JP2003269565A - Ball screw device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable ball screw device at low costs. <P>SOLUTION: This ball screw device is provided with a screw shaft having a spiral screw groove on its outer circumferential surface, a ball nut having a screw groove corresponding to the screw groove of the screw shaft on its inner circumferential surface and a ball return passage penetrated in an axial direction, and loosely fitted to the screw shaft, a circulating piece 18, having a ball circulating passage 21 communicating the screw grooves and the ball return passage, and fitted and fixed to both end faces of the ball nut, a large number of balls interposed in a circulating manger while rolling in the screw grooves, the ball return passage and the ball circulating passage 21. A belt-like fixed piece 30 extended in a peripheral direction of the ball nut is formed on an end face side of the ball nut of the circulating piece 18, and a recessed part corresponding to this fixed piece 30 is formed in the ball nut. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball screw device used in, for example, industrial machines.

[0002]

2. Description of the Related Art A conventional ball screw device of this type has a thread groove having a semicircular cross section on its outer peripheral surface and extending axially, and a thread groove having a semicircular cross section on its inner peripheral surface. The ball nut is fitted. The screw groove of the ball nut and the screw groove of the screw shaft face each other to form a spiral passage between them, and a large number of balls as rolling elements are rollably loaded in the spiral passage. ing. The ball nut (or the screw shaft) is linearly moved by the rotation of the ball by the rotation of the screw shaft (or the nut).

By the way, when the ball nut moves linearly, the ball moves while rolling in a spiral passage formed by both screw grooves, but in order to continuously move the ball nut, It is necessary to make the ball circulate infinitely. As a method for infinitely circulating the balls, a type that circulates by connecting with a tube such as a ball circulation tube type, or forms a ball return passage that penetrates the ball nut in the axial direction and forms a notch on the end surface of the ball nut. Then, a circulating top having a ball circulating path for communicating the ball returning passage with the screw grooves in the notch (ball circulating member)
There is a type in which an infinite circulation passage of a ball is formed by fitting and screwing and fixing, and thereby, the both screw grooves, the ball return passage and the ball circulation passage.

[0004]

However, in the above-mentioned conventional ball screw device, since the circulating spinning top as the ball circulating component is fixed to the end of the ball nut by screwing, the ball nut needs to be tapped. In addition, there is a problem that the screwing work with a screw driver is troublesome and the manufacturing cost is high. The present invention has been made in order to eliminate such inconvenience, and an object of the present invention is to provide a ball screw device having low cost and high reliability.

[0005]

In order to achieve the above object, the invention according to claim 1 provides a screw shaft having a spiral screw groove on the outer peripheral surface, and a screw groove corresponding to the screw groove of the screw shaft. A ball nut that has a ball return passage penetrating in the axial direction and has a ball return passage that penetrates in the axial direction, and a ball circulation passage that connects the both screw grooves and the ball return passage. Ball-shaped ball circulating member fitted and fixed to both end surfaces of the ball nut, and a large number of balls rotatably interposed while rolling in the screw grooves, the ball return passage and the ball circulation passage. In the ball screw device including the above, a protrusion is provided at a portion of the ball circulating member that comes into contact with the radially inner surface of the ball nut, and a recess corresponding to the protrusion is provided on the radially inner surface of the ball nut. Features .

According to a second aspect of the present invention, in the first aspect, an elastic protrusion that elastically presses and contacts the inner surface of the ball circulating member is provided at a portion of the ball circulating member that contacts the radially inner surface of the ball nut. And The invention according to claim 3 has a screw shaft having a spiral screw groove on the outer peripheral surface, a screw groove corresponding to the screw groove of the screw shaft on the inner peripheral surface, and a ball return passage penetrating in the axial direction. And a ball nut loosely fitted to the screw shaft, and a ball-shaped ball fitted and fixed to both end faces of the ball nut, having a ball circulation path that connects the screw grooves and the ball return path. A ball screw device comprising: a circulation member; and a plurality of balls that are circulated while rolling in the screw grooves, the ball return passage, and the ball circulation passage, the ball nut of the ball circulation member. A strip-shaped or ring-shaped fixing member extending in the circumferential direction of the ball nut is provided on the end face side of the ball nut, and a recess corresponding to the fixing member is provided in the ball nut.

According to a fourth aspect of the present invention, in the third aspect, a protrusion is provided at a portion of the ball circulating member that comes into contact with the radially inner surface of the ball nut, and the radially inner surface of the ball nut corresponds to the protrusion. It is characterized in that a concave portion is provided. The invention according to claim 5 is the invention according to claim 3 or 4.
In the above, the strip-shaped fixing member has an inverse taper shape that widens toward the bottom of the recess, and the recess has a shape corresponding to the inverse taper shape.

According to a sixth aspect of the present invention, in any one of the third to fifth aspects, the elasticity of the ball circulating member elastically presses and contacts the inner surface of the ball nut in the radial direction. It is characterized in that a protrusion is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially broken schematic view for explaining a ball screw device which is an example of an embodiment of the present invention, FIG. 2 is a left side view of FIG. 1 (a view seen from an end face side of a ball nut), FIG. 3 is a diagram showing a circulating top provided with a strip-shaped fixing piece, (b) is a front view, (a) is a left side view of (b),
(C) is a right side view of (b).

As shown in FIGS. 1 and 2, the ball screw device 10 has a screw shaft 13 extending in the axial direction with a thread groove 12 having a semicircular cross section on the outer peripheral surface and a half cross section on the inner peripheral surface. A ball nut 16 having a circular thread groove 14 is fitted. The screw groove 14 of the ball nut 16 and the screw groove 12 of the screw shaft 13 face each other to form a spiral passage between them, and a large number of balls 15 as rolling elements roll in the spiral passage. It is movably loaded.

The screw shaft 13 (or the ball nut 1)
By rotating 6), the ball nut 16 (or the screw shaft 1
3) moves linearly through the rolling of the ball 15. A ball return passage 17 penetrating in the axial direction is bored in the wall portion of the ball nut 16, and a cutout 19 into which a circulating top 18 shown in FIG. 3 is fitted is formed on the end surface of the ball nut. The return passage 17 and the screw grooves 12 and 14 are formed so as to communicate with each other.

As shown in FIG. 3, the circulating top 18 has a tongue portion 2 for scooping up the balls 15 of both screw grooves 12 and 14.
0, the ball return passage 17 and the screw grooves 12, 1
4 is provided with a curved ball circulation groove (ball circulation passage) 21 which communicates with each other. The ball circulation groove 21, the screw grooves 12, 14 and the ball return passage 17 allow the ball 15 to move infinitely. It forms a circulation passage. Here, in this embodiment, the ball nut 16 is provided on the end surface side (the right side in FIG. 3B) of the ball nut 16 of the circulating top 18.
A band-shaped fixing piece (fixing member) 30 extending in the circumferential direction is provided, and a recess 31 corresponding to the fixing piece 30 is provided on the end surface of the ball nut 16 as shown in FIG.

Then, the circulating top 18 is fitted into the notch 19 and the fixing piece 30 provided on the circulating top 18 is fitted into the recess 31, so that the circulating top 18 is fitted to the end portion of the ball nut 16. In this fixed state, the circulating piece 18 is fitted by fitting the fixing piece 30 into the recess 31.
Is restrained in the axial direction, the radial direction and the circumferential direction to prevent the axial direction and the radial direction from slipping off and prevent the circumferential rotation. As a method for fitting and fixing the fixing piece 30 in the recess 31, there is a simple fitting, but in addition to this, for example, press-fitting, bonding, or both press-fitting and bonding can be adopted.

As described above, in this embodiment, the circulating top 18 is fitted into the notch 19 and the fixing piece 30 provided on the circulating top 18 is fitted into the concave portion 31, so that the circulating top 18 is rotated. Since it can be fitted and fixed to the end of the ball nut 16 while being restrained in the direction, the radial direction, and the circumferential direction, the circulating top 18 can be prevented from slipping out in the axial direction and the radial direction, and can be prevented from rotating in the circumferential direction. It can be made and reliable.

Further, since the tapping of the ball nut and the screwing work of the circulating top to the ball nut by a screw driver etc. which are conventionally required are not necessary,
Accordingly, the processing cost and the assembly cost are reduced, and the manufacturing cost can be reduced. Further, the circulating top 18 can be easily formed by two molds, and since there is no sharply pointed concave portion that causes stress concentration, the circulating top 18 can be made excellent in strength.

Further, since the concave portion 31 into which the strip-shaped fixing piece 30 is fitted is not limited in the depth direction, it is possible to make a thick fixing piece 30 and firmly fix the fixing piece 30 to the concave portion 31. Furthermore, since the concave portion 31 is located at a position apart from the transfer path of the rolling element 15 in the ball nut 16, it is possible to avoid the rolling element 15 from interfering with the concave portion 31,
It is possible to ensure smooth rolling of the rolling element 15.

The configuration of the ball circulating member, the fixing member, and the like in the ball screw device of the present invention is not limited to the above-mentioned embodiment, and can be appropriately changed without departing from the gist of the present invention. For example, in the above-described embodiment, the circulating top 18 is fixed to the end of the ball nut 16 only by fitting the fixing piece 30 provided on the circulating top 18 into the recess 31. And Figure 1
As shown in FIG. 0, a screw insertion hole 30a is formed in the fixing piece 30, and a tap hole 31a corresponding to the screw insertion hole 30a is formed in the recess 31 as shown in FIG.
May be fixed by screwing while being fitted in the recess 31.

Further, in the above embodiment, the circulating top 18
The case where one fixing piece 30 is provided in the above is taken as an example. However, as shown in FIG. 7, for example, as shown in FIG.
7 is provided with two strip-shaped fixing pieces (fixing members) 30 extending in opposite directions in the circumferential direction of the ball nut 16 on the end surface side (right side in FIG. 7B), and as shown in FIG. It is also possible to provide two recesses 31 corresponding to the two fixing pieces 30 on the end face of the above and to fit each fixing piece 30 into each recess 31.

Also in this case, as in FIG. 4 and FIG. 5 described above, as shown in FIG. 9, two fixing pieces 30 are provided with screw insertion holes 30a, respectively, and as shown in FIG.
You may make it form the tap hole 31a corresponding to each of the two screw insertion holes 30a in two recessed parts 31, and fix each fixing piece 30 in the recessed part 31 with a screw. Further, in the above-described embodiment, the case where the fixing member provided on the circulating top 18 is the band-shaped fixing piece 30 is taken as an example, but instead of this, as shown in FIG. 12, they are separated from each other by 180 ° in the circumferential direction. A ring-shaped fixing piece (fixing member) 40 extending in the circumferential direction of the ball nut 16 is provided on the end surface side of the ball nut 16 of the two circulating tops 18 arranged, and both circulating tops 18 are integrally connected by the fixing piece 40. Along with
As shown in FIG. 11, a recess 41 corresponding to the fixing piece 40 is provided on the end surface of the ball nut 16 so that the fixing piece 40 is recessed.
1, and further provided with a protrusion 50 at a position in contact with the radial inner surface of the ball nut 16 of the circulating top 18 and
By providing a recess 51 corresponding to the projection 50 on the inner surface of the ball nut 16 and fitting the projection 50 into the recess 51, the circulating top 18 is constrained in the axial direction, the radial direction and the circumferential direction. May be.

Also in this case, as shown in FIG. 14, a screw insertion hole 40a is formed in the ring-shaped fixing piece 40, and
As shown in FIG. 13, a tap hole 41a corresponding to the screw insertion hole 40a is formed in the recess 41 so that the fixing piece 40 is fixed to the recess 41.
It can be fixed by screwing in the state of fitting. Further, as shown in FIG. 15, an annular convex portion 42 is provided on the outer peripheral portion of the ring-shaped fixing piece 40, and an annular concave portion 42a corresponding to the annular convex portion 42 is provided on the peripheral surface on the bottom surface side of the concave portion 41 to form an annular shape. The fixing piece 40 with the convex portion 42 fitted in the annular concave portion
May be fitted in the recess 41.

In this case, when the annular convex portion 42 of the fixed piece 40 cannot be fitted into the annular concave portion of the concave portion 41 on the ball nut 16 side due to the shaft diameter, the fixed piece 40 may be cut in the radial direction. . Further, as shown in FIG. 18, a protrusion 50 is provided at a portion of the circulating top 18 in contact with the radially inner surface of the ball nut 16, and as shown in FIGS. 16 and 17, the radially inner surface of the ball nut 16 is provided. By providing a recess 51 corresponding to the protrusion 50 and fitting the protrusion 50 into the recess 51, the circulating top 18 may be constrained in the axial direction, the radial direction, and the circumferential direction.

In this way, the recess 31 of the fixed piece 30 is formed.
The effect of preventing the circulating top 18 from coming off in the axial direction by fitting it into the recessed portion and the effect of preventing the circulating top 18 from coming off in the axial direction by fitting the projection 50 into the recess 51 are more reliable in fixing the circulating top 18. Therefore, the reliability of the device can be further improved. It is needless to say that the reliability of the device can be enhanced by the axial, radial and circumferential retaining and rotation preventing effects of the protrusion 50 only by fitting the protrusions 50 into the recesses 51. .

Further, the projection 50 and the recess 51 may be provided at two or more places as shown in FIG. 19, and the projection 50 is provided in the ball nut 1 of the circulating top 18.
It can be provided at any place in contact with the radially inner surface of 6, for example, the place shown in FIG. Further, as shown in FIG. 21 and FIG. 22, an elastic protrusion 60 that elastically presses and contacts the inner surface of the circulating nut 18 in the radial direction of the ball nut 16 is provided in the circulating top 18.
The retaining effect of the shaft 8 in the axial direction may be further improved.

The elastic projection 60 is formed smaller than the above-mentioned projection 50, has no recess on the ball nut 16 side, and elastically presses and contacts the radially inner surface of the ball nut 16. When the circulating top 18 is fitted into the notch 19, a fixed force is applied to the circulating top 18 to use the elastic deformation of the material of the elastic protrusions 60 to fix the circulating top 18.
In this way, the effect of preventing the circulating top 18 from coming off in the axial direction is secured even in a high temperature environment to some extent, such as heat generation during high-speed operation.

Further, in the above embodiment, the strip-shaped fixing piece 3 is used.
0 and the case where the cross-sectional shape of the recess 31 is substantially rectangular is taken as an example, but instead of this, as shown in FIGS. 23 to 25, the strip-shaped fixing piece 30 is spread toward the bottom of the recess 31. By making the concave portion 31 have a reverse taper shape and a shape corresponding to the reverse taper shape of the strip-shaped fixing piece 30, it is possible to more reliably prevent the circulating top 18 from coming off in the axial direction. In this case, a slit 32 may be formed in the fixing piece 30 to facilitate fitting of the strip-shaped fixing piece 30 into the recess 31.

[0026]

As is apparent from the above description, according to the first aspect of the invention, the ball nut is constrained in the axial direction, the radial direction and the circumferential direction without using a screw, and the ball nut is restricted in the axial direction. Since the ball circulating member can be fitted and fixed to the end portion of the ball circulating member, the ball circulating member is prevented from coming off in the axial direction and the radial direction, and the rotation of the circumferential direction is prevented, so that the reliability of the device can be improved. To be

Further, since tapping of the ball nut and screwing work of the ball circulating member to the ball nut by a screw driver or the like, which are conventionally required, are unnecessary, the processing cost and the assembly cost are reduced accordingly. An effect that the cost can be reduced can be obtained. According to the invention of claim 2, in addition to the invention of claim 1,
It is possible to more securely fix the top-shaped ball circulating member.

According to the third aspect of the invention, similarly to the first aspect of the invention, the top of the ball nut is restrained in the axial direction, the radial direction and the circumferential direction without using the screw and the ball circulating member is attached to the end portion of the ball nut. Since they can be fitted and fixed, the ball circulation member can be prevented from coming off in the axial direction and the radial direction, and the rotation can be prevented in the circumferential direction, so that the reliability of the device can be improved. In addition, since tapping of the ball nut and screwing of the ball circulating member to the ball nut with a screwdriver, etc., which were required in the past, are no longer required, the processing cost and assembly cost are reduced accordingly, and the manufacturing cost is reduced. The effect that can be achieved is obtained.

According to the invention of claim 4, in addition to the invention of claim 3, the fixing of the ball circulating member can be made more reliable. According to the invention of claim 5, in addition to the invention of claim 3 or 4, the effect of preventing the ball circulating member from coming off in the axial direction can be further enhanced. In the invention of claim 6, in addition to the invention of any one of claims 3 to 5, the ball circulation member can be fixed more reliably.

[Brief description of drawings]

FIG. 1 is a partially cutaway schematic view for explaining a ball screw device that is an example of an embodiment of the present invention.

FIG. 2 is a left side view of FIG. 1 (a view seen from an end surface side of a ball nut).

FIG. 3 is a diagram showing a circulating top provided with a strip-shaped fixing piece, (b) is a front view, (a) is a left side view of (b),
(C) is a right side view of (b).

FIG. 4 is a view for explaining another embodiment of the present invention, and is a view seen from the end surface side of the ball nut.

FIG. 5 is a diagram showing a circulating top provided with a strip-shaped fixing piece, (b) is a front view, (a) is a left side view of (b),
(C) is a right side view of (b).

FIG. 6 is a view for explaining another embodiment of the present invention, and is a view seen from the end surface side of the ball nut.

FIG. 7 is a diagram showing a circulating top provided with a strip-shaped fixing piece, (b) is a front view, (a) is a left side view of (b),
(C) is a right side view of (b).

FIG. 8 is a view for explaining another embodiment of the present invention, and is a view seen from the end surface side of the ball nut.

9A and 9B are views showing a circulating top provided with a strip-shaped fixing piece, FIG. 9B is a front view, FIG. 9A is a left side view of FIG.
(C) is a right side view of (b).

FIG. 10 is a diagram showing a circulating top provided with a strip-shaped fixing piece, (b) is a front view, (a) is a left side view of (b),
(C) is a right side view of (b).

FIG. 11 is a view for explaining another embodiment of the present invention, and is a view seen from the end surface side of the ball nut.

FIG. 12 is a view of a circulating top provided with a ring-shaped fixing piece as viewed from the end face side in the axial direction.

FIG. 13 is a view for explaining another embodiment of the present invention, and is a view seen from the end face side of the ball nut.

FIG. 14 is a view of a circulating top provided with a ring-shaped fixing piece as seen from the end face side in the axial direction.

15 (a) and 15 (b) are views of a circulating top provided with a ring-shaped fixing piece, FIG. 15 (a) is a view seen from the end face side in the axial direction, and FIG. 15 (b) is the right side of FIG. A side view and (c) are schematic sectional views of a ball nut.

FIG. 16 is a view for explaining another embodiment of the present invention, and is a view seen from the end face side of the ball nut.

FIG. 17 is a right side view of FIG.

FIG. 18 is a view showing a circulating top provided with a strip-shaped fixing piece and a protrusion, (b) is a front view, (a) is a left side view of (b), and (c) is a right side surface of (b). It is a figure.

FIG. 19 is a view showing a circulating top provided with a strip-shaped fixing piece and a protrusion, (b) is a front view, (a) is a left side view of (b), and (c) is a right side surface of (b). It is a figure.

FIG. 20 is a view showing a circulating top provided with a strip-shaped fixing piece and a protrusion, (b) is a front view, (a) is a left side view of (b), and (c) is a right side surface of (b). It is a figure.

FIG. 21 is a view showing a circulating top provided with elastic protrusions,
(B) is a front view, (a) is a left side view of (b), (c) is a right side view of (b), and (d) is a rear view of (b).

FIG. 22 is a left half view as seen from the end surface side of the ball nut.

23A and 23B are views showing a circulating top in which a strip-shaped fixing piece is reversely tapered, where FIG. 23B is a front view, FIG. 23A is a left side view of FIG. 23B, and FIG. A front view, (d) is a rear view of (b).

FIG. 24 is a left half view as seen from the end face side of the ball nut.

25 is a cross-sectional view taken along line XX of FIG.

[Explanation of symbols]

10 ... Ball screw device 12 ... Screw groove (screw shaft side) 13 ... Screw shaft 14 ... Thread groove (nut side) 15 ... Ball 16 ... Ball nut 17 ... Ball return passage 18 ... Circulating top (ball circulating member) 19 ... Notch 20 ... scooping part 21 ... Ball circulation groove (ball circulation path) 30 ... Band-shaped fixing piece (fixing member) 30a ... Screw insertion hole 31, 41 ... Recess 31a ... Tap hole 32 ... Slit 40 ... Ring-shaped fixing piece (fixing member) 40a ... Screw insertion hole 41a ... Tap hole 42 ... Annular protrusion 50 ... Protrusion 51 ... Recess 60 ... Elastic protrusion

Claims (6)

[Claims] 1. A screw shaft having a spiral screw groove on the outer peripheral surface, a screw groove corresponding to the screw groove of the screw shaft on the inner peripheral surface, and a ball return passage penetrating in the axial direction. A ball nut loosely fitted to a screw shaft; and a ball-shaped ball circulating member having a ball circulation path that connects the screw grooves and the ball return path and fitted and fixed to both end surfaces of the ball nut. A ball screw device including: the both screw grooves; the ball return passage; and a plurality of balls rotatably interposed while rolling in the ball circulation passage, wherein the ball nut of the ball circulation member is in a radial direction. A ball screw device, characterized in that a projection is provided at a location that comes into contact with the inner surface, and a recess corresponding to the projection is provided on the inner surface in the radial direction of the ball nut. 2. The ball screw device according to claim 1, wherein an elastic protrusion that elastically presses and contacts the inner surface of the ball circulating member in the radial direction of the ball nut is provided at a position of the ball circulating member. 3. A screw shaft having a spiral screw groove on the outer peripheral surface, a screw groove corresponding to the screw groove of the screw shaft on the inner peripheral surface, and a ball return passage penetrating in the axial direction. A ball nut loosely fitted to a screw shaft; and a ball-shaped ball circulating member having a ball circulation path that connects the screw grooves and the ball return path and fitted and fixed to both end surfaces of the ball nut. A ball screw device provided with the both screw grooves, the ball return passage, and a large number of balls circulated so as to circulate while rolling in the ball circulation passage, wherein an end surface side of the ball nut of the ball circulation member. A ball screw device, characterized in that a band-shaped or ring-shaped fixing member extending in the circumferential direction of the ball nut is provided in the ball nut, and a recess corresponding to the fixing member is provided in the ball nut. 4. The ball circulating member is provided with a protrusion at a position in contact with a radially inner surface of the ball nut, and a recess corresponding to the protrusion is provided on a radially inner surface of the ball nut. Item 3. A ball screw device according to Item 3. 5. The strip-shaped fixing member has an inverse taper shape that widens toward the bottom of the recess, and the recess has a shape corresponding to the inverse taper shape. Ball screw device. 6. An elastic projection for elastically pressingly contacting the inner surface of the ball circulating member, which is in contact with the inner surface of the ball nut in the radial direction, is provided in the ball circulating member.
The ball screw device according to any one of 1.