Work holding device

Abstract

To provide a workpiece holding device which can arrange a plurality of shaft members in a compact state.SOLUTION: A workpiece holding device includes a body 42, a plurality of shaft members 7 capable of being brought into contact with workpiece, and a plurality of clamp devices that are mounted on the body 42, to which the plurality of shaft members 7 are inserted, and that can be switched between a non-clamp state in which the shaft members 7 are released and a clamp state in which the shaft members 7 are clamped, wherein the plurality of shaft members 7 include a first shaft member 7-1 arranged at apexes of a first regular n-polygon h1 and a second shaft member 7-2 arranged at apexes of a second regular n-polygon h2, which has one side longer than the first regular n-polygon h1 and is substantially shifted by 180° / n with respect to the first regular n-polygon h1, in axial view of the body 42. Here, n is any one of integers of 4 or more.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a workpiece holding device for holding a workpiece, and more particularly to a workpiece holding device that uses a clamping device. [Background technology]

[0002] A clamping device that switches between an unclamped state in which a shaft member is released and a clamped state in which the shaft member is clamped is known (see Patent Document 1). This clamping device includes an outer cylinder into which the shaft member is inserted, rolling elements disposed in a wedge-shaped space between the outer cylinder and the shaft, and a retainer that holds the rolling elements. The shaft member can be clamped by moving the outer cylinder relative to the retainer in one direction so that the rolling elements roll into the smaller diameter side of the wedge-shaped space. On the other hand, the shaft member can be released by moving the outer cylinder relative to the retainer in the opposite direction so that the rolling elements move into the larger diameter side of the wedge-shaped space.

[0003] By using this clamping device, it is possible to construct a work holding device that grips, sucks, supports, etc. a workpiece. For example, by placing a pair of shaft members on the left and right of the workpiece and sandwiching the workpiece between the pair of shaft members fixed by the clamping device, the workpiece can be gripped. Also, by providing a suction pad at the tip of the shaft member fixed by the clamping device, the workpiece can be sucked. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-4508 Summary of the Invention [Problem to be solved by the invention]

[0005] If multiple shaft members can be arranged in a densely packed state, it will be possible to hold, suck, support, etc. a wide variety of workpieces.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a workpiece holding device that allows a plurality of shaft members to be arranged in a densely packed state. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, one aspect of the present invention is a clamping mechanism including a main body, a plurality of shaft members that can contact a workpiece, a clamping mechanism attached to the main body, into which the plurality of shaft members are inserted, and a clamping state in which the shaft members are released and a clamping state in which the shaft members are released. restricts axial movement of a workpiece holding device including a plurality of clamping devices switchable to a clamping state, wherein, when viewed in the axial direction of the main body, the plurality of shaft members include first shaft members arranged at vertices of a first regular n-gon, and second shaft members arranged at vertices of a second regular n-gon having one side longer than that of the first regular n-gon and shifted substantially by 180° / n with respect to the first regular n-gon; Each shaft member is inserted into each clamping device, and the shaft members grip the workpiece without contacting each other. This is a workpiece holding device. However, n is an integer greater than or equal to 4. [Effects of the Invention]

[0008] According to the present invention, a triangle can be formed by two adjacent inner first shaft members and one outer second shaft member, and multiple shaft members can be arranged in a densely packed state. [Brief explanation of the drawings]

[0009] [Figure 1] 3 is a cross-sectional view of a clamp device incorporated in the workpiece holding device of the present embodiment. FIG. [Figure 2] FIG. 10 is a diagram showing another example of a clamping device. [Figure 3] 3A and 3B are plan views of a workpiece holding device according to a first embodiment of the present invention (FIG. 3A shows a state before holding a workpiece, and FIG. 3B shows a state after holding a workpiece). [Figure 4] 4A and 4B are enlarged views of the main body of the workpiece holding device according to the first embodiment of the present invention (FIG. 4A shows the clamping device in an unclamped state, and FIG. 4B shows the clamped state). [Figure 5]FIG. 10 is a perspective view of a workpiece holding device according to a second embodiment of the present invention (in a state before holding a workpiece). [Figure 6] FIG. 10 is a perspective view of a workpiece holding device according to a second embodiment of the present invention (in a state after holding a workpiece). [Figure 7] 7A and 7B are horizontal cross-sectional views of a main body of a workpiece holding device according to a second embodiment of the present invention (FIG. 7A shows the clamping device in an unclamped state, and FIG. 7B shows the clamped state). [Figure 8] 8A and 8B are horizontal cross-sectional views of a shaft member of a workpiece holding device according to a second embodiment of the present invention (FIG. 8A shows the clamping device in an unclamped state, and FIG. 8B shows the clamped state). [Figure 9] 9A and 9B are horizontal cross-sectional views of a trigger member of a workpiece holding device according to a second embodiment of the present invention (FIG. 9A shows the initial position of the trigger member, and FIG. 9B shows the actuated position of the trigger member). [Figure 10] FIG. 6 is a view taken along the arrow X in FIG. 5. [Figure 11] 11A and 11B are horizontal cross-sectional views of a main body of a workpiece holding device according to a third embodiment of the present invention (FIG. 11A shows the clamping device in an unclamped state, and FIG. 11B shows the clamped state). [Figure 12] 12A and 12B are diagrams showing a workpiece holding device according to a fourth embodiment of the present invention (FIG. 12A is a side view (unclamped state), and FIG. 12B is a bottom view). [Figure 13] FIG. 10 is a side view (clamped state) of a workpiece holding device according to a fourth embodiment of the present invention. [Figure 14] 14A and 14B are diagrams showing a workpiece holding device according to a fifth embodiment of the present invention (FIG. 14A is a side view (unclamped state), and FIG. 14B is a bottom view). [Figure 15] FIG. 10 is a side view (clamped state) of a workpiece holding device according to a fifth embodiment of the present invention. [Figure 16] 16A and 16B are diagrams showing a workpiece holding device according to a sixth embodiment of the present invention (FIG. 16A is a side view (unclamped state), and FIG. 16B is a bottom view). [Figure 17] FIG. 10 is a side view (clamped state) of a workpiece holding device according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a workpiece holding device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention can be embodied in various forms and is not limited to the embodiments described herein. The present embodiment is provided with the intention that those skilled in the art will be able to understand the invention by fully disclosing the specification. (clamping device)

[0011] FIG. 1 is a cross-sectional view of a clamping device 1 incorporated into a workpiece holding device of this embodiment. First, the configuration of the clamping device 1 will be described. The clamping device 1 is configured to switch between an unclamped state in which the shaft member 7 is released and a clamped state in which the shaft member 7 is clamped. The clamping device 1 includes an outer cylinder 2, rolling elements 3, a retainer 4, and a spring 5. The clamping device 1 is attached to a fixed plate 12a of a main body 12 (see FIG. 3).

[0012] The outer cylinder 2 is cylindrical. A shaft member 7 is inserted into the outer cylinder 2. A tapered surface 2a is formed on the inner surface of the outer cylinder 2, with the inner diameter gradually decreasing in the direction B in FIG. 1. A wedge-shaped space S is formed between the outer surface of the shaft member 7 and the tapered surface 2a of the outer cylinder 2. The rolling elements 3 are housed in this wedge-shaped space S. The perpendicular cross section of the outer cylinder 2 may be circular or polygonal. The perpendicular cross section of the shaft member 7 may also be circular or polygonal.

[0013] The rolling elements 3 are rollers or balls. The rollers may be barrel-shaped or drum-shaped. A plurality of the rolling elements 3 are arranged in the circumferential direction of the wedge-shaped space S.

[0014] The retainer 4 holds the rolling elements 3. The retainer 4 is cylindrical. An opening 4a is formed in the retainer 4 to accommodate the rolling elements 3. The rolling elements 3 are accommodated in the opening 4a so that they can roll. One end of the retainer 4 protrudes in the axial direction from the outer cylinder 2. One end of the retainer 4 is fixed to a fixing plate 12a.

[0015] The spring 5 is housed in the outer cylinder 2. The spring 5 is disposed between a retainer 4 and a snap ring 2b attached to the outer cylinder 2. The spring 5 biases the rolling elements 3 held by the retainer 4 toward the smaller diameter side of the wedge-shaped space S.

[0016] As shown in FIG. 1, when the outer cylinder is moved relative to the retainer 4 in direction A (one direction), the rolling elements 3 roll into the smaller diameter side of the wedge-shaped space S. The shaft member 7 is fastened by the rolling elements 3 and clamped by the rolling elements 3 (the clamping device 1 is in a clamped state). At this time, the load P acting on the shaft member 7 is transmitted to the fixed plate 12a via the rolling elements 3 and the retainer 4. On the other hand, when the outer cylinder is moved relative to the retainer 4 in direction B (the opposite direction), the rolling elements 3 move to the larger diameter side of the wedge-shaped space S. The shaft member 7 is released from the rolling elements 3 and becomes movable in the axial direction (the clamping device 1 is in an unclamped state).

[0017] As shown in Figure 2, the outer cylinder 2 of the clamping device 1 may be fixed to the fixed plate 12a. When the retainer 4 is moved relative to the outer cylinder 2 in direction B, the rolling elements 3 roll into the smaller diameter side of the wedge-shaped space S, and the clamping device 1 enters a clamped state. The load P acting on the shaft member 7 is transmitted to the fixed plate 12a via the rolling elements 3 and the outer cylinder 2. On the other hand, when the retainer 4 is moved relative to the outer cylinder 2 in direction A, the rolling elements 3 move to the larger diameter side of the wedge-shaped space S, and the clamping device 1 enters an unclamped state. (First embodiment)

[0018] Fig. 3 shows a workpiece holding device 11 according to a first embodiment of the present invention. Fig. 3(a) shows the state before holding the workpiece W, and Fig. 3(b) shows the state after holding the workpiece W. Note that Fig. 3 shows an example in which the workpiece holding device 11 is used as a vice for gripping and fixing the workpiece W, but the workpiece holding device 11 may also be incorporated into a robot to transport the workpiece W.

[0019] Reference numeral 12 denotes a pair of left and right main bodies, 7 denotes a shaft member, 1 denotes a clamping device, and 14 denotes a trigger mechanism. The main bodies 12, shaft member 7, clamping device 1, and trigger mechanism 14 are symmetrical. The configurations of the main body 12, shaft member 7, clamping device 1, and trigger mechanism 14 on the left side will be described below.

[0020] A plurality of shaft members 7, a plurality of clamping devices 1, and one trigger mechanism 14 are arranged in the main body 12. The number of shaft members 7 and clamping devices 1 is not particularly limited, and for example, four or more shaft members 7 may be arranged in a matrix on the main body 12.

[0021] The main body 12 is movably supported on a base 17. The main body 12 advances and retreats toward the workpiece W by a feed mechanism. The feed mechanism is not particularly limited, and for example, a feed screw, an air cylinder, or the like can be used. Figures 3(a) and (b) show a feed screw. The screw shaft 18 is formed with right-handed and left-handed threads. The main body 12 is provided with a ball screw nut (not shown) that screws into the right-handed and left-handed threads of the screw shaft. When the screw shaft 18 is rotated by a handle 20, a motor, or the like, the main body 12 advances and retreats toward the workpiece W due to the action of the ball screw.

[0022] The main body 12 includes a fixed plate 12a and a movable plate 12b. A retainer 4 of the clamp device 1 (see FIGS. 3(b) and 4(a) and 4(b)) is attached to the fixed plate 12a. An outer cylinder 2 of the clamp device 1 is attached to the movable plate 12b. The movable plate 12b is urged toward a lever 15 of the trigger mechanism 14 by a spring 5 of the clamp device 1 (see FIG. 1). Alternatively, the outer cylinder 2 may be attached to the fixed plate 12a, and the retainer 4 may be attached to the movable plate 12b. A spring (not shown) that urges the movable plate 12b toward the lever 15 may be provided between the fixed plate 12a and the movable plate 12b.

[0023] The shaft member 7 is supported by the main body 12 so as to be movable in the axial direction. A linear bearing (not shown), such as a ball bushing, is provided on the fixed plate 12a to guide the axial movement of the shaft member 7. A contactor 7a capable of coming into contact with the workpiece W is provided at the tip of the shaft member 7. The contactor 7a is not particularly limited and may be, for example, a pointed piece of rubber in a bullet or cone shape, a suction pad, or the like. A spring 19 (see FIG. 4(a)) is provided between the contactor 7a and the main body 12 to protrude the shaft member 7 from the main body 12.

[0024] As shown in FIG. 3(a), the trigger mechanism 14 includes a shaft-shaped trigger member 16 and a lever 15. The trigger member 16 and lever 15 are provided to switch the clamp device 1 between an unclamped state and a clamped state. The trigger member 16 is supported on the main body 12 so as to be movable in the axial direction. A linear bearing (not shown), such as a ball bushing, is provided on the fixed plate 12a to guide the axial movement of the trigger member 16. The tip 16a of the trigger member 16 is flange-shaped and can come into contact with the workpiece W. The position of the tip 16a of the trigger member 16 is determined to match the unevenness of the workpiece W. The rear end 16b of the trigger member 16 is flange-shaped and can come into contact with a return member 23. The return member 23 is attached to the base 17.

[0025] Lever 15 is connected to trigger member 16 so as to be tiltable around pivot 16c. Lever 15 changes the distance between fixed plate 12a and movable plate 12b as trigger member 16 moves relative to main body 12. Each lever 15 is, for example, L-shaped and has a short side portion 15a and a long side portion 15b (see FIG. 4(a)). The end of long side portion 15b is connected to trigger member 16 so as to be tiltable. Short side portion 15a is disposed between fixed plate 12a1 and movable plate 12b. A bearing 27 (see FIG. 4(a)) that contacts movable plate 12b and fixed plate 12a1 is provided on short side portion 15a. Note that the configuration of lever 15 is not limited to the above.

[0026] As shown in Figure 3(a), when the main body 12 moves to the initial position and the rear end 16b of the trigger member 16 comes into contact with the return member 23, the clamping device 1 switches from the clamped state to the unclamped state. As shown in Figure 3(b), when the main body 12 moves toward the workpiece W, the clamping device 1 is in the unclamped state, so the shaft member 7 follows the shape of the workpiece W. Preferably, the position of the shaft member 7 of each clamping device 1 is adjusted so that it comes into contact with the workpiece W before the trigger member 16 does.

[0027] As shown in Figure 3(b), when the main body 12 moves further toward the workpiece W and the tip 16a of the trigger member 16 comes into direct contact with the workpiece W, the trigger member 16 moves relative to the main body 12, and the clamping device 1 switches from the unclamped state to the clamped state. This fixes the shaft member 7, allowing the shaft member 7 to grip the workpiece W. Because the shaft member 7 follows the shape of the workpiece W when gripping it, it is possible to grip a wide variety of workpieces W.

[0028] 4(a) and (b) show enlarged views of the main body 12, the shaft member 7, and the trigger mechanism 14. FIG. 4(a) shows the unclamped state, and FIG. 4(b) shows the clamped state. As shown in FIG. 3(a), when the rear end 16b of the trigger member 16 contacts the return member 23, the trigger member 16 moves relative to the main body 12 by an amount δ to the right in FIG. 4(a), as shown in FIG. 4(a). As a result, the short side 15a of the lever 15 rotates so as to stand between the fixed plate 12a1 and the movable plate 12b, and the outer cylinder 2 moves relative to the retainer 4 to the left in FIG. 4(a). This switches the clamp device 1 from the clamped state to the unclamped state.

[0029] On the other hand, as shown in Fig. 3(b), when the tip 16a of the trigger member 16 comes into contact with the workpiece W, the trigger member 16 moves by an amount δ to the left in Fig. 4(b) relative to the main body 12, as shown in Fig. 4(b). As a result, the short side 15a of the lever 15 rotates so as to be inclined between the fixed plate 12a1 and the movable plate 12b, and the outer cylinder 2 moves to the right in Fig. 4(b) relative to the retainer 4. This switches the clamping device 1 from the unclamped state to the clamped state.

[0030] The above has described the configuration and operation of the workpiece holding device 11 of this embodiment. The workpiece holding device 11 of this embodiment has the following advantages.

[0031] When the trigger member 16 comes into direct contact with the workpiece W, the trigger member 16 moves relative to the main body 12, and the clamping device 1 switches from an unclamped state to a clamped state, so that the clamping device 1 can be switched from an unclamped state to a clamped state without using an air cylinder.

[0032] When the trigger member 16 comes into contact with the return member 23, the trigger member 16 moves relative to the main body 12, and the clamp device 1 switches from a clamped state to a non-clamped state, so that the clamp device 1 can be switched from a clamped state to a non-clamped state without using an air cylinder.

[0033] A pair of main bodies 12 are arranged to sandwich the workpiece W, so that a wide variety of workpieces W can be gripped. (Second embodiment)

[0034] 5 and 6 are perspective views of a workpiece holding device 41 according to a second embodiment of the present invention. Fig. 5 shows the initial position of the main body 42 (when the main body 42 is not gripping the workpiece W), and Fig. 6 shows the main body 42 gripping the workpiece W. The workpiece holding device 41 according to the second embodiment is attached to the tip shaft of a robot (not shown) and is used as a hand of the robot.

[0035] Reference numeral 43 denotes a base, 42 denotes a pair of left and right main bodies, 7 denotes a shaft member, and 51 denotes a trigger member. In the first embodiment, the clamping device 1 switches from an unclamped state to a clamped state when the trigger member 16 directly contacts the workpiece W. In contrast, in the second embodiment, as shown in FIG. 6, the clamping device 1 switches from an unclamped state to a clamped state when the trigger member 51 indirectly contacts the workpiece W via the contact 7a of the shaft member 7.

[0036] As shown in FIG. 5 , a pair of main bodies 42 are supported on a base 43 so as to be movable forward and backward relative to the workpiece W. The movement of the main bodies 42 is guided by a linear guide. The linear guide includes a rail 45 fixed to the base 43 and a block 46 fixed to the main bodies 42. A ball screw nut 47 is incorporated into the block 46. A screw shaft 48 having a right-handed thread and a left-handed thread is screwed into the ball screw nut 47. The rotation of the motor 44 is transmitted to the screw shaft 48 via a transmission means 49 such as a belt and pulley. When the screw shaft 48 rotates, the pair of main bodies 42 move forward and backward relative to the workpiece W.

[0037] Figure 7 shows the internal structure of the main body 42. Figure 7(a) shows the clamping device 1 in an unclamped state, and Figure 7(b) shows the clamping device 1 in a clamped state. As shown in Figure 7, the shaft member 7 and the trigger member 51 are incorporated into the main body 42.

[0038] FIG. 8 shows the main body 42 and the shaft member 7. The main body 42 includes fixed plates 42a and 42b and a movable plate 42c. The retainer 4 of the clamp device 1 (see FIGS. 1 and 8(b)) is attached to the fixed plate 42b. The outer cylinder 2 of the clamp device 1 is attached to the movable plate 42c. However, the movable plate 42c is not fixed to the outer cylinder 2, but merely contacts the flange 2c of the outer cylinder 2. This is to ensure concentricity between the outer cylinder 2 and the shaft member 7. The outer cylinder 2 is urged toward the movable plate 42c by the spring 5 of the clamp device 1 (see FIG. 1). The movable plate 42c is urged toward the lever 54 of the trigger mechanism 14 (see FIG. 7(a)) by the spring 5 of the clamp device 1.

[0039] 9(a), a linear bearing 52 such as a bushing is attached to the movable plate 42c. A shaft 53, into which the linear bearing 52 is inserted, is fixed to the fixed plates 42a and 42b. The movement of the movable plate 42c is guided by the linear bearing 52 and the shaft 53.

[0040] As shown in FIG. 8(a), the shaft member 7 is supported on the main body 42 so as to be movable in the axial direction. Linear bearings (not shown), such as ball bushings, are attached to the fixed plates 42a and 42b to guide the axial movement of the shaft member 7. The retainer 4 of the clamping device 1 is attached to the fixed plate 42b via these linear bearings. A contact 7a capable of contacting the workpiece W is provided at the tip of the shaft member 7. The contact 7a is not particularly limited and may be, for example, a pointed rubber piece shaped like a bullet or a cone, a suction pad, or the like. A spring 19 is provided between the contact 7a and the fixed plate 42a to protrude the shaft member 7 from the main body 42. The protruding state of the shaft member 7 is maintained when a stopper 7c at the rear end of the shaft member 7 abuts against the fixed plate 42b.

[0041] As shown in FIG. 9(a), the trigger member 51 includes a plate portion 51a and a shaft portion 51b fixed to the plate portion 51a. The plate portion 51a covers the workpiece W side of the main body 42 (see FIG. 5). The plate portion 51a has a through-hole 51a1 (see FIG. 5) through which the shaft member 7 is inserted. The diameter of the through-hole 51a1 is larger than the diameter of the spring 19 wound around the shaft member 7 and smaller than the diameter of the contact 7a. When the contact 7a comes into contact with the workpiece W and the shaft member 7 retracts, the rear end of the contact 7a comes into contact with the plate portion 51a (see FIG. 7(b)). The rear end 51b1 of the shaft portion 51b protrudes from the main body 42. The rear end 51b1 of the shaft portion 51b can come into contact with an angular returning member 43a (see FIG. 5) fixed to the base 43.

[0042] As shown in Figure 9(a), the trigger member 51 is supported by the main body 42 so as to be movable in the axial direction. A linear bearing 55 such as a bushing is fixed to a plate portion 51a of the trigger member 51. A shaft 56 to be inserted into the linear bearing 55 is fixed to the fixed plate 42a. In addition, a linear bearing (not shown) such as a bushing that guides the movement of the shaft portion 51b of the trigger member 51 is attached to the fixed plate 42a.

[0043] A lever 54 is connected to the shaft portion 51b so as to be tiltable around a pivot 51b2. The lever 54 is, for example, triangular in shape. Bearings 54a and 54b are provided at two corners of the lever 54 excluding the pivot 51b2. The lever 54 changes the distance between the fixed plate 42a and the movable plate 42c as the trigger member 51 moves relative to the main body 42.

[0044] FIG. 10 is a view taken along the arrow X in FIG. 5 and shows the main body 42 in an axial direction. As shown in FIG. 5, multiple shaft members 7 are arranged parallel to one another in the main body 42. As shown in FIG. 10, when viewed in the axial direction of the main body 42, the multiple shaft members 7 include a first shaft member 7-1 arranged at the vertices of a first regular hexagon h1 and a second shaft member 7-2 arranged at the vertices of a second regular hexagon h2, which has a side longer than that of the first regular hexagon h1 and is offset substantially 30° from the first regular hexagon h1. The two inner first shaft members 7-1 and the one outer second shaft member 7-2 form a triangle, preferably an equilateral triangle. The shaft portion 51b of the trigger member 51 and the lever 54 (see FIG. 9) are arranged inside the first regular hexagon h1. On the outside of the second regular hexagon h2, for example, four shafts 56 (see FIG. 9(a)) for guiding the trigger member 51 and for example, four shafts 53 (see FIG. 9(a)) for guiding the movable plate 42c are arranged. When viewed in the axial direction of the main body 42, the shafts 53 and 56 are arranged equidistant from two adjacent second shaft members 7-2.

[0045] The first shaft member 7-1 and the second shaft member 7-2 may be arranged at the vertices of a regular n-gon (n≧4), with the second regular n-gon h2 shifted by 180° / n with respect to the first regular n-gon h1. One or more shaft members 7 may be arranged inside the first regular n-gon h1, or one or more shaft members 7 may be arranged outside the second regular n-gon h2. Furthermore, the number of shafts 56 that guide the trigger member 51 may be three or less, and the number of shafts 53 that guide the movable plate 42c may be three or less.

[0046] The operation of the holding device 41 of the second embodiment will be described. As shown in Fig. 5, when the main body 42 is moved to the initial position by the motor 44, the rear end 51b1 of the shaft 51b of the trigger member 51 comes into contact with the return member 43a, the trigger member 51 moves to the initial position, and the clamping device 1 switches from the clamped state to the unclamped state.

[0047] 7(a), when the rear end 51b1 of the shaft 51b of the trigger member 51 comes into contact with the returning member 43a, the trigger member 51 moves rightward by an amount δ relative to the main body 42. This tilts the lever 54, widening the gap between the fixed plate 42a and the movable plate 42c, causing the outer cylinder 2 of the clamp device 1 to move leftward relative to the retainer 4, and the clamp device 1 switches from the clamped state to the unclamped state.

[0048] Next, when the motor 44 moves the main body 42 toward the workpiece W, the contact 7a of the shaft member 7 comes into contact with the workpiece W, and the shaft member 7 follows the shape of the workpiece W, as shown in Fig. 6. When the main body 42 moves further toward the workpiece W and the contact 7a of the shaft member 7 comes into contact with the trigger member 51, the trigger member 51 comes into contact with the workpiece W via the contact 7a, and the trigger member 51 moves relative to the main body 42. This switches the clamping device 1 from the unclamped state to the clamped state.

[0049] That is, as shown in Fig. 7(b), when the trigger member 51 moves leftward by an amount δ relative to the main body 42, the lever 54 tilts, and the movable plate 42c approaches the fixed plate 42a. As a result, the outer cylinder 2 of the clamping device 1 moves rightward in Fig. 7(b) relative to the retainer 4, and the clamping device 1 switches from the unclamped state to the clamped state. Since the one-way (leftward) movement of the shaft member 7 is limited by the clamping device 1, the workpiece W can be gripped by the shaft member 7.

[0050] As shown in Figure 6, when trigger member 51 is actuated and clamp device 1 switches from the unclamped state to the clamped state, the load on motor 44 increases, causing an increase in the current flowing through motor 44. Motor control device 61 (see Figure 5) stops motor 44 when the current flowing through motor 44 increases.

[0051] 5, the current flowing through the motor 44 is detected by a current sensor 62. The motor control device 61 includes a host controller 61a that issues commands to the motor 44 and a driver 61b that supplies power to the motor 44. The host controller 61a is a computer that includes a storage device that stores a program for controlling the motor 44, a RAM that stores current values, a processor that executes the program, etc. The host controller 61a stops the motor 44 when the current value detected by the current sensor 62 is equal to or greater than a threshold value.

[0052] The above has described the configuration and operation of the workpiece holding device 41 of the second embodiment. The workpiece holding device 41 of the second embodiment has the following advantages.

[0053] The trigger member 51 indirectly contacts the workpiece W via the contactor 7a of the shaft member 7, causing the trigger member 51 to move relative to the main body 42, and the clamping device 1 switches from the unclamped state to the clamped state. This makes it possible to switch the clamping device 1 from the unclamped state to the clamped state without using an air cylinder. Furthermore, because the trigger member 51 indirectly contacts the workpiece W via the contactor 7a, scratches on the workpiece W can be prevented.

[0054] Since the trigger member 51 has the plate portion 51a, the plate portion 51a can be pressed by the most retracted contactor 7a that comes into contact with the workpiece W, regardless of the protrusion of the workpiece W. Therefore, the trigger member 51 can be operated regardless of the shape of the workpiece W.

[0055] When viewed in the axial direction of the main body 42, the multiple shaft members 7 include a first shaft member 7-1 arranged at the vertex of a first regular n-gon h1 and a second shaft member 7-2 arranged at the vertex of a second regular n-gon h2, so that two adjacent inner first shaft members 7-1 and one outer second shaft member 7-2 can form a triangle, and the multiple shaft members 7 can be arranged in a densely packed state.

[0056] When viewed in the axial direction of the main body 42, the shaft portion 51b and the lever 54 are disposed inside the first regular n-gon h1, so that space can be used effectively and the main body 42 can be made compact.

[0057] When viewed in the axial direction of the main body 42, the axis 56 that guides the trigger member 51 and the axis 53 that guides the movable plate 42c are arranged outside the second regular n-gon h2, so that space can be used effectively and the main body 42 can be made compact.

[0058] A pair of main bodies 42 are arranged to sandwich the workpiece W, and the pair of main bodies 42 are driven by a motor 44, which is stopped when the current value of the motor 44 is equal to or greater than a threshold value, so the motor 44 can be controlled with the same program for both thin and thick workpieces W. By adjusting the threshold value according to the hardness of the workpiece W, both hard and soft workpieces can be gripped. (Third embodiment)

[0059] Figure 11 shows a workpiece holding device 71 according to a third embodiment of the present invention. Figure 11(a) shows the clamping device 1 in an unclamped state, similar to Figure 7(a), and Figure 11(b) shows the clamping device 1 in a clamped state, similar to Figure 7(b). The configurations of the main body, shaft member, clamping device, trigger member, and lever are the same as those of the second embodiment, so the same reference numerals are used and their description will be omitted.

[0060] In the second embodiment, the shaft 51b of the trigger member 51 comes into contact with the returning member 43a, causing the trigger member 51 to return to its initial position (see FIGS. 5 and 7(a)). In contrast, in the third embodiment, as shown in FIG. 11(a), the trigger member 51 is returned to its initial position by a spring 72.

[0061] The spring 72 is interposed between the fixed plate 42a of the main body 42 and the linear bearing 55. As shown in FIG. 11(b), when the main body 42 is moved away from the workpiece W while the clamping device 1 is in the clamped state, the contact 7a of the shaft member 7 is moved away from the plate portion 51a by the spring 19. As shown in FIG. 11(a), when the contact 7a is moved away from the plate portion 51a, the trigger member 51 is moved to the right by the spring 72 and returns to its initial position. This tilts the lever 54, and the clamping device 1 switches from the clamped state to the unclamped state.

[0062] According to the work holding device 71 of the third embodiment, the trigger member 51 is returned to its initial position by the spring 72, so there is no need to provide a horn-shaped return member 43a on the base 43, and the stroke can be easily changed by increasing the stroke of the main body 42 or changing the mounting position of the work holding device 71. (Fourth embodiment)

[0063] 12(a) and 12(b) show a workpiece holding device 21 according to a fourth embodiment of the present invention. FIG. 12(a) is a side view, and FIG. 12(b) is a bottom view. The workpiece holding device 21 according to the fourth embodiment is also attached to the tip shaft of a robot and used as a robot hand. A plurality of shaft members 7, a plurality of clamping devices 1, and a trigger mechanism 14 are arranged in a main body 22. A suction pad 7b is provided at the lower end of each vertically oriented shaft member 7 as a suction member for suctioning the workpiece W. The shaft members 7 are hollow and connected to a vacuum generator 26 via a flexible hose. As shown in FIG. 12(b), the shaft members 7 and the suction pads 7b are arranged in a matrix (vertical and horizontal) in the main body 22. The shaft members 7 are biased to a protruding state by a spring 25.

[0064] In the first embodiment, the trigger member 16 moves relative to the main body 12 when it comes into contact with the return member 23, and the clamp device 1 switches from the clamped state to the unclamped state (see FIG. 3(a)). In contrast, in the fourth embodiment, the trigger member 16 moves relative to the main body 22 due to the spring 24 that biases the trigger member 16 to the protruding state, and the clamp device 1 switches from the clamped state to the unclamped state.

[0065] Reference numeral 22 denotes a main body, 22a denotes a fixed plate, and 22b denotes a movable plate. A ball bushing (not shown) that guides the movement of the shaft member 7 is attached to the fixed plate 22a. A retainer 4 of the clamp device 1 is fixed to the fixed plate 22a via the ball bushing (not shown). An outer cylinder 2 of the clamp device 1 is attached to the movable plate 22b. The configuration of the clamp device 1 is the same as that of the clamp device 1 of the first embodiment.

[0066] Reference numeral 16 denotes a trigger member, and 15 denotes a lever. A tip 16a of the trigger member 16 is flange-shaped and can come into contact with the workpiece W. The lever 15 is disposed between a fixed plate 22a and a movable plate 22b. A spring 24 that biases the trigger member 16 to a protruding state is provided between the tip 16a of the trigger member 16 and the fixed plate 22a. As in the second embodiment, the tip 16a of the trigger member 16 may be made into a plate shape of approximately the same size as the main body 22, and a through hole through which the shaft member 7 is inserted may be formed in the plate-shaped tip 16a, so that the suction pad 7b comes into contact with the tip 16a.

[0067] Fig. 12(a) shows the clamping device 1 in an unclamped state, and Fig. 13 shows the clamped state. When the clamping device 1 is in an unclamped state as shown in Fig. 12(a), as the main body 22 descends toward the workpiece W, the suction pad 7b of the shaft member 7 comes into contact with the workpiece W, and the shaft member 7 follows the shape of the workpiece W against the spring force of the spring 25, as shown in Fig. 13.

[0068] As the main body 22 continues to descend toward the workpiece W, the tip 16a of the trigger member 16 comes into contact with the workpiece W, and the trigger member 16 rises against the spring force of the spring 24. At this time, as shown in FIG. 13, the short side 15a of the lever 15 rotates so as to be inclined between the fixed plate 22a and the movable plate 22b, the outer cylinder 2 rises relative to the retainer 4, and the clamping device 1 switches from the unclamped state to the clamped state. If the suction pad 7b is evacuated while the shaft member 7 is fixed by the clamping device 1, the workpiece W can be grasped.

[0069] On the other hand, when the vacuum of the suction pad 7b is released and the main body 22 is moved away from the workpiece W, the trigger member 16 returns to the initial position shown in Figure 12(a) due to the biasing force of the spring 24. At this time, the short side 15a of the lever 15 rotates so as to stand between the fixed plate 22a and the movable plate 22b, the outer cylinder 2 descends relative to the retainer 4, and the clamping device 1 switches from the clamped state to the unclamped state.

[0070] According to the fourth embodiment, the following effects are achieved.

[0071] When the trigger member 16 comes into contact with the workpiece W, the trigger member 16 moves relative to the main body 22, and the clamping device 1 switches from an unclamped state to a clamped state, so that the clamping device 1 can be switched from an unclamped state to a clamped state without using an air cylinder.

[0072] The spring 24 returns the trigger member 16 to its initial position, so that the clamping device 1 can be switched from the clamped state to the unclamped state without using an air cylinder.

[0073] The shaft member 7 is hollow and has a suction pad 7b at the tip thereof, so that the workpiece W can be sucked. (Fifth embodiment)

[0074] 14(a) and (b) show a workpiece holding device 31 according to a fifth embodiment of the present invention. FIG. 14(a) is a side view, and FIG. 14(b) is a bottom view. In the fifth embodiment, similar to the fourth embodiment, a plurality of shaft members 7, a plurality of clamping devices 1, and a trigger mechanism 14 are arranged in a main body 32. A suction pad 7b is provided at the tip of each shaft member 7 as a suction member for suctioning the workpiece W. The shaft members 7 are hollow and connected to a vacuum generator 26. The configurations of the shaft members 7, the trigger mechanism 14, and the vacuum generator 26 are the same as those in the fourth embodiment, so the same reference numerals are used and their description will be omitted.

[0075] In the fourth embodiment, one clamp device 1 is provided for each shaft member 7 to restrict the movement of the shaft member 7 in one direction (1-way), whereas in the fifth embodiment, two clamp devices 1 are provided for each shaft member 7 to restrict the movement of the shaft member 7 in both directions (2-way).

[0076] The main body 32 includes two movable plates 32b and two fixed plates 32a. A retainer 4 of the clamp device 1 is fixed to each fixed plate 32a via a ball bushing (not shown). An outer cylinder 2 of the clamp device 1 is attached to each movable plate 32b. The two clamp devices 1 arranged on each shaft member 7 are arranged so that the large diameter portions of their wedge-shaped spaces face each other. The configuration of the clamp device 1 itself is the same as that of the clamp device 1 of the first embodiment, so the same reference numerals are used and a description thereof will be omitted.

[0077] The lever 15 of the trigger mechanism 14 is disposed between the two movable plates 32b. Fig. 14(a) shows the unclamped state, and Fig. 15 shows the clamped state. In the unclamped state as shown in Fig. 14(a), when the main body 32 descends toward the workpiece W, the suction pad 7b of the shaft member 7 comes into contact with the workpiece W, and the shaft member 7 follows the shape of the workpiece W against the spring force of the spring 25, as shown in Fig. 15.

[0078] As the main body 32 continues to descend toward the workpiece W, the tip 16a of the trigger member 16 comes into contact with the workpiece W, and the trigger member 16 rises relative to the main body 32 against the spring force of the spring 24. At this time, as shown in FIG. 15, the short side 15a of the lever 15 rotates so as to be inclined between the two movable plates 32b, the two outer cylinders 2 approach each other, and the clamping device 1 switches from the unclamped state to the clamped state. If the suction pad 7b is evacuated while the shaft member 7 is fixed by the clamping device 1, the workpiece W can be grasped.

[0079] On the other hand, when the vacuum of the suction pad 7b is released and the main body 32 is moved away from the workpiece W, the trigger member 16 returns to the return position shown in Fig. 14(a) due to the biasing force of the spring 24. At this time, as shown in Fig. 14(a), the short side portion 15a of the lever 15 rotates so as to stand between the two movable plates 32b, the two outer cylinders 2 move away from each other, and the clamping device 1 switches from the clamped state to the unclamped state.

[0080] According to the fifth embodiment, in addition to achieving the same effects as the fourth embodiment, two clamping devices 1 are provided for each shaft member 7, restricting the movement of the shaft member 7 in both directions (2-way), thereby achieving the effect of stably gripping the workpiece W. (Sixth embodiment)

[0081] 16(a) and (b) show a workpiece holding device 81 according to a sixth embodiment of the present invention. FIG. 16(a) is a side view, and FIG. 16(b) is a bottom view. In the sixth embodiment, a plurality of shaft members 7 and a plurality of clamping devices 1 are arranged in a main body 32. A suction pad 7b for adsorbing a workpiece W is provided at the tip of each shaft member 7. The shaft members 7 are hollow and connected to a vacuum generator (not shown). Two clamping devices 1 are provided on each shaft member 7, restricting the movement of each shaft member 7 in both directions (two-way). The configurations of the main body 32, shaft members 7, and clamping devices 1 are the same as those in the fifth embodiment, so the same reference numerals are used and their description will be omitted.

[0082] The distance between the two movable plates 32b is adjusted by a cylinder device 85 such as an air cylinder. A main body 85a of the cylinder device 85 is attached to the upper movable plate 32b. A rod 85b of the cylinder device 85 is attached to the lower movable plate 32b. As shown in FIG. 16(a), when the distance between the two movable plates 32b is widened by the cylinder device 85, the clamp device 1 is put into an unclamped state. As shown in FIG. 17, when the distance between the two movable plates 32b is narrowed by the cylinder device 85, the clamp device 1 is put into a clamped state.

[0083] As shown in FIG. 16(b), when viewed in the axial direction of the main body 32, the multiple shaft members 7 include a first shaft member 7-1 disposed at the vertices of a first regular hexagon h1, and a second shaft member 7-2 disposed at the vertices of a second regular hexagon h2, which has a side longer than that of the first regular hexagon h1 and is offset substantially 30° from the first regular hexagon h1. A cylinder device 85 (see FIG. 16(a)) is disposed inside the first regular hexagon h1. Four shafts 84, for example, that guide the movable plate 32b are disposed outside the second regular hexagon h2. The shafts 84 are disposed equidistant from two adjacent second shaft members 7-2. Linear bearings 83, such as bushings, into which the shafts 84 are inserted are attached to the movable plate 32b.

[0084] Alternatively, the first shaft member 7-1 and the second shaft member 7-2 may be disposed at the vertices of a regular n-gon (n≧4), and the second regular n-gon h2 may be shifted by 180° / n with respect to the first regular n-gon h1.

[0085] The operation of the workpiece holding device 81 of the sixth embodiment will now be described. In the unclamped state shown in Fig. 16(a), when the main body 32 is brought close to a workpiece (not shown), the suction pad 7b of the shaft member 7 comes into contact with the workpiece and follows the shape of the workpiece, as shown in Fig. 17. The cylinder device 85 is operated to switch the clamping device 1 from the unclamped state to the clamped state, and a vacuum is created on the suction pad 7b, allowing the workpiece to be adsorbed.

[0086] The workpiece holding device 81 of the sixth embodiment has the following advantages.

[0087] When viewed in the axial direction of the main body 32, the multiple shaft members 7 include a first shaft member 7-1 arranged at the vertex of a first regular n-gon h1 and a second shaft member 7-2 arranged at the vertex of a second regular n-gon h2, so that two adjacent inner first shaft members 7-1 and one outer second shaft member 7-2 can form a triangle, and the multiple shaft members 7 can be arranged in a densely packed state.

[0088] When viewed in the axial direction of the main body 32, the cylinder device 85 is disposed inside the first regular n-gon h1, so that space can be used effectively and the main body 32 can be made compact.

[0089] When viewed in the axial direction of the main body 32, the shaft 84 that guides the movable plate 32b is disposed outside the second regular n-gon h2, so that space can be used effectively and the main body 32 can be made compact. [Explanation of symbols]

[0090] 1... clamping device, 7... shaft member, 7a... contactor (part of shaft member), 7b... suction pad (suction member), 7-1... first shaft member, 7-2... second shaft member, 11, 21, 31, 41, 71, 81... work holding device, 12, 22, 32, 42... main body, 16, 51... trigger member, 32b, 42c... movable plate, 44... motor, 51a... plate portion, 53, 84... shaft for guiding movable plate, 56... shaft for guiding trigger member, 61... motor control device, 85... cylinder device, W... work, h1... first regular hexagon, h2... second regular hexagon

Claims

1. The main body and A plurality of shaft members that can come into contact with the workpiece; a plurality of clamping devices attached to the main body, into which the plurality of shaft members are inserted, and which are switchable between an unclamped state in which the shaft members are released and a clamped state in which axial movement of the shaft members is restricted, When viewed in the axial direction of the main body, the plurality of shaft members include first shaft members arranged at vertices of a first regular n-gon, and second shaft members arranged at vertices of a second regular n-gon having one side longer than that of the first regular n-gon and shifted substantially by 180° / n with respect to the first regular n-gon, Each shaft member is inserted into each clamping device, A workpiece holding device that grips a workpiece without the shaft members coming into contact with each other. However, n is an integer of 4 or greater.

2. 2. The workpiece holding device according to claim 1, wherein, when viewed in the axial direction of the main body, at least a part of a trigger member or a cylinder device for switching the clamping device between the unclamped state and the clamped state is arranged inside the first regular n-gon.

3. 3. The workpiece holding device according to claim 1, wherein, when viewed in the axial direction of the main body, an axis for guiding a trigger member for switching the clamping device between the unclamped state and the clamped state is arranged on the outside of the second regular n-gon.

4. The pair of main bodies are arranged to sandwich the workpiece, The workpiece holding device according to any one of claims 1 to 3, characterized in that it comprises a motor that moves the main body forward and backward relative to the workpiece, and a motor control device that stops the motor when a current value of the motor becomes equal to or greater than a threshold value.

5. 4. The workpiece holding device according to claim 1, wherein the shaft member is hollow and has a suction member at the tip thereof for suctioning the workpiece.

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