JP2000018358A - Axial feed mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To integrally constitute a guide portion and a feed adjusting portion by disposing a feed screw in a feed pipe engaging with an inner periphery of a ball bush and penetrating through the ball bush. SOLUTION: A feed pipe 6 is adjusted to a ball bush 2 and is disposed so as to penetrate through an inner space of the ball bush 2. A screw nut 7 is provided in the feed pipe 6 eccentrically against the feed pipe 6. Then, a feed screw shaft 8 having an appropriate screw engaging relationship with the screw nut 7 is penetrated through the screw nut 7. When the feed screw shaft 8 is turned, the screw nut 7 is displaced and accompanying with the displacement, the feed pipe 6 is relatively moved to the ball bush 2 to feed reciprocating parts connected to the feed pipe 6. At the time of a rectilinear motion, since a center of the feed screw shaft 8 and the screw nut 7 is left from the center of the feed pipe, i.e., the ball bush 2 by some distance, the feed pipe 6 does not rotate in the ball bush 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feed mechanism for reciprocating a saddle, a carriage, and a table of a machine tool, for example.

[0002]

2. Description of the Related Art A mechanism for giving a linear motion to a part requiring reciprocating motion guidance, such as an XY table, is basically composed of a guide part for guiding the above-mentioned part while supporting it, And a screw feed which is arranged at a predetermined interval in parallel with the screw feed. As the guide portion, for example, a linear bearing typified by a simple rail-shaped guide or a ball bush is used. As the screw feed, a combination of a rack and a pinion, a combination of a rack and a worm, or a ball screw is used. The feed may be realized by a hydraulic cylinder and a piston instead of the screw feed.

For example, as shown in FIGS. 3a and 3b,
With respect to a feed screw 1 for linearly moving a reciprocating part (not shown) by a predetermined distance,
There is known a feed mechanism in which two ball bushes 2 are arranged, and two parallel shafts 3 penetrating each ball bush 2 are arranged. The two shafts 3 are also parallel to the feed screw 1, and when the feed screw 1 is turned, the reciprocating parts (not shown) connected to the shafts are shown in FIG.
It becomes possible to move up and down in b. Similarly, as shown in FIG. 4, a feed mechanism having a rail-shaped guide 4 having a parallel relationship with the feed screw 1 in the axis is also widely used.

By providing the guide portion and the screw feed in parallel with each other, the reciprocating part is held parallel to a plane including the guide portion and the screw feed, and rotated in a direction perpendicular to the plane, in other words. This prevents the rotation about the axis of screw feed as the rotation axis.

[0005]

However, separately arranging the two members, the guide portion and the screw feed, restricts the space saving. Also, the reciprocating parts supported by these are subject to weight restrictions due to the relatively small guide portion and screw feed.

SUMMARY OF THE INVENTION An object of the present invention is to propose a simple and small-sized axial feed mechanism which can apply linear motion to a relatively large reciprocating part.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above problems by providing a feed pipe fitted in a ball bush and penetrating the ball bush, a screw nut eccentrically arranged in the feed pipe, and an engagement with the screw nut. And a feed screw shaft, which is provided with an axial feed mechanism.

It is more effective if the outer peripheral surface of the screw nut is eccentric so as to be in contact with the inner peripheral surface of the feed pipe.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on an example shown in the drawings. FIG. 1 is a sectional view showing the basic components of an axial feed mechanism according to an example of the present invention. A feed pipe 6 is provided so as to fit through the inner space of the ball bush 2 so as to penetrate therethrough. In the feed pipe 6, a screw nut 7 is provided eccentrically with respect to the pipe. A feed screw shaft 8 having an appropriate screw fitting relationship with the screw nut 7 penetrates the screw nut 7.

[0010] As shown in FIG.
When the feed screw shaft 8 also supported is rotated by a driving device (not shown), the screw nut 7 fixed in the feed pipe 6 is displaced, and the feed pipe 6 is accordingly moved with respect to the ball bush 2. 2 reciprocally move in the left-right direction, and reciprocating parts (not shown) connected to the feed pipe 6 are fed left and right. During this linear motion, the center of the feed screw shaft 8 and the screw nut 7 is separated from the feed pipe 6 and thus the center of the ball bush 2 by a certain distance.
The feed pipe 6 does not rotate in the ball bush 2. The larger the amount of eccentricity is, the more effective the rotation prevention is, and the most effective is that the outer peripheral surface of the screw nut is in contact with the inner peripheral surface of the feed pipe.

[0011]

According to the present invention, there is provided a ball bush and a feed pipe fitted into the ball bush and penetrating the ball bush, and the feed screw portion is disposed in the feed pipe. The guide portion and the feed adjustment portion are integrally formed, and can be simplified, and a reasonable size can be ensured. Then, a screw nut is eccentrically fixed in the feed pipe, and a feed adjusting portion is formed by engagement of the screw nut and the feed screw shaft. Therefore, the feed pipe in the ball bush, in other words, the feed adjusting portion rotates. I won't.

By integrating the guide portion and the feed adjusting portion as described above, it is not necessary to use a particularly complicated mechanism or component for sealing the feed adjusting portion which is weak against dust and the like. Furthermore, it has become possible to manufacture at a lower cost than the conventional feed mechanism.

[Brief description of the drawings]

FIG. 1 is a cross sectional view showing a main configuration of an axial feed mechanism according to the present invention.

FIG. 2 is a schematic longitudinal sectional view of the axial feed mechanism shown in FIG. 1;

3A and 3B are schematic views showing a conventionally known feed mechanism, in which FIG. 3A is a cross-sectional view and FIG. 3B is a vertical cross-sectional view.

FIG. 4 is a schematic cross-sectional view showing a conventionally known feed mechanism according to another configuration.

[Explanation of symbols]

 2 Ball bush 6 Feed pipe 7 Screw nut 8 Feed screw shaft

Claims (2)

[Claims] 1. A feed pipe fitted in a ball bush and penetrating the ball bush, a screw nut eccentrically arranged in the feed pipe, and a feed screw shaft engaged with the screw nut. Axial feed mechanism. 2. The axial feed mechanism according to claim 1, wherein an outer peripheral surface of the screw nut is in contact with an inner peripheral surface of the feed pipe.