Swing clamp device

Abstract

Provided is a highly durable, compact rotary clamp device.　In a housing body 2, a large-diameter hole 6 and a medium-diameter hole 7 are continuously formed in this order from a lower side in an axial direction. A cylindrical protruding member 3 which is hermetically inserted in the large-diameter hole 6 is screwed into the housing body 2. A key member 22 is inserted between the medium-diameter hole 7 and a cylindrical retainer 15 inserted in the medium-diameter hole 7. The retainer 15 is positioned relative to the housing body 2 in a circumferential direction by the key member 22.

Description

Technical Field

[0001] The present invention relates to a swivel clamp device that fixes an object to be fixed, such as a workpiece, a mold, or a tool, to a table or a robot arm by rotating and lowering a clamp arm.

Background Art

[0002] Conventionally, there is a swivel clamp device described in Patent Document 1 (Japanese Utility Model Laid-Open No. 5-52304). The prior art is configured as follows. In the swivel clamp device shown in FIG. 5 of Patent Document 1, a piston is inserted into a cylinder hole of a cylinder tube. A cylindrical rod cover is inserted into the tip of the cylinder hole of the cylinder tube and protrudes upward from the cylinder tube. A piston rod protruding from the piston toward the tip side is inserted into the cylinder hole of the rod cover, and the piston rod protrudes outside the cylinder cover. The rod cover is received from below by a stepped portion formed on the inner peripheral wall of the cylinder hole of the cylinder tube and is prevented from coming out of the cylinder hole of the cylinder tube by a retaining ring. Further, a screw hole is penetrated in the radial direction through the cylinder wall of the cylinder tube, and a screw is screwed into the screw hole. The tip of the screw is inserted into a recess formed on the outer peripheral wall of the rod cover. Thereby, the rod cover is prevented from rotating with respect to the cylinder tube. In addition, in the swivel clamp device shown in FIG. 1 of Patent Document 1, instead of the above-described retaining ring, the rod cover is fixed to the cylinder tube by a ring nut.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above prior art has the following problems. A retaining ring is mounted on the inner peripheral wall of the cylinder tube between the cylinder tube and the rod cover to prevent the rod cover from coming off the cylinder tube. To mount the retaining ring between the cylinder tube and the rod cover, it is necessary to provide a space for inserting the retaining ring between the cylinder tube and the rod cover, a space for the insertion operation, a space for inserting the mounting tool, and the like. For this reason, the radial dimension of the cylinder tube becomes large. Further, when the piston moves to the tip limit position, the screw and the retaining ring receive the impact caused by the piston colliding with the rod cover. In order to have a structure that can withstand the impact, for example, a structure for preventing loosening such as making the diameter dimension of the screw as large as possible or increasing the number of turns of the screw groove is required, and it is necessary to increase the thickness and width dimension of the retaining ring to improve durability. For this reason, it is necessary to set the wall thickness of the cylinder tube wall to be sufficient. Therefore, the radial dimension of the rotary clamp device becomes large. Also, in the rotary clamp device shown in FIG. 1 of Patent Document 1, a ring nut is mounted from above between the outer peripheral surface of the rod cover and the inner peripheral surface of the cylinder tube. For this reason, it is necessary to provide a space for inserting the ring nut between the cylinder tube and the rod cover and a space for inserting the tool. Therefore, the radial dimension of the rotary clamp device becomes large. An object of the present invention is to provide a rotary clamp device having high durability and being compact.

Means for Solving the Problems

[0005] To achieve the above object, the present invention configures a rotary clamp device as follows, for example, as shown in FIGS. 1 and 2. A large-diameter hole 6, a medium-diameter hole 7, and a small-diameter hole 8 are formed in the housing body 2 in this order from the tip side in the axial direction to the base end side. A cylindrical protruding member 3 is inserted into the large-diameter hole 6 in a sealed manner. A male screw portion 11 formed on the outer peripheral wall of the protruding member 3 is screwed into a female screw portion 10 formed on the inner peripheral wall of the medium-diameter hole 7. A cylindrical retainer 15 is inserted into the medium-diameter hole 7. A first key groove 20 is formed in the inner peripheral wall of the medium-diameter hole 7 in the axial direction. A second key groove 21 facing the first key groove 20 is formed in the outer peripheral wall of the retainer 15 in the axial direction. A key member 22 is mounted between the first key groove 20 and the second key groove 21. A piston 25 is inserted into the small-diameter hole 8 in a sealed manner so as to be axially movable. A piston rod 30 protruding from the piston 25 toward the tip side in the axial direction passes through the cylindrical hole 31 of the retainer 15 and the cylindrical hole 19 of the protruding member 3 and protrudes outward from the protruding member 3. An engaging member 38 protrudes radially inward from the inner peripheral surface of the retainer 15. The engaging member 38 is inserted into a spiral groove 39 and a straight groove 40 formed continuously in this order from the base end side in the axial direction on the outer peripheral wall of the piston rod 30. A part of the peripheral wall of the first key groove 20 is formed to be radially outward of the inner peripheral surface of the large-diameter hole 6.

[0006] The present invention has the following operational effects. Since the above-mentioned protruding member is directly and firmly screwed to the housing body by the male screw portion and the female screw portion, the durability of the engaging portion between the protruding member and the housing body can be enhanced. Also, since there is no need to provide a separate member for connecting between the protruding member and the housing body, the swivel clamp device can be made smaller.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Best Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2, and 3. The housing 1 of the above-described rotary clamp device has a housing body 2, a protruding member 3, and a lid member 4, and the housing body 2 is formed of an aluminum drawn material. A cylinder hole 5 is formed in the housing body 2. The cylinder hole 5 has a large-diameter hole 6, a medium-diameter hole 7, and a small-diameter hole 8 formed in order from the upper side (the tip side in the axial direction).

[0009] The lower part of the protruding member 3 is inserted into the large-diameter hole 6. A female screw portion 10 is formed in the upper half of the medium-diameter hole 7, and a male screw portion 11 formed on the protruding member 3 is screwed into the female screw portion 10. For this reason, the protruding member 3 is fixed to the housing body 2 in a state of protruding upward from the housing body 2. A housing groove 12 is formed in the circumferential direction above the male screw portion 11 of the protruding member 3, and a sealing member 13 such as an O-ring is attached to the housing groove 12. In a state where the protruding member 3 is screwed into the housing body 2, the sealing member 13 is brought into close contact with the sealed surface formed by the inner peripheral surface of the large-diameter hole 6, so that the space between the inner peripheral surface of the large-diameter hole 6 and the outer peripheral surface of the protruding member 3 is sealed.

[0010] A cylindrical retainer 15 is inserted into the lower half of the above-mentioned medium-diameter hole 7 (see FIGS. 3A and 3B), and the retainer 15 is received from below by a stepped portion 16 formed between the small-diameter hole 8 and the medium-diameter hole 7. The retainer 15 has a large-diameter portion 17 and a small-diameter portion 18 formed in order from the lower side. The small-diameter portion 18 is inserted into a cylindrical hole 19 of the protruding member 3. Further, a first key groove 20 is formed in the vertical direction on the inner peripheral wall of the medium-diameter hole 7, and a second key groove 21 is formed at a position on the outer peripheral wall of the large-diameter portion 17 of the retainer 15 facing the first key groove 20. The bottom surface of the first key groove 20, which is the deepest part, is set to be radially outward of the inner peripheral surface of the large-diameter hole 6. Further, a parallel pin as a key member 22 is mounted with a sliding gap between the first key groove 20 and the second key groove 21 (see FIG. 3B). The retainer 15 is provided with a through groove 23 continuous with the second key groove 21 on the small-diameter portion 18 side, facilitating the entry of the key member 22. Thereby, the retainer 15 is positioned in the circumferential direction and prevented from rotating with respect to the housing body 2.

[0011] A piston 25 is inserted into the above-mentioned small-diameter hole 8 so as to be movable in the vertical direction (axial direction of the cylinder hole 5) in a sealed state. A clamp chamber 26 is formed above the piston 25, and an unclamp chamber 27 is formed below the piston 25. Further, a clamp supply / discharge port 28 for supplying and discharging compressed air from a compressed air source is formed in the body portion of the housing body 2, and the clamp supply / discharge port 28 communicates with the clamp chamber 26. An unclamp supply / discharge port 29 is formed in the body portion of the housing body 2 below the clamp supply / discharge port 28, and the unclamp supply / discharge port 29 communicates with the unclamp chamber 27.

[0012] The piston rod 30 projects upward from the piston 25 described above. The piston rod 30 is inserted into the cylindrical hole 31 of the retainer 15 and is inserted into the cylindrical hole 19 of the protruding member 3 so as to be vertically movable in a sealed manner. The piston rod 30 projects outward from the protruding member 3. One end 33a of the clamp arm 33 is screwed to the tip of the piston rod 30. A pressing portion 34 is formed on the back surface of the other end 33b of the clamp arm 33, and the pressing portion 34 can abut against the workpiece (object to be fixed) 35.

[0013] A spherical engaging ball (engaging member) 38 is mounted in a recess 37 formed on the inner peripheral wall of the retainer 15. The engaging ball 38 projects radially inward from the inner peripheral surface of the retainer 15. The engaging ball 38 is inserted into a spiral groove 39 and a straight groove 40 that are successively formed on the outer peripheral wall of the piston rod 30 from the lower side.

[0014] A step portion 41 is formed in the circumferential direction on the outer peripheral wall of the piston rod 30 above the spiral groove 39. Further, a protruding portion 42 projects radially inward from the inner peripheral surface of the cylindrical hole 19 of the protruding member 3. A receiving groove 43 is formed in the circumferential direction on the inner peripheral wall of the cylindrical hole 19 below the protruding portion 42. An impact absorbing member 44 such as a rubber, resin, or metal spring material is mounted in the receiving groove 43. When the piston rod 30 is moved to the upper limit position, the step portion 41 of the piston rod 30 is received by the protruding portion 42 of the protruding member 3 via the impact absorbing member 44.

[0015] As shown in FIGS. 1 and 2, the above-described rotary clamping device operates as follows. In the initial state (unclamped state) of FIG. 1, compressed air (pressure fluid) is discharged from the clamp chamber 26, and compressed air (pressure fluid) is supplied to the unclamp chamber 27. By the compressed air in the unclamp chamber 27, the piston 25 and the piston rod 30 are moved to the upper limit position, and the engaging portion formed on the step portion 41 of the piston rod 30 is received from above by the impact absorbing member 44.

[0016] When switching from the unclamped state in Fig. 1 to the clamped state in Fig. 2, first, the compressed air in the unclamp chamber 27 is discharged to the outside through the unclamp supply / discharge port 29, and the compressed air from the compressed air source is supplied to the clamp chamber 26 through the clamp supply / discharge port 28. The piston 25 is moved downward by the compressed air in the clamp chamber 26, and the piston 25 is moved downward while being rotated in the clockwise direction in plan view by the spiral groove 39 and the engagement ball 38. Next, the piston 25 is moved straight downward by the straight groove 40 and the engagement ball 38. The clamp arm 33 presses the workpiece 35 placed on the table T from above to stop the downward movement of the piston 25. Thereby, the rotary clamping device is switched from the unclamped state in Fig. 1 to the clamped state in Fig. 2.

[0017] When switching from the clamped state in Fig. 2 to the unclamped state in Fig. 1, the compressed air in the clamp chamber 26 is discharged, and compressed air is supplied to the unclamp chamber 27. Then, the compressed air in the unclamp chamber 27 moves the piston 25 and the piston rod 30 straight upward. Next, the clamp arm 33 is moved upward while being rotated in the counterclockwise direction in plan view. The engaging portion of the piston rod 30 is received from above by the shock absorbing member 44 of the protruding member 3 to stop the upward movement of the piston rod 30. Thereby, the rotary clamping device is switched from the clamped state in Fig. 2 to the unclamped state in Fig. 1.

[0018] The above embodiment has the following advantages. Since the above-mentioned protruding member 3 is directly and firmly screwed into the housing body 2 by its female screw portion 10 and the male screw portion 11 of the housing body 2, there is no need to separately provide a member for connecting between the protruding member 3 and the housing body 2. As a result, the radial dimensions of the housing body 2 and the protruding member 3 can be reduced. Consequently, the rotary clamping device can be made smaller.

[0019] As shown in FIGS. 1 and 2, when the rotary clamping device is viewed in cross section, the bottom surface of the first key groove 20 is formed to be radially outward of the inner peripheral surface of the large-diameter hole 6 of the housing body 2. Therefore, the key member 22 is balancedly arranged at a position straddling the outer and inner sides in the radial direction with the inner peripheral surface of the large-diameter hole 6 where the housing body 2 and the protruding member 3 are in contact therebetween. As a result, the thickness of the cylindrical wall of the housing body 2 and the thickness of the cylindrical wall of the retainer 15 can be made small, so that the radial dimensions of the housing body 2 and the retainer 15 can be made small. As a result, the overall dimensions of the rotary clamping device can be made small.

[0020] When the piston 25 and the piston rod 30 move in the vertical direction, the peripheral wall of the spiral groove 39 of the piston rod 30 presses the retainer 15 in the circumferential direction via the engagement ball 38. The retainer 15 is reliably received by the housing body 2 via the key member 22 and is prevented from rotating. Therefore, it is difficult for the pressing force in the circumferential direction to be transmitted to the protruding member 3 which is a member different from the retainer 15. Accordingly, loosening of the screwed portion between the housing body 2 and the protruding member 3 due to the pressing force in the circumferential direction acting thereon is prevented. Thus, wear and breakage of the screwed portion and its peripheral members caused by loosening can be prevented, and the durability of the rotary clamping device can be improved.

[0021] The thread groove of the female thread portion 10 is formed by winding a plurality of turns in the middle-diameter hole 7 of the housing body 2. Compared with the thread groove of the screw hole formed in the cylinder tube wall in the conventional rotary clamping device described above, the thread groove of the female thread portion 10 of the present invention is formed longer. Therefore, when the female thread portion 10 is screwed with the male thread portion 11 of the protruding member 3 at an engagement portion with a large area, a large frictional force can act on the engagement portion. Thus, even if an impact when the piston rod 30 collides with the protruding member 3 acts on the engagement portion, loosening of the engagement portion can be prevented. Accordingly, wear and breakage of the engagement portion and its peripheral members due to loosening can be prevented, and the durability of the rotary clamping device can be improved.

[0022] Each of the above embodiments can be modified as follows. Instead of the exemplified compressed air, the pressure fluid may be another gas or a liquid such as hydraulic oil or water. Instead of aluminum, the housing body 2 may be formed of another metal, such as iron, or another material. The housing body 2 is not limited to a drawn material and may be a member formed by machining. Instead of the protruding member 3 being received by the stepped portion 16 of the housing body 2 via the retainer 15 by screwing the protruding member 3 into the housing body 2, the protruding member 3 may be received by the housing body 2 (the lower end wall of the first key groove 20) via the key member 22 or directly by the housing body 2. In this case, a gap will be formed between the protruding member 3 and the retainer 15. As a result, due to the vertical movement of the piston 25 or the like, the pressing force that the peripheral wall of the spiral groove 39 acts on the retainer 15 in the direction around the axis via the engaging ball 38 is difficult to be transmitted to the protruding member 3. As a result, loosening of the screwed portion due to the circumferential pressing force acting on the screwed portion between the housing body 2 and the protruding member 3 is prevented. Therefore, wear and damage caused by loosening can be prevented, and the durability of the rotary clamp device can be increased. Instead of the spherical engaging ball 38, the engaging member may be a member having another shape, such as a substantially cylindrical shape or a rectangular shape. Instead of the engaging member being provided on the retainer 15, it may be provided so as to protrude from the outer peripheral wall of the piston rod 30. In this case, a linear groove and a spiral groove are provided continuously in order from the lower side (penetrating the peripheral wall) on the peripheral wall of the retainer 15. The key member 22 is not limited to being constituted by a cylindrical parallel pin, and may be a polygonal prism-shaped pin or a spherical member. Also, the key member 22 is not limited to being provided with only one, and a plurality of key members 22 may be provided at predetermined intervals on the peripheral wall of the retainer. Instead of being attached to the protrusion 42 of the protruding member 3, the impact absorbing member 44 may be attached to the inner peripheral wall of the large-diameter hole 6 of the housing body 2, the lower end portion of the retainer 15, the upper portion of the piston 25, and the stepped portion 41 of the piston rod 30. Of course, various other changes can be made within the scope that can be assumed by those skilled in the art.

Explanation of Reference Numerals

[0023] 2 Housing body 3 Protruding member 6 Large-diameter hole 7 Medium-diameter hole 8 Small-diameter hole 10 Female screw portion 11 Male screw portion 15 Retainer 20 First key groove 21 Second key groove 22 Key member 25 Piston 30 Piston rod 31 Cylindrical hole 19 Cylindrical hole 38 Engaging ball 39 Spiral groove 40 Straight groove

Claims

【Claim 1】 A housing body (2); A large-diameter hole (6), a medium-diameter hole (7), and a small-diameter hole (8) formed in the housing body (2) in order from the tip side to the base side in the axial direction; A cylindrical protruding member (3) that is inserted into the large-diameter hole (6) in a confidential manner and protrudes from the housing body (2) to the tip side in the axial direction; A male screw portion (11) formed on the outer peripheral wall of the protruding member (3) and screwed into a female screw portion (10) formed on the inner peripheral wall of the medium-diameter hole (7); A cylindrical retainer (15) inserted into the medium-diameter hole (7); A first key groove (20) formed in the inner peripheral wall of the medium-diameter hole (7) in the axial direction; A second key groove (21) formed in the outer peripheral wall of the retainer (15) in the axial direction so as to face the first key groove (20); A key member (22) mounted between the first key groove (20) and the second key groove (21); A piston (25) inserted into the small-diameter hole (8) in a confidential manner and movable in the axial direction; A piston rod (30) protruding from the piston (25) to the tip side in the axial direction and protruding outward from the protruding member (3) through the cylindrical hole (31) of the retainer (15) and the cylindrical hole (19) of the protruding member (3); An engaging member (38) protruding radially inward from the inner peripheral surface of the retainer (15); A spiral groove (39) and a straight groove (40) formed in the outer peripheral wall of the piston rod (30) in order from the base side in the axial direction, the spiral groove (39) and the straight groove (40) into which the engaging member (38) is inserted; and A part of the peripheral wall of the first key groove (20) is formed to be radially outward of the inner peripheral surface of the large-diameter hole (6). A swivel clamp device characterized by this.

Images