TWI825192B - actuator - Google Patents

Abstract

An actuator is provided with: a first motor having a first stator and a first rotor; and a second motor being arranged separately from the first motor in the axial direction of a central axis and having a second the stator and the second rotor; and a shaft member that penetrates the first rotor and the second rotor in the axial direction, and is provided with a spline groove portion at a first portion protruding from the first rotor toward the opposite side of the second rotor, and from The second portion of the second rotor protruding toward the opposite side of the first rotor is provided with an external thread portion; and a spline outer cylinder that is engaged with the spline groove portion of the shaft member and guides the shaft member toward the axial direction along the spline groove portion. lead, and rotate together with the first rotor to rotate the shaft member in the axial direction about the central axis; and a nut member provided with an internal thread portion that engages with the external thread portion of the shaft member, and with The second rotor rotates together to move the shaft member toward the axial direction of the central shaft.

Description

actuator

The present invention relates to an actuator.

An actuator that performs rotational motion and linear motion is known (see Patent Document 1). The actuator described in Patent Document 1 has a ball screw and a ball spline, and uses a shaft member that connects the screw shaft of the ball screw and the shaft of the ball spline. In this structure, the nut of the ball screw rotates to cause the shaft member to move linearly, and the spline outer cylinder of the ball spline rotates to cause the shaft member to rotate.

Furthermore, the actuator of Patent Document 1 is equipped with a two-axis integrated motor. The two-shaft integrated motor has a first rotor and a second rotor arranged radially outside the first rotor. A nut is fixed to the first rotor, and the rotation of the nut causes the shaft member to move linearly. The shaft member is rotated by the second rotor. [Prior technical literature] [Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2013-230076

[Problem to be solved by the invention]

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

The present invention was developed in view of the above-mentioned problems, and its purpose is to provide an actuator that can reduce the coverage area and achieve space saving. [Means to solve the problem]

The actuator of the present invention is provided with: a first motor having a first stator and a first rotor. The first rotor is oriented in the circumferential direction with the central axis as the center relative to the first stator. and a second motor, which is arranged separately from the first motor in the axial direction of the central axis, and has a second stator and a second rotor, and the second rotor is capable of rotating relative to the second stator. The rotor rotates and is arranged coaxially with the central axis of the first rotor; and a shaft member that penetrates the first rotor and the second rotor in the axial direction in the opposite direction from the first rotor to the second rotor. At least a part of the first part protruding in one side of the aforementioned axial direction is provided with a spline groove portion extending along the aforementioned axial direction, and protruding from the aforementioned side on the opposite side from the aforementioned second rotor toward the aforementioned first rotor. At least a part of the second part on the other side in the axial direction is provided with an external thread part; and a spline outer cylinder that is engaged with the spline groove part of the shaft member and moves the shaft member toward the spline groove part along the spline groove part. The shaft member is guided in the axial direction and rotates together with the first rotor to rotate the shaft member in the axial direction about the central axis; and a nut member provided with the external thread portion connected to the shaft member. The meshed internal thread portion rotates together with the second rotor to move the shaft member toward the axial direction of the central shaft.

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 with an actuator having a biaxial integrated motor in which the second rotor is arranged radially outside the first rotor, the radial size can be reduced, the coverage area can be made smaller, and space can be saved.

In addition, since the first motor and the second motor are separated, the torque of the respective motors can be set individually. Furthermore, a spline outer cylinder is provided on one end side of the shaft member, and a nut member is provided on the other end side. Therefore, compared with the case where both the spline outer cylinder and the nut member are provided on one end side of the shaft member, the vibration or inclination of the shaft member caused by the rotation of the spline outer cylinder and the nut member becomes more severe. Small.

As a preferred form, the diameter of the spline groove portion in the shaft member is larger than the diameter of the external thread portion.

The spline outer cylinder is rotated in the axial direction about the central axis by the driving force of the first motor, and the shaft member rotates together with the spline outer cylinder. Here, since the diameter of the spline groove part in the shaft member is larger than the diameter of the external thread part, the rigidity of the spline groove part becomes higher than that of the external thread part. 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. Furthermore, when the rotation operation of the shaft member is performed before the shaft member reaches the predetermined position in the circumferential direction, the time required to reach the final predetermined position can be shortened.

As a preferred form, the shaft member is divided into a shaft including the first part and a screw shaft including the second part, and the shaft and the screw shaft are connected through a connecting member.

Accordingly, when the shaft or the screw shaft is worn or the like, only the worn components of the shaft or the screw shaft can be replaced, thereby reducing the cost of parts.

As a preferred form, the first motor and the second motor are direct drive motors.

Direct drive motors transmit the generated driving force directly to the object without passing through a reduction mechanism. That is, the spline outer cylinder is directly rotated by the driving force of the first motor, whereby the shaft member can be rotated. In addition, the nut member is directly rotated by the driving force of the second motor, thereby allowing the shaft member to move linearly.

As a preferred form, an arm mounting member is fixed to the end of the first part of the shaft member, and the arm mounting member supports an arm portion on which a workpiece (work) can be mounted.

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

As a preferred form, a clamping (chuck) mechanism is provided, and the clamping mechanism includes: a collet, which is used for the second part of the aforementioned shaft member to pass through; and a cylinder (cylinder), which has A piston for the second part of the shaft member to pass through, a cylinder tube for accommodating the piston, and an elastic member for urging the piston; the piston has a clamping part, and the clamping part is The elastic member comes into contact with the outer peripheral surface of the collet, thereby pressing the collet against the shaft member; the collet is separated from the shaft member when gas or liquid is supplied to the inside of the cylinder tube. .

According to this configuration, the elastic member can urge the clamping portion in such a manner that the clamping portion comes into contact with the outer peripheral surface of the collet. Then, the clamping part presses the collet against the shaft member to clamp the shaft member. In addition, since the clamping portion is configured to be in contact with the outer peripheral surface of the collet, it overlaps with the outer peripheral surface in the radial direction. With such a structure, the size of the clamping mechanism in the axial direction can be reduced. Furthermore, by supplying gas or liquid to the inside of the cylinder tube, the shaft member can be loosened. Furthermore, even when the power supply is cut off, the shaft member can still be held by the clamping mechanism.

As a preferred form, the outer peripheral surface is a tapered surface whose diameter becomes smaller as it approaches the clamping portion; and the clamping portion is an inclined surface facing the outer peripheral surface.

According to this configuration, the inclined surface can come into surface contact with the tapered surface without gas or liquid being supplied to the inside of the cylinder tube. Thereby, compared with the case where the outer peripheral surface of the collet and the clamping part are in line contact or point contact, the friction force generated between the collet and the clamping part can be increased. Therefore, when the collet has clamped the shaft member, the outer peripheral surface of the collet and the clamping portion can be suppressed from sliding.

As a preferred form, the radial outer side of the spline outer cylinder is supported by the spline outer cylinder shell through a rolling bearing.

When the shaft member supporting the workpiece receives a rotational moment from the workpiece, it is possible that the shaft member receives a force in a direction in which the shaft member is inclined relative to the central axis. Here, the radially outer side of the spline outer cylinder is supported by the spline outer cylinder housing through the bearing. Therefore, the radial displacement or vibration of the spline outer cylinder perpendicular to the axial direction of the central shaft can be suppressed.

As a preferred form, a cylindrical gap is formed between the cylindrical portion and the first portion, and the cylindrical portion is provided on an arm mounting member fixed to the front end of the first portion and covers the outer periphery of the first portion.

Since the cylindrical gap forms a labyrinth structure between the first portion and the outside of the cylindrical gap, the dustproof and waterproof properties of the inside of the arm mounting member can be improved. [Effects of the invention]

According to the present invention, it is possible to provide an actuator that can reduce the coverage area and save space.

Modes (embodiments) for implementing the invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. In addition, the structural elements described below include those that can be easily imagined by a person with ordinary knowledge in the technical field to which the invention belongs and are substantially the same. Furthermore, the structural elements described below can be combined appropriately.

[First Embodiment] Fig. 1 is a cross-sectional view of the actuator according to the first embodiment. The cross section of FIG. 1 is a cross section of a plane including the central axis AX of the first rotor and the second rotor described later. FIG. 2 is a cross-sectional view of the actuator according to the first embodiment, showing a state in which the stroke of the shaft member is at the upper limit.

As shown in Figure 1, the actuator 1 is used, for example, as a pick and place device. The actuator 1 includes an arm 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 and the direction from the first motor M1 toward the arm 80 will be referred to as "upper", and the direction from the arm 80 toward the first motor M1 will be referred to as "downward". In addition, the axis direction of the central axis AX of the arm portion 80 is the same as the Z direction.

The arm 80 is, for example, a cantilever-type arm having only a single arm. In the actuator 1, for example, the central axis AX of the arm 80 is fixed to the fixed base ST in a state facing the Z direction. The arm 80 is fixed to the arm mounting member 70 . The arm mounting member 70 is fixed to the upper end of the shaft 63 described later through bolts. The actuator 1 moves the arm 80 up and down in the Z direction (direction of linear motion, axis direction of the central axis AX), and moves the arm 80 in a direction around the central axis AX in a plane orthogonal to the Z direction. Rotate along the axis. Since the workpiece (not shown) is mounted on the arm 80, the workpiece can be transferred to a desired position.

The first motor M1 has a first stator 10 , a first rotor 20 , a first motor housing 40 and a first rotation detector 101 .

A first stator holder 11 is arranged radially inside the first stator 10 . The first stator 10 is fixed to the 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 has a first rotor bracket 21 and a first rotor core 22 fixed on the radial inner side of the first rotor bracket 21 and having a permanent magnet. The first rotor bracket 21 is formed in a cylindrical shape with the central axis AX as the center. Furthermore, the first rotor bracket 21 has an outer race retainer 21a that supports the outer race of the first bearing 31.

The first stator 10 and the first rotor 20 are coaxially arranged with the central axis AX as the center. The first rotor 20 is arranged radially outside the first stator 10 and the first stator holder 11 and relatively rotates 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 through the first bearing 31 . The first stator holding body 11 is fixed to the first motor housing 40 through bolts. The first stator 10 is arranged in a cylindrical shape around the central axis AX.

The first motor housing 40 is formed in 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 cover member 111 is provided at the opening. The first cover member 111 is fixed to the outer race clamp 21a of the first rotor bracket 21 through bolts. A through hole is provided in the radial center portion of the first cover member 111 , and the through hole is covered by the spline outer cylinder 61 . The lower surface of the first cover member 111 is provided with a recessed portion 112 that is concave upward.

A flange 62 extending in the radial direction is provided at the lower end of the spline outer cylinder 61 . In a state where the flange 62 has been inserted into the recess 112 , the flange 62 is fixed to the first cover member 111 through bolts. Furthermore, the upper end of the first motor housing 40 is provided with a mounting flange 40 a extending toward the radially outer side. The mounting flange 40a is placed on the upper surface of the fixing base ST and can be fixed to the fixing base ST through bolts. A slight gap is formed between the outer peripheral end of the first cover member 111 and the inner peripheral end of the first motor housing 40 , and the first cover 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 part 101 is arranged above the first bearing 31 .

The second motor M2 is arranged side by side with respect to the first motor M1 in the axial direction of the central axis AX. The second motor M2 includes a second stator 10A, a second rotor 20A, a second motor housing 40A, and a second rotation detector 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 has 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 in a cylindrical shape with the central axis AX as the center. The second stator 10A and the second rotor 20A are coaxially arranged with the central axis AX as the center.

The second rotor 20A is arranged radially outside the second stator 10A and the second stator holder 11A, and relatively rotates 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 through the second bearing 32 . The second stator 10A is fixed to the second stator holder 11A arranged radially inside the second stator 10A. The second stator holding body 11A is fixed to the second motor housing 40A through bolts. The second stator 10A is arranged in a cylindrical shape around the central axis AX.

Here, the shaft member SF will be described. The shaft member SF has an upper shaft 63 and a lower screw shaft 53. The shaft 63 extends from the arm mounting member 70 to the connecting portion 100 in the axial direction of the central axis AX. The connection part 100 is provided in parallel with the second rotation detection part 101A. The shaft 63 has a large diameter part 631 and a small diameter part 632. The large diameter portion 631 extends from the arm mounting member 70 to the lower bottom 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 toward the axial direction of the central axis AX are provided at intervals in the circumferential direction. A spline portion (not shown) is provided on the inner circumferential side of the spline outer cylinder 61 , and the spline portion has a plurality of convex portions that can engage with the spline groove portion 633 . In this way, the shaft member SF has the first portion S1 that protrudes upward in one of the axial directions from the first rotor 20 toward the opposite side of the second rotor 20A. The first part S1 is provided with a spline groove portion 633 extending in the axial direction. The spline groove portion 633 and the spline portion are engaged through a plurality of balls, whereby the shaft member SF can be guided along the spline portion toward the axial direction, and the shaft member SF can rotate together with the first rotor 20 to rotate the shaft. The member SF rotates in the axial direction about the central axis. Furthermore, the small diameter portion 632 extends from the lower end of the large diameter portion 631 to the connecting portion 100 . In this way, in the first part S1, the rolling guide ball spline can be applied.

The screw shaft 53 extends from the connecting portion 100 to the stopper 55 . The screw shaft 53 has an upper large diameter part 531 and a lower small diameter part 532. A small diameter portion 531a protruding upward is provided at the front end portion (the upper end portion in FIG. 1 ) of the large diameter portion 531 of the screw shaft 53. An external thread is provided on the outer periphery of the small diameter portion 531a. A recessed portion 632a is provided at the lower end of the small diameter portion 632 of the shaft 63 . An internal thread meshing with the external thread of the small diameter portion 531a is provided on the inner periphery of the recessed portion 632a. The internal thread on the inner circumference of the recessed portion 632a is engaged with the external thread of the small diameter portion 531a. Thereby, the small diameter part 632 of the shaft 63 and the large diameter part 531 of the screw shaft 53 can be integrally connected. That is, the shaft 63 and the screw shaft 53 can be connected by screw fastening. Furthermore, a male thread portion 533 is formed on the outer circumference of the large diameter portion 531 . That is, the shaft member SF has a second portion S2 that protrudes from the second rotor 20A toward the opposite side of the first rotor 20 and is provided below the other side in the axial direction. There is an external thread part 533. In addition, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the external thread portion 533. Furthermore, the diameter D1 of the spline groove portion 633 is the larger diameter among the major diameter and the minor diameter. The diameter D2 of the external thread portion 533 is the outer diameter and the inner diameter (small diameter).

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

The nut shell 42 has an upper flange 42a; a cylindrical portion 42b formed in a cylindrical shape extending downward from the inner peripheral end of the upper flange 42a; and a bottom 42c formed from the cylindrical portion 42b. The lower end extends toward the inner peripheral side. The upper end flange 42a is fixed to the lower bottom 40Ab of the second motor housing 40A through bolts. The stopper cover 44 is fixed to the bottom 42c of the nut housing 42 through bolts. The bottom 42c is provided with a through hole, and the small diameter portion 532 of the screw shaft 53 is provided therethrough.

A stopper 55 is installed at the lower end of the small diameter portion 532 via a nut 56 . The stopper 55 is a circular ring-shaped member. The stopper 55 is inserted into the screw shaft 53 . A circular ring-shaped buffer member 55a is arranged on the upper side of the stopper 55 in the Z direction. The buffering member 55a is, for example, elastomer urethane rubber. As the shaft member SF rises, the stopper 55 comes into contact with the bottom 42c of the nut housing 42 through the buffer member 55a, thereby restricting the rise of the shaft member SF. Inside the nut housing 42, the nut member 51 and the second connection bracket 45 are accommodated.

An internal thread portion is provided on the inner peripheral side of the nut member 51 . The internal thread portion meshes with the external thread portion 533 of the second portion S2 of the shaft member SF through a plurality of balls. The second connection bracket 45 is arranged radially outside the nut member 51 . A flange portion 51 a extending radially outward is formed at the lower end of the nut member 51 . The flange portion 51a is fixed to the second connecting bracket 45 through balls. The upper end of the second connecting bracket 45 is provided with a flange 45a that expands toward the radially outer side, and the flange 45a is fixed to the first connecting bracket 46 through bolts. Thus, in the second part S2, a rolling-guided ball screw can be used.

The first connection bracket 46 is fixed to the second rotor bracket 21A through bolts. In this way, the nut member 51, the second connection bracket 45, the first connection bracket 46, and the second rotor bracket 21A can be rotated as one body. Specifically, the nut member 51 , the second connecting bracket 45 , the first connecting bracket 46 and the second rotor bracket 21A are rotatably supported by the second stator 10A and the second stator holder through the second bearing 32 11A.

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 part 101A is arranged in a position parallel to the connection part 100 in the axial direction.

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

First, the manner in which the shaft member SF moves up and down (linearly moves) will be described. In this mode, only the second motor M2 is activated, and the first motor M1 is not activated.

As shown in FIG. 1 , when the second motor M2 is activated, the second rotor 20A rotates in the axial direction about the central axis AX. Specifically, the second rotor 20A rotates around the central axis AX relative to the second stator 10A and the second stator holder 11A through the second bearing 32 . Furthermore, 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 in the axial direction about the central axis AX integrally with the second rotor 20A. Since the internal thread portion of the nut member 51 is engaged with the external thread portion 533 of the second portion S2 of the shaft member SF, the shaft member SF will linearly move in the axial direction by the rotation of the nut member 51 . Specifically, as shown in FIG. 2 , the shaft member SF rises in the axial direction. Furthermore, in this state, as the shaft member SF still rises, the stopper 55 contacts the bottom 42c of the nut housing 42 through the buffer member 55a, thereby restricting the rise of the shaft member SF.

Next, the manner in which the shaft member SF turns (rotates) will be described. This aspect includes a first aspect, a second aspect, and a third aspect depending on the movement method of the shaft member SF in the Z direction.

In the first aspect, the first motor M1 is activated, but the second motor M2 is not activated. As mentioned above, the spline groove part 633 meshes with the spline part. Thereby, the shaft member SF is guided in the axial direction along the spline portion of the spline outer cylinder 61 . In addition, the shaft member SF rotates together with the first rotor 20 through the spline outer cylinder 61, so that the shaft member SF can rotate in the axial direction about the central axis AX. Furthermore, since the second motor M2 does not operate, the nut member 51 does not rotate. When the shaft member SF rotates according to the spline outer cylinder 61, the shaft member SF linearly moves in the axial direction via the nut member 51. From the above, in the first aspect, the shaft member SF linearly moves in the Z direction by rotating integrally with the spline outer cylinder 61 and relatively rotating with the stationary nut member 51 .

In the second aspect, the shaft member SF rotates integrally with the spline outer cylinder 61 and simultaneously rotates the nut member 51 so that the position of the shaft member SF in the Z direction does not change. Therefore, in the second aspect, both the first motor M1 and the second motor M2 are operated. That is, the rotation system performed by the first motor M1 is the same as the first aspect, and the shaft member SF rotates together with the first rotor 20 through the spline outer cylinder 61, whereby the shaft member SF can be directed toward the center. Rotate around the axis AX. Although the second motor M2 is not actuated in the first aspect, it causes the nut member 51 to rotate in a direction opposite to the direction in which the shaft member SF linearly moves. Based on the above, in the second aspect, the shaft member SF rotates integrally with the spline outer cylinder 61 without changing the position of the shaft member SF in the Z direction.

In the third aspect, while the shaft member SF rotates integrally with the spline outer cylinder 61, the rotation speed of the nut member 51 is appropriately adjusted, thereby making the shaft member SF linearly move at a speed (moving speed in the Z direction). ) variable. Therefore, in the third aspect, both the first motor M1 and the second motor M2 are operated. That is, the rotation performed by the first motor M1 is the same as in the first and second aspects, and the shaft member SF rotates together with the first rotor 20 through the spline outer cylinder 61, whereby the shaft member SF can be directed toward Rotate around the central axis AX in the axial direction. The rotation speed of the second motor M2 is set in accordance with the desired linear motion speed of the shaft member SF. Based on the above, in the third aspect, the shaft member SF and the spline outer cylinder 61 are rotated integrally while appropriately adjusting the moving speed of the shaft member SF in the Z direction.

As described above, the actuator 1 of this embodiment is provided with a first motor M1 having a first stator 10 and a first rotor 20 . The first rotor 20 is located relative to the first stator 10 . The second motor M2 is capable of rotating in the circumferential direction with the central axis AX as the center; and the second motor M2 is arranged separately from the first motor M1 in the axial direction of the central axis AX and has a second stator 10A and a second motor M2. The rotor 20A, the second rotor 20A is rotatable relative to the second stator 10A and is arranged coaxially with the central axis AX of the first rotor 20; and the shaft member SF penetrates the first rotor 20 and the second rotor 20 in the axial direction. The rotor 20A is provided with a spline groove portion 633 extending in the axial direction at at least a portion of the first portion S1 that protrudes in one direction in the axial direction from the first rotor 20 toward the opposite side of the second rotor 20A. 20A is provided with an external thread portion 533 at at least a part of the second portion S2 protruding on the other side in the axial direction toward the opposite side of the first rotor 20; and a spline outer cylinder 61, which is a spline groove portion with the shaft member SF. 633 engages and guides the shaft member SF in the axial direction along the spline groove portion 633, and rotates together with the first rotor 20 to rotate the shaft member SF in the axial direction about the central axis AX; and the nut member 51 , which is provided with an internal thread portion that meshes with the external thread portion 533 of the shaft member SF, and rotates together with the second rotor 20A to move the shaft member SF toward the axial direction of the central axis AX.

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

In addition, the diameter of the spline groove portion 633 in the shaft member SF is larger than the diameter of the external thread portion 533.

The spline outer cylinder 61 rotates in the axial direction about the central axis AX by the driving force of the first motor M1, 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. In addition, when the rotation operation of the shaft member SF is performed before the shaft member SF reaches the predetermined position in the circumferential direction, the time until the shaft member SF is positioned at the final predetermined position can be 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 vibration and inclination of the output shaft of the first motor M1 are less likely to affect the spline outer cylinder 61, and the spline outer cylinder 61 can be assembled with high accuracy. The vibration and inclination of the output shaft of the second motor M2 will not easily affect the nut member 51, and the nut member 51 can be assembled with high precision.

Since the first motor M1 and the second motor M2 are separated, the torques of the respective motors can be set individually.

A spline outer cylinder 61 is provided on one end side of the shaft member SF, and a nut member 51 is provided on the other end side. Therefore, compared with 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 vibration of the shaft member SF caused by the rotation of the spline outer cylinder 61 and the nut member 51 Or the tilt will become smaller.

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

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

When the shaft 63 or the screw shaft 53 is worn or the like, only the worn components need 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 transmits the generated driving force directly to the object without passing through a reduction mechanism. That is, the shaft member SF can be rotated by directly rotating the spline outer cylinder 61 by the driving force of the first motor M1. In addition, the nut member 51 is directly rotated by the driving force of the second motor M2, thereby allowing the shaft member SF to linearly move.

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

Since the spline outer cylinder 61 engaged with the spline groove portion 633 is provided in the first portion S1 of the shaft member SF, vibration or inclination when the shaft member SF rotates is reduced. Therefore, since the vibration and inclination of the arm mounting member 70 and the arm portion 80 during rotation are also reduced, the workpiece can be stably rotated and raised and lowered.

[Second Embodiment] Next, the actuator 1A of the second embodiment will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted. The following description will focus on the differences from the first embodiment.

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

The structure of the shaft member SF of the second embodiment is different from that of the first embodiment. That is, in the first embodiment, the shaft member SF is divided into the upper shaft 63 and the lower screw 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 thread fastening.

However, in the shaft member SF of the second embodiment, the upper shaft 63 and the lower screw shaft 53 are integrally connected. For example, the shaft member SF having the shape of the shaft 63 and the screw shaft 53 is formed by thinning the outer peripheral portion of a cylindrical metal member. In addition, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the external thread portion 533. Here, the diameter D1 of the spline groove portion 633 is the larger diameter among the larger diameter and the smaller diameter. The diameter D2 of the external thread portion 533 is the outer diameter and the inner diameter (small diameter).

In addition, the lifting, lowering and turning of the shaft member SF are the same as those in the first embodiment. In addition, at the lower limit position of the shaft member SF shown in FIG. 3 , when the second motor M2 is activated, the nut member 51 will also rotate together with the second rotor 20A, and as shown in FIG. 4 , the shaft member SF will move along the axis. direction upward.

As described above, in the actuator 1A of this embodiment, the shaft member SF is formed by integrally connecting the upper shaft 63 and the lower screw shaft 53 . Therefore, the rigidity of the shaft member SF becomes higher than the case where the shaft 63 and the screw shaft 53 are divided and connected.

[Third Embodiment] Next, the actuator 1B of the third embodiment will be described. The same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and descriptions thereof are omitted. The following description will focus on the differences from the first embodiment. Fig. 5 is a cross-sectional view of the actuator according to the third embodiment. FIG. 6 is an enlarged cross-sectional view of the main part of FIG. 5 . FIG. 7 is an enlarged cross-sectional view of another main part of FIG. 5 . FIG. 8 is a cross-sectional view of the actuator according to the third embodiment, showing a state in which the stroke of the shaft member is at the upper limit.

In this embodiment, the portion above the first motor M1 (shown in detail in FIG. 6 ) and the portion below the nut member 51 (shown in detail in FIG. 7 ) are mainly different from those in the first embodiment and The second embodiment is different. The arm mounting member 70A is connected to the front end (upper end) of the shaft 63. The arm mounting member 70A has a connection part 71, a cylindrical part 72, and a cover part 73. The connecting part 71 is connected to the reduced diameter part 63a of the shaft 63.

As shown in FIG. 6 , the cylindrical portion 72 is formed into a cylindrical shape and is provided in a state extending downward from the connecting portion 71 . 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 recessed portion 72a is provided at the lower end of the cylindrical portion 72 . The recessed portion 72a is formed by enlarging the diameter of the lower end of the inner peripheral surface. A sealing portion 77 is arranged in the recessed portion 72a.

The sealing portion 77 seals the 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 sealing portion 77 include a structure in which a U-shaped or U-shaped member in cross-sectional view is formed into an annular shape. The sealing portion 77 is formed using, for example, an elastically deformable material. The shaft 63 is protected from external damage by the sealing portion 77 . Furthermore, a protruding portion 72b protruding inward is formed at the lower end portion of the recessed portion 72a. This protruding portion 72b can prevent the sealing portion 77 from falling.

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

The cover 73 is mounted on the cover mounting surface 71d of the connecting portion 71 with bolts. The cover portion 73 protects the reduced diameter portion 63a of the shaft 63 from external damage.

The spline outer cylinder housing 43 has a first cylindrical portion 431 and a second cylindrical portion 432 . In addition, the second cover member 111A is fixed to the upper end of the first rotor bracket 21 through bolts. The flange 62A of the spline outer cylinder 61A is fixed to the upper end of the second cover member 111A through bolts.

The first cylindrical part 431 has: a first cylindrical part 431b, which is arranged on the upper side in the up-down direction; a step part 431d, which is arranged on the lower side of the first cylindrical part 431b; and a second cylinder. The portion 431e is arranged below the step portion 431d.

The first cylindrical portion 431b is provided with a receiving portion 431a extending radially inwardly in an annular shape along the circumferential direction. The upper surface of the receiving portion 431a is provided with a concave portion that is concave downward, and the O-ring 74 is accommodated in the concave portion. When the lower end surface of the second cylindrical part 432 has pressed the O-ring 74, the lower end part of the second cylindrical part 432 is fixed to the receiving part 431a of the first cylindrical part 431 through bolts. A recessed portion is formed on the side surface of the lower end portion 431c of the second cylindrical portion 431e, and the O-ring 75 is accommodated in the recessed portion.

The O-ring 75 is pressed against the inner peripheral surface of the upper end of the first motor housing 40 . In this state, the lower end of the first cylindrical portion 431 is fixed to the upper end of the first motor housing 40 through bolts. Furthermore, a recessed portion dented toward the radially inward side is provided on the outer peripheral surface of the upper end portion of the first motor housing 40, and the O-ring 76 is accommodated in the recessed portion. In a state where the O-ring 76 is pressed against the inner peripheral surface of the fixed table ST, the mounting flange 40a of the first motor housing 40 is fixed to the upper surface of the fixed table ST through bolts.

As shown in FIG. 6 , in the first cylindrical part 431 , the third bearing 33 is held between the second cylindrical part 431 e and the connection bracket 34 . The connecting bracket 34 is fixed to the flange 62A of the splined outer cylinder 61A. Therefore, the third bearing 33 rotatably supports the spline outer cylinder 61A and the connection bracket 34. The third bearing 33 is, for example, a rolling bearing. The third bearing 33 is supported on the step portion 431d through a wave washer 39a and a pressing member 39b. The third bearing 33 is pressed against the connecting bracket 34 side by the wave washer 39a and the pressing member 39b. In addition, 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 described. The shaft member SF has an upper shaft 63 and a lower screw shaft 53. The shaft 63 extends from the arm mounting member 70A to the connecting portion 100 in the axial direction of the central axis AX. The connection part 100 is provided at a position parallel to the second rotation detection part 101A in the axial direction. The shaft 63 is formed by integrating the reduced diameter portion 63a, the large diameter portion 63b, and the small diameter portion 63c. The large-diameter part 63b has: a first large-diameter part 63b1, which is arranged below the reduced-diameter part 63a; and a second large-diameter part 63b2, which is accommodated inside the second cylindrical part 432; and a third large-diameter part 63b. The three large diameter portions 63b3 extend from the upper end of the spline outer cylinder 61A to the lower bottom 40b of the first motor housing 40. On the outer periphery of the third large diameter portion 63b3, a plurality of spline groove portions 633 extending in the axial direction of the central axis AX are provided at intervals in the circumferential direction. Furthermore, a portion where the spline groove portion 633 is provided to protrude 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 part 531 and a lower small diameter part 532. A small diameter portion 531 a protruding upward is provided at the front end of the large diameter portion 531 of the screw shaft 53 . An external thread is provided on the outer periphery of the small diameter portion 531a. A recessed portion 632a is provided at the lower end of the small diameter portion 632 of the shaft 63 . An internal thread meshing with the external thread of the small diameter portion 531a is provided on the inner periphery of the recessed portion 632a. The internal thread on the inner circumference of the recessed portion 632a is engaged with the external thread of the small diameter portion 531a. Thereby, the small diameter part 632 of the shaft 63 and the large diameter part 531 of the screw shaft 53 can be integrally connected. That is, the shaft 63 and the screw shaft 53 can be connected by screw fastening. Furthermore, a male thread portion 533 is formed on the outer circumference of the large diameter portion 531 . That is, the shaft member SF has a second portion S2 that protrudes from the second rotor 20A toward the opposite direction of the first rotor 20 and is provided below the other axial direction. There is an external thread part 533. Furthermore, no externally threaded portion is provided on the outer circumference of the small diameter portion 532 . In addition, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the external thread portion 533. Furthermore, the diameter D1 of the spline groove portion 633 is the larger diameter among the major diameter and the minor diameter. The diameter D2 of the external thread portion 533 is the outer diameter and the inner diameter (small diameter).

As shown in FIG. 7 , the clamping mechanism 130 includes a small diameter portion 532 of the screw shaft 53 , a collet 132 and a pressure cylinder 134 . The collet 132 includes a clamping portion 132A capable of deforming in the radial direction and a substantially cylindrical flange portion 132B. Four grooves are formed in the clamping portion 132A in the Z direction. The cross-sectional view shown in FIG. 7 shows a cross-section cut along the groove. Slots are formed at different 90-degree positions in the circumferential direction. Thereby, the clamping part 132A can elastically deform in the radial direction. Furthermore, the number, shape and position of the slots are not particularly limited. The groove may be formed so that the clamping part 132A can elastically deform in the radial direction.

The 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 recessed portion 132c, and an inner peripheral surface 132d. The first tapered surface 132a is the outer peripheral surface of the clamping portion 132A. The first tapered surface 132a is an inclined surface whose outer diameter decreases toward the lower side in the Z direction. In other words, the first tapered surface 132a has a substantially conical surface shape.

The second tapered surface 132b is the outer peripheral surface on the upper side in the Z direction of the flange portion 132B. 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 surface shape. The recessed portion 132c is a groove formed on the outer peripheral surface of the flange portion 132B. The recess 132c is formed in the Z direction between the first tapered surface 132a and the second tapered surface 132b. The inner peripheral surface 132d is a surface facing the clamped portion 53b of the screw shaft 53. The collet 132 is arranged so 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 limit in the axial direction.

The pressure cylinder 134 includes a piston 136, a pressure cylinder tube 138, a first sealing member 160 and a second sealing member 162. Furthermore, the pressure cylinder 134 is provided with a gas supply part 163, a fixing member 144, a stopper part 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 portion 136d, a lower surface 136e, a recessed portion 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 its 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 such a configuration, the inclined surface 136a can contact the first tapered surface 132a when the piston 136 has moved to the upper side in the Z direction. Then, when the inclined surface 136a is in contact with the first tapered surface 132a, it can press the first tapered surface 132a radially inward. That is, the inclined surface 136a is a clamping portion capable of pressing the clamping portion 132A radially inward. The inclined surface 136a is opposite to the first tapered surface 132a. That is, the inclined surface 136a and the first tapered surface 132a have substantially the same slope. The inclined surface 136a is arranged so as to overlap the first tapered surface 132a in the radial direction. Thereby, the size of the space occupied by the piston 136 and the collet 132 in the axial direction can be reduced.

The first outer surface 136b and the second outer surface 136c are the outer surfaces of the piston 136. The first outer surface 136b is located above the second outer surface 136c in the Z direction. The diameter of the second outer side 136c is larger than the diameter of the first outer side 136b. The first outer surface 136b and the second outer surface 136c are arranged to overlap the first tapered surface 132a in the radial direction. The groove portion 136d is an angular groove formed on 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. The lower surface 136e is formed with a recessed portion 136f that is concave upward in the Z direction. 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 also includes a cylindrical portion 138a, an outer diameter side flange portion 138b, an inner diameter side flange portion 138c, a groove portion 138d, a first inner side surface 138e, a second inner side surface 138f, and a gas supply path 138g. The cylindrical portion 138a is a cylindrical member. An outer diameter side flange portion 138b and an inner diameter side flange portion 138c are connected to an upper end portion in the Z direction of the cylindrical portion 138a. 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 the fixing member 140. The inner diameter side flange portion 138c is formed in an annular shape and is arranged radially inward of the outer diameter side flange portion 138b. A step surface 142 is formed in the inner diameter side flange portion 138c. The step surface 142 is formed at the upper end of the inner diameter side flange portion 138c in the Z direction. The step surface 142 is in the shape of a ring when viewed from the upper side in the Z direction.

The first inner side surface 138e is a radially inner side surface of the inner diameter side flange portion 138c. The first inner side 138e is opposite to the first outer side 136b. The second inner side surface 138f is the radially inner side surface of the cylindrical portion 138a. The diameter of the second inner side 138f is larger than the diameter of the first inner side 138e. The second inner side 138f is opposite to the second outer side 136c. The first inner side surface 138e and the second inner side surface 138f are arranged so as to overlap the first tapered surface 132a in the radial direction. The groove portion 138d is an angular groove formed on 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 penetrating from the outside of the pressure cylinder tube 138 to the inside of the pressure cylinder tube 138 . The gas supply pipe 158 is connected to the gas supply path 138g. The gas supply path 138g and the gas supply pipe 158 are screwed together through a seal tape, for example.

The first sealing member 160 is an O-ring. The first sealing member 160 is arranged in the groove portion 136d. The first sealing member 160 is embedded in 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 will be sealed.

The second sealing member 162 is an O-ring. The second sealing member 162 is arranged in the groove portion 138d. The second sealing member 162 is embedded in 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 will be 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 sealing member 160 and the third Two sealing members 162 surround the pressure chamber 139 .

The gas supply part 163 is an air compressor (compressor) that supplies compressed air. The gas supply part 163 is connected to the gas supply pipe 158. In addition, the gas supplied by the gas supply part 163 is not limited to compressed air. The gas supply unit 163 may supply compressed nitrogen gas, for example.

The fixed member 144 is a circular ring-shaped plate member. The fixing member 144 is arranged so that the radially outer lower surface contacts the step surface 142 . Furthermore, the fixing member 144 has its radially inner end inserted into the recessed portion 132c.

The stopper part 146 is a circular ring-shaped member. The small diameter portion 52B of the screw shaft 53 is inserted into the stopper portion 146 . The stopper portion 146 has an inclined surface 146a facing the second tapered surface 132b. Thereby, the stopper portion 146 can restrict the upward movement of the collet 132 in the Z direction. Moreover, the stopper part 146 is fixed to the inner diameter side flange part 138c by the fixing member 148 in the state which sandwiched the fixing member 144 with the step surface 142. Therefore, the stopper portion 146 fixes the position of the fixing member 144 in the Z direction. Then, the end portion on the inner diameter side of the fixing member 144 is inserted into the recessed portion 132c. According to this, the fixing member 144 can restrict the movement of the collet 132 downward in the Z direction. With such a configuration, the position of the collet 132 in the Z direction can be determined.

The screw shaft housing 150 is fixed to the fixing table ST through the cylinder tube 138, the nut housing 42, the motor housing 41, and the spline outer cylinder housing 43. The screw shaft housing 150 has a flange portion 150a, a flange surface 150b, a cylindrical portion 150c, a recessed portion 150d, and a cover member 150e. The flange portion 150a is formed into 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 an upper surface of the flange portion 150a in the Z direction.

The flange surface 150b is opposite to the lower surface 136e. The cylindrical portion 150c extends downward from the inner circumference of the flange portion 150a. As shown in FIG. 5 , the cylindrical portion 150 c accommodates the lower end of the screw shaft 53 . The recessed portion 150d is a recessed portion that is dented downward in the Z direction from the flange surface 150b. The cover member 150e is a member that blocks the lower side of the cylindrical portion 150c in the Z direction. The cover member 150e is fixed to the lower end surface of the cylindrical portion 150c in the Z direction by bolts. This prevents foreign matter from intruding into the inside of 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 is in contact with the bottom surface of the recess 136f. The other end of the spring 156 is in contact with the bottom surface of the recess 150d. Therefore, the spring 156 can be compressed by the bottom surface of the recessed portion 136f and the bottom surface of the recessed portion 150d. Since the screw shaft housing 150 is fixed to the fixing table ST, the bottom surface of the recessed portion 150d does not move downward in the Z-axis direction. Therefore, the spring 156 presses the piston 136 upward in the Z direction. In addition, although the spring 156 is assumed to be a compression coil spring, it is not limited to this. The spring 156 may be an elastic member that urges the piston 136 toward the direction in which the piston 136 approaches the clamping portion 132A. The spring 156 may be a square spring or a conical spring, for example. In addition, a plurality of springs 156 may be arranged.

The stopper 55 is installed on the lower end of the screw shaft 53 through a nut 56 . The stopper 55 is a circular ring-shaped member. The stopper 55 is inserted into the screw shaft 53 . A circular ring-shaped buffer member 55a is arranged on the upper side of the stopper 55 in the Z direction. The buffer member 55a is, for example, elastomer 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 only by a predetermined length, the stopper 55 comes into contact with the flange portion 150a through the buffer member 55a. Thereby, the stopper 55 can prevent the screw shaft 53 from rising beyond a predetermined length.

Furthermore, the lifting, lowering and turning of the shaft member SF are also the same as those in the first and second embodiments. In addition, in the lower limit position of the shaft member SF shown in FIG. 5 , when the second motor M2 is activated, the nut member 51 also rotates together with the second rotor 20A, and as shown in FIG. 8 , the shaft member SF moves along The axis direction rises.

As explained above, the actuator 1B of this embodiment is equipped with the clamping mechanism 130. The clamping mechanism 130 includes: a collet 132 through which the second part S2 of the shaft member SF passes; and a pressure cylinder 134. It is an elastic member having a piston 136 through which the second part of the shaft member SF passes, a cylinder tube 138 accommodating the piston 136, and a biasing piston 136. The piston 136 has an inclined surface 136a (clamping part), and the inclined surface 136a is in contact with the outer peripheral surface of the collet 132 through an elastic member, thereby pressing the collet 132 against the shaft member SF; the collet 132 is When gas or liquid is supplied inside the cylinder tube 138, it is separated from the shaft member SF.

According to this structure, the elastic member can urge the clamping portion so as to come into contact with the outer peripheral surface of the collet 132 . Then, the clamping part can press the collet 132 against the shaft member SF to clamp the shaft member. In addition, since the clamping portion is configured to be in contact with the outer peripheral surface of the collet 132, it overlaps with the outer peripheral surface in the radial direction. With such a structure, the size of the clamping mechanism 130 in the axial direction can be reduced. Furthermore, by supplying gas or liquid into the inside of the cylinder tube 138, the shaft member SF can be loosened. Furthermore, even when the power supply is cut off, the clamping mechanism 130 can still hold the shaft member SF.

The outer peripheral surface is a tapered surface whose diameter becomes smaller as it approaches the clamping portion; the clamping portion is a first tapered surface 132a (inclined surface) facing the outer peripheral surface.

According to this configuration, the first tapered surface 132a can come into surface contact with the tapered surface when gas or liquid is not supplied to the inside of the cylinder tube 138. This can also increase the friction force generated between the collet 132 and the clamping section compared to the case where the outer circumferential surface of the collet 132 is in line contact or point contact with the clamping section. Therefore, when the collet clamps the shaft member SF, the outer peripheral surface of the collet 132 and the clamping portion can be suppressed from sliding.

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

For example, when the workpiece is supported by the arm 80 and the center of gravity of the load of the arm 80 and the workpiece does not coincide with the central axis AX, or when the rotational moment of the arm 80 and the workpiece is received, it is possible to The shaft member SF receives force in a direction inclined with respect to the central axis AX. In contrast, 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 through the wave washer 39a and the pressing member 39b, the spline outer cylinder 61A can be suppressed from moving forward. Radial displacement or vibration orthogonal to the axis direction of the central axis AX.

A cylindrical gap is formed between the cylindrical portion provided on the arm mounting member 70A fixed to the front end of the first portion S1 and covering the outer periphery of the first portion S1.

Since the labyrinth structure is formed between the first part S1 and the outside of the cylindrical gap through the cylindrical gap, the dustproof and waterproof properties of the inside of the arm mounting member 70A can be improved.

[Fourth Embodiment] Next, an actuator 1C according to the fourth embodiment will be described. The same components as those in the first embodiment, the second embodiment, and the third embodiment are denoted by the same reference numerals, and descriptions thereof are omitted. The following description will focus on the differences from the third embodiment.

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

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

That is, in the third embodiment, the shaft member SF is divided into the upper shaft 63 and the lower screw 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 thread fastening.

However, in the shaft member SF of the fourth embodiment, the upper shaft 63 and the lower screw shaft 53 are integrally connected. For example, the shaft member SF having the shape of the shaft 63 and the screw shaft 53 is formed by thinning the outer peripheral portion of a cylindrical metal member. In addition, the diameter D1 of the spline groove portion 633 in the shaft member SF is larger than the diameter D2 of the external thread portion 533. Here, the diameter D1 of the spline groove portion 633 is the larger diameter among the larger diameter and the smaller diameter. The diameter D2 of the external thread portion 533 is the outer diameter and the inner diameter (small diameter).

In addition, the raising, lowering, and turning of the shaft member SF are the same as those in the first embodiment, the second embodiment, and the third embodiment. In addition, at the lower limit position of the shaft member SF shown in FIG. 9 , when the second motor M2 is activated, the nut member 51 will also rotate together with the second rotor 20A, and as shown in FIG. 10 , the shaft member SF will move along the axis. direction upward.

As described above, in the actuator 1C of this embodiment, the shaft member SF is formed by integrally connecting the upper shaft 63 and the lower screw shaft 53 . Therefore, the rigidity of the shaft member SF becomes higher than the case where the shaft 63 and the screw shaft 53 are divided and connected.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-mentioned embodiments. For example, in the shaft member SF, the shaft 63 and the screw shaft 53 are connected by screw fastening. However, the end of the shaft 63 may be press-fitted into the end of the screw shaft 53 to be connected. Furthermore, an adhesive may be used to connect the shaft 63 and the screw shaft 53 .

1,1A,1B,1C:actuator 10: First stator 10A: Second stator 11: First stator retaining body 11A: Second stator retaining body 20:First rotor 20A: Second rotor 21:First rotor bracket 21A: Second rotor bracket 21a: Outer race clamp 22:First rotor core 22A: Second rotor core 31:First bearing 32:Second bearing 33: Third bearing (rolling bearing) 34:Connecting bracket 39a: Wave washer 39b: Compression member 40:First motor housing 40A: Second motor housing 40Aa: upper bottom 40a: Installation flange 40Ab, 40b: lower bottom 41: Motor housing 42: Shell for nut 42a:Upper flange 42b,72,138a,150c:cylindrical part 42c: bottom 43: Shell for spline outer cylinder 44: Cover for stopper 45:Second link bracket 45a,62,62A:Flange 46:First link bracket 51: Nut component 52B, 63c, 532, 632: Small diameter part 53:Screw shaft 53b: Clamped part 55:stop 55a:Buffering member 56: Nut 61,61A:Spline outer barrel 63:Shaft 63a: Reduced diameter part 63b,531,631: Large diameter part 63b1: The first large diameter part 63b2: The second largest diameter part 63b3: The third largest diameter part 70,70A: Arm mounting member 71,100:Link Department 71d: Cover mounting surface 72a,112,132c,136f,150d,632a: concave part 72b:Protrusion 73: Cover 74~76:O-ring 77:Sealing part 80:Arm 101: First rotation detection part 101A: Second rotation detection part 111: First cover member 111A: Second cover member 130: Clamping mechanism 132:Collet 132A: Clamping part 132a: First tapered surface 132B,150a: Flange part 132b: Second tapered surface 132d: Inner peripheral surface 134: Press cylinder 136:Piston 136a: Inclined surface 136b: first outer side 136c: Second outer surface 136d: Groove part 136e: Lower surface 136g: upper surface 138: Press cylinder tube 138b: Outer diameter side flange part 138c: Inner diameter side flange part 138d: Groove part 138e: First medial surface 138f: Second medial surface 138g: Gas supply path 139:Pressure chamber 142: Step difference surface 144,148: Fixed components 146: Stopper part 146a: Inclined surface 150: Housing for screw shaft 150b: Flange surface 150e: Cover member 156:Spring 158:Gas supply piping 160: First sealing member 162: Second sealing member 163:Gas Supply Department 431: First cylindrical part 431a: Undertaking Department 431b: First cylindrical part 431d: Step difference department 431e: Second cylindrical part 432: Second cylindrical part 432a: Upper part of the second cylindrical part 531a: Small diameter part 533: External thread part 633:Spline groove part AX: central axis D1: Diameter of spline groove part D2: Diameter of external thread part M1: first motor M2: Second motor S1:Part One S2:Part Two SF: shaft member ST: fixed table

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

1C: Actuator

10: First stator

10A: Second stator

11: First stator retaining body

11A: Second stator retaining body

20:First rotor

20A: Second rotor

21:First rotor bracket

21A: Second rotor bracket

21a: Outer race clamp

22:First rotor core

22A: Second rotor core

31:First bearing

32:Second bearing

40:First motor housing

40A: Second motor housing

40Aa: upper bottom

40Ab, 40b: lower bottom

42: Shell for nut

42a:Upper flange

42b: Cylindrical part

43: Shell for spline outer cylinder

45:Second link bracket

45a,62A:Flange

46:First link bracket

53:Screw shaft

55:stop

61A:Spline outer barrel

63:Shaft

63a: Reduced diameter part

63b1: The first large diameter part

63b2: The second largest diameter part

63b3: The third largest diameter part

70A: Arm mounting member

71:Connection Department

72:Tubular part

73: Cover

101A: Second rotation detection part

111A: Second cover member

130: Clamping mechanism

150: Housing for screw shaft

431: First cylindrical part

432: Second cylindrical part

432a: Upper part of the second cylindrical part

531:Large diameter part

532,632:Trail Department

533: External thread part

633:Spline groove part

AX: central axis

M1: first motor

M2: Second motor

S1:Part One

S2:Part Two

SF: shaft member

ST: fixed table

Claims (8)

An actuator, characterized in that it is provided with: a first motor having a first stator and a first rotor, the first rotor being oriented in an axial direction around a central axis relative to the first stator. and a second motor, which is arranged separately from the first motor in the axial direction of the central axis, and has a second stator and a second rotor, and the second rotor is capable of rotating relative to the second stator. The rotor rotates and is arranged coaxially with the central axis of the first rotor; and a shaft member that penetrates the first rotor and the second rotor in the axial direction in the opposite direction from the first rotor to the second rotor. At least a part of the first part protruding in one side of the aforementioned axial direction is provided with a spline groove portion extending in the aforementioned axial direction, and protruding in the other side in the aforementioned axial direction from the second rotor toward the opposite side of the first rotor. At least a part of the second part of one side is provided with an externally threaded portion; and a splined outer cylinder that engages with the spline groove portion of the shaft member and guides the shaft member toward the axial direction along the spline groove portion. , and rotates together with the first rotor to rotate the shaft member in the axial direction about the central axis; and a nut member provided with an internal thread that engages with the external thread portion of the shaft member part, and rotates together with the second rotor to move the shaft member toward the axial direction of the central shaft; wherein the diameter of the spline groove part in the shaft member is larger than the diameter of the spline groove part of the shaft member. The diameter of the external thread portion is larger. The actuator of claim 1, wherein the shaft member is divided into a shaft including the first part and a screw shaft including the second part, and the shaft and the screw shaft are connected by threaded fastening. The actuator of claim 1, wherein an arm mounting member is fixed to an end of the first part of the shaft member, and the arm mounting member supports an arm for mounting the workpiece. The actuator of claim 1, wherein it is provided with a clamping mechanism, and the clamping mechanism includes: a collet, which is for the second part of the aforementioned shaft member to pass through; and a pressure cylinder, which is for the aforementioned shaft member to pass through. The second part penetrates the piston, the cylinder tube that accommodates the piston, and the elastic member that presses the piston; the piston has a clamping part, and the clamping part is in contact with the outer peripheral surface of the collet through the elastic member , whereby the collet is pressed against the shaft member; the collet is separated from the shaft member when gas or liquid is supplied to the inside of the cylinder tube. The actuator according to claim 4, wherein the outer peripheral surface is a tapered surface whose diameter becomes smaller as it approaches the clamping portion, and the clamping portion is an inclined surface facing the outer peripheral surface. The actuator of claim 1, wherein the radial outer side of the aforementioned spline outer cylinder is supported by the spline outer cylinder housing through a rolling bearing. Support. The actuator according to claim 1, wherein a cylindrical gap is formed between a cylindrical portion and the first portion, the cylindrical portion being provided on an arm mounting member fixed to a front end of the first portion and covering the first portion. The outer perimeter of the first part. The actuator according to any one of claims 1 to 7, wherein the first motor and the second motor are direct drive motors.

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