TW201604445A - Ball screw device - Google Patents

Abstract

Provided is a ball screw device for reducing runout of the end part of a screw shaft even when the screw shaft is under an excessive load. To achieve this, a ball screw device (1) has a screw shaft (10) having a helical groove (11) formed in the surface thereof, a bearing (20) and an enlarged-diameter member (50) for supporting a bearing installation part (10a) formed in the end part of the screw shaft (10), and a spacer (60). The enlarged-diameter member (50) comes in contact with an end surface with which the helical groove (11) is interconnected, forming an annular shape that can be divided in the axial direction into a plurality of divisions. The spacer (60), which covers at least part of the enlarged-diameter member (50), is fitted in between the axial end surface of the enlarged-diameter member (50) and an inner ring (21) of the bearing (20).

Description

Ball screw device

The present invention relates to a ball screw device, and more particularly to a ball screw device including a ball screw and a bearing for supporting a screw shaft thereof, which is used in various working machines such as a single-axis actuator.

Conventionally, a ball screw device including a ball screw and a bearing that supports both end portions or one end portion of the screw shaft has been known for use in various working machines such as a single-axis actuator (Patent Document 1). In the above ball screw device, generally, the outer peripheral surface of the screw shaft is reduced in diameter to form a bearing installation portion to be fitted to the inner peripheral surface of the bearing inner ring, and a spacer is inserted between the end surface of the bearing installation portion and the bearing. And fastened with anti-loose nuts.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2009-162314, No. 1

Here, the form of the screw shaft of the ball screw device is such that the spiral groove formed on the surface thereof is formed and not formed on the end surface of the bearing installation portion.

As shown in Fig. 8(a), the screw shaft 100 in which the spiral groove 101 is not formed to the end surface 102a of the bearing installation portion 102 is as shown in Fig. 8(b), and the shape of the end surface 102a is formed into a uniform annular shape. Therefore, as shown in Fig. 8(c), the inner ring 111 of the bearing 110 can be held by the spacer 130 and the end surface 102a disposed between the lock nut 120 and the inner ring 111 of the bearing 110, and the bearing 110 is restrained toward Axial movement.

On the other hand, as shown in Fig. 9(a), the screw shaft 200 formed so that the spiral groove 201 is formed to the end surface 202a of the bearing installation portion 202 is as shown in Fig. 9(b), and the shape of the end surface 202a is uneven. Ring shape. This shape is remarkable when the groove pitch of the spiral groove 201 is small (when the rising angle of the spiral groove 201 is small), and the exposed portion of the bottom portion 201a of the spiral groove 201 is generated. The screw shaft 200 of the above embodiment is shown in Fig. 9(c), by a spacer 230 disposed between the lock nut 220 and the inner ring 211 of the bearing 210, and an inner ring provided at the end face 202a and the bearing 210. The spacer 240 between the 211 limits the axial movement of the bearing 210 holding the inner ring 211.

As described above, since the radial dimension of the end surface 202a of the screw shaft 200 abutting against the inner ring 211 of the bearing 210 or the spacer 240 is not uniform, a non-uniform annular shape is formed, which is fastened by the anti-loose nut 220. Occasionally, the spacer 240 will invade the spiral groove 201 beyond the end surface 202a, or The end of the screw shaft 200 becomes more susceptible to vibration when an excessive load is applied to the screw shaft 200.

When the ball screw device is operated in the above state, deformation, eccentricity, or inclination of the screw shaft 200 is caused, and as a result, the end portion of the screw shaft 200 is bent by the fastening of the lock nut 220, or relative to It is difficult to provide a pulley or a coupling at the end of the screw shaft 200, and thus there is room for further study.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a ball screw device which can reduce the vibration of the end portion of the screw shaft even when an excessive load is applied to the screw shaft.

A ball screw device for solving the above problems is a screw shaft having a spiral groove formed on a surface thereof, and a bearing supporting a bearing installation portion formed at an end portion of the screw shaft thereof, and an end face communicating with the spiral groove is provided a ring-shaped diameter-expanding member that can be divided into a plurality of divided bodies in the axial direction, and has at least a portion covering the enlarged diameter member, and is fitted into the axial end surface of the enlarged diameter member and the bearing Spacer between the circles.

Further, in the ball screw device, it is preferable that the spacer covers the bearing installation portion side of the diameter-expanding member, and is fitted between the axial end surface of the diameter-expanding member and the inner ring of the bearing.

Further, in the above-described ball screw device, the above-described diameter expansion structure is provided in a region in the axial direction in which a cross-sectional area of the projection of the end surface is enlarged in a peripheral direction. The pieces are better.

Further, in the ball screw device described above, the spacer is preferably divided into a plurality of divided bodies in the axial direction, and the divided bodies and the divided bodies of the expanded diameter members are integrally formed integrally.

Other aspects of the ball screw device for solving the above-described problems include: a screw shaft having a spiral groove forming portion having a spiral groove and a projection formed on a surface thereof, and a bearing installation portion supported by the bearing, and a bearing supporting the above In the bearing installation portion, a first tapered portion in which the projection is gradually reduced in diameter from the spiral groove forming portion toward the bearing installation portion is formed in the spiral groove forming portion, and an inner peripheral surface is provided in the first tapered portion. The fitting ring-shaped spacer has an axial end surface of the spacer abutting against the inner ring of the bearing. Further, in the above ball screw device, the spacer is preferably such that the inner diameters of the both end portions are the same in the axial direction.

Further, in the ball screw device, the second tapered portion having the diameter of the inner diameter of both end portions is formed on the inner peripheral surface of the spacer so as to reduce the diameter of the projection, and at least one portion of the second tapered portion is formed in the axial direction. It is better.

According to the state of the present invention, it is possible to provide a ball screw device which can reduce the vibration of the end portion of the screw shaft even when an excessive load is applied to the screw shaft.

1‧‧‧Ball screw device

10‧‧‧ Screw shaft

10a‧‧‧ Bearing Setting Department

10b‧‧‧Spiral groove formation

10c‧‧‧1st tapered section

11‧‧‧Spiral groove

12‧‧‧ protrusion

13‧‧‧Reducing section

13a‧‧‧ end face

20‧‧‧ bearing

21‧‧‧ inner circle

50‧‧‧Expanding members

60‧‧‧ spacers

70‧‧‧ spacers

71‧‧‧Clock Department

72‧‧‧2nd inclined taper

Fig. 1 is a view showing the configuration of the first embodiment of the ball screw device.

Fig. 2 is a view showing a process of installing the diameter-expanding member of the first embodiment of the ball screw device.

Fig. 3 is a view showing the configuration of the second embodiment of the ball screw device.

Fig. 4 is a view showing a process of installing the diameter-expanding member of the second embodiment of the ball screw device.

Fig. 5 is a view showing the configuration of a third embodiment of the ball screw device.

Fig. 6 is a view showing the configuration of a fourth embodiment of the ball screw device.

Fig. 7 is a view showing the configuration of a fifth embodiment of the ball screw device.

Fig. 8 is a view showing the configuration of a conventional ball screw device, wherein (a) is a right side view of the screw shaft, (b) is a front view of the screw shaft, and (c) is a cross-sectional view taken along the axial direction of the ball screw device.

Fig. 9 is a view showing the configuration of a conventional ball screw device, wherein (a) is a right side view of the screw shaft, (b) is a front view of the screw shaft, and (c) is a cross-sectional view taken along the axial direction of the ball screw device.

The following detailed description is intended to provide a description of the particular embodiments of the invention. However, it is extremely clear that more than one embodiment can be implemented without the specific details described above. In other instances, well-known structures and devices are shown in the drawings.

Hereinafter, an embodiment of the ball screw device of the present invention will be described with reference to the drawings.

(First embodiment)

Fig. 1 is a view showing a configuration of a first embodiment of a ball screw device, wherein (a) is a left side view of the screw shaft, (b) is a partial cross-sectional view of the screw shaft, and (c) is a shaft along the ball screw device. A cross-sectional view of the direction. Moreover, Fig. 2 is a view showing a process of installing the diameter-expanding member of the first embodiment of the ball screw device.

As shown in Fig. 1(c), the ball screw device 1 has a screw shaft 10 of a ball screw and a plurality of series of rolling bearings 20 and 20 that support the end of the screw shaft 10. A spiral groove 11 is formed on the surface of the screw shaft 10. The rolling bearing 20 has two inner rings 21, 21 that are fitted to the bearing installation portion 10a formed at the end of the screw shaft 10 and rotate integrally with the screw shaft 10, and are passed through a plurality of rollings on the outer periphery of the inner rings 21, 21. The body 22 is provided with an outer ring 23 that freely rotates to support the inner ring 21.

Further, the ball screw device 1 includes a cylindrical casing 30 that houses the rolling bearing 20, and the outer peripheral surface of the rolling bearing 20 (the outer peripheral surface of the outer ring 23) is slidably fitted to the inner peripheral surface of the casing 30.

The inner ring 21 of the rolling bearing 20 is formed at the stage of the screw shaft 10 The portion 12 and the lock nut 40 are positioned at predetermined positions. The lock nut 40 is bolted to the end of the screw shaft 10, and a spacer 41 is provided on the periphery of the screw shaft 10 between the lock nut 40 and the inner ring 21. The spacer 41 is made of, for example, a coil spring or a coil spring or a metal having a longitudinal elastic modulus.

Here, in the bearing installation portion 10a of the screw shaft 10, as shown in Fig. 1(a), a ring-shaped diameter-expanding member 50 is fitted. One end surface 50a of the diameter-expanding member 50 is in contact with the end surface 13a. The diameter-expanding member 50 can be divided into a plurality of divided bodies 50A in the axial direction (see FIG. 2(b)).

In addition, a spacer is provided on the outer peripheral surface of the diameter-expanding member 50. 60 is formed with a step portion 61 that covers at least a portion of the diameter-expanding member 50 and is engaged with the end surface of the diameter-enlarged member 50 in the axial direction (the end surface opposite to the end surface 50a of the end surface 13a) 50b. The end face 50b forms the step portion 12. Further, the spacer 60 may cover at least a portion of the side of the bearing installation portion 10a of the diameter-expanding member 50.

The spacer 60 is fitted to the periphery of the screw shaft 10 between the end surface 50b and the inner ring 21. That is, the inner ring 21 of the rolling bearing 20 is pressed against the end surface 50b by the fastening force of the anti-loose nut 40. The spacer 60 is made of, for example, a coil spring or a coil spring or a metal of longitudinal elastic modulus.

Next, the manufacture of the screw shaft 10 constructed as above Process description. First, as shown in the second (a) to (c), the side of the spiral groove 11 of the bearing installation portion 10a in which the screw shaft 10 is formed is inserted into two or more divided bodies 50A and 50B. The diameter expanding member 50. Further, in the second (b) diagram, the diameter-expanding member 50 is divided into two. Here, the outer diameter of the diameter-expanding member 50 (the divided body 50A) is smaller than the inner circumference of the bearing 20 The inner diameter of 21 is much larger.

Next, as shown in the second (b) and (c), the spacer 60 having the inner peripheral surface shape of the end surface 50b that is engaged with the diameter-expanding member 50 (the divided body 50A) is fitted to the inner circumference of the bearing 20. Between 21 (see Figure 1(c)). In other words, as shown in Fig. 1(c), the end surface 60a on the bearing installation portion 10a side of the gap 60 is fitted between the inner ring 21 of the bearing 20 and the end surface 50b of the diameter-expanding member 50 (divided body 50A), and is restricted. The axial movement of the bearing 20.

Similarly to the diameter-expanding member 50, the spacer 60 is divided into a plurality of divided bodies in the axial direction, and the divided bodies and the divided body 50A of the expanded diameter member 50 may be integrally formed.

(Second embodiment)

Fig. 3 is a view showing a configuration of a second embodiment of the ball screw device, wherein (a) is a left side view of the screw shaft, (b) is a front view of the screw shaft, and (c) is a partial sectional view of the screw shaft, ( d) is a cross-sectional view along the axial direction of the ball screw device. Moreover, Fig. 4 is a view showing a process of installing the diameter-expanding member of the second embodiment of the ball screw device.

As shown in Fig. 3(d), the ball screw device 1 has a screw shaft 10 of a ball screw and a plurality of series of rolling bearings 20 and 20 that support the end of the screw shaft 10. A spiral groove 11 is formed on the surface of the screw shaft 10. The rolling bearing 20 has two inner rings 21 and 21 which are fitted to the bearing installation portion 10a formed at the end of the screw shaft 10 and integrally rotate with the screw shaft 10, and are provided with perforations on the outer periphery of the inner rings 21 and 21, respectively. Multiple rolling elements 22 freely rotates to support the outer ring 23 of the inner ring 21.

Further, the ball screw device 1 is provided with a rolling bearing 20 The cylindrical casing 30 and the outer peripheral surface of the rolling bearing 20 (the outer peripheral surface of the outer ring 23) are slidably fitted to the inner peripheral surface of the casing 30.

The inner ring 21 of the rolling bearing 20 is positioned at a predetermined position with the stage portion 12 formed of the screw shaft 10 and the lock nut 40. The lock nut 40 is bolted to the end of the screw shaft 10, and a spacer 41 is provided on the periphery of the screw shaft 10 between the lock nut 40 and the inner ring 21. The spacer 41 is made of, for example, a coil spring or a coil spring or a metal having a longitudinal elastic modulus.

Here, in the bearing installation portion 10a of the screw shaft 10, as described 3(a) shows that the reduced diameter portion 13 which communicates with the spiral groove 11 and is reduced in diameter in a predetermined direction in the axial direction is formed. The reduced diameter portion 13 is provided to enlarge (increase) the sectional area of the projection 11a of the end surface 13a across the peripheral direction so as not to impair the strength of the screw shaft 10.

Further, in the reduced diameter portion 10, as shown in the third (b) and (c), a ring-shaped diameter-expanding member 50 is fitted. One end surface 50a of the diameter-expanding member 50 abuts against the end surface 13a of the reduced diameter portion 13. The diameter-expanding member 50 can be divided into a plurality of divided bodies 50A in the axial direction (see FIG. 4(b)).

In addition, a spacer is provided on the outer peripheral surface of the diameter-expanding member 50. 60 is formed with a step portion 61 that covers at least a portion of the diameter-expanding member 50 and is engaged with the end surface of the diameter-enlarged member 50 in the axial direction (the end surface opposite to the end surface 50a of the end surface 13a) 50b. The end face 50b forms the step portion 12.

The spacer 60 is fitted between the end surface 50b and the inner ring 21 The periphery of the screw shaft 10. That is, the inner ring 21 of the rolling bearing 20 is pressed against the end surface 50b by the fastening force of the anti-loose nut 40. The spacer 60 is made of, for example, a coil spring or a coil spring or a metal of longitudinal elastic modulus.

Next, the manufacture of the screw shaft 10 constructed as above Process description. First, as shown in the fourth (a) to (c), the spiral groove 11 is formed on the side of the spiral groove 11 of the bearing installation portion 10a in which the screw shaft 10 is formed, and is formed in the axial direction by a cutting method or the like. The reduced size portion 13 of a predetermined size. At this time, the end surface 13a that communicates with the spiral groove 11 is formed by the reduced diameter portion 13, and the diameter of the diameter of the bearing portion 10a toward the diameter of the reduced diameter portion 13 is reduced so that the area of the end face 13a subjected to the axial load is changed. Big. Further, the amount of cutting when the reduced diameter portion 13 is formed is cut to a smaller diameter than the bottom of the spiral groove 11 so as not to impair the strength of the screw shaft 10.

Next, the reduced diameter portion 13 is embedded and divided into two or more points. The diameter-expanding member 50 formed by the cutting bodies 50A and 50B. Further, in the fourth (b) diagram, the diameter-expanding member 50 is divided into two. Here, the axial dimension of the diameter-expanding member 50 (the divided body 50A) is preferably a size substantially equal to the axial direction of the reduced diameter portion 13. Moreover, it is preferable that the inner diameter dimension of the diameter-expanding member 50 (the divided body 50A) is substantially equal to the outer diameter dimension of the reduced diameter portion. Further, the outer diameter of the diameter-expanding member 50 (the divided body 50A) is preferably larger than the inner diameter of the inner ring 21 of the bearing 20.

Next, as shown in the fourth (b) and (c), the spacer 60 having the inner peripheral surface shape of the end surface 50b that is engaged with the diameter-expanding member 50 (the divided body 50A) is fitted to the inner ring of the bearing 20. Between 21 (see Figure 3(d)). That is, as shown in Figure 3(d), the spacer 60 is The end surface 60a on the bearing installation portion 10a side is fitted between the inner ring 21 of the bearing 20 and the end surface 50b of the diameter-expanding member 50 (divided body 50A) to restrict the axial movement of the bearing 20.

Here, the spacer 60 is the same as the diameter-expanding member 50, and is axially The divided bodies are divided into a plurality of divided bodies, and the divided bodies and the divided bodies 50A of the expanded diameter members 50 may be integrally formed.

As described above, the reduced diameter portion 13 of the screw shaft 10 increases the area of the end surface 13a that receives the load, and the diameter-increasing member 50 is assembled to the reduced diameter portion 13 to reduce the vibration of the end portion of the screw shaft 10.

Further, the screw shaft 10 constructed as described above can be used for a trapezoidal thread in addition to the ball screw device.

(Third embodiment)

Fig. 5 is a view showing a configuration of a third embodiment of the ball screw device, wherein (a) is a cross-sectional view along the axial direction of the ball screw device, (b) is a perspective view of the screw shaft, and (c) is a view showing the screw. A side view of the shaft assembly spacer, (d) is a left side view of the screw shaft.

As shown in Fig. 5(a), the ball screw device 1 has a screw shaft 10 and a plurality of series of rolling bearings 20 and 20 that support the end of the screw shaft 10. The screw shaft 10 is configured as a bearing installation portion 10a and a spiral groove forming portion 10b in the axial direction. A spiral groove 11 is formed on the surface of the spiral groove forming portion 10b of the screw shaft 10. The rolling bearing 20 has two inner rings 21, 21 that are fitted to the bearing installation portion 10a formed at the end of the screw shaft 10 and rotate integrally with the screw shaft 10. Passing through a plurality of outer circumferences of the inner rings 21, 21 The rolling bodies 22 are respectively provided with outer rings 23 that freely rotate to support the inner ring 21.

Further, the ball screw device 1 is provided with a rolling bearing 20 The cylindrical casing 30 and the outer peripheral surface of the rolling bearing 20 (the outer peripheral surface of the outer ring 23) are slidably fitted to the inner peripheral surface of the casing 30.

The inner ring 21 of the rolling bearing 20 is positioned at a predetermined position with the projection 12 formed on the screw shaft 10 and the lock nut 40. The lock nut 40 is bolted to the end of the screw shaft 10, and a spacer 41 is provided on the periphery of the screw shaft 10 between the lock nut 40 and the inner ring 21. The spacer 41 is made of, for example, a coil spring or a coil spring or a metal having a longitudinal elastic modulus.

Also, in the screw shaft 10, as shown in the fifth (a), (b) chart As shown, a ring-shaped spacer 70 is provided.

The spacer 70 is fitted to the periphery of the screw shaft 10 between the end surface of the end portion 70a and the inner ring 21. That is, the inner ring 21 of the rolling bearing 20 is pressed against the end surface of the end portion 70a by the fastening force of the loose nut 40. The spacer 70 is made of, for example, a coil spring or a coil spring or a longitudinal elastic modulus metal (iron, non-ferrous) or the like or a resin.

[beveled taper]

As shown in Fig. 5(c), the spiral groove forming portion 10b of the screw shaft 10 is formed with the step portion 13 from the boundary portion between the bearing installation portion 10a and the spiral groove forming portion 10b toward the spiral groove forming portion 10b. The first tapered tapered portion 10c whose diameter is gradually increased in the axial direction is gradually increased. The first tapered portion 10c is provided such that the projection 12 is gradually reduced in diameter from the spiral groove forming portion 10b toward the bearing installation portion 10a.

On the other hand, in the inner peripheral surface 70c of the spacer 70, as shown in Fig. 5(c), the engaging portion 71 engaged with the bearing installation portion 10a and the first tapered portion 10c of the screw shaft 10 are formed. The second tapered tapered portion 72 is fitted. In other words, the engaging portion 71 is a portion that is formed in a shape that is engaged with the step portion 13 of the boundary portion between the bearing installation portion 10a and the spiral groove forming portion 10b and the inner peripheral surface of the bearing installation portion 10a. Further, an end surface of the axial end portion 70a of the spacer 70 abuts against the inner ring 21 of the bearing 20.

Here, the second tapered tapered portion 72 is formed corresponding to the shape of the first tapered tapered portion 10c of the screw shaft 10. For example, in the fifth (c) diagram, in the cross-sectional shape along the axial direction of the spacer 70, the inclination angle θ of the second oblique tapered portion 72 with respect to the axial direction of the spacer 70 is set at substantially the same angle and relative to The inclination angle θ of the first tapered tapered portion 10c in the axial direction of the screw shaft 10.

Next, the screw shaft 10 constructed as above is manufactured. Process description. As shown in Fig. 5(c), the screw shaft 10 is inserted into the bearing installation portion 10a of the screw shaft 10 from the side opposite to the spiral groove forming portion 10b in the direction of the second tapered portion 72 and the engaging portion 71. Opposite cylindrical shaped spacers 70. The second tapered tapered portion 72 is press-fitted into the first tapered tapered portion 10c and fitted, and the spacer 70 is fixed to the screw shaft 10.

Here, in the ball screw device of the present embodiment, the spacer 70 is firmly fixed to the screw shaft 10 by the fitting of the second tapered tapered portion 72 and the first tapered tapered portion 10c. Therefore, the first oblique taper portion 10c and the end surface of the step portion 13 are equally subjected to an excessive axial load, and the vibration of the end portion of the screw shaft 10 can be reduced.

Furthermore, the screw shaft 10 constructed above can be used for ball screw It can also be used for trapezoidal threads in addition to the rod device.

(Fourth embodiment)

Next, the fourth embodiment of the ball screw device will be described with reference to the drawings. 6(a) and 6(b) are views showing a configuration of a fourth embodiment of the ball screw device, and a left side view corresponding to the fifth (c) and (d). The ball screw device 1 of the present embodiment has the same configuration as that of the first embodiment except that the inner peripheral surface 70c of the spacer 70 is different. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted or simplified, and the different configurations will be mainly described.

As shown in Fig. 6(a), the ball screw of this embodiment The device is a first tapered tapered portion 10c having an inclination angle θ formed on the screw shaft 10 in the same manner as in the first embodiment. Further, the inner peripheral surface 70c of the spacer 70 fitted to the first tapered tapered portion 10c is formed by combining the inclination angle θ of the first tapered tapered portion 10c so that the inner diameter of one end portion 70a is the same as the other The second tapered portion 72 of the inner diameter of the end portion 70b is monotonically expanded. In other words, the second tapered portion 72 that is monotonously reduced in diameter along the axial direction of the other end portion 70b and the inner diameter of the one end portion 70a is formed on the inner peripheral surface 70c of the spacer 70. That is, the engaging portion 71 is not provided in the spacer 70 used in the ball screw device of the present embodiment. As described above, in the spacer 70, the engaging portion 71 may or may not be provided. Moreover, when the engaging portion 71 is provided, the axial forming range is appropriately set depending on the use of the ball screw device or the like.

When the above spacer 70 is assembled to the screw shaft 10, as in the sixth (b) shows that the spacer 70 is a bearing set than the first embodiment. The portion 10a is further provided on the side of the spiral groove forming portion 10b for reference, and the spacer 70 can be more firmly fixed to the screw shaft 10.

(Fifth Embodiment)

Next, the fifth embodiment of the ball screw device will be described with reference to the drawings. 7(a) and 7(b) are views showing a configuration of a fifth embodiment of the ball screw device, and a right side view corresponding to the first (c) and (d) views. The ball screw device 1 of the present embodiment has the same configuration as that of the first embodiment except that the first tapered tapered portion 10c and the inner peripheral surface 70c of the spacer 70 are different. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted or simplified, and the different configurations will be mainly described.

As shown in Fig. 7(a), the ball screw of this embodiment Unlike the first embodiment, the first inclined tapered portion 10c having an inclination angle ψ (ψ<θ) is formed in the screw shaft 10. Further, the inner circumferential surface 70c of the spacer 70 fitted to the first tapered tapered portion 10c has the same inner diameter dimension at one end portion in the axial direction and the inner diameter dimension of the other end portion. That is, the spacers 70 used in the ball screw device of the present embodiment are not provided with the second tapered portion 72.

When the above-described spacer 70 is assembled to the screw shaft 10, as shown in Fig. 7(b), the spacer 70 is provided shallower in the bearing setting portion than the spiral groove forming portion 10b as compared with the first embodiment. On the side 10a, the elastic force of the spacer 70 against the inner ring 21 can be made stronger. And between The inner peripheral surface 70c of the spacer 70 does not need to be processed by the second tapered portion 72, and the manufacturing cost can be reduced.

The invention has been described with reference to the specific embodiments thereof, but the description is not intended to limit the invention. The description of the present invention will be apparent to those skilled in the art from the various modifications of the embodiments and the embodiments of the invention. Therefore, the scope of the patent application is to be construed as being limited by the scope and the scope of the invention.

1‧‧‧Ball screw device

10‧‧‧ Screw shaft

10a‧‧‧ Bearing Setting Department

11‧‧‧Spiral groove

11a‧‧‧dun

12‧‧‧ protrusion

13a‧‧‧ end face

20‧‧‧ bearing

21‧‧‧ inner circle

22‧‧‧ rolling elements

23‧‧‧Outer ring

30‧‧‧Shell

40‧‧‧Safety nuts

41‧‧‧ spacers

50‧‧‧Expanding members

50a‧‧‧ end face

50b‧‧‧ end face

60‧‧‧ spacers

61‧‧‧ Stage Department

Claims (8)

A ball screw device comprising: a screw shaft having a spiral groove formed on a surface thereof; and a bearing supporting a bearing installation portion formed at an end portion of the screw shaft thereof, and an end surface communicating with the spiral groove is abutted, An annular-shaped diameter-expanding member that can be divided into a plurality of divided bodies in the axial direction, and has at least a portion covering the enlarged-diameter member, and is fitted between an axial end surface of the enlarged diameter member and an inner ring of the bearing Spacer. The ball screw device according to claim 1, wherein the spacer covers the bearing installation portion side of the diameter-expanding member, and is fitted between an axial end surface of the diameter-expanding member and an inner ring of the bearing. . The ball screw device according to the first or second aspect of the invention, wherein the diameter-expanding member is provided in a region in the axial direction in which a cross-sectional area of the projection of the end surface is enlarged in a peripheral direction. The ball screw device according to the first or second aspect of the invention, wherein the spacer is divided into a plurality of divided bodies in the axial direction, and the divided bodies and the divided body of the expanded diameter member are integrally formed. . The ball screw device according to claim 3, wherein the spacer is divided into a plurality of divided bodies in the axial direction, and the divided bodies and the divided bodies of the expanded diameter members are integrally formed. A ball screw device comprising: a screw shaft having a spiral groove forming portion having a spiral groove and a protrusion formed on a surface thereof, a bearing installation portion supported by the bearing, and a bearing supporting the bearing setting portion, In the spiral groove forming portion, a first tapered portion in which the protruding portion is gradually reduced in diameter from the spiral groove forming portion toward the bearing installation portion is formed, and a circle in which the inner peripheral surface is fitted in the first tapered portion is formed. In the ring-shaped spacer, the axial end surface of the spacer abuts against the inner ring of the bearing. The ball screw device according to claim 6, wherein the spacer has an inner diameter of both end portions having the same diameter in the axial direction. The ball screw device according to claim 6, wherein the inner peripheral surface of the spacer is formed by a second tapered portion in which the diameter of the inner diameter of both end portions is reduced in accordance with the diameter of the projection. At least a portion of the axial direction.