JP2017040323A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator that can reduce load on a motor while suppressing wear of a vibration prevention mechanism.SOLUTION: The actuator 10 includes: a rod 11 fixed to a slide part 31, linearly moving together with a ball screw nut 72 and the slide part 31 and formed with an insertion hole 11a for inserting a tip of a ball screw shaft 71; the vibration prevention mechanism 110 mounted to the tip of the ball screw shaft 71 and suppressing swinging rotation of the ball screw shaft 71; and a protection pipe 120 covering an inner peripheral surface of the insertion hole 11a of the rod 11 and coming into contact with the vibration prevention mechanism 110.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an actuator.

  In a rod type actuator, for example, the rotational movement of a motor is transmitted to a slide part via a ball screw, so that the rod fixed to the slide part moves forward and backward. Thereby, an arbitrary tool attached to the tip of the rod performs various operations such as pressing the workpiece to be worked. In such an actuator, swinging tends to occur at the tip of the ball screw shaft (the free end opposite to the drive end to which the motor is connected). In particular, the higher the rotational movement of the motor, the greater the deflection of the ball screw shaft due to bending and its own weight, and the greater the deflection of the tip of the ball screw shaft. For this reason, the critical speed of the ball screw shaft cannot be increased, and the motor cannot be rotated at a high speed.

  On the other hand, Patent Documents 1 and 2 disclose an actuator provided with a steady stop mechanism that suppresses the swing of the tip of the ball screw shaft. Since the tip of the ball screw shaft is supported by the inner periphery of the hole of the rod through this steadying mechanism, the swing of the tip of the ball screw shaft can be suppressed.

JP 2013-36606 A JP 2014-202286 A

  In the actuators described in Patent Documents 1 and 2, as the rod moves forward and backward, the steady rest mechanism slides on the inner peripheral surface of the hole of the rod. Due to this sliding, the components of the steady rest mechanism that come into contact with the inner peripheral surface of the rod hole of the steady rest mechanism are worn. In particular, the larger the actuator, the larger the contact area between the steady rest mechanism and the inner peripheral surface of the hole, and the greater the sliding resistance between the steady rest mechanism and the inner peripheral surface of the rod hole. Becomes larger. As a result, there is a possibility that the smooth movement of the rod is hindered, and accordingly, a load on the motor may be increased.

  The present invention has been made under the circumstances described above, and it is an object of the present invention to provide an actuator that can suppress the wear of the steady rest mechanism and reduce the load on the motor.

To achieve the above objective, the actuator
A motor with a rotating shaft;
A ball screw having a ball screw shaft that rotates together with the rotational motion of the rotational shaft, and a ball screw nut that moves linearly with the rotational motion of the ball screw shaft;
A slide portion fixed to the ball screw nut and moving linearly with the ball screw nut;
A rod fixed to the slide portion, linearly moving with the ball screw nut and the slide portion, and having an insertion hole for inserting a tip of the ball screw shaft;
An anti-sway mechanism that is attached to the tip of the ball screw shaft and suppresses the whirling of the ball screw shaft;
A protective portion that covers the inner peripheral surface of the insertion hole of the rod and contacts the steadying mechanism;
It is characterized by having.

  At least the inner peripheral surface of the protection portion has a first friction coefficient between the protection portion and the steady stop mechanism, and the steady stop mechanism when the steady stop mechanism contacts the inner peripheral surface of the insertion hole. And a material smaller than a second friction coefficient between the insertion hole and the insertion hole.

  At least the inner peripheral surface of the protection part may be a smooth surface having a lower roughness than the inner peripheral surface of the insertion hole.

  The protective part may be a substantially cylindrical member whose outer diameter is substantially equal to the inner diameter of the rod.

  The protective portion, which is the substantially cylindrical member, may have an O-shaped cross section perpendicular to the axial direction of the rod.

  The protective portion, which is a substantially cylindrical member, has a C-shaped cross section perpendicular to the axial direction of the rod by forming slits connecting both ends of the rod in the axial direction. Also good.

  The protective part may have an elastic force that expands in diameter in a direction in which the slit widens.

  The said protection part may be comprised from the some division body divided | segmented along the axial direction of the said rod.

  The protective part may be a coating layer formed by coating the inner peripheral surface of the insertion hole of the rod.

  The material of the protection part may be formed of a fluororesin.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to suppress abrasion of a steadying prevention mechanism, the load to a motor can be reduced.

It is a disassembled perspective view when the cover of the actuator which concerns on 1st Embodiment of this invention is removed. It is sectional drawing of an actuator when a cover is removed. It is an exploded sectional view of an actuator. It is a perspective view of a guide device. It is sectional drawing of a guide apparatus. It is a disassembled perspective view of a guide apparatus. It is a partial cross section figure near the front-end | tip part of the ball screw axis | shaft to which the steadying mechanism was attached. It is a disassembled perspective view of a steadying mechanism. It is an exploded perspective view for explaining attachment of a ball screw and a protection pipe to a guide device. It is sectional drawing (the 1) for demonstrating operation | movement of an actuator. It is sectional drawing (the 2) for demonstrating operation | movement of an actuator. FIG. 6 is a sectional view (No. 3) for explaining the operation of the actuator. It is sectional drawing (the 1) for demonstrating the effect | action of a steady rest mechanism. It is sectional drawing for demonstrating the effect | action of a steadying mechanism (the 2). (A) is a perspective view which shows the protection pipe which concerns on 1st Embodiment of this invention. (B) is a perspective view which shows the protection pipe which concerns on 2nd Embodiment of this invention. (A) is sectional drawing of a protection pipe. (B) is sectional drawing when a protection pipe is attached to the insertion hole of a rod. It is a perspective view of a protection pipe concerning modification 1 of the present invention. It is a perspective view of a protection pipe concerning modification 2 of the present invention. It is a perspective view of a protection pipe concerning modification 3 of the present invention.

<< First Embodiment >>
Hereinafter, an actuator 10 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 11B. In order to facilitate understanding, XYZ coordinates are set and referred to as appropriate.

  As shown in FIG. 1, the actuator 10 is a rod-type actuator having a rod 11 that reciprocates in the Y-axis direction. The actuator 10 includes a rod 11, a motor unit 20, a front housing 80, a rear housing 90, and a cover 18.

  The cover 18 is formed, for example, by extruding aluminum. As shown in FIG. 1, the cover 18 is fixed to the front housing 80 and the rear housing 90 by bolts 19.

  As shown in FIG. 2, the actuator 10 includes a guide device 30 having a slide portion 31 that guides the rod 11 in the Y-axis direction in addition to the rod 11 and the like, and a ball that converts the rotational motion of the motor unit 20 into linear motion. The screw 70, the steadying mechanism 110, and the protective pipe 120 fitted into the insertion hole 11a of the rod 11 are provided.

  As shown in FIG. 3, the rod 11 is a member having an insertion hole 11a formed therein. The rod 11 has a cylindrical rod body 12 and a tip fitting 13. The rod body 12 is made of, for example, metal, and preferably made of aluminum. However, the material of the rod body 12 is arbitrary and may be a metal other than aluminum. For example, stainless steel may be used. The rod body 12 is formed in a substantially cylindrical shape by drawing. By being formed by drawing, the cross section of the insertion hole 11a is formed in a circular shape with high roundness. A tip end fitting 13 having an external thread formed on the outer periphery is fixed to the end portion on the −Y side of the rod 11 by being screwed. Further, a male thread portion is formed on the outer periphery of the end portion on the + Y side of the rod 11.

  The motor unit 20 includes a motor 21, a motor housing 22 that houses the motor 21, and an actuator cable 24.

  The motor 21 includes an output shaft 23, a rotor, a stator, an encoder, a speed reducer, and the like. Electric power from the power source is supplied to the motor 21 via the actuator cable 24. When electric power is supplied to the motor 21, the rotor of the motor 21 rotates. The rotational motion of the rotor is decelerated at a predetermined reduction ratio by a reducer, for example, and is output to the output shaft 23. A coupling is connected to the tip of the output shaft 23. The motor housing 22 is attached to the rear housing 90 by bolts 25.

  The guide device 30 guides the rod 11 in both the + Y direction and the −Y direction by fixing the rod 11 to the slide portion 31. As shown in FIGS. 4 and 5, the guide device 30 includes a slide portion 31, a base 60, and a ball 50 that is disposed between the slide portion 31 and the base 60 and functions as a rolling element. The ball 50 is made of a highly rigid material, specifically, a steel material. A plurality of balls 50 are arranged between the slide portion 31 and the base 60.

  As shown in FIG. 6, the slide portion 31 includes a slide portion main body 32 and a rolling element storage unit 40.

  The slide part main body 32 is a substantially rectangular parallelepiped member made of metal, for example. The slide part main body 32 is formed with a through hole 32a penetrating in the Y-axis direction. As shown in FIG. 3, an internal thread portion 32 b is formed on the inner peripheral surface in the vicinity of the opening on the −Y side of the through hole 32 a of the slide portion main body 32. The rod 11 is fixed to the slide portion main body 32 by the male screw portion on the + Y side of the rod 11 being screwed into the female screw portion 32 b of the through hole of the slide portion main body 32.

  As shown in FIG. 5, the rolling element storage unit 40 is fixed to the lower surface (the surface on the −Z side) of the slide portion main body 32. A rolling element circulation path 41 is formed inside the rolling element storage unit 40. A plurality of balls 50 are arranged in the rolling element circulation path 41.

  As shown in FIG. 6, the base 60 is a member whose longitudinal direction is the Y-axis direction. The base 60 includes a bottom plate portion 61 and side wall portions 62R and 62L formed on both sides of the bottom plate portion 61. The base 60 is formed, for example, by extruding aluminum. Concave portions are formed in the −X side surface of the side wall portion 62R and the + X side surface of the side wall portion 62L, respectively. Guide rails 63R and 63L having a longitudinal direction in the Y-axis direction are attached to the recess. Grooves are formed in the −X side surface of the guide rail 63R and the + X side surface of the guide rail 63L, respectively. The groove portions are formed to face each other, and the inner surface of the groove portion is configured as a substantially curved surface.

  The guide device 30 is completed by attaching the slide portion 31 to the base 60. Then, as shown in FIG. 3, the + Y side end portion of the rod 11 is inserted into the through hole 32 a of the slide portion main body 32 of the slide portion 31. The rod 11 is fixed to the slide portion 31 of the guide device 30 by screwing the male screw portion formed at the end on the + Y side of the rod 11 into the female screw portion 32b formed in the through hole 32a. The

  The ball screw 70 has a ball screw shaft 71 and a ball screw nut 72.

  The ball screw shaft 71 includes a ball screw shaft main body 71a whose outer peripheral surface is configured as a spiral male screw surface, and a connecting member 73 attached to the + Y side end of the ball screw shaft main body 71a. The connecting member 73 is connected to the output shaft 23 of the motor unit 20, thereby rotating with the rotation of the output shaft 23. Thereby, the rotational motion of the output shaft 23 is transmitted to the ball screw shaft 71.

  The ball screw nut 72 is disposed on the outer periphery of the ball screw shaft main body 71 a of the ball screw shaft 71. A female screw portion is formed on the inner peripheral surface of the ball screw nut 72. The ball screw nut 72 is fitted into the ball screw shaft 71 via a highly rigid sphere. Thereby, the rotational motion of the ball screw shaft 71 is converted into the linear motion of the ball screw nut 72.

  As shown in FIGS. 7 and 8, the steadying mechanism 110 is a member for suppressing the swinging of the tip end portion 71 c of the ball screw shaft 71. The steady rest mechanism 110 is fitted into the tip portion 71 c of the ball screw shaft 71. The steadying mechanism 110 is rotatably locked by a locking member 113. The steady rest mechanism 110 has a steady rest mechanism main body 111 and an elastic member 112.

  The steady rest mechanism main body 111 is formed in a ring shape with a through hole 111a formed in the center. The steady rest mechanism main body 111 is made of polyacetal, for example. The steady-rest mechanism main body 111 is formed with a plurality of air holes 111b formed at equal intervals along the outer periphery of the through hole 111a. The air hole 111b is a through-hole penetrating in the axial direction (Y-axis direction) of the ball screw shaft 71, and is formed along the Y-axis direction. In the present embodiment, six air holes 111b are formed. Further, a groove 111c for fitting the elastic member 112 is formed on the outer periphery of the steady rest mechanism main body 111.

  The elastic member 112 is, for example, an O-ring. The material of the elastic member 112 is, for example, rubber, and preferably fluororubber. However, the material of the elastic member 112 is not limited to this, and may be rubber other than fluoro rubber. The elastic member 112 has an outer diameter that is slightly larger than the inner diameter of the protective pipe 120. As a result, when the tip 71c of the ball screw shaft 71 is inserted into the protective pipe 120 of the rod 11, the elastic member 112 is elastically deformed, and between the outer periphery of the elastic member 112 and the inner periphery of the protective pipe 120. Can close the gap. In the present embodiment, the steadying mechanism 110 has one elastic member 112. However, the present invention is not limited to this, and two or more elastic members 112 may be provided.

  The locking member 113 is fitted into a locking groove 71 b formed on the outer periphery of the tip end portion 71 c of the ball screw shaft 71, thereby preventing the steadying mechanism 110 from coming off.

  The ball screw 70 to which the steady rest mechanism 110 is attached is fixed to the guide device 30 as shown in FIGS. Specifically, the tip 71c of the ball screw shaft 71 is inserted from the + Y side into the through hole 32a of the slide body 32, and the ball screw nut 72 is disposed in the through hole 32a. The ball screw 70 is fixed to the guide device 30 by screwing the bolt 74 into the slide portion main body 32 from the side and fastening it.

  Further, when the ball screw 70 is fixed to the guide device 30, the steadying mechanism 110 is disposed in the protective pipe 120 of the rod 11. At this time, the outer periphery of the elastic member 112 of the steadying mechanism 110 is in contact with the inner peripheral surface of the protective pipe 120, and the elastic member 112 is connected to the inner peripheral surface of the protective pipe 120 and the groove 111 c of the steadying mechanism main body 111. Is compressed in the radial direction. As a result, the tip 71 c of the ball screw shaft 71 is supported on the inner peripheral surface of the protective pipe 120 via the steadying mechanism 110, and thus supported by the rod 11.

  The protective pipe 120 is a cylindrical member whose outer diameter is substantially equal to the inner diameter of the insertion hole 11a and whose XZ plane is O-shaped. The protective pipe 120 is inserted and fitted into the insertion hole 11a. Thereby, the inner peripheral surface of the insertion hole 11a is covered with the protective pipe 120. The friction coefficient μ1 between the protective pipe 120 and the elastic member 112 is smaller than the friction coefficient μ2 between the elastic member 112 and the insertion hole 11a when the elastic member 112 contacts the inner peripheral surface of the insertion hole 11a. It is formed from material. For example, the protective pipe 120 is made of a synthetic resin material such as polyacetal (POM) or polytetrafluoroethylene (PTFE), or a plastic material. Note that the material of the protective pipe 120 is not limited to this, and if the friction coefficient μ1 between the elastic member 112 and the elastic member 112 is smaller than the friction coefficient μ2 between the elastic member 112 and the insertion hole 11a, the above-described material is used. Other than that. For example, the inner peripheral surface of the protective pipe 120 may be processed or processed so as to be a smoother surface than the inner peripheral surface of the insertion hole 11a. Specifically, any one of arithmetic average roughness, maximum height, and ten-point average roughness, which is a parameter for defining the surface roughness on the inner peripheral surface of the protective pipe 120, is the inner peripheral surface of the insertion hole 11a. The processing or processing may be performed so as to be lower than the corresponding parameter in. As described above, the inner peripheral surface of the protective pipe 120 is formed more smoothly than the inner peripheral surface of the insertion hole 11a before the protective pipe 120 is attached.

  As shown in FIG. 3, the length L1 of the protective pipe 120 in the Y-axis direction is equal to, for example, the length L2 (hole depth) of the insertion hole 11a in the Y-axis direction. The protective pipe 120 is arranged in the insertion hole 11a so as not to move in the Y-axis direction by attaching the tip fitting 13 to the rod 11 after being inserted into the insertion hole 11a of the rod 11.

  The front housing 80 is fixed to the −Y side of the guide device 30 with bolts. A through hole for passing the rod 11 is formed in the front housing 80, and an oilless bearing 82 is disposed on the inner peripheral surface of the through hole. The oilless bearing 82 supports the rod 11 so as to be movable in the Y-axis direction.

  The rear housing 90 is fixed to the + Y side of the guide device 30 with bolts. The rear housing 90 has a through hole into which the ball screw shaft 71 is inserted, and a ball bearing 92 is disposed on the inner peripheral surface of the through hole. The ball bearing 92 is fitted from the + Y side of the through hole and is fixed by a bearing retainer. The ball screw shaft 71 is rotatably supported by the ball bearing 92.

  The operation of the actuator 10 configured as described above will be described with reference to FIGS. 10A to 10C, FIGS. 11A, and 11B.

  First, when power is supplied to the motor 21 of the motor unit 20, as shown in FIG. 10A, the output shaft 23 of the motor 21 rotates in a predetermined direction. When the output shaft 23 rotates (forward rotation) in a predetermined direction, the ball screw shaft 71 connected to the output shaft 23 rotates together with the output shaft 23.

  When the ball screw shaft 71 rotates, as shown in FIG. 10B, the ball screw nut 72 linearly moves in the −Y direction, for example, as the ball screw shaft 71 rotates. When the ball screw nut 72 moves in the −Y direction, the slide portion 31 of the guide device 30 fixed to the ball screw nut 72 also moves in the −Y direction together with the ball screw nut 72. At this time, as shown in FIG. 6, when the ball 50 rolls on the guide rails 63R and 63L, the slide portion 31 moves smoothly. Returning to FIG. 10B, when the slide portion 31 moves in the −Y direction, the rod 11 fixed to the slide portion 31 also moves in the −Y direction together with the slide portion 31. Thereby, the tip metal fitting 13 attached to the tip of the rod 11 moves in the -Y direction.

  Further, as shown in FIG. 11A, the rod 11 moves in the −Y direction, whereas the ball screw shaft 71 rotates without moving in the −Y direction. For this reason, the steadying mechanism 110 attached to the ball screw shaft 71 slides with respect to the inner peripheral surface of the protective pipe 120. Specifically, the elastic member 112 of the steadying mechanism 110 slides on the inner peripheral surface of the protective pipe 120. The volume of the space S defined by the protective pipe 120 and the surface on the −Y side of the steady rest mechanism 110 increases as the rod 11 moves in the −Y direction. At this time, the air in the space S flows into the space S from the air hole 111b of the steadying mechanism main body 111, and the internal pressure of the space S is kept constant.

  Thus, the movement of the rod 11 and the tip fitting 13 in the −Y direction is completed.

  Next, when the output shaft 23 of the motor unit 20 rotates (reverses) in a direction opposite to a predetermined direction, the ball screw shaft 71 connected to the output shaft 23 is moved together with the output shaft 23 as shown in FIG. 10C. Rotate.

  When the ball screw shaft 71 rotates, the ball screw nut 72 linearly moves in the + Y direction as the ball screw shaft 71 rotates. When the ball screw nut 72 moves in the + Y direction, the slide portion 31 of the guide device 30 fixed to the ball screw nut 72 also moves in the + Y direction together with the ball screw nut 72. When the slide part 31 moves in the + Y direction, the rod 11 fixed to the slide part 31 also moves in the + Y direction together with the slide part 31. Thereby, the tip metal fitting 13 attached to the tip of the rod 11 moves in the + Y direction.

  Further, as shown in FIG. 11B, the rod 11 moves in the + Y direction, whereas the ball screw shaft 71 rotates without moving in the + Y direction. For this reason, the space S becomes smaller as the rod 11 moves in the + Y direction. Thereby, the air in the space S flows out of the space S through the air hole 111b of the steady-rest mechanism main body 111, and the internal pressure of the space S is kept constant.

  As described above, the movement of the rod 11 and the tip fitting 13 in the + Y direction is completed, and the rod 11 and the tip fitting 13 return to the initial positions.

  As described above, the actuator 10 according to the first embodiment includes the protective pipe 120 that covers the inner peripheral surface of the insertion hole 11 a of the rod 11 and contacts the elastic member 112 of the steadying mechanism 110. In this protective pipe 120, the friction coefficient μ1 between the elastic member 112 and the elastic member 112 is larger than the friction coefficient μ2 between the elastic member 112 and the insertion hole 11a when the elastic member 112 contacts the inner peripheral surface of the insertion hole 11a. It is formed from a small material. For this reason, wear of the elastic member 112 of the steady rest mechanism 110 can be suppressed. Further, the load on the motor 21 can be reduced.

  For example, in the case of a conventional actuator that does not have the protective pipe 120, the elastic member 112 formed of rubber slides on the inner peripheral surface of the insertion hole 11a of the rod 11 formed of metal. Since the friction coefficient μ2 between the elastic member 112 made of rubber and the rod 11 made of metal is relatively large, the amount of wear of the elastic member 112 accompanying the use of the actuator 10 also increases. As a result, the smooth movement of the rod 11 in the Y-axis direction may be hindered, and accordingly, the load on the motor 21 may increase.

  In contrast, in the first embodiment, since the cylindrical protective pipe 120 made of resin is fitted into the insertion hole 11a of the rod 11, the elastic member 112 made of rubber is made of metal. It does not contact the rod 11 and slides on the inner peripheral surface of the protective pipe 120 made of resin. Since the friction coefficient μ1 between the elastic member 112 formed of rubber and the protective pipe 120 formed of resin is smaller than the friction coefficient μ2, wear of the elastic member 112 due to use of the actuator 10 can be suppressed. Further, since the friction coefficient μ1 between the elastic member 112 and the protective pipe 120 is smaller than the friction coefficient μ2, the sliding resistance of the steadying mechanism 110 with respect to the insertion hole 11a of the rod 11 can be reduced. For this reason, the rod 11 can be moved smoothly and the load on the motor 21 can be reduced accordingly. As a result, the operation of the actuator 10 can be stabilized.

  Further, since the wear of the elastic member 112 based on the friction between the inner peripheral surface of the insertion hole 11a of the rod 11 and the elastic member 112 can be suppressed, the tip 71c of the ball screw shaft 71 is connected to the protective pipe 120. Thus, the rod 11 can be stably supported. For this reason, it is difficult for resonance to occur in the ball screw shaft 71, and the swinging of the tip end portion 71c of the ball screw shaft 71 can be effectively suppressed. As a result, it is possible to suppress noise or abnormal noise caused by the swinging of the tip 71c of the ball screw shaft 71.

  Further, since the swinging of the tip 71c of the ball screw shaft 71 can be effectively suppressed, the rotation of the ball screw shaft 71 can be speeded up. As a result, the moving speed of the rod 11 and the slide part 31 can be increased and the stroke can be increased. Further, the critical speed of the ball screw shaft 71 of the actuator 10 can be improved.

  Further, since the protective pipe 120 is a cylindrical member formed from a resin, it is easy to obtain and does not require any special processing, so that the elastic member of the steady rest mechanism 110 is maintained while maintaining the manufacturing cost. The wear of 112 can be suppressed. Moreover, since it is only necessary to fit the protective pipe 120 into the rod 11 of the actuator 10 already installed in the field, it is possible to suppress the wear of the elastic member 112 of the steady rest mechanism 110 while suppressing the manufacturing cost.

<< Second Embodiment >>
Hereinafter, the protection pipe 120A according to the second embodiment of the present invention will be described with reference to FIGS. 12A and 12B. In order to facilitate understanding, XYZ coordinates are set and referred to as appropriate. In addition, the same code | symbol is used about the structure same or equivalent to 1st Embodiment.

  As shown in FIGS. 12A and 12B, the protective pipe 120A has a groove-like slit 121 connecting both ends along the Y-axis direction, and an outer diameter D1 of the protective pipe 120A is an inner diameter D2 of the insertion hole 11a. It is different from the protective pipe 120 according to the first embodiment in that it is slightly larger than the first embodiment.

  The protective pipe 120 </ b> A is made of a fluororesin material as in the protective pipe 120. The protection pipe 120A has a slit 121, so that the XZ plane is formed in a C-shape. When the slit 121 is narrowed in the circumferential direction (direction R1 shown by the arrow in FIG. 12B (B)), the protective pipe 120A has a diameter expanded in the direction in which the slit 121 expands in the circumferential direction (the direction opposite to the direction R1). It has an elastic force. One slit 121 is formed linearly along the Y-axis direction.

  The protection pipe 120 </ b> A is inserted into the insertion hole 11 a of the rod 11 in a reduced diameter state. The protective pipe 120A inserted into the insertion hole 11a is expanded to the original diameter by elastic recovery and is fixed inside the insertion hole 11a. Moreover, since the protection pipe 120A has an elastic force that extends in the circumferential direction, it is firmly fixed inside the insertion hole 11a. Also. The slit 121 of the protective pipe 120A after insertion is configured as a groove-like grease reservoir 122 in which grease for smoothly moving the steady stop mechanism 110 is accumulated.

  As described above, in the second embodiment, since the protective pipe 120A is fitted into the insertion hole 11a of the rod 11, the wear of the elastic member 112 of the steadying mechanism 110 can be suppressed. As a result, the ball screw shaft 71 is less likely to resonate, and the whirling of the tip 71c of the ball screw shaft 71 can be effectively suppressed. As a result, it is possible to suppress noise caused by the swinging of the tip 71c of the ball screw shaft 71. Moreover, the protection pipe 120A according to the second embodiment can achieve an effect according to the effect of the protection pipe 120 according to the first embodiment.

  Since the protective pipe 120A is formed with the slit 121, the protective pipe 120A has an elastic force that expands in the direction in which the slit 121 extends in the circumferential direction. For this reason, the protective pipe 120A is inserted into the insertion hole 11a in a reduced diameter state, and is fixed inside the insertion hole 11a by elastic recovery. Thereby, even if the outer diameter D1 of the protection pipe 120A is not equal to the inner diameter D2 of the insertion hole 11a, the protection pipe 120A can be fitted into the insertion hole 11a.

  Further, the inner peripheral surface of the insertion hole 11a is exposed at a portion corresponding to the slit 121 of the protective pipe 120A. That is, since the slit 121 becomes a recess on the inner peripheral surface of the protective pipe 120A, the slit 121 functions as a grease reservoir. Thereby, the smooth movement of the steady rest mechanism 110 is maintained in the slit 121 over a long period of time, and the components of the steady rest mechanism 110 (the steady rest mechanism main body 111 and the elastic member 112) are prevented from being worn. it can. As a result, the tip end portion 71c of the ball screw shaft 71 is stably supported on the inner peripheral surface of the insertion hole 11a of the rod 11 for a long period of time, so that the tip portion 71c of the ball screw shaft 71 is effectively swung around. Can be suppressed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited by the said embodiment etc.

  In the above embodiment, cylindrical protective pipes 120 and 120A are fitted into the insertion hole 11a. However, the present invention is not limited thereto, and the inner peripheral surface of the insertion hole 11a may be formed as a coating layer by being coated as a protective layer. Further, the protective pipes 120 and 120A may be manufactured by performing coating processing on the inner peripheral surface of an arbitrary pipe-shaped material. In addition, as long as it is a process which reduces the friction coefficient (micro | micron | mu) 2 between the elastic member 112 and the insertion hole 11a, not only a coating process, another processing method may be used.

  In the first embodiment, the slide portion 31 is a ball circulation type in which the ball 50 smoothly moves on the base 60 by rolling on the guide rails 63R and 63L. However, the invention is not limited to this, and other than the ball circulation type may be used. For example, the slide part 31 may move directly on the base 60 without the ball 50 interposed therebetween.

(Modification 1)
Moreover, in the said 1st Embodiment, the protection pipe 120 is formed from one member. However, like the protection pipe 120B shown in FIG. 13A, for example, the protection pipe 120B may be composed of a divided body 130 divided into a plurality of pieces along the Y-axis direction. Specifically, each of the protection pipes 120B is obtained by dividing the protection pipe 120. By adjusting the number of divided bodies 130 to be inserted into the insertion hole 11a of the rod 11, the protection pipe 120B can be protected even if the length in the Y-axis direction is not equal to the length of the insertion hole 11a in the Y-axis direction. 120B can be inserted into the insertion hole 11a.

(Modification 2)
In the second embodiment, the protective pipe 120A is formed from one member. However, like the protection pipe 120C shown in FIG. 13B, for example, the protection pipe 120C may be configured of a divided body 130 divided into a plurality along the Y-axis direction. Specifically, each of the protection pipes 120C is obtained by dividing the protection pipe 120A. By adjusting the number of divided bodies 130 inserted into the insertion hole 11a of the rod 11, the protective pipe 120C can be protected even if the length in the Y-axis direction of the protective pipe 120C is not equal to the length of the insertion hole 11a in the Y-axis direction. 120C can be inserted into the insertion hole 11a. Furthermore, by arranging the divided bodies 130 so that the positions of the slits 121 on the XZ plane change between the adjacent divided bodies 130, the grease reservoirs of the slits 121 can effectively function. Specifically, the protective pipe 120C has slits 121 formed at a plurality of positions in the XZ plane. For this reason, when the slits 121 formed at a plurality of positions in the XZ plane come into contact with the elastic member 112 of the steadying mechanism 110, grease can be supplied more evenly to the outer periphery of the elastic member 112.

(Modification 3)
Further, as in the protective pipe 120D shown in FIG. 13C, each of the divided bodies 130 may be formed with a protrusion 123 protruding in the Y-axis direction. Thereby, when inserting the division body 130 in the insertion hole 11a, the clearance gap 124 can be formed between each of the division bodies 130. FIG. In the gap 124, the inner peripheral surface of the insertion hole 11a is exposed. That is, the gap 124 functions as a grease reservoir because it becomes a recess on the inner peripheral surface of the protective pipe 120D.

  Moreover, in the said embodiment, the protection pipes 120 and 120A were formed in the cylindrical shape. However, the design is not limited to the cylindrical shape, and the design can be arbitrarily changed according to the shape of the insertion hole 11a of the rod 11 or the shape of the steadying mechanism 110.

  Moreover, in 2nd Embodiment, the slit 121 of 120 A of protection pipes is formed in linear form. For example, even if the slit 121 is formed in a spiral shape around the Y axis, an effect according to the effect of the protective pipe 120A can be obtained.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention, and do not limit the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Actuator 11 Rod 11a Insertion hole 12 Rod main body 13 Tip metal fitting 18 Cover 19 Bolt 20 Motor unit 21 Motor 22 Motor housing 23 Output shaft (rotary shaft)
24 Actuator cable 25 Bolt 30 Guide device 31 Slide portion 32 Slide portion main body 32a Through hole 32b Female thread portion 40 Rolling body storage unit 41 Rolling body circulation path 50 Ball 60 Base 61 Bottom plate portion 62R, 62L Side wall portion 63R, 63L Guide rail 70 Ball Screw 71 Ball screw shaft 71a Ball screw shaft main body 71b Locking groove 71c Tip 72 Ball screw nut 73 Connecting member 74 Bolt 80 Front housing 82 Oilless bearing 90 Rear housing 92 Ball bearing 110 Stabilizing mechanism 111 Stabilizing mechanism main body 111a Through Hole 111b Air hole 111c Groove 112 Elastic member 113 Locking member 120, 120A, 120B, 120C, 120D Protection pipe (protection part)
121 Slit 122 Grease Reservoir 123 Projection 124 Clearance 130 Divided Body S Space

Claims (10)

A motor with a rotating shaft;
A ball screw having a ball screw shaft that rotates together with the rotational motion of the rotational shaft, and a ball screw nut that moves linearly with the rotational motion of the ball screw shaft;
A slide portion fixed to the ball screw nut and moving linearly with the ball screw nut;
A rod fixed to the slide portion, linearly moving with the ball screw nut and the slide portion, and having an insertion hole for inserting a tip of the ball screw shaft;
An anti-sway mechanism that is attached to the tip of the ball screw shaft and suppresses the whirling of the ball screw shaft;
A protective portion that covers the inner peripheral surface of the insertion hole of the rod and contacts the steadying mechanism;
An actuator comprising:   At least the inner peripheral surface of the protection portion has a first friction coefficient between the protection portion and the steady stop mechanism, and the steady stop mechanism when the steady stop mechanism contacts the inner peripheral surface of the insertion hole. The actuator according to claim 1, wherein the actuator is made of a material smaller than a second friction coefficient between the insertion hole and the insertion hole.   2. The actuator according to claim 1, wherein at least an inner peripheral surface of the protection part is a smooth surface having a lower roughness than an inner peripheral surface of the insertion hole.   The actuator according to any one of claims 1 to 3, wherein the protective portion is a substantially cylindrical member having an outer diameter substantially equal to an inner diameter of the rod.   5. The actuator according to claim 4, wherein a cross section perpendicular to the axial direction of the rod is formed in an O shape in the protection portion which is the substantially cylindrical member.   The protective portion, which is a substantially cylindrical member, has a C-shaped cross section perpendicular to the axial direction of the rod by forming slits connecting both ends of the rod in the axial direction. The actuator according to claim 4.   The actuator according to claim 6, wherein the protection portion has an elastic force that increases a diameter in a direction in which the slit expands.   The actuator according to any one of claims 4 to 7, wherein the protection unit is configured by a plurality of divided bodies that are divided along an axial direction of the rod.   4. The actuator according to claim 1, wherein the protection part is a coating layer formed by coating an inner peripheral surface of the insertion hole of the rod. 5.   The actuator according to any one of claims 1 to 9, wherein a material of the protection part is made of a fluororesin.

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