Electric Hand Mechanism

Abstract

To provide an electrically-driven hand mechanism of which axial dimensions are suppressed.SOLUTION: An electrically-driven hand mechanism 100 comprises: a nut 4 which has an inner peripheral surface formed with a female screw part engaging with a male screw part formed on a rotary shaft of a rotating electric machine, and a plurality of arm parts 4a projecting to a radial outer side from an outer peripheral surface thereof formed at regular intervals in a circumferential direction; and substantially L-shaped fingers 6 with the same number of the arm parts. One end parts of the plurality of fingers are joined to the plurality of arm parts respectively by first link pins 5, and bent parts of the plurality of fingers are joined to stationery bodies 3a by second link pins 7.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an electric hand mechanism. [Background technology]

[0002] The electric gripper described in Patent Document 1 has a drive mechanism including a gripper unit that grips a workpiece, a motor that is a drive source for opening and closing the gripper unit, a link mechanism that opens and closes the gripper unit, and a feed screw unit that transmits a rotational drive force from the motor to a pair of link members that constitute the link mechanism. The feed screw unit has a threaded shaft whose one end is coaxially fitted onto the drive shaft of the motor and whose outer circumferential surface is formed with a male thread, a feed nut whose inner circumferential surface is formed with a female thread and which is screwed onto the other end of the threaded shaft, and a guide cylinder that houses the feed nut so that it can slide axially. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4737456 Summary of the Invention [Problem to be solved by the invention]

[0004] In a conventional electric gripper, a link mechanism for opening and closing the gripper unit is arranged so as to be aligned in the axial direction with a guide tube that houses a feed nut so as to be slidable in the axial direction, which tends to increase the axial dimension of the electric gripper.

[0005] In view of the above circumstances, an object of the present invention is to provide an electric hand mechanism having a reduced axial dimension. [Means for solving the problem]

[0006] The electric hand mechanism according to the present invention includes a nut having an internal thread formed on an inner circumferential surface thereof, the internal thread being adapted to screw into an external thread formed on a rotating shaft of a rotating electric machine, and having a number of arms protruding radially outward from an outer circumferential surface thereof at equal intervals in the circumferential direction, and substantially L-shaped fingers, the number of which is the same as the number of the arms, one end of each of the fingers being joined to the respective arms by a first link pin, and bent portions of the fingers being joined to a stationary body by a second link pin. The nut is restricted in rotation and is movable in the axial direction. . Effect of the Invention

[0007] According to the present invention, it is possible to provide an electric hand mechanism having a reduced axial dimension. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a plan view of the three-jaw electric hand. [Diagram 2] 2 is a cross-sectional view taken along line A1-A1 of FIG. 1. [Diagram 3] FIG. 2 is a plan view of the three-jaw electric hand with the cover removed. [Figure 4] FIG. 2 is a perspective view of the three-jaw electric hand mechanism with the cover removed. [Diagram 5] FIG. 2 is a side view of the three-jaw electric hand mechanism with the cover removed. [Figure 6] FIG. 2 is a plan view of the four-jaw electric hand mechanism. [Figure 7] FIG. 2 is a side view of the four-jaw electric hand mechanism. [Figure 8] FIG. 2 is a plan view of the four-jaw electric hand mechanism with the cover removed. [Figure 9] FIG. 2 is a side view of the four-jaw electric hand mechanism with the cover removed. [Figure 10] FIG. 2 is a perspective view of the four-jaw electric hand mechanism with the cover removed. [Figure 11] FIG. 2 is a plan view of the two-jaw electric hand mechanism. [Figure 12] 12 is a cross-sectional view taken along line A2-A2 of FIG. 11. [Figure 13] FIG. 2 is a perspective view of the two-jaw electric hand mechanism with the cover removed. [Figure 14] FIG. 1 is a plan view of a parallel movement type two-jaw electric hand mechanism. [Figure 15] 15 is a cross-sectional view taken along line A3-A3 in FIG. 14. [Figure 16] FIG. 2 is a plan view of the two-jaw electric hand mechanism. [Figure 17] 17 is a cross-sectional view taken along line A4-A4 in FIG. 16. [Figure 18] 17 is a cross-sectional view taken along line A5-A5 in FIG. 16. [Figure 19] FIG. 18 is a partially enlarged view of FIG. [Figure 20] FIG. 4 is an explanatory diagram of forces acting on a rotating shaft. [Figure 21] FIG. 13 is a plan view of the nut of the two-jaw electric hand mechanism screwed onto the rotating shaft. [Figure 22] 22 is a cross-sectional view taken along line A6-A6 in FIG. 21. [Diagram 23] FIG. 23 is a partially enlarged view of FIG. 22. [Figure 24] FIG. 24 is a partially enlarged view of FIG. 23. [Diagram 25] FIG. 2 is a side view of the two-jaw electric hand mechanism. [Figure 26] FIG. 2 is a side view of a three-jaw electric hand mechanism attached to a motor. [Figure 27] FIG. 1 is a side view of a parallel movement type two-jaw electric hand mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0010] <First embodiment (three-jaw electric hand)> 1 to 5, a three-jaw electric hand mechanism 100 is attached to a motor 1. The details will be described below.

[0011] The housing of the motor 1 has an external shape that is roughly a rectangular parallelepiped, and a rotating shaft 2 of the motor 1 protrudes from a hole formed in one surface (called the "mounting surface") of the housing. The tip of the rotating shaft 2 is provided with a threaded shaft portion 2a having a male screw formed on the outer circumferential surface.

[0012] The three-jaw electric hand mechanism 100 includes a base portion 3, a nut 4, fingers 6, and claws 8. The base portion 3 is generally plate-shaped, and is attached to a mounting surface of the housing of the motor 1 so as to face the same in the axial direction. A hole is formed in the base portion 3, and the rotating shaft 2 passes through the hole. Three finger support portions 3a extending in approximately the same direction as the protruding direction of the rotating shaft 2 are provided at equal intervals in the circumferential direction on the surface of the base portion 3 opposite the surface facing the motor 1.

[0013] The nut 4 is generally cylindrical, and has an internal thread formed on its inner circumferential surface to receive the external thread of the screw shaft portion 2a. On the outer circumferential surface of the nut 4, three arms 4a protruding radially outward are provided at equal intervals in the circumferential direction. The three arms 4a correspond in circumferential position to the three finger support portions 3a, respectively. The radial position of each of the three arms 4a is located inside the radial position of the corresponding finger support portion 3a.

[0014] The three fingers 6 are all of the same size, have a generally L-shaped outer shape, and have a base end 6a, a bent portion, and a tip end 6b. They extend generally radially outward from the base end to the bent portion, and extend generally in the same direction as the protruding direction of the rotating shaft 2 from the bent portion to the tip end 6b.

[0015] A radially long slot is drilled in the approximate circumferential direction in each of the three base ends 6a. A hole is drilled in the approximate circumferential direction in each of the three arm portions 4a, and the radial position of the hole is approximately the same as that of the slot. A link pin 5 is provided so as to pass through the hole in the arm portion 4a of the nut 4 and the slot in the base end portion 6a of the finger 6. The base end portion 6a is joined to the arm portion 4a so as to be swingable around the link pin 5.

[0016] A hole is drilled in the approximate circumferential direction in the bent portion of each of the three fingers 6. A hole is drilled in the approximate circumferential direction in each of the three finger support portions 3a, and the hole is located in the radial direction and coincides with the hole in the bent portion of the finger 6. A finger opening / closing pin 7 is provided so as to penetrate the hole in each finger support portion 3a and the hole in the bent portion of the finger 6 corresponding to that finger support portion. The bent portion of the finger 6 is joined to the finger support portion 3a, which is a stationary body, so as to be swingable around the finger opening / closing pin 7.

[0017] A claw 8 extending in substantially the same direction as the protruding direction of the rotary shaft 2 is attached to each of the tip portions 6b of the three fingers 6.

[0018] A cover portion 3b is attached to the base portion 3 so as to cover the rotating shaft 2 protruding from the hole in the base portion 3, the nut 4, the finger support portion 3a, and the base end portion 6a and bent portion of the finger 6. This cover portion 3b is substantially cylindrical and has one axial end closed. An opening is formed in the closed portion so that the portion of the finger 6 beyond the bent portion can pass through.

[0019] Next, the operation of the three-jaw electric hand mechanism 100 will be described. The nut 4 that screws onto the threaded shaft portion 2a of the rotating shaft 2 has three fingers 6 connected to three finger support portions 3a arranged at equal intervals in the circumferential direction on three arm portions 4a via finger opening / closing pins 7. Furthermore, the three fingers 6 and the three arm portions 4a of the nut 4 are each connected via a link pin 5. In this way, the rotation of the nut 4 is restricted. When the rotating shaft 2 rotates in one circumferential direction by the drive of the motor 1, the nut 4 is displaced in one axial direction, and when the rotating shaft 2 rotates in the other circumferential direction, the nut 4 is displaced in the other axial direction.

[0020] When the nut 4 reciprocates in the axial direction, the tips 6b of the three fingers 6 connected to the arm 4a via the link pin 5 reciprocate in the approximate radial direction (in the directions of the arrows Y1 and Y2) with the finger opening / closing pin 7 as a fulcrum. The three fingers move radially outward (in the direction of the arrow Y1) and radially inward (in the direction of the arrow Y2) at the same time. The three claws 8 are opened and closed by such reciprocating motion of the three fingers 6. In this way, the opening and closing motion of the three-claw electric hand mechanism is realized by driving the single motor 2.

[0021] According to the above embodiment, the nut 4 is screwed onto the threaded shaft portion 2a of the rotating shaft 2, and the fingers 6 supported by the finger support portion 3 are joined to the arm portion 4a of the nut 4. Therefore, the radial center position of the nut 4 is maintained, and the nut 4 can move smoothly in the axial direction.

[0022] <Second embodiment (four-jaw electric hand)> 6 to 10 show a four-jaw electric hand mechanism 200 which is a modification of the three-jaw electric hand mechanism 100 according to the first embodiment. Reference symbol X (X is any of the reference symbols shown in Figs. 1 to 5) in the three-jaw electric hand mechanism 100 corresponds to reference symbol 20X in the four-jaw electric hand mechanism 200. Four arm portions 204a protruding radially outward are provided at equal intervals in the circumferential direction on the outer circumferential surface of the nut 204. Four finger support portions 203a are provided at equal intervals in the circumferential direction. In this four-jaw electric hand mechanism 200 as well, the radial center position of the nut 204 is maintained and the axial movement of the nut 204 is smooth.

[0023] <Third embodiment (two-jaw electric hand)> 11 to 13 show the two-jaw electric hand mechanism 300. The reference symbol X (X is any of the reference symbols shown in Figs. 1 to 5) in the three-jaw electric hand mechanism 100 corresponds to the reference symbol 30X in the two-jaw electric hand mechanism 300. Two arms 304a that protrude radially outward are provided at equal intervals in the circumferential direction on the outer circumferential surface of the nut 304. Two finger support parts 303a are provided at equal intervals in the circumferential direction. The two-jaw electric hand mechanism 300 basically operates in the same way as the three-jaw electric hand mechanism 100, and the radial center position of the nut 304 is maintained, allowing smooth axial movement of the nut 304.

[0024] Finger 306 is L-shaped with a bent portion and moves around the bent portion as a fulcrum. Therefore, the direction in which tip 306b of finger 306 and claw 308 attached to the tip move is not parallel to the radial direction of rotation shaft 2.

[0025] Unlike the three-jaw electric hand mechanism 100 and the four-jaw electric hand mechanism 200, in the two-jaw electric hand mechanism 300, the threaded shaft portion 2a balances the two fingers 306. Therefore, the threaded shaft portion 2a needs to have the strength to balance the two fingers 306. The strength of the threaded shaft portion 2a need only be sufficient to withstand the gripping force of the fingers 306. Due to the strength of this threaded shaft portion 2a, a guide tube that houses the nut so that it can slide freely in the axial direction, which was previously necessary, can be omitted in this structure.

[0026] <Fourth embodiment (parallel movement type two-jaw electric hand)> 14 and 15 show a parallel movement type two-jaw hand mechanism 400 in which two jaws 413 move parallel to the radial direction of the rotation shaft 2. Reference numerals 403 to 405 correspond to reference numerals 303 to 305 of the two-jaw electric hand mechanism 300 according to the third embodiment. The L-shaped finger 306 of the two-jaw hand mechanism 300 is replaced with an L-shaped intermediate hinge 406 in the two-jaw electric hand mechanism 400. The operation up to this intermediate hinge 406 is the same as that of the two-jaw hand mechanism 300 shown in FIGS. 11 to 13.

[0027] The intermediate hinge 406 has a base end joined to the arm portion of the nut 404 via a link pin 405, and a bent portion joined to the finger support portion 403a via a pin 407. A base portion of a parallel finger 410 extending in the same direction as the protruding direction of the rotating shaft 2 is joined to a tip portion of the intermediate hinge 406 via a finger connecting pin 408 extending in a substantially circumferential direction. A claw 413 is attached to the tip portion of the parallel finger 410.

[0028] The parallel fingers 410 are fastened to a guide block 412, and the guide block 412 moves along a guide rail 411 provided parallel to the radial direction of the rotating shaft 2. The guide rail 411 is fastened to a guide base 409, and the guide base 409 is fastened to the base portion 403.

[0029] As a result, when the rotating shaft 2 and the screw shaft portion 2 a rotate, power is transmitted to the fingers 410 through the nut 404 , and the fingers 410 and the claws 413 perform opening and closing movements parallel to the radial direction of the rotating shaft 2 .

[0030] 16 to 20 again show the non-translation type two-jaw electric hand mechanism 300. A case where a workpiece to be grasped is to be grasped by this two-jaw electric hand mechanism 300 will be described below.

[0031] When both of the two claws 308 are in contact with the workpiece and the force LF applied to one claw 308 and the force RF applied to the other claw 308 are balanced, no biased load that would cause the nut 304 to tilt in the axial direction is applied to the nut 304. In contrast, when one of the claws 308 is in contact with the workpiece and the other claw 308 is not in contact with the workpiece, a biased load that would cause the nut 304 to tilt in the axial direction is applied to the nut 304.

[0032] For example, when a force LF is applied to the claw 308 on the left side of the paper in Fig. 17 and a force RF is not applied to the claw 308 on the right side of the paper, a force is transmitted from the finger 306 on the left side of the paper to the link pin 305 on the left side of the paper, with the finger opening / closing pin 307 on the left side of the paper as the fulcrum. This force is shown by vector F in Fig. 19. As shown in Fig. 20, vector F can be divided into a radial vector Fx (=Fcosθ) and an axial vector Fy (=Fsinθ). The angle θ between vector F and the radial direction changes depending on the position of the nut 304, and the magnitude of vector F changes accordingly. Therefore, when angle θ is minimum, radial force Fx is maximum.

[0033] However, when the angle θ is at its maximum, the axial distance L from the fulcrum O (the center of the boundary surface between the rotating shaft 2 and the screw shaft portion 2a) supporting the screw shaft 2a to the starting point of the vector F is relatively large, so the amount of deflection of the rotating shaft 2 may be large.

[0034] Therefore, it is necessary to check the amount of deflection of the rotating shaft 2 at both the minimum and maximum angles θ. The amount of deflection also depends on the material and thickness of the rotating shaft 2. In addition to the material, the amount of deflection of the rotating shaft 2 can be reduced by using a material with a high Young's modulus. In reality, if hard materials such as iron or stainless steel are used for the rotating shaft 2, the amount of deflection can be reduced.

[0035] The amount of deflection of the rotating shaft 2 is calculated by the following formula.

number

[0036] The attitude of the nut 304 will be described with reference to FIGS. The thread gap H between the nut 304 and the screw shaft portion 2a affects the attitude of the nut 304. The larger the gap H, the more the nut 304 will tilt in a direction substantially opposite to the direction of the applied load when a load is applied from one of the pawls 308. When a force LF is applied to one of the pawls 308, the nut will tilt in the direction of the vector F. In order to eliminate or reduce this inclination, conventional hands are provided with a guide cylinder that houses the nut so that it can slide axially.

[0037] In contrast, the electric hand mechanism according to the embodiment of the present invention maintains the nut's posture by minimizing the gap H between the nut and the screw shaft as well as the strength of the screw shaft. If the gap H is 0.005 mm to 0.02 mm, the grease circulates well and the nut can be displaced smoothly without getting caught. In addition, by installing the link pin 305 as close to the screw shaft as possible, the inclination of the nut can be minimized. As shown in FIG. 22 as an example, the center distance R305 of the two link pins 305 is 2.5 times the effective diameter R2a of the screw shaft portion 2a. For example, in the case of a gap nozzle with a gap H of 0.01 mm, the link pin portion of the nut is inclined at an angle of about 0.025 (=0.01×2.5) mm, which is a guide accuracy close to that in the case of a guide tube. Furthermore, when the gap H is 0.005 mm, the inclination is 0.0125 (=0.005×2.5) mm, which is approximately the same accuracy as when guided by a guide tube. By moving the link pin closer to the center of the screw shaft, the effect of the gap between the screw and the nut is further reduced, making it possible to guide the nut's position with high precision without the need for a guide tube.

[0038] In addition, if the lead angle of the screw shaft 2a is 45 degrees or less, the self-locking mechanism will function to prevent the nut from moving due to external forces. In other words, even when the motor is turned off or there is a power outage, the finger position is maintained, so the workpiece to be gripped will not fall.

[0039] The lead of the screw shaft can also be changed depending on the purpose. If you want to increase the speed, you can increase the feed amount of the lead. Or, if you need resolution or gripping force, you can decrease the lead.

[0040] Figure 25 again shows the non-parallel movement type two-jaw electric hand mechanism 300, Figure 26 again shows the three-jaw electric hand mechanism 100, and Figure 27 again shows the parallel movement type two-jaw electric hand mechanism 400. If the inlays and mounting dimensions of the motor 1 and the specifications of the screw shaft portion 2a are common, the electric hand mechanisms 100, 300 and 400 and the four-jaw electric hand mechanism 200 can be selectively attached to the same motor 1. By sharing the motor and standardizing the mounting dimensions and specifications of the screw shaft portion, it is possible to select an electric hand mechanism according to the purpose and use it in combination with the motor.

[0041] As described above, according to the above embodiment of the present invention, the following effects can be obtained. (1) A guide tube for housing the nut so that it can slide axially is no longer necessary, resulting in a compact electric hand mechanism. (2) By providing the first link mechanism radially outside the nut, an electric hand mechanism with a compact axial dimension can be realized. (3) By matching the specifications of the mounting and screw parts to the same motor, it is possible to select and install any of the electric hand mechanisms from a series consisting of multiple electric hand mechanisms (three-jaw electric hand mechanism, four-jaw electric hand mechanism, non-parallel movement type two-jaw electric hand mechanism, and parallel movement type two-jaw electric hand mechanism).

[0042] Regarding the embodiments described above, the following supplementary notes are disclosed. [Appendix 1] a nut having an internal thread formed on an inner circumferential surface thereof, the internal thread being adapted to screw into an external thread formed on a rotating shaft of a rotating electric machine, and having a plurality of arms protruding radially outward from an outer circumferential surface thereof at equal intervals in a circumferential direction; The number of approximately L-shaped fingers is the same as the number of the arms. Equipped with One end of each of the fingers is connected to each of the arm portions by a first link pin, and a bent portion of each of the fingers is connected to a stationary body by a second link pin. Electric hand mechanism. [Appendix 2] 2. The electric hand mechanism according to claim 1, further comprising a plurality of claw portions attached to the tips of the plurality of fingers, respectively. [Appendix 3] A series of electric hand mechanisms comprising a plurality of electric hand mechanisms according to appended claim 1, each of which has a different number of arms and fingers, and which are configured so that the plurality of electric hand mechanisms can be attached to a rotating shaft of the same rotating electric machine.

[0043] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications and changes can be made based on the technical concept of the present invention. [Explanation of symbols]

[0044] 1 Motor 2 Rotation Axis 2a Screw shaft 3, 203, 303, 403 Base 3a, 203a, 303a, 403a Finger support 3b, 203b, 303b, 403b Cover part 4, 204, 304, 404 Nut 4a, 204a, 304a, 404a arm 5, 205, 305, 405 link pin 6, 206, 306 Fingers 6a Proximal end 6b Tip 7, 207, 307 Finger opening and closing pin 8, 208, 308 Claws

Claims

1. a nut having an internal thread formed on an inner circumferential surface thereof, the internal thread being adapted to screw into an external thread formed on a rotating shaft of a rotating electric machine, and having a plurality of arms protruding radially outward from an outer circumferential surface thereof at equal intervals in a circumferential direction; A number of approximately L-shaped fingers equal to the number of the arms; Equipped with One end of each of the fingers is connected to each of the arm portions by a first link pin, and a bent portion of each of the fingers is connected to a stationary body by a second link pin, so that the nut is restricted in rotation and is displaceable in the axial direction. Electric hand mechanism.

2. The electric hand mechanism according to claim 1 , further comprising a plurality of claws attached to the tips of the plurality of fingers, respectively.

3. A group of electric hand mechanisms comprising a plurality of electric hand mechanisms as described in claim 1, each of which has a different number of arms and fingers, and which are configured so that the plurality of electric hand mechanisms can be selectively attached to the rotating shaft of the same rotating electric machine.

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