JP7485283B2 - Clamping Device - Google Patents

Description

This invention relates to a clamping device for fixing a workpiece, tool, etc. to a fixed table, robot, etc.

A conventional clamping device of this type is described in Patent Document 1 (International Publication No. WO 2012/073723). This conventional technology is configured as follows.
A cylindrical cap member is inserted into a space formed in the housing so as to be movable in the vertical and horizontal directions, and an upper portion of the cap member protrudes upward from the upper wall of the housing. The cap member is insertable into a hole in an object to be clamped. A clamp rod is inserted into the cylindrical hole of the cap member so as to be slidable along the cylindrical hole. As the clamp rod is moved up and down, an engaging member that presses the object to be clamped is moved horizontally. The clamp rod is pin-connected to a piston rod that is inserted into the housing so as to be movable up and down, so as to be movable horizontally.

International Publication No. 2012/073723

In the above-mentioned conventional technology, even if the axis of the cap member and the axis of the hole of the clamp object are misaligned in the horizontal direction, when the cap member is inserted into the clamp object, the clamp object pushes the clamp rod horizontally through the cap member to move it within the movable range so that the axis of the clamp rod approaches the axis of the hole of the clamp object. Therefore, the clamp device is excellent in that the clamp object can be reliably clamped in a state where the axis of the cap member and the axis of the clamp object are almost aligned. However, when the cap member is inserted into the hole of the clamp object that is misaligned beyond the movable range of the clamp rod and the cap member, and the clamp object is moved horizontally to be within the movable range of the cap member, a strong horizontal pressing force of the clamp object acts on the cap member and the clamp rod. In this case, since a sliding gap is formed between the cap member and the space in the housing, the cap member is tilted by the pressing force by the dimension of the sliding gap. Therefore, there is room for improvement in that the clamp object into which the tilted cap member is inserted may be fixed in a position or state that is different from the desired position or state.
An object of the present invention is to provide a clamping device that can reliably fix an object to be clamped within a predetermined range of position.

In order to achieve the above object, the present invention provides a clamp device configured as follows, for example, as shown in FIGS. 1A to 18.
A cylindrical cap member 3, 37 protrudes toward the tip side from the tip wall of the housing 1. The cap member 3, 37 is insertable into a hole 5 of an object to be clamped 4. An output member 9 is movably inserted within the housing 1. A clamp rod 17 is inserted into a cylindrical hole 8, 36 of the cap member 3, 37 so as to be movable in the axial and radial directions, and the clamp rod 17 is connected to the output member 9 so as to be movable in the radial direction of the output member 9. An engagement member 22 is inserted into a guide hole 24 penetrating the cylindrical wall of the cap member 3, 37, and the engagement member 22 is moved along the guide hole 24 by the clamp rod 17.

The present invention provides the following advantageous effects.
When the cap member is inserted into the hole of the clamping object, the clamping object is moved by the cap member to a position within a predetermined range in the horizontal direction relative to the clamping device. In addition, since the clamp rod is movable in the horizontal direction relative to the output member, the axis of the clamp rod is moved to approach the axis of the hole in the workpiece during locking. As a result, with the cap member receiving the force of the clamping object pushing in the horizontal direction, the clamping device can reliably press and clamp the clamping object at a position where the axis of the clamp rod is approximately aligned with the axis of the hole in the clamping object.

The present invention preferably includes the following configurations (1) to (8).
(1) For example, as shown in Figs. 1A to 3B, 4 and 5, an insertion hole 16 is formed at the tip of the output member 9, and the clamp rod 17 is inserted into the insertion hole 16. A positioning portion 28 is provided to protrude radially outward from the outer circumferential wall of the clamp rod 17. A relief portion 30 is formed on the outer circumferential wall of the clamp rod 17 at a location separate from the positioning portion 28. A reference portion 31 is formed on the inner circumferential wall of the insertion hole 16. The clamp rod 17 is connected to the output member 9 so as to be movable horizontally and axially relative to the output member 9. When the clamp rod 17 is moved axially relative to the output member 9 and the positioning portion 28 faces or abuts against the reference portion 31, the radial movement of the clamp rod 17 is restricted. When the clamp rod 17 is moved axially relative to the output member 9 and the relief portion 30 faces the reference portion 31, the clamp rod 17 is movable radially.
In this case, when the clamp device is driven to lock and the relief portion faces the reference portion, the clamp rod is movable horizontally relative to the output member. Also, when the clamp device is driven to release and the positioning portion faces the reference portion, the predetermined position (e.g., axis) of the clamp rod is moved in a direction that coincides with the predetermined position (e.g., axis) of the cap member. Therefore, when the workpiece is attached to and detached from the cap member, the workpiece can be prevented from coming into contact with the engaging member and becoming worn, or from colliding with and being damaged.

(2) For example, as shown in Figures 1A to 3B, a long hole 19 is radially inserted through the clamp rod 17 so as to be elongated in the axial direction. A connecting pin 20 is provided on the peripheral wall of the insertion hole 16 and protrudes toward the inside of the insertion hole 16. The connecting pin 20 is inserted into the long hole 19.
In this case, the connecting pin can move relative to the long hole along the axial direction of the clamp rod and the penetrating direction of the long hole.

(3) For example, as shown in Fig. 4, a hole 19A is formed radially through the peripheral wall of the insertion hole 16. A connecting pin 20A protrudes radially outward from the clamp rod 17, and the connecting pin 20A is inserted into the hole 19A.
In this case, the connecting pin can move relative to the long hole in the axial direction of the clamp rod and in a direction intersecting the axial direction.

(4) For example, as shown in Fig. 5, a long hole 19B is radially inserted into the peripheral wall of the insertion hole 16 so as to be elongated in the axial direction. A connecting pin 20B protrudes radially outward from the clamp rod 17, and the connecting pin 20B is inserted into the long hole 19B so as to be movable axially and radially relative to the clamp rod 17.
In this case, the connecting pin can move relative to the long hole along the axial direction of the clamp rod and the penetrating direction of the long hole.

(5) For example, as shown in Figures 6 to 18, a positioning portion 47 protrudes radially outward from the outer peripheral wall of the clamp rod 17. A relief portion 49 is formed on the outer peripheral wall of the clamp rod 17 at a location separate from the positioning portion 47. A reference portion 50 is formed on the inner peripheral wall of the cylindrical hole 36 of the cap member 37. When the clamp rod 17 is moved axially and the positioning portion 47 faces the reference portion 50, the radial movement of the clamp rod 17 is restricted. When the clamp rod 17 is moved axially and the relief portion 49 faces the reference portion 31, the clamp rod 17 is able to move radially.

(6) For example, as shown in Figures 6 to 10, 15 and 16, an annular stopper 46 is attached to the tip wall of the housing 1 so as to be movable in the radial direction, and the outer surface of the engaging member 22 can abut against the inner circumferential wall of the stopper 46.
In this case, after the clamp rod moves the engaging member radially outward of the clamp rod and abuts against the stopper, the clamp rod and the engaging member move together in the axial direction of the clamp rod, and the stopper reliably limits the radial outward movement of the engaging member relative to the clamp rod.

(7) For example, as shown in FIGS. 11 and 12, a stopper 56 is provided to protrude outward from the clamp rod 17 and faces the tip surface of the engaging member 22 with a predetermined gap therebetween so as to be able to come into contact with the tip surface of the engaging member 22.
In this case, after the clamp rod moves the engaging member outward in the radial direction of the clamp rod and the stopper abuts against the engaging member, the clamp rod and the engaging member move together in the axial direction of the clamp rod, and the stopper reliably limits the radial outward movement of the engaging member relative to the clamp rod.

13 and 14, for example, a long hole 57 is formed in the cylindrical wall of the cap member 37 so as to extend radially and axially. An end of a connecting pin 20C that connects the output member 9 and the clamp rod 17 is inserted into the long hole 57 so as to be movable along the long hole 57.
In this case, when the clamp rod is moved axially a predetermined distance to move the engaging member radially of the clamp rod, the connecting pin abuts against the end of the long hole in the cap member. This causes the clamp rod to move the engaging member axially via the cap member. As a result, after the abutment, the engaging member is reliably restricted from moving radially outward relative to the clamp rod.

Fig. 1A is a schematic cross-sectional view showing a first embodiment of the present invention, and Fig. 1B is a partial cross-sectional view taken along line 1B-1B in Fig. 1A. Fig. 2A is a cross-sectional view showing the clamp device in a released state, and is a view similar to Fig. 1. Fig. 2B is a partial cross-sectional view taken along line 2B-2B in Fig. 2A. Fig. 3A is a cross-sectional view showing the clamp device in a locked state, and is a view similar to Fig. 1. Fig. 3B is a partial cross-sectional view taken along line 3B-3B in Fig. 3A. FIG. 4 shows a first modification of the first embodiment, and is a partial cross-sectional view similar to FIG. 1B. FIG. 5 shows a second modified example of the first embodiment, and is a cross-sectional view similar to FIG. 1A. FIG. 6 is a schematic cross-sectional view showing a second embodiment of the present invention. Fig. 7A is a cross-sectional view showing the clamp device in a released state, and is a partial view similar to Fig. 6. Fig. 7B is a partial cross-sectional view taken along line 7B-7B in Fig. 7A. FIG. 8 is an explanatory view of the operation of the clamp device, and is a view similar to FIG. FIG. 9 is an explanatory view of the operation of the clamp device, and is a view similar to FIG. FIG. 10 is a cross-sectional view showing the clamp device in a locked state, and is a view similar to FIG. FIG. 11 shows a first modified example of the second embodiment, and is a cross-sectional view showing a released state of the clamp device. FIG. 12 is a cross-sectional view similar to FIG. 11, showing the clamp device in a locked state. FIG. 13 shows a second modified example of the second embodiment, and is a cross-sectional view showing the clamp device in a released state. FIG. 14 is a cross-sectional view similar to FIG. 13, showing the clamp device in a locked state. FIG. 15 shows a third modified example of the second embodiment, and is a cross-sectional view showing the clamp device in a released state. FIG. 16 is a cross-sectional view similar to FIG. 15, showing the clamp device in a locked state. FIG. 17 shows a fourth modified example of the second embodiment, and is a cross-sectional view showing the clamp device in a released state. FIG. 18 is a cross-sectional view similar to FIG. 17, showing the clamp device in a locked state.

A first embodiment of the present invention will be described below with reference to FIGS. 1A to 3B.
In this embodiment, the clamp device is applied to a hole clamp.

The housing 1 is fixed by bolts to a table T as a fixed base. A cylindrical cap member 3 protrudes upward from the housing body 2 so as to be integral with the housing body 2. The cap member 3 can be inserted into a hole 5 in a workpiece (object to be clamped) 4. In this embodiment, the outer diameter of the cap member 3 is set smaller than the inner diameter of the hole 5 in the workpiece 4. A cylinder hole 7 is formed in the housing 1 in the vertical direction, and the cylinder hole 7 is connected to a cylindrical hole 8 in the cap member 3. An output member 9 is inserted into the cylinder hole 7 so as to be movable in the vertical direction (axial direction of the cylinder hole 7). The output member 9 has a piston 9a inserted into the cylinder hole 7 and a piston rod 9b protruding upward from the upper surface of the piston 9a.

A lock chamber 11 is formed above the piston 9a, and a release chamber 12 is formed below the piston 9a. A retaining spring 13 is attached inside the lock chamber 11 and biases the piston 9a downward. In addition, pressure oil from a pressure oil source is supplied to and discharged from the lock chamber 11 through a lock supply/discharge passage 14 formed inside the housing 1, and is supplied to and discharged from the release chamber 12 through a release supply/discharge passage 15.

An insertion hole 16 is formed in the upper end (tip end) of the piston rod 9b in the vertical direction (axial direction), and the lower end (base end) 18 of the clamp rod 17 is inserted into the insertion hole 16 with a gap in the horizontal direction. The clamp rod 17 is connected to the piston rod 9b by a pin so that it can move horizontally. In this embodiment, a connecting pin 20 protrudes radially inward from the cylindrical wall of the piston rod 9b. The connecting pin 20 is inserted into a long hole 19 that penetrates the clamp rod 17 so that it can move horizontally and vertically. Therefore, the clamp rod 17 can move horizontally along the connecting pin 20 relative to the piston rod 9b, and can move vertically along the long hole 19.

Three wedge portions 21 are formed on the outer peripheral wall of the clamp rod 17 at a predetermined interval in the circumferential direction so that they widen (the diameter dimension increases) toward the tip side. The receiving portion 23 of the engagement member 22 abuts against each wedge portion 21. A dovetail groove 21a is provided along the inclined surface of the wedge portion 21, and a guide rail 23a formed on the receiving portion 23 is inserted into the dovetail groove 21a. The engagement member 22 is movably inserted into a guide hole 24 formed in the cylindrical wall of the cap member 3. In this embodiment, the engagement member 22 is inserted into the ceiling and bottom of the inner peripheral wall of the guide hole 24 with a sliding gap between the upper and lower surfaces of the engagement member 22, and the engagement member 22 is inserted between the side surface of the inner peripheral wall of the guide hole 24 and the side surface of the engagement member 22 with a gap larger than the sliding gap. A pressing portion 25 is formed on the outer wall of the engagement member 22, and the pressing portion 25 can abut against the inner peripheral surface of the hole 5 of the workpiece 4. Here, in the clamp device of this embodiment, instead of providing three engaging members 22a, 22b, and 22c at a predetermined interval on the outer peripheral wall of the clamp rod 17, two engaging members 22a and 22b may be provided.

The hole clamp of this embodiment is equipped with a return mechanism R that moves the clamp rod 17 so that the axis of the clamp rod 17 coincides with the axis of the piston rod 9b when the clamp rod 17 is released. The return mechanism R is provided between the outer peripheral wall of the clamp rod 17 and the inner peripheral wall of the insertion hole 16 of the piston rod 9b, and is configured as follows.

A positioning portion 28 is continuously protruded from the outer peripheral surface of the lower end of the clamp rod 17 in the horizontal direction (diameter direction of the clamp rod 17). A tapered portion 29 and an escape portion 30 are formed in sequence below the positioning portion 28. A reference portion 31 is also formed on the inner peripheral wall of the insertion hole 16 of the piston rod 9b. When the piston rod 9b is moved upward relative to the clamp rod 17 and the positioning portion 28 faces the reference portion 31, the horizontal movement of the clamp rod 17 is restricted. When the piston rod 9b is moved downward relative to the clamp rod 17 and the escape portion 30 faces the reference portion 31, the horizontal movement of the clamp rod 17 is permitted. The return mechanism R of this embodiment is composed of the positioning portion 28, the tapered portion 29, the escape portion 30, and the reference portion 31. In this embodiment, the positioning portion 28 is configured to protrude continuously in the circumferential direction from the outer peripheral surface of the clamp rod 17 in the horizontal direction, but this is not limited to this, and it may be divided into two or three or more parts at a predetermined interval in the circumferential direction. Similarly, in this embodiment, the reference portion 31 is configured to protrude continuously in the circumferential direction from the inner peripheral surface of the piston rod 9b, but this is not limited to this, and it may be divided into two or three or more parts at a predetermined interval in the circumferential direction.

The Hall clamp, as shown in Figures 1A to 3B, operates as follows.
In the initial state (release state) of Fig. 1A and Fig. 1B, pressure oil is discharged from the lock chamber 11 and pressure oil is supplied to the release chamber 12. Therefore, the pressing force of the pressure oil in the release chamber 12 moves the piston 9a to the upper limit position against the biasing force of the holding spring 13. Therefore, the piston 9a moves the clamp rod 17 to the upper limit position via the piston rod 9b. Therefore, the clamp rod 17 moves the engaging member 22 radially inward via the dovetail groove 21a and the guide rail 23a. At this time, the positioning portion 28 of the clamp rod 17 faces the reference portion 31 of the piston rod 9b, and the horizontal movement of the clamp rod 17 relative to the piston rod 9b is limited. In addition, the axis of the clamp rod 17 is approximately aligned with the axis of the piston rod 9b. Therefore, the engaging member 22 is accommodated in the cap member 3 so that its outer surface is located inside the outer circumferential surface of the cap member 3. This prevents the peripheral wall of the hole 5 in the work 4 from colliding with the engaging member 22 when the cap member 3 is fitted onto the hole 5 in the work 4. As a result, wear and damage to the engaging member 22 and the work 4 due to the collision is prevented.

The workpiece 4 is moved above the hole clamp in the released state. At this time, the axis of the hole 5 of the workpiece 4 is horizontally displaced by a distance A from the axis of the cylinder hole 7 of the hole clamp. When the workpiece 4 is lowered, the peripheral wall of the hole 5 of the workpiece 4 abuts against the tapered portion 3a of the cap member 3 of the hole clamp. After that, the workpiece 4 is lowered while moving rightward along the tapered portion 3a of the cap member 3. Then, as shown in FIG. 2A, the hole 5 of the workpiece 4 fits the cap member 3 from the outside. At this time, the axis of the hole 5 of the workpiece 4 is horizontally displaced by a distance B from the axis of the cylinder hole 7 of the hole clamp. Here, in this embodiment, the axis distance A is a distance that exceeds the allowable positional deviation tolerance range, and the axis distance B is a distance that is within the allowable positional deviation tolerance range. In other words, by fitting the hole 5 of the workpiece 4 to the cap member 3, the cap member 3 moves the workpiece 4 from outside the positional deviation tolerance range into the positional deviation tolerance range.

When the hole clamp is driven to lock from the release state of FIG. 2A and FIG. 2B to the lock state of FIG. 3A and FIG. 3B, pressure oil is discharged from the release chamber 12 and pressure oil is supplied to the lock chamber 11. Then, the pressing force of the pressure oil in the lock chamber 11 and the urging force of the holding spring 13 move the clamp rod 17 downward via the piston 9a and the piston rod 9b, and the clamp rod 17 moves the engaging member 22 radially outward of the clamp rod 17. At this time, the positioning portion 28 of the clamp rod 17 is pulled out of the insertion hole 16 of the piston rod 9b, and the tapered portion 29 or the relief portion 30 faces the reference portion 31. Therefore, the clamp rod 17 can move horizontally relative to the cap member 3. Next, in FIG. 2A and FIG. 2B, the pressing portion 25 of the engaging members 22b, 22c on the right side of the axis of the clamp rod 17 is received by the inner wall of the hole 5 of the workpiece 4. After that, the clamp rod 17 is lowered and moved leftward. During this time, the clamp rod 17 pushes the engaging member 22a, which is on the left side of the axis of the clamp rod 17, to the left. Then, the pressing portion 25 of the left engaging member 22a abuts against the inner peripheral surface of the hole 5 of the workpiece 4. At this time, the axis of the workpiece 4 is horizontally shifted by a distance B from the axis of the cylinder hole 7 of the housing 1, but the axis of the clamp rod 17 and the axis of the hole 5 of the workpiece 4 are aligned. As a result, the three engaging members 22a, 22b, and 22c press evenly against the inner peripheral wall of the hole 5 of the workpiece 4. As a result, the hole clamp is switched from the released state of FIG. 2A to the locked state of FIG. 3A.

When the hole clamp is released from the locked state of FIG. 3A to the released state of FIG. 2A, pressure oil is discharged from the lock chamber 11 and supplied to the release chamber 12. Then, the pressing force of the pressure oil in the release chamber 12 moves the piston 9a upward against the biasing force of the retaining spring 13. When the piston 9a moves the clamp rod 17 upward via the piston rod 9b, the clamp rod 17 moves the three engaging members 22a, 22b, 22c radially inward of the clamp rod 17. Then, when the tapered surface 29 of the clamp rod 17 abuts against the peripheral wall of the cylindrical tip of the piston rod 9b, the clamp rod 17 and the three engaging members 22a, 22b, 22c are moved to the right so that the axis of the clamp rod 17 coincides with the axis of the housing 1. Then, the positioning surface 28 of the clamp rod 17 faces the reference surface 31, and the horizontal movement of the clamp rod 17 relative to the piston rod 17 is restricted. The piston 9a is then received and stopped by the upper wall of the housing 1. As a result, the hole clamp is switched from the locked state of FIG. 3A to the released state of FIG. 2A.

The above embodiment has the following advantages.
When the hole 5 of the workpiece 4 is fitted onto the cap member 3, the cap member 3 moves the workpiece 4 from a position outside the allowable range to a position within the allowable range (desired position). At this time, the workpiece 4 exerts a force pressing the cap member 3 horizontally (to the left in the figure), but since the cap member 3 is integrally formed with the housing body 2, the cap member 3 does not tilt. Therefore, even if the workpiece 4 is misaligned, it is seated at a position within a predetermined range. In addition, since the clamp rod 17 is horizontally movable relative to the output member 9, the axis of the clamp rod 17 is moved to approach the axis of the hole 5 of the workpiece 4 during lock drive. As a result, the engaging member 22 presses the inner peripheral wall of the hole 5 of the workpiece 4 evenly, so that the clamp device can clamp the workpiece 4 reliably.

When switching from the locked state to the released state, the tapered surface 29 abuts against the reference portion 31, moving the axis of the clamp rod 17 closer to the axis of the housing 1, and the positioning portion 28 faces the reference portion 31, so that the axis of the clamp rod 17 and the axis of the housing 1 are approximately aligned. This allows the engaging member 22 to be stored in the cap member 3 in the released state. As a result, when a workpiece is attached to or removed from the cap member 3, the engaging member 22 can be prevented from being worn or damaged by the peripheral wall of the hole 5 in the workpiece 4.

The positions and shapes of the connecting pin 20, the long hole 19, etc. of the clamp device of the first embodiment may be as shown in the first and second modified examples of the first embodiment shown in Figures 4 and 5.

In the first modified example of the first embodiment shown in FIG. 4, the long hole 19 of the first embodiment is changed to a circular hole 19A. That is, the clamp rod 17 is passed through the circular hole 19A, which is set to have a diameter larger than the diameter of the connecting pin 20A, and the connecting pin 20A is inserted into the hole 19A with a gap larger than the sliding gap. This allows the clamp rod 17 to move vertically and horizontally relative to the piston rod 9b. The shape of the hole 19A in this modified example is not limited to a circle, and may be an ellipse or an approximately polygonal shape, etc.

In a second modified example of the first embodiment shown in FIG. 5, a long hole 19B is inserted into the cylindrical wall of the cylindrical tip of the piston rod 9b so that it is longer in the vertical direction. A connecting pin 20B protrudes from the outer peripheral surface of the lower end 18 of the clamp rod 17 in the radial direction of the clamp rod 17, and the connecting pin 20B is inserted into the long hole 19B so that it can slide vertically. The shape of the hole 19B in this modified example is not limited to the long hole shown as an example, and may be circular, elliptical, or approximately polygonal.

Figures 6 to 10 show a second embodiment of the present invention. In this second embodiment, components that are the same as (or similar to) the components of the first embodiment described above are generally given the same reference numerals.

The second embodiment differs from the above-described first embodiment in the following respects.
A support cylinder 35 is provided on the upper part of the housing 1 to protrude. A cylindrical cap member 37 is inserted into the cylindrical hole 36 so as to be movable in the vertical direction (axial direction of the cylindrical hole 36). The cap member 37 has a large diameter portion 38 that is inserted into the cylindrical hole 36 of the support cylinder 35, and a small diameter portion 39 that protrudes above the large diameter portion 38. The small diameter portion 39 can be inserted into the hole 5 of the workpiece 4. A cylindrical hole is formed from the inside of the large diameter portion 38 to the inside of the small diameter portion 39, and a part of the piston rod 9b and the clamp rod 17 are inserted into the cylindrical hole so as to be movable in the vertical direction. An attachment groove 40 is formed in the outer peripheral wall of the large diameter portion 38 in the circumferential direction, and an elastic ring 41 is attached to the attachment groove 40. The elastic ring 41 is a ring-shaped elastic member formed of metal, and is a substantially C-shaped member having a slit 42 formed in the peripheral wall. When the elastic ring 41 is inserted into the locking groove 43 formed in the inner circumferential wall of the cylindrical hole 36 of the support tube 35, the elastic ring 41 expands in diameter due to its elastic restoring force, and engages with a step portion 44 formed between the locking groove 43 and the inner circumferential surface of the cylindrical hole 36 of the support tube 35. At this time, the downward movement of the cap member 37 is restricted. When the elastic ring 41 contracts in diameter, the downward movement of the cap member 37 is permitted. The elastic ring 41 of this embodiment is not limited to being made of metal, and may be made of rubber, resin, or the like, and the slit 42 may be omitted.

A ring-shaped cover 45 is attached to the top of the support cylinder 35 with a gap between it and the upper end surface of the support cylinder 35, and a ring-shaped stopper 46 is inserted into the gap so that it can move horizontally. The inner diameter of the stopper 46 is set to be the same as or smaller than the inner diameter of the hole 5 in the workpiece 4. The outer peripheral surfaces of the two engaging members 22a, 22b can abut against the inner peripheral surface of the stopper 46.

The clamp device of this embodiment is equipped with a return mechanism R that moves the clamp rod 17 so that the axis of the clamp rod 17 coincides with the axis of the cap member 37 when the clamp device is released. The return mechanism R is provided between the outer peripheral wall of the clamp rod 17 and the inner peripheral wall of the cap member 37, and is configured as follows.

The positioning portion 47 is formed in the circumferential direction so as to protrude radially outward from the outer peripheral wall of the clamp rod 17. A tapered portion 48 is formed on the upper side of the positioning portion 47 so as to taper upward. An escape portion 49 is formed on the upper side of the tapered portion 48. A reference portion 50 is formed on the inner peripheral wall of the cylindrical hole of the cap member 37. When the positioning portion 47 faces the reference portion 50, the horizontal movement of the clamp rod 17 is restricted. When the clamp rod 17 is moved downward relative to the cap member 37, the positioning portion 47 is extracted from the reference portion 50 of the cap member 37, and when the escape portion 49 faces the reference portion 50, the horizontal movement of the clamp rod 17 is permitted. The return mechanism R of this embodiment is composed of the positioning portion 47, the tapered portion 48, the escape portion 49, and the reference portion 50.

A protrusion 53 protrudes outward from the outer wall of the engagement member 22, and the lower surface of the protrusion 53 forms the pressing portion 25. The pressing portion 25 can abut against the peripheral wall of the hole 5 in the workpiece 4 from above.

The pin clamp operates as follows, as shown in Figures 6 to 10.
6, the piston 9a moves the clamp rod 17 to the upper limit position via the piston rod 9b. At this time, the positioning portion 47 of the clamp rod 17 faces the reference portion 50 of the cap member 37, so that the horizontal movement of the clamp rod 17 relative to the cap member 37 is restricted. In addition, the axis of the clamp rod 17 is substantially aligned with the axis of the cap member 37.

The workpiece 4 is moved above the pin clamp in the initial state. At this time, the axis of the hole 5 of the workpiece 4 is horizontally displaced by a distance A from the axis of the cap member 37. When the workpiece 4 is lowered, the peripheral wall of the hole 5 of the workpiece 4 abuts against the tapered portion 37a of the cap member 37. After that, the workpiece 4 is lowered while moving rightward along the tapered portion 37a of the cap member 37. At this time, the outer peripheral surface of the large diameter portion 38 of the cap member 37 is supported by a wide area on the inner peripheral surface of the tube hole 36 of the support tube 35, so that even if the workpiece 4 pushes the cap member 37 horizontally, the cap member 37 is hardly tilted relative to the housing 1. Next, the hole 5 of the workpiece 4 fits the cap member 37 from the outside. At this time, the axis of the hole 5 of the workpiece 4 is horizontally displaced by a distance B from the axis of the cap member 37.

When the pin clamp is driven to lock from the release state of Fig. 7A and Fig. 7B to the lock state of Fig. 10, pressure oil is discharged from the release chamber 12 and pressure oil is supplied to the lock chamber 11. Then, the pressing force of the pressure oil in the lock chamber 11 and the urging force of the holding spring 13 move the clamp rod 17 downward via the piston 9a and the piston rod 9b, and the clamp rod 17 moves the engaging member 22 radially outward of the clamp rod 17. The clamp rod 17 is lowered to a predetermined height position, the positioning portion 47 is extracted from the reference portion 50 of the cap member 37, and the relief portion 49 faces the reference portion 50. Therefore, the clamp rod 17 can move horizontally relative to the cap member 37. Next, as shown in Fig. 8, the outer surface of the right engaging member 22b abuts on the inner wall of the hole 5 of the workpiece 4. After that, the clamp rod 17 is lowered and moved leftward. 9, the outer surface of the left engaging member 22a engages with the inner peripheral surface of the stopper 46, and the outer surface of the right engaging member 22b also engages with the inner peripheral surface of the stopper 46. Therefore, the relative movement between the left and right engaging members 22a, 22b and the clamp rod 17 is restricted. After this, the clamp rod 17 and the engaging member 22 are lowered together, and the engaging member 22 presses the cap member 37 downward. Therefore, the elastic ring 41 attached to the cap member 37 is reduced in diameter by the step portion 44 in the cylindrical hole 36 of the support cylinder 35, and the clamp rod 17, the engaging member 22 and the cap member 37 are lowered together. As a result, the pressing portion 25 of the engaging member 22 presses the inner peripheral wall of the hole 5 of the workpiece 4 from above, as shown in FIG. As a result, the axis of the workpiece 4 is horizontally displaced by a distance B from the axis of the cap member 37, and the axis of the clamp rod 17 is approximately aligned with the axis of the hole 5 in the workpiece 4, and the pin clamp is switched from the released state shown in FIG. 7 to the locked state shown in FIG. 10.

When the pin clamp is released from the locked state of FIG. 10 to the released state of FIG. 7A, pressure oil is discharged from the lock chamber 11 and supplied to the release chamber 12. Then, the pressing force of the pressure oil in the release chamber 12 moves the piston 9a upward against the biasing force of the retaining spring 13. The piston 9a moves the clamp rod 17 upward via the piston rod 9b. At this time, the elastic restoring force of the elastic ring 41 acts on the inner circumferential surface of the cylindrical hole 36 of the support cylinder 35, generating a frictional force between the inner circumferential surface of the cylindrical hole 36 and the elastic ring 41. This frictional force leaves the cap member 37 in the lowered position. As a result, the clamp rod 17 moves the engagement members 22a, 22b on both the left and right sides radially inward of the clamp rod 17. Next, when the tapered portion 48 of the clamp rod 17 abuts against the reference portion 50 of the cap member 37, the clamp rod 17 and the left and right engaging members 22a, 22b are moved to the right while being raised. As a result, the axis of the clamp rod 17 approaches the axis of the cap member 37. Then, when the positioning portion 47 of the clamp rod 17 faces the reference portion 50 of the cap member 37, the axis of the clamp rod 17 almost coincides with the axis of the housing 1. At this time, the left and right engaging members 22a, 22b are stored inside the cap member 37. After that, the upper surface of the piston rod 9b pushes the cap member 37 upward, and the cap member 37 pushes the engaging member 22 upward. The upper surface of the large diameter portion 38 of the cap member 37 is received by the upper wall 35a of the support tube 35, and the rise of the piston 9a is stopped. As a result, the pin clamp is switched from the locked state of FIG. 10 to the released state of FIG. 7A.

The above embodiment has the following advantages.
When the hole 5 of the workpiece 4 is fitted onto the cap member 3, the cap member 3 moves the workpiece 4 from a position outside the allowable range to a position within the allowable range (desired position). At this time, the workpiece 4 exerts a force pressing the cap member 3 horizontally (to the left in the drawing), but since the outer peripheral surface of the large diameter portion 38 of the cap member 37 is supported by a wide surface on the inner peripheral surface of the cylindrical hole 36 of the support cylinder 35, the support cylinder 35 hardly tilts relative to the housing 1. In addition, since the clamp rod 17 is horizontally movable relative to the output member 9, the axis of the clamp rod 17 is moved to approach the axis of the hole 5 of the workpiece 4 during the lock drive. As a result, the engaging member 22 presses the peripheral wall of the hole 5 of the workpiece 4 evenly, so that the clamp device can clamp the workpiece 4 reliably.

When switching from the locked state to the released state, the tapered surface 48 abuts against the reference portion 50, moving the axis of the clamp rod 17 closer to the axis of the cap member 37, and the positioning portion 47 faces the reference portion 50, so that the axis of the clamp rod 17 and the axis of the cap member 37 are approximately aligned. This allows the engaging member 22 to be stored within the cap member 37 in the released state. As a result, the engaging member 22 can be prevented from being worn or damaged by the peripheral wall of the hole 5 of the workpiece 4 when attaching or removing a workpiece from the cap member 3.

11 and 12 show a first modified example of the second embodiment described above, and the second modified example differs from the first and second embodiments described above in the following respects.
Instead of the pin clamp of the second embodiment being provided with the stopper 46, the pin clamp of the first modified example has a stopper pin 56 protruding radially outward from the outer circumferential surface of the clamp rod 17. The stopper pin 56 is configured to be able to receive the engaging member 22. As a result, when the clamp rod 17 is lowered and the stopper pin 56 comes into contact with the engaging member 22 as shown in Fig. 12, the clamp rod 17 and the engaging member 22 are then lowered together. As a result, the radially outward movement of the engaging member 22 is restricted.

13 and 14 show a second modified example of the second embodiment, which differs from the first and second embodiments in the following respects.
Instead of the pin clamp of the second embodiment being provided with the stopper 46, a long hole 57 is formed in the peripheral wall of the large diameter portion 38 of the cap member 37 so as to be vertically long, and the end of the connecting pin 20C is inserted into the long hole 57. As a result, when the clamp device is driven to be locked, if the piston rod 9b is lowered to a predetermined position, the connecting pin 20C abuts against the lower end surface of the long hole 57 of the cap member 37. Thereafter, the piston rod 9b pushes down the cap member 37 via the connecting pin 20C, and the cap member 37 pushes down the engaging member 22. Also, when the clamp device is driven to be released, if the piston rod 9b is raised, the connecting pin 20C abuts against the upper end surface of the long hole 57 of the cap member 37. Thereafter, the piston rod 9b pushes up the cap member 37 via the connecting pin 20C, and the cap member 37 pushes up the engaging member 22.

15 and 16 show a third modified example of the second embodiment, which differs from the first and second embodiments in the following respects.
In the clamp device of the second embodiment described above, the positioning portion 47 is formed straight on the outer circumferential surface of the clamp rod 17 so as to be parallel to the axial direction of the clamp rod 17. In contrast, the positioning portion 47A of the third modified example is configured by a tapered outer circumferential surface that tapers upward (toward the tip) on the outer circumferential wall of the clamp rod 17. In this modified example, a reference portion 50A is formed in a tapered shape on the inner circumferential wall of the cap member 37. This allows the axis of the piston rod 9b and the axis of the clamp rod 17 to approximately coincide when the positioning portion 47A and the reference portion 50A engage over the entire circumference.

17 and 18 show a fourth modified example of the second embodiment, which differs from the first and second embodiments in the following respects.
In the clamp device of the second embodiment described above, an elastic ring 41 is attached to the cap member 37. In contrast, in the clamp device of the second modified example, a spring 64 is attached inside the cylindrical hole 36 of the support cylinder 35, between the lower end surface of the cap member 37 and the upper end surface of the housing main body 2. Therefore, the spring 64 urges the cap member 37 upward relative to the housing 1.

The pin clamp described above, as shown in Figures 17 and 18, operates as follows.
The workpiece 4 is moved above the pin clamp in the initial state shown in Fig. 17. At this time, the axis of the hole 5 in the workpiece 4 is horizontally displaced from the axis of the cap member 37 of the pin clamp by a distance A. When the workpiece 4 is lowered, the peripheral wall of the hole 5 in the workpiece 4 comes into contact with the tapered portion 37a of the cap member 37 of the pin clamp. Thereafter, the workpiece 4 is lowered while moving rightward along the tapered portion 37a of the cap member 37. Subsequently, the hole 5 in the workpiece 4 fits the cap member 37 from the outside. At this time, the axis of the hole 5 in the workpiece 4 is horizontally displaced from the axis of the cap member 37 by a distance B.

When the pin clamp is locked from the release state of FIG. 17 to the lock state of FIG. 18, pressure oil is discharged from the release chamber 12 and supplied to the lock chamber 11. Then, the pressing force of the pressure oil in the lock chamber 11 and the urging force of the holding spring 13 move the clamp rod 17 down through the piston 9a and the piston rod 9b. At this time, when the clamp rod 17 is lowered to a predetermined height position, the positioning portion 47 of the clamp rod 17 is separated from the reference portion 50 of the cap member 37 (the facing state is released), and the relief portion 49 faces the reference portion 50, so that the clamp rod 17 is allowed to move in the horizontal direction. The clamp rod 17 moves the engagement member 22 outward in the radial direction of the clamp rod 17. Next, the outer surface of the right engagement member 22 abuts against the inner wall of the hole 5 of the workpiece 4. After that, the clamp rod 17 is lowered and moved to the left. The outer surface of the left engagement member 22 a abuts against the inner wall of the hole 5 of the workpiece 4. This limits the relative movement between the clamp rod 17 and the engaging member 22. After that, the clamp rod 17 and the engaging member 22 are lowered together, and the engaging member 22 pushes the cap member 37 downward against the biasing force of the spring 64. As a result, the axis of the cap member 37 is horizontally displaced by a distance B from the axis of the hole 5 in the workpiece 4, and the pressing portion 25 of the engaging member 22 reliably presses the periphery of the hole 5 in the workpiece 4 from above, with the axis of the clamp rod 17 approximately coinciding with the axis of the cap member 37. As a result, the pin clamp is switched from the release state of FIG. 17 to the lock state of FIG. 18.

When the pin clamp is released from the locked state shown in FIG. 18 to the released state shown in FIG. 17, pressure oil is discharged from the lock chamber 11 and supplied to the release chamber 12. Then, the pressing force of the pressure oil in the release chamber 12 moves the piston 9a upward against the biasing force of the retaining spring 13. When the piston 9a moves the clamp rod 17 upward via the piston rod 9b, the clamp rod 17 moves the left and right engaging members 22a, 22b radially inward of the clamp rod 17. At this time, the biasing force of the spring 64 pushes the cap member 37 upward. Next, when the tapered portion 48 of the clamp rod 17 abuts against the reference portion 50 of the cap member 37, the clamp rod 17 and the left and right engaging members 22 are moved to the right so that the axis of the clamp rod 17 approaches the axis of the cap member 37. When the positioning portion 47 of the clamp rod 17 faces the reference portion 50 of the cap member 37, the axis of the clamp rod 17 approximately coincides with the axis of the housing 1. As a result, the engaging member 22 is stored inside the cap member 37. The spring 64 pushes the cap member 37 upward, and the cap member 37 pushes the engaging member 22 upward. The upper surface of the large diameter portion of the cap member 37 is received by the upper wall of the support tube 35, and the piston rod 9b is received by the cap member 37, stopping the rise of the piston 9a. As a result, the pin clamp is switched from the locked state to the released state.

The above embodiments can be modified as follows.
The present invention is not limited to application to a clamping device (hole clamp) that presses the inner surface of a hole in a workpiece, pallet, tool, etc., and a clamping device (pin clamp) that presses the peripheral wall of a hole in the workpiece, etc. from above, but may also be applied to other clamping devices, robot tool changers, etc.
The pressure fluid supplied to drive the clamp device may be other liquids or gases such as compressed air instead of the pressure oil exemplified above.
Instead of mounting the holding spring 13 in the lock chamber 11, a release spring may be mounted in the release chamber 12.
Moreover, a single-acting cylinder may be used in place of the double-acting cylinder exemplified in the above embodiment.
Furthermore, instead of the hydraulic cylinder shown as an example, a pneumatic cylinder or an electric actuator may be used.
The cap members 3, 37 may be provided so as to protrude from the housing 1 so as to be integral with the housing 1, or may be inserted into the housing 1 so as to be movable in the vertical direction.
The output member 9 may be constituted by only a piston, instead of having the piston 9a and the piston rod 9b. In this case, the clamp rod 17 is connected by a pin to an insertion hole formed in the upper part of the piston so as to be movable in the horizontal direction and the up-down direction, or only in the horizontal direction.
The number of the engaging members 22 provided on the outer peripheral wall of the clamp rod 17 is not limited to two or three, and four or more engaging members may be provided.
The reference portion 31, 50, 50A may be provided on the inner peripheral wall of the cylindrical hole of the cap member 3, 37, or may be formed on another wall such as the inner peripheral wall of the insertion hole 16 of the piston rod 9b. The reference portion 31, 50, 50A may be formed on the inner peripheral wall of the cylindrical hole of the cap member 3, 37 or the inner peripheral wall of the insertion hole 16 of the piston rod 9b straight so as to be parallel to the axis of the cylindrical hole or the insertion hole, or may be formed tapered so as to be inclined with respect to the axis of the cylindrical hole or the insertion hole.
In order to hold the cap members 3, 37 at their upper limit positions, instead of providing an elastic ring and a step portion as in the second embodiment, a spring 64 may be provided as in the second variant of the second embodiment, or vice versa.
Of course, various other modifications can be made within the scope of what a person skilled in the art can imagine.

1: Housing, 3: Cap member, 4: Clamp object (workpiece), 5: Hole, 8: Cylindrical hole, 9: Output member, 16: Insertion hole, 17: Clamp rod, 19, 19A, 19B: Long hole, 20, 20A, 20B, 20C: Connecting pin, 22: Engagement member, 24: Guide hole, 28: Positioning portion, 30: Relief portion, 31: Reference portion, 36: Cylindrical hole, 37: Cap member, 46: Stopper, 47: Positioning portion, 49: Relief portion, 50: Reference portion, 56: Stopper, 57: Long hole.

Claims (8)

a cylindrical cap member (3, 37) that protrudes from the tip wall of the housing (1) toward the tip side and is insertable into a hole (5) of an object to be clamped (4);
an output member (9) movably inserted within the housing (1);
a clamp rod (17) that is inserted into the cylindrical hole (8, 36) of the cap member (3, 37) so as to be movable in an axial direction and a radial direction, and that is connected to the output member (9) so as to be movable in the radial direction of the output member (9);
an engaging member (22) that is inserted into a guide hole (24) that penetrates a cylindrical wall of the cap member (3, 37) and is moved along the guide hole (24) by the clamp rod (17) ;
an insertion hole (16) formed at a tip end of the output member (9), into which the clamp rod (17) is inserted;
a positioning portion (28) protruding radially outward from an outer peripheral wall of the clamp rod (17);
a relief portion (30) formed on an outer peripheral wall of the clamp rod (17) at a location separate from the positioning portion (28);
A reference portion (31) formed on an inner peripheral wall of the insertion hole (16),
the clamp rod (17) is connected to the output member (9) so as to be movable in a horizontal and axial direction, and when the clamp rod (17) is moved in the axial direction relative to the output member (9) and the positioning portion (28) faces or abuts against the reference portion (31), radial movement of the clamp rod (17) is restricted;
When the clamp rod (17) is moved in the axial direction relative to the output member (9) and the relief portion (30) faces or abuts against the reference portion (31), the clamp rod (17) becomes movable in the radial direction.
A clamping device characterized by:
2. The clamping device of claim 1,
A long hole (19) that penetrates the clamp rod (17) in a radial direction so as to be elongated in the axial direction;
a connecting pin (20) that protrudes from a peripheral wall of the insertion hole (16) toward inside the insertion hole (16) and is inserted into the long hole (19). 2. The clamping device of claim 1,
A hole (19A) that penetrates radially through a peripheral wall of the insertion hole (16);
a connecting pin (20A) that protrudes radially outward from the clamp rod (17) and is inserted into the hole (19A). 2. The clamping device of claim 1,
A long hole (19B) that penetrates the peripheral wall of the insertion hole (16) in the radial direction so as to be elongated in the axial direction;
a connecting pin (20B) that protrudes radially outward from the clamp rod (17) and is inserted into the long hole (19B). a cylindrical cap member (37) that protrudes from the tip wall of the housing (1) toward the tip side and can be inserted into a hole (5) of an object to be clamped (4);
an output member (9) movably inserted within the housing (1);
a clamp rod (17) that is inserted into the cylindrical hole (8, 36) of the cap member (37) so as to be movable in an axial direction and a radial direction, and that is connected to the output member (9) so as to be movable in the radial direction of the output member (9);
an engaging member (22) that is inserted into a guide hole (24) that penetrates a cylindrical wall of the cap member (37) and is moved along the guide hole (24) by the clamp rod (17);
a positioning portion (47) protruding radially outward from an outer peripheral wall of the clamp rod (17);
a relief portion (49) formed on an outer peripheral wall of the clamp rod (17) at a location separate from the positioning portion (47);
a reference portion (50) formed on an inner peripheral wall of the cylindrical hole (36) of the cap member (37),
When the clamp rod (17) is moved in the axial direction and the positioning portion (47) faces the reference portion (50), the radial movement of the clamp rod (17) is restricted,
A clamp device characterized in that, when the clamp rod (17) is moved axially and the relief portion (49) faces the reference portion (50), the clamp rod (17) is capable of moving radially. In the clamping device according to claim 1 or 5,
A clamping device characterized in that an annular stopper (46) is attached to the tip wall of the housing (1) so as to be movable in the radial direction, and the outer surface of the engaging member (22) can abut against the inner peripheral wall of the stopper (46). In the clamping device according to claim 1 or 5,
A clamp device characterized in that a stopper (56) protrudes outward from the clamp rod (17), and the stopper (56) is capable of abutting the tip of the engaging member (22) with a predetermined gap therebetween. a cylindrical cap member (37) that protrudes from the tip wall of the housing (1) toward the tip side and can be inserted into a hole (5) of an object to be clamped (4);
an output member (9) movably inserted within the housing (1);
a clamp rod (17) that is inserted into the cylindrical hole (8, 36) of the cap member (37) so as to be movable in an axial direction and a radial direction, and that is connected to the output member (9) so as to be movable in the radial direction of the output member (9);
an engaging member (22) that is inserted into a guide hole (24) that penetrates a cylindrical wall of the cap member (37) and is moved along the guide hole (24) by the clamp rod (17);
a long hole (57) is radially penetrated in the cylindrical wall of the cap member (37) so as to be elongated in the axial direction, and an end of a connecting pin (20C) connecting the output member (9) and the clamp rod (17) is inserted into the long hole (57) so as to be movable along the long hole (57).