JP2007085423A - Linear motion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear motion device capable of securing smooth rolling movement of a rolling body in a rolling body return passage. <P>SOLUTION: A plurality of gutters 18 are formed in an inner surface of the rolling body return passage 17 formed in a rolling body circulation member 16 along the longitudinal direction of the rolling body return passage 17 and contact area of the rolling body 15 with the inner surface of the rolling body return passage 17 is reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a linear motion device such as a ball screw or a linear motion guide device.

  A ball screw for converting a rotational motion into a linear motion has a screw shaft having a spiral ball rolling groove on the outer peripheral surface and a spiral ball rolling groove facing the ball rolling groove of the screw shaft on the inner peripheral surface. And a number of balls that roll in accordance with the rotational movement of the screw shaft or nut through a ball rolling path formed between the ball rolling groove of the nut and the ball rolling groove of the screw shaft. It has a configuration with. And what is called a tube circulation type ball screw has a configuration in which a U-shaped ball circulation tube is assembled to a nut, and a ball is introduced into a ball return passage formed in the ball circulation tube to perform circulation motion. (See Patent Document 1).

Further, a linear guide device used for a feed mechanism of a machine tool or the like is a linear rolling element rolling device facing a guide rail and linear rolling element rolling grooves formed on left and right side portions of the guide rail. A slider having a moving groove, and a rolling element rolling path formed between the rolling element rolling groove of the slider and the rolling element rolling groove of the guide rail rolls along with the relative linear motion of the slider. The rolling elements rolling on the rolling element rolling path are introduced into a rolling element return passage formed in the slider so as to circulate (see Patent Document 2). .
JP 2003-97664 A JP 2000-46052 A

In such a linear motion device such as a ball screw or a linear motion guide device, in order to smoothly roll the rolling element in the rolling element return passage, the entry angle of the rolling element entering the rolling element return passage and the rolling element return The circulation radius of the rolling elements in the passage has been devised. However, the rolling element circulates while in contact with the rolling element circulation member such as a ball circulation tube, and a frictional force is generated at the contact portion between the rolling element and the rolling element circulation member. It was a factor that hindered efficiency. Further, since the rolling element is not loaded in the rolling element return passage, it is difficult to roll, and it is easy to circulate while sliding, so the frictional force cannot be ignored.
The present invention has been made paying attention to the above-described problems, and an object of the present invention is to provide a linear motion device capable of ensuring a smooth rolling motion of the rolling element in the rolling element return passage.

  In order to achieve the above object, the invention of claim 1 is formed by a guide shaft, a movable body movably provided in the axial direction of the guide shaft, and opposed to the guide shaft and the movable body. A plurality of rolling elements that roll with the rotational motion of the guide shaft or the linear motion of the movable body between the spiral or linear rolling body rolling grooves formed, and circulate through the rolling body In the linear motion device in which the rolling element return passage is formed in the movable body or in the rolling member circulation member mounted on the movable body, a plurality of grooves are formed on the inner surface of the rolling body return passage in the longitudinal direction of the ball return passage. It was provided along.

  According to a second aspect of the present invention, there is provided a guide shaft, a movable body provided so as to be movable in the axial direction of the guide shaft, and a spiral or linear shape formed opposite to each other on the guide shaft and the movable body. A plurality of rolling elements that roll with rolling motion of the guide shaft or linear motion of the movable body between the rolling body rolling grooves, and the movable body return passage for circulating the rolling body is movable. In a linear motion device formed in a body or a rolling element circulation member mounted on the movable body, a large number of dimples are provided on the inner surface of the rolling element return passage.

  In the linear motion device according to the first and second aspects of the present invention, the contact area of the rolling element with respect to the inner surface of the rolling element return passage is reduced as compared with the conventional linear motion device described above. Therefore, frictional force that hinders the smooth rolling motion of the rolling element is less likely to be generated at the contact portion between the rolling element and the rolling element return passage, so that the rolling element can be smoothly rolled in the rolling member return passage. can do.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a schematic configuration of a linear motion device according to the first embodiment of the present invention. A linear motion device 10 shown in FIG. 1 includes a screw shaft 11 as a guide shaft and a nut 12 as a movable body. On the outer peripheral surface of the screw shaft 11, a spiral rolling member rolling groove 13 is formed on the screw shaft. 11 is formed from one end to the other end. This rolling element rolling groove 13 is opposed to a spiral rolling element rolling groove 14 formed on the inner peripheral surface of the nut 12, and between the rolling element rolling groove 13 and the rolling element rolling groove 14. Are arranged with a large number of rolling elements 15 formed in a spherical shape.

  The rolling element 15 rolls on the rolling element rolling grooves 13 and 14 with the relative rotational movement of the screw shaft 11 or the nut 12, and rolls on the rolling element rolling grooves 13 and 14. The rolling element 15 is introduced into a tubular rolling element circulation member 16 assembled to the nut 12 and circulates through the rolling element return passage 17 formed in the rolling element circulation member 16. Yes. The rolling element return passage 17 is formed in the rolling element circulation member 16 with a hole diameter slightly larger than the diameter of the rolling element 15 (for example, 6.90 mm when the diameter of the rolling element 15 is 6.35 mm).

  2 is a partial cross-sectional side view of the rolling element circulation member shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 2. As shown in FIGS. A plurality of grooves 18 are formed along the longitudinal direction of the rolling element return passage 17. These grooves 18 are formed on the inner surface of the rolling element return passage 17 with a width of approximately 1/5 Da to 1/20 Da, where the diameter of the rolling element 15 is Da. When the width of the groove 18 is w, the groove 18 is formed on the inner surface of the rolling element return passage 17 at an interval of approximately 2w to 4w.

  In the linear motion device configured as described above, the contact area of the rolling element 15 with respect to the inner surface of the rolling element return passage 17 is reduced as compared with the rolling element return passage 17 having no groove 18 on the inner surface. Therefore, a frictional force that hinders the smooth rolling motion of the rolling element 15 is less likely to be generated at the contact portion between the rolling element 15 and the rolling element return passage 17, so that the rolling element 15 smoothly moves in the rolling element return passage 17. Can ensure a smooth rolling exercise. Further, by providing a plurality of grooves 18 on the inner surface of the rolling element return passage 17, the lubricant is held in the grooves 18, and the lubricating effect in the rolling element return passage 17 is prolonged by the lubricant accumulated in the grooves 18. Can last over.

FIG. 4 is a view showing a second embodiment of the present invention. The second embodiment is different from the first embodiment in that a large number of dimples 19 are provided on the inner surface of the rolling element return passage 17. It is. The size of the dimple 19 is approximately 1/5 to 1/20 with respect to the diameter Da of the rolling element.
According to such a configuration, as in the first embodiment described above, the contact area of the rolling element 15 with respect to the inner surface of the rolling element return passage 17 is reduced, and friction that inhibits the smooth rolling motion of the rolling element 15 is prevented. Since a force is less likely to be generated at the contact portion between the rolling element 15 and the rolling element return passage 17, a smooth rolling motion of the rolling element 15 can be ensured in the rolling element return passage 17. Furthermore, by providing a large number of dimples 19 on the inner surface of the rolling element return passage 17, the lubricant is held by the dimples 19, and the lubricating effect in the rolling element return passage 17 is maintained for a long time by the lubricant accumulated in the dimples 19. Can last.

  Although the case where this invention was applied to the ball screw was illustrated in embodiment shown in FIGS. 1-4, this invention is not limited to this, For example, it can apply also to a linear motion guide apparatus. In the above-described embodiment, the rolling element is illustrated as being formed in a spherical shape. However, the present invention is not limited to this, and the present invention is also applicable to a linear motion device in which the rolling element is formed in a cylindrical shape. Can do.

It is a figure which shows schematic structure of the linear_motion | direct_drive apparatus which is the 1st Embodiment of this invention. It is a side view of the rolling element circulation tube shown in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is a figure which shows the 2nd Embodiment of this invention.

Explanation of symbols

10 linear motion device 11 screw shaft (guide shaft)
12 Nut (movable body)
13, 14 Rolling body rolling groove 15 Rolling body 16 Rolling body circulating member 17 Rolling body return passage 18 Groove 19 Dimple

Claims (2)

Between a guide shaft, a movable body provided to be movable in the axial direction of the guide shaft, and a spiral or linear rolling element rolling groove formed opposite to the guide shaft and the movable body. A plurality of rolling elements that roll in accordance with the rotational motion of the guide shaft or the linear motion of the movable body, and a rolling body return passage for circulating the rolling body is attached to the movable body or the movable body. In the linear motion device formed in the rolling element circulating member,
A linear motion device characterized in that a plurality of grooves are provided on the inner surface of the rolling element return passage along the longitudinal direction of the ball return passage. Between a guide shaft, a movable body provided so as to be movable in the axial direction of the guide shaft, and a spiral or linear rolling element rolling groove formed opposite to each other on the guide shaft and the movable body A plurality of rolling elements that roll in accordance with the rotational movement of the guide shaft or the linear movement of the movable body, and a rolling body return passage for circulating the rolling body is attached to the movable body or the movable body In the linear motion device formed in the formed rolling element circulation member,
A linear motion device comprising a plurality of dimples provided on an inner surface of the rolling element return passage.

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