JP2007092967A - Electrically operated actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrically operated actuator which can surely and stably restrict the displacement of a piston at the stroke end, and also can reduce its size, and can improve its durability. <P>SOLUTION: The electrically operated actuator comprises a gear mechanism 54 for changing the driving speed from a driving section 52, and a converting mechanism 56 for converting the rotational displacement changed in its speed by the gear mechanism 54 into the linear displacement, wherein a plurality of satellite gears 68 in the gear mechanism 54 are rotatably supported by a gear holder 74. The electrically operated actuator ascends and descends along the elevating rail 92 of a cam body 84 via a roller 104 because the gear holder 74 is turned via the satellite gears 68. A piston 58 connected to the gear holder 74 is moved in the axial direction of a body 60, and as a result, the gripped state of a workpiece W can be changed by opening and closing a pair of chucks 136a, 136b engaged with the end portion of the piston 58. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric actuator capable of displacing a piston along an axial direction under a driving action of a driving unit and transporting and gripping a workpiece under the displacement action of the piston.

  Conventionally, as an example to which such an electric actuator is applied, a chuck device that is attached to a tip portion of a machine tool or the like and can grip a workpiece by opening and closing a gripping mechanism is known.

  As shown in FIG. 10, the chuck device 1 is provided with a motor 3 inside a casing 2, and a cam 5 having an elliptical cross section is connected to an upper end portion of an output shaft 4 of the motor 3. A pair of rollers 6 a and 6 b abut on the outer peripheral surface of the cam 5, and the rollers 6 a and 6 b are supported at one end of a pair of fingers 7 a and 7 b that are pivotally supported with respect to the casing 2. Each is provided rotatably. The fingers 7a and 7b are provided with coil springs 8 that pull one end of the fingers 7a and 7b toward each other, and the rollers 6a and 6b attached to the one end are always pressed toward the outer peripheral surface of the cam 5. ing. The fingers 7a and 7b are respectively provided with spring plates 9a and 9b between a portion pivotally supported by the casing 2 and one end, and the spring plates 9a and 9b are portions where the fingers 7a and 7b are pivotally supported. Can be bent outward from the cam 5 with the fulcrum as a fulcrum. Further, claw portions 11a and 11b capable of gripping the object to be clamped 10 are provided at the other ends of the fingers 7a and 7b, respectively.

  Then, the cam 5 rotates under the driving action of the motor 3, and the rollers 5 a and 6 b are displaced radially outward so as to overcome the spring force of the coil spring 8 and be separated from each other by the cam 5. Tilts with the part pivotally supported with respect to the casing 2 as a fulcrum. Thereby, a pair of nail | claw part 11a, 11b is displaced to the direction which mutually approaches, and the to-be-clamped object 10 is hold | gripped by this nail | claw part 11. FIG. At this time, the gripping force of the object 10 to be clamped by the claw portions 11a and 11b is held by the spring force of the spring plates 9a and 9b (see, for example, Patent Document 1).

JP-A-5-220684

  By the way, in the prior art which concerns on patent document 1, since it has the structure which connects the cam 5 directly with respect to the motor 3 which is a drive source, the output output from this motor 3 is transmitted to the said cam 5 as it is, There is a problem that the cam 5 cannot be controlled to a desired rotation amount (rotation speed, rotation angle, etc.).

  Further, the amount of tilting of the fingers 7a and 7b is controlled based on the number of rotations detected by the optical sensor 12 provided in the motor 3, but the optical sensor 12 is expensive, so the chuck device 1 The manufacturing cost is increased and the size of the chuck device 1 is increased, and there is no means for mechanically stopping the tilting operation of the fingers 7a and 7b and the rotating operation of the cam 5, so that the motor 3 is In the case of excessive rotation due to the cause, it is difficult to reliably and stably hold the object to be clamped 10 by the fingers 7a and 7b.

  Further, when the object to be clamped 10 is gripped while the fingers 7a and 7b are tilted, the spring force of the coil spring 8 interposed between the fingers 7a and 7b and the spring force of the leaf spring 9 act in opposite directions. Therefore, there is a concern that the spring force of the coil spring 8 and the leaf spring 9 cancel each other, and the gripping force of the object 10 held by the spring force of the leaf spring 9 is reduced. .

  The present invention has been made in consideration of the above-mentioned various problems, and can control the output from the drive unit transmitted to the piston via the gear mechanism, and can also be used for the piston at the displacement end position. An object of the present invention is to provide an electric actuator capable of reliably and stably regulating displacement, and capable of reducing the size of the apparatus and improving its durability.

To achieve the above object, the present invention comprises a body,
A drive unit coupled to the body and rotationally driven under energization;
A gear mechanism having a first gear coupled to the driving unit and rotationally driven, and a second gear revolving around the first gear;
A rotating member that rotatably supports the second gear and that is rotationally displaced about the axis of the body under the rotating action of the second gear;
A displacement mechanism for displacing the rotating member along the axial direction of the body under the rotating action of the rotating member;
A piston coupled to the rotating member and provided to be displaceable along an axial direction of the body;
A spring having a resilient force to press the piston toward one side in the axial direction;
It is characterized by providing.

  According to the present invention, by transmitting the driving force from the driving unit via the first and second gears of the gear mechanism, the rotational speed can be changed by a predetermined amount and the driving force can be increased, The rotating member to which the driving force is transmitted can be displaced in the axial direction of the body by a displacement mechanism. Therefore, by transmitting the driving force to the piston through the gear mechanism, the driving force can be controlled to a desired amount, and the function of shifting and increasing the driving force and the rotation through the driving force can be controlled. By having the function of displacing the member along the axial direction, the electric actuator can be reduced in size.

  Further, when the rotating member is displaced in the axial direction via the displacement mechanism, the second gear supported by the rotating member is displaced in the axial direction while rotating in a state of being engaged with the first gear. Therefore, the wear at the time of meshing between the first gear and the second gear is suitably suppressed, and the durability of the gear mechanism can be improved.

  Furthermore, since the piston is pressed to one side in the axial direction by the elastic force of the spring, the displacement of the piston can be reliably and stably regulated at one displacement end position. On the other hand, the rotating member is displaced in the axial direction via the displacement mechanism, thereby displacing the piston to the other side in the axial direction against the elastic force of the spring. As a result, even when the drive unit is not driven, it is possible to reliably and stably hold the piston at the displacement end position by the elastic force of the spring.

In addition, the displacement mechanism is provided on the rotating member, and is a roller that is rotatably supported via a support shaft that is substantially orthogonal to the axis of the rotating member.
A guide portion that is formed at a position facing the roller when the rotating member rotates, and that changes in height along the axial direction of the rotating member;
The roller may be rotated along the guide portion under the rotating action of the rotating member, and the elastic force of the spring may be biased in a direction in which the roller is pressed toward the guide portion side via the piston.

  As a result, the roller is displaced along the guide portion under the rotating action of the rotating member, so that the roller is gradually displaced in the direction opposite to the biasing direction of the spring's elastic force by the guide portion whose height dimension changes. Accordingly, the rotating member on which the roller is supported can be displaced along the axial direction. As a result, the piston connected to the rotating member can be displaced along the axial direction of the body against the spring force of the spring.

  Furthermore, by providing the rotating member with a stopper that restricts the rotational displacement of the rotating member by engaging with the body, for example, the rotating member rotates excessively under the driving action of the drive unit. The rotational displacement can be stopped reliably and simply. As a result, the detection mechanism conventionally provided for detecting and controlling the amount of rotation of the drive unit is not required, so that the electric actuator can be reduced in size and cost.

  Furthermore, by making the electric actuator a gripping device including a pair of chucks that can grip a workpiece by opening and closing under the displacement action of the piston, the chuck is interlocked and opened and closed under the displacement action of the piston. The workpiece can be gripped under the action, and the gripping state of the workpiece by the chuck can be suitably maintained by the elastic force of the spring.

  According to the present invention, the following effects can be obtained.

  That is, by providing a gear mechanism that shifts and increases the driving force from the driving unit, the driving force transmitted to the piston can be controlled to a desired amount, and the function of shifting and increasing the driving force; Since the rotation member is also displaced in the axial direction via the driving force, the electric actuator can be reduced in size. In addition, by rotating in the axial direction while rotating in a state where the second gear is engaged with the first gear in the gear mechanism, wear during the engagement of the gear mechanism is suppressed. Can be improved.

  Furthermore, since the piston is pressed to one side in the axial direction by the elastic force of the spring, the displacement of the piston at the displacement end position can be reliably and stably regulated.

  Preferred embodiments of the electric actuator according to the present invention will be described below and described in detail with reference to the accompanying drawings.

  In FIG. 1, reference numeral 50 indicates a workpiece gripping chuck which is an example of the electric actuator according to the first embodiment of the present invention.

  As shown in FIG. 1, the workpiece gripping chuck 50 includes a driving unit 52 that is rotationally driven when supplied with an electric current, and a driving force that is connected to the driving unit 52 and output from the driving unit 52. A gear mechanism 54 that changes the rotational speed, a conversion mechanism 56 that is connected to the gear mechanism 54 and converts the rotational driving force output via the gear mechanism 54 into linear motion, the gear mechanism 54, and the conversion mechanism 56, a body 60 having a piston 58 to which the driving force from the conversion mechanism 56 is transmitted, and a gripping mechanism 62 that is provided at the lower part of the body 60 and grips the workpiece W under its opening and closing action. .

  The drive unit 52 is composed of a rotational drive source such as a stepping motor or a DC motor, and the drive force of the drive unit 52 is via a pinion gear (first gear) 66 of a gear mechanism 54 mounted on the drive shaft 64. Are transmitted to a plurality of satellite gears (second gears) 68.

  As shown in FIGS. 1 and 2, the gear mechanism 54 is provided in a casing (body) 70 connected to a lower portion of the driving unit 52 and the casing 70, and is driven under the driving action of the driving unit 52. A rotating pinion gear 66 and a plurality of (for example, three) satellite gears 68 that are arranged radially outwardly from the pinion gear 66 and respectively mesh with the pinion gear 66 (see FIG. 3).

  The pinion gear 66 is attached to the drive shaft 64 of the drive unit 52 protruding toward the inside of the casing 70 and rotates integrally under the drive action of the drive unit 52.

  The satellite gears 68 are formed in substantially the same shape, are rotatably supported by gear pins 76 of a gear holder (rotating member) 74 in the conversion mechanism 56, and are formed on the inner peripheral surface of the casing 70. It meshes with the part 78. A disk-shaped holding plate 80 is mounted on the upper portion of the gear pin 76 so that the satellite gear 68 is axially supported by the gear holder 74 and the holding plate 80 in a state where the satellite gear 68 is pivotally supported with respect to the gear pin 76. Displacement in the directions of arrows A1 and A2) is restricted. The holding plate 80 is fixed to the gear holder 74 via a fixing screw 82 screwed to the gear pin 76.

  That is, the pinion gear 66 is disposed at the center of the plurality of satellite gears 68, and the outer peripheral sides of the satellite gears 68 are meshed with the inner teeth 78. Then, the pinion gear 66 rotates under the rotational action of the drive unit 52, so that the plurality of satellite gears 68 meshed with the pinion gear 66 are engaged with the internal teeth 78 of the casing 70. Revolve around 66. Thereby, the gear holder 74 on which the satellite gear 68 is supported is rotationally displaced inside the cam body (body) 84 in the casing 70 and the conversion mechanism 56.

  As shown in FIGS. 1 and 2, the conversion mechanism 56 includes a cam body 84 that is sandwiched between the casing 70 and the body 60, and a gear holder 74 that is rotatably provided inside the cam body 84. Note that the cam body 84 and the casing 70 are fastened together between the drive unit 52 and the body 60.

  The cam body 84 is formed of a resin material, and its substantially central portion protrudes toward the body 60 (in the direction of the arrow A1), and its tip end is inserted into the through hole 86 of the body 60, and is an end surface on the drive portion 52 side. A recess 88 is formed that is recessed in a substantially circular cross section from the side toward the body 60 (in the direction of arrow A1). As shown in FIG. 2, the cam body 84 is connected to the casing 70 and the body 60, so that the outer shape thereof is formed in a rectangular shape. It is formed to be recessed in shape. Further, the cam body 84 has an insertion hole 90 penetrating substantially in the center, and is formed in a circumferential shape on the radially outer side of the insertion hole 90, and a lifting rail (the height H with respect to the bottom wall surface 88 a of the recess 88 gradually changes). A guide portion) 92 and a stopper portion 94 for restricting the rotational displacement of the gear holder 74 in the recess 88.

  As shown in FIGS. 2 and 4, the elevating rail 92 is formed with a substantially constant width in the radial direction, and its height dimension H is clockwise (arrow R1) when the cam body 84 is viewed from the drive unit 52 side. In the direction) from the bottom wall surface 88a.

  Specifically, for example, as shown in FIGS. 4 and 5, when the base line D of the elevating rail 92 extending radially outward from the insertion hole 90 is set as the initial position, the base line D is 45 °. The height dimension H from the bottom wall surface 88a in the range E1 is set to 0 because it is flush with the bottom wall surface 88a, and the height dimension H gradually increases in the range E2 from the 45 ° position to 225 °. It is set to increase. And the raising / lowering rail 92 is set to the planar shape which becomes a substantially constant height dimension H within the range E3 from a position of 225 ° to 300 ° with respect to the base line D, and is 300 ° to 360 °, that is, Within the range E4 up to the position of the base line D, the height dimension H is set to 0, which is again flush with the bottom wall surface 88a. Thus, the height dimension H of the elevating rail 92 is set to a different value depending on the position along the circumferential direction of the cam body 84. The relationship between the height dimension H of the elevating rail 92 and the angle with respect to the base line D is not limited to the above-described numerical values, and is arbitrarily set according to the use environment of the workpiece gripping chuck 50.

  The stopper portion 94 is formed in a substantially arc shape in cross section along the inner peripheral surface of the recess 88, slightly protrudes radially inward from the inner peripheral surface, and a predetermined length from the upper surface of the cam body 84 (on the drive portion 52 side ( It protrudes in the direction of arrow A2 (see FIG. 2).

  As shown in FIGS. 2, 3 and 6, the gear holder 74 is made of a resin material and has a plate portion 96 having a substantially circular cross section, and a plurality of gear pins protruding upward from the plate portion 96. 76, a holding part 98 projecting downward from a substantially central part of the plate part 96, a hole part 100 penetrating the holding part 98 and the plate part 96, and a roller hole 102 formed in the plate part 96. A roller 104 that is rotatably held via the outer periphery of the plate portion 96, and a locking portion (stopper) 106 that protrudes radially outward from the outer peripheral surface of the plate portion 96.

  The gear pins 76 are arranged on the same diameter and spaced apart from each other with the hole 100 as a center, and the protruding amounts of the gear pins 76 are set to be substantially the same. The satellite gears 68 are inserted into the gear pins 76, respectively. That is, the number of gear pins 76 is set corresponding to the number of satellite gears 68.

  As shown in FIG. 1, the holding portion 98 is inserted into the insertion hole 90 of the cam body 84, and the first shaft portion 108 of the piston 58 is inserted into the inside thereof through the hole portion 100. Is engaged with the step 108a. Then, by mounting the locking ring 110 on the first shaft portion 108 of the piston 58 via the annular groove, the displacement of the gear holder 74 in the axial direction (arrow A1, A2 direction) with respect to the piston 58 is regulated, The gear holder 74 and the piston 58 are integrally displaced.

  As shown in FIG. 6, the roller hole 102 is formed so as to open in a substantially rectangular shape in cross section, and is disposed at a position outside the radius of the hole 100 and between adjacent gear pins 76. Specifically, the roller hole 102 is disposed on an imaginary line S connecting one gear pin 76 and the other gear pin 76, and one side of the roller hole 102 extending toward the gear pin 76 side is the imaginary line S. It is set longer than one side substantially orthogonal.

  A disk-shaped roller 104 rotatably supported by a roller shaft (support shaft) 112 is inserted into the roller hole 102, and the roller shaft 112 is a plate portion formed so as to sandwich the roller hole 102. It is held by being inserted into 96 first pin holes 114 and second pin holes 116 formed on the holding portion 98 side. Since the first pin hole 114 is formed so as to penetrate the outer peripheral surface of the plate portion 96, the roller shaft 112 is transferred from the first pin hole 114 to the roller 104 with the roller 104 disposed in the roller hole 102. And the tip of the roller shaft 112 is inserted into the second pin hole 116, so that the roller 104 is rotatably supported inside the roller hole 102.

  As shown in FIG. 1, the roller 104 slightly protrudes from the upper surface of the plate portion 96 through the roller hole 102 and protrudes by a predetermined length from the lower surface of the plate portion 96, and its outer peripheral surface is the cam body 84. It contacts the lifting rail 92. That is, the roller 104 is provided at a position facing the lifting rail 92 when the gear holder 74 is attached to the cam body 84.

  In other words, the axis of the gear holder 74 and the axis of the roller 104 are arranged so as to be substantially orthogonal, and the rotational direction of the gear holder 74 and the rotational direction of the roller 104 are substantially orthogonal.

  As shown in FIGS. 2, 3, and 6, the locking portion 106 protrudes from the outer peripheral surface of the plate portion 96 by a predetermined length radially outward, and when the gear holder 74 is rotationally displaced in the cam body 84, the stopper portion Rotation displacement is regulated by contacting with 94.

  As shown in FIG. 1, a through hole 86 penetrating along the axial direction (arrows A <b> 1 and A <b> 2) is formed inside the body 60, and a long piston 58 is displaced inside the through hole 86. It is provided freely.

  A cylindrical first bearing 118 is inserted into the upper end portion of the through hole 86, and the first shaft portion 108 of the piston 58 is held by the first bearing 118 so as to be displaceable along the axial direction. The first bearing 118 is engaged with a stepped portion 86a formed on the inner wall surface of the through hole 86, and upward displacement (in the direction of the arrow A2) is restricted by a locking ring 72 attached to the annular groove. ing.

  On the other hand, a cylindrical second bearing 120 is inserted into the lower end portion of the through-hole 86, and the second shaft portion 122 of the piston 58 is held by the second bearing 120 so as to be displaceable along the axial direction. The second bearing 120 is engaged with a stepped portion 86 b formed on the inner wall surface of the through hole 86 and is locked by a locking screw 124 screwed into the lower end portion of the through hole 86. Thus, the first and second bearings 118 and 120 are fixed inside the through hole 86.

  The piston 58 includes a first shaft portion 108 formed on one end side and held by the first bearing 118, a second shaft portion 122 formed on the other end side and held by the second bearing 120, And a main body 126 formed between the first shaft portion 108 and the second shaft portion 122 and having a diameter larger than that of the first and second shaft portions 108 and 122 and contacting the inner wall surface of the through hole 86. A spring 128 is interposed between the main body 126 and the first bearing 118, and always urges the piston 58 in a direction in which the piston 58 is separated from the first bearing 118 (arrow A1 direction). A damper 130 made of an elastic material (for example, rubber) is disposed between the bearing 120. The damper 130 is fixed to the end surface of the main body 126.

  The cam body 84 of the conversion mechanism 56 is coupled to the upper end portion of the body 60 via a coupling screw 132.

  The gripping mechanism 62 includes a pair of chucks 136 a and 136 b that are provided in a notch 134 formed in the lower portion of the body 60 and engaged with the second shaft portion 122 of the piston 58. The chucks 136a and 136b are formed to have a substantially L-shaped cross section, and a bent substantially central portion thereof is pivotally supported by a notch portion 134 of the body 60 via a link pin 140. Further, on the one end side of each of the chucks 136a and 136b, a groove 138 that is cut out in a semicircular shape is formed, and is engaged with a piston pin 142 mounted on the second shaft portion 122 of the piston 58, respectively. . On the other hand, the other end portions of the chucks 136 a and 136 b extend downward from a portion pivotally supported by the link pin 140.

  That is, the pair of chucks 136a and 136b engaged with the piston pin 142 under the displacement action along the axial direction of the piston 58 rotates by a predetermined angle with the link pin 140 as a fulcrum, and the pair of chucks 136a, Under the rotating action of 136b, the other end portions open and close so as to approach and separate from each other (in the directions of arrows B and C in FIG. 1). The gripping mechanism 62 grips the workpiece W when the chucks 136a and 136b are rotated in a direction away from each other (arrow B direction) (see FIG. 1) and rotates in a direction approaching each other (arrow C direction). When moved, the gripping state of the workpiece W is released (see FIG. 7).

  The workpiece gripping chuck 50 according to the first embodiment of the present invention is basically configured as described above. Next, its operation, action, and effect will be described. As shown in FIG. 1, the piston 58 is displaced downward (arrow A1 direction) by the elastic force of the spring 128, and the other ends of the pair of chucks 136a and 136b are separated from each other (arrow B). The initial state is a state in which the hole w1 of the workpiece W is gripped by rotating in the direction).

  In the initial state where the workpiece W is gripped by the chucks 136a and 136b, the supply of current from a power source (not shown) to the drive unit 52 is stopped, and no driving force is applied to the gear mechanism 54 and the conversion mechanism 56. In addition, the roller 104 is positioned on the base line D in the cam body 84 and is not in contact with the lifting rail 92. In this case, since the piston 58 is pressed downward by the elastic force of the spring 128, the pair of chucks 136a and 136b is opened under the displacement action of the piston 58, and the hole w1 of the workpiece W is opened. Is gripping.

  Next, a case where the gripping state of the workpiece W is released from this initial state (see FIG. 1) will be described.

  First, a current is supplied from a power source (not shown) to the driving unit 52, and the driving unit 52 is rotated clockwise (in the direction of the arrow R1) by a predetermined amount, whereby the pinion gear 66 is rotated together with the driving shaft 64. Then, the driving force from the driving unit 52 is transmitted to the plurality of satellite gears 68 meshed with the pinion gear 66, and the satellite gear 68 revolves around the pinion gear 66. As a result, the driving force from the drive unit 52 is increased via the gear mechanism 54, and the gear holder 74 supporting the satellite gear 68 is rotated clockwise (arrow R1) when viewed from the drive unit 52 side in the casing 70 and the cam body 84. Direction). The gear holder 74 is always pulled downward by the elastic force of the spring 128 against the piston 58 connected to the gear holder 74.

  At this time, in the gear holder 74, the roller 104 mounted on the gear holder 74 is rotationally displaced clockwise (in the direction of the arrow R1) along the lifting rail 92 of the cam body 84 from the base line D. Since the elevating rail 92 is formed such that its height dimension H gradually increases in the clockwise direction (arrow R1 direction), the roller 104 rotates from the range E2 to the range E3 of the elevating rail 92. As a result, the gear holder 74 on which the roller 104 is supported gradually rises toward the drive unit 52 (in the direction of arrow A2).

  As a result, the piston 58 connected to the gear holder 74 is gradually displaced toward the drive unit 52 (in the direction of arrow A <b> 2) against the elastic force of the spring 128. Note that since the gear holder 74 and the piston 58 are restricted to displacement only in the relative axial direction, the displacement of the gear holder 74 in the rotation direction is not transmitted to the piston 58. In other words, the piston 58 can be displaced only in the axial direction within the through hole 86 of the body 60, and is not rotationally displaced within the through hole 86.

  Then, as shown in FIG. 7, when the piston 58 is displaced toward the drive unit 52 side, the chucks 136a and 136b engaged with the piston 58 via the piston pin 142 have the link pin 140 as a fulcrum. It rotates in the direction (arrow C direction) where the end portions approach each other. As a result, the chucks 136a and 136b are separated from the hole w1 of the workpiece W, and the gripping state on the workpiece W is released. At this time, the roller 104 is in the range E3 in which the height dimension H is set to be the largest in the lifting rail 92, and the range E3 is set in a planar shape having a substantially constant height dimension H. The piston 58 is not displaced along the axial direction, and the chucks 136a and 136b are held in a closed state by a desired amount. That is, the piston 58 becomes a displacement end position where displacement in the axial direction (upward) is restricted.

  Further, the gear holder 74 is further rotationally displaced, and the engaging portion 106 abuts against the stopper portion 94 of the cam body 84, whereby the rotational displacement of the gear holder 74 is restricted and stopped. As a result, the gear holder 74 is positioned in the circumferential direction with respect to the cam body 84, and accordingly, the displacement amount along the axial direction of the piston 58 is controlled, so that the chucks 136a and 136b that open and close via the piston 58 are opened and closed. The amount is controlled to the desired amount.

  On the other hand, when the hole w1 of the workpiece W is gripped again via the gripping mechanism 62, the pair of chucks 136a and 136b that are in the closed state rotated in the directions approaching each other are placed in the hole w1 of the workpiece W in advance. Insert it. Then, by reversing the polarity of the current supplied to the drive unit 52 and rotating the drive unit 52 in the opposite direction (arrow R2 direction), the gear holder 74 is counterclockwise as viewed from the drive unit 52 side. Since the roller 104 of the gear holder 74 is rotationally displaced around (in the direction of arrow R2), the roller 104 of the gear holder 74 is lowered along the lifting rail 92 so as to gradually approach the body 60 side (in the direction of arrow A1). As a result, the gear holder 74 is lowered along the axial direction inside the casing 70 and the cam body 84, and accordingly, the piston 58 is displaced downward along the through hole 86 of the body 60 by the elastic force of the spring 128. To do. At this time, the shock when the piston 58 comes into contact with the second bearing 120 is buffered by the damper 130 attached to the end face of the piston 58.

  As a result, the piston 58 is displaced in the direction away from the drive unit 52 (the direction of the arrow A1), so that the chucks 136a and 136b engaged with the piston 58 via the piston pin 142 have the link pin 140 as a fulcrum. Since the end portions rotate in directions away from each other (arrow B direction), a pair of chucks 136a and 136b inserted into the hole w1 of the workpiece W come into contact with the inner peripheral surface of the hole w1, and the chuck The workpiece W is gripped by 136a and 136b. At this time, the roller 104 is positioned on the base line D of the cam body 84 again after being displaced along the lifting rail 92. That is, the piston 58 is displaced downward by the elastic force of the spring 128, and the displacement end position where the roller 104 provided in the gear holder 74 abuts against the bottom wall surface 88a of the cam body 84 and the downward displacement thereof is restricted. It becomes.

  Further, the displacement amount along the axial direction of the piston 58 described above is equivalent to the height dimension H from the bottom wall surface 88a of the cam body 84 to the range E3 in the lifting rail 92. In other words, the height dimension H of the lifting rail 92 is set in advance based on the displacement amount of the piston 58.

  Then, the gear holder 74 is further rotationally displaced, and the engaging portion 106 abuts against the stopper portion 94 of the cam body 84, whereby the rotational displacement of the gear holder 74 is restricted and stopped. Thereby, the positioning along the circumferential direction of the gear holder 74 with respect to the cam body 84 is performed, and accordingly, the amount of displacement along the axial direction of the piston 58 is controlled, so the chucks 136a and 136b that open and close via the piston 58 are controlled. Is controlled to a desired amount.

  As described above, in the first embodiment, the driving force from the driving unit 52 is transmitted through the pinion gear 66 and the satellite gear 68 of the gear mechanism 54, so that the rotation speed is reduced by a predetermined amount. In addition, the driving force is increased, and a gear holder 74 that supports the plurality of satellite gears 68 is connected to the piston 58, and the gear holder 74 is axially moved (in the directions of arrows A1 and A2) under the rotating action of the satellite gear 68. Can be moved up and down. That is, the gear holder 74 has a function of decelerating and increasing the driving force and a function of converting the driving force into a linear motion via the gear holder 74. Therefore, in the workpiece gripping chuck 50, the gear mechanism 54 and the conversion mechanism 56 provided between the drive unit 52 and the body 60 can be reduced in size and can be configured at low cost.

  In the gear mechanism 54, when the plurality of satellite gears 68 meshed with the pinion gear 66 are displaced along the axial direction via the gear holder 74, they are displaced while revolving due to the rotation of the pinion gear 66. Therefore, it is possible to suitably suppress wear when the pinion gear 66 and the satellite gear 68 are engaged. As a result, the life of the pinion gear 66 and the satellite gear 68 in the gear mechanism 54 can be increased, and the durability of the workpiece gripping chuck 50 can be improved.

  Furthermore, since the gripping force when gripping the workpiece W is held by the elastic force of the spring 128 interposed between the piston 58 and the first bearing 118, the current to the drive unit 52 is somehow caused. Even when the supply is stopped, the workpiece W can be gripped in a reliable and stable state. In other words, the chucks 136a and 136b have a self-holding function that can grip the workpiece W even when the driving force by the driving unit 52 is not biased.

  Furthermore, by providing the cam body 84 with a stopper portion 94 protruding radially inward, and by providing a locking portion 106 protruding radially outward on the outer peripheral surface of the gear holder 74 disposed in the recess 88 of the cam body 84, When the gear holder 74 is rotationally displaced, the engaging portion 106 abuts against the stopper portion 94, so that the rotational displacement can be reliably stopped. Accordingly, the gear holder 74 that is rotationally displaced can be forcibly locked via the stopper portion 94 and the locking portion 106, so that a detection mechanism for detecting the amount of rotation of the gear holder 74 or the drive portion 52 is detected. It is unnecessary to control the rotation amount of the gear holder 74 or the drive unit 52 based on the detection result of the detection mechanism. As a result, compared with the prior art provided with the optical sensor 12 (detection mechanism) for detecting the rotation amount of the motor 3, the cost can be reduced and the workpiece gripping chuck 50 can be configured at a low cost.

  Next, a workpiece gripping chuck 150 according to a second embodiment is shown in FIGS. The same constituent elements as those of the workpiece gripping chuck 50 according to the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the workpiece gripping chuck 150 according to the second embodiment, as shown in FIG. 8 and FIG. 9, a spring 152 is interposed between the piston 58 and the second bearing 120. The cam body 154 is sandwiched between the casing 70 and the drive unit 52, and the elevating rail 156 of the cam body 154 is connected to the gear mechanism 54 side (arrow A1). 1) in that the roller 104 is rotatably provided on the holding plate 158 attached to the gear holder 74 so as to face the lifting rail 156. This is different from the workpiece gripping chuck 50 according to the embodiment.

  As shown in FIG. 8, the piston 58 is displaced upward by the elastic force of the spring 152, and the other ends of the pair of chucks 136 a and 136 b are rotated in a direction approaching each other (arrow C direction). In the initial state in which the workpiece W is gripped, the supply of current to the drive unit 52 is stopped, and the roller 104 is in contact with the bottom wall surface 154a of the cam body 154. In this case, since the piston 58 is pressed upward (in the direction of the arrow A2) by the spring 152, the pair of chucks 136a and 136b are closed and grip the side surface of the workpiece W under the displacement action of the piston 58. is doing.

  Next, when releasing the gripping state of the workpiece W from this initial state (see FIG. 8), a current is supplied to the drive unit 52, so that the pinion gear 66 rotates and a plurality of satellite gears 68. Revolves, and the driving force from the driving unit 52 is increased and transmitted to the gear holder 74. Then, the gear holder 74 and the holding plate 158 are rotationally displaced in the clockwise direction (in the direction of the arrow R1) when viewed from the drive unit 52 side in the casing 70 and the cam body 154, so that the roller 104 extends from the bottom wall surface 154a along the lifting rail 156. As the roller 104 rotates, the gear holder 74 provided with the roller 104 is gradually displaced toward the body 60 side.

  As a result, the piston 58 connected to the gear holder 74 is gradually displaced in the direction away from the drive unit 52 against the elastic force of the spring 152 (in the direction of arrow A1), and the piston 58 is connected via the piston pin 142. The chucks 136a and 136b engaged with each other rotate around the link pin 140 in the direction in which the other ends are separated from each other (arrow B direction) (see FIG. 9). As a result, the chucks 136a and 136b are separated from the side surface of the workpiece W, and the gripping state with respect to the workpiece W is released.

  Further, the gear holder 74 is further rotationally displaced, and the engaging portion 106 abuts against the stopper portion 94 of the cam body 154, whereby the rotational displacement of the gear holder 74 is restricted and stopped. As a result, the gear holder 74 is positioned in the circumferential direction with respect to the cam body 154, and the amount of displacement along the axial direction of the piston 58 is controlled accordingly, so that the chucks 136a and 136b that open and close via the piston 58 are opened and closed. The amount is controlled to the desired amount.

  The electric actuator according to the present invention is not limited to the workpiece gripping chucks according to the first and second embodiments described above, and various configurations can be adopted without departing from the gist of the present invention. is there.

1 is an overall longitudinal sectional view showing a state in which a workpiece gripping chuck according to a first embodiment of the present invention grips a workpiece. FIG. 2 is an exploded perspective view of a gear mechanism and a conversion mechanism in the workpiece gripping chuck of FIG. 1. It is a top view which shows the gear mechanism and conversion mechanism of FIG. FIG. 2 is a single plan view of the cam body of FIG. 1. FIG. 5 is a characteristic curve diagram showing a relationship between a range E1 to E4 in the circumferential direction with a base line D as a fulcrum and a height dimension H in the lifting rail of FIG. It is a single-piece | unit top view of the gear holder of FIG. FIG. 2 is an overall longitudinal sectional view showing a non-gripping state in which the workpiece gripping chuck of FIG. 1 is not gripping a workpiece. It is a whole longitudinal cross-sectional view which shows the state which the workpiece | work holding chuck | zipper concerning the 2nd Embodiment of this invention hold | gripped the workpiece | work. FIG. 9 is an overall longitudinal sectional view showing a non-gripping state in which the workpiece gripping chuck of FIG. 8 is not gripping a workpiece. It is a front view of the chuck mechanism which concerns on a prior art.

Explanation of symbols

50, 150 ... chuck for gripping workpiece 52 ... drive unit 54 ... gear mechanism 56 ... conversion mechanism 58 ... piston 60 ... body 62 ... gripping mechanism 64 ... drive shaft 66 ... pinion gear 68 ... satellite gear 70 ... casing 74 ... gear holder 76 ... Gear pin 78 ... Internal tooth part 80, 158 ... Holding plate 84, 154 ... Cam body 88 ... Recess 88a, 154a ... Bottom wall surface 92, 156 ... Elevating rail 94 ... Stopper part 96 ... Plate part 102 ... Roller hole 104 ... Roller 106 ... Engagement Stop part 112 ... Roller shaft 128, 152 ... Spring 130 ... Damper 136a, 136b ... Chuck 140 ... Link pin 142 ... Piston pin

Claims (4)

Body,
A drive unit coupled to the body and rotationally driven under energization;
A gear mechanism having a first gear coupled to the driving unit and rotationally driven, and a second gear revolving around the first gear;
A rotating member that rotatably supports the second gear and that is rotationally displaced about the axis of the body under the rotating action of the second gear;
A displacement mechanism for displacing the rotating member along the axial direction of the body under the rotating action of the rotating member;
A piston coupled to the rotating member and provided to be displaceable along an axial direction of the body;
A spring having a resilient force to press the piston toward one side in the axial direction;
An electric actuator comprising: The electric actuator according to claim 1, wherein
The displacement mechanism is provided on the rotating member, and is rotatably supported via a support shaft substantially orthogonal to the axis of the rotating member;
A guide portion that is formed at a position facing the roller when the rotating member rotates, and whose height dimension changes along the axial direction of the rotating member;
With
The roller rotates along the guide portion under the rotating action of the rotating member, and the elastic force of the spring is biased in a direction of pressing the roller toward the guide portion via the piston. An electric actuator characterized by that. The electric actuator according to claim 1 or 2,
The electric actuator according to claim 1, wherein the rotating member is provided with a stopper for restricting the rotational displacement of the rotating member by being engaged with the body. The electric actuator according to any one of claims 1 to 3,
The electric actuator is a gripping device including a pair of chucks capable of gripping a workpiece by opening and closing under the displacement action of the piston.

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