JP2012154446A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compress a coil spring evenly without buckling.SOLUTION: An electric actuator 11 is equipped with a conversion mechanism for converting a rotation motion of a motor 14 to a linear motion of a rod 21. The conversion mechanism includes a shaft member 15 connected to a rotation shaft 14a of the motor 14, a coil spring 22 disposed inside the rod 21, and pins 25, 26 which are supported by the shaft member 15 and which transmit the rotation motion of the shaft member 15 to the coil spring 22 and the rod 21. When the pins 25, 26 rotate with the rotation of the shaft member 15 and the coil spring 22 is compressed, the pins 25, 26 tilt along the inclination angle of a spiral wire material 22a.

Description

  The present invention relates to an actuator including a conversion mechanism that converts a rotational motion of a rotational drive source into a linear motion of a moving member.

  For example, there is known an actuator that converts a rotational motion of a motor into a linear motion of a rod by a conversion mechanism and clamps or unclamps a workpiece via the rod. An example of this conversion mechanism is disclosed in Patent Document 1. The feed screw device of Patent Document 1 includes a screw shaft and a moving nut that is screwed onto the screw shaft. The shaft of the screw shaft is connected to a rotational drive source (for example, a servo motor) and is rotatable by transmitting the rotational motion of the rotational drive source. Further, two coil springs are externally fitted to the shaft rod, and both ends of each coil spring are fitted into recesses of a joint member fitted and fixed to both ends of the shaft rod.

  A through passage through which the screw shaft passes is formed inside the moving nut. Two pins are erected on the upper surface of the through passage so as to extend in a direction perpendicular to the length direction of the screw shaft at a predetermined interval in the length direction of the screw shaft. Furthermore, two pins are erected on the lower surface of the through passage so as to extend in a direction orthogonal to the length direction of the screw shaft so as to face each pin erected on the upper surface of the through passage. Each pin is in contact with the wire of each coil spring. And if a coil spring rotates with rotation of a screw shaft, each coil spring will convert rotation motion of a screw shaft into linear motion of a nut for movement, maintaining meshing with each pin. Then, a rod that can be projected and retracted from the actuator body is connected to the moving nut of the feed screw device having the above configuration. Further, the rotation of the rod is restricted by a rotation prevention mechanism.

  When the screw shaft is rotated by the motor, the moving nut and the rod linearly move in a state in which the rotation is restricted by the non-rotating mechanism from the meshing of each pin and each coil spring. When the tip of the rod hits the workpiece, each coil spring is compressed and elastically deformed, and a thrust required to press the rod against the workpiece is applied, so that the workpiece is clamped.

JP 2009-174713 A

  However, in the feed screw device of Patent Document 1, each pin that meshes with each coil spring is erected so as to extend in a direction orthogonal to the length direction of the screw shaft, so that the strand of each coil spring is inclined. It is provided so as to extend in a direction intersecting with each other. For this reason, when the tip of the rod hits the work and the coil spring is compressed, only one of the pins concentrates and presses one part of the wire. For this reason, a part of the coil spring is concentrated and compressed in the direction pressed by the pin, and an unbalanced load is applied to a part of the concentrated and compressed coil spring, causing the coil spring to buckle and buckling. The part is pressed to the shaft bar side. The coil spring is compressed while being in sliding contact with the shaft rod, so that the urging force of the coil spring is difficult to be transmitted to the tip of the rod as a thrust required to press the work, and sufficient for clamping the work. There is a risk that it will not be possible to ensure a sufficient thrust.

  The present invention has been made by paying attention to such problems in the conventional technology, and an object of the present invention is to provide an actuator that can compress a coil spring evenly without buckling. .

  In order to achieve the above object, an invention according to claim 1 is an actuator including a conversion mechanism that converts a rotational motion of a rotational drive source into a linear motion of a moving member, wherein the conversion mechanism is A rotation preventing mechanism that restricts rotation of the member, a rotating member that rotates by the rotational force of the rotation drive source, a coil spring that is attached to the moving member or the rotating member, and a moving member that is attached to the rotating member. A transmitting portion that transmits the rotational motion of the rotating member to the moving member, and the transmitting portion is a gap between adjacent spiral wires in the coil spring, and faces at least in the inclination direction of the spiral wire. The gist is to contact a part of the spiral wire with the same inclination as that of the spiral wire.

  The invention according to claim 2 is the gist of the invention according to claim 1, wherein the transmission portion is a cylindrical pin that is inserted into the gap and tiltable along the inclination of the spiral wire rod. And

  According to a third aspect of the present invention, in the second aspect of the present invention, the pin is supported by a bearing provided on the moving member or the rotating member so as to be rotatable about the central axis of the pin as a rotation center. This is the gist.

The gist of the invention described in claim 4 is that, in the invention described in claim 2 or claim 3, a receiving portion is provided in a portion of the pin that contacts the spiral wire.
The gist of a fifth aspect of the present invention is that, in the first aspect of the present invention, the transmission portion is a transmission coil spring formed at an equal pitch to the helical wire.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the moving member is a cylindrical rod supported by an actuator body so as to be able to appear and retract, and The gist of the coil spring is that it is disposed in the rod.

  According to this invention, the coil spring can be compressed evenly without buckling.

Sectional drawing which shows the electric actuator in 1st Embodiment. FIG. 2 is a sectional view taken along line AA in FIG. 1. BB sectional drawing in FIG. Sectional drawing which shows the state which the front-end | tip of the rod contact | abutted to the workpiece | work. Sectional drawing which shows the state which the motor continues rotating in the state which the front-end | tip of the rod contact | abutted to the workpiece | work. Sectional drawing which shows the electric actuator in 2nd Embodiment. Sectional drawing which shows the state which the front-end | tip of the rod contact | abutted to the workpiece | work. Sectional drawing which shows the state which the motor continues rotating in the state which the front-end | tip of the rod contact | abutted to the workpiece | work. (A) is sectional drawing which shows a part of electric actuator in 3rd Embodiment, (b) is CC sectional view taken on the line in Fig.9 (a). (A) is sectional drawing which shows the state which one end of the press member contact | abutted to the workpiece | work, (b) is sectional drawing which shows the state which the motor continues rotating in the state which one end of the press member contact | abutted to the workpiece | work. Sectional drawing which shows the electric actuator in another embodiment. Sectional drawing which shows the electric actuator in another embodiment. Sectional drawing which shows the electric actuator in another embodiment. Sectional drawing which expands and shows the pin periphery in another embodiment. (A) is sectional drawing which expands and shows the pin periphery in another embodiment, (b) is the DD sectional view taken on the line in Fig.15 (a).

(First embodiment)
A first embodiment in which the present invention is embodied in an electric actuator will be described below with reference to FIGS.

  As shown in FIG. 1, the actuator body 12 of the electric actuator 11 is formed in a cylindrical shape having openings on both sides. A slide bearing 13 is fixed to one end (left end in FIG. 1) of the actuator body 12, and a motor 14 as a rotational drive source is fixed to the other end (right end in FIG. 1). A rotation shaft 14 a of the motor 14 is located in the actuator body 12. A columnar shaft member 15 as a rotating member is connected to the tip of the rotating shaft 14a. The shaft member 15 extends along the axial direction of the actuator body 12, and the tip of the shaft member 15 is located inside the slide bearing 13. The shaft member 15 can rotate integrally with a rotating shaft 14 a that rotates by driving the motor 14.

  In the actuator body 12, a rod 21 is provided as a moving member that extends along the axial direction and has a cylindrical shape whose outer end opening is closed by a cap 20. The rod 21 is pierced and supported by the actuator body 12 through the slide bearing 13 so as to be able to appear and retract. A coil spring 22 is disposed inside the rod 21 so as to extend along the axial direction of the actuator body 12. In a state before the coil spring 22 is compressed, the spiral wire 22a of the coil spring 22 is inclined at an inclination angle θ1. One end of the coil spring 22 is fixed to the inner end surface of the cap 20, and the other end is in contact with the base end of the shaft member 15.

  As shown in FIGS. 2 and 3, a pair of extending portions 15 a extending along the axial direction of the shaft member 15 is provided at the tip of the shaft member 15. The outer peripheral surface of each extending portion 15 a is located on the same peripheral surface as the outer peripheral surface of the shaft member 15. A space S is formed between the pair of extending portions 15a. As shown in FIG. 3, each extending portion 15 a is formed with an insertion hole 15 b extending in a direction orthogonal to the axial direction of the shaft member 15 and communicating with the space S. Each insertion hole 15b has a circular hole shape and is provided at a position facing each other.

  A round bar-like support member 23 is inserted into each insertion hole 15b. A part of each support member 23 protrudes into the space S and is rotatable about the central axis of the support member 23 in each insertion hole 15b. A cylindrical bearing 24 is disposed in the space S. On the outer peripheral surface of the bearing 24, a pair of fitting recesses 24 a that are recessed toward the axis of the bearing 24 are formed at positions facing each other. And the bearing 24 is supported by each support member 23 because the site | part which protruded in the space S in each support member 23 is fitted by each fitting recessed part 24a. Further, a reservoir portion 24 b for storing a lubricant is formed on the inner peripheral surface of the bearing 24.

  As shown in an enlarged view in FIG. 1, two cylindrical pins 25 and 26 are supported on the inner side of the bearing 24 so as to be rotatable about the central axis L1. The space between each pin 25, 26 and the bearing 24 is lubricated by a lubricant filled in the reservoir 24b. The tips of the pins 25 and 26 are arranged at positions where the pins 25 and 26 are inserted into the gaps 22c between the adjacent spiral wires 22a of the coil spring 22 and are opposed to each other in the inclination direction of the spiral wire 22a by the gap 22c. It protrudes from the inside of the spring 22. In addition, receiving portions 25 a and 26 a that are recessed in an arc shape are formed at the tip portions of the pins 25 and 26 over the entire circumferential direction of the pins 25 and 26. Inside the bearing 24, a gap is provided between the base ends of the pins 25 and 26.

  Each of the pins 25 and 26 and the bearing 24 can swing in the space S as each support member 23 rotates about its central axis. That is, each pin 25, 26 can be tilted along the inclination of the spiral wire 22a when contacting each part of the spiral wire 22a facing each other in the inclination direction of the spiral wire 22a in the gap 22c between the adjacent spiral wires 22a. It has become. The pins 25 and 26 are prevented from coming off from the bearing 24 by the helical wire 22a being fitted into the receiving portions 25a and 26a.

Next, the rotation preventing mechanism will be described.
As shown in FIG. 2, the inner surface of the plain bearing 13 is formed in a flat surface shape and connects the pair of first guide portions 13a facing each other and the edges of the first guide portions 13a to the outside. The second guide portion 13b is formed in an arc shape so as to swell toward the surface. Further, the outer surface of the rod 21 connects the pair of first guided portions 21a guided by the pair of first guide portions 13a of the slide bearing 13 and the edges of the respective first guided portions 21a and slide bearings. It comprises an arc-shaped second guided portion 21b guided by thirteen second guiding portions 13b.

  When the shaft 25 rotates and the pins 25 and 26 rotate in the rod 21, the coil spring 22 meshing with the pins 25 and 26 tries to rotate, and the cap 20 is fixed to one end of the coil spring 22. The rod 21 tries to rotate via However, since the pair of first guided portions 21 a is in contact with the pair of first guide portions 13 a of the slide bearing 13, the coil spring 22 and the rod 21 rotate together with the rotation of the shaft member 15. This has been prevented. Therefore, in this embodiment, the pair of first guided portions 21 a of the rod 21 and the pair of first guide portions 13 a of the slide bearing 13 constitute a rotation preventing mechanism.

  When the rotational movement of the shaft member 15 is transmitted to the coil spring 22 via the pins 25 and 26, the pair of first guided portions 21 a is in sliding contact with the pair of first guide portions 13 a of the slide bearing 13. The second guided portion 21b of the rod 21 is guided while being in sliding contact with the second guide portion 13b of the slide bearing 13. Thereby, the coil spring 22 and the rod 21 are linearly moved. Therefore, in this embodiment, the shaft member 15, the coil spring 22, the pins 25 and 26, and the slide bearing 13 constitute a conversion mechanism that converts the rotational motion of the motor 14 into the linear motion of the rod 21. 26 functions as a transmission unit that transmits the rotational motion of the shaft member 15 to the coil spring 22 and the rod 21.

  Further, when the motor 14 is rotated in the forward direction, as shown in FIG. 4, the rod 21 is projected from the actuator body 12 and is disposed at a clamping position for clamping the workpiece W. On the contrary, when the motor 14 is rotated in the reverse direction, the rod 21 is immersed in the actuator body 12 as shown in FIG. 1 and is disposed at the unclamping position.

Next, the operation of the electric actuator 11 having the above configuration will be described.
As shown in FIG. 1, when the motor 14 is driven in the forward direction (the direction of the arrow M <b> 1 shown in FIG. 1) by energizing the motor 14 with the rod 21 being immersed, the rotation shaft 14 a rotates. Accordingly, the shaft member 15 rotates, and the pins 25 and 26 rotate in the positive direction within the rod 21. Then, the pin 25 rotates in the direction of the arrow R1 with the central axis L1 of the pin 25 as the center of rotation while being in sliding contact with the receiving portion 25a and the spiral wire 22a in surface contact. On the other hand, the pin 26 rotates in the direction of the arrow R2 with the central axis L1 of the pin 26 as the center of rotation while being in sliding contact with the receiving portion 26a and the spiral wire 22a in surface contact. That is, the pins 25 and 26 rotate in different directions with the central axis L1 as the rotation center. Then, the coil spring 22 and the rod 21 are linearly moved along the axial direction of the actuator body 12 in the protruding direction of the rod 21 (the direction of the arrow Y1 shown in FIG. 1), and as shown in FIG. The tip (outer end surface of the cap 20) hits the workpiece W, and the movement of the rod 21 is restricted.

  Furthermore, the motor 14 continues to rotate until the thrust applied to the rod 21 reaches a necessary and sufficient value. At this time, as shown in FIG. 5, the coil spring 22 is sent toward the tip end side of the rod 21 by the rotation of the pins 25, 26. This portion is compressed, and the inclination of the coil spring 22 becomes an inclination angle θ2 smaller than the inclination angle θ1. Accordingly, as shown in an enlarged view in FIG. 5, the pins 25 and 26 are tilted along the inclination angle θ2 of the spiral wire 22a, and the urging force of the spiral wire 22a is received by the receiving portions 25a and 26a. . As a result, the coil spring 22 is evenly compressed toward the distal end side of the rod 21, and the thrust applied to the rod 21 is increased.

  Then, when the thrust applied to the rod 21 reaches a necessary and sufficient value, the energization to the motor 14 is interrupted. Therefore, in a state where the driving of the motor 14 is stopped, the thrust is always applied to the distal end side of the rod 21, and the thrust necessary to press the rod 21 against the workpiece W is ensured.

In the above embodiment, the following effects can be obtained.
(1) The electric actuator 11 includes a conversion mechanism that converts the rotational motion of the motor 14 into the linear motion of the rod 21. This conversion mechanism includes a shaft member 15 connected to the rotating shaft 14a of the motor 14, a coil spring 22 disposed inside the rod 21, and a shaft member 15 supported by the shaft member 15 and rotating motion of the shaft member 15 as a coil spring. 22 and pins 25 and 26 that transmit to the rod 21. Then, as the shaft member 15 rotates, the pins 25 and 26 rotate, and when the coil spring 22 is compressed, the pins 25 and 26 are tilted along the inclination of the spiral wire 22a. Therefore, when the coil spring 22 is compressed, the pins 25 and 26 are tilted, so that the gap 22c between the adjacent spiral wires 22a in the coil spring 22 is changed in the direction of the spiral wire 22a. Each part can be pressed by pins 25 and 26. For this reason, the coil spring 22 can be uniformly compressed toward the tip end side of the rod 21 by the pins 25 and 26.

  (2) In this embodiment, cylindrical pins 25 and 26 are inserted into the gap 22c. Then, the rotational movement of the shaft member 15 is transmitted to the coil spring 22 via the pins 25 and 26, whereby the coil spring 22 and the rod 21 can be linearly moved. Therefore, the pins 25 and 26 can function as a transmission unit simply by inserting the pins 25 and 26 into the gap 22c.

  (3) The pins 25 and 26 are rotatable about the central axis of the pins 25 and 26 by the bearing 24 provided at the tip of the shaft member 15. Therefore, when the coil spring 22 and the rod 21 are linearly moved along the axial direction of the actuator body 12 while the pins 25 and 26 are in contact with the spiral wire 22a, the pins 25 and 26 have their center axis L1. Can be rotated around the center of rotation. According to this, the frictional resistance between the pins 25 and 26 and the spiral wire 22a can be reduced, and the coil spring 22 can be smoothly fed to the distal end side of the rod 21 to clamp the workpiece W. This thrust can be easily applied to the rod 21.

  (4) Receiving portions 25a and 26a that are recessed in an arc shape are formed over the entire circumferential direction of the pins 25 and 26 at portions of the pins 25 and 26 that contact the spiral wire 22a. Therefore, since the spiral wire 22a and the receiving portions 25a and 26a are in surface contact, the receiving portions 25a and 26a are not formed at the tip portions of the pins 25 and 26, and the spiral wire 22a and the pins 25 and 26 The contact area between the spiral wire 22a and the pins 25 and 26 can be increased as compared with the case where the point contact is a point contact. As a result, it is possible to suppress wear at the contact portion between the spiral wire 22a and the pins 25 and 26.

  (5) The coil spring 22 is disposed in the rod 21. Therefore, unlike the case where the coil spring 22 is arranged on the outer peripheral side of the rod 21, it is not necessary to secure a space for arranging the coil spring 22 on the outer peripheral side of the rod 21, so that the electric actuator 11 itself is made compact. be able to.

  (6) Receiving portions 25a and 26a that are recessed in an arc shape are formed at the tip portions of the pins 25 and 26. Therefore, it is possible to prevent the pins 25 and 26 from coming out of the bearing 24 by fitting and locking the spiral wire 22a into the receiving portions 25a and 26a.

  (7) In this embodiment, two cylindrical pins 25 and 26 are inserted inside the bearing 24, and each pin 25 and 26 is supported rotatably about its center axis L1. Therefore, the pin 25 rotates in the direction of the arrow R1 with the central axis L1 of the pin 25 as the rotation center while being in sliding contact with the receiving portion 25a and the spiral wire 22a in surface contact. On the other hand, the pin 26 rotates in the direction of the arrow R2 with the central axis L1 of the pin 26 as the center of rotation while being in sliding contact with the receiving portion 26a and the spiral wire 22a in surface contact. That is, the pins 25 and 26 rotate in different directions with the central axis L1 as the rotation center. Therefore, it is possible to suppress wear at the contact portion between the spiral wire 22a and the pins 25 and 26.

(Second Embodiment)
Hereinafter, a second embodiment in which the present invention is embodied in an electric actuator will be described with reference to FIGS. In the embodiment described below, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the redundant description thereof is omitted or simplified.

  As shown in FIG. 6, the electric actuator 31 is provided with a transmission coil spring 32 as a transmission portion on the outer peripheral side of the shaft member 15. The transmission coil spring 32 has the same pitch as the coil spring 22, and the wire diameter of the spiral wire 32 a of the transmission coil spring 32 is the same as the wire diameter of the spiral wire 22 a of the coil spring 22. A spring guide 33 is recessed at the base end of the shaft member 15. One end (motor 14 side) of the transmission coil spring 32 is fitted to the spring guide 33, and the other end (opposite side to the motor 14) is positioned closer to the distal end side of the rod 21 than the distal end of the shaft member 15. Yes. The transmission coil spring 32 is disposed inside the rod 21, and the coil spring 22 and the transmission coil spring 32 are partially engaged with each other. In a state where the coil spring 22 and the transmission coil spring 32 are engaged with each other, the inclination of the coil spring 22 and the transmission coil spring 32 is the same inclination angle θ3.

  In the electric actuator 31 having the above-described configuration, when the motor 14 is driven in the forward direction (the direction of the arrow M2 shown in FIG. 6) by energizing the motor 14 with the rod 21 being immersed, the rotation of the rotating shaft 14a. As a result, the shaft member 15 rotates and the transmission coil spring 32 rotates in the positive direction within the rod 21. Then, the coil spring 22 and the rod 21 are linearly projected along the axial direction of the actuator body 12 by the meshing of the helical wire 32a of the transmission coil spring 32 and the helical wire 22a of the coil spring 22 (FIG. 6). And the tip of the rod 21 (the outer end surface of the cap 20) abuts against the workpiece W, as shown in FIG. When the tip of the rod 21 hits the workpiece W, the movement of the rod 21 is restricted.

  Furthermore, the motor 14 continues to rotate until the thrust applied to the rod 21 reaches a necessary and sufficient value. At this time, as shown in FIG. 8, from the portion of the coil spring 22 on the tip side of the rod 21 relative to the portion meshing with the transmission coil spring 32 and the portion of the transmission coil spring 32 meshing with the coil spring 22. Also, the part on the motor 14 side is compressed. Then, the inclination of the portion on the tip end side of the rod 21 with respect to the portion engaging with the transmission coil spring 32 in the coil spring 22 and the portion on the motor 14 side with respect to the portion engaging with the coil spring 22 in the transmission coil spring 32. Is an inclination angle θ4 smaller than the inclination angle θ3. Thus, the portion of the coil spring 22 closer to the tip of the rod 21 than the portion meshed with the transmission coil spring 32 and the portion of the transmission coil spring 32 closer to the motor 14 than the portion meshed with the coil spring 22 are located. Since the compression is performed uniformly, the thrust applied to the rod 21 increases.

  Then, when the thrust applied to the rod 21 reaches a necessary and sufficient value, the energization to the motor 14 is interrupted. Therefore, in a state where the driving of the motor 14 is stopped, the thrust is always applied to the distal end side of the rod 21, and the thrust necessary to press the rod 21 against the workpiece W is ensured.

Therefore, according to the second embodiment, the following effects can be obtained.
(8) The electric actuator 31 is provided with a transmission coil spring 32 having the same pitch as the coil spring 22 on the outer peripheral side of the shaft member 15. Therefore, the coil spring 22 can be evenly compressed toward the distal end side of the rod 21 by the transmission coil spring 32 simply by disposing the transmission coil spring 32 on the outer peripheral side of the shaft member 15.

(Third embodiment)
A third embodiment in which the present invention is embodied in an electric actuator will be described below with reference to FIGS. The electric actuator 41 of the third embodiment is different from the one that clamps the workpiece W by pressing the tip of the rod 21 against the workpiece W as in the first and second embodiments. The workpiece W is clamped by linearly moving the conveyor table T provided to the workpiece and pressing one end of the pressing member F provided on the upper surface of the conveyor table T against the workpiece W.

  As shown in FIG. 9A, the electric actuator 41 is provided with a coil spring 22 on the outer peripheral side of the shaft member 15. One end (the motor 14 side) of the coil spring 22 is fitted into the spring guide 33, and the other end (the side opposite to the motor 14) is in a free state.

  As shown in FIG. 9B, an insertion hole 42 a extending along the axial direction of the actuator body 42 is formed on the upper surface of the actuator body 42. Further, a guide rail 47 extending along the axial direction of the actuator body 42 is provided on the upper surface of the actuator body 42. On the lower surface of the transport table T, a linear guide 48 that can be engaged with the guide rail 47 is provided. A plurality of ball bearings 49 are provided between the guide rail 47 and the linear guide 48. The plurality of ball bearings 49 allow the linear guide 48 to move smoothly in the axial direction of the actuator body 42 with respect to the guide rail 47.

  A connection member 43 is provided on the lower surface of the transfer table T so as to extend into the actuator body 42 through the insertion hole 42a. One end of the connecting member 43 is connected to the transport table T, and the other end extends to a position where it overlaps with the shaft member 15. A circular through hole 43a is formed at the other end of the connecting member 43, and a round bar-shaped support shaft 44 is inserted through the through hole 43a via a bearing 43b. The support shaft 44 is supported by the bearing 43 b so as to be rotatable about the center axis thereof and is provided so as to extend toward the shaft member 15.

  A moving member 45 is coupled to a portion of the support shaft 44 on the shaft member 15 side, and the moving member 45 can swing when the support shaft 44 rotates about its central axis. The moving member 45 has a pair of extending portions 45a extending up to a position where the shaft member 15 is sandwiched from above and below, and through holes 45b are formed in portions facing each extending portion 45a. Pins 46a and 46b are inserted through the through holes 45b via bearings 45c. Each pin 46a, 46b is supported by a bearing 45c so as to be rotatable about its central axis L2. The ends of the pins 46a and 46b on the shaft member 15 side are inserted into the gaps 22c between the adjacent spiral wire members 22a of the coil spring 22, and are located in positions facing each other in the inclination direction of the spiral wire member 22a within the gap 22c. It protrudes from the outside of the coil spring 22.

  As the shaft member 15 rotates, the coil spring 22 rotates. Then, the moving member 45 tries to rotate due to the engagement between the pins 46a and 46b and the coil spring 22, but a part of the connecting member 43 connected to the moving member 45 is located in the insertion hole 42a, and Since the guide rail 47 is engaged with the linear guide 48, it is possible to prevent the moving member 45 and the connecting member 43 from rotating together with the rotation of the shaft member 15. Therefore, in the present embodiment, the insertion hole 42a, the connecting member 43, the guide rail 47, and the linear guide 48 constitute a rotation preventing mechanism.

  When the rotational movement of the shaft member 15 is transmitted to the moving member 45 through the pins 46a and 46b, the connecting member 43 is guided to the insertion hole 42a and the linear guide 48 is guided to the guide rail 47. The moving member 45, the connecting member 43, and the transport table T are configured to move linearly. Therefore, in this embodiment, the shaft member 15, the coil spring 22, the pins 46 a and 46 b, and the anti-rotation mechanism constitute a conversion mechanism, and the pins 46 a and 46 b change the rotational movement of the shaft member 15 with the moving member 45, It functions as a transmission unit that transmits the connection member 43 and the transfer table T.

  When the motor 14 is rotated in the forward direction, the transfer table T is disposed at a clamping position for clamping the workpiece W, while when the motor 14 is rotated in the reverse direction, the transfer table T is at the unclamping position. Be placed.

  In the electric actuator 41 having the above configuration, when the motor 14 is driven in the forward direction (the direction of the arrow M3 shown in FIG. 9A) by energizing the motor 14, the shaft member 15 rotates with the rotation of the rotating shaft 14a. Then, the coil spring 22 rotates in the positive direction. Then, due to the meshing of the helical wire 22a and the pins 46a and 46b, the moving member 45 and the connecting member 43 are linearly along the axial direction of the actuator body 42 in the direction opposite to the motor 14 side (FIG. 9 (a ) (In the direction of arrow Y3). The pin 46a rotates in the direction of the arrow R3 with the central axis L2 of the pin 46a as the center of rotation while being in sliding contact with the spiral wire 22a as the coil spring 22 rotates. On the other hand, as the coil spring 22 rotates, the pin 46b rotates in the direction of the arrow R4 with the central axis L2 of the pin 46b as the center of rotation while being in sliding contact with the spiral wire 22a. That is, the pins 46a and 46b rotate in different directions with the central axis L2 as the rotation center. And as shown to Fig.10 (a), the end of the press member F bumps into the workpiece | work W, and the movement of the conveyance table T is controlled.

  Further, the motor 14 continues to rotate until the thrust applied to the transfer table T reaches a necessary and sufficient value. At this time, as shown in FIG. 10 (b), the rotation of the coil spring 22 compresses the portion of the coil spring 22 closer to the motor 14 than the portion where the pins 46a and 46b are engaged with each other. It will be done. At this time, the pins 46 a and 46 b are tilted along the inclination of the spiral wire 22 a as the moving member 45 swings. As a result, the coil springs 22 are evenly compressed, and the thrust applied to the transfer table T increases.

  When the thrust applied to the transfer table T reaches a necessary and sufficient value, the energization to the motor 14 is interrupted. Therefore, in a state where the driving of the motor 14 is stopped, the thrust is always applied to the transfer table T, and the thrust necessary to press the pressing member F against the workpiece W is secured.

Therefore, according to the third embodiment, the following effects can be obtained in addition to the effects (1) to (4), (6), and (7) of the first embodiment. .
(9) The electric actuator 41 of the third embodiment clamps the workpiece W by linearly moving the transfer table T provided on the upper surface of the actuator body 42 and pressing one end of the pressing member F against the workpiece W. is there. Therefore, the length of the actuator main body 42 along the axial direction can be shortened, which is effective when there is no space in the axial direction of the actuator main body 42.

In addition, you may change the said embodiment as follows.
In 2nd Embodiment, as shown in FIG. 11, the coil spring 22 may be arrange | positioned at the outer peripheral side of the rod 21. As shown in FIG. One end (the side opposite to the motor 14) of the coil spring 22 is fixed to the outer peripheral surface of the rod 21, and the other end (the motor 14 side) is in a free state. Further, a part of the transmission coil spring 32 is located on the outer peripheral side of the rod 21 and is engaged with the coil spring 22.

  As shown in FIG. 12, the wire diameter of the spiral wire 22 a of the coil spring 22 may be larger than the wire diameter of the spiral wire 32 a of the transmission coil spring 32. According to this, the durability of the coil spring 22 can be improved. Further, by appropriately adjusting the wire diameter of the helical wire 22a of the coil spring 22, the spring constant can be changed as appropriate, and the thrust required to press the rod 21 against the workpiece W can be adjusted to a desired thrust. it can.

  In the second embodiment, the diameter of the spiral wire 22a of the coil spring 22 and the diameter of the spiral wire 32a of the transmission coil spring 32 may be reduced. According to this, the diameter of the rod 21 can be reduced, and accordingly, the length along the direction orthogonal to the axial direction of the actuator body 12 can be shortened. Therefore, the electric actuator 31 itself can be made compact in a direction orthogonal to the axial direction of the actuator body 12.

  As shown in FIG. 13, the wire diameter of the helical wire 22a of the coil spring 22 and the wire diameter of the helical wire 32a of the transmission coil spring 32 are the same, and the diameter of the coil spring 22 is the transmission coil spring 32. It may be smaller than the diameter. In this case, as shown in an enlarged view in FIG. 13, the outer peripheral portion 22 b of the helical wire 22 a of the coil spring 22 needs to abut on the inner peripheral portion 32 b of the helical wire 32 a of the transmission coil spring 32. . The coil spring 22 and the transmission coil spring 32 are brought into contact with each other by the contact between the outer peripheral portion 22b of the helical wire 22a of the coil spring 22 and the inner peripheral portion 32b of the spiral wire 32a of the transmission coil spring 32. They are engaged. According to this, compared with the case where the coil spring 22 and the transmission coil spring 32 are meshed with the same diameter, the pitch of the coil spring 22 and the transmission coil spring 32 can be reduced. In order to increase the thrust required to press the rod 21 against the workpiece W, it is necessary to reduce the amount of movement of the rod 21 per rotation of the motor 14. For this purpose, since the pitch of the coil springs 22 needs to be reduced, the thrust necessary to press the rod 21 against the workpiece W can be increased by applying this embodiment.

  In the first embodiment, one pin 50 may be inserted inside the bearing 24 as shown in FIG. The length of the pin 50 is longer than the diameter of the shaft member 15. Both ends of the pin 50 are protruded from the inside of the coil spring 22 at positions facing each other in the inclination direction of the spiral wire 22 a with a gap 22 c between adjacent spiral wires 22 a of the coil spring 22. Receiving portions 50 a that are recessed in an arc shape are formed at both ends of the pin 50 over the entire circumferential direction of the pin 50. The pin 50 is prevented from coming off from the bearing 24 by a retaining ring 55.

  According to this, compared with the case where the pins 50 are protruded from the inside or the outside of the coil spring 22 at positions facing each other in the inclination direction of the spiral wire 22a with the gap 22c, only one pin 50 is used. Thus, since the pin 50 can be protruded at the gap 22c in a position facing the spiral wire 22a in the inclination direction, the number of parts can be reduced.

  In the first embodiment, the bearing 24 may be omitted, and the pins 25 and 26 may be configured so as not to rotate around the central axis L1. For example, as shown in FIG. 15A, one pin 50 is inserted into the gap 22c. The pin 50 is formed with a circular through hole 51 penetrating along a direction orthogonal to the axial direction, and a round bar-like support shaft 52 is inserted into the through hole 51. As shown in FIG. 15B, both ends of the support shaft 52 are inserted into the respective insertion holes 15b, and the support shaft 52 is rotatable about its center axis. According to this, the pin 52 can be swung in the space S by the support shaft 52 rotating about the center axis thereof, and when the pin 50 comes into contact with the spiral wire 22a, the spiral wire rod The pin 50 can be tilted along the inclination of 22a.

In the first embodiment, the receiving portions 25a and 26a may be deleted.
In the first and second embodiments, when the motor 14 is rotated in the forward direction, the rod 21 is immersed in the actuator body 12 and disposed at the unclamping position. When rotated in the direction, the rod 21 may protrude from the actuator body 12 and be disposed at a clamping position for clamping the workpiece W.

  In the third embodiment, when the motor 14 is rotated in the forward direction, the transfer table T is disposed at the unclamping position, while when the motor 14 is rotated in the reverse direction, the transfer table T is moved to the workpiece W. You may make it arrange | position in the clamp position which clamps.

  In the first and second embodiments, the workpiece W is clamped by pressing the tip of the rod 21 against the workpiece W. However, the present invention is not limited to this, and for example, a transfer table T or a hand member is connected to the tip of the rod 21. The workpiece W may be clamped by pressing the workpiece W against one end of the transfer table T or the hand member.

In each of the above embodiments, an air motor, an internal combustion engine, or the like may be applied as a rotational drive source in addition to the motor 14.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.

  (B) The two pins are inserted into the gap, and the tip of each pin protrudes from the inside at a position facing the gap in the inclined direction of the spiral wire rod. The actuator according to any one of claims 2 to 4.

  T: Transport table as a moving member, 11, 31, 41 ... Electric actuator, 12, 42 ... Actuator body, 13 ... Slide bearing constituting part of conversion mechanism, 13a ... First constituting part of anti-rotation mechanism DESCRIPTION OF SYMBOLS 1 Guide part, 14 ... Motor as a rotational drive source, 15 ... Shaft member as a rotating member constituting a part of the conversion mechanism, 21 ... Rod as a moving member, 21a ... A first constituting a part of the rotation preventing mechanism 1 guided portion, 22 ... coil spring constituting a part of the conversion mechanism, 22a ... spiral wire, 22c ... gap, 24 ... bearings, 25, 26, 46a, 46b, 50 ... transmission constituting a part of the conversion mechanism Pins that function as parts, 25a, 26a, 50a ... receiving parts, 32 ... coil springs for transmission as transmission parts, 32a ... spiral wires, 42a ... insertion holes that constitute part of the detent mechanism, 43 Coupling member constituting a part of a detent mechanism, 45 ... moving member, the guide rails forming part of 47 ... detent mechanism, a linear guide which constitutes a part of a 48 ... detent mechanism.

Claims (6)

An actuator having a conversion mechanism for converting the rotational motion of the rotational drive source into the linear motion of the moving member,
The conversion mechanism includes a rotation prevention mechanism that restricts rotation of the moving member;
A rotating member that is rotated by the rotational force of the rotational drive source;
A coil spring attached to the moving member or the rotating member;
A transmission unit that is attached to the moving member or the rotating member and transmits a rotational motion of the rotating member to the moving member;
The transmitting portion is a gap between adjacent spiral wires in the coil spring and abuts at least a part of the spiral wire facing in the inclination direction of the spiral wire with the same inclination as the inclination of the spiral wire. Actuator.   2. The actuator according to claim 1, wherein the transmission unit is a cylindrical pin that is inserted into the gap and can be tilted along the inclination of the spiral wire.   3. The actuator according to claim 2, wherein the pin is supported by a bearing provided on the moving member or the rotating member so as to be rotatable about a central axis of the pin as a rotation center.   The actuator according to claim 2 or 3, wherein a receiving portion is provided at a portion of the pin that contacts the spiral wire.   The actuator according to claim 1, wherein the transmission unit is a transmission coil spring formed at an equal pitch to the spiral wire.   6. The moving member according to claim 1, wherein the moving member is a cylindrical rod supported by an actuator body so as to be able to appear and retract, and the coil spring is disposed in the rod. The actuator according to one item.

Images