JPS603414Y2 - Ball screw preload device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a preloading device for a hole screw, and in particular to a preloading device useful for a double-nut type ball screw in which two nuts are arranged for one screw shaft. .

Conventionally, preload devices for double-nut type ball screws include the first
Fix the nut to the housing using the flange of the nut. Fit the keys attached to the outer circumferential surfaces of the two nuts into the key grooves of the housing to align the nut's phase and stop it from rotating. Insert a wave washer or the like between the two nuts. Some are equipped with an elastic member such as a disc spring.

Such a device is very effective in that it uses an elastic member as a preloading means, but commercially available elastic members such as disc springs have approximately the same size as the outer diameter of the ball screw nut. However, if the disc spring is small, the disc spring may shift in the radial direction during assembly, which is particularly inconvenient when the nut is assembled into the housing as in the prior art example.

In addition, since a keyway is formed in the housing to align the phases of the two nuts and prevent them from rotating, the housing requires additional machining, and the mounting shape of the housing is also limited. was.

Furthermore, in such a conventional device, in order to ship it in a preloaded state like the conventional spacer method, a member for maintaining the preloaded state is required, which is troublesome.

The present invention is a simple preload device with a structure that eliminates the above-mentioned drawbacks by making the phasing and rotation prevention means between two nuts independent of the housing.
In a ball screw preloading device in which two nuts are arranged and an elastic member is interposed between the end faces of the two nuts, an annular member is attached to the outside of the elastic member, and the two nuts and the annular member are connected by a key member. It is characterized by a structure in which a retainer having a split on the outer periphery is placed over two fixed nuts in the direction of rotation, and the key member is held to the nut by the elastic force of the retainer. The details will be explained with reference to the drawings shown.

As shown in FIG. 1, this embodiment is a so-called double-nut type ball screw in which two nuts 2 and 3 are arranged on one screw shaft 1, and the nut 2 forms a flange 2a. and is fixed to the housing A by a tightening means T (for example, a bolt).

A plurality of elastic washers 4 such as wave washers are stacked and mounted between the end faces of the nuts 2 and 3.

On the outside of this elastic washer 4, an annular member 5 as shown in FIG.
is attached.

A key i5a is formed on the outer periphery of this annular member 5.

A key groove 2b is provided on the outer periphery of the opposite end surfaces of the nuts 2 and 3.
The nut 3 is rotated relative to the nut 2 to compress the elastic washer 4, and the key grooves 2b and 3a are set in line with each other at a predetermined tension preload amount position. The position of the key i5a of the member 5 is also aligned, and the key member 6 is placed in the groove thereof, thereby aligning the phases of the nuts 2 and 3 and preventing them from rotating.

Furthermore, a retainer 7 having a split as shown in FIG. 3 is placed over the outer periphery of the nuts 2 and 3.

The inner diameter of this retainer 7 is formed to be smaller than the outer diameter of the nut before it is placed over the nut, and when it is placed over the nut, the retainer 7 firmly holds the key member 6 and the annular member 5 in position due to its own elastic force. It is something to do.

Therefore, stainless steel or the like is effective for the retainer.

As described above, in the present invention, the elastic member interposed between two nuts is held by the annular member, and the key member that fixes the two nuts and the annular member in the direction of rotation is held by the elastic force of the retainer. It has a simple structure, does not require any extra processing on the housing side, and
It is easy to assemble and maintain and inspect, and since it is attached to the housing only by the flange of the nut, the shape of the housing is not limited and is excellent for practical use.

In the embodiment, the key member 6 is attached to one location on the outer periphery of the nut, but the same effect can be achieved even if the key member 6 is attached to two or three locations.

[Brief explanation of the drawing]

1 is a front sectional view showing an embodiment of the present invention, FIG. 2 is a perspective view showing the annular member shown in FIG. 1, and FIG. 3 is a perspective view showing the retainer shown in FIG. 1. Explanation of symbols, 1... Screw shaft, 2, 3...
- Nut, 4... Elastic member, 5... Annular member, 6... Key member, 7... Retainer, A... Housing, T...Tightening means, 2a...Flange, 2b, 3a. 5a...Keyway.

Claims (1)

[Scope of utility model registration request] In a ball screw preloading device in which two nuts are arranged for one screw shaft and an elastic member is interposed between the two nut end faces, an annular member is attached to the outside of the elastic member,
Two nuts and an annular member are fixed in the direction of rotation by a key member, a retainer having a split is placed on the outer periphery of the two nuts, and the key member is held to the nut by the elastic force of the retainer. A ball screw preload device featuring: