JP7383915B2 - actuator - Google Patents

Description

The present disclosure relates to actuators.

Actuators that perform rotational motion and linear motion are known (see Patent Document 1). The actuator described in Patent Document 1 includes a ball screw and a ball spline, and uses a shaft member in which a screw shaft of the ball screw and a shaft of the ball spline are connected. In this configuration, the shaft member performs linear motion as the nut of the ball screw rotates, and the shaft member performs rotational motion as the spline outer cylinder of the ball spline rotates.

Moreover, the actuator of Patent Document 1 includes a two-shaft integrated motor. The two-shaft integrated motor includes a first rotor and a second rotor disposed radially outside the first rotor. A nut is fixed to the first rotor, and rotation of the nut causes the shaft member to perform linear motion. The shaft member rotates by the second rotor.

Japanese Patent Application Publication No. 2013-230076

Since the actuator of Patent Document 1 includes a two-shaft integrated motor in which the second rotor is disposed radially outside the first rotor, it may be difficult to reduce the footprint.

The present disclosure has been made in view of the above, and an object of the present disclosure is to provide an actuator that can have a small footprint and save space.

The actuator of the present disclosure includes a first motor having a first stator and a first rotor rotatable in a direction around a central axis relative to the first stator; a second motor that is spaced apart from each other in the axial direction of the shaft, has a second stator, and a second rotor that is rotatable relative to the second stator and coaxial with the central axis of the first rotor; and at least a portion of a first portion that passes through the first rotor and the second rotor along the axial direction and projects from the first rotor in one direction in the axial direction toward the opposite side of the two rotors. is provided with a spline groove portion extending along the axial direction, and a male screw portion is provided in at least a portion of the second portion that protrudes from the second rotor toward the opposite side of the first rotor in the other axial direction. A shaft member engages with the spline groove of the shaft member to guide the shaft member in the axial direction along the spline groove, and rotates together with the first rotor to guide the shaft member along the central axis. A nut that is provided with a spline outer cylinder that is rotatable in a direction around the axis, and a female threaded part that engages with the male threaded part of the shaft member, and that is rotatable together with the second rotor to move the shaft member in the axial direction of the central shaft. A member.

In the actuator, a spline outer cylinder, a first motor, a second motor, and a nut member are arranged along the axial direction of the central shaft. Therefore, compared to an actuator having a two-shaft integrated motor in which the second rotor is disposed radially outside the first rotor, the radial size is reduced and the footprint is smaller, so that space can be saved.

Furthermore, since the first motor and the second motor are separated, the torque of each motor can be set individually. Further, a spline outer cylinder is provided at one end of the shaft member, and a nut member is provided at the other end. Therefore, compared to the case where both the spline outer cylinder and the nut member are provided on one end side of the shaft member, the deflection and inclination of the shaft member due to the rotation of the spline outer cylinder and the nut member are reduced.

As a desirable form, the diameter of the spline groove in the shaft member is larger than the diameter of the male thread.

The driving force of the first motor rotates the spline outer cylinder in a direction around the central axis, and the shaft member rotates together with the spline outer cylinder. Here, since the diameter of the spline groove in the shaft member is larger than the diameter of the male thread, the rigidity of the spline groove is higher than that of the male thread. Therefore, when the shaft member is rotated and stopped at a predetermined position in the circumferential direction, it can be stopped at a position closer to the predetermined position. Moreover, when the shaft member is rotated until it reaches a predetermined position in the circumferential direction, the time required to finally position the shaft member at the predetermined position is shortened.

As a desirable form, the shaft member is divided into a shaft including the first portion and a screw shaft including the second portion, and the shaft and the screw shaft are connected via a connecting member.

As a result, when wear or the like occurs on the shaft or screw shaft, only the worn member of the shaft or screw shaft needs to be replaced, so it is possible to reduce parts costs.

Preferably, the first motor and the second motor are direct drive motors.

A direct drive motor directly transmits the generated driving force to an object without using a speed reduction mechanism. That is, the shaft member can be rotated by directly rotating the spline outer cylinder using the driving force of the first motor. Further, by directly rotating the nut member using the driving force of the second motor, the shaft member can be moved in a linear manner.

As a desirable form, an arm attachment member is fixed to the end of the first portion of the shaft member, and the arm attachment member supports an arm portion to which a workpiece is attached.

Since the first portion of the shaft member is provided with a spline outer cylinder that engages with the spline groove, deflection and inclination are reduced when the shaft member rotates. Therefore, vibration and inclination when the arm mounting member and the arm portion rotate are also reduced, so that the workpiece can be stably rotated and raised and lowered.

A desirable form includes a collet through which the second portion of the shaft member passes, a piston through which the second portion of the shaft member passes, a cylinder tube that accommodates the piston, and an elastic member that biases the piston. a clamping mechanism including a cylinder having a cylinder tube, the piston having a chuck portion that presses the collet against the shaft member by contacting the outer peripheral surface of the collet with the elastic member, and the collet having a chuck portion that presses the collet against the shaft member; When gas or liquid is supplied into the interior of the shaft member, it separates from the shaft member.

According to this configuration, the elastic member can urge the chuck portion to come into contact with the outer circumferential surface of the collet. The chuck section can press the collet against the shaft member and clamp the shaft member. Further, since the chuck portion is configured to be in contact with the outer circumferential surface of the collet, it overlaps with the outer circumferential surface in the radial direction. With this configuration, the axial dimension of the clamp mechanism can be reduced. Furthermore, the shaft member can be unclamped by supplying gas or liquid to the inside of the cylinder tube. Further, even when the power is cut off, the shaft member can be held by the clamp mechanism.

As a desirable form, the outer circumferential surface is a tapered surface whose diameter decreases as it approaches the chuck portion, and the chuck portion is an inclined surface facing the outer circumferential surface.

According to this configuration, the inclined surface can make surface contact with the tapered surface when no gas or liquid is supplied to the inside of the cylinder tube. Thereby, the frictional force generated between the collet and the chuck part can be increased compared to the case where the outer circumferential surface of the collet and the chuck part are in line contact or point contact. Therefore, when the collet clamps the shaft member, it is possible to prevent the outer peripheral surface of the collet and the chuck portion from slipping.

As a desirable form, the radially outer side of the spline outer cylinder is supported by a spline outer cylinder housing via a rolling bearing.

When a shaft member that supports a workpiece receives a rotational moment from the workpiece, there is a possibility that the shaft member receives a force in a direction that tilts the shaft member with respect to the central axis. Here, the radially outer side of the spline outer cylinder is supported by the spline outer cylinder housing via a bearing. Therefore, displacement or vibration of the spline outer cylinder in the radial direction perpendicular to the axial direction of the central shaft is suppressed.

As a desirable form, a cylindrical gap is formed between the first part and a cylindrical part provided on an arm attachment member fixed to the tip of the first part and covering the outer periphery of the first part. .

Due to the cylindrical gap, a labyrinth structure is formed between the first portion and the outside of the cylindrical gap, so that the dustproof and waterproof properties of the inside of the arm mounting member are improved.

According to the present invention, it is possible to provide an actuator that can have a small footprint and save space.

FIG. 1 is a sectional view of the actuator of the first embodiment. FIG. 2 is a sectional view of the actuator of the first embodiment, showing a state in which the stroke of the shaft member is at the upper limit. FIG. 3 is a sectional view of the actuator of the second embodiment. FIG. 4 is a cross-sectional view of the actuator of the second embodiment, showing a state in which the stroke of the shaft member is at the upper limit. FIG. 5 is a sectional view of the actuator of the third embodiment. FIG. 6 is an enlarged cross-sectional view of the main part of FIG. FIG. 7 is an enlarged cross-sectional view of another essential part of FIG. FIG. 8 is a cross-sectional view of the actuator of the third embodiment, showing a state in which the stroke of the shaft member is at the upper limit. FIG. 9 is a sectional view of the actuator of the fourth embodiment. FIG. 10 is a sectional view of the actuator of the fourth embodiment, showing a state in which the stroke of the shaft member is at the upper limit.

Modes for carrying out the invention (embodiments) will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate.

[First embodiment]
FIG. 1 is a sectional view of the actuator of the first embodiment. The cross section of FIG. 1 is a cross section taken by a plane including central axes AX of a first rotor and a second rotor, which will be described later. FIG. 2 is a sectional view of the actuator of the first embodiment, showing a state in which the stroke of the shaft member is at the upper limit.

As shown in FIG. 1, the actuator 1 is used, for example, as a pick-and-place device. The actuator 1 includes an arm portion 80, a first motor M1, a second motor M2, a shaft member SF, a spline outer cylinder 61, and a nut member 51.

Hereinafter, the direction parallel to the Z direction, from the first motor M1 toward the arm section 80 will be referred to as an upper direction, and the direction from the arm section 80 toward the first motor M1 will be referred to as a lower direction. Further, the axial direction of the central axis AX of the arm portion 80 is the same as the Z direction.

The arm portion 80 is, for example, a cantilevered arm having only a single arm. The actuator 1 is fixed to a fixed base ST, for example, with the central axis AX of the arm portion 80 oriented in the Z direction. The arm portion 80 is fixed onto the arm mounting member 70. The arm attachment member 70 is fixed to the upper end of a shaft 63, which will be described later, via a bolt. The actuator 1 moves the arm portion 80 up and down in the Z direction (linear motion direction, axial direction of the central axis AX), and rotates the arm portion 80 in a direction around the central axis AX within a plane perpendicular to the Z direction. Since a workpiece (not shown) is mounted on the arm portion 80, the workpiece is transferred to a desired position.

The first motor M1 includes a first stator 10, a first rotor 20, a first motor housing 40, and a first rotation detection section 101.

A first stator holder 11 is arranged inside the first stator 10 in the radial direction. The first stator 10 is fixed to a first stator holder 11. The first rotor 20 is arranged on the outer peripheral side of the first stator 10. The first rotor 20 rotates around the central axis AX. The first rotor 20 includes a first rotor bracket 21 and a first rotor core 22 fixed to the radially inner side of the first rotor bracket 21 and having a permanent magnet. The first rotor bracket 21 is formed into a cylindrical shape centered on the central axis AX. Further, the first rotor bracket 21 has an outer ring retainer 21a that supports the outer ring of the first bearing 31.

The first stator 10 and the first rotor 20 are coaxially arranged around the central axis AX. The first rotor 20 is arranged on the radially outer side of the first stator 10 and the first stator holder 11 and rotates relative to the first stator 10 . In other words, the first rotor 20 is rotatably supported by the first stator 10 and the first stator holder 11 via the first bearing 31 . The first stator holder 11 is fixed to the first motor housing 40 via bolts. The first stator 10 is provided in a cylindrical shape around the central axis AX.

The first motor housing 40 has a cylindrical shape, for example, and accommodates the first motor M1. The upper end of the first motor housing 40 is open, and a first lid member 111 is provided in the opening. The first lid member 111 is fixed to the outer ring retainer 21a of the first rotor bracket 21 via bolts. A through hole is provided in the radial center of the first lid member 111, and the through hole is covered with a spline outer cylinder 61. A recess 112 recessed upward is provided on the lower surface of the first lid member 111 .

A radially extending flange 62 is provided at the lower end of the spline outer cylinder 61. With the flange 62 inserted into the recess 112, the flange 62 is fixed to the first lid member 111 via bolts. Furthermore, an attachment flange 40a that extends outward in the radial direction is provided at the upper end of the first motor housing 40. The mounting flange 40a is placed on the upper surface of the fixed base ST, and can be fixed to the fixed base ST via bolts. A minute gap is formed between the outer peripheral end of the first lid member 111 and the inner peripheral end of the first motor housing 40, so that the first lid member 111 can rotate relative to the first motor housing 40.

The first rotation detection unit 101 is, for example, a resolver. The first rotation detection unit 101 detects the rotation state of the first motor M1. The first rotation detection section 101 is arranged above the first bearing 31.

The second motor M2 is arranged in line with the first motor M1 in the axial direction of the center axis AX. The second motor M2 includes a second stator 10A, a second rotor 20A, a second motor housing 40A, and a second rotation detection section 101A. The first motor M1 and the second motor M2 are cylindrical direct drive motors.

The second rotor 20A is arranged on the outer peripheral side of the second stator 10A. The second rotor 20A rotates around the central axis AX. That is, the central axis of the second rotor 20A is coaxial with the central axis AX of the first rotor 20. The second rotor 20A includes a second rotor bracket 21A and a second rotor core 22A fixed to the radially inner side of the second rotor bracket 21A and having a permanent magnet. The second rotor bracket 21A is formed into a cylindrical shape centered on the central axis AX. The second stator 10A and the second rotor 20A are coaxially arranged around the central axis AX.

The second rotor 20A is arranged on the radially outer side of the second stator 10A and the second stator holder 11A, and rotates relative to the second stator 10A and the second stator holder 11A. In other words, the second rotor 20A is rotatably supported by the second stator 10A and the second stator holder 11A via the second bearing 32. The second stator 10A is fixed to a second stator holder 11A arranged radially inside the second stator 10A. The second stator holder 11A is fixed to the second motor housing 40A via bolts. The second stator 10A is provided in a cylindrical shape around the central axis AX.

Here, the shaft member SF will be explained. The shaft member SF has an upper shaft 63 and a lower threaded shaft 53. The shaft 63 extends from the arm attachment member 70 to the connecting portion 100 along the axial direction of the central axis AX. The connecting portion 100 is provided at a position aligned with the second rotation detecting portion 101A. The shaft 63 has a large diameter portion 631 and a small diameter portion 632. The large diameter portion 631 extends from the arm attachment member 70 to the lower bottom portion 40b of the first motor housing 40.

On the outer periphery of the large diameter portion 631, a plurality of spline groove portions 633 extending in the axial direction of the center axis AX are provided at intervals in the circumferential direction. Although not shown, a spline portion having a plurality of convex portions that can be engaged with the spline groove portion 633 is provided on the inner peripheral side of the spline outer cylinder 61 . As described above, the shaft member SF has a first portion S1 that projects upwardly from the first rotor 20 toward the opposite side of the second rotor 20A, and the first portion S1 has an axial line. A spline groove portion 633 extending along the direction is provided. As the spline groove 633 and the spline part engage with each other via a plurality of balls, the shaft member SF is guided in the axial direction along the spline part, and the shaft member SF rotates together with the first rotor 20. The shaft member SF becomes rotatable in the direction around the central axis. Note that the small diameter portion 632 extends from the lower end of the large diameter portion 631 to the connecting portion 100. In this way, a rolling guide ball spline is applied to the first portion S1.

The screw shaft 53 extends from the connecting portion 100 to the stopper 55. The screw shaft 53 has an upper large diameter portion 531 and a lower small diameter portion 532. A small diameter portion 531a that projects upward is provided at the tip of the large diameter portion 531 of the screw shaft 53 (the upper end in FIG. 1). A male thread is provided on the outer periphery of the narrow diameter portion 531a. A recess 632a is provided at the lower end of the small diameter portion 632 of the shaft 63. A female thread that engages with the male thread of the narrow diameter portion 531a is provided on the inner periphery of the recess 632a. The female thread on the inner periphery of the recess 632a meshes with the male thread on the narrow diameter portion 531a. Thereby, the small diameter portion 632 of the shaft 63 and the large diameter portion 531 of the screw shaft 53 are integrally connected. That is, the shaft 63 and the screw shaft 53 are connected by screw fastening. Note that a male threaded portion 533 is formed on the outer periphery of the large diameter portion 531. That is, the shaft member SF has a second portion S2 that protrudes downward from the second rotor 20A toward the opposite side of the first rotor 20, which is the other side in the axial direction, and the second portion S2 has a male threaded portion 533. provided. Further, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the male thread portion 533. Note that the diameter D1 of the spline groove portion 633 is the larger diameter of the larger diameter and the smaller diameter. The diameter D2 of the male threaded portion 533 is the outer diameter of the outer diameter and the inner diameter (trough diameter).

The second motor housing 40A is formed, for example, in a cylindrical shape and accommodates the second motor M2. The upper end of the second motor housing 40A is open, and the shaft member SF is provided to pass through the opening. An upper bottom portion 40Aa that extends annularly in a direction around the center axis AX is provided on the outer periphery of the opening. The upper base portion 40Aa is in contact with the lower base portion 40b of the first motor housing 40 and is fixed to the lower base portion 40b via a bolt. The lower bottom 40Ab of the second motor housing 40A is also open, and the opening is covered with the nut housing 42 and the stopper cover 44.

The nut housing 42 includes an upper end flange 42a, a cylindrical part 42b formed in a cylindrical shape extending downward from the inner peripheral end of the upper end flange 42a, and a bottom part 42c extending inward from the lower end of the cylindrical part 42b. have The upper end flange 42a is fixed to the lower bottom portion 40Ab of the second motor housing 40A via bolts. The stopper cover 44 is fixed to the bottom 42c of the nut housing 42 via bolts. A through hole is provided in the bottom portion 42c, through which the small diameter portion 532 of the screw shaft 53 is provided.

A stopper 55 is attached to the lower end of the small diameter portion 532 with a nut 56. The stopper 55 is an annular member. The stopper 55 is inserted into the screw shaft 53. An annular buffer member 55a is arranged above the stopper 55 in the Z direction. The buffer member 55a is, for example, an elastic urethane rubber. When the shaft member SF rises, the stopper 55 hits the bottom portion 42c of the nut housing 42 via the buffer member 55a, thereby restricting the rise of the shaft member SF. A nut member 51 and a second connection bracket 45 are housed inside the nut housing 42 .

A female screw portion is provided on the inner peripheral side of the nut member 51 . The female threaded portion engages with the male threaded portion 533 of the second portion S2 of the shaft member SF via a plurality of balls. A second connection bracket 45 is arranged on the radially outer side of the nut member 51. A flange portion 51a that extends outward in the radial direction is formed at the lower end of the nut member 51. The flange portion 51a is fixed to the second connection bracket 45 via bolts. A flange 45a extending radially outward is provided at the upper end of the second connection bracket 45, and the flange 45a is fixed to the first connection bracket 46 via bolts. In this way, a rolling guide ball screw is applied to the second portion S2.

The first connection bracket 46 is fixed to the second rotor bracket 21A via a bolt. In this way, the nut member 51, the second connection bracket 45, the first connection bracket 46, and the second rotor bracket 21A are rotatable as one unit. Specifically, the nut member 51, the second connection bracket 45, the first connection bracket 46, and the second rotor bracket 21A rotate with respect to the second stator 10A and the second stator holder 11A via the second bearing 32. Possibly supported.

The second rotation detection unit 101A is, for example, a resolver. The second rotation detection unit 101A detects the rotation state of the second motor M2. The second rotation detection section 101A is arranged at a position aligned with the coupling section 100 in the axial direction.

Next, the movement of the actuator 1 will be explained.

First, the manner in which the shaft member SF moves up and down (directly moves) will be explained. In this mode, only the second motor M2 operates, and the first motor M1 does not operate.

As shown in FIG. 1, when the second motor M2 operates, the second rotor 20A rotates in a direction around the central axis AX. Specifically, the second rotor 20A rotates around the central axis AX with respect to the second stator 10A and the second stator holder 11A via the second bearing 32. Note that the first rotor 20 does not rotate.

The nut member 51 is integrated with the second rotor 20A. Therefore, the nut member 51 also rotates together with the second rotor 20A in the direction around the central axis AX. Since the female threaded portion of the nut member 51 meshes with the male threaded portion 533 of the second portion S2 of the shaft member SF, rotation of the nut member 51 causes the shaft member SF to move linearly along the axial direction. Specifically, as shown in FIG. 2, the shaft member SF rises along the axial direction. In this state, the shaft member SF also rises, and the stopper 55 hits the bottom portion 42c of the nut housing 42 via the buffer member 55a, thereby restricting the rise of the shaft member SF.

Next, the manner in which the shaft member SF pivots (rotates) will be explained. This aspect includes a first aspect, a second aspect, and a third aspect depending on how the shaft member SF moves in the Z direction.

In the first mode, the first motor M1 is activated and the second motor M2 is not activated. As described above, the spline groove portion 633 and the spline portion mesh with each other. Thereby, the shaft member SF is guided in the axial direction along the spline portion of the spline outer cylinder 61. Further, the shaft member SF rotates together with the first rotor 20 via the spline outer cylinder 61, so that the shaft member SF can rotate in a direction around the center axis AX. Furthermore, since the second motor M2 does not operate, the nut member 51 also does not rotate. Therefore, when the shaft member SF is rotated by the spline outer cylinder 61, the shaft member SF is moved linearly along the axial direction by the nut member 51. As described above, in the first aspect, the shaft member SF rotates integrally with the spline outer cylinder 61 and moves linearly in the Z direction by rotating relative to the stationary nut member 51.

In the second mode, the shaft member SF rotates together with the spline outer cylinder 61 while the nut member 51 is rotated so that the position of the shaft member SF in the Z direction does not change. Therefore, in the second mode, both the first motor M1 and the second motor M2 are operated. That is, the rotation by the first motor M1 is similar to the first aspect, and the shaft member SF rotates together with the first rotor 20 via the spline outer cylinder 61, so that the shaft member SF rotates in the direction around the center axis AX. It becomes possible to rotate. Although the second motor M2 was not operated in the first embodiment, it rotates the nut member 51 in a direction opposite to the direction in which the shaft member SF moves linearly. As described above, in the second aspect, the shaft member SF rotates together with the spline outer cylinder 61 while the position of the shaft member SF in the Z direction does not change.

In the third aspect, the shaft member SF rotates integrally with the spline outer cylinder 61, and by appropriately adjusting the rotation speed of the nut member 51, the speed at which the shaft member SF moves linearly (moving speed in the Z direction) can be adjusted. Make it variable. Therefore, in the third mode, both the first motor M1 and the second motor M2 are operated. That is, the rotation by the first motor M1 is the same as in the first and second embodiments, and the shaft member SF rotates together with the first rotor 20 via the spline outer cylinder 61, so that the shaft member SF rotates around the central axis AX. It becomes possible to rotate around the axis. The second motor M2 sets its rotational speed in accordance with the desired linear motion speed of the shaft member SF. As described above, in the third aspect, the shaft member SF rotates integrally with the spline outer cylinder 61 while appropriately adjusting the moving speed of the shaft member SF in the Z direction.

As described above, the actuator 1 of the present embodiment includes a first motor having a first stator 10 and a first rotor 20 that is rotatable in a direction around the central axis AX with respect to the first stator 10. M1, which is spaced apart from the first motor M1 in the axial direction of the central axis AX, is rotatable with respect to the second stator 10A, and is coaxial with the central axis AX of the first rotor 20. A second motor M2 having a second rotor 20A disposed in A spline groove 633 extending along the axial direction is provided in at least a portion of the first portion S1 that protrudes in one axial direction, and protrudes in the other axial direction from the second rotor 20A toward the opposite side of the first rotor 20. A shaft member SF in which a male threaded portion 533 is provided in at least a portion of the second portion S2 engages with a spline groove 633 of the shaft member SF to guide the shaft member SF in the axial direction along the spline groove 633; A spline outer cylinder 61 that can rotate together with the first rotor 20 to rotate the shaft member SF in the direction around the central axis AX, and a female threaded part that engages with the male threaded part 533 of the shaft member SF, are provided and rotated together with the second rotor 20A. and a nut member 51 capable of moving the shaft member SF in the axial direction of the center axis AX.

In the actuator 1, a spline outer cylinder 61, a first motor M1, a second motor M2, and a nut member 51 are arranged along the axial direction of the central axis AX. Therefore, the radial size is reduced and the footprint is smaller than an actuator having a two-shaft integrated motor in which the second rotor 20A is arranged radially outside the first rotor 20.

Further, the diameter of the spline groove portion 633 in the shaft member SF is larger than the diameter of the male thread portion 533.

The driving force of the first motor M1 rotates the spline outer cylinder 61 in a direction around the center axis AX, and the shaft member SF rotates together with the spline outer cylinder 61. Here, since the diameter of the spline groove portion 633 in the shaft member SF is larger than the diameter of the male thread portion 533, the rigidity of the spline groove portion 633 is higher than that of the male thread portion 533. Therefore, when the shaft member SF is rotated and stopped at a predetermined position in the circumferential direction, it can be stopped at a position closer to the predetermined position. Furthermore, when the shaft member SF is rotated until the shaft member SF is at a predetermined position in the circumferential direction, the time required to position the shaft member SF at the final predetermined position is shortened.

The spline outer cylinder 61 is arranged near the output shaft of the first motor M1, and the nut member 51 is arranged near the output shaft of the second motor M2. Therefore, the spline outer cylinder 61 is less affected by the vibration and inclination of the output shaft of the first motor M1, and the spline outer cylinder 61 can be assembled with high precision. The nut member 51 is less affected by the vibration and inclination of the output shaft of the second motor M2, and the nut member 51 can be assembled with high precision.

Since the first motor M1 and the second motor M2 are separated, the torque of each motor can be set individually.

A spline outer cylinder 61 is provided at one end of the shaft member SF, and a nut member 51 is provided at the other end. Therefore, compared to the case where both the spline outer cylinder 61 and the nut member 51 are provided on one end side of the shaft member SF, the deflection and inclination of the shaft member SF due to the rotation of the spline outer cylinder 61 and the nut member 51 are reduced. .

In each of the first motor M1 and the second motor M2, the motor housing, rotor, and stator are separated, so precision adjustment (centering) is possible when assembling the motor, so the motor can be assembled with high precision. can.

The shaft member SF is divided into a shaft 63 including the first portion S1 and a screw shaft 53 including the second portion S2, and the shaft 63 and the screw shaft 53 are connected by screw fastening.

When the shaft 63 or the threaded shaft 53 is worn out, only the worn member needs to be replaced, so that parts costs can be reduced.

The first motor M1 and the second motor M2 are direct drive motors.

A direct drive motor directly transmits the generated driving force to an object without using a speed reduction mechanism. That is, the shaft member SF can be rotated by directly rotating the spline outer cylinder 61 with the driving force of the first motor M1. Further, by directly rotating the nut member 51 with the driving force of the second motor M2, the shaft member SF can be moved in a linear manner.

An arm attachment member 70 is fixed to the end of the first portion S1 of the shaft member SF, and the arm attachment member 70 supports an arm portion 80 to which a workpiece is attached.

Since the first portion S1 of the shaft member SF is provided with the spline outer cylinder 61 that engages with the spline groove portion 633, vibration and inclination are reduced when the shaft member SF rotates. Therefore, the vibration and inclination when the arm attachment member 70 and the arm portion 80 rotate are also reduced, so that the workpiece can be stably rotated and raised and lowered.

[Second embodiment]
Next, an actuator 1A according to a second embodiment will be explained. Components that are the same as those in the first embodiment are given the same reference numerals and descriptions thereof will be omitted. Hereinafter, the differences from the first embodiment will be mainly explained.

FIG. 3 is a sectional view of the actuator of the second embodiment, showing a state in which the stroke of the shaft member is at the lower limit. FIG. 4 is a cross-sectional view of the actuator of the second embodiment, showing a state in which the stroke of the shaft member is at the upper limit.

The second embodiment is different from the first embodiment in the structure of the shaft member SF. That is, in the first embodiment, the shaft member SF is divided into an upper shaft 63 and a lower threaded shaft 53. The large diameter portion 531 of the screw shaft 53 and the small diameter portion 632 of the shaft 63 are integrally connected by screw fastening.

However, the shaft member SF according to the second embodiment is formed by integrally connecting the upper shaft 63 and the lower threaded shaft 53. For example, the shaft member SF having the shapes of the shaft 63 and the screw shaft 53 is formed by cutting the outer peripheral portion of one cylindrical metal member. Further, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the male thread portion 533. Here, the diameter D1 of the spline groove portion 633 is the larger diameter of the larger diameter and the smaller diameter. The diameter D2 of the male threaded portion 533 is the outer diameter of the outer diameter and the inner diameter (trough diameter).

Note that the lifting and lowering and turning of the shaft member SF are the same as in the first embodiment. Further, when the second motor M2 operates at the lower limit position of the shaft member SF shown in FIG. 3, the nut member 51 also rotates together with the second rotor 20A, and as shown in FIG. Rise.

As explained above, in the actuator 1A of this embodiment, the shaft member SF is formed by integrally connecting the upper shaft 63 and the lower threaded shaft 53. Therefore, the rigidity of the shaft member SF becomes higher than when the shaft 63 and the threaded shaft 53 are connected separately.

[Third embodiment]
Next, an actuator 1B according to a third embodiment will be described. Components that are the same as those in the first embodiment and the second embodiment are given the same reference numerals, and description thereof will be omitted. Hereinafter, the differences from the first embodiment will be mainly explained.
FIG. 5 is a sectional view of the actuator of the third embodiment. FIG. 6 is an enlarged cross-sectional view of the main part of FIG. FIG. 7 is an enlarged cross-sectional view of another essential part of FIG. FIG. 8 is a cross-sectional view of the actuator of the third embodiment, showing a state in which the stroke of the shaft member is at the upper limit.

In the present embodiment, a portion above the first motor M1 (detailed in FIG. 6) and a portion below the nut member 51 (detailed in FIG. 7) are mainly used in the first embodiment. and is different from the second embodiment.
The arm attachment member 70A is connected to the tip (upper end) of the shaft 63. The arm attachment member 70A includes a connecting portion 71, a cylindrical portion 72, and a lid portion 73. The connecting portion 71 is connected to the reduced diameter portion 63a of the shaft 63.

As shown in FIG. 6, the cylindrical portion 72 is formed in a cylindrical shape and is provided in a state extending downward from the connecting portion 71. As shown in FIG. The cylindrical part 72 is arranged outside the second cylindrical part 432 of the spline outer cylinder housing 43 and accommodates the upper part 432a of the second cylindrical part 432. A recess 72a is provided at the lower end of the cylindrical portion 72. The recessed portion 72a is formed by enlarging the lower end of the inner peripheral surface. A seal portion 77 is arranged in the recess 72a.

The seal portion 77 seals a gap formed between the cylindrical portion 72 and the upper portion 432a of the second cylindrical portion 432 of the spline outer cylinder housing 43. Examples of the seal portion 77 include a structure in which a U-shaped or U-shaped member is formed into a ring shape when viewed in cross section. The seal portion 77 is formed using, for example, an elastically deformable material. The seal portion 77 protects the shaft 63 from the outside. Note that a protrusion 72b that protrudes inward is formed at the lower end of the recess 72a. This projection 72b prevents the seal portion 77 from falling.

Further, a cylindrical gap is formed between the cylindrical portion 72 and the upper portion 432a of the second cylindrical portion 432. This gap forms a labyrinth structure between the shaft 63 and the outside, thereby improving dustproofness and waterproofness.

The lid part 73 is attached to the lid part attachment surface 71d of the connecting part 71 with bolts. The lid portion 73 protects the reduced diameter portion 63a of the shaft 63 from the outside.

The spline outer cylinder housing 43 has a first cylindrical part 431 and a second cylindrical part 432. Further, a second lid member 111A is fixed to the upper end of the first rotor bracket 21 via a bolt. A flange 62A of a spline outer cylinder 61A is fixed to the upper end of the second lid member 111A via a bolt.

The first cylindrical portion 431 includes a first cylindrical portion 431b disposed above in the vertical direction, a stepped portion 431d disposed below the first cylindrical portion 431b, and a stepped portion 431d disposed below the stepped portion 431d. It has a second cylindrical portion 431e.

The first cylindrical portion 431b is provided with a receiving portion 431a extending radially inward in an annular shape along the circumferential direction. A downwardly recessed portion is provided on the upper surface of the receiving portion 431a, and the O-ring 74 is accommodated in the recessed portion. With the lower end surface of the second cylindrical portion 432 pressing against the O-ring 74, the lower end portion of the second cylindrical portion 432 is fixed to the receiving portion 431a of the first cylindrical portion 431 via a bolt. A recess is formed in the side surface of the lower end 431c of the second cylindrical portion 431e, and an O-ring 75 is accommodated in the recess.

The inner peripheral surface of the upper end of the first motor housing 40 presses the O-ring 75. In this state, the lower end of the first cylindrical portion 431 is fixed to the upper end of the first motor housing 40 via bolts. Furthermore, a recessed portion recessed radially inward is provided on the outer peripheral surface of the upper end portion of the first motor housing 40, and an O-ring 76 is accommodated in the recessed portion. With the inner peripheral surface of the fixed base ST pressing the O-ring 76, the mounting flange 40a of the first motor housing 40 is fixed to the upper surface of the fixed base ST via bolts.

As shown in FIG. 6, the third bearing 33 is held between the second cylindrical portion 431e and the connection bracket 34 in the first cylindrical portion 431. As shown in FIG. The connection bracket 34 is fixed to the flange 62A of the spline outer cylinder 61A. Therefore, the third bearing 33 rotatably supports the spline outer cylinder 61 and the connection bracket 34. The third bearing 33 is, for example, a rolling bearing. The third bearing 33 is supported by the step portion 431d via the wave washer 39a and the pressing member 39b. The third bearing 33 is pressed against the connection bracket 34 by a wave washer 39a and a pressing member 39b. Further, the third bearing 33 is supported in the radial direction by the first cylindrical portion 431, the first motor housing 40, and the fixed base ST.

Here, the shaft member SF will be explained. The shaft member SF has an upper shaft 63 and a lower threaded shaft 53. The shaft 63 extends from the arm attachment member 70A to the connecting portion 100 along the axial direction of the central axis AX. The connecting portion 100 is provided at a position aligned with the second rotation detecting portion 101A in the axial direction. The shaft 63 is constructed by integrating a reduced diameter portion 63a, a large diameter portion 63b, and a small diameter portion 63c. The large diameter portion 63b includes a first large diameter portion 63b1 disposed below the reduced diameter portion 63a, a second large diameter portion 63b2 accommodated inside the second cylindrical portion 432, and a spline outer cylinder 61A. It has a third large diameter portion 63b3 extending from the upper end to the lower bottom portion 40b of the first motor housing 40. A plurality of spline groove portions 633 extending in the axial direction of the central axis AX are provided on the outer periphery of the third large diameter portion 63b3 at intervals in the circumferential direction. Note that the portion where the spline groove portion 633 is provided and protrudes upward from the upper end of the first rotor 20 is the first portion S1.

The screw shaft 53 extends from the connecting portion 100 to the stopper 55. The screw shaft 53 has an upper large diameter portion 531 and a lower small diameter portion 532. The upper end of the large diameter portion 531 of the screw shaft 53 is provided with a small diameter portion 531a that projects upward. A male thread is provided on the outer periphery of the narrow diameter portion 531a. A recess 632a is provided at the lower end of the small diameter portion 632 of the shaft 63. A female thread that engages with the male thread of the narrow diameter portion 531a is provided on the inner periphery of the recess 632a. The female thread on the inner periphery of the recess 632a meshes with the male thread on the narrow diameter portion 531a. Thereby, the small diameter portion 632 of the shaft 63 and the large diameter portion 531 of the screw shaft 53 are integrally connected. That is, the shaft 63 and the screw shaft 53 are connected by screw fastening. Note that a male threaded portion 533 is formed on the outer periphery of the large diameter portion 531. That is, the shaft member SF has a second portion S2 that protrudes downward from the second rotor 20A toward the opposite direction of the first rotor 20, which is the other axial direction, and the second portion S2 has a male threaded portion 533. provided. Note that no male threaded portion is provided on the outer periphery of the small diameter portion 532. Further, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the male thread portion 533. Note that the diameter D1 of the spline groove portion 633 is the larger diameter of the larger diameter and the smaller diameter. The diameter D2 of the male threaded portion 533 is the outer diameter of the outer diameter and the inner diameter (trough diameter).

As shown in FIG. 7, the clamp mechanism 130 includes a small diameter portion 532 of the screw shaft 53, a collet 132, and a cylinder 134. The collet 132 includes a radially deformable grip portion 132A and a substantially cylindrical flange portion 132B. Four slots are formed in the grip portion 132A in the Z direction. The sectional view shown in FIG. 7 shows a cross section taken along the slit. The slots are formed at positions that differ by 90 degrees in the circumferential direction. Thereby, the grip portion 132A can be elastically deformed in the radial direction. Note that the number, shape, and position of the slots are not particularly limited. The slots may be formed so that the grip portion 132A can be elastically deformed in the radial direction.

A small diameter portion 532 of the screw shaft 53 is inserted into the collet 132 . The collet 132 includes a first tapered surface 132a, a second tapered surface 132b, a recess 132c, and an inner peripheral surface 132d. The first tapered surface 132a is the outer peripheral surface of the grip portion 132A. The first tapered surface 132a is an inclined surface whose outer diameter decreases toward the lower side in the Z direction. That is, the first tapered surface 132a has a substantially conical shape.

The second tapered surface 132b is an upper outer circumferential surface of the flange portion 132B in the Z direction. The second tapered surface 132b is an inclined surface whose outer diameter becomes smaller toward the upper side in the Z direction. In other words, the second tapered surface 132b has a substantially conical shape. The recessed portion 132c is a groove formed in the outer peripheral surface of the flange portion 132B. The recess 132c is formed between the first tapered surface 132a and the second tapered surface 132b in the Z direction. The inner circumferential surface 132d is a surface facing the clamped portion 53b of the screw shaft 53. The collet 132 is arranged such that the inner peripheral surface 132d faces the clamped portion 53b of the screw shaft 53 even when the screw shaft 53 moves to the maximum extent in the axial direction.

The cylinder 134 includes a piston 136, a cylinder tube 138, a first seal member 160, and a second seal member 162. The cylinder 134 also includes a gas supply section 163, a fixing member 144, a stopper section 146, a screw shaft housing 150, and a spring 156.

The small diameter portion 532 of the screw shaft 53 is inserted into the piston 136 . The piston 136 includes an inclined surface 136a, a first outer surface 136b, a second outer surface 136c, a groove 136d, a lower surface 136e, a recess 136f, and an upper surface 136g.

The inclined surface 136a is the inner peripheral surface of the piston 136 on the upper side in the Z direction. The inclined surface 136a is inclined so that the diameter becomes larger toward the upper side in the Z direction. The inclined surface 136a overlaps the first tapered surface 132a in the Z direction. With this configuration, the inclined surface 136a can come into contact with the first tapered surface 132a when the piston 136 moves upward in the Z direction. When the inclined surface 136a comes into contact with the first tapered surface 132a, it can press the first tapered surface 132a inward in the radial direction. That is, the inclined surface 136a is a chuck part that can press the grip part 132A inward in the radial direction. The inclined surface 136a faces the first tapered surface 132a. That is, the inclined surface 136a and the first tapered surface 132a have substantially the same inclination. The inclined surface 136a is arranged so as to overlap the first tapered surface 132a in the radial direction. Thereby, the axial dimension of the space occupied by the piston 136 and the collet 132 can be reduced.

The first outer surface 136b and the second outer surface 136c are outer surfaces of the piston 136. The first outer surface 136b is located above the second outer surface 136c in the Z direction. The second outer surface 136c has a larger diameter than the first outer surface 136b. The first outer surface 136b and the second outer surface 136c are arranged to overlap with the first tapered surface 132a in the radial direction. The groove portion 136d is a square groove formed in the first outer surface 136b. The groove portion 136d is formed along the circumferential direction of the first outer surface 136b. The lower surface 136e is the lower surface of the piston 136 in the Z direction. A recessed portion 136f recessed upward in the Z direction is formed in the lower surface 136e. The upper surface 136g is the upper surface of the piston 136 in the Z direction.

The cylinder tube 138 is a substantially cylindrical member that accommodates the piston 136. It includes a cylindrical portion 138a, an outer flange portion 138b, an inner flange portion 138c, a groove portion 138d, a first inner surface 138e, a second inner surface 138f, and a gas supply path 138g. The cylindrical portion 138a is a cylindrical member. An outer flange portion 138b and an inner flange portion 138c are connected to the upper end of the cylindrical portion 138a in the Z direction. The outer diameter side flange portion 138b is a flange surface formed in an annular shape. The outer diameter side flange portion 138b is fixed to the lower end of the cylindrical portion 42b by a fixing member 140. The inner diameter side flange part 138c is formed in an annular shape and is arranged radially inward than the outer diameter side flange part 138b. A stepped surface 142 is formed on the inner diameter side flange portion 138c. The step surface 142 is formed at the upper end in the Z direction of the inner diameter side flange portion 138c. The stepped surface 142 has an annular shape when viewed from above in the Z direction.

The first inner surface 138e is a radially inner side surface of the inner diameter side flange portion 138c. The first inner surface 138e faces the first outer surface 136b. The second inner surface 138f is a radially inner side surface of the cylindrical portion 138a. The diameter of the second inner surface 138f is larger than the diameter of the first inner surface 138e. The second inner surface 138f faces the second outer surface 136c. The first inner surface 138e and the second inner surface 138f are arranged to overlap with the first tapered surface 132a in the radial direction. The groove portion 138d is a square groove formed in the second inner surface 138f. The groove portion 138d is formed along the circumferential direction of the second inner surface 138f.

The gas supply path 138g is an opening that penetrates from the outside of the cylinder tube 138 to the inside of the cylinder tube 138. A gas supply pipe 158 is connected to the gas supply path 138g. The gas supply path 138g and the gas supply pipe 158 are fixed to each other with screws, for example, with a seal tape interposed therebetween.

The first seal member 160 is an O-ring. The first seal member 160 is arranged in the groove portion 136d. The first seal member 160 fills the gap between the first outer surface 136b and the first inner surface 138e. According to this, the gap between the first outer surface 136b and the first inner surface 138e is sealed.

The second seal member 162 is an O-ring. The second seal member 162 is arranged in the groove 138d. The second seal member 162 fills the gap between the second outer surface 136c and the second inner surface 138f. According to this, the gap between the second outer surface 136c and the second inner surface 138f is sealed. With such a configuration, the gas supply pipe 158, the gas supply path 138g, the first outer surface 136b, the second outer surface 136c, the first inner surface 138e, the second inner surface 138f, the first seal member 160, and the second seal member A pressure chamber 139 surrounded by 162 is formed.

The gas supply unit 163 is a compressor that supplies compressed air. Gas supply section 163 is connected to gas supply piping 158. Note that the gas supplied by the gas supply section 163 is not limited to compressed air. The gas supply unit 163 may supply compressed nitrogen, for example.

The fixing member 144 is an annular plate member. The fixing member 144 is arranged such that its radially outer lower surface contacts the step surface 142. Furthermore, the radially inner end of the fixing member 144 is inserted into the recess 132c.

The stopper portion 146 is an annular member. The small diameter portion 52B of the screw shaft 53 is inserted into the stopper portion 146. The stopper portion 146 includes an inclined surface 146a facing the second tapered surface 132b. Thereby, the stopper portion 146 can restrict the movement of the collet 132 upward in the Z direction. Further, the stopper portion 146 is fixed to the inner diameter side flange portion 138c by the fixing member 148 with the fixing member 144 sandwiched between the step surface 142. Therefore, the stopper portion 146 fixes the position of the fixing member 144 in the Z direction. The inner end of the fixing member 144 is inserted into the recess 132c. According to this, the fixing member 144 can restrict movement of the collet 132 downward in the Z direction. With such a configuration, the position of the collet 132 in the Z direction is determined.

The screw shaft housing 150 is fixed to the fixed base ST via the cylinder tube 138, the nut housing 42, the motor housing 41, and the spline outer cylinder housing 43. The screw shaft housing 150 includes a flange portion 150a, a flange surface 150b, a cylindrical portion 150c, a recessed portion 150d, and a lid member 150e. The flange portion 150a is formed in an annular shape and is fixed to the lower end of the cylindrical portion 138a by a fixing member 152. The flange surface 150b is the upper surface of the flange portion 150a in the Z direction.

The flange surface 150b faces the lower surface 136e. The cylindrical portion 150c extends downward from the inner periphery of the flange portion 150a. As shown in FIG. 5, the cylindrical portion 150c accommodates the lower end of the screw shaft 53. The recess 150d is recessed downward in the Z direction from the flange surface 150b. The lid member 150e is a member that closes the lower side of the cylindrical portion 150c in the Z direction. The lid member 150e is fixed to the lower end surface of the cylindrical portion 150c in the Z direction with bolts. This can prevent foreign matter from entering the screw shaft housing 150 from the lower side in the Z direction.

Spring 156 is a compression coil spring. One end of the spring 156 contacts the bottom surface of the recess 136f. The other end of the spring 156 contacts the bottom surface of the recess 150d. Therefore, the spring 156 is compressed by the bottom surface of the recess 136f and the bottom surface of the recess 150d. Since the screw shaft housing 150 is fixed to the fixed base ST, the bottom surface of the recess 150d does not move downward in the Z-axis direction. Therefore, the spring 156 presses the piston 136 upward in the Z direction. Although the spring 156 is a compression coil spring, it is not limited thereto. The spring 156 may be any elastic member that biases the piston 136 in a direction in which the piston 136 approaches the grip portion 132A. Spring 156 may be, for example, a square spring and a conical spring. Further, a plurality of springs 156 may be arranged.

A stopper 55 is attached to the lower end of the screw shaft 53 with a nut 56. The stopper 55 is an annular member. The stopper 55 is inserted into the screw shaft 53. An annular buffer member 55a is arranged above the stopper 55 in the Z direction. The buffer member 55a is, for example, an elastic urethane rubber. The outer diameter r2 of the buffer member 55a and the stopper 55 is larger than the inner diameter r1 of the flange portion 150a. Therefore, when the screw shaft 53 rises by a predetermined length, the stopper 55 comes into contact with the flange portion 150a via the buffer member 55a. Thereby, the stopper 55 can prevent the screw shaft 53 from rising beyond a predetermined length.

Note that the raising/lowering and turning of the shaft member SF is the same as in the first and second embodiments. Furthermore, when the second motor M2 operates at the lower limit position of the shaft member SF shown in FIG. 5, the nut member 51 also rotates together with the second rotor 20A, and as shown in FIG. Rise.

As described above, the actuator 1B of the present embodiment includes a collet 132 through which the second portion S2 of the shaft member SF passes, a piston 136 through which the second portion of the shaft member SF passes, and a cylinder tube 138 that accommodates the piston 136. and a cylinder 134 having an elastic member that biases a piston 136. The piston 136 has an inclined surface 136a (chuck part) that presses the collet 132 against the shaft member SF by contacting the outer peripheral surface of the collet 132 with an elastic member. When supplied, it separates from the shaft member SF.

According to this configuration, the elastic member can urge the chuck portion to come into contact with the outer circumferential surface of the collet 132. The chuck section can then press the collet 132 against the shaft member SF to clamp the shaft member. Further, since the chuck portion is configured to be in contact with the outer circumferential surface of the collet 132, it overlaps with the outer circumferential surface in the radial direction. With such a configuration, the axial dimension of the clamp mechanism 130 can be reduced. Further, by supplying gas or liquid to the inside of the cylinder tube 138, the shaft member SF can be unclamped. Further, even when the power is cut off, the shaft member SF can be held by the clamp mechanism 130.

The outer circumferential surface is a tapered surface whose diameter decreases as it approaches the chuck portion, and the chuck portion is a first tapered surface 132a (slanted surface) facing the outer circumferential surface.

According to this configuration, the first tapered surface 132a can make surface contact with the tapered surface when no gas or liquid is supplied to the inside of the cylinder tube 138. Thereby, the frictional force generated between the collet 132 and the chuck part can be increased compared to the case where the outer circumferential surface of the collet 132 and the chuck part are in line contact or point contact. Therefore, when the collet clamps the shaft member SF, it is possible to suppress the outer peripheral surface of the collet 132 and the chuck portion from slipping.

The radially outer side of the spline outer cylinder 61A is supported by the spline outer cylinder housing 43 via the third bearing 33 (rolling bearing).

For example, when the workpiece is supported by the arm section 80 and the center of gravity of the load of the arm section 80 and the workpiece does not coincide with the center axis AX, or when receiving the rotational moment of the arm section 80 and the workpiece, the shaft member SF is aligned with the center axis AX. There is a possibility that a force may be applied in a direction that tilts the object. On the other hand, since the third bearing 33 is supported in the radial direction by the first cylindrical portion 431, the first motor housing 40, and the fixed base ST via the wave washer 39a and the holding member 39b, the center axis AX is Displacement or vibration of the spline outer cylinder 61A in the radial direction perpendicular to the axial direction is suppressed.

A cylindrical gap is formed between the first portion S1 and a cylindrical portion provided on the arm attachment member 70A fixed to the tip of the first portion S1 and covering the outer periphery of the first portion S1.

Since a labyrinth structure is formed between the first portion S1 and the outside of the cylindrical gap due to the cylindrical gap, the dustproof and waterproof properties of the inside of the arm attachment member 70A are improved.

[Fourth embodiment]
Next, an actuator 1C according to a fourth embodiment will be explained. Components that are the same as those in the first embodiment, the second embodiment, and the third embodiment are given the same reference numerals, and description thereof will be omitted. Hereinafter, the differences from the third embodiment will be mainly explained.

FIG. 9 is a sectional view of the actuator of the fourth embodiment, showing a state in which the stroke of the shaft member is at the lower limit. FIG. 10 is a sectional view of the actuator of the fourth embodiment, showing a state in which the stroke of the shaft member is at the upper limit.

The fourth embodiment is different from the third embodiment in the structure of the shaft member SF.

That is, in the third embodiment, the shaft member SF is divided into an upper shaft 63 and a lower threaded shaft 53. The large diameter portion 531 of the screw shaft 53 and the small diameter portion 632 of the shaft 63 are integrally connected by screw fastening.

However, the shaft member SF according to the fourth embodiment is formed by integrally connecting the upper shaft 63 and the lower threaded shaft 53. For example, the shaft member SF having the shapes of the shaft 63 and the screw shaft 53 is formed by cutting the outer peripheral portion of one cylindrical metal member. Further, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the male thread portion 533. Here, the diameter D1 of the spline groove portion 633 is the larger diameter of the larger diameter and the smaller diameter. The diameter D2 of the male threaded portion 533 is the outer diameter of the outer diameter and the inner diameter (trough diameter).

Note that the lifting and lowering and turning of the shaft member SF are the same as in the first embodiment, the second embodiment, and the third embodiment. Furthermore, when the second motor M2 operates at the lower limit position of the shaft member SF shown in FIG. Rise.

As explained above, in the actuator 1C of this embodiment, the shaft member SF is formed by integrally connecting the upper shaft 63 and the lower threaded shaft 53. Therefore, the rigidity of the shaft member SF becomes higher than when the shaft 63 and the threaded shaft 53 are connected separately.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to those described in the above embodiments. For example, in the shaft member SF, the shaft 63 and the threaded shaft 53 are connected by screw fastening, but the end of the shaft 63 may be press-fitted into the end of the threaded shaft 53 for connection. Alternatively, the shaft 63 and the screw shaft 53 may be connected using an adhesive.

1, 1A, 1B, 1C Actuator 10 First stator 10A Second stator 130 Clamp mechanism 132 Collet 134 Cylinder 136 Piston 138 Cylinder tube 20 First rotor 20A Second rotor 33 Third bearing (rolling bearing)
43 Housing for spline outer cylinder 51 Nut member 53 Screw shaft 533 Male thread part 61 Spline outer cylinder 61A Spline outer cylinder 63 Shaft 633 Spline groove 70 Arm mounting member 70A Arm mounting member 72 Cylindrical part 80 Arm part AX Central axis S1 First part S2 Second portion SF Shaft member M1 First motor M2 Second motor

Claims (8)

a first motor having a first stator and a first rotor rotatable in a direction around a central axis with respect to the first stator;
The rotor is disposed apart from the first motor in the axial direction of the central shaft, is rotatable relative to a second stator, and is coaxial with the central axis of the first rotor. a second motor having a second rotor;
At least a portion of a first portion that passes through the first rotor and the second rotor in the axial direction and projects from the first rotor in one direction in the axial direction toward the opposite side of the second rotor. A shaft provided with a spline groove extending along the axial direction, and a male screw portion provided in at least a portion of a second portion that protrudes from the second rotor toward the opposite side of the first rotor in the other axial direction. parts and
Engages with the spline groove of the shaft member to guide the shaft member in the axial direction along the spline groove, and rotates together with the first rotor to move the shaft member in the axial direction of the central axis. A rotatable spline outer cylinder,
a nut member that is provided with a female threaded portion that engages with the male threaded portion of the shaft member and that can rotate together with the second rotor to move the shaft member in the axial direction of the central shaft ;
The first diameter of the spline groove in the shaft member is the larger diameter of the larger diameter and the smaller diameter, and the second diameter of the male threaded part is the outer diameter of the outer diameter and the inner diameter,
The first diameter is larger than the second diameter.
actuator. The actuator according to claim 1 , wherein the shaft member is divided into a shaft including the first portion and a screw shaft including the second portion, and the shaft and the screw shaft are connected by screw fastening. The actuator according to claim 1 or 2 , wherein the first motor and the second motor are direct drive motors. The actuator according to any one of claims 1 to 3 , wherein an arm attachment member is fixed to an end of the first portion of the shaft member, and the arm attachment member supports an arm portion to which a workpiece is attached. a collet through which the second portion of the shaft member passes;
a cylinder including a piston through which the second portion of the shaft member passes, a cylinder tube that accommodates the piston, and an elastic member that biases the piston;
Equipped with a clamping mechanism including
The piston has a chuck portion that presses the collet against the shaft member by contacting the outer peripheral surface of the collet with the elastic member,
The actuator according to any one of claims 1 to 4 , wherein the collet separates from the shaft member when gas or liquid is supplied to the inside of the cylinder tube. The outer circumferential surface is a tapered surface whose diameter decreases as it approaches the chuck portion,
The actuator according to claim 5 , wherein the chuck portion is an inclined surface facing the outer peripheral surface. The actuator according to any one of claims 1 to 6 , wherein the radially outer side of the spline outer cylinder is supported by a spline outer cylinder housing via a rolling bearing. A cylindrical gap is formed between the first portion and a cylindrical portion provided on an arm attachment member fixed to a tip of the first portion and covering an outer periphery of the first portion. 7. The actuator according to any one of 7 .

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