JP2005083393A - Ball screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball screw capable of preventing a ball circulation piece from causing positional deviation in the axial direction of a nut and preventing it from coming off a circulation piece assembly hole. <P>SOLUTION: A substantially C-shaped locking ring 22 is provided between the ball circulation piece 17 assembled into the circulation piece assembly hole 21 and an end face 12a of the nut 12. The locking ring 22 is engaged with locking channels 23, 23 formed by opposing an inner face of the circulation piece assembly hole 21 mutually to position and fix the ball circulation piece 17 in the circulation piece assembly hole 21. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ball screw used in, for example, a machine tool as a device that converts rotational motion into linear motion.

  Conventionally, a ball screw used in a machine tool or the like includes a screw shaft having a screw shaft side ball screw groove on an outer peripheral surface, and a nut having a nut side ball screw groove on an inner peripheral surface formed on the outer periphery of the screw shaft. When the screw shaft (or nut) rotates about the axis, a large number of balls (rolling elements) built between the screw shaft side ball screw groove and the nut side ball screw groove are screw shaft side ball screws. A spiral ball rolling path formed between the groove and the nut-side ball screw groove rolls, and along with this, the nut (or screw shaft) moves linearly in the axial direction.

In order to continue the linear motion of the ball screw nut or the screw shaft, it is necessary to infinitely circulate the ball rolling on the spiral ball rolling path. For example, the compact type disclosed in Patent Document 1 In a ball screw, a ball having a ball return guide path that forms a linear ball return path in one end of the nut from one end to the other end of the nut and guides the ball that has rolled the spiral ball rolling path in the ball return path. The circulation piece is incorporated into circulation piece insertion holes formed on both end faces of the nut so that the ball is circulated infinitely.
Utility Model Registration No. 3034052 Specification

However, the above-described ball screw is often assembled by fixing a ball circulation piece incorporated in a circulation piece assembly hole to a nut with a screw. For this reason, the screws are loosened due to aging or vibration of the parts, and there is a possibility that the ball circulation piece may be displaced in the axial direction of the nut due to the loosening of the screws and come out of the circulation piece assembly hole.
Therefore, the present invention has been made paying attention to such a problem, and provides a ball screw capable of improving the reliability by preventing the ball circulation piece from coming out of the circulation piece insertion hole. With the goal.

  In order to achieve the above object, the invention of claim 1 is a screw shaft having a screw shaft side ball screw groove on the outer peripheral surface, and a nut side ball screw groove facing the screw shaft side ball screw groove of the screw shaft. And a spiral ball rolling path formed between the screw shaft side ball screw groove and the nut side ball screw groove in accordance with the rotation of the screw shaft or the nut. A ball circulation piece having a ball return guide path for guiding a ball rolled on the spiral ball rolling path to a ball return path formed in the nut from one end to the other end of the nut; A ball screw constructed by incorporating the ball circulation piece into the circulation piece insertion holes formed on both end faces of the nut, and the ball circulation piece incorporated in the circulation piece insertion hole and the ball screw A substantially C-shaped retaining ring is provided between the end face of the nut and the retaining ring is fitted in a retaining groove formed opposite to the inner surface of the circulation piece assembly hole. And

According to such a configuration, unlike the case where the ball circulation piece is fixed to the nut with a screw, the ball circulation piece is not displaced in the axial direction of the nut due to the loosening of the screw. It is possible to prevent the escape from the circulation frame assembly hole.
According to a second aspect of the present invention, in the ball screw according to the first aspect, the ball circulation piece is provided with an engagement piece that engages the retaining ring with the outer diameter side of the nut. Yes, by adopting such a configuration, the engagement piece portion can prevent the ball circulation piece from being displaced on the inner diameter side of the nut.

According to a third aspect of the present invention, in the ball screw according to the first aspect, the ball circulation piece is provided with an engagement recess that engages the retaining ring with the outer diameter and inner diameter of the nut. By adopting such a configuration, the engagement recess can prevent the ball circulation piece from being displaced on the inner diameter side of the nut.
According to a fourth aspect of the present invention, in the ball screw according to the first aspect, the ball circulation piece is provided with a slit that engages the retaining ring with the outer diameter and inner diameter side of the nut. By adopting such a configuration, it is possible to prevent the ball circulation piece from being displaced on the inner diameter side of the nut by the slit.

According to the first aspect of the present invention, since the ball circulation piece does not shift in the axial direction of the nut due to the loosening of the screw as in the case where the ball circulation piece is fixed with a screw, It is possible to prevent the ball from coming out of the circulation frame assembly hole and to improve the reliability of the ball screw.
According to the second to fourth aspects of the present invention, in addition to the effects described above, the ball circulation piece can be prevented from being displaced on the inner diameter side of the nut.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 6 are views showing a first embodiment of the present invention, and FIG. 1 is a partial sectional side view of a ball screw according to the first embodiment of the present invention. As shown in the figure, the ball screw 10 according to the first embodiment of the present invention includes a screw shaft 11 and a nut 12 having an inner peripheral surface on the outer periphery of the screw shaft 11. A screw shaft side ball screw groove 13 is formed on the outer peripheral surface of the screw shaft. The ball screw groove 13 is opposed to a nut-side ball screw groove 14 formed on the inner peripheral surface of the nut 12, and a large number of balls 15 are incorporated between these ball screw grooves 13, 14. Further, a spiral ball rolling path 16 is formed between the ball screw grooves 13, 14, and when the screw shaft 11 (or nut 12) rotates around the axis, the ball 15 is spiral ball rolling path 16. As a result, the nut 12 (or the screw shaft 11) linearly moves in the axial direction.

  Further, the ball screw 10 has a ball circulation piece 17 having a structure as shown in FIG. The ball circulation piece 17 includes a tongue portion 18 for scooping up the ball 15 from the screw shaft side ball screw groove 13 and a linear ball return passage 20 formed in the nut 12 from one end to the other end of the nut 12 (see FIG. 1) and a ball return guide path 19 for guiding the ball 15 so that the ball 15 picked up by the tongue 18 is introduced into the ball return path 20 through the ball return guide path 19. It has become.

FIG. 3 is a view showing an end face of the nut 12, and as shown in FIG. 3, circulation piece insertion holes 21 for incorporating the ball circulation piece 17 into the nut 12 are formed on both end faces of the nut 12. .
4 is a cross-sectional view taken along line IV-IV in FIG. 3. As shown in FIG. 4, there is a gap between the ball circulation piece 17 incorporated in the circulation piece insertion hole 21 and the end face 12a of the nut 12. A retaining ring 22 as shown in FIG. The retaining ring 22 is formed, for example, by bending a metal wire into a substantially C shape, and is fitted in retaining grooves 23 and 23 formed opposite to the inner surface of the circulation piece assembly hole 21. Yes. The retaining ring 22 is incorporated in the retaining groove 23 from the inner diameter side of the nut 12.

FIG. 2 is a perspective view of the ball circulation piece 17, and as shown in the figure, an end piece of the ball circulation piece 17 is provided with an engagement piece portion 24 that engages with the retaining ring 22 on the outer diameter side of the nut 12. It has been.
As described above, a substantially C-shaped retaining ring 22 is provided between the ball circulating piece 17 incorporated in the circulating piece assembly hole 21 and the end surface 12a of the nut 12, and this retaining ring 22 is provided in the circulation piece assembly hole. When the ball circulation piece 17 is fitted into the retaining grooves 23 and 23 formed opposite to the inner surface of the ball 23, the ball circulation piece 17 is positioned and fixed in the circulation piece insertion hole 21. Thus, unlike the case where the ball circulation piece 17 is fixed with a screw, the ball circulation piece 17 is not displaced in the axial direction of the nut 12 due to the loosening of the screw. It is possible to prevent the ball screw from coming out of the insertion hole 21 and to improve the reliability of the ball screw.

  Further, as in the first embodiment described above, by providing the ball circulation piece 17 with the engagement piece portion 24 that engages with the retaining ring 22 on the outer diameter side of the nut 12, the ball circulation piece 17 can be connected to the nut 12. The engagement piece portion 24 can prevent the displacement from occurring on the inner diameter side. Furthermore, in the first embodiment described above, the crescent-shaped engagement piece portion 24 that engages with the assembly-side tip portion 22a (see FIG. 4) of the retaining ring 22 protrudes from the end surface of the ball circulation piece 17. Thus, since the ball circulation piece 17 is pressed in the direction of the arrow in FIG. 3 (the outer diameter direction of the nut 12) by the elastic force of the retaining ring 22, the positional deviation of the ball circulation piece 17 can be prevented.

  The present invention is not limited to the embodiment described above. For example, in the first embodiment, in order to prevent the ball circulation piece 17 from being displaced on the inner diameter side of the nut 12, the engagement piece portion 24 that engages with the retaining ring 22 on the outer diameter side of the nut 12 is formed as a ball. Although provided in the circulation piece 17, as in the second embodiment shown in FIGS. 7 and 8, the engagement recess 25 that engages the retaining ring 22 on the outer diameter and inner diameter side of the nut 12 is provided with the ball circulation piece 17. The same effect can be obtained even if it is provided. Further, as in the third embodiment shown in FIGS. 9 and 10, even if the ball circulation piece 17 is provided with a slit 26 that engages the retaining ring 22 on the outer diameter and inner diameter sides of the nut 12, the first and first The same effect as that of the second embodiment can be obtained.

  Further, as in the fourth embodiment shown in FIG. 11 and the fifth embodiment shown in FIG. 12, the retaining ring 22 is engaged with the front outer peripheral edge 22 b of the retaining ring 22 and the retaining ring 22 of the ball circulation piece 17 is engaged. An annular tapered surface 27 that is pressed to the end surface side may be provided on the nut 12. With such a configuration, the retaining ring 22 is pressed against the end surface side of the ball circulation piece 17 by the tapered surface 27 provided on the nut 12, so that the positional deviation of the ball circulation piece 17 in the axial direction of the nut 12 is prevented. Can be prevented.

It is a partial cross section side view of the ball screw concerning a 1st embodiment of the present invention. It is a perspective view of the ball circulation piece shown in FIG. It is a figure which shows the principal part of the ball screw which concerns on the 1st Embodiment of this invention. It is sectional drawing which follows the IV-IV line of FIG. It is a front view of the retaining ring shown in FIG. It is a front view of the ball circulation piece shown in FIG. It is a figure which shows the principal part of the ball screw which concerns on the 2nd Embodiment of this invention. It is a front view of the ball circulation piece shown in FIG. It is a figure which shows the principal part of the ball screw which concerns on the 3rd Embodiment of this invention. It is sectional drawing which follows the XX line of FIG. It is sectional drawing which shows the principal part of the ball screw which concerns on the 4th Embodiment of this invention. It is sectional drawing which shows the principal part of the ball screw which concerns on the 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Screw shaft 12 Nut 13 Screw shaft side ball screw groove 14 Nut side ball screw groove 15 Ball 16 Spiral ball rolling path 17 Ball circulation piece 18 Tongue part 19 Return guide path 20 Ball return path 21 Circulation piece insertion hole 22 Retaining prevention Ring 23 Retaining groove 24 Engaging piece 25 Engaging recess 26 Slit 27 Tapered surface

Claims (4)

A screw shaft having a screw shaft side ball screw groove on the outer peripheral surface, a nut having a nut side ball screw groove facing the screw shaft side ball screw groove of the screw shaft on the inner peripheral surface, and the screw shaft side ball screw groove And a plurality of balls that roll in accordance with the rotation of the screw shaft or the nut, and the spiral ball rolling path. A circulation piece insertion hole formed on both end surfaces of the nut, and a ball circulation piece having a ball return guide path for guiding the ball in the nut to a ball return passage formed from one end to the other end of the nut. In the ball screw configured to incorporate the ball circulation piece in
A substantially C-shaped retaining ring is provided between the ball circulation piece incorporated in the circulation piece insertion hole and the end surface of the nut, and this prevention ring is formed opposite to the inner surface of the circulation piece insertion hole. A ball screw characterized by being fitted in the retaining groove formed.   The ball screw according to claim 1, wherein an engagement piece that engages the retaining ring on the outer diameter side of the nut is provided on the ball circulation piece.   2. The ball screw according to claim 1, wherein an engagement recess that engages the retaining ring on the outer diameter and inner diameter side of the nut is provided in the ball circulation piece.   2. The ball screw according to claim 1, wherein a slit that engages the retaining ring on the outer diameter and inner diameter side of the nut is provided in the ball circulation piece.

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