JP6620529B2 - Ball screw - Google Patents

Description

  The present invention relates to a ball screw, and more particularly to a ball screw provided with a spacer between adjacent nuts.

In a ball screw used by being incorporated in a machine tool, an injection molding machine, a semiconductor manufacturing apparatus, or the like, it is generally performed to improve rigidity by applying a preload to ensure axial positioning accuracy. .
Patent Document 1 discloses a method of providing a preload by providing a flat spacer between two adjacent nuts. Further, in Patent Document 2, spacers having piezoelectric sheets alternately attached to both surfaces are interposed between two adjacent nuts, and elastic deformation occurs in the spacers when strongly sandwiched between the two nuts. In addition, it has been proposed to adjust the preload freely from the outside by adjusting the voltage supplied to the piezoelectric sheet from the outside.

JP 2009-204141 A Japanese Patent No. 2876614

  By the way, with a ball screw, the preload gradually decreases due to wear deterioration that occurs with the lapse of operating time, and finally falls into a preload loss state. If the preload of the ball screw is released, the ball screw will not be rigid enough, resulting in poor positioning accuracy and problems with the processing accuracy of the device incorporating the ball screw. Become. In order to restore the apparatus, it is necessary to arrange a new ball screw and to replace the ball screw. For this reason, in order to prepare for a sudden stop of the device, the ball screw must be stocked. If there is no stock, the device must be stopped until a new ball screw arrives.

In the ball screw described in Patent Document 1, it is possible to adjust the preload from the outside, and the preload can be constantly adjusted to a constant level. It is necessary to provide a driving device for supplying a voltage, or to provide a biasing means including a fluid pressure source, a fluid pressure supply path, a pressure chamber, and the like, and the preload adjustment cannot be performed by the ball screw alone.
Accordingly, the present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide a ball screw capable of restoring the preload when the preload is lowered or the preload is lost.

  In order to achieve the above object, a ball screw according to one aspect of the present invention includes a screw shaft having a first spiral groove 11 provided on an outer peripheral surface, and a second spiral groove formed on each inner peripheral surface. A plurality of balls that roll on a ball rolling path formed by a first spiral groove and a second spiral groove; And a spacer disposed between the first nut and the second nut so as to apply a first preload to the ball in the road. The spacer includes a preload applying mechanism that applies a second preload to the balls in the ball rolling path, separately from the first preload.

  With the ball screw according to one aspect of the present invention, it is possible to restore the preload when a decrease in the preload or a preload loss occurs.

In the ball screw concerning Embodiment 1 of the present invention, it is an important section sectional view showing an internal structure of a screw portion. It is a figure which shows the internal structure of a spacer in the ball screw which concerns on Embodiment 1 of this invention. In FIG. 2, it is a figure which shows the state which removed the connection fixing member. In the ball screw concerning Embodiment 2 of the present invention, it is an important section sectional view showing an internal structure of a screw part. It is a figure which shows the internal structure of a spacer in the ball screw which concerns on Embodiment 2 of this invention. It is principal part sectional drawing which expands and shows a part of FIG. In FIG. 5, it is a figure which shows the state which removed the connection fixing member.

  Hereinafter, a ball screw according to an embodiment of the present invention will be described with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments of the present invention, and the repetitive description thereof is omitted. In FIGS. 2 and 5, a cover member to be described later is not shown for easy viewing of the drawings.

(Embodiment 1)
As shown in FIGS. 1 and 2, the ball screw 1 according to the first embodiment of the present invention includes a screw shaft 10 having a first spiral groove on the outer peripheral surface and respective inner peripheral surfaces through which the screw shaft 10 passes. The second spiral groove 15 is provided with two nuts 14 (first nut 14A and second nut 14B) provided so as to face the first spiral groove 11. The screw shaft 10 and the two nuts 14 are arranged coaxially so that the outer peripheral surface of the screw shaft 10 and the inner peripheral surfaces of the two nuts 14 face each other. Each of the two nuts 14 is screwed to the screw shaft 10 in a series arrangement so as to be adjacent to each other.

In addition, the ball screw 1 according to the first embodiment of the present invention includes a plurality of balls 18 that roll in a ball rolling path 17 formed by the first spiral groove 11 and the second spiral groove 15. The ball rolling path 17 is individually formed in each of the two nuts 14.
Further, the ball screw 1 according to the first embodiment of the present invention has two nuts (a first nut 14A and a second nut) so as to apply an initial preload as a first preload to the ball 18 in the ball rolling path 17. 14B) A spacer 20 is provided between the four spacers 14.
Furthermore, although not shown, the ball screw 1 according to the first embodiment of the present invention includes a ball return path that circulates the ball 18 by connecting both ends of the ball rolling path 17. Also in this ball return path, similarly to the ball rolling path 17, each of the two nuts 14 is provided individually.

In the two nuts 14, the first nut 14 </ b> A is configured by a cylindrical body provided with a flange portion 16 at one end, and is opposed to the first spiral groove 11 of the screw shaft 10 on the inner peripheral surface of the cylindrical body. A spiral groove 15 is provided. The second nut 14B is configured by a cylindrical body in which the flange portion 16 is omitted as compared with the first nut 14A, and the second nut 14B is opposed to the first spiral groove 11 of the screw shaft 10 on the inner peripheral surface of the cylindrical body. A spiral groove 15 is provided.
As shown in FIG. 1, the plurality of balls 18 are disposed in the ball rolling path 17 and are disposed in the ball return path, although not shown. That is, the ball screw 1 of the first embodiment has an endless ball circulation path formed by the ball rolling path 17 and the ball return path, and a plurality of balls 18 circulate in the ball circulation path. ing. This endless ball circulation path is also formed for each nut 14.

  The first spiral groove 11 of the screw shaft 10 has a Gothic arc shape in which the cross-sectional shape perpendicular to the extending direction of the first spiral groove 11 is a substantially V shape in which two identical arcs having different centers of curvature are combined. Also, in each of the second spiral grooves 15 of the two nuts 14, a Gothic arc whose cross-sectional shape perpendicular to the extending direction of the second spiral grooves 15 is a substantially V shape combining two identical arcs with different centers of curvature. It is made into a shape. Each of the two nuts 14 is disposed so that the second nut 14B is adjacent to the flange 16 of the first nut 14A on the opposite side.

In the ball screw 1, the ball 18 moves around the screw shaft 10 while moving in the ball rolling path 17, and reaches the end point of the ball rolling path 17, where the ball rolling path 17 and one of the ball return paths. Enter the end. The ball 18 that has entered the ball return path passes through the ball return path, reaches the other end of the ball return path, and returns to the starting point of the ball rolling path 17 from there.
Therefore, in the ball screw 1, when the screw shaft 10 and the two nuts 14 are relatively rotated, the screw shaft 10 and the two nuts 14 are moved through the rolling of the ball 18 in the ball rolling path 17. It moves relative to the central axis. Since the ball 18 circulates infinitely in the endless circulation path, the screw shaft 10 and the two nuts 14 can continuously move relative to each other.

As shown in FIGS. 1 and 2, the spacer 20 includes a preload applying mechanism 20 </ b> A that applies a preload as a second preload to the balls 18 in the ball rolling path 17 separately from the initial preload. As shown in FIG. 2, the preload imparting mechanism 20A includes a first fixing plate 21 located on one first nut 14A side and a second second nut 14B side located on the other second nut 14B side. And a fixed plate 22.
The preload imparting mechanism 20 </ b> A includes a disc spring 23 disposed between the first fixed plate 21 and the second fixed plate 22. The preload applying mechanism 20 </ b> A includes a connection fixing member 24 that is fixed by connecting the first fixing plate 21 and the second fixing plate 22 in a state where a certain amount of load is applied to the disc spring 23. The connection fixing member 24 is detachably fixed to the first fixing plate 21 and the second fixing plate 22, and is fastened and fixed by, for example, a fastening mechanism combining a male screw and a female screw.
As shown in FIG. 1, the spacer 20 includes a cover member 26 that covers the preload applying mechanism 20 </ b> A along the circumferential direction of the nut 14, but the cover member 26 is not shown in FIG. 2. Yes.

Each of the 1st and 2nd fixing plates 21 and 22 is comprised by the cylindrical shape by which the through-hole which the screw shaft 10 penetrates was provided in the center part. The disc spring 23 is provided with a through hole through which the screw shaft 10 penetrates at the center, and has a disk-shaped conical shape with the center protruding beyond the peripheral edge. The disc spring 23 applies a load to the upper central portion and the lower peripheral portion of the conical shape, and obtains a spring action by bending the conical height in a direction in which the conical height decreases.
For example, four disc springs 23 are arranged in series in the central axis direction of the screw shaft 10. Of the four disc springs 23, the two disc springs 23 positioned first and second from the first fixed plate 21 side are loaded when a load is applied to the upper central portion and the lower peripheral portion of the conical shape. It arrange | positions so that a center part may bend to the 1st stationary plate 21 side. On the other hand, the two disc springs 23 positioned first and second from the second fixed plate 22 side have a central portion when the load is applied to the upper central portion and the lower peripheral portion of the conical shape. It arrange | positions so that it may bend to 22 side.

  The disc spring 23 positioned first from the first fixed plate 21 side is arranged so that at least the peripheral edge is in contact with the first fixed plate 21. The disc spring 23 positioned first from the second fixed plate 22 side is arranged so that at least the peripheral edge is in contact with the second fixed plate 22. The two disc springs 23 positioned between the first disc spring 23 on the first fixing plate 21 side and the first disc spring 23 on the second fixing plate 22 side have respective peripheral portions along the circumferential direction. The disc spring guide member 25 is used for fixing. That is, the four disc springs 23 act as springs when a load is applied to the first fixed plate 21 and the second fixed plate 22 in the direction in which the distance between the first fixed plate 21 and the second fixed plate 22 becomes narrower. Are arranged so that can be obtained. Each of the four disc springs 23 is held in a state in which bending is ensured in each of the first fixing plate 21 and the second fixing plate 22.

In the first embodiment, four disc springs 23 are provided, but the number is not limited to this, and one or more may be provided. Further, the four disc springs 23 may be configured as one disc spring group, and two or more disc spring groups may be provided.
The preload applying mechanism 20A configured as described above connects and fixes the connection fixing member 24 from the first fixing plate 21 and the second fixing plate 22 as shown in FIG. The disc spring 23 is released by removing the member 24 and releasing the holding state, and a new preload is applied to the balls 18 in the ball rolling paths 17 of the two nuts 14 by the repulsive force of the disc spring 23. Can do. Similar to the initial preload, the repulsive force of the disc spring 23 applies a predetermined preload in the tensile direction to the ball 18 in the ball rolling path 17 so that the ball 18 in the ball rolling path 17 is in a two-point contact state. Give.

The two nuts 14 are fixed to each other by a nut fixing key (not shown) that extends over the two nuts 14 with the spacer 20 disposed between the two nuts 14. The two nuts 14 are spaced from both sides so as to apply a predetermined initial preload in the pulling direction to the balls 18 in the ball rolling path 17 so that the balls in the ball rolling path 17 are in a two-point contact state. The seat 20 is fixed in a tightened state. At this time, the spacer 20 is held between the two nuts 14 by a nut fixing key for fixing the two nuts 14. Further, in the preload applying mechanism 20 </ b> A of the spacer 20, the disc spring 23 does not work, and the preload by the disc spring 23 is not applied to the ball 18 in the ball rolling path 17.
A plurality of nut fixing keys and connection fixing members 24 are arranged so as to be scattered in the circumferential direction of the nut 14. The nut fixing key and the connecting fixing member 24 are arranged so as not to overlap each other.

Next, effects of the ball screw 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
When mounting the first nut 14 </ b> A and the second nut 14 </ b> B on the screw shaft 10, first, the first nut 14 </ b> A is screwed onto the screw shaft 10 via the ball 18.
Next, the screw shaft 10 is inserted into the through hole of the spacer 20 from the end opposite to the first nut 14A side, and the end surface of the spacer 20 on the first fixing plate 21 side is the flange of the first nut 14A. It is made to contact the end surface on the opposite side to the part 16 side.

  Next, the second nut 14 </ b> B is screwed onto the screw shaft 10 from the end of the screw shaft 10 opposite to the first nut 14 </ b> A via the ball 18. The end face of the second nut 14B on the first nut 14A side is brought into contact with the end face of the spacer 20 on the second fixing plate 22 side and tightened, and the first nut 14A and the second nut 14B are nut-fixed in this tightened state. Connect and fix with a key. Thus, a predetermined initial preload in the tensile direction is applied to the ball 18 in the ball rolling path 17 so that the ball 18 in the ball rolling path 17 is in a two-point contact state. At this time, the disc spring 23 does not work in the preload applying mechanism 20A of the spacer 20, and the preload by the disc spring 23 is not applied to the balls 18 in the ball rolling paths 17 of the two nuts 14, respectively. .

Thus, by adopting a double nut configuration in which the two nuts 14 are mounted on the screw shaft 10 so as to be adjacent to each other, the rigidity can be increased as compared with the case of a single nut, and the feed system using the ball screw 1 is used. The positioning accuracy can be improved.
Here, the ball screw 1 of the first embodiment is used by being incorporated in a machine tool, an injection molding machine, a semiconductor manufacturing apparatus or the like that requires positioning accuracy. In the ball screw 1 used in such an environment, foreign matters such as chips and wear powder enter the first spiral groove 11 of the screw shaft 10 and the second spiral groove 15 of each of the two nuts 14 during driving. easy.

When foreign matter such as chips or wear powder enters the first spiral groove 11 or the second spiral groove 15, the foreign matter is between the first spiral groove 11 and the ball 18 or between the second spiral groove 15 and the ball 18. The first spiral groove 11, the second spiral groove 15, the ball 18, and the like are worn and the preload is lowered, and finally the preload is lost.
At this time, the ball screw 1 of the first embodiment includes a preload applying mechanism 20A that applies preload separately from the initial preload, and as shown in FIG. 3, the first fixing plate 21 and the second fixing plate 22 are provided. The disc spring 23 is released by releasing the connection fixing member 24 from the disc and releasing the holding state, and a new preload is applied to the balls 18 in the ball rolling paths 17 of the two nuts 14 by the repulsive force of the disc spring 23. Can be granted. That is, the ball screw 1 of the first embodiment can restore the preload applied to the ball 18 in the ball rolling path 17 even when the initial preload is reduced or the initial preload is lost. Moreover, since the ball screw 1 of Embodiment 1 can newly apply a preload to the balls 18 in the ball rolling paths 17 of the two nuts 14 by removing the connecting and fixing member 24, the preload is restored. Therefore, it is possible to restore the preload without providing a drive unit for the outside.

The ball screw 1 according to the first embodiment can be continuously used by restoring the preload by the repulsive force of the disc spring 23 even when the preload is lost.
When this preload restoring operation is performed, a new ball screw 1 is prepared, and until the new ball screw 1 is delivered, rigidity is secured by preload due to the repulsive force of the disc spring 23, and the feed system The feed system can be operated while maintaining the positioning accuracy.
Then, when a new ball screw 1 is delivered, the drive of the feed system is stopped, and an operation of replacing the deteriorated ball screw 1 with a new ball screw 1 is performed. Thereby, the mechanism of the feed system can be updated, and the stop time of the feed system can be shortened, so that the reduction in production can be minimized.

In addition, there is no need to stock new ball screws 1 on the manufacturing side or at the production site that uses machine tools, injection molding machines, semiconductor manufacturing equipment, etc. that incorporate the ball screw 1, thereby reducing inventory costs. Can contribute. That is, the ball screw 1 of Embodiment 1 can improve the convenience compared with the conventional ball screw.
As described above, according to the ball screw 1 according to the first embodiment of the present invention, it is possible to restore the preload when the initial preload is reduced or dropped.

(Embodiment 2)
As shown in FIGS. 4 and 5, the ball screw 2 according to the second embodiment of the present invention has substantially the same configuration as the ball screw 1 of the first embodiment, and includes a screw shaft 10 and a screw shaft 10. , Two nuts (first nut 14A and second nut 14B) 14, a plurality of balls 18 rolling in the ball rolling path 17, and a spacer 20 disposed between the two nuts 14. It has. And the ball screw 2 of Embodiment 2 adjusts the preload given to the ball 18 in each ball rolling path 17 of each of the two nuts 14 by the preload applying mechanism 20B of the spacer 20 as shown in FIG. A preload application adjusting mechanism 30 is further provided.

Similar to the first embodiment, the spacer 20 includes a preload applying mechanism 20B that applies a second preload to the ball 18 in the ball rolling path 17 separately from the initial preload as the first preload. As shown in FIG. 5, the preload applying mechanism 20B has substantially the same configuration as the preload applying mechanism 20A according to the first embodiment. However, the preload applying mechanism 20B is replaced with the first fixing plate 21 shown in FIG. Is provided with a first fixing plate 21B. That is, the preload applying mechanism 20B includes a first fixing plate 21B, a second fixing plate 22, four disc springs 23, and a plurality of connection fixing members 24.
The first fixing plate 21B has substantially the same configuration as the first fixing plate 21, but unlike the first fixing plate 21, it enters the inside of the first nut 14A at the end on the first nut 14A side. The step is provided with a step. The first nut 14A of the second embodiment, unlike the first nut 14A of the first embodiment, have the projecting portion 35 which projects from the end opposite to the first fixing plate 21 B to the first fixing plate 21 B-side are doing.

A plurality of preload application adjusting mechanisms 30 are arranged so as to be scattered in the circumferential direction of the first nut 14A. This preload application adjusting mechanism 30 is also arranged so as not to overlap with the nut fixing key.
As shown in FIG. 6, the preload application adjusting mechanism 30 is provided at an end portion of the first fixing plate 21 </ b > B facing the first nut 14 </ b > A, and the central direction of the first nut 14 </ b > A (the central axial direction of the screw shaft 10). Or a pressing member 33 having a second inclined surface 32 that is inclined in the same direction as the first inclined surface 31 and is in contact with the first inclined surface 31. Yes. Further, the preload application adjusting mechanism 30 includes a screw portion 34 that moves the pressing member 33 in the radial direction of the first nut 14A.

The pressing member 33 is formed in a trapezoidal shape around which the second inclined surface 32 makes a round. In the second embodiment, the second inclined surface 32 is inclined so that, for example, the width of the upper portion on the screw portion 34 side of the pressing member 33 is wider than the width of the lower portion on the opposite side to the screw portion 34 side. With the inclination of the second inclined surface 32, the first inclined surface 31 is inclined so as to approach the first nut 14A as the screw shaft 10 is approached, for example.
The second inclined surface 32 may be inclined such that the width of the upper portion of the pressing member 33 on the screw portion 34 side is narrower than the width of the lower portion on the opposite side to the screw portion 34 side. As the second inclined surface 32 is inclined, the first inclined surface 31 may be inclined so as to be separated from the first nut 14 </ b> A as it approaches the screw shaft 10.

The threaded portion 34 is screwed into a female threaded portion formed so as to penetrate the protruding portion 35 of the first nut 14A along the radial direction of the first nut 14A, and the pressing member 33 is connected to the tip. The threaded portion 34, times the second inclined surface 32 is clockwise when viewed from the outer peripheral side of the first nut 14A in contact with the first inclined surface 31 of the first fixed plate 21 B of the pressing member 33 By moving, the pressing member 33 is moved to the central axis side in the radial direction of the first nut 14A. Also, threaded portion 34, the second inclined surface 32 is the counterclockwise direction as viewed from the outer peripheral side of the first nut 14A in contact with the first inclined surface 31 of the first fixed plate 21 B of the pressing member 33 By rotating, the pressing member 33 is moved to the outer peripheral side in the radial direction of the first nut 14A.

  Like the ball screw 1 of the first embodiment described above, the ball screw 2 of the second embodiment includes a preload applying mechanism 20B that applies a preload separately from the initial preload. The disc spring 23 is released by removing the coupling fixing member 24 from the fixing plate 21B and the second fixing plate 22 to release the holding state, and a new preload is applied to the ball in the ball rolling path 17 by the repulsive force of the disc spring 23. 18. That is, also in the ball screw 1 of the second embodiment, when the initial preload is reduced or the initial preload is lost, the balls 18 in the ball rolling paths 17 of the two nuts 14 (14A, 14B) The preload to be applied can be restored.

  Further, the ball screw 2 of the second embodiment includes a preload application adjusting mechanism 30. In the preload application adjusting mechanism 30, the pressing member 33 moves toward the central axis in the radial direction of the first nut 14A by rotating the screw portion 34 in the clockwise direction when viewed from the outside of the first nut 14A. . The first fixing plate 21B is pushed toward the second fixing plate 22 by the movement of the pressing member 33, the repulsive force of the disc spring 23 is increased, and the preload applied to the ball 18 in the ball rolling path 17 is increased. To increase. Further, the preload application adjusting mechanism 30 rotates the screw portion 34 in the counterclockwise direction when viewed from the outside of the first nut 14A, whereby the pressing member 33 moves to the outer peripheral side in the radial direction of the first nut 14A. To do. Then, by the movement of the pressing member 33, the first fixing plate 21B is pushed to the side opposite to the second fixing plate 22 side (first nut 14A side) by the repulsive force of the disc spring 23, and the repulsive force of the disc spring 23 is increased. The preload applied to the ball 18 in the ball rolling path 17 is reduced. Therefore, in the ball screw 2 of the second embodiment, the preload imparting adjusting mechanism 30 can adjust the pressurization imparted to the balls 18 in the ball rolling paths 17 of the two nuts 14 by the preload imparting mechanism 20B. .

Further, the ball screw 2 of the second embodiment is a screw of the preload application adjusting mechanism 30 even when the preload applying mechanism 20B has applied too much preload to the balls 18 in the ball rolling paths 17 of the two nuts 14. The preload can be reduced by rotating in the counterclockwise direction when viewed from the outer peripheral side of the portion 34 nut 14 (by loosening).
In the second embodiment, the case where the preload application adjusting mechanism 30 is provided on the first nut 14A side has been described. However, the preload application adjusting mechanism 30 may be provided on the second nut 14B side. In this case, the second fixing plate 22 is configured to have a step so as to enter the second nut 14 </ b> B, and the first inclined surface 31 is provided on the second fixing plate 22. And the protrusion part 35 is provided in the edge part by the side of the 2nd fixing plate 22 of 2nd nut 14B.

In the second embodiment, the case where the preload applied to the ball 18 in the ball rolling path 17 is reduced by rotating the screw portion 34 in the counterclockwise direction when viewed from the outer peripheral side of the nut 14 will be described. However, the preload applied to the ball 18 in the ball rolling path 17 may be reduced by rotating the screw portion 34 in the clockwise direction when viewed from the outer peripheral side of the nut 14. In short, it is only necessary that the distance between the two fixing plates can be changed by the rotation of the screw portion 34 after the connection fixing member 24 is removed.
The present invention has been specifically described above based on the above embodiment, but the present invention is not limited to the above embodiment, and it is needless to say that various changes can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Ball screw 10 ... Screw shaft 11 ... 1st spiral groove 14A ... 1st nut 14B ... 2nd nut 15 ... 2nd spiral groove 16 ... Flange part 17 ... Ball rolling path 18 ... Ball 20 ... Spacer 20A, 20B ... Preload application mechanism 21 ... First fixing plate 22 ... Second fixing plate 23 ... Belleville spring 24 ... Connection fixing member 25 ... Belleville spring guide member 26 ... Cover member 30 ... Preload application adjusting mechanism 31 ... First inclined surface 32 ... First 2 inclined surfaces 33 ... pressing member 34 ... threaded portion 35 ... protruding portion

Claims (2)

A screw shaft provided with a first spiral groove on the outer peripheral surface;
A first nut and a second nut provided with a second spiral groove on each inner peripheral surface facing the first spiral groove and through which the screw shaft passes;
A plurality of balls rolling on a ball rolling path formed by the first spiral groove and the second spiral groove;
A spacer disposed between the first nut and the second nut so as to apply a first preload to the ball in the ball rolling path;
With
The spacer includes a preload application mechanism that applies a second preload to the ball in the ball rolling path, separately from the first preload.
A preload application adjusting mechanism that adjusts a preload applied to the ball in the ball rolling path by the preload application mechanism is provided in either the first nut or the second nut .
The preload application mechanism is:
A first fixing plate located on the first nut side;
A second fixing plate located on the second nut side;
A disc spring disposed between the first fixed plate and the second fixed plate;
A connection fixing member fixed by connecting the first fixing plate and the second fixing plate in a state where a certain amount of load is applied to the disc spring;
The preload application adjusting mechanism includes:
A first inclined surface provided at an end of the first fixed plate and the second fixed plate facing the nut and inclined with respect to a central axis direction of the nut;
A pressing member having a second inclined surface inclined in the same direction as the first inclined surface and in contact with the first inclined surface;
A threaded portion for moving the pressing member in the radial direction of the nut;
Ball screw and said that you have with a.   The ball screw according to claim 1, wherein the connection fixing member is detachably fixed to the first fixing plate and the second fixing plate.

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