JPH022506B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Technical Field The present invention relates to a slide table device in which a slide table is moved by a feed mechanism consisting of a feed screw and a nut, and particularly relates to an improvement in the joint between the nut and the slide table.

The present invention is applicable not only to screw-type feed mechanisms, but also to the connection between a rod and a slide table in a cylinder type, or the connection between a movable part of a linear motor and a slide table.

(b) Prior art A movable base supported by a guide surface provided on a base and capable of reciprocating in one direction, and an axis parallel to the direction of movement of the movable base, capable of rotating about this axis in the axial direction. It is equipped with a feed screw that cannot be moved and is supported on a base, and a nut that is screwed onto the feed screw, and is moved by transmitting the axial displacement of the nut corresponding to the rotation of the feed screw to the movable table. 2. Description of the Related Art Moving table devices in which a table has a predetermined linear movement accuracy or a predetermined movement accuracy are often used in machine tools, measuring instruments, and the like.

In this moving table device, the nut is fixed to the moving table, so the nut moves along the guide surface of the base that guides the moving table, and the feed screw that screws into this nut is properly fitted into the nut. In order to maintain the alignment, it is necessary that the axis of movement of the nut and the axis of the feed screw match correctly, but in the case of a moving table device that requires extremely high accuracy, It is difficult to align the two axes accurately from the viewpoint of both machining accuracy and assembly accuracy.

In other words, in the conventional moving table device in which the nut is fixed to the moving table, even if the guide surface that guides the moving table is made precise and a precision feed screw is used, the straightness of the guide surface that guides the moving table and the difference between the guide surface and the Parallelism with the feed screw, eccentricity of the feed screw, or installation error between the feed screw and nut, etc., will always exist even if it is slight, and the guide surface that guides the moving platform and the threaded part between the nut and the feed screw will always exist. If a precision screw connection is adopted that eliminates backlash, the screw connection will be defective due to misalignment of the axes of the nut and feed screw, and the rotational torque of the feed screw will fluctuate, making it impossible to obtain accurate movement of the moving table. There is.

As a countermeasure to the above-mentioned conventional problems, a device as disclosed in Japanese Patent Application Laid-Open No. 57-25559 has been proposed.

As shown in FIG. 1, a nut 25 is provided with a collar 26, and a housing 30, which is loosely fitted onto the nut and has a bearing surface opposing the collar 26, is fixed to a table. . By supplying pressurized fluid between this bearing surface and the bearing surface of the housing to create a static pressure bearing, rigidity in the axial direction is obtained, and the above-mentioned deviation in parallelism and whirling of the screw shaft are avoided. It is something to do. Further, in this device, in order to prevent rotation of the nut portion, a bellows 46 is fixed to the table, and the end portion of the nut 25 is fixed to the bellows 46.

In fields where the speed unevenness when moving the table is required to be less than a few percent, it is first necessary that the pitch error and fluctuation of the feed screw be small, but in order to manufacture such a feed screw, for,
For forging, it is necessary that the screw shaft be as short as possible. However, in the conventional device described above, the bellows is attached in the longitudinal direction of the shaft, so in order to ensure a constant stroke, the screw shaft must be made longer by the length of the bellows.
This is one of the factors that prevents improvement in feed accuracy.

Furthermore, in a hydrostatic bearing, particularly an air static pressure bearing, in order to increase the rigidity of the bearing portion, it is necessary to increase the bearing area. In the case of the above conventional device, if the area of the portion of the flange surrounded by the annular groove is to be increased for this reason, it becomes necessary to increase the diameter of the flange. However, as this diameter increases, the distance between the center line of the screw shaft and the table increases, and the center of the screw shaft also comes to a higher position than the base surface of the device, which increases the risk of external vibration and housing. There are drawbacks such as the inclination of the 30 to the nut, which adversely affects speed unevenness, and the addition of minute vibrations.

C. Purpose of the Invention The present invention aims to solve the above-mentioned problems in conventional devices of this type.

That is, one object of the present invention is to provide a slide table device having a structure that allows effective use of the axial length of the feed screw.

Another object of the present invention is to provide a slide table device in which the distance from the center line of the feed screw to the slide table is short and vibrations are small.

D. Structure of the Invention In order to achieve the above object, the slide table device of the present invention moves the slide table 7 in the axial direction of the feed screw 14 using a feed mechanism consisting of the feed screw 14 and the nut 1 screwed into the feed screw 14. As a sliding table device,
A movable plate 2 whose both sides are connected to the nut 1 with receiving surfaces perpendicular to the axis of the feed screw 14, and the feed screw 1.
4 have receiving surfaces 4a and 5a facing each receiving surface of the movable plate 2 on both sides in the horizontal direction, and are fixed to the slide table 7 with spacers 6 in between and separated from each other in the axial direction with the movable plate 2 in between. In order to form a hydrostatic bearing by supplying pressurized fluid between the pair of receiving plates 4, 5, the receiving surfaces 4a, 5a of each receiving plate 4, 5, and the receiving surface of the movable plate 2 opposing thereto. Means 9, 11a~
11c, and means 12, 12a to 12d for elastically and adjustablely positioning the movable plate 12 in the horizontal direction from both ends thereof.

E. Effects of the Invention According to the present invention, since the rotation of the nut is prevented by horizontal support without relying on bellows, etc., the distance from the axis of the feed screw to the table can be shortened, and as a result, the height of the table from the base can be reduced. can be made relatively low. Therefore, the adverse effects caused by external vibrations and the inclination of the housing with respect to the movable plate can be suppressed to a minimum. In addition, since the bellows that runs along the axial direction of the screw like a conventional device is not used, the axial length of the screw can be used effectively. It is possible to perform accurate feeding.

F. Embodiments Hereinafter, embodiments of the present invention shown in FIGS. 2 to 7 will be described.

A nut 1 is fixed to a movable plate 2. A pair of receiving plates 4 and 5 face each other with this movable plate 2 in between and a spacer 6 between them, and the pair of receiving plates 4 and 5 and the spacer 6
are combined to form a housing 3. A spacer 6 is interposed between the receiving plates 4 and 5 and below the movable plate 2, which is slightly (preferably 5 to 50 μm) thicker than the movable plate. Note that the receiving plate 5 is a slide table 7.
It is fixedly installed.

Both side surfaces of the moving plate 2 serve as receiving surfaces perpendicular to the axis of the feed screw 14, and the receiving plates 4 and 5 have receiving surfaces 4a and 5a facing these receiving surfaces of the moving plate 2. Receiving surface 4
a, 5a, as shown in FIGS. 6 and 7,
A square-shaped groove 11a is formed, and a hole 11b is provided in the center thereof. This hole 11b is connected to a supply port 9 which communicates with a source of pressurized fluid by means of an air supply hole 11c.
(Figure 4). Note that the same effect can be obtained by using nozzles (not shown) distributed on the receiving surfaces 4a and 5a instead of the square-shaped groove 11a. Thus, when pressurized fluid is supplied to the supply port 9, the moving plate 2 and the housing 3 form a hydrostatic bearing.

As shown in FIG. 5, spaces 13 exist above and below the movable plate 2. Moreover, the end surface of the moving plate 2 is
It is pressed horizontally from both sides via the presser plate 12 by a spring 12a. A guide rod 12b is attached to this holding plate 12, so that the holding plate 12 can only move horizontally about the feed screw 14 without rotating or tilting. Also, the spring 1 is inserted from the outside via the bottom plate 12c using the adjusting screw 12d.
By adjusting the pressing force of 2a, the moving plate 2
The horizontal position can be adjusted.

With the above configuration, when pressurized fluid is supplied to the supply port 9, the movable plate 2 is supported by static pressure within the housing 3, and the nut 1 and the movable plate 2 fixed thereto are aligned with the axis of the feed screw 14. When moving in this direction, the slide table 7 is also driven accordingly. At this time, Natsu 1 and slide table 7
If the mechanism is directly fixed, minute vibrations due to the dimensions of the screws, surface precision of the screw surfaces, minute vibrations coming from the joint between the motor and the screws, etc. will occur as small irregularities in the table movement speed. In the invention, these are absorbed by the hydrostatic bearing section, making it possible to achieve extremely smooth driving.

Furthermore, even if a rotational force acts on the nut 1 as the feed screw rotates, the nut 1 will not move because both end surfaces of the movable plate 2 are supported by pressure at a position far away from the feed screw in the horizontal direction. There is no rotation. Furthermore,
When the feed screw 14 rotates, the axis may run out,
Even if there is a deviation in parallelism between the slide table and the feed screw, the movable plate 2 is supported by static pressure, so
Because it can move freely in a plane perpendicular to the axis of the feed screw 14 without rotating around the axis,
Good feeding accuracy can be obtained without adversely affecting the straightness of the slide table.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a conventional device, FIG. 2 is a front view of main parts of a slide table device according to the present invention, and FIG.
4 is a sectional view taken along the - line in FIG. 2, FIG. 5 is a sectional view taken along the - line in FIG. 3, and FIG. 6 is a sectional view taken along the - line in FIG. 4. , FIG. 7 is a sectional view taken along the - line in FIG. 2, and FIG. 8 is an exploded perspective view of the components shown in FIG. 4 (excluding the slide table 7). 1... Nut, 2... Moving plate, 3... Housing, 4, 5... Receiving plate, 4a, 5a... Receiving surface, 6...
... Spacer, 7 ... Slide table, 9 ... Supply port, 11a ... Field-shaped groove, 11b ... Hole, 1
1c...Air supply hole, 12...Press plate, 13...Space, 14...Feed screw.

Claims (1)

[Scope of Claims] 1. A slide table device in which a slide table is moved in the axial direction of the feed screw by a feed mechanism consisting of a feed screw and a nut screwed into the feed screw, with both sides facing the axis of the feed screw. A moving plate that is connected to a nut without a vertical bearing surface, and a receiving surface that faces each bearing surface of the moving plate on both sides of the feed screw in the horizontal direction, and are separated from each other in the axial direction with a spacer in between and with the moving plate in between. a pair of receiving plates fixedly fixed to the slide table in a fixed state, a means for supplying pressurized fluid between the receiving surface of each receiving plate and the receiving surface of the opposing moving plate to form a hydrostatic bearing; and means for horizontally elastically and adjustablely positioning the movable plate from both ends thereof. 2. The means for positioning the movable plate includes a guide rod that is horizontally slidably fitted in an appropriate position on the slide table side and abuts the movable plate at one end, and a spring that presses the guide rod toward the movable plate; The slide table device according to claim 1, further comprising an adjustment screw for adjusting the pressing force by the spring.