arranged between the bottom surface of the recess 7 and the ball 6 as a bearing member for the power transmission member. The ball 8 is, for example, a metal ball. The ball 8 can receive the axial load of the clamp rod 5. Since the ball 8 is accommodated in the recess 7, it can also receive a part of the load in a direction perpendicular to the axial direction.

[0040] The base end of the lower rod portion 5b where the recess 7 is formed is a piston portion 10 (large diameter portion) and has a larger diameter than other portions of the clamp rod 5. A spring 11 is disposed in the space above the piston portion 10 in the cylindrical hole 2a as a first biasing means for pushing the piston portion 10 downward (toward the base end). The spring 11 is a compression coil spring. The spring 11 in this embodiment is composed of a first spring 11a and a second spring 11b. The diameter of the second spring 11b is larger than the diameter of the first spring 11a. On the upper surface (tip side surface) of the piston portion 10, a first step portion 10a that receives the lower end of the first spring 11a and a second step portion 10b that receives the lower end of the second spring 11b are provided in this order from the inside. A ring-shaped spring bearing 12 that receives the upper end of the first spring 11a is provided on the first spring 11a, and a ring-shaped spring bearing 13 that receives the upper end of the second spring 11b is provided on the second spring 11b.

[0041] The spring 11 is not limited to being made up of two springs. Also, instead of a compression coil spring, other types of springs such as a disc spring may be used.

[0042] A plurality of through holes 14 are formed at a predetermined interval in the circumferential direction on the upper part of the peripheral wall of the plug portion 4. A ball 15 (engagement ball) as an engagement member is inserted into each through hole 14. Each ball 15 is movably supported between a position (inner position) shown in FIG. 2A, etc. inward in the radial direction and a position (outer position) shown in FIG. 1A outward in the radial direction by the through hole 14.

[0043] On the outer peripheral wall of the upper rod portion 5a of the clamp rod 5, a pressing surface 16 and a retreat groove 17 are formed side by side vertically corresponding to each ball 15. The pressing surface 16 is formed so as to widen as it goes upward. When the pressing surface 16 moves to a position facing the ball 15, the ball 15 is moved to the outer position so as to protrude outward in the radial direction from the outer peripheral surface of the plug portion 4. Further, when the retreat groove 17 moves to a position facing the ball 15 and to a retreat position where the ball 15 can be inserted, the ball 15 can move inward in the radial direction from the outer peripheral surface of the plug portion 4. In the present embodiment, four balls 15 are inserted into each through hole 14 one by one, but the number of balls 15 is not limited to four.

[0044] An annular collet 18 is fitted onto the lower portion (root portion) of the peripheral wall of the plug portion 4. The collet 18 has a tapered outer peripheral surface 18a that tapers upward, and is elastically reduced in diameter by a single slit 18b extending in the vertical direction. The collet 18 is prevented from coming off the plug portion 4 by a retaining ring 19 (upward movement is restricted). A plurality of through holes 21 into which a pressing member 20 that presses the collet 18 upward (toward the tip side) is inserted are formed at a predetermined interval in the circumferential direction on the upper surface 2b of the housing main body 2. The pressing member 20 is cylindrical and has a large diameter portion 20a (flange portion) at its lower end. At the large diameter portion 20a, the pressing member 20 is supported from below by the spring receiver 12. The collet 18 is urged upward by the first spring 11a via the pressing member 20 and the spring receiver 12. Therefore, the collet 18, whose upward movement is restricted by the retaining ring 19, can move slightly in the vertical direction. In this embodiment, three pressing members 20 are inserted into the through holes 21, one each, but the number of pressing members 20 is not limited to three.

[0045] A recess 22 is opened in the lower surface of the work pallet WP. A ring member 23 is attached to the recess 22, and the ring member 23 is fixed to the work pallet WP by a plurality of bolts (not shown). An attachment hole 24 is formed by an inner peripheral hole of the ring member 23, and the plug portion 4 can be inserted into the attachment hole 24.

[0046] A locking portion 25 is formed in the mounting hole 24 of the ring member 23 in a tapered shape so as to widen as it extends upward. Also, a tapered inner peripheral surface 26 that engages with the tapered outer peripheral surface 18a of the collet 18 is formed below the locking portion 25. The tapered inner peripheral surface 26 is a surface that tapers upward, in other words, is formed so as to narrow as it extends upward.

[0047] In this embodiment, the mounting hole 24 is formed in the ring member 23, but the mounting hole 24 may be configured by an inner peripheral hole of the recess 22 of the work pallet WP. In other words, the locking portion 25 and the tapered inner peripheral surface 26 may be formed in the inner peripheral hole itself of the recess 22 of the work pallet WP.

[0048] Inside the second housing main body 3, the operation rod 27 is arranged to be movable in the axial direction (vertical direction) and rotatable about the axis. The operation rod 27 is arranged in series with the clamp rod 5. The operation rod 27 is composed of an operation rod main body 28, a movable member 29, and a spring 30 as the second biasing means. The spring 30 is a compression coil spring. The axial direction of the clamp rod 5 and the axial direction of the operation rod main body 28 are the same direction.

[0049] The operation rod main body 28 is cylindrical, and a hole 28a is formed on the upper part of its outer peripheral surface, in which a ball 31 (sphere) as a convex part is arranged. The ball 31 is rotatably supported by the hole 28a. A plurality of balls 31 and holes 28a are respectively provided at predetermined intervals in the circumferential direction of the operation rod main body 28. Four balls 31 and holes 28a are respectively provided at equal intervals (90-degree intervals in this embodiment) in the circumferential direction of the operation rod main body 28. The same number of balls 31 as the straight groove 40a of the cam groove 40 described later are provided at equal intervals in the circumferential direction of the operation rod main body 28. Note that the number of balls 31 is not limited to four. Further, the convex part provided on the outer peripheral surface of the operation rod main body 28 is not limited to the ball 31. For example, the convex part may be a columnar object integral with the operation rod main body 28 protruding from the outer peripheral surface of the operation rod main body 28.

[0050] A spring 32 that pushes the operation rod main body 28 downward (toward the base end side) is arranged outside the lower part of the operation rod main body 28. The spring 32 is a compression coil spring. The upper end of the spring 32 is received by the second housing main body 3 of the housing. The lower end of the spring 32 is received by a ring-shaped spring receiver 33. A plurality of balls 34 are arranged between the spring receiver 33 and the flange part 28b at the lower end of the operation rod main body 28. The balls 34 are, for example, metal balls. Due to the presence of the rotatable balls 34, the spring receiver 33 is not restricted by the operation rod main body 28 in the axial direction. Therefore, the operation rod main body 28 is rotatable about the axis with respect to the spring receiver 33.

[0051] The spring constant of the spring 32 is sufficiently smaller (negligibly small) than the spring constants of both the spring 11 and the spring 30. The spring 32 is merely for suppressing rattling of the operation rod main body 28 and may be omitted. Since the spring 11 is composed of two springs, the spring constant of the spring 11 is the sum of the spring constants of the two springs (the first spring 11a and the second spring 11b).

[0052] A bottomed cylindrical hole 28c is formed on the tip side of the operation rod main body 28, and a columnar movable member 29 and a spring 30 (second biasing means) that can expand and contract are arranged in this cylindrical hole 28c. The upper end of the spring 30 is received by the flange portion 29a (large-diameter portion) of the movable member 29. The lower end of the spring 30 is received by the bottom surface of the cylindrical hole 28c. The spring 30 biases the movable member 29 upward (toward the tip side) with respect to the operation rod main body 28. The movable member 29 pushes and moves the clamp rod 5 upward (toward the tip side) via the ball 6 by the biasing force of the spring 30. A concave surface 29b into which the ball 6 fits is formed on the tip surface of the movable member 29. The movable member 29 is prevented from coming out of the cylindrical hole 28c by a retaining ring 35 (ring-shaped stopper). The retaining ring 35 is attached to the upper part of the inner peripheral surface of the cylindrical hole 28c. Further, a breathing hole 28d is provided on the bottom surface of the cylindrical hole 28c. When the movable member 29 descends in the cylindrical hole 28c, air is discharged from the breathing hole 28d, and conversely, when the movable member 29 ascends, outside air flows into the cylindrical hole 28c from the breathing hole 28d.

[0053] In the present embodiment, the spring constant of the spring 30 is made larger than the spring constant of the spring 11. Note that as the spring 30, it is also possible to use other types of springs such as a disc spring instead of a compression coil spring. The spring constant of the spring 30 may be the same as the spring constant of the spring 11 or smaller than the spring constant of the spring 11.

[0054] A ball 36 (sphere) as an operating member is rotatably arranged at the base end of the operating rod main body 28. The ball 36 is, for example, a metal ball. In this embodiment, the ball 36 is arranged in a recess 37 formed on the base end face of the operating rod main body 28. The ball 36 is prevented from coming out of the recess 37 by a retaining ring 39 (a ring-shaped stopper). A part of the ball 36 protrudes outward from the operating rod main body 28 in the axial direction of the operating rod main body 28. In addition, a plurality of balls 38 as bearing members for the operating member are arranged between the bottom surface of the recess 37 and the ball 36. The ball 38 is, for example, a metal ball. The ball 38 can receive a load in the axial direction of the operating rod 27. Since the ball 38 is accommodated in the recess 37, it can also receive a part of the load in a direction perpendicular to the axial direction.

[0055] The operating member is not limited to the ball 36 (sphere).

[0056] A cam groove 40 in which a ball 31 is disposed is formed on the inner surface of the housing second main body portion 3 constituting the housing 1. In this embodiment, the cam groove 40 is formed by machining the inner surface of the housing second main body portion 3 and by machining the end surface of the housing main body portion 2. Figures 1B, 2B, 3B, 4B, and 5B are partial development views of the cam groove 40 portion.

[0057] The cam groove 40 has a linear groove 40a extending in the axial direction of the operating rod body 28, and a zigzag-shaped swivel groove 40b extending in the circumferential direction of the operating rod body 28. The swivel groove 40b extends from the tip of the linear groove 40a in the circumferential direction of the operating rod body 28, and is formed so as to zigzag up and down (in the axial direction of the operating rod body 28). The swivel groove 40b is a groove for swivel the operating rod body 28.

[0058] The rectilinear grooves 40a are formed in the housing second main body portion 3. A plurality of the rectilinear grooves 40a are provided at predetermined intervals in the circumferential direction of the operating rod body 28. Four rectilinear grooves 40a are provided at equal intervals (90 degree intervals in this embodiment) in the circumferential direction of the operating rod body 28. The number of the rectilinear grooves 40a is not limited to four.

[0059] As shown in FIG. 1B and other figures, the zigzag-shaped swivel groove 40b has an upper recessed portion 40b1 (tip-side recessed portion) and a lower recessed portion 40b2 (base-side recessed portion). The upper recessed portion 40b1 is formed in the housing body 2. A plurality of upper recessed portions 40b1 are provided at predetermined intervals in the circumferential direction of the operating rod main body 28. Eight upper recessed portions 40b1 are provided at equal intervals (45 degree intervals in this embodiment) in the circumferential direction of the operating rod main body 28. The portion between the adjacent upper recessed portions 40b1 is an upper inclined portion 40b3 (tip-side inclined portion) inclined with respect to the circumferential direction of the operating rod main body 28. The upper inclined portion 40b3 serves as a swivel guide for the ball 31. The number of upper recessed portions 40b1 is not limited to eight. The number of upper recessed portions 40b1 is an even number.

[0060] The lower recessed portion 40b2 is formed in the housing second main body portion 3. A plurality of the lower recessed portions 40b2 are provided at predetermined intervals in the circumferential direction of the operating rod main body 28. Four lower recessed portions 40b2 are provided at equal intervals (90 degree intervals in this embodiment) in the circumferential direction of the operating rod main body 28. The number of lower recessed portions 40b2 is not limited to four.

[0061] When a plurality of rectilinear grooves 40a and a plurality of lower recessed portions 40b2 are provided, the rectilinear grooves 40a and the lower recessed portions 40b2 are provided alternately in the circumferential direction of the operating rod body 28. A portion between the rectilinear grooves 40a and the lower recessed portions 40b2 is a lower inclined portion 40b4 (base end side inclined portion) inclined with respect to the circumferential direction of the operating rod body 28. The lower inclined portion 40b4 serves as a rotation guide for the ball 31.

[0062] The cam groove 40 fixes the operating rod body 28 at a position where it has moved toward the tip side (upward in this embodiment) when the operating rod body 28 is pushed into the second housing body part 3. The cam groove 40 allows the operating rod body 28 to move toward the base end side (downward in this embodiment) when the operating rod body 28 is pushed again into the second housing body part 3. The tip side direction is the unclamping direction, and the base side direction is the clamping direction.

[0063] The clamping device having the above configuration operates as follows.

[0064] In the clamped state shown in FIG. 1A, the spring 11 as the first biasing means pushes the clamp rod 5 downward (towards the base end), causing the clamp rod 5 to descend. When the clamp rod 5 descends, a push-out portion constituting a part of the retreat groove 17 formed in the clamp rod 5 pushes the ball 15 of the plug portion 4 to a radially outward protruding position. Then, the pressing surface 16 formed in the clamp rod 5 presses the locking portion 25 of the work pallet WP (ring member 23) downward via the ball 15. As a result, the collet 18 contracts in diameter and slightly descends together with the work pallet WP. As a result, the lower surface of the ring member 23 is received by the upper surface 2b (seat surface) of the housing main body 2, and the clamp device is in the clamped state shown in FIG. 1A. At this time, no external force is acting on the ball 36 as the operating member, and the ball 31 is located in the linear groove 40a of the cam groove 40, so that the operating rod main body 28 descends to the lowest limit position. In this embodiment, a gap is formed between the movable member 29 and the ball 6.

[0065] In the clamped state shown in FIG. 1A, for example, the member 50 is used to push the ball 36 upward from below, thereby pushing the operating rod body 28 into the housing second body portion 3 (see FIG. 2A). As a result, the operating rod body 28 first rises straight along the linear groove 40a of the cam groove 40. As the operating rod body 28 rises, the movable member 29 also rises, and the movable member 29 pushes the ball 6 upward (toward the tip side) against the biasing force of the spring 11, and the clamp rod 5 rises. When the clamp rod 5 rises, the retraction groove 17 formed in the clamp rod 5 is positioned to face the ball 15 of the plug portion 4, and the ball 15 can move into the retraction groove 17 (inward in the radial direction of the clamp rod 5). That is, the clamp device is in an unclamped state. At this time, as can be seen from the fact that the flange portion 29a of the movable member 29 is separated downward from the retaining ring 35 in the cylindrical hole 28c, the movable member 29 is in a state of being slightly pushed into the cylindrical hole 28c of the operating rod main body 28 by the reaction force from the ball 6. When the step portion 5c of the clamp rod 5 hits the inner surface of the housing main body 2, or when the tip of the clamp rod 5 hits the bottom surface of the recess 22 of the work pallet WP, the upward movement of the clamp rod 5 is restricted, and as a result, the movable member 29 is in a state of being slightly pushed into the cylindrical hole 28c of the operating rod main body 28 by the reaction force from the ball 6.

[0066] As shown in Fig. 3A, when the operating rod body 28 is further pushed into the housing second body portion 3, the operating rod body 28 rises while rotating in a clockwise direction along the upper inclined portion 40b3 of the rotating groove 40b of the cam groove 40. Thereafter, the ball 31 fits into the upper recessed portion 40b1 (see Fig. 3B), and the rotation of the operating rod body 28 stops. Meanwhile, the clamp rod 5 does not rise any further because its upward movement is restricted. Although the clamp rod 5 does not rise, the operating rod body 28 rises, and the movable member 29 is further pushed into the cylindrical hole 28c of the operating rod body 28 by the reaction force from the ball 6.

[0067] Next, as shown in FIG. 4A, the external force on the ball 36 is released by, for example, moving the member 50 downward. Then, the operating rod body 28 is pushed downward by the biasing force of the spring 30, and the operating rod body 28 descends while rotating in a clockwise direction along the lower inclined portion 40b4 of the rotating groove 40b. After that, the ball 31 fits into the lower recessed portion 40b2 (see FIG. 4B), and the rotation of the operating rod body 28 stops. In this way, the operating rod body 28 is fixed by the cam groove 40 at a position moved toward the tip side from the position in the clamped state shown in FIG. 1A (the downward movement is restricted). Note that the clamp rod 5 does not descend because it is pushed upward by the movable member 29 by the biasing force of the spring 30 via the ball 6 as a power transmission member. Therefore, the unclamped state of the clamp device is maintained even if the external force on the ball 36 is released. Note that at this time, the biasing force of the spring 30 is greater than the biasing force of the spring 11. When the work pallet WP is raised as shown in FIG. 4A, the ring member 23 comes out of the plug portion 4 of the housing 1, and the work pallet WP is detached from the clamp pallet CP.

[0068] When the work pallet WP is to be fixed again to the clamp pallet CP, the external force on the balls 36 is released (see FIG. 4A), and the work pallet WP that has been brought above the clamp device is lowered until the plug portion 4 is inserted into the mounting hole 24 of the ring member 23.

[0069] In this state, as shown in Fig. 5A, the member 50 again pushes the ball 36 upward from below, and the operating rod body 28 is pushed into the housing second body portion 3. Then, the operating rod body 28 rises while rotating in a clockwise direction along the upper inclined portion 40b3 of the rotating groove 40b. Thereafter, the ball 31 fits into the upper recessed portion 40b1 (see Fig. 5B), and the rotation of the operating rod body 28 stops. Note that the clamp rod 5 does not rise because its upward movement is restricted, but the operating rod body 28 rises, and the movable member 29 is pushed further into the cylindrical hole 28c of the operating rod body 28 by the reaction force from the ball 6 than the position shown in Fig. 4A.

[0070] Next, the external force on the ball 36 is released by, for example, moving the member 50 downward. Then, the operating rod body 28 is pushed downward by the biasing force of the spring 30, and the operating rod body 28 descends while rotating in a clockwise direction along the downward inclined portion 40b4 of the rotating groove 40b. After that, the ball 31 enters the linear groove 40a of the rotating groove 40b, and the operating rod body 28 descends straight. The spring 30 is stretched by the descending of the operating rod body 28, and the biasing force of the spring 30 weakens as the operating rod body 28 descends. When the biasing force of the spring 11 as the first biasing means exceeds the biasing force of the spring 30, the clamp rod 5 descends due to the biasing force of the spring 11. When the clamp rod 5 descends, the pushing portion constituting a part of the retraction groove 17 formed in the clamp rod 5 pushes the ball 15 of the plug portion 4 to a protruding position radially outward. Then, the pressing surface 16 formed on the clamp rod 5 presses downward against the locking portion 25 of the work pallet WP (ring member 23) via the ball 15. This causes the collet 18 to contract in diameter and to slightly descend together with the work pallet WP. As a result, the lower surface of the ring member 23 is received on the upper surface 2b (seat surface) of the housing main body 2, and the clamp device enters the clamped state shown in FIG. 1A.

[0071] According to the clamp device of this embodiment, the unclamped state of the clamp device can be maintained without continuously pressing the ball 36 with the member 50, that is, without continuously applying an external force to the ball 36 serving as an operating member.

[0072] In addition, since the operating rod 27 is composed of the operating rod body 28, the movable member 29, and the spring 30 as the second biasing means, the operating rod 27 (operating rod body 28) can be smoothly rotated even in the case of a clamp rod 5 with a short axial movement distance. Since the movable member 29 is adapted to enter the cylindrical hole 28c of the operating rod body 28, the axial movement distance of the operating rod body 28 is longer than the axial movement distance of the clamp rod 5. Therefore, the inclination angle of the upper inclined portion 40b3 and the lower inclined portion 40b4 constituting the turning groove 40b of the cam groove 40 can be made large (easy to ensure) to a degree sufficient for turning the operating rod body 28. By ensuring the inclination angle of the upper inclined portion 40b3 and the lower inclined portion 40b4, the operating rod 27 (operating rod body 28) can be smoothly turned.

[0073] The clamping device of this embodiment further has the following advantages.

[0074] The clamp device does not have a chamber to which pressure fluid is supplied and discharged each time the clamp device is driven, such as the clamp chamber and unclamping chamber of the conventional clamp device described in WO 2021 / 177385. In the clamp device of this embodiment, the ball 36 (operating rod body 28) is moved (pushed upward) by an external force, and the clamp rod 5 is driven in the tip side direction. In the base end direction, which is the opposite direction to the tip side direction, the clamp rod 5 is driven by the spring 11 as the first biasing means. Therefore, the clamp device of this embodiment does not require a pressure fluid such as compressed air for driving.

[0075] Since the spring constant of the spring 30 serving as the second biasing means is greater than the spring constant of the spring 11 serving as the first biasing means, the clamp rod 5 can be reliably moved in the distal end direction. In addition, the clamp rod 5 that has moved in the distal end direction can be reliably held in that position.

[0076] The cam groove 40 has a plurality of linear grooves 40a, and is provided with the same number of protrusions (balls 31) as the linear grooves 40a, and the protrusions (balls 31) are arranged in each linear groove 40a. This configuration can prevent wear and damage to the operating rod 27. Therefore, the operating rod 27 can be operated smoothly.

[0077] By disposing a spherically shaped rotatable power transmission member (ball 6) between the clamp rod 5 and the movable member 29, friction between the clamp rod 5 and the movable member 29 can be reduced, allowing the operating rod 27 (operating rod main body 28) to rotate smoothly.

[0078] Fig. 6 shows a modified example of the clamp device. Fig. 6 is a side cross-sectional view of the clamp device according to the modified example in a clamped state. The tip of the clamp device may have a structure as shown in Fig. 6, instead of the tip of the clamp device shown in Figs. 1A to 5B. The tip of the clamp device shown in Fig. 6 has the following structure.

[0079] A plurality of guide holes 41 are formed at predetermined intervals in the circumferential direction in the peripheral wall of the plug portion 4 of the housing body 2. A locking member 42 (columnar member) serving as a pressing member is inserted into each guide hole 41. The guide holes 41 support each locking member 42 so as to be movable in the radial direction of the clamp rod 5. In this embodiment, the plug portion 4 and the housing body 2 are separate bodies, but the plug portion 4 and the housing body 2 may be integrated.

[0080] The surface of the locking member 42 on the clamp rod 5 side is an inclined surface 42a that approaches the axis of the clamp rod 5 as it extends downward (towards the base end side). In this embodiment, three locking members 42 are inserted into each guide hole 41, but the number of locking members 42 is not limited to three.

[0081] A wedge surface 43 that engages with the inclined surface 42a from the tip side is formed at the tip of the clamp rod 5. Three wedge surfaces 43 are provided corresponding to the number of the locking members 42. In this embodiment, both the wedge surface 43 and the inclined surface 42a are formed of flat surfaces. A thin ring 44 made of an elastic material such as a rubber, resin, or metal spring material is attached to the lower parts of the three locking members 42 and the lower part of the plug part 4. Each locking member 42 is biased radially inward toward the axis of the clamp rod 5 by the elastic force of the ring 44. Note that the means (structure) for moving the locking members 42 radially inward toward the axis of the clamp rod 5 is not limited to the ring 44.

[0082] When the clamp rod 5 descends (moves toward the base end), the locking member 42 is moved radially outward by the wedge surface 43 of the clamp rod 5. As a result, the locking member 42 presses against the inner circumferential surface of the hole 51 of the work pallet WP. This brings the clamp device into a clamped state. When the clamp rod 5 ascends (moves toward the tip end), the elastic force of the ring 44 moves the locking member 42 toward the axial center of the clamp rod 5. This brings the clamp device into an unclamped state.

[0083] Fig. 7 shows a modified example of the clamp device. Fig. 7 is a side cross-sectional view of the modified clamp device in a clamped state. The tip of the clamp device may have a structure as shown in Fig. 7, instead of the tip of the clamp device shown in Figs. 1A to 5B. The tip of the clamp device shown in Fig. 7 has the following structure.

[0084] The tip of the clamp rod 5 is a cap portion 45 having a larger diameter than the remaining portion of the clamp rod 5. An annular groove 46 is formed in the outer circumferential wall of the cap portion 45.

[0085] An outer inclined surface 47 is formed on the outer periphery of the plug portion 4 of the housing body 2 in a tapered shape so as to approach the axis as it approaches the tip side. A cylindrical pressing member 48 is engaged with the outer inclined surface 47. An annular protrusion 48a protrudes radially inward from the upper end of the pressing member 48. The protrusion 48a is fitted into the groove 46 of the cap portion 45, thereby connecting the pressing member 48 to the tip of the clamp rod 5. A slit 48b is provided in the peripheral wall of the pressing member 48, thereby making the pressing member 48 expandable and contractible in the radial direction (elastically deformable). A pin 49 protrudes radially outward from the outer periphery of the plug portion 4 of the housing body 2. The pin 49 prevents the pressing member 48 from rotating.

[0086] When the clamp rod 5 descends (moves toward the base end), the pressing member 48 expands from a reduced diameter state (expands in the radial direction) due to the outer inclined surface 47 of the plug portion 4. As a result, the pressing member 48 presses the inner circumferential surface of the hole 51 of the work pallet WP. This brings the clamp device into a clamped state. When the clamp rod 5 ascends (moves toward the tip end), the pressing member 48 contracts in diameter due to the elastic force of the pressing member 48. This brings the clamp device into an unclamped state.

[0087] The present invention is not limited to the above-described embodiment and its modifications, and various modifications can be made to the above-described embodiment and its modifications without departing from the spirit of the present invention.

[0088] For example, the above embodiment can be modified as follows.

[0089] The ball 36 may be pushed by hand (manually) to move the operating rod body 28 in the distal end direction.

[0090] The pivot groove 40b of the cam groove 40 may be formed so that the operating rod body 28 pivots in a counterclockwise direction instead of a clockwise direction.

[0091] The clamping device may be attached to a table, a tip portion of a robot, etc. The object to be clamped may be a workpiece, a mold, etc.

[0092] Instead of the spring 11 such as a compression coil spring, an air spring may be used. [Explanation of symbols]

[0093] 1: housing, 4: plug portion, 5: clamp rod, 6: ball (power transmission member), 11: spring (first biasing means), 14: through hole, 15: ball (engagement member), 24: mounting hole, 25: locking portion, 27: operating rod, 28: operating rod body, 28a: hole, 28c: cylindrical hole, 29: movable member, 30: spring (second biasing means), 31: ball (sphere, convex portion), 36: ball (operating member), 40: cam groove, 40a: straight groove, 40b: swivel groove, 40b1: upper recessed portion (tip side recessed portion), 40b2: lower recessed portion (base side recessed portion), 40b3: upper inclined portion (tip side inclined portion), 40b4: lower inclined portion (base side inclined portion), WP: work pallet (clamping object)

Claims

1. A housing (1); A clamp rod (5) disposed within the housing (1) so as to be axially movable; an operating rod (27) disposed in series with the clamp rod (5) within the housing (1), the operating rod (27) being rotatable about an axis and pushing and moving the clamp rod (5) toward a tip end side in the axial direction; a first biasing means (11) disposed inside the tip side of the housing (1) and configured to push and move the clamp rod (5) toward the base end side in the axial direction; Equipped with The operating rod (27) is An operating rod body (28) that is rotatable around an axis and has a protrusion (31) on its outer circumferential surface; a movable member (29) disposed in a bottomed cylindrical hole (28c) formed on the tip side of the operating rod body (28), the movable member (29) pushing and moving the clamp rod (5) toward the tip side; and a second biasing means (30) that is extendable and contractible and that is disposed in the cylindrical hole (28c) and biases the movable member (29) toward the tip side relative to the operating rod main body (28), a cam groove (40) in which the convex portion (31) is arranged, the cam groove (40) fixing the operating rod body (28) at a position to which it has moved toward the tip side when the operating rod body (28) is pushed into the housing (1), and allowing the operating rod body (28) to move toward the base end side when the operating rod body (28) is pushed into the housing (1) again, is formed on the inner surface of the housing (1); Clamping device.

2. The clamping device of claim 1, The first biasing means (11) and the second biasing means (30) are both springs, The spring constant of the second biasing means (30) is greater than the spring constant of the first biasing means (11); Clamping device.

3. The clamping device according to claim 1 or 2, The cam groove (40) is A linear groove (40a) extending in the axial direction; a zigzag-shaped swivel groove (40b) extending from the tip of the straight groove (40a) in the circumferential direction of the operating rod body (28), the swivel groove (40b) being for swiveling the operating rod body (28); Clamping device.

4. In the clamping device of claim 3, The turning groove (40b) is a tip-side inclined portion (40b3) inclined with respect to a circumferential direction of the operating rod body (28), the tip-side inclined portion (40b3) being a turning guide for the convex portion (31); a base end side recess (40b2) formed on the base end side of the tip end side inclined portion (40b3), and the protrusion (31) fits into the base end side recess (40b2) to fix the operating rod main body (28). Clamping device.

5. The clamping device of claim 4, The turning groove (40b) is a tip-side recess (40b1) formed in connection with the tip-side inclined portion (40b3), the tip-side recess (40b1) into which the protrusion (31) fits; a base end side inclined portion (40b4) formed between the straight groove (40a) and the base end side recessed portion (40b2) in the circumferential direction of the operating rod body (28), the base end side inclined portion (40b4) serving as a rotation guide for the convex portion 31; Clamping device.

6. In the clamping device of claim 3, The linear grooves (40a) are provided in a plurality at equal intervals in the circumferential direction of the operating rod body (28). Clamping device.

7. The clamping device of claim 6, The convex portions (31) are provided at equal intervals in the circumferential direction of the operating rod body (28), the number of which is the same as the number of the linear grooves (40a). Clamping device.

8. The clamping device according to claim 1 or 2, The convex portion (31) is a rotatable sphere (31), The sphere (31) is disposed in a hole (28a) formed on the outer circumferential surface of the operating rod body (28). Clamping device.

9. The clamping device according to claim 1 or 2, A spherical rotatable operating member (36) is disposed at the base end of the operating rod body (28). Clamping device.

10. The clamping device according to claim 1 or 2, A spherical rotatable power transmission member (6) is disposed between the clamp rod (5) and the movable member (29). Clamping device.

11. The clamping device according to claim 1 or 2, A cylindrical plug portion (4) into which the clamp rod (5) is inserted is provided at the tip of the housing (1), an engaging member (15) that is inserted into a through hole (14) formed in a peripheral wall of the plug portion (4), the engaging member (15) being movable within the through hole (14) as the clamp rod (5) is moved in the axial direction, and capable of coming into contact with a locking portion (25) of a mounting hole (24) provided in a clamping object (WP) so that the plug portion (4) can be inserted; Clamping device.

Images