JPS61211567A - Ball screw and nut supporting device - Google Patents

Abstract

PURPOSE:To enable automatic correction of axial distortions between a ball screw and a ball nut by placing tables between a casing and a holder installed at a driven member so that the grooves made in the diametral direction are to cross one another at a right angle. CONSTITUTION:A ball nut is contained in a cylindrical holder 6, the holder 6 is loosely armored by a casing 8, and the casing 8 is fixed to a driver member. Two pairs of tables 13, 14, 15 with grooves 9, 10, 11, 12 in the diametral direction are placed between the casing 8 and the holder 6 so that each groove 9, 10, 11, 12 in the diametral direction is to cross one another at a right angle. A ball 5 is placed between the grooves 9, 10, 11, 12 of each table 13, 14, 15, and pinching pressure is put on the ball 5 by a spring 16. Then the ball screw 1 is jointed universally to that automatic correction of the axial distortion between the ball screw 1 and the ball nut 2 can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a device for supporting a ball screw/nut on a driven member in order to screw-feed the driven member using the ball screw/nut.

[Background of the invention]

Screw feed mechanisms are widely used as driving means for precision equipment, and ball screws and ball nuts are used when precision is particularly required.

When using the above ball screw/nut as a driving means, the ball screw and ball nut must be supported concentrically with ultra-precision. FIG. 5 is an explanatory diagram of the above-mentioned concentric bearing.

For convenience of explanation, three orthogonal axes x, y, and z are assumed.

The ball screw 1 and the ball nut 2 need to be completely concentric with respect to the X axis. That is, (al) The center lines of both members must not deviate in the Y-axis direction.

(b) Similarly, there is no deviation in the X-axis direction.

(C) Similarly, there should be no deviation in the direction of the force at angle θy around the Y-axis.

(dl Similarly, there should be no deviation in the angle θ2 direction around the X axis.

In addition to satisfying the above conditions (a) to (d), both members must have no backlash in the X-axis direction and θX around the X-axis.
It must be supported without any directional play.

However, it is extremely difficult from a practical technical standpoint to support a ball screw/nut with super precision and satisfy all of the above conditions.

For this reason, there is a strong desire to develop a device with a self-aligning function for supporting the ball screw/nut on the driven member.

[Purpose of the invention]

The present invention has been made in response to the above-mentioned demands, and aims to provide a support device with a simple configuration that can automatically correct misalignment between a ball screw and a ball nut. Specifically, it is possible to automatically correct misalignment of a stepped shape in a direction perpendicular to the axis of the ball screw, and misalignment of a surface runout in a direction perpendicular to the axis of the ball screw.
Moreover, it is an object of the present invention to provide a device with a simple structure that can support a ball nut without play in the axial direction of the ball screw (and without play around the axis of the ball screw).

[Summary of the invention]

FIGS. 6 and 7 are explanatory diagrams of the basic principle of the present invention created to achieve the above object.

Each of the two tables 3.4 has a diametrical V-shaped groove 3a.
, 4a are provided, the 7-shaped grooves are made to face each other, and the two tables 3 and 4 are placed on top of each other in the X-axis direction via the ball 5, so that the two tables 3 and 4 are
Align it to the Y plane. In this way two tables 3.4
While applying pressure as indicated by arrows A and B, one of the two tables 3.4 is used as a driving plate and the other as a driven plate.

In a state where the V-shaped groove 3a faces the Y-axis direction as shown in the figure, the balls 5 move within the V-shaped grooves 3a and 4a to absorb the misalignment of the stepped shapes of both tables 3.4 in the Y-axis direction. be done.

Further, the misalignment of the surface runout shape in the angle θy force direction around the Y axis is absorbed by the seesaw movement with the ball 5 as the fulcrum.

When two sets of the units shown in the principle diagrams described above (Figures 6 and 3) are placed one on top of the other and arranged with the single-shaped grooves perpendicular to each other, there will be a difference in level in the Y-axis direction and a difference in level in the X-axis direction.

It is possible to absorb vibrations around the Y-axis and around the X-axis. Then, the rotation around the X axis is performed via the ball 5.
The power is transmitted through the grooves 3a and 4a.

In order to achieve the above object based on the above principle, a ball screw/nut support device according to the present invention supports a ball nut on a driven member, and rotates a ball screw screwed onto the ball nut. The means for driving the driven member in the axial direction of the ball screw comprises a cylindrical holder that accommodates the ball nut, and a cylindrical shape with a top and bottom that fits loosely into the holder. A casing is provided, a ball screw is inserted gently into through holes provided in the top and bottom surfaces of the casing, and two pairs of
A table provided with a diametrical groove is interposed, and the two pairs of tables are configured so that the diametrical grooves are orthogonal to each other, and the diametrical grooves of each pair of tables are opposed to each other, and a ball is inserted between them. The casing configured as described above is attached to the driven member, and a spring means is provided for biasing the holder toward the top or bottom of the casing, and the casing is interposed between the two pairs of tables. It is characterized by applying a clamping force to the mounted ball and locking relative rotation between the holder and the ball nut.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the ball screw/nut support device of the present invention, FIG. 2 is a cross-sectional view taken along the line nn in FIG. 1, and FIG. Figure 4 is the same <I'/
-rV sectional view.

1 is a ball screw, and 2 is a ball nut.

A cylindrical holder 6 is configured to house the ball nut 2.

A key 7 locks the relative rotation of both members.

A capped cylindrical casing 8 that fits loosely onto the holder 6 is constructed, and the casing 8 is attached to a driven member (not shown).

3a and 3b are a top plate and a bottom plate, but the casing 8 is functionally symmetrical and there is no need to distinguish between the top plate and the bottom plate. In this column, top plate $a, bottom plate 8b
is a name for convenience of explanation. Through holes 8a-+ and 8b-+ are provided in the top plate 8a and the bottom plate 8b, respectively, and are fitted onto the ball screw 1 with an appropriate clearance.

Two pairs of tables with V-shaped grooves cut in the diametrical direction are constructed as follows.

9, 10, 11, and 12 are two pairs of figure-7 grooves provided on two pairs of tables. Figure 7 groove 9 and 10. 1.1 and 12 form two pairs facing each other in the same direction, and a ball 5 is interposed between each pair.

13 is a table provided with a 7-shaped groove 9, and a casing 8
It is fixed to the top surface 8a of.

14 is a table provided with a figure-7 groove 10 and a figure-7 groove 11;
This is a table that is integrated with a table provided with.

When implementing the present invention, among the two pairs of tables (total of four tables),
There is no hindrance to connecting the two intermediate sheets into one body as in this example. Alternatively, the two tables may be configured separately and connected. In either case, one pair of V-shaped grooves and another pair of V-shaped grooves are arranged so as to be perpendicular to each other.

Reference numeral 15 denotes a table provided with a ■-shaped groove 12, which is attached to the holder 6.

A coil spring 16 is compressed and interposed between the holder 6 and the casing bottom plate 8b so as to urge the holder 6 toward the top plate 8a of the casing.

According to the device configured as described above, as shown in FIG. 1 and as is clear from comparing FIG. 2 and FIG. 10 and 11.12 form a right angle. Therefore, due to the transfer of the ball 5 that engages with the V-shaped groove, the ball screw 1 and the ball nut 2
The misalignment of the uneven shape in the Y-axis direction, the misalignment of the uneven shape in the Z-axis direction, the misalignment of the surface run-out shape around the Y-axis, and the misalignment of the surface run-out shape around the Z-axis are self-aligned, and they come into contact with each other and become distorted. The ball nut 2 is prevented from rotating relative to the casing 8, and the ball nut 2 is prevented from rotating relative to the casing 8.

〔Effect of the invention〕

As explained above, when the present invention is applied, the ball nut can be automatically aligned and supported with respect to the ball screw. In other words, it is possible to automatically correct the misalignment of the stepped shape in the direction perpendicular to the axis of the ball screw and the misalignment of the surface runout in the direction perpendicular to the axis of the ball screw. This provides an excellent practical effect in that the ball nut can be supported without play in the axial direction and without play around the axis of the ball screw.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, Fig. 2 is a cross-sectional view taken along the line ■-■ of Fig. 1, Fig. 3 is a cross-sectional view taken from Fig. 1, and Fig. 4 is a cross-sectional view taken along the line IV-IV of Fig. 1. It is. FIG. 5 is an explanatory diagram of concentricity between a ball screw and a ball nut. 6 and 7 are explanatory diagrams of the basic principle of the present invention. 1... Ball screw, 2... Ball nut, 3, 4.
...Table, 5...Ball, 6...Ball nut holder, 7...Key, 8...Casing, 8a...
...Top plate, 8b...Bottom plate, 9.10.11.
12-V-shaped groove, 13° 14, 15... table.

Claims (1)

[Claims] A means for supporting a ball nut on a driven member and rotating a ball screw screwed onto the ball nut to drive the driven member in the axial direction of the ball screw,
A cylindrical holder that accommodates the ball nut is provided, and a cylindrical casing with a top and a bottom that fits loosely on the holder is provided, and transparent parts provided on the top and bottom surfaces of the casing are provided. Insert the ball screw gently into the hole,
interposing a table provided with two pairs of diametrical grooves between the top or bottom surface of the casing and the holder;
The two pairs of tables are constructed so that their diametrical grooves are orthogonal to each other, and the diametrical grooves of each pair of tables are faced to each other with a ball interposed therebetween, and the casing constructed as described above is covered. A spring means is attached to the drive member and urges the holder toward the top or bottom of the casing to apply a squeezing force to the balls interposed between the two pairs of tables, and to compress the holder and the balls. A ball screw/nut support device characterized by locking relative rotation with the nut.