Gripping device

Abstract

A gripping device (6) according to the present disclosure comprises: a plurality of claw portions (24) for gripping or releasing a workpiece (W); a gripping portion (22) for moving the claw portions (24) in an opening / closing direction; and a rotational transmission mechanism (32) for rotating the workpiece (W) gripped by the claw portions (24) about a rotational axis (X1) parallel to the opening / closing direction. The rotational transmission mechanism (32) includes: rotating portions (34) that are attached to each claw portion (24), move in the opening / closing direction together with the claw portions (24), and can rotate around the rotational axis (X1) relative to the claw portions (24); a second drive source (36) that rotationally drives the rotating portions (34); a power transmission mechanism that is connected to the rotating portions (34), moves in the opening / closing direction together with the rotating portions (34), and transmits power of the second drive source (36) to the rotating portions (34); and an extension / retraction rotation mechanism (37) that can extend and retract in the opening / closing direction and that transmits the rotation of the second drive source (36) to the power transmission mechanism (35).

Description

gripping device Related Applications

[0001] This application claims priority to Japanese Patent Application Nos. 2024-042354 and 2024-042356, filed March 18, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a gripping device for gripping a workpiece such as a mechanical part or an electronic part.

[0003] In a hand installed at the tip of a multi-joint robot or the like, the claws are opened and closed in a linear direction to grasp a workpiece, and the posture of the workpiece can be changed while it is being grasped by the claws (for example, Patent Documents 1 and 2).

[0004] Patent No. 5617512 Patent No. 6029561

[0005] The hand of Patent Document 1 has a rotatable nut attached to a shaft extending in the opening and closing direction of the jaws, and rotation is transmitted to the jaws via the nut, causing the jaws to oscillate while gripping a workpiece. The hand of Patent Document 2 has a nut threadedly engaged with a ball screw extending in the opening and closing direction of the jaws, and rotation is transmitted to the jaws via the nut, causing the jaws to oscillate while gripping a workpiece. In this way, the hands of Patent Documents 1 and 2 integrate a mechanism for gripping a workpiece with a mechanism for changing the posture of the gripped workpiece. Therefore, for example, if the height of the workpiece to be gripped changes during a setup change, it is not possible to easily change the length from the base of the jaws to the oscillating rotation axis.

[0006] An object of the present invention is to provide a gripping device that can easily change the length from the base of the jaws to the oscillating rotation axis even when the height of the workpiece to be gripped is different during setup change.

[0007] a gripping device according to a first configuration of the present invention, comprising: a plurality of claws for gripping or releasing a workpiece; a gripping unit for moving the claws in a gripping direction to grip the workpiece and a release direction to release the workpiece; and a rotation transmission mechanism for rotating the workpiece gripped by the claws around a rotation axis parallel to the gripping direction and the release direction, wherein the gripping unit has a gripping mechanism to which the claws are attached and which moves in the gripping direction and the release direction, and a first drive source for moving the gripping mechanism in the gripping direction and the release direction, and the rotation transmission mechanism comprises: a rotating unit attached to each of the plurality of claws, which moves together with the claws in the gripping direction and the release direction and is rotatable around the rotation axis relative to the claws; a second drive source for driving the rotating unit to rotate around the rotation axis; and a power transmission mechanism connected to at least one of the rotating units, which moves together with the rotating unit in the gripping direction and the release direction, and which transmits power of the second drive source to the rotating unit; The gripping mechanism has an extendable and retractable rotation mechanism that is extendable in the gripping direction and the releasing direction and that transmits the rotation of the second drive source to the power transmission mechanism.

[0008] According to this configuration, a rotating unit of the rotation transmission mechanism is separately provided at the tip of the claw attached to the gripping mechanism of the gripping unit, and the rotating unit rotates the workpiece around a rotation axis parallel to the gripping and release directions of the claw. The gripping mechanism moves using power from a first drive source, and the rotating unit rotates using power from a second drive source. In other words, the gripping mechanism and the rotating unit are provided independently. As a result, even if the height of the workpiece to be gripped changes during a setup change, it is sufficient to replace the claw and the rotation transmission mechanism supported by it, and there is no need to change the gripping unit. As a result, the length from the base of the claw to the rotation axis can be easily changed.

[0009] In addition, the second drive source does not move in the gripping direction or the release direction together with the gripping mechanism of the gripping unit. Therefore, the load in the gripping direction and the release direction is reduced, allowing the gripping mechanism to operate at high speed. Furthermore, since only the rotating unit is rotated, rather than the entire gripping unit, the only rotating objects are the workpiece and the rotating unit, reducing the weight and moment of inertia of the rotating objects. As a result, high-speed rotation of the rotating unit and low torque of the second drive source are possible, allowing for a smaller and lighter second drive source.

[0010] In the first configuration of the present invention, the rotation transmission mechanism and the claw portion may be integrated to form a sub-assembly, and the sub-assembly may be attached to the gripping portion. Specifically, the rotating portion, the claw portion, the power transmission mechanism, the telescopic rotation mechanism, and the second drive source are integrated. With this configuration, the claw portion having the rotation transmission mechanism can be applied to existing gripping portions. In particular, it is highly versatile because it can easily be adapted to the size of the gripping mechanism and the length of the claw portion.

[0011] In the first configuration of the present invention, the telescopic rotation mechanism may include a first rotating shaft connected to the output shaft of the second drive source, a second rotating shaft connected to an inlet rotating body of the power transmission mechanism, and an telescopic rotation structure that transmits rotation of the first rotating shaft to the second rotating shaft and supports the second rotating shaft so that it can move relative to the first rotating shaft in the gripping direction and the release direction.

[0012] In this case, the telescopic rotating structure may include a cylindrical outer member provided at one end of the first rotating shaft and the second rotating shaft, an inner member provided at the other end of the first rotating shaft and the second rotating shaft and inserted into a hollow hole in the outer member, and rolling elements interposed between the outer member and the inner member to transmit rotation of the outer member to the inner member and to support the member provided on the second rotating shaft so that it can move in the gripping direction and the releasing direction relative to the member provided on the first rotating shaft. With this configuration, rotational torque can be reliably transmitted in the rotational direction, and smooth movement with little resistance in the telescopic direction is possible.

[0013] Alternatively, the telescopic rotation structure may have a first gear provided on one of the first rotation shaft and the second rotation shaft, the first gear having an axial dimension longer than the opening / closing width of the gripping mechanism, and a second gear provided on the other of the first rotation shaft and the second rotation shaft, meshing with the first gear to transmit the rotation of the first gear and movable in the gripping direction and the release direction relative to the first gear. With this configuration, with a small number of parts, rotational torque can be reliably transmitted in the rotation direction and movement in the telescopic direction is possible.

[0014] In the first configuration of the present invention, the second drive source may be a motor. With this configuration, the orientation of the workpiece can be easily changed to any inclination.

[0015] In the first configuration of the present invention, the power transmission mechanism may have a belt-shaped endless power transmission member. The belt-shaped endless power transmission member may be, for example, a timing belt or a drive chain. With this configuration, the length from the second drive source to the rotating part can be easily changed, thereby increasing the degree of freedom in the arrangement of the second drive source.

[0016] In the first configuration of the present invention, the power transmission mechanism may have a rod with bevel gears at both ends. With this configuration, the length from the second drive source to the rotating part can be easily changed, thereby increasing the degree of freedom in arranging the second drive source.

[0017] In the first configuration of the present invention, the power transmission mechanism may have a plurality of spur gears. With this configuration, the number and diameter of the spur gears can be changed to adjust the rotation speed of the rotating part and the distance to the rotating part, thereby increasing the degree of freedom in the capacity, arrangement, etc. of the second drive source.

[0018] A gripping device according to a second aspect of the present invention includes a plurality of claws for gripping or releasing a workpiece, a gripping unit that moves the claws in a gripping direction to grip the workpiece and a release direction to release the workpiece, and a rotation transmission mechanism that rotates the workpiece gripped by the claws around a rotation axis parallel to the gripping direction and the release direction. The gripping unit includes a gripping mechanism to which the claws are attached and which moves in the gripping direction and the release direction, and a first drive source that moves the gripping mechanism in the gripping direction and the release direction. The rotation transmission mechanism includes a rotating unit attached to each of the plurality of claws and rotatable about the rotation axis relative to the claws, and a second drive source attached to at least one of the claws and driving the rotating unit to rotate about the rotation axis. The rotation transmission mechanism moves together with the claws in the gripping direction and the release direction.

[0019] According to this configuration, a rotating unit of the rotation transmission mechanism is separately provided at the tip of the claw attached to the gripping mechanism of the gripping unit, and the rotating unit rotates the workpiece around a rotation axis parallel to the gripping and release directions of the claw. The gripping mechanism moves using power from a first drive source, and the rotating unit rotates using power from a second drive source. In other words, the gripping mechanism and the rotating unit are provided independently. As a result, even if the height of the workpiece to be gripped changes during a setup change, it is sufficient to replace the claw and the rotation transmission mechanism supported by it, and there is no need to change the gripping unit. As a result, the length from the base of the claw to the rotation axis can be easily changed.

[0020] In the second configuration of the present invention, the second drive source may be a motor. With this configuration, the orientation of the workpiece can be easily changed to any desired inclination.

[0021] In the second configuration of the present invention, the rotation transmission mechanism may further include a power transmission mechanism that transmits power from the second drive source to the rotating unit, and the rotation axis of the second drive source may be perpendicular to the rotation axis of the rotating unit. In this case, the power transmission mechanism may be, for example, a bevel gear. With this configuration, the amount of protrusion of the second drive source in the gripping direction or the release direction can be reduced.

[0022] In the second configuration of the present invention, the rotation transmission mechanism may further include a power transmission mechanism that transmits power from the second drive source to the rotating unit, and the rotation axis of the second drive source may be offset parallel to the rotation axis of the rotating unit. With this configuration, the second drive source can be disposed on the inside in the gripping direction or the release direction, thereby reducing the amount by which the second drive source protrudes in the gripping direction or the release direction.

[0023] In this case, the power transmission mechanism may be a belt-shaped endless power transmission member, such as a timing belt. With this configuration, the second drive source can be disposed away from the rotating part, thereby increasing the degree of freedom in the placement of the second drive source.

[0024] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

[0025] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present invention. The scope of the present invention is defined by the appended claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same or corresponding parts.

[0023] Figure 1 is a perspective view showing a picking system equipped with a gripping device according to a first embodiment of the present invention.

[0024] Figure 2 is a front view showing the gripping device.

[0025] Figure 3 is a side view of the gripping device of Figure 2A seen from direction IIB.

[0026] Figure 4 is a longitudinal sectional view of the gripping device.

[0027] Figure 5 is a perspective view showing the telescopic rotation mechanism of the gripping device.

[0028] Figure 6 is a side view showing the telescopic rotation mechanism.

[0029] Figure 7 is a sectional view taken along line IVC-IVC of Figure 4B.

[0030] Figure 8 is a front view showing a modified telescopic rotation mechanism of the gripping device.

[0031] Figure 9 is a front view showing a first modified example of the gripping device.

[0032] Figure 10 is a front view showing a second modified example of the gripping device.

[0033] Figure 11 is a front view showing a third modified example of the gripping device.

[0034] Figure 12 is a side view showing the gripping device.

[0035] Figure 13 is a front view showing a fourth modified example of the gripping device.

[0036] Figure 14 is a front view showing an enlarged claw portion of the gripping device.

[0037] Figure 15 is a side view showing another picking system equipped with the gripping device according to the first embodiment of the present invention. FIG. 13A is a perspective view showing a gripping device according to a second embodiment of the present invention. FIG. 14 is a front view showing a gripping device according to a third embodiment of the present invention. FIG. 15A is a side view of the gripping device of FIG. 13A, seen from the XIIIB direction. FIG. 16 is a longitudinal sectional view showing the gripping device. FIG. 17 is a front view showing a first modified example of the gripping device. FIG. 18 is a side view of the gripping device, seen from the XVB direction of FIG. 15A. FIG. 19 is a front view showing a second modified example of the gripping device. FIG. 20 is a front view showing a third modified example of the gripping device. FIG. 21 is a front view showing a fourth modified example of the gripping device. FIG. 22 is a perspective view showing a gripping device according to a fourth embodiment of the present invention. FIG. 23 is a perspective view showing a picking system including a conventional gripping device. FIG. 24 is a perspective view showing an inversion process of inverting a workpiece in the picking system. FIG. 25 is a side view showing another picking system including a conventional gripping device. FIG. 26 is an enlarged side view showing the gripping device of the picking system.

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. In the following description, Fig. 1 is a perspective view showing a picking system SY equipped with a gripping device according to a first embodiment of the present invention.

[0027] 1 , a picking system SY uses a robot 4 and a hand 6, which is a type of gripping device, to pick up workpieces W transported by a first conveyor 2 and supply them to a second conveyor 3 for the next process. In detail, the picking system SY includes a first conveyor 2 that transports the workpieces W, a robot 4 that transports the workpieces W from the first conveyor 2 to the second conveyor 3, and a hand 6 attached to the tip of an arm 10 of the robot 4. The hand 6 of the present invention aligns the orientation of the workpieces W when placing them on the second conveyor 3.

[0028] In this embodiment, the workpiece W is a rectangular plate-shaped member. However, the workpiece W is not limited to this and may be, for example, a mechanical part, an electronic part, a plastic part, a drug, a medical product, a food product, a miscellaneous item, etc. In the following description, "F" on the workpiece W represents the front side, and "B" represents the back side.

[0029] The first conveyor 2, second conveyor 3, robot 4, and hand 6 are synchronously controlled by a control device 12. Specifically, the position and orientation of the workpiece W on the first conveyor 2 is detected by a workpiece detection means (not shown), the arm 10 of the robot 4 moves to the detected position, and the hand 6 grips the workpiece W at an angle corresponding to the detected orientation. Furthermore, after aligning the orientation of the workpiece W, the arm 10 of the robot 4 moves to the second conveyor 3, and the hand 6 releases the workpiece W. This operation is then repeated.

[0030] [Robot] The robot 4 of this embodiment is an articulated robot having multiple arms 10 that rotate around multiple rotation axes. The robot 4 moves back and forth between the first conveyor 2 and the second conveyor 3. The robot 4 of this embodiment has a base 20 fixed to the floor surface and three arms, first to third, 10A, 10B, and 10C.

[0031] The base 20 is a cylindrical member with its axis AX1 extending vertically. The base 20 is connected to the floor surface so as to be rotatable about a first axis of rotation AX1. In this embodiment, the first axis of rotation AX1 coincides with the axis AX1 of the base 20.

[0032] The first arm 10A is a rod-shaped member extending linearly, and its base end 10Aa is connected to the upper part of the base unit 20 so as to be rotatable about a second horizontal rotation axis AX2. The second arm 10B is a rod-shaped member extending linearly, and its base end 10Ba is connected to the tip end 10Ab of the first arm 10A so as to be rotatable about a third horizontal rotation axis AX3. The second arm 10B is rotatable about a fourth horizontal rotation axis AX4 relative to the tip end 10Ab of the first arm 10A.

[0033] The third arm 10C is a linearly extending rod-shaped member that is connected to the tip 10Bb of the second arm 10B so as to be rotatable about a horizontal fifth axis of rotation AX5. The third arm 10C is rotatable about a vertical sixth axis of rotation AX6 relative to the tip 10Bb of the second arm 10B. The hand 6 is attached to the lower end 10Ca of the third arm 10C.

[0034] The base 20 and each of the arms 10A, 10B, and 10C are driven by an actuator (not shown). The actuator is, for example, an electric motor, but is not limited to this. In this embodiment, the robot 4 is fixed to the floor surface, but it does not have to be fixed. Furthermore, the structure of the robot 4 is not limited to this embodiment, and any working robot can be applied.

[0035] 2A and 2B, the configuration of the hand 6 will be described. As described above, the hand 6 is a type of gripping device that grips the workpiece W. The hand 6 picks up the workpiece W on the first conveyor 2 (FIG. 1) and places the workpiece W on the second conveyor 3 (FIG. 1). As shown in FIG. 2A, the hand 6 has a plurality of claws 24 that grip or release the workpiece W, and a gripping unit 22 that moves the claws 24 in a gripping direction D1 to grip the workpiece W and in a release direction to release the workpiece W.

[0036] The gripping unit 22 has a gripping mechanism 26 to which the claws 24 are attached and which moves in a gripping direction D1 and a release direction D2, and a first drive source 28 that moves the gripping mechanism 26 in the gripping direction D1 and the release direction D2. In detail, the gripping unit 22 has a box-shaped gripping unit main body 30, and the first drive source 28 is housed inside the gripping unit main body 30.

[0037] The gripping mechanisms 26 are provided to protrude from the gripping body 30, and move relative to the gripping body 30 in the gripping direction D1 and the releasing direction D2 by the power of the first drive source 28. In this embodiment, two gripping mechanisms 26 are provided. The number of gripping mechanisms 26 is not limited to this, and may be, for example, three or more.

[0038] In this embodiment, the gripping mechanism 26 closes (moves in the closing direction) to grip the workpiece W with the claws 24. That is, in this embodiment, the gripping direction D1 for gripping the workpiece W is the closing direction, and the release direction D2 for releasing the workpiece W is the opening direction. In the following description, the gripping direction D1 is referred to as the closing direction D1, the release direction D2 is referred to as the opening direction, and the "gripping direction and release direction" are referred to as the "opening / closing direction."

[0039] The first drive source 28 is, for example, an air cylinder driven by compressed air. However, the first drive source 28 is not limited to this and may be a hydraulic actuator, an electric motor, or the like. In this embodiment, one first drive source 28 drives two gripping mechanisms 26. However, a first drive source 28 may be provided for each gripping mechanism 26.

[0040] The hand 6 further includes a rotation transmission mechanism 32 that rotates the workpiece W. The rotation transmission mechanism 32 rotates the workpiece W gripped by the claws 24 about a rotation axis X1 that is parallel to the opening and closing direction. The rotation transmission mechanism 32 includes a rotating unit 34 that can rotate about the rotation axis X1 relative to the claws 24, and a second drive source 36 that drives the rotating unit 34 to rotate about the rotation axis X1.

[0041] The rotation transmission mechanism 32 further includes a power transmission mechanism 35 that transmits the power of the second drive source 36 to the rotating unit 34, and an extendable rotation mechanism 37 that transmits the rotation of the second drive source 36 to the power transmission mechanism 35. In other words, the rotation of the second drive source 36 is transmitted to the rotating unit 34 via the extendable rotation mechanism 37 and the power transmission mechanism 35.

[0042] In this embodiment, the second drive source 36 is a motor. The second drive source 36 is not limited to a motor, and may be, for example, a structure that uses a spring to rotate mechanically, a structure that uses air pressure such as an air cylinder, or a structure that uses hydraulic pressure such as a hydraulic actuator. When a motor is used as the second drive source 36, the orientation of the workpiece W can be easily changed to any inclination compared to air pressure or hydraulic pressure.

[0043] Furthermore, the first drive source 28 and the second drive source 36 may have different structures, such as a structure in which the first drive source 28 uses air pressure and a structure in which the second drive source 36 uses electricity, or may have the same structure. Furthermore, in this embodiment, the power of the second drive source 36 is supplied to only one of the two claws 24, but it may also be supplied to both.

[0044] The second drive source 36 is fixed to the gripping unit main body 30 of the gripping unit 22 and does not move in the opening / closing direction together with the gripping mechanism 26. Moreover, because the second drive source 36 does not move in the opening / closing direction together with the gripping mechanism 26 of the gripping unit 22, the load in the opening / closing direction is reduced. This allows the gripping mechanism 26 to operate at high speed. Furthermore, because the objects rotated by the power of the second drive source 36 are only the workpiece W and the rotating unit 34, the moment of inertia is reduced, allowing for high-speed rotation.

[0045] The rotating unit 34 is attached to each of the plurality of claws 24 and moves in the opening and closing direction together with the claws 24. In this embodiment, the rotating unit 34 is provided at the tip of the claw 24. As shown in FIG. 3 , the rotating unit 34 has a disk-shaped rotating unit main body 38 and a shaft 40 extending in the opening direction from the end face of the rotating unit main body 38. The center line of the rotating unit main body 38 and the central axis of the shaft 40 coincide with each other. Furthermore, the central axes of the pair of rotating units 34, 34 in this embodiment coincide with each other.

[0046] The rotating part 34 in this embodiment is made of metal. However, the material of the rotating part 34 is not limited to this and may be made of resin, for example. Furthermore, a rubber sheet, rubber bumps, or the like may be provided on the gripping surface 34a of the rotating part 34 that faces the closing direction of the rotating part main body 38. This makes it possible to prevent the workpiece W from slipping when gripping the workpiece W or when rotating the gripped workpiece W.

[0047] A through hole 24a facing the opening / closing direction is provided at the tip of the claw portion 24. In this embodiment, the shaft 40 of the rotating portion 34 is inserted into this through hole 24a via a rolling bearing 42. This allows the rotating portion 34 to be rotatably supported by the claw portion 24. The axis of the through hole 24a coincides with the central axis of the rotating portion 34. In other words, the axis of the through hole 24a coincides with the rotation axis X1 of the rotating portion 34. In this embodiment, a rolling bearing 42 is used, but a bearing other than a rolling bearing may also be used, such as a plain bearing.

[0048] As shown in FIG. 2A , a power transmission mechanism 35 is connected to the tip of the shaft 40 of one of the rotating units 34. The power transmission mechanism 35 is coupled to the rotating unit 34 and moves together with the rotating unit 34 in the gripping direction D1 and the releasing direction D2. A retaining member 45 is attached to the tip of the shaft 40 of the other rotating unit 34, to which the second drive source 36 is not connected. The retaining member 45 is, for example, a nut. In this embodiment, the power transmission mechanism 35 is coupled to one of the rotating units 34. However, the power transmission mechanism 35 may be coupled to at least one rotating unit 34, or may be coupled to multiple rotating units 34. In this embodiment, a belt-shaped endless power transmission member 50, specifically a timing belt, is used as the power transmission mechanism 35. The endless power transmission member 50 may also be a drive chain.

[0049] The timing belt 50 is provided between the telescopic rotation mechanism 37 and the rotating unit 34. A primary pulley 52a and a secondary pulley 52b are arranged on the surface of the claw 24 facing outward in the opening and closing direction. The timing belt 50 is wound around the primary pulley 52a and the secondary pulley 52b. The secondary pulley 52b is arranged coaxially with the rotation axis X1 of the rotating unit 34 and is connected to the shaft 40 of the rotating unit 34.

[0050] The primary pulley 52a is connected to the telescopic rotation mechanism 37. The telescopic rotation mechanism 37 is disposed between the second drive source 36 and the power transmission mechanism 35 and is capable of extending and retracting in the gripping direction D1 and the releasing direction D2. In other words, the telescopic rotation mechanism 37 transmits the rotation of the second drive source 36 to the power transmission mechanism 35 and moves in the gripping direction D1 and the releasing direction D2 relative to the second drive source 36.

[0051] In detail, the telescopic rotation mechanism 37 has a first rotating shaft 44 connected to the output shaft 36a of the second drive source 36, a second rotating shaft 46 connected to the primary pulley 52a of the power transmission mechanism 35, and a telescopic rotation structure 48 provided between the first rotating shaft 44 and the second rotating shaft 46. That is, in this embodiment, the primary pulley 52a of the power transmission mechanism 35 constitutes the inlet rotating body of the power transmission mechanism 35 to which the second rotating shaft 46 is connected.

[0052] As shown in FIG. 4B , the telescopic rotation structure 48 transmits the rotation of the first rotation shaft 44 to the second rotation shaft 46 and supports the second rotation shaft 46 movably relative to the first rotation shaft 44 in a gripping direction D1 and a releasing direction D2.

[0053] 4A , the telescopic rotation structure 48 includes a cylindrical outer member 54, an inner member 56 inserted into a hollow hole 54c of the outer member 54, and rolling elements 58 interposed between the outer member 54 and the inner member 56. In this embodiment, the rolling elements 58 are eight balls arranged in the circumferential direction. However, the shape and number of the rolling elements 58 are not limited to this.

[0054] In this embodiment, the outer member 54 is cylindrical with one end (the left end in FIG. 4C ) closed and the other end open, and the shaft end of the first rotating shaft 44 is connected to the bottom 54a of the one end. In this embodiment, the first rotating shaft 44 and the outer member 54 are inseparably formed as a single unit. In other words, the outer member 54 is provided on the shaft end of the first rotating shaft 44. That is, one end of the first rotating shaft 44 is connected to the rotating shaft 36a of the second driving source 36, and the other end is connected to the outer member 54. Therefore, the outer member 54 is rotatable around the axis X2 of the rotating shaft 36a of the second driving source 36 relative to the gripper 22 ( FIG. 2A ).

[0055] 4C , grooves 54b extending in the axial direction are formed on the inner circumferential surface of the outer member 54. A plurality of grooves 54b are provided and aligned in the circumferential direction. In this embodiment, the number of grooves 54b is the same as the number of rolling elements 58, i.e., eight.

[0056] As shown in Fig. 4A, in this embodiment, the inner member 56 has a cylindrical shape, and one end surface (the right end surface in Fig. 4C) is connected to the shaft end portion of the second rotating shaft 46. In this embodiment, the second rotating shaft 46 and the inner member 56 are formed as an inseparable unit. In other words, the inner member 56 is provided on the shaft end portion of the second rotating shaft 46. A circumferential groove 56a extending in the circumferential direction is formed on the outer diameter surface of the axially intermediate portion of the inner member 56.

[0057] 4C , the outer diameter of the inner member 56 is set to be slightly smaller than the inner diameter of the outer member 54 and larger than the outer diameter of the second rotating shaft 46. Rolling elements 58 are disposed between the inner diameter surface of the outer member 54 and the outer diameter surface of the inner member 56. In other words, the rotation of the outer member 54 is transmitted to the inner member 56 via the rolling elements 58. In other words, the inner member 56 is rotatably connected to the outer member 54 via the rolling elements 58.

[0058] Specifically, the rolling elements 58 are disposed between the circumferential grooves 56a of the inner member 56 and the grooves 54b of the outer member 54. The rolling elements 58 are movable in the axial direction (opening / closing direction) along the grooves 54b of the outer member 54. In other words, the inner member 56 is rotatable around the axis X2 of the rotation shaft 36a of the second drive source 36 relative to the gripping portion 22 (FIG. 2A), and is movable in a direction parallel to the opening / closing direction.

[0059] The other end of the second rotating shaft 46 is connected to the power transmission member 35 of the rotation transmission mechanism 32. That is, one end of the second rotating shaft 46 is connected to the inner member 56, and is connected to an inlet rotating body (primary pulley) 52 a of the power transmission mechanism 35 of the rotation transmission mechanism 32.

[0060] The first and second rotary shafts 44, 46, the outer member 54, and the inner member 56 may be made of metal or resin. A lubricant such as grease may be filled in the gap between the outer member 54 and the inner member 56. In this case, a seal member may be provided at the open end of the outer member 54 to prevent the grease from leaking to the outside.

[0061] By providing such an extendable rotation mechanism 37, in Fig. 2A, the first rotation shaft 44 and the outer member 54 rotate about the axis X2 of the rotation shaft 36a of the second drive source 36, and the second rotation shaft 46 and the inner member 56 rotate via the rolling elements 58 (Fig. 4A). Furthermore, the second rotation shaft 46 and the inner member 56 move in a direction parallel to the opening and closing direction of the gripping mechanism 26 as the gripping mechanism 26 opens and closes. This allows rotational power to be transmitted to the rotating portion 34 at the tip of the claw portion 24 even when the gripping mechanism 26 opens and closes.

[0062] In this embodiment, an outer member 54 is provided at the axial end of the first rotating shaft 44, and an inner member 56 is provided at the axial end of the second rotating shaft 46, but it is also possible to provide an inner member 56 at the axial end of the first rotating shaft 44, and an outer member 54 at the axial end of the second rotating shaft 46.

[0063] In this embodiment, the rotation transmission mechanism 32 and the claw portion 24 are integrated to form a sub-assembly. Specifically, the rotating portion 34, the claw portion 24, the power transmission mechanism 35, the telescopic rotation mechanism 37, and the second drive source 36 are integrated. This integrated sub-assembly is attached to the gripping portion 22. This allows the claw portion 24 having the rotation transmission mechanism 32 of this embodiment to be applied to existing gripping portions. In particular, it is highly versatile because it can easily be adapted to the size of the gripping mechanism 26 and the length of the claw portion 24.

[0064] In other words, in this embodiment, the rotation transmission mechanism 32 and the claw portion 24 form an integrated module. Specifically, the rotating portion 34, the claw portion 24, the timing belt 50, the pulleys 52 a, 52 b, the first and second rotating shafts 44, 46, the outer member 54, the inner member 56, the rolling elements 58, and the second driving source 36 are modularized.

[0065] When the gripping device 6 grips the workpiece W, the first drive source 28 is driven to move the gripping mechanism 26 and the claws 24 fixed thereto in the gripping direction D1. At this time, the second drive source 36 fixed to the gripping body 30 and the first rotation shaft 44 and outer member 54 of the telescopic rotation mechanism 37 connected to the second drive source 36 do not move in the gripping direction D1.

[0066] Meanwhile, in the telescopic rotation mechanism 37, the inner member 56, which is connected to the outer member 54 via the rolling elements 58 so as to be movable in the opening and closing direction, and the second rotating shaft 46 move in the gripping direction D1. Furthermore, the rotation transmission mechanism 32 connected to the second rotating shaft 46 and the rotating part 34 connected to the rotation transmission mechanism 32 also move in the gripping direction D1.

[0067] When the second drive source 36 is driven while the gripping device 6 grips the workpiece W, the first rotating shaft 44 and the outer member 54 shown in Fig. 4C rotate. When the outer member 54 rotates, the inner member 56 and the second rotating shaft 46 rotate via the rolling elements 58.

[0068] When the second rotating shaft 46 rotates, the upstream pulley 52a in Fig. 2A rotates, and this rotation is transmitted to the downstream pulley 52b via the timing belt 50, causing the downstream pulley 52b to rotate. When the downstream pulley 52b rotates, one of the rotating parts 34 connected thereto rotates, and this rotation is transmitted to the other rotating part 34 via the workpiece W, causing the other rotating part 34 to also rotate. In other words, the workpiece W rotates around the rotation axis X1. This allows the posture of the workpiece W to be changed.

[0069] When the gripping device 6 releases the workpiece W, the first drive source 28 is driven to move the gripping mechanism 26 and the claw portion 24 fixed thereto in the release direction D2. At this time, similar to when gripping the workpiece W, the second drive source 36, the first rotation shaft 44 of the telescopic rotation mechanism 37, and the outer member 54 do not move in the release direction D2, but the inner member 56 of the telescopic rotation mechanism 37, the second rotation shaft 46, and the rotating portion 34 move in the release direction D2.

[0070] Generally, a gripping device 6 having two jaws 24 needs to change the size of the gripping portion 22 itself, the opening / closing stroke, the length of the jaws 24, etc. depending on the size of the workpiece W to be gripped. Fig. 20 shows a conventional picking system SY1. The gripping device 100 of this picking system SY1 has a structure in which the rotation transmission mechanism 32 is omitted from the gripping device (hand) 6 of this embodiment.

[0071] In the conventional gripping device 100, in order to change the posture of the gripped workpiece W, it is necessary to operate each of the arms 10A, 10B, and 10C of the robot 4. In particular, when turning the workpiece W over, it is necessary to prepare a temporary table 102, place the workpiece W on the temporary table 102, and then change the gripping position. Figure 21 shows the process of turning the workpiece W over.

[0072] In the first step of FIG. 21(a), the workpieces W are conveyed in random orientations on the first conveyor 2. The orientation and front and back of the workpieces W are determined using a camera or the like, and the workpieces W are gripped by the gripping device 100 installed on the robot 4 (FIG. 20). Next, in the second step of FIG. 21(b), the gripped workpieces W are temporarily placed on the temporary table 102. Next, in the third step of FIG. 21(c), the orientation of the gripping device 100 is changed, and the gripping device 100 re-grips the workpiece W from the opposite direction. Finally, in the fourth step of FIG. 21(d), the re-gripped workpieces W are placed on the second conveyor 3 with their orientation aligned.

[0073] Here, if the workpiece W on the first conveyor 2 is approached horizontally instead of from above, it may not be necessary to re-grasp the workpiece W as in the second and third processes. However, in this case, a large space is required between the robot 4 and the first conveyor 2. Also, depending on the orientation of the workpiece W, it may not be possible to grasp it if approached from the horizontal direction.

[0074] [Operation and Effect] According to the configuration of the present embodiment described above, as shown in FIG. 2A , the rotating unit 34 of the rotation transmission mechanism 32 is separately provided at the tip of the claw 24 attached to the gripping mechanism 26 of the gripping unit 22. The rotating unit 34 rotates the workpiece W around the rotation axis X1 parallel to the gripping direction D1 and the release direction D2 of the claw 24. The gripping mechanism 26 moves using the power of the first drive source 28, and the rotating unit 34 rotates using the power of the second drive source 36. In other words, the gripping mechanism 26 and the rotating unit 34 are provided independently. As a result, even if the height of the workpiece W to be gripped changes during a setup change, it is sufficient to replace the claw 24 and the rotation transmission mechanism 32 supported thereon, and there is no need to change the gripping unit 22. As a result, the length from the base of the claw 24 to the rotation axis of the second drive source 36 can be easily changed.

[0075] Furthermore, the second drive source 36 does not move in the opening / closing direction together with the gripping mechanism 26 of the gripping unit 22. This reduces the load in the opening / closing direction, allowing the gripping mechanism 26 to operate at high speed. Furthermore, since only the rotating unit 34 is rotated, rather than the entire gripping unit 22, the only objects that rotate are the workpiece W and the rotating unit 34, reducing the weight and moment of inertia of the rotating objects. As a result, high-speed rotation of the rotating unit 34 and low torque of the second drive source 36 are possible, allowing the second drive source 36 to be made smaller and lighter.

[0076] According to the above configuration, after gripping the workpiece W shown in Fig. 1, the workpiece W can be turned over by rotating it with the rotating unit 34 without having to be gripped again. This makes it possible to omit the second step (b) and the third step (c) shown in Fig. 21, thereby shortening the transport time. In addition, the temporary placement table 102 for changing the orientation of the workpiece W is no longer necessary, thereby realizing space savings.

[0077] Furthermore, in the case of the conventional structure shown in FIG. 20 , when re-gripping the workpiece W to flip it over, each arm 10A, 10B, 10C of the articulated robot 4 must move significantly. This requires time for the robot 4 to operate, and interference with surrounding objects must be considered. According to this embodiment, the workpiece W can be flipped over without re-gripping, thereby resolving these issues. Furthermore, because the workpiece W is rotated by the rotating unit 34 installed at the tip of the claw 24 shown in FIG. 2A , the moment of inertia is smaller than when the entire claw 24, including the gripping mechanism 26, is rotated. Therefore, the workpiece W can be rotated at a higher speed.

[0078] In this embodiment, the rotation transmission mechanism 32 and the claw 24 are integrated to form a sub-assembly, and this sub-assembly is attached to the gripping unit 22. Specifically, the rotating unit 34, the claw 24, the power transmission mechanism 35, the telescopic rotation mechanism 37, and the second drive source 36 are integrated. With this configuration, the claw 24 having the rotation transmission mechanism 32 can be applied to existing gripping units. In particular, it is highly versatile because it can easily be adapted to the size of the gripping mechanism 26 and the length of the claw 24.

[0079] In this embodiment, the telescopic rotation mechanism 37 has a first rotating shaft 44 connected to the output shaft 36a of the second drive source 36, a second rotating shaft 46 connected to the inlet rotating body 52a of the power transmission mechanism 35, and an telescopic rotation structure 48 that transmits the rotation of the first rotating shaft 44 to the second rotating shaft 46.

[0080] The telescopic rotation structure 48 supports the second rotation shaft 46 so that it can move in the opening and closing direction relative to the first rotation shaft 44. Specifically, the telescopic rotation structure 48 has a cylindrical outer member 54 provided at the shaft end of the first rotation shaft, an inner member 56 provided at the shaft end of the second rotation shaft 46 and inserted into a hollow hole in the outer member 54, and rolling elements 58 interposed between the outer member 54 and the inner member 56.

[0081] The rolling elements 58 transmit the rotation of the outer member 54 to the inner member 56, and support the inner member 56 so that it can move in the opening and closing direction relative to the outer member 54. With this configuration, rotational torque can be reliably transmitted in the rotational direction, and smooth movement with little resistance in the extension and retraction direction is possible.

[0082] In this embodiment, the second drive source 36 is an electric motor. By configuring the second drive source 36 as an electric motor, the posture of the workpiece W can be easily changed to any inclination. Not only can the workpiece W be turned over, but the inclination of the workpiece W can also be freely changed. This makes it possible to accommodate cases where it is better for the angle of the claw portion 24 to be inclined at a predetermined angle relative to the workpiece W, such as when the workpiece W is transported at an angle rather than flat, or when the workpiece W has a notch for gripping. Furthermore, it is easy to accommodate cases where the workpiece W must be placed at a predetermined angle after being gripped.

[0083] In this embodiment, the power transmission mechanism 35 has a timing belt 50. With this configuration, the length from the second drive source 36 to the rotating unit 34 can be easily changed, which increases the degree of freedom in arranging the second drive source 36.

[0084] Fig. 5 shows a modified example of the telescopic rotation structure 48A of the telescopic rotation mechanism 37A. The telescopic rotation structure 48A of the telescopic rotation mechanism 37A shown in Fig. 5 has a first gear 60 provided on the first rotation shaft 44 and having a long axial dimension, and a second gear 62 provided on the second rotation shaft 46 and having a shorter axial dimension than the first rotation shaft 44.

[0085] The axial dimension of the first gear 60 is set longer than the opening / closing width of the gripping mechanism 26 (FIG. 2A), i.e., the amount of movement in the opening / closing direction. The first rotating shaft 44 and the first gear 60 are rotatable around the rotation axis of the second driving source 36 relative to the gripping unit main body 30 (FIG. 2A). Furthermore, the first rotating shaft 44 and the first gear 60 do not move in the opening / closing direction.

[0086] When the second gear 62 meshes with the first gear 60, the rotation of the first gear 60 is transmitted to the second gear 62 and the second rotating shaft 46, and the second gear 62 and the second rotating shaft 46 can move in the opening / closing direction (axial direction).

[0087] With this configuration, rotation of the second drive source 36 causes the first rotating shaft 44 and the first gear 60 to rotate about the rotation axis, and meshing of the gears 60, 62 causes the second gear 62 and the second rotating shaft 46 to rotate. Furthermore, as the gripping mechanism 26 of FIG. 2A opens and closes, meshing of the first and second gears 60, 62 causes the second gear 62 and the second rotating shaft 46 to move in a direction parallel to the opening and closing direction. Therefore, even when the gripping mechanism 26 opens and closes, rotational power can be transmitted to the rotating portion 34 at the tip of the claw portion 24. Thus, with a small number of parts, the modified example of FIG. 5 can reliably transmit rotational torque in the rotational direction and is movable in the extension and retraction direction.

[0088] In Figure 5, a first gear 60 with a long axial dimension is provided on the first rotating shaft 44, and a second gear 62 is provided on the second rotating shaft 46, but it is also possible to provide a first gear 60 with a long axial dimension on the second rotating shaft 46, and a second gear 62 on the first rotating shaft 44.

[0089] 6 shows a gripping device (hand) 6A according to a first modification of this embodiment. In this first modification, the power transmission mechanism 35 has a rod 65 with bevel gears 64 attached to both ends. The bevel gears 64 may be straight or helical gears.

[0090] The rod 65 extends between the rotation axis X2 of the second drive source 36 and the rotation axis X1 of the rotating unit 34 in a direction perpendicular to both axes X1 and X2. The bevel gear 64 has a primary bevel gear 64a on the second drive source 36 side and a secondary bevel gear 64b on the rotating unit 34 side.

[0091] A drive-side bevel gear 66 is provided at the tip of the second rotation shaft 46 of the telescopic rotation mechanism 37, and the drive-side bevel gear 66 meshes with the primary bevel gear 64a. The drive-side bevel gear 66 is disposed coaxially with the rotation axis X2 of the second drive source 36, and the rotation of the second drive source 36 is transmitted to the drive-side bevel gear 66 via the telescopic rotation mechanism 37. In other words, in the first modified example, the primary bevel gear 64a constitutes an inlet rotor of the power transmission mechanism 35 to which the second rotation shaft 46 of the telescopic rotation mechanism 37 is connected.

[0092] A driven bevel gear 68 is provided at the tip of the shaft 40 of the rotating unit 34, and the driven bevel gear 68 meshes with the secondary bevel gear 64b. The driven bevel gear 68 is disposed coaxially with the rotation axis X1 of the rotating unit 34, and the rotation of the second drive source 36 is transmitted to the driven bevel gear 68 via the rotation transmission mechanism 32. In this way, the power of the second drive source 36 is transmitted to the rotating unit 34.

[0093] In the first variant, by using a rod 65 with bevel gears 64 at both ends as the power transmission mechanism 35, the length from the second drive source 36 to the rotating part 34 can be easily changed, thereby increasing the degree of freedom in the placement of the second drive source 36.

[0094] 7 shows a gripping device (hand) 6B according to a second modification of this embodiment. In the second modification, the power transmission mechanism 35 has a plurality of spur gears 69. In the second modification, the spur gears 69 have a primary spur gear 69a on the second drive source 36 side and a secondary spur gear 69b on the rotating unit 34 side. However, there may be three or more spur gears 69. In the second modification, the primary spur gear 69a has a larger diameter than the secondary spur gear 69b, but they may have the same diameter, or the secondary spur gear 69b may have a larger diameter than the primary spur gear 69a.

[0095] The primary spur gear 69a is provided at the tip of the second rotation shaft 46 of the telescopic rotation mechanism 37. The primary spur gear 69a is disposed coaxially with the rotation shaft X2 of the second drive source 36, and the rotation of the second drive source 36 is transmitted to the primary spur gear 69a via the telescopic rotation mechanism 37. In other words, in the first modified example, the primary spur gear 69a constitutes an inlet rotor of the power transmission mechanism 35 to which the second rotation shaft 46 of the telescopic rotation mechanism 37 is connected.

[0096] The primary spur gear 69a and the secondary spur gear 69b mesh together, and when the primary spur gear 69a rotates, the secondary spur gear 69b also rotates. The secondary spur gear 69b is provided at the tip of the shaft 40 of the rotating unit 34. The secondary spur gear 69b is arranged coaxially with the rotation axis X1 of the rotating unit 34, and the rotation of the second driving source 36 is transmitted to the secondary spur gear 69b via the rotation transmission mechanism 32. In this way, the power of the second driving source 36 is transmitted to the rotating unit 34.

[0097] According to the second variant, the rotation speed of the rotating part 34 and the distance to the rotating part 34 can be adjusted by changing the diameter and number of the spur gear 69, thereby increasing the degree of freedom in the capacity, arrangement, etc. of the second drive source 36.

[0098] 8A and 8B show a gripping device (hand) 6C according to a third modification of this embodiment. The gripping device 6C according to the third modification is mounted on the picking system SY shown in FIG. 2A and 2B. In the example shown in FIGS. 2A and 2B, the output shaft 36a of the second drive source 36 is directly connected to the first rotation shaft 44 of the telescopic rotation mechanism 37, and the telescopic rotation mechanism 37 is disposed coaxially with the rotation axis X2 of the second drive source 36. However, in the third modification, the output shaft 36a of the second drive source 36 is connected to the first rotation shaft 44 of the telescopic rotation mechanism 37 via a belt 70 and a pair of pulleys 72, 72. In other words, the rotation axis X2 of the second drive source 36 does not coincide with the rotation axis X3 of the telescopic rotation mechanism 37.

[0099] In detail, one pulley 72 is provided on the output shaft 36a of the second drive source 36, and the other pulley 72 is provided on the first rotation shaft 44 of the telescopic rotation mechanism 37, with a belt 70 stretched around both pulleys 72, 72. In this way, the rotation of the second drive source 36 is transmitted to the telescopic rotation mechanism 37. The other structure is the same as the example in Figures 2A and 2B.

[0100] 2A and 2B , the third modification allows the size of the gripper body 30 of the gripper 22 in the opening / closing direction to be smaller than in the configuration in which the telescopic rotation mechanism 37 and the second drive source 36 are coaxially installed. This makes it possible to prevent the gripping device 6C from interfering with surrounding objects. In the third modification, the second drive source 36 and the telescopic rotation mechanism 37 are connected by a combination of a pulley 72 and a belt 70, but a combination of a sprocket and a chain, or a combination of multiple gears, may also be used.

[0101] FIG. 9 shows a gripping device (hand) 6D according to a fourth modified example of this embodiment. The gripping device 6D of the fourth modified example differs from the example of FIG. 2A in that the gripping surface 74 of the rotating part 34A is inclined. A gripping device 6D having such an inclined gripping surface 74 is advantageous for gripping a cylindrical workpiece W such as a bolt. The other configurations of the fourth modified example of FIG. 9 are the same as those of the example of FIG. 2A. The differences from the example of FIG. 2A will be described in detail below.

[0102] 10 is an enlarged view of the claw portion 24 of the gripping device 6D of the fourth modified example. In the following description, the direction in which the claw portion 24 extends is referred to as the "longitudinal direction DR1," and the direction in which the claw portion 24 opens and closes is referred to as the "opening / closing direction DR2." In addition, the direction perpendicular to both the longitudinal direction DR1 and the opening / closing direction DR2 is referred to as the "orthogonal direction DR3."

[0103] The gripping surface 74 has a first inclined surface 75 that extends from an end 74a on the proximal side in the longitudinal direction DR1 (upper side in FIG. 10) toward the distal side in the longitudinal direction DR1 (lower side in FIG. 10) at an incline in the opening direction, and a second inclined surface 76 that extends from an end 74b on the distal side in the longitudinal direction DR1 (lower side in FIG. 10) toward the proximal side in the longitudinal direction DR1 at an incline in the opening direction. The distal end of the first inclined surface 75 and the proximal end of the second inclined surface 76 are connected by a connecting portion 77.

[0104] 10, when viewed from the orthogonal direction DR3, the edge of the inclined surface 74 (the edge in the orthogonal direction) is V-shaped and recessed in the opening direction. The four surfaces 75, 75, 76, 76 of the pair of rotating parts 34A, 34A form a tangential plane that comes into contact with the cylindrical workpiece W to be gripped. In the following description, the base end 74a may be referred to as the "base end corner 74a," and the tip end 74b may be referred to as the "tip end corner 74b."

[0105] When viewed from the orthogonal direction DR3, the angle between a leading-end imaginary line V1 extending from the second inclined surface 76 toward the leading end (lower side in FIG. 10 ) and the horizontal conveying surface 2a of the conveyor 2 is defined as a leading-end angle α. When viewed from the orthogonal direction DR3, the angle between a proximal imaginary line V2 extending from the first inclined surface 75 toward the proximal end (upper side in FIG. 10 ) and a parallel line LN parallel to the conveying surface 2a is defined as a proximal end angle β. Furthermore, the angle between the first inclined surface 75 and the second inclined surface 76 is defined as an inclination angle γ. In this example, the leading-end angle α is set smaller than the proximal end angle β. That is, α<β.

[0106] Furthermore, in this embodiment, the distal angle α is set to be equal to or greater than 25° and equal to or less than 30° (25°≦α≦30°), while the proximal angle β is set to be greater than 50° and smaller than 60° (50°<β<60°).

[0107] The base end 74a and tip end 74b of the rotating part 34A, i.e., the base end and tip end corners 74a, 74b of the rotating part 34A, are rounded. In other words, the base end and tip end corners 74a, 74b of the rotating part 34A have an R-shape. This prevents the corners 74a, 74b of the rotating part 34A from scratching the workpiece W. In this example, both the base end corner 74a and tip end corner 74b are R-shaped, but only the tip end corner 74b may be R-shaped.

[0108] Furthermore, the surface 78 (the bottom surface 78 of the rotating part 34A in FIG. 10 ) that forms the tip corner 74b and does not come into contact with the workpiece W is configured to be parallel to the horizontal conveying surface 2a of the conveyor 2 when the longitudinal direction DR1 of the claw part 24 is perpendicular to the horizontal conveying surface 2a of the conveyor 2. Alternatively, the bottom surface 58 of the rotating part 34A may be inclined so that the tip corner 52b is at the lower end relative to the conveying surface 22a. This makes it possible to prevent interference between the bottom surface 58 of the rotating part 34A and the conveyor 2.

[0109] As shown by the two-dot chain lines in FIG. 10 , sliding members 79 may be attached to the first inclined surface 75 and the second inclined surface 76 of the rotating portion 34A. The sliding members 79 are preferably made of a material that has high slidability and is lower in hardness than the workpiece W. To achieve high slidability, the sliding members 79 have a surface friction coefficient of 0.2 or less. Examples of materials for the sliding members 79 include polyoxymethylene (POM) and monomer cast nylon (MC nylon). However, the material of the sliding members 79 is not limited to these. The provision of the sliding members 79 can prevent the workpiece W from being damaged. Furthermore, setting the friction coefficient to 0.2 or less facilitates movement of the workpiece W along the inclined surfaces 75 and 76. Therefore, a cylindrical workpiece W slightly tilted relative to the conveyor 2 can be held in a stable position where the four surfaces 75 and 76 are tangent to each other.

[0110] The sliding member 79 may be attached to only one of the first and second inclined surfaces 75, 76. In this case, the sliding member 79 may be attached only to the second inclined surface 76 on the tip side which is more likely to damage the workpiece W. The sliding member 79 may also be detachably attached to the inclined surfaces 75, 76. As an example, an engagement groove may be provided in the inclined surfaces 75, 76, and the sliding member 79 may be detachably attached to this engagement groove. However, the method of attaching the sliding member 79 is not limited to this. Making only the sliding member 79 replaceable is less expensive than replacing the entire claw portion 24, and maintenance costs can be reduced.

[0111] As described above, in order to obtain high slidability, it is preferable that the coefficient of friction of the surface of the sliding member 79 is set to 0.2 or less, but, for example, the coefficient of friction of the surface of the sliding member 79 may be set to be smaller than the coefficient of friction of the surfaces of the rotating part 34A other than the inclined surfaces 75 and 76. Furthermore, instead of attaching the sliding member 79, the coefficient of friction may be reduced by applying a surface treatment such as coating or polishing to the inclined surfaces 75 and 76.

[0112] In a picking system, for example, due to a change in the model number of a product produced on a production line, workpieces W of a different shape than those input before the change may be input, or workpieces W of different shapes may be input simultaneously onto the conveyor 2. Workpieces W of different shapes are often similar in shape, and for example, bolts or pins with the same screw diameter but different lengths may be input due to a change in setup or input simultaneously.

[0113] Because the outer diameter of the head of the bolt is larger than the outer diameter of the shank, the bolt is placed at a slight angle relative to the horizontal conveying surface 2a. However, if compressed air or the like is used as the first driving source 28, the operating angle cannot be adjusted automatically, and manual adjustment takes time. If an electric motor is used as the first driving source 28, the angle operation can be adjusted, but this increases costs and complicates control. Therefore, it is desirable to be able to pick up both workpieces W that are inclined and horizontal with respect to the conveying surface 2a without changing the operating angle of the first driving source 28.

[0114] In the hand 6D of the fourth modification, when picking up a bolt-shaped workpiece W that is tilted relative to the conveying surface 2a from above in the radial direction, the workpiece W is picked up by scooping it up with the corner 74b on the tip side of the rotating part 34A. At this time, because the tip side angle α is small, even a workpiece W tilted relative to the conveying surface 2a can be easily picked up.

[0115] Furthermore, since the base end angle β is set to an appropriate value, the cylindrical workpiece W can easily follow the four inclined surfaces 75, 76. As a result, the cylindrical workpiece W can be picked up in a horizontally stable position.

[0116] 1 shows an example in which the gripping device 6 of this embodiment is applied to a picking system SY that includes a process of turning over the workpieces W, but other application examples will be described with reference to Fig. 11. Fig. 11 shows a process in which a workpiece Wa to be gripped is gripped and removed from the workpieces W that are randomly stacked in a container 82 using an articulated robot 4A.

[0117] 22 shows a process for gripping and removing a workpiece Wa to be gripped from workpieces W randomly piled in a container 82 using a conventional gripping device 100 that does not have a rotation transmission mechanism 32. In such a process, the orientation of the claws 24 may be restricted relative to the workpiece Wa to be gripped. In this case, depending on the position and orientation of the workpiece Wa to be gripped, as shown in FIG. 23, there is a risk that the claws 24, gripper 22, robot 4, etc. may interfere with the container 82 or its surrounding objects when approaching the workpiece Wa to be gripped.

[0118] 11, in the example in which the gripping device 6 of the embodiment is applied, the workpiece W can be rotated at the tip of the claw portion 24, which increases the degree of freedom in the angle at which the gripping target workpiece Wa is approached. This makes it possible to avoid the claw portion 24, gripping portion 22, robot 4, etc. from interfering with the container 82 or its surrounding objects. In addition, it is possible to grip a workpiece W that is located in the corner of the container 82 and cannot be gripped by a conventional robot.

[0119] Second Embodiment Fig. 12 shows a gripping device (hand) 6E according to a second embodiment of the present invention. The hand 6E of the second embodiment has three claws 24, each of which has a rotating unit 34 at its tip. In Fig. 12, the three claws 24 are spaced circumferentially at 120° intervals, i.e., at equal intervals, but they do not have to be spaced at equal intervals. In the second embodiment, the rotating unit main body 38A of the rotating unit 34 is not disk-shaped as in the first embodiment, but is a smooth sphere that sandwiches the workpiece W from three sides.

[0120] 12 , the power of the second drive source 36 is transmitted to one of the three claws 24, but not to the other two claws 24. However, the second drive source 36 may be installed so that power is transmitted to all of the claws 24, or the second drive source 36 may be installed so that power is transmitted to two of the three claws 24.

[0121] 12 , the rotation axis X1 of the rotating unit 34 and the rotation axis X3 of the telescopic rotation mechanism 37 are parallel to each other, but the rotation axis X1 of the second driving source 36 and the rotation axis X1 of the rotating unit 34 are not parallel to each other. In this embodiment, the output shaft 36 a of the second driving source 36 and the first rotation shaft 44 of the telescopic rotation mechanism 37 are connected via a bevel gear 80.

[0122] More specifically, a bevel gear 80a on the drive source side is provided on the rotation shaft 36a of the second drive source 36, and a bevel gear 80b on the mechanism side is provided on the first rotation shaft 44 of the telescopic rotation mechanism 37, with the gears 80a and 80b meshing with each other. As a result, the power of the second drive source 36 is transmitted to the telescopic rotation mechanism 37 via the bevel gear 80. The other configurations are the same as those of the first embodiment shown in Figures 2A and 2B.

[0123] In the second embodiment, as in the first embodiment, even if the height of the workpiece W to be grasped during setup change is different, the length from the base of the claw portion 24 to the rotation axis X1 can be easily changed.

[0124] 13A to 14, the configuration of a hand 6F according to a third embodiment of the present invention will be described. In the following description, the same components as those in the previous embodiment will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0125] The hand 6F of the third embodiment differs from the first embodiment in that a rotation transmission mechanism 32A is attached to the claw portion 24 and moves together with the claw portion 24 in the gripping direction D1 and the releasing direction D2.

[0126] 13A and 13B, the rotation transmission mechanism 32A of the hand 6F of the third embodiment has a rotating unit 34 that is rotatable about the rotation axis X1 relative to the claws 24, and a second drive source 36A that rotationally drives the rotating unit 34 about the rotation axis X1. However, the rotation transmission mechanism 32A of the third embodiment does not have the power transmission mechanism 35 and the telescopic rotation mechanism 37 of the first embodiment shown in FIGS. 2A and 2B.

[0127] 13A , in the third embodiment, the rotating unit 34 is attached to each of the plurality of claws 24 and moves in the opening and closing direction together with the claw 24. The second driving source 36A is attached to at least one of the claws 24 and moves in the opening and closing direction together with the claw 24. In this way, the rotation transmission mechanism 32A moves in the opening and closing direction together with the claw 24. In the third embodiment, the second driving source 36A is attached to only one of the two claws 24, but it may be attached to both.

[0128] As shown in Figure 14, a second drive source 36A is connected to the tip of the shaft 40 of one of the rotating units 34. In this embodiment, the rotation axis RA of the second drive source 36A and the rotation axis X1 of the rotating unit 34 are aligned. A retaining member 45 is attached to the tip of the shaft 40 of the other rotating unit 34 to which the second drive source 36A is not connected. The retaining member 45 is, for example, a nut. The other configurations are the same as those of the first embodiment.

[0129] When the second drive source 36A is driven while the hand 6 is gripping the workpiece W, one of the rotating parts 34 rotates, and this rotation is transmitted to the other rotating part 34 via the workpiece W, causing the other rotating part 34 to also rotate. In other words, the workpiece W rotates around the rotation axis X1.

[0130] [Operation and Effect] According to the configuration of the third embodiment described above, as shown in Fig. 13A, the rotation unit 34 and second drive source 36A for rotating the workpiece W are separate from the first drive source 28 of the gripping mechanism 26, which allows for easy replacement during setup changeover. As a result, even if the height of the workpiece W to be gripped is different, this can be easily accommodated by replacing the rotation transmission mechanism 32 along with the claws 24. Furthermore, in the third embodiment, the power transmission mechanism 35 and the telescopic rotation mechanism 37 are omitted, which reduces the number of parts and simplifies the configuration.

[0131] 15A and 15B show a gripping device (hand) 6G according to a first modified example of the third embodiment. In the first modified example, the second drive source 36B that rotates the rotating unit 34 is configured as an electric motor. In this example, the electric motor 36B is directly connected to the rotating unit 34. Specifically, the rotation axis RA of the electric motor 36B coincides with the rotation axis X1 of the rotating unit 34. In the illustrated example, the electric motor 36B is installed on one of the two claws 24, 24, and the other rotating unit 34 is configured to be driven by it, but the electric motor 36B may be installed on both of the two claws 24, 24.

[0132] By configuring the second drive source 36B as an electric motor, the posture of the workpiece W can be easily changed to any inclination. Not only can the workpiece W be turned over, but the inclination of the workpiece W can also be freely changed, which makes it possible to accommodate cases where it is better for the angle of the claw portion 24 to be inclined at a predetermined angle relative to the workpiece W, such as when the workpiece W is transported at an angle rather than flat, or when there is a notch for gripping. Furthermore, it is easy to accommodate cases where the workpiece W must be placed at a predetermined angle after being gripped.

[0133] Fig. 16 shows a gripping device (hand) 6H according to a second modified example of the third embodiment. In the second modified example, the rotation transmission mechanism 32A has a power transmission mechanism 90 that transmits the power of the second drive source 36B to the rotating unit 34, and the rotation axis RA of the second drive source 36B is perpendicular to the rotation axis X1 of the rotating unit 34. In the example of Fig. 16, a bevel gear 90A is used as the power transmission mechanism 90. The bevel gear 90A may be a "straight gear" or a "helical gear." Furthermore, the power transmission mechanism 90 may be a gear other than a bevel gear.

[0134] 16, an electric motor is used as the second drive source 36B. However, the second drive source 36B is not limited to an electric motor. The second drive source 36B is attached to a surface of the claw portion 24 facing outward in the opening and closing direction via a motor holder 92.

[0135] A bevel gear 90A is provided between the second drive source 36B and the rotating unit 34. The bevel gear 90A has a primary gear 90Aa and a secondary gear 90Ab, and the two gears 90Aa, 90Ab mesh with each other. The primary gear 90Aa is arranged coaxially with the rotation axis RA of the second drive source 36B and is connected to the second drive source 36B. The secondary gear 90Ab is arranged coaxially with the rotation axis X1 of the rotating unit 34 and is connected to the rotating unit 34. As a result, the power of the second drive source 36B is transmitted to the rotating unit 34 via the bevel gear 90A.

[0136] In the second modified example, by using a bevel gear 90A as the power transmission mechanism 90, it is not necessary to install the electric motor 36B so that the rotation axis RA of the electric motor 36B is parallel to the rotation axis X1 of the rotating part 34. Therefore, it is possible to prevent the electric motor 36B from protruding from the claw part 24 in the opening / closing direction.

[0137] FIG. 17 shows a gripping device (hand) 6I according to a third modified example of the third embodiment. In the third modified example, similar to the second modified example, the rotation transmission mechanism 32A includes a power transmission mechanism 90 that transmits power from a second drive source 36B to the rotating unit 34, and the rotation axis RA of the second drive source 36B is offset parallel to the rotation axis X1 of the rotating unit 34. In the example shown in FIG. 17 , a belt-shaped endless power transmission member 90B, specifically a timing belt, is used as the power transmission mechanism 90. The endless power transmission member 90B may also be a drive chain.

[0138] 17, an electric motor is used as the second drive source 36B. However, the second drive source 36B is not limited to an electric motor. The second drive source 36B is attached to a surface of the claw 24 facing inward in the opening and closing direction via a motor holder 92. In other words, the second drive source 36B is disposed inside the claw 24 and does not protrude outward from the claw 24 in the opening and closing direction.

[0139] A timing belt 90B is provided between the second drive source 36B and the rotating unit 34. A primary pulley 94a and a secondary pulley 94b are arranged on the surface of the claw 24 facing inward in the opening and closing direction. The primary pulley 94a is arranged coaxially with the rotation axis RA of the second drive source 36B and is connected to the second drive source 36B. The secondary pulley 94b is arranged coaxially with the rotation axis X1 of the rotating unit 34 and is connected to the rotating unit 34. The timing belt 90B is stretched between the primary pulley 94a and the secondary pulley 94b. As a result, the power of the second drive source 36B is transmitted to the rotating unit 34 via the timing belt 90B.

[0140] In the third modified example, the degree of freedom in arranging the second drive source 36B is increased by using a timing belt 90B as the power transmission mechanism 90. This allows the second drive source 36B to be arranged so as not to protrude outward from the claw portion 24 in the opening / closing direction, as shown in FIG.

[0141] 18 shows a gripping device (hand) 6J according to a fourth modification of the third embodiment. In this fourth modification, each gripping mechanism 26B is formed of a parallel link mechanism. That is, the gripping body 30 including the first drive source 28 and the claws 24 are connected via the parallel link mechanism 26B, and the claws 24 are opened and closed by the power of the first drive source 28.

[0142] In the example of Fig. 18, an electric motor is used as the second drive source 36B. However, the second drive source 36B is not limited to an electric motor. Furthermore, the power of the second drive source 36B is transmitted to the rotating unit 34 via a bevel gear 90A. In other words, the rotation axis RA of the second drive source 36B is perpendicular to the rotation axis X1 of the rotating unit 34. However, the power of the second drive source 36B may be transmitted to the rotating unit 34 by a power transmission mechanism other than a bevel gear.

[0143] The second drive source 36B is attached via a motor holder 92 to a surface facing outward in the opening and closing direction of the claw portion 24. A bevel gear 90A is provided between the second drive source 36B and the rotating portion 34. The arrangement of the bevel gear 90A is the same as in the second modified example shown in Fig. 16, so a detailed description thereof will be omitted.

[0144] According to the fourth modification, the parallel link mechanism 26B is used as the gripping mechanism, so that the tip of the claw 24 moves not only in the opening and closing direction but also in a direction perpendicular to the opening and closing direction. Therefore, as in the above embodiment, by providing the rotating unit 34 and the second drive source 36B as separate structures from the gripping unit 22, a simple mechanism can be realized.

[0145] [Fourth embodiment] Fig. 19 shows a gripping device (hand) 6K according to a fourth embodiment of the present invention. The hand 6K of the fourth embodiment has three claws 24, and a rotating portion 34 is provided at the tip of each claw 24. In Fig. 19, the three claws 24 are arranged at 120° intervals in the circumferential direction, i.e., at equal intervals, but they do not have to be arranged at equal intervals.

[0146] In Fig. 19 , an electric motor is used as the second drive source 36B. However, the second drive source 36B is not limited to an electric motor. In the example of Fig. 19 , the second drive source 36B is installed in one of the three claws 24, but not in the other two claws 24. However, the second drive source 36B may be installed in all claws 24, or may be installed in two of the three claws 24.

[0147] Furthermore, the power of the second drive source 36B is transmitted to the rotating unit 34 via a bevel gear 90A. In other words, the rotation axis RA of the second drive source 36B is perpendicular to the rotation axis X1 of the rotating unit 34. However, the power of the second drive source 36B may be transmitted to the rotating unit 34 by a power transmission mechanism other than a bevel gear. In the fourth embodiment, the rotating unit main body 38A of the rotating unit 34 is not disk-shaped as in the third embodiment, but is a smooth sphere that sandwiches the workpiece W on three sides.

[0148] The second drive source 36B is attached via a motor holder 92 to a surface facing outward in the opening and closing direction of the claw portion 24. A bevel gear 90A is provided between the second drive source 36B and the rotating portion 34. The arrangement of the bevel gear 90A is the same as that in the second modified example of the third embodiment shown in Figure 16, so a detailed description will be omitted. The other configurations are the same as those of the third embodiment.

[0149] In the fourth embodiment, as in the third embodiment, even if the height of the workpiece W to be grasped during setup change is different, the length from the base of the claw portion 24 to the rotation axis X1 can be easily changed.

[0150] The present invention is not limited to the above-described embodiments, and various additions, modifications, and omissions are possible without departing from the spirit of the present invention. Therefore, such additions, modifications, and omissions are also included in the scope of the present invention.

[0151] 6, 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H, 6I, 6J, 6K: hand (gripping device), 22: gripping portion, 24: claw portion, 26, 26A, 26B: gripping mechanism, 28: first driving source, 32, 32A: rotation transmission mechanism, 34, 34A: rotating portion, 35: power transmission mechanism, 36: second driving source (motor), 36A: second driving source, 36B: motor (second driving source), 37, 37A: telescopic rotation mechanism, 44: first rotating shaft, 46: second rotating shaft, 48, 48A : Telescopic rotating structure, 50: Timing belt (endless power transmission member), 52a: Primary pulley (inlet rotor of power transmission mechanism), 54: Outer member, 56: Inner member, 58: Rolling element, 60: First gear, 62: Second gear, 64: Bevel gear, 64a: Primary bevel gear (inlet rotor of power transmission mechanism), 65: Rod, 69: Spur gear, 90, 90A, 90B: Power transmission mechanism, 90A: Bevel gear, 90B: Timing belt (endless power transmission member), W: Work

Claims

1. A device comprising: a plurality of claws for gripping or releasing a workpiece; a gripping unit for moving the claws in a gripping direction to grip the workpiece and a release direction to release the workpiece; and a rotation transmission mechanism for rotating the workpiece gripped by the claws around a rotation axis parallel to the gripping direction and the release direction, wherein the gripping unit has a gripping mechanism to which the claws are attached and which moves in the gripping direction and the release direction, and a first drive source for moving the gripping mechanism in the gripping direction and the release direction, and the rotation transmission mechanism comprises: a rotating unit attached to each of the plurality of claws and which moves together with the claws in the gripping direction and the release direction and is rotatable around the rotation axis relative to the claws; a second drive source for driving the rotating unit to rotate around the rotation axis; and a power transmission mechanism connected to at least one of the rotating units and which moves together with the rotating unit in the gripping direction and the release direction, and which transmits power of the second drive source to the rotating unit. a telescopic rotation mechanism that is telescopic in the gripping direction and the release direction and that transmits the rotation of the second drive source to the power transmission mechanism.

2. A gripping device as claimed in claim 1, wherein the rotation transmission mechanism and the claw portion are integrated to form a sub-assembly, and the sub-assembly is attached to the gripping portion.

3. A gripping device according to claim 1 or 2, wherein the telescopic rotation mechanism comprises: a first rotating shaft connected to the output shaft of the second drive source; a second rotating shaft connected to the inlet rotating body of the power transmission mechanism; and an telescopic rotation structure that transmits the rotation of the first rotating shaft to the second rotating shaft and supports the second rotating shaft so that it can move relative to the first rotating shaft in the gripping direction and release direction.

4. A gripping device as described in claim 3, wherein the extendable rotation structure comprises: a cylindrical outer member provided at one end of the first rotation shaft and the second rotation shaft; an inner member provided at the other end of the first rotation shaft and the second rotation shaft and inserted into a hollow hole in the outer member; and a rolling element interposed between the outer member and the inner member, which transmits the rotation of the outer member to the inner member and supports the member provided on the second rotation shaft so that it can move in the gripping direction and release direction relative to the member provided on the first rotation shaft.

5. A gripping device as described in claim 3, wherein the extendable rotation structure comprises: a first gear provided on one of the first and second rotation shafts, the first gear having an axial dimension longer than the opening / closing width of the gripping mechanism; and a second gear provided on the other of the first and second rotation shafts, meshing with the first gear to transmit the rotation of the first gear and movable in the gripping direction and release direction relative to the first gear.

6. A gripping device according to any one of claims 1 to 5, wherein the second drive source is a motor.

7. A gripping device according to any one of claims 1 to 6, wherein the power transmission mechanism has a belt-shaped endless power transmission member.

8. A gripping device according to any one of claims 1 to 6, wherein the power transmission mechanism has a rod with bevel gears at both ends.

9. A gripping device according to any one of claims 1 to 6, wherein the power transmission mechanism has a plurality of spur gears.

10. A gripping device comprising: a plurality of claws for gripping or releasing a workpiece; a gripping unit for moving the claws in a gripping direction to grip the workpiece and a release direction to release the workpiece; and a rotation transmission mechanism for rotating the workpiece gripped by the claws around a rotation axis parallel to the gripping direction and the release direction, wherein the gripping unit has a gripping mechanism to which the claws are attached and which moves in the gripping direction and the release direction, and a first drive source for moving the gripping mechanism in the gripping direction and the release direction, and the rotation transmission mechanism has: a rotating unit attached to each of the plurality of claws and moving together with the claw in the gripping direction and the release direction and rotatable around the rotation axis relative to the claws; and a second drive source attached to at least one of the claws and moving together with the claw in the gripping direction and the release direction, and driving the rotating unit to rotate around the rotation axis.

11. The gripping device according to claim 10, wherein the second drive source is a motor.

12. A gripping device according to claim 10 or 11, wherein the rotation transmission mechanism further has a power transmission mechanism that transmits the power of the second drive source to the rotating part, and the rotation axis of the second drive source is perpendicular to the rotation axis of the rotating part.

13. A gripping device according to claim 12, wherein the power transmission mechanism is a bevel gear.

14. A gripping device according to any one of claims 10 to 13, wherein the rotation transmission mechanism further has a power transmission mechanism that transmits the power of the second drive source to the rotating part, and the rotation axis of the second drive source is offset parallel to the rotation axis of the rotating part.

15. A gripping device according to claim 14, wherein the power transmission mechanism is a belt-shaped endless power transmission member.

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