JP2002327825A - Ball screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively and easily cope with changes in various sizes such as diametral size, axial size and board thickness of a holder 13 in regard to a finite stroke type ball screw converting a rotational motion of a screw shaft 11 into a linear motion of a nut member 12 by screwing the screw shaft 11 to the nut member 12 via balls 14. SOLUTION: The ball screw comprises the holder 13 helically formed along a thread groove 15, having a plurality ball housing holes in a longitudinal direction and interposed in a gap between the screw shaft 11 and the nut member 12, and the balls 14 housed in the ball housing holes and fit in thread grooves 15 and 18 of the screw shaft 11 and the nut member 12 so as to roll. The various sizes such as the diametral size, the axial size, and the board thickness of the holder 13 can be easily changed by changing the number, winding diameter, pitch or the like of helical windings. Since the holder 13 can be manufactured just by helically winding a thin plate, labor of remaking a mold in a size change becomes unnecessary and it can be manufactured inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a machine tool or a steering device of an automobile, etc., in which a screw shaft and a nut member are screwed together via a ball. Regarding the ball screw that converts to motion,
In particular, the present invention relates to a finite stroke ball screw that performs relative motion between a screw shaft and a nut member without infinitely circulating a ball.

[0002]

2. Description of the Related Art A conventional ball screw will be described with reference to FIGS.

FIG. 3 is a sectional view of the ball screw 30, and FIG. 4 is a perspective view of a retainer 33 of the ball screw 30.

[0004] The ball screw 30 is configured by screwing a screw shaft 31 and a nut member 32 through a plurality of balls 34 and interposing a retainer 33 between the screw shaft 31 and the nut member 32. ing.

On the outer peripheral surface of the screw shaft 31, a screw groove 35 and a screw thread 36 which are alternately arranged in a spiral shape are formed.

The nut member 32 has a through hole 37 having a diameter larger than the diameter of the screw shaft 31, and a screw groove 38 corresponding to the screw groove 35 of the screw shaft 31 is formed on the inner peripheral surface 37. .

[0007] As shown in FIG.
It is formed in a cylindrical shape having a size that fits on the screw shaft 31, and a plurality of long holes 39 extending in the axial direction are formed in the body in the circumferential direction.

The ball screw 30 has a retainer 33 interposed in a gap between the screw shaft 31 and the nut member 32, accommodates the ball 34 in an elongated hole 39 of the retainer 33, and has a thread groove of the screw shaft 31. The ball 34 is rotatably fitted into the thread groove 35 of the nut member 32 and the nut 35.

According to the ball screw 30 configured as described above, the nut member 32 moves in the axial direction via the ball 34 with the rotation of the screw shaft 31 in a use state in which the nut member 32 does not rotate. That is, the screw shaft 3
One rotational movement is changed to a linear movement of the nut member 32.

[0010]

SUMMARY OF THE INVENTION A conventional ball screw 30
The retainer 33 is formed by forming a ring shape by deep drawing a thin plate using a mold, and then opening a long hole 39. The dimensions of the retainer 33 are the ball P. C. D (Pitch Ci
rcle Diameter), lead of screw, number of balls, etc.

For this reason, the dimensions of the mold at the time of deep drawing are determined by the diameter D, the axial dimension L, the plate thickness, etc. of the retainer 33.
If these values are changed, a new die corresponding to the holder 33 must be manufactured, and there is a problem that the manufacturing cost increases.

When the axial dimension of the retainer 33 becomes long and deep drawing is difficult, there are a method of rounding and welding thin plates and a method of connecting them in a clinch shape. However, there is a problem that the diameter dimension D and the plate thickness are limited, and the applicable range is limited.

SUMMARY OF THE INVENTION An object of the present invention is to provide a ball screw capable of easily and inexpensively coping with changes in various dimensions such as a diameter dimension, an axial dimension, and a plate thickness of a cage.

[0014]

The ball screw according to the present invention comprises:
A screw shaft having a thread groove on the outer peripheral surface, a nut member externally fitted to the screw shaft via a gap, and having a thread groove corresponding to the thread groove of the screw shaft on the inner peripheral surface; A retainer formed in a spiral shape and having a plurality of ball receiving holes in the longitudinal direction and interposed in a gap between the screw shaft and the nut member; and a screw groove of the screw shaft received in the ball receiving hole. And a plurality of balls that are rollably fitted into the thread grooves of the nut member.

According to the ball screw of the present invention, since the retainer is formed in a spiral shape along the thread groove, the retainer can be easily formed by changing the number of spiral windings, the winding diameter, the pitch, and the like. It is possible to change various dimensions such as diameter, axial dimension, plate thickness, etc., and it can be manufactured by simply winding a thin plate in a spiral shape. Can be manufactured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view of the ball screw 10, and FIG. 2 is a perspective view of a retainer 13 of the ball screw 10.

The ball screw 10 is configured by screwing a screw shaft 11 and a nut member 12 through a plurality of balls 14 and interposing a retainer 13 between the screw shaft 11 and the nut member 12. ing.

On the outer peripheral surface of the screw shaft 11, screw grooves 15 and screw threads 16 which are alternately arranged in a spiral shape are formed.

The nut member 12 has a through hole 17 having a diameter larger than the diameter of the screw shaft 11, and a screw groove 18 corresponding to the screw groove 15 of the screw shaft 11 is formed on the inner peripheral surface 17. .

Further, as shown in FIG.
It is formed in a helical shape having a size that fits on the screw shaft 11. That is, the strip-shaped thin plate is screwed into the screw groove 1 of the screw shaft 11.
5, and a plurality of ball receiving holes 19 are formed in the longitudinal direction.

The ball screw 10 has a retainer 13 interposed in a gap between the screw shaft 11 and the nut member 12, accommodates the ball 14 in a ball accommodation hole 19 of the retainer 13, and The ball 14 is rotatably fitted in the groove 15 and the thread groove 18 of the nut member 12.

Next, the operation of the ball screw 10 will be described.

In a use state in which the nut member 12 does not rotate, the nut member 12 moves in the axial direction via the ball 14 as the screw shaft 11 rotates. That is, the rotational movement of the screw shaft 11 is changed to the linear movement of the nut member 12.

According to the ball screw 10 configured as described above, since the retainer 13 is formed in a spiral shape along the screw grooves 15 and 18, the number of spiral windings, the winding diameter, the pitch and the like are determined. By changing, it is easy to
Various dimensions such as diameter, axial dimension, plate thickness, etc. can be changed,
In addition, the dimensional application range is widened.

Further, since the retainer 13 can be manufactured simply by spirally winding a thin plate, there is no need to rework a mold when changing the dimensions, and it can be manufactured at low cost.

[0027]

According to the ball screw of the present invention, when the dimensions of the cage, such as the radial dimension, axial dimension, and plate thickness, are changed,
The effect is obtained that it can be dealt with cheaply and easily.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a ball screw according to an embodiment of the present invention.

FIG. 2 is a perspective view of a ball screw retainer according to the embodiment of the present invention.

FIG. 3 is a sectional view of a conventional ball screw.

FIG. 4 is a perspective view of a conventional ball screw retainer.

[Explanation of symbols]

 Reference Signs List 10 Ball screw 11 Screw shaft 12 Nut member 13 Cage 14 Ball 15, 18 Screw groove 19 Ball receiving hole

Claims (1)

[Claims] A screw member having a thread groove on an outer peripheral surface thereof; a nut member externally fitted to the screw shaft via a gap; and having a thread groove on an inner peripheral surface corresponding to the thread groove of the screw shaft; A retainer spirally formed along the screw groove and having a plurality of ball receiving holes in a longitudinal direction and interposed in a gap between the screw shaft and the nut member; A ball screw comprising: a shaft thread groove; and a plurality of balls rollingly fitted into the nut member thread groove.