Clamping Device

Abstract

To provide a clamp device which can be brought into a compact release state.SOLUTION: A piston rod (8) is moved forward or rearward by a piston (3) provided within a housing (1). A movable member (17) which moves relative to the piston rod (8) is connected to the piston rod (8). The movable member (17) is biased upward by an advance spring (13). A clamp arm (24) is rotatably connected to the movable member (17) through a first link member (20). The clamp arm (24) is rotatably connected to the housing (1) through a second link member (22). A connection member (16) is rotatably connected to the second link member (22) through a third link member (23).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a clamping device for fixing an object to be clamped, such as a workpiece, a work pallet, a mold, or a tool, to a table, a movable part of a robot, or the like. [Background technology]

[0002] A conventional clamping device of this type is described in Patent Document 1 (Japanese Patent Laid-Open Publication No. 8-336734). This conventional technology is configured as follows. In the clamping device described above, a piston rod is moved up and down by a piston provided in a housing. A connecting block is fixed to the tip of the piston rod. One end of a first link member is rotatably connected to the connecting block in a vertical plane. Furthermore, one end of a second link member is rotatably connected to a pivot portion provided on the housing in a vertical plane. One end of a third link member is rotatably connected to a longitudinally intermediate portion of the second link member in a vertical plane. The other end of the third link member is rotatably connected to the connecting block in a vertical plane. The other end of the first link member is rotatably connected to a left portion of a clamping arm, and the other end of the second link member is rotatably connected to a longitudinally intermediate portion of the clamping arm. The tip surface of the piston rod can abut against the back surface of the left portion of the clamping arm. When the clamping device is locked and driven to clamp a workpiece, the connecting block is raised via the piston and piston rod by pressurized oil supplied to the clamping device. This upward movement causes the first link member to rotate clockwise relative to the connecting block, and the second link member to rotate clockwise relative to the pivot. This causes the clamp arm to move to the right as it rises. The upper end face of the piston rod engages with the back face of the clamp arm, and the piston rod presses the clamp arm down onto the workpiece, using the connection point between the clamp arm and the second link member as a fulcrum, and secures it on the table. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-336734 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned prior art has the following problems. It is sometimes desirable for the clamping device to be able to secure a workpiece located far away from the clamping device. In this case, the problem can be solved by increasing the length of the clamp arm, each link member, and piston rod. However, increasing the length of each member increases the range of movement of each member. As a result, the clamp arm comes into contact with the piston rod or connecting block while the clamping device is being released, making it impossible to achieve the compact release state of the clamping device. SUMMARY OF THE INVENTION An object of the present invention is to provide a clamping device that can be put into a compact released state. [Means for solving the problem]

[0005] In order to achieve the above object, the present invention provides a clamping device configured as follows, as shown in, for example, FIGS. 1A to 3. A driving mechanism D provided in the housing 1 advances the piston rod 8 toward the distal end and retracts it toward the proximal end. A movable member 17, which is movable axially relative to the piston rod 8, is connected to the piston rod 8. The movable member 17 is urged toward the distal end relative to the housing 1 or the piston rod 8 by a biasing mechanism B. Engagement portions 19a, 30a are formed on the piston rod 8. The engagement portions 19a, 30a face locking portions 18a, 31 formed on the movable member 17 at a predetermined distance toward the distal end and are capable of abutting against the locking portions 18a, 31 from the distal end. A first link member 20 is rotatably connected to the movable member 17. The second link member 22 connected to the housing 1 is rotatable in a plane parallel to the plane in which the first link member 20 rotates. A third link member 23, rotatably connected to the movable member 17, is rotatably connected to the second link member 22. A clamp arm 24, which is rotatably connected to the first link member 20, is rotatably connected to the second link member 22. The clamp arm 24 is capable of contacting the piston rod 8. The clamp arm 24 also has a pressing portion that can contact an object 26 to be clamped.

[0006] The present invention has the following advantages. The clamp device includes a movable member that is biased distally by a biasing mechanism, and the movable member is axially movable relative to the piston rod. Therefore, when switching the clamp device from a locked state to a released state, the piston rod can be lowered before the movable member, leaving the movable member in the distal position. Therefore, when the clamp arm retracts, the piston rod is retracted proximally beyond the movable range of the clamp arm. This prevents interference between the clamp arm and the piston rod, preventing retraction. This allows the piston rod to move the movable member proximally against the biasing force of the biasing mechanism toward the distal end via the engaging portion and the locking portion, while avoiding interference. As a result, the clamp device of this embodiment can be placed in a compact released state.

[0007] The present invention preferably includes the following features (1) and (2). (1) As shown in Figures 1A to 3, a guide portion 19 is formed in the piston rod 8 in a concave shape extending in the axial direction. The engaging portion 19a is formed in the peripheral wall of the tip side of the guide portion 19. A connecting member 18 protruding from the movable member 17 is inserted into the guide portion 19 so as to be movable in the axial direction. The locking portion 18a is formed in the connecting member 18. In this case, while the clamp device is being switched from the locked state to the released state, the piston rod reliably pushes the movable member toward the base end against the biasing force of the biasing mechanism toward the tip end via the engaging portion of the guide portion and the locking portion of the connecting member, thereby moving the clamp arm, movable member, etc. toward the base end so as to approach the housing and in a direction away from the object to be clamped by the piston rod, thereby enabling the clamp device to be compactly placed in the released state.

[0008] (2) As shown in Figures 4A to 6, an engaging member 30 is provided to protrude from the outer peripheral wall of the piston rod 8. An engaging portion 30a is formed on the engaging member 30. A locking portion 31 is formed on the movable member 17. In this case, while the clamp device is being switched from the locked state to the released state, the piston rod reliably pushes the movable member toward the base end against the biasing force of the biasing mechanism toward the tip end via the engaging portion of the engaging member and the locking portion of the movable member, thereby moving the clamp arm, movable member, etc. toward the base end so as to approach the housing and in a direction away from the object to be clamped by the piston rod, thereby enabling the clamp device to be compactly placed in the released state. [Brief explanation of the drawings]

[0009] [Figure 1] Fig. 1A is a cross-sectional side view of a clamp device in a released state according to a first embodiment of the present invention, and Fig. 1B is a plan view of the clamp device. [Figure 2] FIG. 2 is an explanatory diagram of the operation of the clamping device. [Figure 3] FIG. 3 is a cross-sectional view showing the clamp device in a locked state. [Figure 4] Fig. 4A is a cross-sectional side view of a clamp device in a released state according to a second embodiment of the present invention, and Fig. 4B is a plan view of the clamp device. [Figure 5] FIG. 5 is an explanatory diagram of the operation of the clamping device. [Figure 6] FIG. 6 is a cross-sectional view showing the clamp device in a locked state. DETAILED DESCRIPTION OF THE INVENTION

[0010] A first embodiment of the present invention will be described below with reference to FIGS. 1A to 3. FIG. A housing 1 of the clamping device is fixed with bolts to a table T serving as a fixed base. A cylinder bore 2 is formed in the housing 1 in the vertical direction, and a piston 3 is inserted into the cylinder bore 2 so as to be movable up and down (axially) in a hermetically sealed manner. A lock chamber 4 is formed between the piston 3 and a lower wall 1a of the housing 1, and a release chamber 5 is formed between the piston 3 and an upper wall 1b of the housing 1. A supply and discharge path 6 for compressed air (pressurized fluid) is formed in a body 1c of the housing 1, and compressed air from a compressed air supply source (pressurized fluid supply source) is supplied and discharged to the lock chamber 4 through the supply and discharge path 6. Compressed air is also supplied and discharged to the release chamber 5 through another supply and discharge path 7. In the clamping device of this embodiment, a drive mechanism D is configured by the piston 3, the lock chamber 4, the release chamber 5, the supply and discharge paths 6, 7, etc.

[0011] A piston rod 8 projects upward from the piston 3, with the upper portion of the piston rod 8 projecting upward from the upper surface of the housing 1. The piston rod 8 has a large diameter portion 8a and a small diameter portion 8b formed in this order from the base end side. Compressed air supplied to the lock chamber 4 moves the piston rod 8 upward (toward the tip end) via the piston 3, and compressed air supplied to the release chamber 5 moves the piston rod 8 backward (toward the base end) via the piston 3.

[0012] A cylindrical support member 9 is hermetically fitted onto the large diameter portion 8a via a sealing member 10 so as to be able to move along the outer circumferential surface of the piston rod 8. The support member 9 is hermetically inserted into an insertion hole 11 formed in the upper wall 1b of the housing 1 via a sealing member 12. An upper spring retainer 14a (spring retainer 14), an advancing spring 13, and a lower spring retainer 14b (spring retainer 14) are mounted between the upper surface of the piston 3 and the lower surface of the support member 9, and the advancing spring 13 biases the piston 3 and the support member 9 so as to separate them. In the clamp device of this embodiment, a biasing mechanism B is configured by the compression spring serving as the advancing spring 13 and the spring retainer 14.

[0013] A connecting member 15 is integrally formed on the upper part of the support member 9 (or separate members are connected and fixed together). A guide hole 16 is formed in the connecting member 15 in the vertical direction (axial direction), and the small diameter portion 8b of the piston rod 8 is fitted into the guide hole 16. In the clamp device of this embodiment, the support member 9 and the connecting member 15 form a movable member 17. The movable member 17 is guided in the axial direction along the outer circumferential surface of the piston rod 8. Instead of the support member 9 and the connecting member 15 being integrally formed, the support member 9 and the connecting member 15 may be formed as separate members, as in a clamp device of a second embodiment described later. Also, the support member 9 may be omitted and the movable member 17 may be formed only by the connecting member 15.

[0014] An attachment hole perpendicular to the guide hole 16 of the connecting member 15 is formed, and a connecting pin (connecting member) 18 is inserted into the attachment hole. Therefore, the connecting pin 18 protrudes from the inner peripheral surface of the guide hole 16 toward the inside of the guide hole 16. The connecting pin 18 is inserted into an elongated hole (guide portion) 19 formed in the middle of the piston rod 8 in the longitudinal direction and toward the axial direction (up-down direction) of the piston rod 8. Therefore, the connecting pin 18 of the connecting member 15 is guided in the up-down direction along the inner peripheral surface of the elongated hole 19. A locking portion 18a is formed on the upper wall of the connecting pin 18, and an engaging portion 19a is formed on the upper end wall of the elongated hole 19. The engaging portion 19a faces the engaging portion 18a from above with a predetermined gap therebetween and is able to abut against the engaging portion 18a.

[0015] A through hole is formed in the left side wall of the connecting member 15, and a pin is inserted into the through hole. Both ends of the pin protrude from the side wall surface of the connecting member 15. One ends 20a of two first link members 20, which are rotatable in a vertical plane around the end of the pin as a rotational support axis, are connected by the pin so as to sandwich the connecting member 15.

[0016] A pivotal support portion 21 projects upward from the upper portion of the housing 1, and one end portion 22a of two second link members 22 is connected to the pivotal support portion 21 by a pin so as to sandwich the pivotal support portion 21 and be rotatable within a vertical plane.

[0017] One end 23a of a third link member 23 is pin-connected to a longitudinal intermediate portion 22b of the second link member 22 so as to be rotatable within a vertical plane. The other end 23b of the third link member 23 is pin-connected to the connecting member 15 so as to be rotatable within a vertical plane. In the clamp device of this embodiment, both ends of a connecting pin 18 protruding outward from the outer wall surface of the connecting member 15 are used as a rotation support shaft for the other end 23b of the third link member 23. However, this configuration is not limited to this, and a rotation support shaft for the other end 23b may be provided separately from the connecting pin 18.

[0018] The other end 20b of the first link member 20 is rotatably connected by a pin to the left portion 24a of the clamp arm 24. The other end 22c of the second link member 22 is rotatably connected by a pin to the longitudinal intermediate portion 24b of the clamp arm 24 in a vertical plane.

[0019] In the clamp device of the above embodiment, the clamp arm 24, the two first link members 20, the two second link members 22, and the two third link members 23 are rotatable within parallel vertical planes.

[0020] An upper end surface 8c of the piston rod 8 can come into contact with a lower surface 24d of one end 24a of the clamp arm 24. A pressing portion 25 is formed on the lower surface of the other end 24c of the clamp arm 24, and the pressing portion 25 can come into contact with a workpiece 26 as an object to be clamped.

[0021] The clamping device described above, as shown in FIGS. 1A to 3, operates as follows. 1A , compressed air is discharged from lock chamber 4 and supplied to release chamber 5. As a result, the compressed air in release chamber 5 moves piston rod 8 to the lowest position via piston 3. Piston rod 8 pushes movable member 17 to the lowest position via engagement portion 19a of elongated hole 19 and locking portion 18a of connecting pin 18 against the upward biasing force of advancement spring 13 and the upward pressing force of the compressed air in lock chamber 4. As a result, first link member 20, second link member 22, and third link member 23 move clamp arm 24 to the left away from workpiece 26 and retract it in the height direction to an unclamped position, which is lower than the clamped position described below.

[0022] When the clamp device is switched from the release state shown in FIGS. 1A and 1B to the lock state shown in FIG. 3, compressed air is discharged from the release chamber 5 and supplied to the lock chamber 4. A pressing force equivalent to the pressure of the compressed air in the lock chamber 4 moves the piston rod 8 upward via the piston 3. This releases the upward movement restriction on the locking portion 18a of the connecting member 15 by the engaging portion 19a of the piston rod 8, and the biasing force of the advancement spring 13 moves the movable member 17 upward. This causes the first link member 20 to move clockwise relative to the movable member 17. At this time, the movable member 17 presses the second link member 22 via the third link member 23, causing the second link member 22 to move clockwise relative to the pivot portion 21. This causes the first link member 20 and the second link member 22 to move the clamp arm 24 upward and to the right while maintaining the clamp arm 24 in a substantially horizontal position. Subsequently, as shown in FIG. 2, when the clamp arm 24 is moved to the locked position, the pressing portion 25 of the clamp arm 24 comes into contact with the upper surface of the workpiece 26. At this time, the piston 3 presses the workpiece 26 toward the table T via the advancement spring 13, the movable member 17, the first link member 20, the second link member 22, and the clamp arm 24. As a result, the movable member 17, the first link member 20, the second link member 22, and the clamp arm 24 are received by the workpiece 26. Thereafter, the piston 3 and the piston rod 8 are raised, leaving behind the movable member 17 and the like, until the upper end surface 8c of the piston rod 8 comes into contact with the lower surface 24d of the clamp arm 24. As a result, the piston 3 strongly presses the workpiece 26 from above toward the table T via the piston rod 8 and the clamp arm 24. Therefore, the upward movement of the piston 3 and the piston rod 8 is stopped. This switches the clamp device from the released state shown in FIGS. 1A and 1B to the locked state shown in FIG. 3.

[0023] When the clamp device is switched from the locked state shown in FIG. 3 to the released state shown in FIGS. 1A and 1B, compressed air is discharged from the lock chamber 4 and supplied to the release chamber 5. The compressed air in the release chamber 5 then moves the piston rod 8 downward via the piston 3. At this time, the advancing spring 13 presses the clamp arm 24 against the top surface of the workpiece 26 via the movable member 17, the first link member 20, and the second link member 22, maintaining this pressing state. Next, as shown in FIG. 2, the engaging portion 19a of the elongated hole 19 of the piston rod 8 abuts against the locking portion 18a on the connecting pin 18 of the movable member 17. Then, the piston rod 8 moves the movable member 17 downward against the upward biasing force of the advancing spring 13 via the engaging portion 19a and the locking portion 18a of the connecting pin 18. Subsequently, the movable member 17 rotates the first link member 20 counterclockwise relative to the movable member 17. As a result, the movable member 17 rotates the second link member 22 counterclockwise relative to the pivot part 21 via the third link member 23. As a result, the clamp arm 24 moves leftward and rises once, and then moves leftward and falls again. The piston 3 is received by the bottom wall 1a of the housing 1 and stopped. This switches the clamp device from the locked state shown in FIG. 3 to the released state shown in FIGS. 1A and 1B.

[0024] The above embodiment has the following advantages. The clamp device includes a movable member 17 biased upward by an advancing spring 13, and the movable member 17 is movable vertically relative to the piston rod 8. Therefore, when switching the clamp device from a locked state to a released state, the piston rod 8 can be lowered before the movable member 17, with the movable member 17 remaining in the locked position (upper position). Therefore, when the clamp arm 24 retracts, the piston rod 8 is retracted below (toward the base end) the movable range of the clamp arm 8. This prevents interference between the clamp arm 24 and the piston rod 8, preventing the retraction of the clamp arm 24. This prevents such interference from occurring, and allows the piston rod 8 to lower the movable member 17 against the upward biasing force of the advancing spring 13 via the engaging portion 19a of the elongated hole 19 and the locking portion 18a of the connecting pin 18. As a result, the clamp device of this embodiment can be placed in a compact released state.

[0025] 4A to 6 show a second embodiment of the present invention. In this second embodiment, components that are the same as (or similar to) those in the first embodiment will be described with the same reference numerals as in the first embodiment.

[0026] The second embodiment differs from the first embodiment in the following respects. Movable member 17 of the clamping device of this embodiment is composed of a cylindrical support member 9 and a connecting member 15 that is a separate member from support member 9. The upper end surface of support member 9 can abut against the lower surface of connecting member 15. Instead of forming support member 9 and connecting member 15 separately, they may be formed integrally as in the clamping device of the first embodiment. Also, support member 9 may be omitted and movable member 17 may be formed only by connecting member 15.

[0027] In the clamp device of the first embodiment described above, a connecting pin 18 protrudes from the inner peripheral wall of a guide hole 16 of a connecting member 15 into the guide hole 16, and the connecting pin 18 is inserted into an elongated hole 19 of a piston rod 8. In contrast, a clamp device of the second embodiment is provided with a connecting pin 18, but does not protrude from the inner peripheral wall of the guide hole 16 into the guide hole 16. Furthermore, an elongated hole 19 is not provided in the piston rod 8. In the clamp device of this embodiment, an engaging member 30 protrudes from the outer peripheral wall of the piston rod 8, and an engaging portion 30a is formed on the lower wall of the engaging member 30. A locking portion 31 is formed on the upper surface of the connecting member 15 below the engaging portion 30a and facing the engaging portion 30a at a predetermined distance. The engaging portion 30a is engageable with the locking portion 31.

[0028] The procedure for switching the clamp device from the release state of FIGS. 4A and 4B to the lock state of FIG. 6 is substantially the same as that of the clamp device of the first embodiment.

[0029] When the clamp device is switched from the locked state shown in FIG. 6 to the released state shown in FIGS. 4A and 4B, compressed air is discharged from the lock chamber 4 and supplied to the release chamber 5. The compressed air in the release chamber 5 then moves the piston rod 8 downward via the piston 3. At this time, the advancing spring 13 presses the clamp arm 24 against the upper surface of the workpiece 26 via the support member 9, the connecting member 15, the first link member 20, and the second link member 22, maintaining this pressing state. Next, as shown in FIG. 5, the engaging portion 30a of the engaging member 30 of the piston rod 8 abuts against the locking portion 31 of the connecting member 15. Then, the piston rod 8, via the engaging member 30 and the locking portion 31, pushes the connecting member 15 downward against the upward biasing force of the advancing spring 13. The connecting member 15 then rotates the first link member 20, the second link member 22, and the third link member 23 counterclockwise. As a result, the clamp arm 24 is raised once while moving leftward, and then lowered while also moving leftward. The piston 3 is received and stopped by the bottom wall 1a of the housing 1. This switches the clamp device from the locked state shown in Figure 6 to the released state shown in Figures 4A and 4B.

[0030] The clamping device of this embodiment has the following advantages. While the clamp device is being switched from the locked state to the released state, the piston rod 8 pushes the connecting member 15 and the support member 9 downward against the upward biasing force of the advance spring 13 via the engaging portion 30a and the locking portion 31 of the engaging member 30. As a result, the piston rod 8 moves the clamp arm 24, the movable member 17, etc. downward and to the left (in the direction away from the workpiece 26) so as to approach the housing 1, and the clamp device can be compactly set to the released state.

[0031] Furthermore, in the clamp device of this embodiment, the piston rod 8 does not have the elongated hole 19 as in the clamp device of the first embodiment, so that the rigidity of the piston rod 8 can be increased.

[0032] The above embodiments can be modified as follows. The pressure fluid may be other gases or gases such as pressure oil instead of the compressed air exemplified above. The drive mechanism D is a double-acting air cylinder consisting of a piston 3 inserted into a cylinder bore 2 in a housing 1, a lock chamber 4 formed below the piston, and a release chamber 5 formed above the piston. Alternatively, it may be a single-acting air cylinder with a release spring in the release chamber, or a single-acting air cylinder with a lock spring in the lock chamber. Furthermore, it is not limited to an air cylinder, and other drive mechanisms such as a hydraulic cylinder or a motor and a ball screw shaft may also be used. The above-mentioned biasing mechanism B is composed of a compression spring as the advancing spring 13 and a spring bearing 14. However, the invention is not limited to this, and may be configured such that a pressurized fluid (compressed air, other compressed gases, pressure oil, etc.) is sealed in an operating chamber formed below the movable member 17, and the movable member is biased upward (toward the tip) by the pressure of the compressed fluid in the operating chamber. Also, the advancing spring 13 is not limited to being attached between the piston 3 and the movable member 17. Instead of this configuration, the advancing spring 13 (biasing mechanism B) may be attached between the upper wall 1b of the housing 1 and the movable member 17, or may be attached between the outer circumferential wall of the piston rod 8 and the movable member 17. In the clamping device of this embodiment, as shown in Figures 1B and 4B, there are two first link members 20, two second link members 22, and two third link members 23, but this is not limited to this and there may be one or three or more. The concave guide portion may be formed as a groove having a bottom wall and extending in the vertical direction, instead of the long hole 19 that penetrates the piston rod 8 and extends in the vertical direction. Of course, various other modifications can be made within the scope of what can be imagined by those skilled in the art. [Explanation of symbols]

[0033] 1: Housing, 8: Piston rod, 17: Movable member, 18: Connecting member, 18a: Locking portion, 19: Guide portion (long hole), 19a: Engaging portion, 20: First link member, 22: Second link member, 23: Third link member, 24: Clamp arm, 25: Pressing portion, 26: Clamping object (workpiece), 30: Engaging member, 30a: Engaging portion, 31: Locking portion, D: Drive mechanism, B: Biasing mechanism.

Claims

1. a piston rod (8) that is advanced to the distal end side and retracted to the proximal end side by a drive mechanism (D) provided in the housing (1); a movable member (17) connected to the piston rod (8) so as to be movable relative to the piston rod (8) in the axial direction, the movable member (17) being biased by a biasing mechanism (B) toward the tip side relative to the housing (1) or the piston rod (8); an engaging portion (19a, 30a) formed on the piston rod (8), the engaging portion (19a, 30a) facing a locking portion (18a, 31) formed on the movable member (17) at a predetermined interval on the tip side and capable of abutting against the locking portion (18a, 31) from the tip side; a first link member (20) rotatably connected to the movable member (17); a second link member (22) connected to the housing (1) and rotatable in a plane parallel to the plane in which the first link member (20) rotates; a third link member (23) rotatably connected to the movable member (17) and to the second link member (22); a clamp arm (24) that is rotatably connected to the first link member (20) and the second link member (22), the clamp arm (24) being capable of contacting the piston rod (8) and having a pressing portion (25) that is capable of contacting an object to be clamped (26); A clamping device characterized by:

2. The clamping device of claim 1, The piston rod (8) has a guide portion (19) formed in a concave shape extending in the axial direction, The engaging portion (19a) is formed on the peripheral wall of the tip side of the guide portion (19), A connecting member (18) protruding from the movable member (17) is inserted into the guide portion (19) so as to be movable in the axial direction, A clamping device, characterized in that the locking portion (18a) is formed on the connecting member (18).

3. The clamping device of claim 1, An engaging member (30) protrudes from the outer peripheral wall of the piston rod (8), The engaging member (30) is formed with an engaging portion (30a), A clamping device characterized in that a locking portion (31) is formed on the movable member (17).

Images