JPH066795U - Ball screw sealing device - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the sealing property. The dividing surface 5b1 is inclined by an angle θ1 in the twist direction of the spiral groove of the screw shaft 1, and is further inclined by an angle θ2 inward of the ball nut (direction A). When the screw shaft 1 rotates in a predetermined direction, the foreign matter attached to the surface of the spiral groove 1a is scraped off by the dividing surface 5b1. The foreign matter P scraped off is discharged to the outside (B direction) outer diameter side of the ball nut along the dividing surface 5b1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a ball screw sealing device.

[0002]

[Prior art]

 In a ball screw, multiple balls are arranged between the spiral groove provided on the outer peripheral surface of the screw shaft and the spiral groove provided on the inner peripheral surface of the ball nut, and the rotational power of the screw shaft is transmitted through the balls to the ball nut. However, in order to prevent the lubricant filled inside the ball nut from leaking out and the foreign matter from entering from the outside, as shown in FIG. 7, it is fitted into the spiral groove 21a of the screw shaft 21. The ring-shaped labyrinth seal member 25 having the protrusions 25 a that fit together is attached to both ends of the ball nut 22. The seal member 25 is fixed by a set screw 29 or the like screwed into the screw hole 22b of the ball nut 22.

[0003]

[Problems to be solved by the device]

 In the above sealing device, the sealing member 25 is fitted to the screw shaft 21 and then fixed by the setscrew 29 screwed to the ball nut 22. The fitting clearance between the protrusion 25a and the spiral groove 21a is It depends on the dimensional relationship between the seal member 25 and the screw shaft 21. Therefore, a large clearance is generated between the protrusion 25a and the spiral groove 21a, and the sealability may be insufficient depending on the usage conditions.

An object of the present invention is to improve the sealing property of a sealing device in a ball screw.

[0005]

[Means for Solving the Problems]

 The sealing device according to claim 1 is one in which the sealing member itself is divided into a plurality of parts, and the sealing device according to claim 2 is one in which a part of the sealing member is divided into a plurality of parts.

Then, by elastically pressing the divided portion in the inner diameter direction, the fitting clearance between the protrusion of the seal member and the spiral groove of the screw shaft is made zero or less.

The fitting clearance of zero or less means a state where the fitting clearance is zero or a state with a tight margin (minus clearance).

Each divided surface of the seal member is inclined with respect to the axis in the twisting direction of the spiral groove of the screw shaft, and is further inclined inward of the ball nut.

[0009]

[Action]

 Since the protrusion of the seal member comes into close contact with the spiral groove of the screw shaft, the leakage of lubricant and the intrusion of foreign matter are unlikely to occur.

When the screw shaft rotates, foreign matter adhering to the surface of the spiral groove is scraped off by the one dividing surface of the seal member. The foreign matter scraped off is discharged to the outside outer diameter side of the ball nut along the dividing surface. The lubricant is pushed toward the inner diameter side of the ball nut by the other dividing surface.

[0011]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a plurality of balls 3 are arranged between a spiral groove 1 a provided on the outer peripheral surface of the screw shaft 1 and a spiral groove 2 a provided on the inner peripheral surface of the ball nut 2. . When the screw shaft 1 rotates, the rotational power thereof is transmitted to the ball nut 2 via the ball 3, and the ball nut 2 moves in the X-axis direction. For example, when the screw shaft 1 rotates in the Ra direction shown in the same figure, the ball nut 2 moves in the A direction shown in the same figure, and when the screw shaft 1 rotates in the Rb direction, it moves in the B direction. A seal member 5 is attached to the end of the ball nut 2.

As shown in FIG. 2, the seal member 5 is formed by molding a resin material or a rubber material such as fluororubber into a ring shape, and then dividing the ring material into four parts at equal circumferential positions. is there. Each of the divided surfaces 5b1 and 5b2 is inclined with respect to the axis X by an angle θ1 in the twist direction (θ direction) of the spiral groove 1a. Further, the seal member 5 has a protrusion 5a protruding toward the inner diameter side. The protrusion 5a has a shape and size corresponding to the spiral groove 1a.

Each of the four divided portions of the seal member 5 is elastically pressed toward the inner diameter side by the ball plunger 8 screwed into the screw hole 2 b of the ball nut 2. Therefore, as shown in an enlarged view in FIG. 1b, the fitting clearance between the protrusion 5a and the spiral groove 1a is zero or slightly minus (with a tightening margin). In this way, since the protrusion 5a is in close contact with the spiral groove 1a, the lubricant in the ball nut 2 does not easily leak to the outside, and foreign matter does not easily enter from the outside.

When the screw shaft 1 rotates in the Rb direction, foreign matter attached to the surface of the spiral groove 1a is scraped off by the dividing surface 5b1. As shown in FIG. 3 (FIG. 3a is a view of the dividing surface 5b1 viewed from the Y1 direction in FIG. 2b), the dividing surface 5b1 is inclined by an angle θ1 in the twist direction of the spiral groove 1a, and The foreign matter P, which is inclined by an angle θ2 toward the inner side of the nut 2 (direction A), is discharged to the outside (direction B) of the ball nut 2 along the dividing surface 5b1. .

As shown in FIG. 4 (FIG. 4a is a view of the dividing surface 5b2 viewed from the Y2 direction in FIG. 2a), the dividing surface 5b2 also has a twisting direction of the spiral groove 1a, like the dividing surface 5b1. To the inner side (direction A) of the ball nut 2 by an angle θ2. Therefore, when the screw shaft 1 rotates in the Ra direction, the lubricant in the ball nut 2 is pushed to the inside (A direction) inner diameter side of the ball nut 2 by the dividing surface 5b2.

In the embodiment shown in FIGS. 5 and 6, the seal member 5 is divided into a plurality of parts from the end surface 5 c facing the outer side of the ball nut 2 to the middle part, and the divided part is divided into a plurality of garter springs 10. It is designed so that it is elastically pressed toward the inner diameter side. The same operation and effect as those of the above-described seal device are achieved.

The above description also applies to the seal member 5 mounted on the side (end in the direction A) of the ball nut 2 not shown. That is, also with respect to the seal member 5, the dividing surfaces 5b1 and 5b2 are inclined in the twist direction of the spiral groove 1a by an angle θ1, and further inward of the ball nut 2 by an angle θ2. However, regarding this seal member 5, the direction A is the outer side of the ball nut 2, and the direction B is the inner side of the ball nut 2. Therefore, the direction of the angle θ2 is opposite to the direction of the seal member 5 attached to the B-direction side end. Further, the configuration shown in FIG. 1 and the configuration shown in FIG. 5 may be used together.

[0019]

[Effect of device]

 According to the present invention, the protrusion of the seal member is closely attached to the spiral groove of the screw shaft with a fitting clearance of zero or less, and moreover, the foreign matter scraped from the surface of the spiral groove is external to the ball nut along the dividing surface. Since the lubricant is discharged to the outer diameter side and the lubricant is pushed to the inner inner diameter side of the ball nut by the dividing surface, the sealability is remarkably improved as compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a sectional view (FIG. A) showing an embodiment of the present invention and a partially enlarged sectional view (FIG. B) in FIG.

FIG. 2 is a front view (FIG. A) and a side view (FIG. B) showing a seal member in FIG.

FIG. 3 is a perspective view (FIG. A is a view seen from the Y1 direction of FIG. 2b) showing a divided surface of the seal member, an upper plan view of FIG. A (FIG. B), and a front view of FIG. c).

FIG. 4 is a perspective view (FIG. A is a view seen from the Y2 direction of FIG. 2b) showing a divided surface of the seal member, an upper plan view of FIG. A (FIG. B), and a front view of FIG. c).

FIG. 5 is a cross-sectional view showing another embodiment of the present invention.

6 is a front view (FIG. A) and a side view (FIG. B) showing the seal member in FIG.

FIG. 7 is a cross-sectional view showing a conventional sealing device.

[Explanation of symbols]

 1 Screw Shaft 1a Spiral Groove 2 Ball Nut 5 Sealing Member 5a Projection 5b1 Dividing Surface 5b2 Dividing Surface θ Spiral groove twist direction θ1 Inclination angle θ2 Inclination angle 8 Ball plunger 10 Garter spring

Claims (2)

[Scope of utility model registration request] 1. A ring-shaped seal member having a protrusion that fits into a spiral groove of a screw shaft is attached to an end of a ball nut to seal the inside of the ball nut. The seal member is divided into a plurality of parts. In addition, by elastically pressing the divided portion toward the inner diameter side, the fitting clearance between the protrusion and the spiral groove is made equal to or less than zero, and each divided surface of the sealing member is spiraled with respect to the axis. A ball screw seal device, wherein the groove is inclined in a twisting direction and further inwardly of the ball nut. 2. A ball nut, wherein a ring-shaped seal member having a protrusion that fits into a spiral groove of a screw shaft is attached to an end portion of a ball nut to seal the inside of the ball nut. While dividing into a plurality of from the end face facing the outer side to the middle part, and by elastically pressing the divided part to the inner diameter side, the fitting clearance between the protrusion and the spiral groove is zero or less, and A sealing device for a ball screw, wherein each divided surface of the seal member is inclined with respect to an axis in a twisting direction of the spiral groove and further inclined inward of the ball nut.