JP5627220B2 - Actuator - Google Patents

Description

  The present invention relates to an actuator.

  Conventionally, an actuator using a ball screw has been widely used as a mechanism for reciprocating a member linearly. For example, the actuator disclosed in Patent Document 1 is configured to reciprocate the slider linearly along the guide rail by rotating a ball screw shaft by an electric motor.

JP 2001-227614 A

  However, since the above-described actuator has the ball screw shaft exposed to the outside, for example, when foreign matter such as dust enters the ball screw, the accuracy of the ball screw deteriorates and the slider does not move. There is a possibility that problems will occur. On the other hand, there is a possibility that abrasion dust may be generated when the ball screw nut moves on the ball screw shaft, which is not suitable for use in a clean room or the like.

  Therefore, an object of the present invention is to provide an actuator that can be preferably used even in a bad environment or in a clean room.

  The actuator according to the present invention has a space extending in the axial direction inside, a guide rail formed with an elongated hole for communicating the space and the outside, and the guide rail moves on the guide rail while being guided by the guide rail. A slider, a ball screw shaft installed in the space of the guide rail, a ball screw nut screwed with the ball screw shaft through a plurality of balls, and the slider and the ball screw nut are connected through the elongated hole. And a connecting member.

  As described above, in the actuator according to the present invention, the guide rail has a space inside, and the ball screw shaft and the ball screw nut are installed in the space to be blocked from the outside. For this reason, even when used in an environment where foreign matters such as dust are likely to adhere, foreign matter does not adhere to the ball screw shaft and the ball screw nut, and it can be used even in adverse environments. On the contrary, since the slight wear dust generated when the ball screw nut moves on the ball screw shaft is not released to the outside, it can be preferably used even in a clean room. When the actuator is operated, a drive source for rotating the ball screw shaft around the axis is installed.

  The actuator can take various configurations. For example, the actuator further includes a spacer installed between the slider and the ball screw nut in the elongated hole, and the connecting member connects the slider and the ball screw nut via the spacer. It is preferable that it is comprised. Thus, by interposing a spacer between the slider and the ball screw nut, the ball screw nut is not lifted to the slider side even when the slider and the ball screw nut are tightened excessively by the connecting member. As a result, it is possible to prevent a problem that the ball screw shaft into which the ball screw nut is screwed is warped. In addition, it is preferable that the thickness of this spacer is the same dimension as the depth of the long hole.

  Moreover, it is preferable that the said long hole is covered with the slider. By covering the elongated hole with the slider in this way, the inside and outside of the guide rail can be surely blocked, and as a result, entry of foreign matter into the guide rail can be reliably prevented.

  The ball screw nut has a ball holding portion for housing a plurality of balls with the ball screw shaft on the first end side in the axial direction, and a connected portion for connecting the connecting member in the axial direction. It is preferable to have a configuration such that it is provided on the end portion side of 2. Thus, by dividing the ball screw nut into the ball holding portion and the connected portion along the axial direction, it is possible to prevent the connecting member from interfering with the ball of the ball screw.

  In addition, the said ball | bowl holding | maintenance part and a to-be-connected part can also be comprised by another member. In this case, a receiving recess is formed in the connected portion, and the ball holding portion is received and fixed in the receiving recess.

  The actuator according to the present invention can be used without any problem even in a bad environment or in a clean room.

FIG. 1 is a plan view of an actuator according to the present embodiment. FIG. 2 is a front view of the actuator according to the present embodiment. FIG. 3 is a right side view of the actuator according to the present embodiment. FIG. 4 is a left side view of the actuator according to the present embodiment. FIG. 5 is a bottom view of the actuator according to the present embodiment. 6 is a cross-sectional view taken along line AA in FIG. FIG. 7 is a plan view showing a state where the electric motor is attached to the actuator according to the present embodiment. FIG. 8 is a partial cross-sectional view showing another embodiment of the ball screw nut.

  Embodiments of an actuator according to the present invention will be described below with reference to the drawings. In the following description, the horizontal direction in FIG. 1 is referred to as the axial direction, and the vertical direction is referred to as the width direction.

  As shown in FIGS. 1 to 6, the actuator 1 includes a guide rail 2 and a slider 3 that moves on the guide rail 2 along the axial direction. A ball screw shaft 4 is installed in the internal space S in the guide rail 2, and a ball screw nut 5 is screwed to the ball screw shaft 4 via a plurality of balls (not shown). The ball screw shaft 4, the ball screw a nut 5, and a plurality of balls constitute a so-called ball screw. Further, since the slider 3 and the ball screw nut 5 are connected by the connecting member 6, they are interlocked. Hereinafter, each member will be described in detail.

  The guide rail 2 is formed in a tubular shape so as to define a space S extending in the axial direction. A convex rail portion 21 extending in the axial direction is formed at the center in the width direction of the upper surface of the guide rail 2. The rail portion 21 is formed with a long long hole 22 in the central portion in the axial direction of the upper surface, and the long hole 22 is configured as a through hole so as to communicate the internal space with the outside. The rail portion 21 has ball grooves 23 formed on both side surfaces extending in parallel with the axial direction. The right end portion of the space S of the guide rail 2 is sealed by a sealing member 24 made of, for example, metal or resin. Further, the guide rail 2 has a coupling accommodating portion 25 that accommodates the coupling 12 that couples the electric motor 13 and the ball screw shaft 4 at the left end.

  The slider 3 is installed on the guide rail 2 so as to move in the axial direction along the rail portion 21 of the guide rail 2. The size of the slider 3 is designed to cover the elongated hole 22 of the guide rail 2, and the elongated hole 22 is covered by the slider 3 even when the slider 3 moves to the right end portion or the left end portion. It is in the state. In addition, the slider 3 has a recess 31 extending in the axial direction on the lower surface, and the rail portion 21 of the guide rail 2 is accommodated in the recess 31. A ball groove 32 extending in the axial direction is formed on each of both side surfaces defining the recess 31. The ball groove 32 of the slider 3 extends in parallel along the ball groove 23 of the guide rail 2, and a plurality of balls are held between the ball grooves 23, 32, so that a so-called circulation type linear bearing is configured. Has been. By rolling the plurality of balls, the frictional force when the slider 3 moves on the rail portion 21 can be reduced. The circulating ball bearing is configured to circulate along the inside of the slider 3 and the ball groove 32. Further, a through hole for passing a bolt 6 described later is formed on the upper surface of the slider 3.

  As shown in FIG. 6, a ball screw shaft 4 extending in the axial direction is installed in the internal space S of the guide rail 2. The ball screw shaft 4 has a spiral groove formed on the side surface, and the left end portion is supported by the guide rail 2 via a ball bearing 11. The ball screw shaft 4 is rotated by an electric motor 13 to be described later, so that the ball screw nut 5 screwed into the ball screw shaft 4 moves forward and backward in the space S in the axial direction.

  The ball screw nut 5 is screwed onto the ball screw shaft 4 via a plurality of balls. The ball screw nut 5 has a tubular shape, and the left half is a ball holding portion 51 and the right half is a connected portion 52. The ball holding portion 51 has a spiral groove formed on the inner surface thereof, and holds a plurality of balls between the groove and the spiral groove of the ball screw shaft 4. The connected portion 52 does not hold a ball like the ball holding portion 51, and a screw hole 521 for screwing with a bolt 6 described later is formed on the upper surface. Thus, the problem that the bolt 6 interferes with the ball when the bolt 6 is screwed can be prevented by not holding the ball in the connected portion 52 where the bolt 6 is screwed.

  The connecting member 6 is constituted by two bolts 6 in this embodiment. The ends of the two bolts 6 are screwed into the screw holes 521 of the connected portion 52 of the ball screw nut 5 so as to connect the slider 3 and the ball screw nut 5. A spacer 7 is installed in the long hole 22 between the slider 3 and the ball screw nut 5. The spacer 7 has substantially the same thickness as the depth of the long hole 22, that is, the thickness of the upper surface of the rail portion 21 of the guide rail 2. As a result, even if the bolt 6 is overtightened, the ball screw nut 5 is not lifted upward due to the presence of the spacer 7, and as a result, the ball screw shaft 4 can be prevented from warping upward.

  In the actuator 1 configured as described above, as shown in FIG. 7, an electric motor (drive source) 13 is connected to the left end portion of the ball screw shaft 4 via a coupling 12. Then, by actuating the electric motor 13, the ball screw shaft 4 is rotated through the coupling 12, and a ball screw nut 5 that is screwed onto the ball screw shaft 4 through a plurality of balls is moved forward and backward along the ball screw shaft 4. Let When the ball screw nut 5 moves back and forth in the axial direction, the slider 3 connected to the ball screw nut 5 also moves on the guide rail 2 in the axial direction in conjunction with the movement of the ball screw nut 5.

  As described above, according to the actuator 1 according to the present embodiment, since the ball screw shaft 4 and the ball screw nut 5 constituting the ball screw are housed inside the guide rail 2, foreign matters such as dust do not adhere to the ball screw. It can be used even in adverse environments. On the contrary, even if wear dust is generated when the ball screw nut 5 moves on the ball screw shaft 4, it is not released to the outside, so that it can be used even in a clean room.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change is possible unless it deviates from the meaning of this invention.

  For example, in the above embodiment, the bolt 6 is exemplified as the connecting member, but various connecting members may be used as long as the slider 3 and the ball nut 5 can be connected so that the slider 3 is interlocked with the ball nut 5. be able to.

  Further, although the right end portion of the ball shaft 4 is not supported, the right end portion of the ball screw shaft 4 may be supported.

  Further, the ball screw nut 5 according to the above embodiment is configured as one member. However, as shown in FIG. 8, the ball holding portion 51 and the connected portion 52 may be configured as separate members. In this case, the coupled portion 52 is formed with an accommodation recess 522 for accommodating the ball holding portion 51 in addition to a through hole for passing the ball screw shaft 4. The method for fixing the ball holding portion 51 and the connected portion 52 to each other is not particularly limited. For example, the ball holding portion 51 and the connected portion 52 may be fixed by forming a key and a key groove, or may be fixed by a bolt or the like. Can do.

  Further, the linear bearing may be either a rolling motion or a sliding motion.

DESCRIPTION OF SYMBOLS 1 Actuator 2 Guide rail 21 Rail part 3 Slider 4 Ball screw shaft 5 Ball screw nut 51 Ball holding part 52 Connected part 6 Bolt (connection member)
7 Spacer S Space

Claims (2)

A guide rail having a space extending in the axial direction inside, and having an elongated hole that communicates the space with the outside;
A slider that is guided by the guide rail and moves on the guide rail;
A ball screw shaft installed in the space of the guide rail;
A ball screw nut screwed to the ball screw shaft via a plurality of balls;
A connecting member for connecting the slider and the ball screw nut through the elongated hole,
Regardless of the position of the slider on the guide rail, the entire slot is covered with the slider ,
The ball screw nut has a tubular shape, and a first end portion in the axial direction is a ball holding portion that holds a plurality of balls between the ball screw shaft and a second end portion in the axial direction is the connecting member. Actuator as a connected part for connecting the two . A spacer installed between the slider and the ball screw nut in the elongated hole;
The actuator according to claim 1, wherein the connecting member connects the slider and the ball screw nut via the spacer.

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