JPS6145097B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a positioning device that moves a movable table by rotating a feed screw.

A movable table that is guided by guide means provided on the base and is movable in one direction, a feed screw that is rotatably supported by a bearing on the base, and a nut that is screwed onto the feed screw. The positioning device usually fixes the nut directly to the movable table by means of fixing means, and transmits the axial movement of the nut to the movable table.

This conventional positioning device has the advantage of a simple structure, but since the nut of this device is fixed to the moving table, the axial movement of the feed screw and the moving table guided by the guide means In order to move the movable table smoothly using the feed screw, it is necessary that these two directions of movement match. but,
Since it is impossible to completely eliminate processing errors, installation errors, thermal displacement, etc. of each component, some differences between the two directions of movement are unavoidable, and conventional positioning devices Accurate positioning was difficult because the difference was absorbed by the play in the threaded portion of the feed screw and nut or the guide portion of the movable table.

In order to obtain accurate positioning using a conventional positioning device in which a nut is fixed to a moving table, if the play in the threaded part of the feed screw and nut, the guiding part of the moving table, etc. is eliminated, the feed screw will not move when the feed screw is rotated. There are parts where the rotational torque becomes heavier than necessary, which causes the problem that the rotational torque fluctuates and accurate positioning cannot be performed.

In general, feed screws have some eccentricity in the threaded part with respect to the shaft center, and in the bearing part that rotatably supports the feed screw on the base. It was difficult to move it.

Furthermore, when the nut is fixed directly to the moving table, there is a problem in that the vibrations of the motor etc. are directly transmitted to the moving table, causing the moving table to vibrate.

As a positioning device that improves this problem, a device in which the nut is supported by a leaf spring against the moving table has been proposed, but the conventional positioning device using a leaf spring does not support the nut in the axial direction The leaf spring was twisted in response to the thrust force. It is not desirable to make the leaf spring thicker or increase its width in the lateral direction in order to reduce the torsion of the leaf spring, since the leaf spring becomes stiffer and a large reaction force acts to absorb the deviation of the nut.

When such torsion occurs in the leaf spring, there is a disadvantage that for positioning that requires high-speed operation, there is a delay in the transmission of motion between the nut and the movable base, and vibrations are easily transmitted to the movable base.

Furthermore, the conventional positioning device has the disadvantage that a large number of man-hours are required for assembly and adjustment, since it is not possible to easily adjust from the outside to correct attachment defects between the moving table and the nut.

It is an object of the present invention to provide a positioning device that improves the above-mentioned drawbacks of conventional positioning devices, enables accurate positioning, and is easy to assemble and adjust.

In order to achieve this object, the present invention has a nut screwed onto a feed screw, which is attached to a linear member tensioned on a moving table, and the movement of the nut in the axial direction of the feed screw is controlled by a line loaded with tension. The transmission is rigidly transmitted to the moving table in the axial direction of the linear member, and the movement of the nut in the direction perpendicular to the axial direction of the feed screw is absorbed by the lateral deflection of the linear member. The gist of this invention is to improve the vibration absorbing properties of the movable platform by fitting a vibration absorbing member onto a linear member stretched over the movable platform.

Next, embodiments of the invention will be described with reference to the drawings.

Guide rails 2 and 3 having V-shaped rolling grooves for rolling elements are fixed to the base 1 so that the grooves for rolling elements face each other and are parallel to each other.

Guide rails 5 and 6 having the same shape as the guide rails 2 and 3 fixed to the base 1 are fixed to the movable table 4, and the guide rail 5 is attached to the guide rail 2, and the guide rail 6 is attached to the guide rail 3. They are facing each other.

Between the V-shaped rolling grooves of the opposing guide rails 2 and 5, rollers 9 held by a retainer 7 and whose axes are alternately rotated at right angles are fitted. Between the V-shaped rolling grooves of the opposing guide rails 3 and 6, rollers 10 held by a retainer 8 and whose axes are alternately rotated at right angles are fitted, and the movable base 4 includes guide rail 2,
3, it can be moved lightly in one direction relative to the base 1 by rolling of rollers 9 and 10.

The guide means for guiding the movable table 4 may be other known rolling guides, or may be sliding guides or static pressure guides other than rolling guides.

The feed screw 11 has an axis parallel to the moving direction of the movable table 4, and is rotatably supported on the base 1 by bearings 12, 13, and 14 about the axis.

The nut 15 is screwed onto the feed screw 11 and is movable in the axial direction of the feed screw 11 in response to the rotation of the feed screw 11.

The feed screw 11 may be a triangular screw or a trapezoidal screw, but it is preferable to use a ball screw in terms of accuracy, efficiency, etc. When using a ball screw, it is easy to apply preload using two nuts and eliminate backlash, and even when preload is applied to the threaded part, the rotational torque of the feed screw is small, so precise operation is possible. Become. Of course, a static pressure screw may be used as the feed screw.

Adjustment plates 1 are provided on both sides of the moving table 4 in the moving direction.
6 and 17 are fixed respectively, and this adjustment plate 1
Screws 18 or 19 fixed to both ends of one linear member 20 are loosely fitted into each of 6 and 17,
The linear member 20 is tightened by the tension nut 21 or 22.
is placed under tension by the movable table 4.

In this embodiment, an example is shown in which a thin member such as a wire is used as the linear member 20, but the linear member 20
If a wire diameter that allows a screw to be provided at the end of the wire member 0 can be used, the screws 18 and 19 are not necessary, and a male thread is provided directly at the end of the wire member, and the tension nuts 21 and 22 are used.
This allows the adjustment plates 16 and 17 to be stretched. Further, although one linear member 20 is used in this embodiment, a plurality of linear members 20 may be used.

The adjustment plates 16 and 17 can be slightly adjusted in their mounting positions so that the axes of the linear member 20 stretched over the movable table and the feed screw 11 are parallel to each other. The adjustment plates 16 and 17 may be provided only on one side of the movable table.

When tensioning the linear member 20 on the movable table 4, it is done by holding the screw 18 or 19 so that it does not rotate and tightening the tension nut 21 or 22. It may be provided.

A coupling member 23 is fixed to the upper surface of the nut 15, and the coupling member 23 is engaged with the linear member 20 at approximately the center of the linear member 20 in the longitudinal direction. The means for engaging the linear member 20 and the coupling member 23 may be brazing, crimp using screws, or the like.

In this embodiment, the coupling member 23 and the nut 15 are shown as separate bodies, but a structure in which the coupling member 23 and the nut 15 are integrated may also be used.

The vibration absorbing member 24 is made of an elastic material such as plastic or rubber, and is fitted over the linear member 20 to damp torsional or lateral vibrations of the linear member 20.

The positioning device of the present invention configured as described above has a feeder rotatably supported on the base 1, and a linear member 20 stretched on the movable base 4, which is supported on the base 1 and movable in one direction. Nut 1 screwed into screw 11
Since the connecting portion 23 fixed to the base plate 5 is engaged, a preload is applied to the guide portions of the base 1 and the movable table 4 and the threaded portions of the feed screw 11 and the nut 15 to ensure engagement without backlash. Even if it is adopted, Natsuto 1
5 is movable in the direction perpendicular to the axis of the feed screw 11 by the bending of the linear member 20;
1 is a linear member 20 loaded with tension in the axial direction.
Since it is rigidly connected to the movable base 4, the movement of the nut 15 corresponding to the rotation of the feed screw 11 can be accurately transmitted to the movable base 4, which has the effect of enabling precise positioning.

Further, since the tensioned linear member 20 is engaged with the coupling member 23 at the center, the operation of the nut 15 can be stably transmitted to the movable table 4 even in the face of temperature changes.

In addition, adjusting plates 16 and 17 are attached to the moving table 4,
A positioning device in which the position of the nut 15 relative to the movable table 4 can be adjusted from the outside has the advantage that assembly is easy.

Furthermore, a linear member 20 stretched on the moving table 4
In the case of a positioning device in which a vibration absorbing member 24 is externally fitted, it is possible to effectively absorb torsional or lateral vibration of the linear member 20, and the movement of the movable table 4 due to external vibration etc.
There is little vibration, and when the moving table 4 is suddenly stopped from high-speed operation, the time it takes for the moving table 4 to come to rest is short, and accurate positioning can be achieved in a short time.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a positioning device according to the present invention, and FIG. 2 is a cross-sectional view taken along the line A--A in FIG. 1... Base, 4... Moving table, 11... Feed screw, 15... Nut, 16, 17... Adjustment plate, 1
8, 19... Screw, 20... Linear member, 21, 2
2...Tension nut, 23...Connection member, 24...
Vibration absorbing member.

Claims (1)

[Claims] 1. A movable base 4 supported on a base 1 and movable in one direction, a feed screw 11 having an axis parallel to the moving direction of the movable base and rotatably supported on the base 1 by a bearing, Nut 15 screwed onto the feed screw
and a linear member 20 stretched on the moving table 4 in parallel with the axis of the feed screw, and the nut 1
5 and the linear member 20 are engaged with each other at a central portion in the longitudinal direction of the linear member 20.