Actuators and Machines

Abstract

To provide an actuator which is capable of curve guiding while being space-saving and having a small number of components.SOLUTION: An actuator according to one aspect comprises: a guide; a slider movable along the guide on a front side of front and back sides of the guide; a conversion unit for converting a rotational motion of a screw shaft extending along the back side of the front and back sides of the guide to a linear motion of a nut; a plate spring which supports the nut such that the nut can tilt relatively to the slider, and transmits the linear motion to the slider; and a drive unit held on the guide at the back side, and drives the screw shaft to apply the rotational motion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an actuator and a machine. [Background technology]

[0002] A technique is known in which a curved guide is sandwiched between rollers provided on the slider, thereby moving the slider along the curved guide.

[0003] Patent Document 1 discloses an actuator that drives a slider on a curved rail with a linear motion feed mechanism. In this actuator, drive is transmitted from the linear motion feed mechanism to the slider via a pantograph-type transmission member.

[0004] Patent Document 2 discloses a three-dimensional guide device that moves a movable body such as a table along a predetermined curved surface in three-dimensional space. This three-dimensional guide device uses a transmission mechanism that includes a joint with a rotating shaft, a guide rail, etc. to transmit the linear motion of a ball screw to a saddle that moves along an arc-shaped rail.

[0005] Patent Document 3 discloses a positioning table for positioning rotation. In this positioning table, a linearly moving drive unit and the table are connected by a joint that uses a leaf spring as a flexible member. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-240773 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-230548 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-308771 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the techniques disclosed in Patent Documents 1 to 3, the actuator as a whole becomes large and complicated in order to enable curved guide, and there is a demand for an actuator that can provide curved guide in a small space and with a small number of parts. Therefore, an object of one aspect of the present invention is to provide an actuator capable of curved guide that saves space and requires a small number of parts. [Means for solving the problem]

[0008] In order to solve the above problem, an actuator according to one aspect of the present invention comprises: Has a curved section a guide; a slider that is movable along the guide on the front side of the guide; a conversion unit that converts the rotational movement of a screw shaft that extends along the back side of the guide into the linear movement of a nut; and a conversion unit that supports the nut so that it can tilt relatively to the slider and converts the rotational movement of a screw shaft that extends along the back side of the guide into the linear movement of a nut. Nut linear motion a leaf spring that transmits the movement to the slider, and a drive unit that is held by the guide on the back side and drives the screw shaft to provide the rotational movement.

[0009] According to the actuator, the leaf spring Nut linear motion By transmitting the movement, the curved guide can be realized with a small number of parts, and by appropriately arranging these parts on the front and back of the guide, space can be saved.

[0010] In addition, in an actuator according to one aspect of the present invention, the slider has an arm extending laterally from the front side to the back side of the guide, and the leaf spring connects the arm and the nut on the back side. With this configuration, motion can be transmitted from the conversion unit on the back side to the slider on the front side regardless of the structure of the guide.

[0011] According to an actuator according to an aspect of the present invention, the drive unit manually drives the screw shaft, which allows the screw shaft to be easily positioned at a desired position.

[0012] In addition, according to an actuator according to one aspect of the present invention, the drive unit drives the screw shaft using a motor with a brake, which allows the slider to continue to be held at the position it was positioned in even in a situation where power is not supplied to the motor, such as during a power outage.

[0013] The actuator according to one aspect of the present invention further includes a cover that covers the conversion unit, which can prevent foreign matter from entering the threaded portion of the conversion unit. Furthermore, a machine according to one aspect of the present invention includes any one of the actuators described above. [Effects of the Invention]

[0014] One aspect of the present invention is to provide an actuator capable of curved guide that requires less space and has fewer parts. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view showing an actuator according to one embodiment of the present invention. [Figure 2] FIG. 2 is a side view showing an actuator according to one embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view showing an actuator according to one embodiment of the present invention. [Figure 4] FIG. 4 is a side view showing a modified actuator. [Figure 5] FIG. 5 is a perspective view showing an actuator according to another embodiment. [Figure 6] FIG. 6 is a side view showing an actuator according to another embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing an actuator according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present invention, and not all combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be modified or changed as appropriate depending on the specifications of the device to which the present invention is applied and various conditions (such as usage conditions and usage environment). The technical scope of the present invention is defined by the claims and is not limited to the individual embodiments described below. Furthermore, the drawings used in the following description may differ in scale and shape from the actual structure to make each configuration easier to understand.

[0017] 1 to 3 are views showing an actuator according to an embodiment of the present invention, in which Fig. 1 shows a perspective view, Fig. 2 shows a side view, and Fig. 3 shows a cross section taken along line AA shown in Fig. 2. In the following embodiments, the guide that guides the slider is taken as an example of having a constant curvature in the vertical direction (tilt direction) relative to the guide surface of the guide, but the guide may also have a constant curvature in the horizontal direction (pant direction) relative to the guide surface of the guide.

[0018] The guide may have a portion having a constant curvature in the vertical direction relative to the guide surface of the guide and a portion having a constant curvature in the horizontal direction relative to the guide surface of the guide. The curvature of the curved portion of the guide may be constant, or the curvature of the curved portion of the guide may vary. good.

[0019] 1 to 3, actuator 10 drives and positions a moving body along a curved path. At this time, actuator 10 drives and positions the moving body by using a conversion unit that converts the rotational motion of the screw shaft into the linear motion of the nut. Furthermore, in order to eliminate mismatch between the curved motion of the moving body and the linear motion of the nut, actuator 10 supports the nut with a leaf spring so that the nut can tilt. In the field of medical equipment, for example, this actuator 10 can drive and position an X-ray irradiation head in an arc.

[0020] The actuator 10 includes a guide 11 , a slider 12 , a drive unit 13 , a leaf spring 16 and a ball screw 18 . The guide 11 guides the slider 12. The guide 11 has, for example, a curved portion in part. In this embodiment, the guide 11 has a guide surface with a constant curvature in the tilt direction, and guides the slider 12 along a circular arc trajectory.

[0021] Here, the guide 11 has a constant curvature in the tilt direction relative to the guide surface, so that the slider 12 can be moved along a trajectory with a constant radius, and a virtual center can be set. Therefore, the actuator 10 can move the slider 12 along a circular trajectory.

[0022] Rails 11A and 11B are provided on both sides of the guide 11, extending in an arc shape along the guiding direction of the guide 11. The material of the rails 11A and 11B can be, for example, carburized steel. A drive unit 13 that drives the slider 12 is provided on one end side of the guiding direction of the guide 11.

[0023] The slider 12 is movable along the front side of the guide 11. The slider 12 is driven and positioned via a ball screw 18. At this time, the slider 12 can be loaded with a payload such as an X-ray irradiation head.

[0024] The slider 12 includes a pair of housings 12A and 12B, a cover 12C, and an arm 12D. A pair of housings 12A, 12B protrude from cover 12C toward guide 11 and are located on either side of guide 11. Housings 12A, 12B support a plurality of cam followers JA1, JA2, JB1, and JB2 that sandwich guide 11 from four directions.

[0025] The cover 12C is installed so as to span the pair of housings 12A and 12B, and the above-mentioned load is placed on the cover 12C. The arm 12D extends from one housing 12A through the side of the guide 11 to the back side of the guide 11.

[0026] Cam followers JA1, JA2, JB1, and JB2 are used as rolling bearings that move slider 12 along guide 11. Note that, in this embodiment, an example is taken in which cam followers JA1, JA2, JB1, and JB2 are used as rolling bearings, but ball bearings or roller bearings may also be used as rolling bearings.

[0027] Rails 11A and 11B are provided with rail surfaces MA1, MA2, MB1, and MB2 adjacent to each other across ridgelines RA and RB extending along the rails 11A and 11B. Rail surfaces MA1, MA2, MB1, and MB2 also extend along the rails 11A and 11B, and rail surfaces MA1, MA2, MB1, and MB2 receive cam followers JA1, JA2, JB1, and JB2, respectively.

[0028] The cam followers JA1, JA2, JB1, and JB2 contact the rail surfaces MA1, MA2, MB1, and MB2 facing in four directions so as to sandwich the slider 12 from all four directions, allowing the slider 12 to move smoothly along the guide 11 without separating from the guide 11.

[0029] The ball screw 18 is used as a conversion unit that converts rotational motion into linear motion. The ball screw 18 includes a screw shaft 18A and a nut 18B. In this embodiment, the driving torque is reduced by using the ball screw 18 as the conversion unit, but a trapezoidal screw or a triangular screw may also be used as the conversion unit. The ball screw 18 is disposed on the rear side of the guide 11 opposite to the front side where the slider 12 is positioned.

[0030] The screw shaft 18A is driven by the driving force generated by the drive unit 13 to perform rotational motion. The nut 18B performs linear motion along the screw shaft 18A in accordance with the rotational motion of the screw shaft 18A. The leaf spring 16 connects the arm 12D and the nut 18B on the back side of the guide 11. As a result, the nut 18B is supported by the arm 12D of the slider 12 via the leaf spring 16. The support structure via the arm 12D allows motion to be transmitted from the ball screw 18 on the back side of the guide 11 to the slider 12 on the front side of the guide 11, regardless of the structure of the guide 11.

[0031] The screw shaft 18A and the nut 18B each have a screw groove. The screw groove of the screw shaft 18A is spirally provided on the outer peripheral surface of the screw shaft 18A. The screw groove of the nut 18B is spirally provided on the inner peripheral surface of the nut 18B so as to face the screw groove of the screw shaft 18A. In this case, the screw groove of the screw shaft 18A and the screw groove of the nut 18B form a spiral ball rolling path between the screw shaft 18A and the nut 18B.

[0032] The material of screw shaft 18A and nut 18B is not particularly limited as long as it is rigid, and may be, for example, a metal such as iron or an aluminum alloy, or a non-metal such as ceramic. The cross-sectional shape of the thread grooves of screw shaft 18A and nut 18B may be, for example, a circular arc shape or a Gothic arc shape.

[0033] The drive unit 13 has a motor 13A and a coupling 13B, and is fixed to the back side of the guide 11 via a casing 15. The motor 13A is connected to one end of the screw shaft 18A via the coupling 13B. With this structure, the slider 12 and the ball screw 18 are compactly integrated relative to the guide 11, realizing a space-saving actuator 10.

[0034] An AC servo motor, for example, may be used as motor 13A, but it is preferable to use a motor with a brake as motor 13A, as this allows the position of nut 18B to be maintained even when power is not supplied, such as during a power outage.

[0035] When the nut 18B and the slider 12 tilt relative to each other, the leaf spring 16 can absorb the tilt by its own deflection. That is, the simple holding structure of the leaf spring 16 allows the nut 18B and the slider 12 to tilt relative to each other, thereby reducing the number of parts in the actuator 10.

[0036] In the above configuration, when motor 13A rotates, the rotational motion of motor 13A is transmitted to screw shaft 18A via coupling 13B. Then, the rotational motion of screw shaft 18A causes linear motion of nut 18B, thereby driving slider 12. Furthermore, when the rotational motion of motor 13A is stopped, the rotational motion of screw shaft 18A stops, and accordingly the linear motion of nut 18B stops, thereby positioning slider 12.

[0037] At this time, slider 12 tilts in the tilt direction according to the curved shape of the curved portion of guide 11 in the tilt direction, but relative tilt is permitted because nut 18B is supported by slider 12 via leaf spring 16. Therefore, leaf spring 16 can eliminate mismatch between the curved movement of slider 12 in the tilt direction and the linear movement of nut 18B, and can ensure stability in the linear movement of nut 18B even when slider 12 tilts in the tilt direction.

[0038] In other words, even when the slider 12 moves along a guide 11 having a curved portion, the linear motion converted by the ball screw 18 can be transmitted to the slider 12, making it possible to drive and position the slider 12 along the curved guide 11.

[0039] Furthermore, when the slider 12 is driven, the cam followers JA1, JA2, JB1, and JB2 run on the surfaces MA1, MA2, MB1, and MB2 of the rails 11A and 11B, respectively. This allows the slider 12 to move in a curved line while being guided by the guide 11 while reducing friction with the guide 11.

[0040] Since multiple cam followers JA1, JA2, JB1, and JB2 are arranged to sandwich the guide 11 from four directions, it is possible to improve the holding force and rigidity of the slider 12 regardless of the direction of the running surface of the guide 11. Therefore, it is possible to improve the running stability, running accuracy, and positioning accuracy of the slider 12 without placing any restrictions on the installation angle of the guide 11.

[0041] For example, the guide 11 can be installed upright or inverted without reducing the running stability, running accuracy, and positioning accuracy of the slider 12. Therefore, for example, in the field of medical devices using X-ray irradiation, it becomes possible to drive and position the slider 12 while supporting helical scanning.

[0042] Each of the cam followers JA1, JA2, JB1, and JB2 may have an eccentric shaft. This allows preload to be applied to each of the cam followers JA1, JA2, JB1, and JB2, improving the running stability and running accuracy of the slider 12 along the guide 11. It is not necessary for all of the multiple cam followers provided on the slider 12 to have an eccentric shaft, and some of the cam followers provided on the slider 12 may have an eccentric shaft.

[0043] Next, a modified example of the actuator will be described. In the following, a duplicated description of elements equivalent to those of the actuator 10 of the above-described embodiment will be omitted, and the description will focus on the differences. FIG. 4 is a side view showing a modified example of the actuator. The actuator 20 of this modified example has a manual handle 13C instead of the motor 13A in the drive unit 13. The actuator 20 of this modified example allows manual adjustment and positioning of the slider 12. The actuator 20 of this modified example also uses the ball screw 18 as a conversion unit, so that position adjustment and positioning can be performed with a light force.

[0044] Next, another modified example of the actuator will be described. 5 to 7 are diagrams showing other modified examples of the actuator, in which Fig. 5 shows a perspective view, Fig. 6 shows a side view, and Fig. 7 shows a cross section taken along line AA shown in Fig. 6. 5 to 7 includes a conversion unit cover 19 that covers a ball screw 18 serving as a conversion unit. The conversion unit cover 19 has a slit 19A through which the leaf spring 16 passes. The width of the slit 19A is set to a width that allows the leaf spring 16 to pass through and allows sufficient deflection of the leaf spring 16.

[0045] The converter cover 19 prevents dust and other foreign matter from entering the thread groove of the ball screw 18, ensuring stability in the linear motion of the nut 18B by the ball screw 18. As a result, stability is also ensured in the driving of the slider 12 by the ball screw 18.

[0046] Although the actuators in the above-described embodiments are provided with guide 11 having a curved portion, guide 11 may also be linear. Even with linear guide 11, slider 12 may tilt if slider 12 rides over a foreign object on rails 11A and 11B or if distortion occurs in linear rails 11A and 11B.

[0047] In this way, even if the slider 12 tilts unexpectedly from the designed attitude, the nut 18B is supported by the leaf spring 16, so that unexpected loads on the nut 18B and the screw shaft 18A are avoided, and the stability of the linear motion of the nut 18B can be ensured.

[0048] Although the actuator in each of the above-described embodiments has the arm 12D of the slider 12 on one side of the guide 11, the arm 12D may be provided on both sides of the guide 11. In this case, the leaf spring 16 is also provided on both sides of the nut 18B, so that the nut 18B is supported from both sides.

[0049] The actuators of the above-described embodiments are incorporated into various types of machinery, such as medical equipment such as CT scanners, semiconductor manufacturing equipment, machine tools, optical equipment such as telescopes, and light projectors, and are used to drive and position mechanical elements along linear or curved guides. Use of the actuators of the above-described embodiments enables stable drive and positioning of mechanical elements.

[0050] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and includes various modifications. For example, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0051] 10, 20, 30 Actuator, 11 Guide, 11A, 11B Rail, 12 Slider, 12A, 12B Housing, 12C Cover, 13 Drive Unit, 13A Motor, 13B Coupling, 15 Casing, 16 Leaf Spring, 18 Ball Screw, 18A Screw Shaft, 18B Nut, 19 Converter Cover, JA1, JA2, JB1, JB2 Cam Follower, MA1, MA2, MB1, MB2 Rail Surface

Claims

1. A guide having a curved portion; a slider that is movable along the guide on the front side of the guide; A conversion unit that converts the rotational motion of a screw shaft extending along the back side of the guide into the linear motion of a nut; a leaf spring that supports the nut so as to be tiltable relative to the slider and transmits the linear motion of the nut to the slider; a drive unit that is held by the guide on the back side and drives the screw shaft to provide the rotational motion; An actuator comprising:

2. the slider has an arm extending laterally from the front side to the back side of the guide, The actuator according to claim 1 , wherein the leaf spring connects the arm and the nut at the rear side.

3. The actuator according to claim 1 or 2, wherein the drive unit manually drives the screw shaft.

4. 3. The actuator according to claim 1, wherein the drive unit drives the screw shaft using a motor with a brake.

5. The actuator according to claim 1 , further comprising a cover that covers the conversion unit.

6. A machine comprising the actuator according to any one of claims 1 to 5.

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