Clamp device

Abstract

This clamp device is provided with an operating rod (20). A projecting portion (26) is provided on an outer peripheral surface of the operating rod (20). A cam groove (25) in which the projecting portion (26) is disposed is formed in an inner surface of a housing (1) of the clamp device, the cam groove (25) fixing the operating rod (20) at a position to which the operating rod (20) has moved in a tip end side direction when the operating rod (20) is pushed into the housing (1), and allowing the operating rod (20) to move in the base end side direction when the operating rod (20) has again been pushed into the housing (1).

Description

Clamping Device

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

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

[0003] The clamping device (swivel clamp) described in Patent Document 1 includes a clamp rod that is axially movable and rotatable about its axis, a ball for rotating the rod that is inserted into a guide groove formed on the outer periphery of the clamp rod, and a piston for moving the rod forward and backward. The housing that constitutes the swivel clamp is provided with a clamping chamber and an unclamping chamber to which pressure fluid is supplied and discharged. The swivel clamp is driven, i.e., the piston and clamp rod are driven, using, for example, compressed air, and compressed air is supplied to and discharged from the clamping chamber and the unclamping chamber each time the clamp is driven.

[0004] Patent Document 2 discloses a clamping device in which compressed air is supplied to and discharged from a clamping chamber and an unclamping chamber each time the device is driven.

[0005] JP 2018-43324 A International Publication No. 2021 / 177385 A

[0006] When a large number of clamping devices like the one described above are installed, a large-scale compressed air supply system is required. Furthermore, the piping system for supplying and discharging the compressed air is numerous and complex. These are undesirable from the viewpoints of energy conservation and environmental protection. Therefore, it is desirable to eliminate the need for compressed air as a driving source.

[0007] In response to the above, the applicant of the present invention developed a clamping device that does not require a pressurized fluid such as compressed air for driving, and filed patent applications (Japanese Patent Application Nos. 2023-021835 and 2022-152081).

[0008] However, the swivel clamp described in Japanese Patent Application No. 2023-021835 and the clamp device described in Japanese Patent Application No. 2022-152081 have the following problem: In the swivel clamp and clamp device, an external force must be continuously applied to the operating member (e.g., a ball) or the clamp rod to maintain the unclamped state.

[0009] An object of the present invention is to provide a clamping device that can maintain an unclamped state without the need for a continuous application of an external force.

[0010] In order to achieve the above object, the clamping device disclosed in the present application is configured as follows, for example, as shown in FIGS. 1A to 12.

[0011] (1) A clamp device includes a housing 1, a clamp rod 5 arranged within the housing 1 so as to be movable in the axial direction, an operating rod 20 arranged in series with the clamp rod 5 within the housing 1, the operating rod 20 being rotatable about its axis and pushing the clamp rod 5 toward the distal end in the axial direction to move it, a biasing means 16 arranged inside the distal end side of the housing 1 and pushing the clamp rod 5 toward the proximal end in the axial direction to move it, and a convex portion 26 provided on the outer circumferential surface of the operating rod 20. A cam groove 25 in which the convex portion 26 is arranged is formed on the inner surface of the housing 1. The cam groove 25 fixes the operating rod 20 at a position to which it has moved toward the distal end when the operating rod 20 is pushed into the housing 1, and allows the operating rod 20 to move toward the proximal end when the operating rod 20 is pushed into the housing 1 again.

[0012] The clamp device disclosed in this application has the following advantages. The clamp device includes a protrusion provided on the outer peripheral surface of the operating rod, and the cam groove in which the protrusion is disposed. When the operating rod is pushed into the housing, the protrusion and the cam groove fix the operating rod in a position to which it has moved toward the distal end. Because the clamp rod is disposed in series with the operating rod, the clamp rod is also fixed in a position to which it has moved toward the distal end. As a result, the clamp device can maintain an unclamped state without continuously applying an external force to the operating rod. The unclamped state refers to a state in which the clamp rod has moved toward the distal end.

[0013] (2) In the clamping device of (1) above, the cam groove 25 may have a straight groove 25a extending in the axial direction and a zigzag-shaped swivel groove 25b extending from the tip of the straight groove 25a in the circumferential direction of the operating rod 20, the swivel groove 25b being for rotating the operating rod 20.

[0014] With this configuration, the cam groove can be easily formed.

[0015] (3) In the clamp device of (2) above, the swiveling groove 25b may have a tip-side inclined portion 25b3 that is inclined with respect to the circumferential direction of the operating rod 20 and serves as a swiveling guide for the convex portion 26, and a base-side recessed portion 25b2 that is formed on the base end side of the tip-side inclined portion 25b3 and into which the convex portion 26 fits to fix the operating rod 20.

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

[0017] (4) In the clamp device of (3) above, the swivel groove 25b may further include a tip-side recess 25b1 formed in connection with the tip-side inclined portion 25b3, into which the protrusion 26 fits, and a base-side inclined portion 25b4 formed between the straight groove 25a and the base-side recess 25b2 in the circumferential direction of the operating rod 20, which serves as a swivel guide for the protrusion 26.

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

[0019] (5) In any one of the clamp devices (2) to (4) above, the rectilinear grooves 25 a may be provided in plurality at equal intervals in the circumferential direction of the operating rod 20 .

[0020] This configuration reduces the pivot angle of the operating rod per push into the housing, and also makes it easier to form a zigzag-shaped pivot groove, which is part of the cam groove.

[0021] (6) In the clamp device of (5) above, the same number of the protrusions 26 as the number of the rectilinear grooves 25a may be provided at equal intervals in the circumferential direction of the operating rod 20.

[0022] According to this configuration, the force that the protrusion receives can be dispersed, and the movement of the operating rod, including its rotation, can be made smoother.

[0023] (7) In any of the clamping devices (1) to (6) above, the convex portion 26 may be a rotatable sphere 26, and the sphere 26 may be arranged in a hole 20a or a hole 47a formed on the outer peripheral surface of the operating rod 20.

[0024] This configuration can reduce friction between the protrusion and the cam groove, making it possible to make the movement of the operating rod, including its rotation, smoother.

[0025] (8) In any of the clamp devices (1) to (7) above, an operating member 21 is disposed at the base end of the operating rod 20, and the operating member 21 pushes and moves the operating rod 20 toward the tip end, and the operating member 21 may be a rotatable sphere 21.

[0026] With this configuration, the operating rod can be pushed and moved by the operating member provided separately from the operating rod. Also, friction between the operating rod and the operating member can be reduced, allowing smooth movement of the operating rod, including rotation.

[0027] (9) In the clamp device of (8) above, a bearing member 22 for an operating member may be disposed between the base end surface of the operating rod 20 and the operating member 21 .

[0028] This configuration allows the operating rod to be rotated more smoothly.

[0029] (10) In any of the clamp devices (1) to (9) above, a rotatable power transmission member 13 may be disposed between the clamp rod 5 and the operating rod 20.

[0030] This configuration reduces friction between the clamp rod and the operating rod, allowing the operating rod to rotate smoothly.

[0031] (11) In the clamp device of (10) above, the power transmission member 13 may be a sphere 13, and a bearing member 14 for the power transmission member may be arranged between the base end face of the clamp rod 5 and the power transmission member 13.

[0032] This configuration allows the operating rod to be rotated more smoothly.

[0033] (12) In any of the clamp devices (1) to (11) above, the clamp rod 5 may be rotatable about its axis, as shown in, for example, FIGS. 1A to 5B.

[0034] According to this configuration, the clamp device can be a swivel type clamp device in which the clamp rod swivels.

[0035] (13) In any of the clamp devices (1) to (12) above, for example, as shown in FIGS. 6A to 12 , the operating rod 20 may have an operating rod main body 47 that is rotatable around its axis and has the protrusion 26 on its outer peripheral surface, a movable member 48 that is arranged in a bottomed tubular hole 47 c formed on the tip side of the operating rod main body 47 and pushes and moves the clamp rod 5 toward the tip side, and an expandable second biasing means 49 that is arranged in the tubular hole 47 c and biases the movable member 48 toward the tip side relative to the operating rod main body 47.

[0036] According to this configuration, the operating rod is composed of the operating rod body, the movable member, and the second biasing means, so that the operating rod can be rotated smoothly even in the case of a clamp rod with a short axial movement distance.

[0037] (14) In the clamp device of (13) above, the biasing means 16 and the second biasing means 49 may both be springs, and the spring constant of the second biasing means 49 may be greater than the spring constant of the biasing means 16 .

[0038] This configuration allows the clamp rod to be reliably moved in the distal direction, and also allows the clamp rod to be reliably held in position after being moved in the distal direction.

[0039] (15) In any of the clamp devices described in (1) to (14) above, as shown in Figures 6A to 10B, a cylindrical plug portion 29 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 35 inserted into a through hole 34 formed in the peripheral wall of the plug portion 29, the engaging member 35 being moved within the through hole 34 as the clamp rod 5 is moved in the axial direction, and being able to abut against a locking portion 45 of a mounting hole 44 provided in the clamping object WP so that the plug portion 29 can be inserted.

[0040] According to this configuration, the clamping device can be a type of clamping device that clamps the object to be clamped at the mounting hole portion provided in the object to be clamped.

[0041] According to the present invention, it is possible to provide a clamping device that can maintain an unclamped state without continuously applying an external force.

[0042] FIG. 1A is a side cross-sectional view showing a first embodiment of the clamp device when no external force is acting on the operating member and the clamp rod is at its lowest position. FIG. 1B is a development view of the cam groove portion when the clamp device is in the state of FIG. 1A. FIG. 2A is a side cross-sectional view of the clamp device shown in FIG. 1A when the operating member is pushed into the housing. FIG. 2B is a development view of the cam groove portion when the clamp device is in the state of FIG. 2A. FIG. 3A is a side cross-sectional view of the clamp device shown in FIG. 2A when the external force acting on the operating member is released. FIG. 3B is a development view of the cam groove portion when the clamp device is in the state of FIG. 3A. FIG. 4A is a side cross-sectional view of the clamp device shown in FIG. 3A when the operating member is pushed into the housing again. FIG. 4B is a development view of the cam groove portion when the clamp device is in the state of FIG. 4A. FIG. 5A is a side cross-sectional view of the clamp device shown in FIG. 4A when the external force acting on the operating member is released and the work pallet is clamped. Fig. 5B is a development view of the cam groove portion when the clamp device is in the state of Fig. 5A. Fig. 6A is a side cross-sectional view of the clamp device in a clamped state, showing a second embodiment of the clamp device. Fig. 6B is a partial development view of the cam groove portion when the clamp device is in the state of Fig. 6A. Fig. 7A is a side cross-sectional view of the clamp device shown in Fig. 6A when the operating rod body is pushed into the housing. Fig. 7B is a partial development view of the cam groove portion when the clamp device is in the state of Fig. 7A. Fig. 8A is a side cross-sectional view of the clamp device shown in Fig. 7A when the operating rod body is pushed further into the housing. Fig. 8B is a partial development view of the cam groove portion when the clamp device is in the state of Fig. 8A. Fig. 9A is a side cross-sectional view of the clamp device shown in Fig. 8A when the external force acting on the operating member is released and the work pallet WP is raised. Fig. 9B is a partial development view of the cam groove portion when the clamp device is in the state of Fig. 9A.Fig. 10A is a side cross-sectional view of the clamp device shown in Fig. 9A when the work pallet WP is lowered and the operating rod body is pushed into the housing. Fig. 10B is a partial development view of the cam groove portion when the clamp device is in the state of Fig. 10A. Fig. 11 is a side cross-sectional view of the clamp device in the clamped state, showing a modified example of the clamp device of the second embodiment. Fig. 12 is a side cross-sectional view of the clamp device in the clamped state, showing a modified example of the clamp device of the second embodiment.

[0043] (First embodiment) Figures 1A to 5B show a clamping device according to a first embodiment. The configuration of this clamping device will be described first with reference to Figure 1A and other figures. The clamping device secures a work pallet WP, which is an object to be clamped, to a clamping pallet CP, which serves as a base. The clamping device here is a swivel clamp in which the clamp rod 5 swivels about its axis. However, the clamping device is not limited to a swivel clamp. In other words, the clamping device may be one in which the clamp rod 5 does not swivel about its axis, as shown in Figures 6A to 13, for example.

[0044] The clamp device includes a housing 1, a clamp rod 5, and an operating rod 20. The housing 1 is fixed to a clamp pallet CP with a plurality of bolts (not shown). The housing 1 includes a housing main body 2, a support cylinder 3 attached to the inside of the base end of the housing main body 2, and a second housing main body 4 attached to the end face of the base end of the housing main body 2.

[0045] A clamp rod 5 is inserted into a cylindrical hole 2b formed in an upper wall 2a (tip wall) of the housing body 2 so as to be movable in the axial direction (up and down) of the clamp rod 5 and rotatable around the axis of the clamp rod 5. An arm 6 is fixed to the tip of the clamp rod 5 with a bolt 7.

[0046] The clamp rod 5 has, in order from the tip side, a rod main body 5a, a flange portion 5b having a diameter larger than that of the rod main body 5a, and a lower rod portion 5c. The lower rod portion 5c is inserted into the cylindrical hole 3a of the support cylindrical portion 3.

[0047] Three guide grooves 8 are formed at predetermined intervals in the circumferential direction on the outer peripheral surface of the lower rod portion 5c. Only one of the three guide grooves 8 is shown in each of FIGS. 1A, 2A, 3A, 4A, and 5A. Each guide groove 8 is an arcuate groove, consisting of a spiral swivel groove 8a and a linear rectilinear groove 8b. The three swivel grooves 8a are arranged parallel to one another, and the three linear rectilinear grooves 8b are also arranged parallel to one another. The inclination angle of the swivel grooves 8a is set to, for example, 20 to 40 degrees with respect to the radial direction (horizontal direction). Setting the inclination angle of the swivel grooves 8a in this manner shortens the lead of the swivel grooves 8a, thereby reducing the rotation stroke of the clamp rod 5. Note that the number of guide grooves 8 is not limited to three.

[0048] A ball 9 serving as an engaging member is inserted into each of the guide grooves 8. The balls 9 are rotatably supported in support holes 10 formed at predetermined intervals in the circumferential direction on the inner circumferential wall of the cylindrical hole 3a of the support cylindrical portion 3. An annular sleeve 11 is fitted over these three balls 9 so as to be rotatable about its axis. A V-shaped groove 11a is formed on the inner circumferential surface of the sleeve 11, and the balls 9 are able to roll at two points above and below this V-shaped groove 11a.

[0049] The support cylinder 3 is prevented from rotating relative to the housing body 2 by a positioning pin 12. This allows the circumferential position (phase) of the clamp rod 5 relative to the housing body 2 to be adjusted.

[0050] A ball 13 (sphere) serving as a power transmission member is rotatably arranged at the base end of the lower rod portion 5c. The ball 13 is, for example, a metal ball. In this embodiment, a plurality of balls 14 serving as bearing members for the power transmission member are arranged between the base end face of the lower rod portion 5c and the ball 13. The plurality of balls 14 are housed in recesses 15 formed in the base end face of the lower rod portion 5c. The balls 14 are, for example, metal balls. The balls 14 are capable of bearing a load in the axial direction of the clamp rod 5. Because the balls 14 are housed in the recesses 15, they can also bear a portion of a load in a direction perpendicular to the axial direction.

[0051] A spring 16 is disposed in the cylindrical bore space at the tip end of the housing main body 2 as a biasing means for pressing the flange portion 5b of the clamp rod 5 downward (toward the base end). The spring 16 is a compression coil spring. The lower end of the spring 16 is received by a ring-shaped spring bearing 17. A plurality of balls 18 are disposed between the spring bearing 17 and the flange portion 5b as bearing members for the biasing means. The balls 18 are made of metal, for example. The balls 18 can bear the axial load of the clamp rod 5. The spring bearing 17 is restricted from moving in the up and down direction (axial direction) by a retaining ring 19. The spring bearing 17 is not constrained by the clamp rod 5 around the axial direction. In other words, the clamp rod 5 can rotate around its axis relative to the spring bearing 17. The presence of the balls 18 creates a small gap between the bottom surface of the spring bearing 17 and the top surface of the flange portion 5b.

[0052] It should be noted that, instead of a compression coil spring, other types of springs such as a disc spring may be used as the spring 16.

[0053] The operating rod 20 is arranged within the second housing body portion 4 so as to be movable in the axial direction (up and down) of the operating rod 20 and rotatable around the axis of the operating rod 20. The operating rod 20 is arranged in series with the clamp rod 5. The axial direction of the clamp rod 5 and the axial direction of the operating rod 20 are in the same direction. The axis center of the clamp rod 5 and the axis center of the operating rod 20 are the same. The axis center of the clamp rod 5 and the axis center of the operating rod 20 may be slightly misaligned. The ball 13, which serves as a power transmission member, is arranged between the clamp rod 5 and the operating rod 20.

[0054] A ball 21 (sphere) serving as an operating member is rotatably arranged at the base end of the operating rod 20. The ball 21 is, for example, a metal ball. In this embodiment, a plurality of balls 22 serving as bearing members for the operating member are arranged between the base end face of the operating rod 20 and the ball 21. The plurality of balls 22 are housed in recesses 23 formed in the base end face of the operating rod 20. The balls 22 are, for example, metal balls. The balls 22 are capable of bearing a load in the axial direction of the operating rod 20. Because the balls 22 are housed in the recesses 23, they are also capable of bearing a portion of a load in a direction perpendicular to the axial direction.

[0055] The operating member is not limited to the ball 21 (sphere).

[0056] A cylindrical guide member 24 is fixed by screwing to the outer periphery of the base end of the operating rod 20. The end of the guide member 24 is formed to sandwich the ball 21, and the guide member 24 prevents the ball 21 from falling and slides against the ball 21 on the inner circumferential surface of the end. A part of the ball 21 protrudes from the end of the guide member 24.

[0057] A cam groove 25 is formed on the inner surface of the upper portion of the second housing main body portion 4 that constitutes the housing 1. In this embodiment, the cam groove 25 is formed by machining the inner surface of the second housing main body portion 4 and the end surface of the support cylinder portion 3. Figures 1B, 2B, 3B, 4B, and 5B are development views of the cam groove 25 portion.

[0058] The cam groove 25 has a linear groove 25a extending in the axial direction of the operating rod 20 and a zigzag swivel groove 25b extending in the circumferential direction of the operating rod 20. The swivel groove 25b extends from the tip of the linear groove 25a in the circumferential direction of the operating rod 20. The swivel groove 25b is a groove for rotating the operating rod 20.

[0059] The rectilinear grooves 25a are formed in the housing second main body portion 4. A plurality of the rectilinear grooves 25a are provided at predetermined intervals in the circumferential direction of the operating rod 20. Three rectilinear grooves 25a are provided at equal intervals (120-degree intervals in this embodiment) in the circumferential direction of the operating rod 20. Note that the number of rectilinear grooves 25a may be one, two, or four or more.

[0060] As shown in FIG. 1B and other figures, the zigzag-shaped swivel groove 25b has an upper recessed portion 25b1 (tip-side recessed portion) and a lower recessed portion 25b2 (base-side recessed portion). The upper recessed portion 25b1 is formed in the support tube portion 3. A plurality of upper recessed portions 25b1 are provided at predetermined intervals in the circumferential direction of the operating rod 20. Six upper recessed portions 25b1 are provided at equal intervals (60-degree intervals in this embodiment) in the circumferential direction of the operating rod 20. The portions between adjacent upper recessed portions 25b1 are upper inclined portions 25b3 (tip-side inclined portions) that are inclined with respect to the circumferential direction of the operating rod 20. The upper inclined portions 25b3 serve as a swivel guide for the ball 26, which will be described later. The number of upper recessed portions 25b1 may be two, four, eight, or more. The number of upper recessed portions 25b1 is an even number.

[0061] The lower recessed portion 25b2 is formed in the housing second main body portion 4. A plurality of the lower recessed portions 25b2 are provided at predetermined intervals in the circumferential direction of the operating rod 20. Three lower recessed portions 25b2 are provided at equal intervals (120-degree intervals in this embodiment) in the circumferential direction of the operating rod 20. The number of lower recessed portions 25b2 may be one, two, or four or more.

[0062] When a plurality of rectilinear grooves 25a and a plurality of lower recessed portions 25b2 are provided, the rectilinear grooves 25a and the lower recessed portions 25b2 are alternately provided in the circumferential direction of the operating rod 20. The portion between the rectilinear groove 25a and the lower recessed portion 25b2 is a lower inclined portion 25b4 (base end side inclined portion) that is inclined with respect to the circumferential direction of the operating rod 20. The lower inclined portion 25b4 serves as a rotation guide for the ball 26, which will be described later.

[0063] A ball 26 (sphere) serving as a protrusion is disposed in the cam groove 25. The ball 26 is rotatably supported in a hole 20a formed in the outer peripheral surface of the operating rod 20. A plurality of balls 26 and a plurality of holes 20a are provided at predetermined intervals in the circumferential direction of the operating rod 20. Three balls 26 and three holes 20a are provided at equal intervals (120-degree intervals in this embodiment) in the circumferential direction of the operating rod 20. A plurality of balls 26, the same number as the number of rectilinear grooves 25a, are provided at equal intervals in the circumferential direction of the operating rod 20. The number of balls 26 may be one, two, or four or more.

[0064] The protrusions provided on the outer circumferential surface of the operating rod 20 and arranged in the cam groove 25 are not limited to the balls 26. For example, the protrusions may be columnar objects protruding from the side surfaces of the operating rod 20.

[0065] The cam groove 25 fixes the operating rod 20 at a position where it has moved toward the distal end (upward in this embodiment) when the operating rod 20 is pushed into the second housing body 4 via the ball 21. The cam groove 25 allows the operating rod 20 to move toward the proximal end (downward in this embodiment) when the operating rod 20 is pushed into the second housing body 4 again via the ball 21. The distal end direction is the unclamping direction, and the proximal end direction is the clamping direction.

[0066] A spring 27 that pushes the operating rod 20 downward (toward the base end) is disposed in the cylindrical bore space on the base end side of the second housing body portion 4. The spring 27 is a compression coil spring. The lower end of the spring 27 is received by a retaining ring 28 fixed to the side surface of the operating rod 20. The spring constant (elastic force) of the spring 27 is sufficiently smaller than the spring constant (elastic force) of the spring 16. The spring 27 may be omitted.

[0067] The clamping device having the above configuration operates as follows.

[0068] Assume that the clamping device is initially in the state shown in Figure 1A. That is, no external force is acting on the ball 21 serving as the operating member, and the clamp rod 5 is in its lowest position. When no external force is acting on the ball 21, the spring 16 pushes the clamp rod 5 downward (towards the base end) via the spring retainer 17, causing the clamp rod 5 to descend. When there is no object to be clamped, the flange portion 5b of the clamp rod 5 is received on the upper surface of the support cylinder portion 3 (see Figure 1A), and the clamp rod 5 is unable to descend any further and stops. This stop position is the lowest position of the clamp rod 5.

[0069] Assuming the clamp device is in the state shown in FIG. 1A , for example, by pushing the ball 21 upward from below with the member 50 (see FIG. 2A ), the operating rod 20 is pushed into the second housing body portion 4. Then, against the biasing force of the spring 16, the operating rod 20 pushes the clamp rod 5 upward (toward the tip), causing the operating rod 20 and the clamp rod 5 to rise. The operating rod 20 rises straight along the linear groove 25a of the cam groove 25 and then pivots clockwise along the upper inclined portion 25b3 of the pivot groove 25b of the cam groove 25. The ball 26 then fits into the upper recessed portion 25b1 (see FIG. 2B ), stopping the pivoting of the operating rod 20. The clamp rod 5 then rises straight along the linear groove 8b of the guide groove 8 and then pivots counterclockwise along the pivot groove 8a. When the ball 26 fits into the upper recessed portion 25b1, the clamp rod 5 also stops moving upward.

[0070] Next, the external force on the ball 21 is released by, for example, moving the member 50 downward. The operating rod 20 is then pushed downward by the biasing force of the spring 16, and the operating rod 20 rotates clockwise along the downward inclined portion 25b4 of the pivot groove 25b. The ball 26 then fits into the lower recess 25b2 (see FIG. 3B), stopping the rotation of the operating rod 20. In this way, the operating rod 20 is fixed by the cam groove 25 at a position moved toward the distal end from the initial position shown in FIG. 1A (its downward movement is restricted). When the clamp device changes from the state shown in FIG. 2A to the state shown in FIG. 3A, the operating rod 20 and the clamp rod 5 descend, but only slightly. The operating rod 20 and the clamp rod 5 descend by a distance approximately equal to the narrow groove width of the pivot groove 25b.

[0071] 3A is in an unclamped state. According to the clamp device of this embodiment, the unclamped state of the clamp device can be maintained without continuously pressing the ball 21 with the member 50, i.e., without continuously applying an external force to the ball 21 as an operating member.

[0072] Next, it is assumed that the work pallet WP is placed on the clamp pallet CP.

[0073] In this state, the member 50 is again used to push the ball 21 upward from below, forcing the operating rod 20 into the second housing body portion 4. This causes the operating rod 20 to push the clamp rod 5 upward (toward the tip), causing the operating rod 20 to rotate clockwise along the upper inclined portion 25b3 of the swivel groove 25b. The ball 26 then fits into the upper recess 25b1 (see FIG. 4B), stopping the rotation of the operating rod 20. When the clamp device changes from the state of FIG. 3A to the state of FIG. 4A, the operating rod 20 and the clamp rod 5 rise, but only slightly. The operating rod 20 and the clamp rod 5 rise by a distance approximately equal to the narrow groove width of the swivel groove 25b.

[0074] Next, the external force on the ball 21 is released by, for example, moving the member 50 downward. Then, as shown in FIG. 5A, the biasing force of the spring 16 causes the operating rod 20 and the clamp rod 5 to descend from the state shown in FIG. 4A. The operating rod 20 pivots clockwise along the downward inclined portion 25b4 of the swivel groove 25b. Then, as the ball 26 enters the linear groove 25a of the swivel groove 25b, the operating rod 20 descends straight along the linear groove 25a. The clamp rod 5 descends while pivoting clockwise along the swivel groove 8a of the guide groove 8, and then descends straight along the linear groove 8b. The tip of the arm 6 presses the work pallet WP from above. This places the clamp device in a clamped state.

[0075] When switching the clamp device from the clamped state shown in FIG. 5A to the unclamped state shown in FIG. 3A , the member 50 pushes the ball 21 upward from below, thereby pushing the operating rod 20 into the second housing body portion 4. The operating rod 20 then pushes the clamp rod 5 upward (toward the tip), causing the operating rod 20 and the clamp rod 5 to rise. The operating rod 20 rises straight along the linear groove 25a of the cam groove 25 and then pivots clockwise along the upper inclined portion 25b3 of the pivot groove 25b of the cam groove 25. The ball 26 then fits into the upper recess 25b1, stopping the pivoting of the operating rod 20. The clamp rod 5 then rises straight along the linear groove 8b of the guide groove 8 and then pivots counterclockwise along the pivot groove 8a. The ball 26 fits into the upper recess 25b1, stopping the pivoting of the clamp rod 5.

[0076] Next, the external force on the ball 21 is released by, for example, moving the member 50 downward. The operating rod 20 is then pushed downward by the biasing force of the spring 16, and the operating rod 20 rotates clockwise along the downward inclined portion 25b4 of the rotation groove 25b. The ball 26 then fits into the lower recess 25b2 (see FIG. 3B ), stopping the rotation of the operating rod 20. In this way, the operating rod 20 is fixed by the cam groove 25 at a position moved toward the distal end side from the clamped position shown in FIG. 5A (its downward movement is restricted).

[0077] According to the clamping device of this embodiment, the unclamped state of the clamping device can be maintained without continuously pressing the ball 21 with the member 50, that is, without continuously applying an external force to the ball 21 as an operating member.

[0078] The clamping device of this embodiment further has the following advantages.

[0079] The clamping device does not have a chamber into which pressure fluid is supplied or discharged each time the device is driven, such as the clamping chamber and unclamping chamber that are provided in the conventional clamping device described in JP 2018-43324 A. In the clamping device of this embodiment, the ball 21 is moved (pushed upward) by an external force, thereby driving the clamp rod 5 toward the distal end. The clamp rod 5 is driven toward the proximal end, which is the opposite direction from the distal end, by the spring 16. Therefore, the clamping device of this embodiment does not require a pressure fluid, such as compressed air, for driving.

[0080] The cam groove 25 has a plurality of linear grooves 25a, and is provided with the same number of protrusions (balls 26) as the linear grooves 25a, with a protrusion (ball 26) disposed in each linear groove 25a. This configuration allows the force acting on the protrusions (balls 26) to be dispersed, enabling smooth movement of the operating rod 20, including rotation.

[0081] By placing a rotatable power transmission member (ball 13) between the clamp rod 5 and the operating rod 20, friction between the clamp rod 5 and the operating rod 20 can be reduced, allowing the operating rod 20 to rotate smoothly.

[0082] When the clamp rod 5 rotates and ascends, a plurality of balls 18 serving as bearing members for the biasing means, which are disposed between the spring bearing 17 and the flange 5b of the clamp rod 5, roll around the rod main body 5a as the clamp rod 5 rotates. As a result, friction between the balls 18 and the flange 5b is small, allowing the clamp rod 5 to rotate smoothly as it ascends. The same is true when the clamp rod 5 rotates and descends; the rolling of the balls 18 allows the clamp rod 5 to rotate smoothly as it descends.

[0083] Second Embodiment Figures 6A to 10B show a clamping device according to a second embodiment. The configuration of this clamping device will be described first with reference to Figure 6A and other figures. The clamping device secures a work pallet WP, which is an object to be clamped, to a clamping pallet CP, which serves as a base. The clamping device includes a housing 1, a clamp rod 5, and an operating rod 20.

[0084] The housing 1 is fixed to the clamp pallet CP with a plurality of bolts (not shown). The housing 1 is composed of a housing main body 2 and a housing second main body 4 attached to the base end surface of the housing main body 2.

[0085] A cylindrical plug portion 29 protrudes upward integrally from the housing body 2. The plug portion 29 is a part of the housing body 2. The upper rod portion 5d of the clamp rod 5 is inserted into a plug portion cylindrical hole 29a of the plug portion 29 so as to be movable up and down (in the axial direction of the plug portion cylindrical hole 29a). The axial direction of the clamp rod 5 and the axial direction of the plug portion cylindrical hole 29a are the same.

[0086] A cylindrical hole 2c is formed on the base end side of the housing main body 2, and the lower rod portion 5e of the clamp rod 5 is inserted into this cylindrical hole 2c so as to be movable up and down. The cylindrical hole 2c has a larger diameter than the plug portion cylindrical hole 29a. The plug portion cylindrical hole 29a and the cylindrical hole 2c are formed adjacent to each other vertically. The axial direction of the cylindrical hole 2c and the axial direction of the plug portion cylindrical hole 29a are the same.

[0087] A step 5f is provided at the tip end portion of the lower rod portion 5e (the middle portion of the axial direction of the clamp rod 5). This step 5f limits the upward (tip end) movement of the clamp rod 5. When the step 5f hits the inner surface of the housing main body 2, the clamp rod 5 cannot move any further upward.

[0088] A ball 13 (spherical body) serving as a power transmission member is rotatably disposed at the base end of the lower rod portion 5e. The ball 13 is, for example, a metal ball. In this embodiment, the ball 13 is disposed in a recess 15 formed in the base end face of the lower rod portion 5e. The ball 13 is prevented from coming out of the recess 15 by a retaining ring 30 (a ring-shaped stopper). The retaining ring 30 is attached to the inner circumferential surface of the recess 15. A portion of the ball 13 protrudes outward in the axial direction of the clamp rod 5 from the end face of the lower rod portion 5e. In addition, a plurality of balls 14 serving as bearing members for the power transmission member are disposed between the bottom surface of the recess 15 and the ball 13. The balls 14 are, for example, metal balls. The balls 14 are capable of bearing a load in the axial direction of the clamp rod 5. Because the balls 14 are housed in the recess 15, they can also bear a portion of a load perpendicular to the axial direction.

[0089] The base end of the lower rod portion 5e, where the recess 15 is formed, is a piston portion 31 (large diameter portion), which has a larger diameter than the other portions of the clamp rod 5. A spring 16 is disposed in the space above the piston portion 31 in the cylindrical bore 2c, as a biasing means for pushing the piston portion 31 downward (toward the base end). The spring 16 is a compression coil spring. In this embodiment, the spring 16 is composed of a first spring 16a and a second spring 16b. The diameter of the second spring 16b is larger than the diameter of the first spring 16a. A first step portion 31a that receives the lower end of the first spring 16a and a second step portion 31b that receives the lower end of the second spring 16b are provided on the upper surface (tip side surface) of the piston portion 31, in this order from the inside. A ring-shaped spring support 32 is provided on the first spring 16a to receive the upper end of the first spring 16a, and a ring-shaped spring support 33 is provided on the second spring 16b to receive the upper end of the second spring 16b.

[0090] The spring 16 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.

[0091] A plurality of through holes 34 are formed at predetermined intervals in the circumferential direction in an upper portion of the peripheral wall of the plug portion 29. A ball 35 (engagement ball) serving as an engagement member is inserted into each through hole 34. Each ball 35 is supported by the through hole 34 so as to be movable between a radially inward position (inner position) shown in Fig. 7A and a radially outward position (outer position) shown in Fig. 6A.

[0092] Pressing surfaces 36 and retraction grooves 37 are formed in a vertical line on the outer peripheral wall of the upper rod portion 5d of the clamp rod 5, corresponding to each ball 35. The pressing surfaces 36 are formed to widen upward. When the pressing surfaces 36 move to a position facing the balls 35, the balls 35 are moved to an outer position so as to protrude radially outward from the outer peripheral surface of the plug portion 29. When the retraction grooves 37 move to a retracted position facing the balls 35 and allowing the balls 35 to be inserted, the balls 35 can move radially inward from the outer peripheral surface of the plug portion 29. In this embodiment, four balls 35 are inserted into each of the through holes 34, but the number of balls 35 is not limited to four.

[0093] An annular collet 38 is fitted onto the lower portion (root portion) of the peripheral wall of the plug portion 29. The collet 38 has a tapered outer peripheral surface 38a that tapers upward and is elastically reduced in diameter by a single slit 38b extending in the vertical direction. The collet 38 is prevented from coming out of the plug portion 29 (upward movement is restricted) by a retaining ring 39. A plurality of through holes 41 are formed at predetermined intervals in the circumferential direction on the upper surface 2d of the housing main body 2, into which a pressing member 40 is inserted to press the collet 38 upward (toward the tip side). The pressing member 40 is cylindrical and has a large-diameter portion 40a (flange portion) at its lower end. At the large-diameter portion 40a, the pressing member 40 is supported from below by the spring retainer 32. The collet 38 is biased upward by the first spring 16a via the pressing member 40 and the spring retainer 32. Therefore, the collet 38, whose upward movement is restricted by the retaining ring 39, can move slightly in the vertical direction. In this embodiment, three pressing members 40 are inserted into the through holes 41, one for each, but the number of pressing members 40 is not limited to three.

[0094] A recess 42 is opened in the underside of the work pallet WP. A ring member 43 is attached to the recess 42, and the ring member 43 is fixed to the work pallet WP with a plurality of bolts (not shown). An attachment hole 44 is formed by an inner peripheral hole of the ring member 43, and the plug portion 29 can be inserted into the attachment hole 44.

[0095] A locking portion 45 is formed in a tapered shape so as to widen as it extends upward in the mounting hole 44 of the ring member 43. A tapered inner peripheral surface 46 that engages with the tapered outer peripheral surface 38a of the collet 38 is formed below the locking portion 45. The tapered inner peripheral surface 46 is tapered upward, in other words, a surface that narrows as it extends upward.

[0096] In this embodiment, the mounting hole 44 is formed in the ring member 43, but the mounting hole 44 may be formed by the inner peripheral hole of the recess 42 of the work pallet WP. In other words, the locking portion 45 and the tapered inner peripheral surface 46 may be formed in the inner peripheral hole itself of the recess 42 of the work pallet WP.

[0097] An operating rod 20 is disposed within the second housing body portion 4 so as to be movable in the axial direction (up and down) and rotatable about its axis. The operating rod 20 is disposed in series with the clamp rod 5. The operating rod 20 is composed of an operating rod body 47, a movable member 48, and a spring 49 serving as second biasing means. The spring 49 is a compression coil spring. The axial direction of the clamp rod 5 and the axial direction of the operating rod body 47 are the same.

[0098] The operating rod main body 47 is cylindrical, and has holes 47a formed in the upper portion of its outer circumferential surface, in which balls 26 (spheres) are disposed as protrusions. The balls 26 are rotatably supported by the holes 47a. A plurality of balls 26 and a plurality of holes 47a are provided at predetermined intervals in the circumferential direction of the operating rod main body 47. Four balls 26 and four holes 47a are provided at equal intervals (90-degree intervals in this embodiment) in the circumferential direction of the operating rod main body 47. A plurality of balls 26, the number of which is the same as the number of linear grooves 25a of the cam grooves 25 described below, are provided at equal intervals in the circumferential direction of the operating rod main body 47. The number of balls 26 is not limited to four. Furthermore, the protrusions provided on the outer circumferential surface of the operating rod main body 47 are not limited to balls 26. For example, the protrusions may be columnar objects integral with the operating rod main body 47 that protrude from the outer circumferential surface of the operating rod main body 47.

[0099] A spring 51 that pushes the operating rod main body 47 downward (toward the base end) is arranged on the outside of the lower portion of the operating rod main body 47. The spring 51 is a compression coil spring. The upper end of the spring 51 is received by the housing second main body portion 4. The lower end of the spring 51 is received by a ring-shaped spring receiver 52. A plurality of balls 53 are arranged between the spring receiver 52 and the flange portion 47b at the lower end of the operating rod main body 47. The balls 53 are, for example, metal balls. Due to the presence of the rotatable balls 53, the spring receiver 52 is not constrained by the operating rod main body 47 around the axial direction. Therefore, the operating rod main body 47 is rotatable around the axis relative to the spring receiver 52.

[0100] The spring constant of spring 51 is sufficiently smaller (negligibly small) than the spring constants of both spring 16 and spring 49. Spring 51 is merely for suppressing rattle of operating rod main body 47 and may be omitted. Note that, since spring 16 is made up of two springs, the spring constant of spring 16 is the sum of the spring constants of the two springs (first spring 16a and second spring 16b).

[0101] A bottomed cylindrical hole 47c is formed at the tip end of the operating rod main body 47, and a cylindrical movable member 48 and an expandable spring 49 (second biasing means) are disposed in this cylindrical hole 47c. The upper end of the spring 49 is received by a flange portion 48a (large diameter portion) of the movable member 48. The lower end of the spring 49 is received by the bottom surface of the cylindrical hole 47c. The spring 49 biases the movable member 48 upward (toward the tip end) relative to the operating rod main body 47. The biasing force of the spring 49 causes the movable member 48 to push and move the clamp rod 5 upward (toward the tip end) via the ball 13. A concave surface 48b into which the ball 13 fits is formed on the tip surface of the movable member 48. A retaining ring 54 (ring-shaped stopper) prevents the movable member 48 from slipping out of the cylindrical hole 47c. The retaining ring 54 is attached to the upper portion of the inner circumferential surface of the cylindrical hole 47c. A ventilation hole 47d is provided in the bottom surface of the cylindrical hole 47c. When the movable member 48 descends within the cylindrical hole 47c, air is discharged through the ventilation hole 47d. Conversely, when the movable member 48 ascends, outside air flows into the cylindrical hole 47c through the ventilation hole 47d.

[0102] In this embodiment, the spring constant of the spring 49 is set to be larger than the spring constant of the spring 16. Note that other types of springs, such as disc springs, may be used instead of compression coil springs as the spring 49. The spring constant of the spring 49 may be the same as or smaller than the spring constant of the spring 16.

[0103] A ball 21 (spherical body) serving as an operating member is rotatably arranged at the base end of the operating rod main body 47. The ball 21 is, for example, a metal ball. In this embodiment, the ball 21 is arranged in a recess 55 formed in the base end face of the operating rod main body 47. The ball 21 is prevented from coming out of the recess 55 by a retaining ring 56 (a ring-shaped stopper). A portion of the ball 21 protrudes outward from the operating rod main body 47 in the axial direction of the operating rod main body 47. In addition, a plurality of balls 22 serving as bearing members for the operating member are arranged between the bottom surface of the recess 55 and the ball 21. The balls 22 are, for example, metal balls. The balls 22 are capable of bearing a load in the axial direction of the operating rod 20. Because the balls 22 are housed in the recess 55, they are also capable of bearing a portion of a load in a direction perpendicular to the axial direction.

[0104] The operating member is not limited to the ball 21 (sphere).

[0105] A cam groove 25 in which a ball 26 is disposed is formed on the inner surface of the second housing body portion 4 that constitutes the housing 1. In this embodiment, the cam groove 25 is formed by machining the inner surface of the second housing body portion 4 and machining the end surface of the housing body portion 2. Figures 6B, 7B, 8B, 9B, and 10B are partial development views of the cam groove 25 portion.

[0106] The cam groove 25 has a linear groove 25a extending in the axial direction of the operating rod body 47 and a zigzag swivel groove 25b extending in the circumferential direction of the operating rod body 47. The swivel groove 25b extends from the tip of the linear groove 25a in the circumferential direction of the operating rod body 47 and is formed so as to zigzag up and down (in the axial direction of the operating rod body 47). The swivel groove 25b is a groove for rotating the operating rod body 47.

[0107] The rectilinear grooves 25a are formed in the housing second main body portion 4. A plurality of the rectilinear grooves 25a are provided at predetermined intervals in the circumferential direction of the operating rod main body 47. Four rectilinear grooves 25a are provided at equal intervals (90-degree intervals in this embodiment) in the circumferential direction of the operating rod main body 47. The number of the rectilinear grooves 25a is not limited to four.

[0108] As shown in FIG. 6B and other figures, the zigzag-shaped swivel groove 25b has an upper recessed portion 25b1 (tip-side recessed portion) and a lower recessed portion 25b2 (base-side recessed portion). The upper recessed portion 25b1 is formed in the housing main body 2. A plurality of upper recessed portions 25b1 are provided at predetermined intervals in the circumferential direction of the operating rod main body 47. Eight upper recessed portions 25b1 are provided at equal intervals (45-degree intervals in this embodiment) in the circumferential direction of the operating rod main body 47. The portions between adjacent upper recessed portions 25b1 are upper inclined portions 25b3 (tip-side inclined portions) that are inclined with respect to the circumferential direction of the operating rod main body 47. The upper inclined portions 25b3 serve as a swivel guide for the ball 26. The number of upper recessed portions 25b1 is not limited to eight. The number of upper recessed portions 25b1 is an even number.

[0109] The lower recessed portions 25b2 are formed in the housing second main body portion 4. A plurality of the lower recessed portions 25b2 are provided at predetermined intervals in the circumferential direction of the operating rod main body 47. Four lower recessed portions 25b2 are provided at equal intervals (90-degree intervals in this embodiment) in the circumferential direction of the operating rod main body 47. The number of lower recessed portions 25b2 is not limited to four.

[0110] When a plurality of rectilinear grooves 25a and a plurality of lower recessed portions 25b2 are provided, the rectilinear grooves 25a and the lower recessed portions 25b2 are provided alternately in the circumferential direction of the operating rod body 47. The portion between the rectilinear groove 25a and the lower recessed portion 25b2 is a lower inclined portion 25b4 (base end side inclined portion) that is inclined with respect to the circumferential direction of the operating rod body 47. The lower inclined portion 25b4 serves as a rotation guide for the ball 26.

[0111] The cam groove 25 fixes the operating rod body 47 at a position where it has moved toward the distal end (upward in this embodiment) when the operating rod body 47 is pushed into the second housing body 4. When the operating rod body 47 is pushed again into the second housing body 4, the cam groove 25 allows the operating rod body 47 to move toward the proximal end (downward in this embodiment). The distal end direction is the unclamping direction, and the proximal end direction is the clamping direction.

[0112] The clamping device having the above configuration operates as follows.

[0113] In the clamped state shown in FIG. 6A , the spring 16 as a biasing means pushes the clamp rod 5 downward (toward the base end), causing the clamp rod 5 to descend. As the clamp rod 5 descends, a push-out portion constituting a part of the retraction groove 37 formed in the clamp rod 5 pushes the ball 35 of the plug portion 29 radially outward to a protruding position. Then, the pressing surface 36 formed on the clamp rod 5 presses the locking portion 45 of the work pallet WP (ring member 43) downward via the ball 35. This causes the collet 38 to contract in diameter and slightly descend together with the work pallet WP. As a result, the lower surface of the ring member 43 is received by the upper surface 2d (seat surface) of the housing main body 2, and the clamp device enters the clamped state shown in FIG. 6A . At this time, no external force is acting on the ball 21 as the operating member, and the ball 26 is positioned in the rectilinear groove 25a of the cam groove 25, so the operating rod main body 47 descends to its lowest position. In this embodiment, a gap is formed between the movable member 48 and the ball 13 .

[0114] In the clamped state shown in FIG. 6A , for example, by pushing the ball 21 upward from below with a member 50, the operating rod body 47 is pushed into the second housing body portion 4 (see FIG. 7A ). This causes the operating rod body 47 to first rise straight along the linear groove 25a of the cam groove 25. As the operating rod body 47 rises, the movable member 48 also rises, and the movable member 48 pushes the ball 13 upward (toward the tip) against the biasing force of the spring 16, causing the clamp rod 5 to rise. When the clamp rod 5 rises, the retraction groove 37 formed in the clamp rod 5 is positioned facing the ball 35 of the plug portion 29, allowing the ball 35 to move into the retraction groove 37 (inward in the radial direction of the clamp rod 5). In other words, the clamp device is in an unclamped state. At this time, as can be seen from the fact that the flange portion 48a of the movable member 48 is separated downward from the retaining ring 54 in the cylindrical hole 47c, the movable member 48 is in a state of being slightly pushed into the cylindrical hole 47c of the operating rod main body 47 by the reaction force from the ball 13. When the stepped portion 5f 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 42 of the work pallet WP, the upward movement of the clamp rod 5 is restricted, and as a result, the movable member 48 is in a state of being slightly pushed into the cylindrical hole 47c of the operating rod main body 47 by the reaction force from the ball 13.

[0115] As shown in Figure 8A, when the operating rod body 47 is further pushed into the second housing body portion 4, the operating rod body 47 rises while rotating clockwise along the upper inclined portion 25b3 of the rotation groove 25b of the cam groove 25. Thereafter, the ball 26 fits into the upper recessed portion 25b1 (see Figure 8B), stopping the rotation of the operating rod body 47. 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 47 rises, and therefore the movable member 48 is further pushed into the tubular hole 47c of the operating rod body 47 by the reaction force from the ball 13.

[0116] Next, as shown in FIG. 9A , the external force on the ball 21 is released, for example, by moving the member 50 downward. The operating rod body 47 is then pushed downward by the biasing force of the spring 49, and the operating rod body 47 descends while rotating clockwise along the downward inclined portion 25 b 4 of the rotation groove 25 b. The ball 26 then fits into the lower recess 25 b 2 (see FIG. 9B ), stopping the rotation of the operating rod body 47. In this way, the operating rod body 47 is fixed by the cam groove 25 at a position further toward the distal end than the clamped position shown in FIG. 6A (its downward movement is restricted). The clamp rod 5 does not descend because it is being pushed upward by the movable member 48 by the biasing force of the spring 49 via the ball 13 serving as a power transmission member. Therefore, the unclamped state of the clamp device is maintained even when the external force on the ball 21 is released. At this time, the biasing force of the spring 49 is greater than the biasing force of the spring 16. As shown in FIG. 9A, when the work pallet WP is raised, the ring member 43 comes out of the plug portion 29 of the housing 1, and the work pallet WP is detached from the clamp pallet CP.

[0117] When the work pallet WP is to be fixed to the clamp pallet CP again, the external force on the balls 21 is released (see Figure 9A), and the work pallet WP that has been brought above the clamp device is lowered so that the plug portion 29 is inserted into the mounting hole 44 of the ring member 43.

[0118] In this state, as shown in Figure 10A, the member 50 is again used to push the ball 21 upward from below, forcing the operating rod body 47 into the second housing body portion 4. This causes the operating rod body 47 to rise while rotating clockwise along the upper inclined portion 25b3 of the rotating groove 25b. Thereafter, the ball 26 fits into the upper recessed portion 25b1 (see Figure 10B), thereby stopping the rotation of the operating rod body 47. Note that the clamp rod 5 does not rise because its upward movement is restricted, but the operating rod body 47 does rise, and therefore the movable member 48 is pushed further into the tubular hole 47c of the operating rod body 47 by the reaction force from the ball 13 than the position shown in Figure 9A.

[0119] Next, the external force on the ball 21 is released, for example, by moving the member 50 downward. The spring 49 then pushes the operating rod body 47 downward, causing it to descend while rotating clockwise along the downward inclined portion 25b4 of the swivel groove 25b. The ball 26 then enters the linear groove 25a of the swivel groove 25b, causing the operating rod body 47 to descend straight. The downward movement of the operating rod body 47 stretches the spring 49, and the biasing force of the spring 49 weakens as the operating rod body 47 descends. When the biasing force of the spring 16, which serves as a biasing means, exceeds the biasing force of the spring 49, the clamp rod 5 descends due to the biasing force of the spring 16. As the clamp rod 5 descends, a push-out portion constituting a part of the retraction groove 37 formed in the clamp rod 5 pushes the ball 35 of the plug portion 29 radially outward to a protruding position. Then, the pressing surface 36 formed on the clamp rod 5 presses downward against the locking portion 45 of the work pallet WP (ring member 43) via the ball 35. This causes the collet 38 to contract in diameter and slightly descend together with the work pallet WP. As a result, the lower surface of the ring member 43 is received by the upper surface 2d (seat surface) of the housing main body 2, and the clamp device enters the clamped state shown in FIG. 6A.

[0120] According to the clamping device of this embodiment, the unclamped state of the clamping device can be maintained without continuously pressing the ball 21 with the member 50, that is, without continuously applying an external force to the ball 21 as an operating member.

[0121] Furthermore, because the operating rod 20 is composed of the operating rod main body 47, the movable member 48, and the spring 49 as the second biasing means, the operating rod 20 (operating rod main body 47) can be smoothly rotated even in the case of a clamp rod 5 with a short axial movement distance. Because the movable member 48 fits into the tubular bore 47c of the operating rod main body 47, the axial movement distance of the operating rod main body 47 is longer than the axial movement distance of the clamp rod 5. Therefore, the inclination angles of the upper inclined portion 25b3 and the lower inclined portion 25b4 constituting the rotation groove 25b of the cam groove 25 can be (easily ensured) large enough to allow the operating rod main body 47 to rotate. By ensuring the inclination angles of the upper inclined portion 25b3 and the lower inclined portion 25b4, the operating rod 20 (operating rod main body 47) can be smoothly rotated.

[0122] The clamping device of this embodiment further has the following advantages.

[0123] The clamping device does not have a chamber into which pressure fluid is supplied and discharged each time the device is driven, such as the clamping chamber and unclamping chamber provided in the conventional clamping device described in WO 2021 / 177385. In the clamping device of this embodiment, the ball 21 (operating rod body 47) is moved (pushed upward) by an external force, thereby driving the clamp rod 5 toward the distal end. The clamp rod 5 is driven toward the proximal end, which is the opposite direction from the distal end, by a spring 16 serving as a biasing means. Therefore, the clamping device of this embodiment does not require a pressure fluid such as compressed air for driving.

[0124] The spring constant of the spring 49 serving as the second biasing means is set to be greater than the spring constant of the spring 16 serving as the biasing means, so that the clamp rod 5 can be reliably moved in the distal direction. In addition, the clamp rod 5 that has moved in the distal direction can be reliably held in that position.

[0125] The cam groove 25 has a plurality of linear grooves 25a, and is provided with the same number of protrusions (balls 26) as the linear grooves 25a, with a protrusion (ball 26) disposed in each linear groove 25a. This configuration can prevent wear and damage to the operating rod 20. Therefore, the operating rod 20 can be operated smoothly.

[0126] By placing a spherical rotatable power transmission member (ball 13) between the clamp rod 5 and the movable member 48, friction between the clamp rod 5 and the movable member 48 can be reduced, allowing the operating rod 20 (operating rod main body 47) to rotate smoothly.

[0127] Fig. 11 shows a modified example of the clamp device of the second embodiment. Fig. 11 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. 11 instead of the tip of the clamp device shown in Figs. 6A to 10B. The tip of the clamp device shown in Fig. 11 has the following structure.

[0128] A plurality of guide holes 57 are formed at predetermined intervals in the circumferential wall of the plug portion 29 of the housing main body 2. A locking member 58 (a columnar member) serving as a pressing member is inserted into each guide hole 57. The guide holes 57 support each locking member 58 so that it can move radially of the clamp rod 5. In this embodiment, the plug portion 29 and the housing main body 2 are separate bodies, but the plug portion 29 and the housing main body 2 may also be integrated.

[0129] The surface of the locking member 58 facing the clamp rod 5 is an inclined surface 58a that approaches the axis of the clamp rod 5 as it extends downward (towards the base end). In this embodiment, three locking members 58 are inserted into the guide holes 57, one each, but the number of locking members 58 is not limited to three.

[0130] A wedge surface 59 that engages with the inclined surface 58a from the tip side is formed at the tip of the clamp rod 5. Three wedge surfaces 59 are provided, corresponding to the number of locking members 58. In this embodiment, both the wedge surfaces 59 and the inclined surfaces 58a are flat surfaces. Thin rings 60 made of an elastic material such as rubber, resin, or metal spring material are attached to the lower parts of the three locking members 58 and the lower part of the plug portion 29. The elastic force of the rings 60 urges each locking member 58 radially inward toward the axial center of the clamp rod 5. Note that the means (structure) for moving the locking members 58 radially inward toward the axial center of the clamp rod 5 is not limited to the rings 60.

[0131] When the clamp rod 5 descends (moves toward the base end), the wedge surface 59 of the clamp rod 5 moves the locking member 58 radially outward. As a result, the locking member 58 presses against the inner circumferential surface of the hole 61 in the work pallet WP. This places the clamp device in a clamped state. When the clamp rod 5 ascends (moves toward the tip end), the elastic force of the ring 60 moves the locking member 58 toward the axial center of the clamp rod 5. This places the clamp device in an unclamped state.

[0132] Fig. 12 shows a modified example of the clamp device of the second embodiment. Fig. 12 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. 12 instead of the tip of the clamp device shown in Figs. 6A to 10B. The tip of the clamp device shown in Fig. 12 has the following structure.

[0133] The tip of the clamp rod 5 is formed as a cap portion 62 having a larger diameter than the remaining portion of the clamp rod 5. An annular groove 63 is formed in the outer peripheral wall of the cap portion 62.

[0134] An outer inclined surface 64 is formed on the outer periphery of the plug portion 29 of the housing main body 2, tapering toward the axis as it approaches the tip. A cylindrical pressing member 65 is engaged with the outer inclined surface 64. An annular protrusion 65a protrudes radially inward from the upper end of the pressing member 65. The protrusion 65a is fitted into a groove 63 of the cap portion 62, connecting the pressing member 65 to the tip of the clamp rod 5. A slit 65b is formed in the peripheral wall of the pressing member 65, allowing the pressing member 65 to expand and contract in the radial direction (elastically deformable). A pin 66 protrudes radially outward from the outer periphery of the plug portion 29 of the housing main body 2. The pin 66 prevents the pressing member 65 from rotating.

[0135] When the clamp rod 5 descends (moves toward the base end), the pressing member 65 expands from its reduced diameter state (expands radially) due to the outer inclined surface 64 of the plug portion 29. As a result, the pressing member 65 presses the inner circumferential surface of the hole 61 of the work pallet WP. This puts the clamp device in a clamped state. When the clamp rod 5 ascends (moves toward the tip end), the pressing member 65 contracts in diameter due to its own elastic force. This puts the clamp device in an unclamped state.

[0136] 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 invention.

[0137] For example, the above embodiment can be modified as follows.

[0138] The ball 21 serving as an operating member may be manually pushed to move the operating rod 20 toward the distal end. Alternatively, an external force may be applied directly to the operating rod 20 to move the operating rod 20 without providing an operating member such as the ball 21.

[0139] The turning groove 25b of the cam groove 25 may be formed so that the operating rod 20 turns counterclockwise instead of clockwise.

[0140] An air spring may be used instead of the spring 16 such as a compression coil spring.

[0141] The clamping device may be attached to a table, the tip of a robot, etc. The object to be clamped may be a workpiece, a mold, etc.

[0142] 1: Housing, 5: Clamp rod, 13: Ball (spherical body, power transmission member), 14: Ball (bearing member for power transmission member), 16: Spring (biasing means), 20: Operating rod, 20a: Hole, 21: Ball (spherical body, operating member), 22: Ball (bearing member for operating member), 25: Cam groove, 25a: Straight groove, 25b: Swivel groove, 25b1: Upper recessed portion (tip-side recessed portion), 25b2: Lower recessed portion (base-side recessed portion), 25b3: Upper inclined portion (tip-side inclined portion), 25b4: Lower inclined portion (base-side inclined portion), 26: Ball (spherical body, convex portion), 29: Plug portion, 34: Through hole, 35: Ball (engaging member), 44: Mounting hole, 45: Locking portion, 47: Operating rod main body, 47a: Hole, 47c: Cylindrical hole, 48: Movable member, 49: Spring (second biasing means)

Claims

1. A housing (1); a clamp rod (5) arranged within the housing (1) so as to be movable in the axial direction; an operating rod (20) arranged within the housing (1) in series with the clamp rod (5), the operating rod (20) being rotatable about its axis and pushing and moving the clamp rod (5) in the axial direction toward the tip end; a biasing means (16) arranged inside the tip side of the housing (1) and pushing and moving the clamp rod (5) in the axial direction toward the base end; and a protrusion (26) provided on the outer circumferential surface of the operating rod (20); A cam groove (25) in which the convex portion (26) is arranged is formed on the inner surface of the housing (1), the cam groove (25) fixing the operating rod (20) at a position to which it has moved toward the tip side when the operating rod (20) is pushed into the housing (1), and allowing the operating rod (20) to move toward the base end side when the operating rod (20) is pushed into the housing (1) again.

2. A clamp device according to claim 1, wherein the cam groove (25) has a straight groove (25a) extending in the axial direction, and a zigzag-shaped rotating groove (25b) extending from the tip of the straight groove (25a) in the circumferential direction of the operating rod (20), the rotating groove (25b) for rotating the operating rod (20).

3. A clamp device according to claim 2, wherein the swivel groove (25b) has a tip-side inclined portion (25b3) inclined relative to the circumferential direction of the operating rod (20), the tip-side inclined portion (25b3) serving as a swivel guide for the convex portion (26), and a base-side recessed portion (25b2) formed on the base end side of the tip-side inclined portion (25b3), into which the convex portion (26) fits to fix the operating rod (20).

4. A clamp device according to claim 3, wherein the swivel groove (25b) further comprises: a tip-side recess (25b1) formed adjacent to the tip-side inclined portion (25b3), into which the protrusion (26) fits; and a base-side inclined portion (25b4) formed between the straight groove (25a) and the base-side recess (25b2) in the circumferential direction of the operating rod (20), the base-side inclined portion (25b4) serving as a swivel guide for the protrusion (26).

5. A clamp device according to any one of claims 2 to 4, wherein the linear grooves (25a) are provided in a plurality at equal intervals in the circumferential direction of the operating rod (20).

6. A clamp device according to claim 5, wherein a plurality of said protrusions (26) equal in number to the number of said linear grooves (25a) are provided at equal intervals in the circumferential direction of said operating rod (20).

7. A clamp device according to any one of claims 1 to 6, wherein the convex portion (26) is a rotatable sphere (26), and the sphere (26) is disposed in a hole (20a, 47a) formed in the outer circumferential surface of the operating rod (20).

8. A clamp device according to any one of claims 1 to 7, further comprising an operating member (21) disposed at the base end of the operating rod (20) for pushing and moving the operating rod (20) in the tip end direction, the operating member (21) being a rotatable sphere (21).

9. The clamp device according to claim 8, wherein a bearing member (22) for an operating member is disposed between the base end face of the operating rod (20) and the operating member (21).

10. The clamp device according to any one of claims 1 to 9, wherein a rotatable power transmission member (13) is disposed between the clamp rod (5) and the operating rod (20).

11. A clamp device according to claim 10, wherein the power transmission member (13) is a sphere (13), and a bearing member (14) for the power transmission member is disposed between the base end face of the clamp rod (5) and the power transmission member (13).

12. The clamping device according to any one of claims 1 to 11, wherein the clamp rod (5) is rotatable about an axis.

13. A clamp device according to any one of claims 1 to 12, wherein the operating rod (20) comprises: an operating rod body (47) rotatable about its axis and having the protrusion (26) on its outer peripheral surface; a movable member (48) arranged in a bottomed cylindrical hole (47c) formed on the tip side of the operating rod body (47), the movable member (48) pushing and moving the clamp rod (5) in the tip side direction; and a second biasing means (49) arranged in the cylindrical hole (47c) and extendable and urging the movable member (48) in the tip side direction relative to the operating rod body (47).

14. A clamp device according to claim 13, wherein the biasing means (16) and the second biasing means (49) are both springs, and the spring constant of the second biasing means (49) is greater than the spring constant of the biasing means (16).

15. A clamp device according to any one of claims 1 to 14, comprising: a cylindrical plug portion (29) into which the clamp rod (5) is inserted, provided at the tip of the housing (1); and an engaging member (35) inserted into a through hole (34) formed in the peripheral wall of the plug portion (29), the engaging member (35) being movable within the through hole (34) as the clamp rod (5) is moved in the axial direction, and capable of abutting against a locking portion (45) of a mounting hole (44) provided in an object to be clamped (WP) so that the plug portion (29) can be inserted.

Images