Electric gripper

Abstract

An electric gripper (10A) comprises a motor (34), a pair of moveable members (40) for gripping a workpiece, a guide rod (38) that guides the pair of moveable members, and a power transmission mechanism (42) that transmits power from the motor to the pair of moveable members so as to cause the pair of moveable members to move toward and away from one another along the guide rod. Each of the pair of moveable members is provided with a slide bearing (78) that slides with respect to the guide rod.

Description

Electric Gripper

[0001] The present invention relates to an electric gripper.

[0002] Japanese Patent Application Laid-Open No. 2018-176306 discloses an electric gripper including a motor and a pair of movable members for gripping a workpiece.

[0003] A better electric gripper is needed.

[0004] The present invention aims to solve the above-mentioned problems.

[0005] One aspect of the present invention is an electric gripper comprising a motor, a pair of movable members for gripping a workpiece, a guide rod for guiding the pair of movable members, and a power transmission mechanism for transmitting the power of the motor to the pair of movable members to move the pair of movable members closer to and apart along the guide rod, wherein each of the pair of movable members is provided with a sliding bearing that slides relative to the guide rod.

[0006] According to the present invention, a better electric gripper can be obtained.

[0007] FIG. 1 is a perspective view of an electric gripper according to a first embodiment of the present invention. FIG. 2 is a front view of the electric gripper of FIG. 1. FIG. 3 is a bottom view of the electric gripper of FIG. 1. FIG. 4 is an exploded perspective view of the electric gripper of FIG. 1. FIG. 5 is an exploded perspective view of the electric gripper of FIG. 1. FIG. 6 is a perspective view of a gripper main body. FIG. 7 is an exploded perspective view of the gripper main body with a portion thereof omitted. FIG. 8 is a vertical cross-sectional view of the electric gripper of FIG. 1. FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8. FIG. 10 is a cross-sectional view taken along line X-X of FIG. 8. FIG. 11 is a cross-sectional view taken along line XI-XI of FIG. 8. FIG. 12 is a perspective view of an electric gripper according to a second embodiment of the present invention. FIG. 13 is a front view of the electric gripper of FIG. 12. FIG. 14 is a bottom view of the electric gripper of FIG. 12. FIG. 15 is an exploded perspective view of the electric gripper of FIG. 12. FIG. 16 is a perspective view of the gripper main body. FIG. 17 is a vertical cross-sectional view of the electric gripper of FIG. 12. FIG. 18 is a cross-sectional view taken along line XVIII-XVIII in FIG.

[0008] First Embodiment An electric gripper 10A according to a first embodiment of the present invention will be described below with reference to the drawings. As shown in Fig. 1, the electric gripper 10A is attached to the tip of a robot arm (not shown) for use, for example. In describing the electric gripper 10A, the X direction in Fig. 1 may be referred to as the width direction, the Y direction in Fig. 1 as the thickness direction, and the Z direction in Fig. 1 as the height direction. The width direction, thickness direction, and height direction are perpendicular to one another.

[0009] 2 and 3, a pair of attachments 300 for gripping a workpiece can be attached to and detached from the electric gripper 10A. The shape, size, etc. of the attachments 300 are appropriately selected depending on the material, shape, size, etc. of the workpiece. The electric gripper 10A moves the pair of attachments 300 toward and away from each other in the X direction.

[0010] As shown in Fig. 1, the electric gripper 10A is formed in a vertically elongated shape. As shown in Figs. 1 to 3, the length (maximum length) L1 of the electric gripper 10A in the height direction (Z direction) is longer than the length (maximum length) L2 of the electric gripper 10A in the thickness direction (Y direction). Therefore, the electric gripper 10A can be made shorter in the thickness direction.

[0011] As shown in Figures 4 and 5, the electric gripper 10A includes a casing 12 and a gripper body 14. The casing 12 houses the gripper body 14. The casing 12 includes a first cover member 16 that covers the gripper body 14 from the Z1 direction and a second cover member 18 that covers the gripper body 14 from the Z2 direction. The first cover member 16 and the second cover member 18 are connected by a fastening member 20. As shown in Figure 4, an adapter 24 and an external connector 26 are attached to a first wall surface 22 of the first cover member 16 that faces the Z1 direction. The adapter 24 is detachable from the tip of the robot arm. A cable (not shown) is detachable from the external connector 26.

[0012] 3 and 5, a pair of elongated holes 30 extending in the width direction (X direction) is formed in the second wall surface 28 of the second cover member 18 facing the Z2 direction. The pair of elongated holes 30 are arranged side by side in the thickness direction (Y direction). Parts of a pair of movable members 40 forming the gripper body 14 are inserted into the pair of elongated holes 30. A pair of attachments 300 are detachably attached to the pair of movable members 40, respectively.

[0013] 6 to 11, the gripper body 14 includes a support member 32, a motor 34, a controller 36, a pair of guide rods 38, a pair of movable members 40, and a power transmission mechanism 42. The power transmission mechanism 42 has a feed screw shaft 44 for moving the pair of movable members 40 toward and away from each other. As shown in FIGS. 4 and 8, the adapter 24, the motor 34, the feed screw shaft 44, and the pair of guide rods 38 are arranged in this order along the height direction.

[0014] The support member 32 is fixed to the casing 12 by a plurality of fastening members (not shown). The support member 32 has relatively high rigidity. The support member 32 is integrally molded from, for example, a metal material or a hard resin material. The constituent material of the support member 32 is not particularly limited.

[0015] 7 and 8 , the support member 32 has a base portion 46, a pair of first support portions 48, and a second support portion 50. The base portion 46 is a plate-shaped portion extending in the X direction. A through-hole 52 is formed in the center of the base portion 46. The pair of first support portions 48 protrude in the Z2 direction from both ends of the base portion 46 in the X direction. The pair of first support portions 48 support the pair of guide rods 38.

[0016] As shown in Figures 7 and 9, each first support portion 48 is formed with a pair of rod support holes 54 through which the pair of guide rods 38 are inserted. The pair of rod support holes 54 are arranged at a distance in the Y direction. As shown in Figure 7, the second support portion 50 protrudes from the base portion 46 in the Z1 direction and extends in an annular shape. The second support portion 50 supports the power transmission mechanism 42. The internal space of the second support portion 50 communicates with the through-hole 52.

[0017] As shown in Figures 4, 6, and 8, the motor 34 is driven by power supplied via the external connector 26. The motor 34 extends in the X direction. The motor 34 has a motor body 56 and a rotating shaft 58. The motor body 56 is formed in a rectangular parallelepiped shape. The motor body 56 is fixed to the support member 32 via a plate member 59. The rotating shaft 58 protrudes from the motor body 56 in the X1 direction.

[0018] The controller 36 controls the motor 34. The controller 36 is integrally provided on a surface of the motor body 56 facing away from the rotation shaft 58 (in the X2 direction). As shown in FIG. 6 , the length of the controller 36 in the Y direction is longer than the length of the motor body 56 in the Y direction. The controller 36 is formed in an L-shape when viewed from the Z direction. The controller 36 has a protrusion 60 that protrudes in the Y2 direction beyond the motor body 56.

[0019] The protrusion 60 extends in the X1 direction. A portion of the protrusion 60 overlaps with the motor main body 56 when viewed from the Y direction. In other words, the protrusion 60 is integrally provided on the surface of the motor main body 56 facing the Y2 direction. Note that the protrusion 60 may protrude further in the Y1 direction than the motor main body 56. As shown in FIG. 4 , a motor connector 62 is provided on the surface of the protrusion 60 facing the X2 direction. The motor connector 62 is connected to the external connector 26 via a connection cable (not shown).

[0020] 7 and 9 , the pair of guide rods 38 guide the pair of movable members 40 in the X direction. The pair of guide rods 38 are arranged side by side in the Y direction. The guide rods 38 extend in the X direction along the rotation shaft 58 of the motor 34. The ends of the guide rods 38 are passed through the rod support holes 54 of the support member 32. The guide rods 38 are attached to the first support portion 48 by fastening members 63.

[0021] 7, 9, and 10, the axially intermediate portion of the guide rod 38 is supported by an intermediate support portion 64. The intermediate support portion 64 is fixed to the support member 32 by a plurality of fastening members 66. The intermediate support portion 64 is also fixed to the second cover member 18 by a fastening member 68 (see FIG. 10). The intermediate support portion 64 is formed with a pair of intermediate insertion holes 70 through which the pair of guide rods 38 pass.

[0022] As shown in Figures 7 and 9, the pair of movable members 40 move in the X direction by the power of the motor 34. The movable member 40 has a movable main body 72 and a pair of mounting portions 74. The movable main body 72 is formed in a plate shape. A pair of insertion holes 76, through which the pair of guide rods 38 are inserted, is formed in the movable main body 72. The pair of insertion holes 76 are arranged side by side and spaced apart from each other in the Y direction. As shown in Figure 9, two plain bearings 78 are arranged in each insertion hole 76. The plain bearings 78 are formed in annular shapes and fixed to the movable main body 72. The plain bearings 78 slide in the X direction relative to the guide rods 38. Note that only one plain bearing 78 may be arranged in each insertion hole 76.

[0023] 7, the pair of mounting portions 74 protrude in the Z2 direction from both Y-direction ends of the movable main body 72. The mounting portions 74 are formed with a plurality of mounting holes 80 for mounting the attachment 300 (see FIG. 2).

[0024] 8, the power transmission mechanism 42 transmits the power of the motor 34 to the pair of movable members 40. The power transmission mechanism 42 has a feed screw shaft 44, an intermediate member 82, and a pair of nuts 84.

[0025] The feed screw shaft 44 extends in the X direction along the rotation shaft 58. In the axial direction of the feed screw shaft 44, the overall length L3 of the motor 34 is shorter than the overall length L4 of the feed screw shaft 44. One end (the end in the X1 direction) of the feed screw shaft 44 is arranged parallel to the rotation shaft 58. The feed screw shaft 44 extends in the X2 direction further than the X2-direction end of the motor 34.

[0026] The end of the controller 36 opposite the motor 34 is located in the X direction between the other end (the end in the X2 direction) of the feed screw shaft 44 and the motor 34. The overall length L4 of the feed screw shaft 44 along the X direction is longer than the distance L5 in the X direction from the end of the motor 34 in the X1 direction to the end of the controller 36 in the X2 direction. In the axial direction of the feed screw shaft 44, the overall length L4 of the feed screw shaft 44 is shorter than the overall length L6 of the guide rod 38 (see FIG. 9 ).

[0027] The feed screw shaft 44 is rotatably supported by a pair of bearings 86 fixed to the second support portion 50. The bearings 86 are, for example, rolling bearings, but may also be plain bearings. As shown in FIGS. 7 and 8 , the feed screw shaft 44 includes a right-hand thread portion 88 and a left-hand thread portion 90. The right-hand thread portion 88 and the left-hand thread portion 90 are arranged spaced apart from each other in the X direction. In other words, no male thread is formed in the axial center portion of the feed screw shaft 44.

[0028] 6 and 8 , the intermediate member 82 transmits the rotational force of the motor 34 to the feed screw shaft 44. The intermediate member 82 has a first pulley 92, a second pulley 94, and a belt 96. The first pulley 92 is an annular member fixed to the rotary shaft 58. The second pulley 94 is an annular member fixed to one end (the end in the X1 direction) of the feed screw shaft 44. The belt 96 is formed in an annular shape and is wound around the first pulley 92 and the second pulley 94. The first pulley 92 and the second pulley 94 are arranged side by side in the Z direction. The intermediate member 82 may be formed, for example, by a plurality of gears.

[0029] As shown in Figures 7 and 8, a pair of nuts 84 are threadedly engaged with the right-hand threaded portion 88 and the left-hand threaded portion 90, respectively. The nut 84 includes a nut body 98 and a pair of pressing portions 100a, 100b. The nut body 98 has a rectangular outer shape. As shown in Figure 8, the nut body 98 is formed with a hole 102 through which the feed screw shaft 44 is inserted. The hole 102 is formed with a female thread that is threadedly engaged with the male thread of the feed screw shaft 44.

[0030] 7, the pair of pressing portions 100a, 100b are plate-shaped portions that protrude in the Z2 direction from the nut body 98. The pair of pressing portions 100a, 100b face each other while being spaced apart from each other in the X direction. The pressing portion 100a is located closer to the center of the feed screw shaft 44 in the axial direction than the pressing portion 100b.

[0031] As shown in Figures 7, 8, and 11, a pin member 104 is disposed between the pair of pressing portions 100a, 100b. The pin member 104 engages with the pair of pressing portions 100a, 100b. As shown in Figures 8 and 11, the pin member 104 is inserted into a retaining hole 106 formed on the surface of the movable main body 72 facing the Z1 direction. The pin member 104 is fixed to the movable main body 72 by a fastening member 108 while inserted into the retaining hole 106. The pin member 104 is located in the center of the movable main body 72 in the Y direction.

[0032] In the electric gripper 10A, when the rotation shaft 58 of the motor 34 rotates in the first rotation direction, the rotational force of the motor 34 is transmitted to the feed screw shaft 44 via the intermediate member 82 (first pulley 92, belt 96, and second pulley 94), causing the feed screw shaft 44 to rotate. When the feed screw shaft 44 rotates, the pair of nuts 84 move in directions approaching each other relative to the feed screw shaft 44. As a result, the pressing portions 100b of the nuts 84 press the pin members 104, causing the pair of movable members 40 to move in directions approaching each other. This allows the attachments 300 attached to the pair of movable members 40 to hold the workpiece.

[0033] On the other hand, when the rotary shaft 58 of the motor 34 rotates in a second rotation direction, which is the opposite direction to the first rotation direction, the feed screw shaft 44 rotates in the opposite direction. In this case, the pair of nuts 84 move in directions away from each other relative to the feed screw shaft 44. As a result, the pressing portions 100a of the nuts 84 press the pin members 104, and the pair of movable members 40 move in directions away from each other. This allows the attachment 300 to be separated from the workpiece.

[0034] According to the embodiment described above, the pair of movable members 40 slide relative to the guide rod 38 via the slide bearings 78, which allows for a simpler configuration than when the movable members are guided by a linear guide having a plurality of rolling elements (balls). This allows for a lighter weight electric gripper 10A. As a result, a good electric gripper 10A can be obtained.

[0035] Second Embodiment Next, an electric gripper 10B according to a second embodiment of the present invention will be described below with reference to the drawings. In the electric gripper 10B according to this embodiment, the same components as those of the electric gripper 10A described above are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that in this embodiment, the same components as those of the electric gripper 10A described above have the same effects.

[0036] As shown in Fig. 12, the electric gripper 10B is formed in a horizontally elongated (flat) shape. As shown in Figs. 12 to 14, the length (maximum length) L7 of the electric gripper 10B in the height direction (Z direction) is shorter than the length (maximum length) L8 of the electric gripper 10B in the thickness direction (Y direction). Therefore, the electric gripper 10B can be shortened in the height direction.

[0037] As shown in FIG. 15 , the electric gripper 10B includes a casing 12a and a gripper body 14a. The casing 12a houses the gripper body 14a. The casing 12a includes a first cover member 16a that covers the gripper body 14a from the Z1 direction and a second cover member 18a that covers the gripper body 14a from the Z2 direction. The first cover member 16a and the second cover member 18a are connected by a fastening member 20. An adapter 24 and an external connector 26 are attached to a first wall surface 22a of the first cover member 16a that faces the Z1 direction. A pair of elongated holes 30 extending in the width direction (X direction) are formed in a second wall surface 28a of the second cover member 18a that faces the Z2 direction (see FIG. 14 ).

[0038] 15 to 18, the gripper body 14a includes a support member 32, a motor 34, a controller 36, a pair of guide rods 38, a pair of movable members 40, and a power transmission mechanism 42. As shown in FIGS. 15 and 17, the adapter 24, the feed screw shaft 44, and the pair of guide rods 38 are arranged side by side in this order along the height direction. As shown in FIGS. 15, 16, and 18, the motor 34 and the feed screw shaft 44 are arranged side by side along the thickness direction (Y direction).

[0039] As shown in Figure 16, the motor body 56 is fixed to the support member 32 via a plate member 59a. The controller 36 has a protrusion 60 that protrudes further in the Y1 direction (the opposite side from the support member 32) than the motor body 56. The protrusion 60 extends in the X1 direction. A portion of the protrusion 60 overlaps with the motor body 56 when viewed from the Y direction. As shown in Figures 16 and 18, the rotation shaft 58 of the motor 34 is arranged in the Y direction alongside one end (the end in the X1 direction) of the feed screw shaft 44.

[0040] In addition to the above disclosure, the following additional notes are disclosed.

[0041] (Supplementary Note 1) The electric gripper (10A, 10B) includes a motor (34), a pair of movable members (40) for gripping a workpiece, a guide rod (38) for guiding the pair of movable members, and a power transmission mechanism (42) for transmitting the power of the motor to the pair of movable members to move the pair of movable members toward and away from each other along the guide rod, and each of the pair of movable members is provided with a plain bearing (78) that slides relative to the guide rod.

[0042] According to this configuration, the pair of movable members slide relative to the guide rod via the slide bearing, which allows for a simpler configuration than when the movable members are guided by a linear guide having multiple rolling elements (balls). This allows for a lighter electric gripper. As a result, a good electric gripper can be obtained.

[0043] (Supplementary Note 2) The electric gripper according to Supplementary Note 1 may further include support members (32) that support both ends of the guide rod.

[0044] According to this configuration, the support member can prevent the guide rod from bending when the workpiece is gripped via the pair of movable members.

[0045] (Supplementary Note 3) In the electric gripper according to Supplementary Note 2, an intermediate support portion (64) that supports an axial intermediate portion of the guide rod may be attached to the support member.

[0046] With this configuration, the deflection of the guide rod can be further suppressed by the intermediate support portion.

[0047] (Appendix 4) In the electric gripper described in any one of Appendices 1 to 3, the guide rods may be provided in pairs, the movable member may be formed with a pair of insertion holes (76) through which the pair of guide rods are inserted, and the plain bearing may be disposed in each of the pair of insertion holes.

[0048] With this configuration, the movable member can be smoothly guided along the pair of guide rods.

[0049] (Supplementary Note 5) In the electric gripper described in any one of Supplementary Notes 1 to 4, the power transmission mechanism may include a feed screw shaft (44) that rotates by the power of the motor and includes a right-handed thread portion (88) and a left-handed thread portion (90), and a pair of nuts (84) that are threaded onto the right-handed thread portion and the left-handed thread portion, respectively, and the pair of movable members may be moved by being pushed in the axial direction of the guide rod by the pair of nuts while being supported by the guide rod.

[0050] According to this configuration, the power transmission mechanism can be simplified, and therefore the electric gripper can be made compact.

[0051] (Appendix 6) In the electric gripper described in Appendix 5, each of the pair of nuts may have a pair of pressing portions (100a, 100b) arranged to face each other while being spaced apart from each other in the axial direction of the feed screw shaft, and each of the pair of movable members may have a pin member (104) attached to it so as to be arranged between the pair of pressing portions.

[0052] With this configuration, the movable member can be moved by pressing the pin member with the pressing portion of the nut. In this case, the movable member can be disposed close to the nut, and the pressing force of the pressing portion can be efficiently transmitted to the movable member. In addition, the electric gripper can be made compact.

[0053] (Supplementary Note 7) In the electric gripper described in Supplementary Note 5, the motor, the feed screw shaft, and the guide rod may be arranged in this order along a height direction perpendicular to the rotation axis (58) of the motor.

[0054] With this configuration, the length of the electric gripper in the thickness direction can be shortened.

[0055] (Supplementary Note 8) The electric gripper according to Supplementary Note 7 may further include an adapter (24) that is detachable from a robot arm, and the adapter, the motor, the feed screw shaft, and the guide rod may be arranged in this order along the height direction.

[0056] With this configuration, the length of the electric gripper in the thickness direction can be shortened.

[0057] (Supplementary Note 9) In the electric gripper described in Supplementary Note 7 or 8, the length (L1) of the electric gripper in the height direction may be longer than the length (L2) of the electric gripper in a thickness direction perpendicular to the height direction.

[0058] With this configuration, the length of the electric gripper in the thickness direction can be shortened.

[0059] (Appendix 10) In the electric gripper described in any one of Appendices 5 to 9, the feed screw shaft and the guide rod may be arranged side by side along a height direction perpendicular to a rotation axis of the motor, and the motor and the feed screw shaft may be arranged side by side along a thickness direction perpendicular to the height direction.

[0060] With this configuration, the height of the electric gripper can be reduced.

[0061] (Supplementary Note 11) The electric gripper according to Supplementary Note 10 may further include an adapter detachable from a robot arm, and the adapter, the feed screw shaft, and the guide rod may be arranged side by side in this order along the height direction.

[0062] With this configuration, the length of the electric gripper in the thickness direction can be reduced.

[0063] (Supplementary Note 12) In the electric gripper according to Supplementary Note 10 or 11, the length (L7) of the electric gripper in the height direction may be shorter than the length (L8) of the electric gripper in the thickness direction.

[0064] With this configuration, the height of the electric gripper can be reduced.

[0065] (Appendix 13) In the electric gripper described in any one of Appendices 7 to 12, the power transmission mechanism includes a first pulley (92) provided on the rotating shaft, a second pulley (94) provided on one end of the feed screw shaft, and a circular belt (96) wound around the first pulley and the second pulley, and the first pulley and the second pulley may be arranged side by side.

[0066] With this configuration, the power of the motor can be efficiently transmitted to the feed screw shaft while keeping the power transmission mechanism compact.

[0067] (Supplementary Note 14) In the electric gripper according to Supplementary Note 13, a total length (L3) of the motor may be shorter than a total length (L4) of the feed screw shaft in an axial direction of the feed screw shaft.

[0068] With this configuration, the length of the electric gripper in the axial direction of the feed screw shaft can be shortened.

[0069] (Supplementary Note 15) In the electric gripper described in Supplementary Note 14, the motor has a motor body (56) and the rotation shaft protruding from the motor body, and a controller (36) for controlling the motor may be integrally provided on a surface of the motor body facing away from the rotation shaft.

[0070] With this configuration, the electric gripper can be made smaller than when the motor and the controller are arranged separately.

[0071] (Supplementary Note 16) In the electric gripper according to Supplementary Note 15, an end of the controller opposite to the motor may be located between the other end of the feed screw shaft and the motor.

[0072] With this configuration, the length of the electric gripper in the axial direction of the feed screw shaft can be shortened.

[0073] (Supplementary Note 17) In the electric gripper according to Supplementary Note 16, the controller may have a protruding portion (60) that protrudes beyond the motor body to one side in a thickness direction perpendicular to the height direction.

[0074] According to this configuration, the protruding portion of the controller protrudes in the thickness direction beyond the motor body, so that the height of the controller can be reduced.

[0075] (Supplementary Note 18) In the electric gripper according to Supplementary Note 17, a part of the protrusion may overlap with the motor body when viewed in the thickness direction.

[0076] With this configuration, the height of the controller can be further reduced.

[0077] (Supplementary Note 19) In the electric gripper according to any one of Supplementary Notes 7 to 12, the overall length of the feed screw shaft in the axial direction of the feed screw shaft may be shorter than the overall length (L6) of the guide rod.

[0078] With this configuration, the length of the electric gripper in the axial direction of the feed screw shaft can be shortened.

[0079] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention.

[0080] DESCRIPTION OF SYMBOLS 10A, 10B... Electric gripper 24... Adapter 32... Support member 34... Motor 36... Controller 38... Guide rod 40... Movable member 42... Power transmission mechanism 44... Feed screw shaft 56... Motor body 58... Rotating shaft 60... Protrusion 64... Intermediate support portion 76... Insertion hole 78... Slide bearing 84... Nut 88... Right-handed thread portion 90... Left-handed thread portion 92... First pulley 94... Second pulley 96... Belt 100a, 100b... Pressing portion 104... Pin member

Claims

1. An electric gripper (10A, 10B) comprising: a motor (34); a pair of movable members (40) for gripping a workpiece; a guide rod (38) for guiding the pair of movable members; and a power transmission mechanism (42) for transmitting the power of the motor to the pair of movable members to move the pair of movable members toward and away from each other along the guide rod, wherein each of the pair of movable members is provided with a plain bearing (78) that slides relative to the guide rod.

2. The electric gripper according to claim 1, further comprising a support member (32) for supporting both ends of the guide rod.

3. An electric gripper according to claim 2, wherein an intermediate support portion (64) for supporting an axial intermediate portion of the guide rod is attached to the support member.

4. An electric gripper as described in claim 1, wherein a pair of the guide rods are provided, a pair of insertion holes (76) are formed in the movable member through which the pair of guide rods pass, and the sliding bearings are disposed in each of the pair of insertion holes.

5. An electric gripper as described in claim 1, wherein the power transmission mechanism comprises: a feed screw shaft (44) that rotates by the power of the motor and includes a right-handed thread portion (88) and a left-handed thread portion (90); and a pair of nuts (84) that screw into the right-handed thread portion and the left-handed thread portion, respectively; and wherein the pair of movable members are moved by being pushed in the axial direction of the guide rod by the pair of nuts while supported by the guide rod.

6. An electric gripper as claimed in claim 5, wherein each of the pair of nuts has a pair of pressing portions (100a, 100b) arranged to face each other while being spaced apart from each other in the axial direction of the feed screw shaft, and a pin member (104) is attached to each of the pair of movable members so as to be positioned between the pair of pressing portions.

7. An electric gripper according to claim 5, wherein the motor, the feed screw shaft, and the guide rod are arranged in this order along a height direction perpendicular to the rotation axis (58) of the motor.

8. An electric gripper as claimed in claim 7, further comprising an adapter (24) that is detachable from a robot arm, the adapter, the motor, the feed screw shaft and the guide rod being arranged in parallel in this order along the height direction.

9. An electric gripper according to claim 7, wherein the length (L1) of the electric gripper in the height direction is longer than the length (L2) of the electric gripper in a thickness direction perpendicular to the height direction.

10. An electric gripper as described in claim 5, wherein the feed screw shaft and the guide rod are arranged side by side along a height direction perpendicular to the rotation axis of the motor, and the motor and the feed screw shaft are arranged side by side along a thickness direction perpendicular to the height direction.

11. An electric gripper according to claim 10, further comprising an adapter that is detachable from a robot arm, the adapter, the feed screw shaft, and the guide rod being arranged in parallel in this order along the height direction.

12. The electric gripper according to claim 10, wherein the length (L7) of the electric gripper in the height direction is shorter than the length (L8) of the electric gripper in the thickness direction.

13. An electric gripper according to any one of claims 7 to 12, wherein the power transmission mechanism includes a first pulley (92) provided on the rotating shaft, a second pulley (94) provided at one end of the feed screw shaft, and a circular belt (96) wound around the first pulley and the second pulley, and the first pulley and the second pulley are arranged side by side.

14. The electric gripper according to claim 13, wherein the overall length (L3) of the motor in the axial direction of the feed screw shaft is shorter than the overall length (L4) of the feed screw shaft.

15. An electric gripper as described in claim 14, wherein the motor has a motor body (56) and a rotation shaft protruding from the motor body, and a controller (36) for controlling the motor is integrally provided on a surface of the motor body facing away from the rotation shaft.

16. The electric gripper according to claim 15, wherein an end of the controller opposite to the motor is located between the other end of the feed screw shaft and the motor.

17. An electric gripper according to claim 16, wherein the controller has a protruding portion (60) that protrudes beyond the motor body to one side in a thickness direction perpendicular to the height direction.

18. The electric gripper according to claim 17, wherein a portion of the protrusion overlaps with the motor body when viewed in the thickness direction.

19. An electric gripper according to any one of claims 7 to 12, wherein the overall length of the feed screw shaft in the axial direction of the feed screw shaft is shorter than the overall length (L6) of the guide rod.

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