JP2004286710A - Method and apparatus for attaching linear scale - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow using of a linear scale for a stage where motion perpendicularity changes or is worse. <P>SOLUTION: The scale 6 of a linear scale 4 is attached to a stand 10 using an attaching plate 30 which is independent of a base plate 12 and has high perpendicularity. Displacement of a top table 16 is transmitted to a head 8 of the linear scale 4 through a leaf spring 34. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for mounting a linear scale, and in particular, comprises a linear guide and a ball screw, and is suitable for use in a machine tool or the like. The present invention relates to a method and an apparatus for mounting a linear scale suitable for use in a straightness control stage, for measuring the displacement of a top table moving on a base plate having a changed or poor straightness.
[0002]
[Prior art]
When high-precision positioning accuracy is required for a stage such as a machine tool, a linear scale is used. In a stage using a linear motor, feedback control using a linear scale is essential.
[0003]
[Problems to be solved by the invention]
When this linear scale is used for a stage with poor straightness or a stage for controlling the straightness movement accuracy of the stage to be uneven (referred to as a straightness control stage), the linear scale 4 is used as a sensor head unit shown in FIG. Since the pitching error allowed in the azimuth direction with respect to the scale portion 8 of FIG. 8 is extremely small (about several minutes in angle, the other vertical direction, opening direction, yawing, and rolling directions are insensitive), a scale reading error occurs. Had problems.
[0004]
On the other hand, as related to the present invention, Patent Literature 1 discloses that a static pressure gas bearing can control a supply pressure of a static pressure gas bearing to maintain a posture such as a straightness of a movable body such as a slide table with high accuracy. Although a pressurized gas bearing device is described, nothing is described about mounting a linear scale.
[0005]
[Patent Document 1]
JP 2000-337375 A
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has as its object to make it possible to use a linear scale with high accuracy on a straightness control stage or a stage with poor straightness.
[0007]
[Means for Solving the Problems]
The present invention provides a method for mounting a linear scale for measuring a displacement of a top table moving on a base plate whose straightness changes or is inferior, and mounting the scale portion of the linear scale independently of the base plate, with a high straightness. The present invention has solved the above-mentioned problem by attaching a displacement of the top table to a head portion of the linear scale via a leaf spring while attaching to a gantry by a plate.
[0008]
The present invention is also a linear scale mounting device for measuring the displacement of a top table moving on a base plate whose straightness changes or is inferior, for mounting the scale portion of the linear scale to a gantry, The object is achieved by providing a mounting plate having high straightness independent of a base plate and a leaf spring for transmitting the displacement of the top table to a head portion of the linear scale.
[0009]
Further, the head portion is supported by a linear guide mounted on the mounting plate.
[0010]
The present invention also provides a straightness control stage comprising a linear scale attached by the above device.
[0011]
Another object of the present invention is to provide a processing apparatus including the straightness control stage.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention applied to attachment to a straightness control stage will be described in detail with reference to the drawings.
[0013]
As shown in FIG. 2, the straightness control stage to which the present invention is applied has a base plate 12 whose center is fixed to the gantry 10 and both ends of which are displaceable, a linear guide 14 fixed to the base plate 12, A top table 16 that reciprocates on the linear guide 14 in a direction indicated by an arrow A in the figure, a servo motor 18 and a ball screw 20 that are driving means for driving the top table 16, and mounts at both ends of the base plate 12. For example, pressurizing devices 22 provided at the four corners of the base plate 12 for changing the interval between the base plate 12 and the four corners of the base plate 12 for detecting displacement of the four corners of the base plate 12 by the pressurizing device 22. And four displacement sensors 24 provided respectively.
[0014]
As the pressure device 22, for example, an air cylinder or a hydraulic cylinder can be used, and the pressure is adjusted to obtain a predetermined displacement.
[0015]
As the displacement sensor 24, for example, an electric micrometer, an eddy current sensor, or the like can be used.
[0016]
If it is desired to obtain a desired straightness, for example, if the straightness of the component fixed on the top table 16 is to be concave, the top table 16 is to be moved to a convex as shown by a solid line B in FIG. The four corners of the base plate 12 are displaced downward as shown by the arrow B in FIG. 2 by the pressing device 22 to elastically deform the base plate 12. At this time, the pressure of the pressurizing device 22 is adjusted so that the displacement amount detected by the displacement sensor 24 becomes a predetermined amount.
[0017]
Conversely, when it is desired to make the straightness of the component fixed on the top table 16 convex, the straightness of the stage is concave as shown by the broken line C in FIG.
[0018]
In the present embodiment, as shown in FIG. 4, the scale of the linear scale 4 is not affected by the deflection of the base plate 12 and the displacement of the top table 16 in the pitching direction. The mounting plate 30 of the part 6 is mounted on the gantry 10 at a portion separated from the base plate 12. The sensor head 8 is supported by a linear guide 32 mounted on a scale mounting plate 30.
[0019]
Further, the top table 16 of the stage and the sensor head section 8 are connected by an L-shaped leaf spring 36 via a stay 34, for example. As the leaf spring 36, for example, a stainless steel plate or spring steel can be used.
[0020]
In this manner, since the leaf spring 36 absorbs the vertical movement caused by the movement of the top table 16, regardless of the deflection of the base plate 12 and the change in the straightness of the movement of the top table 16 (corresponding to the change in the azimuth direction). Since the sensor head unit 8 and the scale unit 6 always face each other, a linear scale reading failure does not occur. In addition, since the leaf spring 36 has high rigidity in the stage movement direction A, the movement direction positioning accuracy does not deteriorate.
[0021]
In the above-described embodiment, the center of the base plate 12 of the straightness control stage is fixed to the gantry 10 and both ends can be displaced in the vertical direction by the pressurizing device 22, but the method of displacing the base plate 12 is as follows. However, the present invention is not limited to this. Conversely, it is also possible to fix both ends of the base plate 12 to the gantry 10 and provide a pressing device 22 at the center so that the center can be displaced in the vertical direction. In this case, it is desirable that the linear scale mounting plate 30 is also fixed to the gantry 10 at both ends.
[0022]
Further, the configuration of the driving means is not limited to the combination of the servo motor and the ball screw. For example, a linear motor can be used. The shapes of the stays 34 and the leaf springs 36 are not limited to the L-shape. For example, two I-shaped leaf springs may be combined at right angles.
[0023]
Further, in the above embodiment, the present invention is applied to the straightness control stage in the machine tool. However, the application object of the present invention is not limited to this. It is clear that the present invention can be similarly applied to a straightness control stage for mounting the same or a linear scale attached to a stage having a poor motion straightness.
[0024]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to use a linear scale also for the stage whose motion straightness changes or whose motion straightness is inferior.
[Brief description of the drawings]
FIG. 1 is a perspective view for explaining a problem of a linear scale. FIG. 2 is a perspective view showing an entire configuration of an embodiment of the present invention. FIG. 3 is a diagram showing a deflection of a base plate in the embodiment. ] Cross-sectional view showing the structure of the linear scale mounting part [Explanation of reference numerals]
4 Linear scale 6 Scale part 8 Sensor head part 10 Stand 12 Base plate 16 Top table 30 Scale mounting plate 32 Linear guide 34 Stay 36 Leaf spring

Claims (5)

When installing a linear scale to measure the displacement of the top table moving on the base plate whose straightness changes or is inferior
The scale portion of the linear scale is independent of the base plate, and is attached to the gantry by a highly straight mounting plate.
A method of mounting a linear scale, wherein the displacement of the top table is transmitted to a head portion of the linear scale via a leaf spring. A linear scale mounting device for measuring a displacement of a top table moving on a base plate whose straightness changes or is inferior,
For mounting the scale portion of the linear scale to the gantry, independent of the base plate, a high straightness mounting plate,
A leaf spring for transmitting the displacement of the top table to the head portion of the linear scale,
A mounting device for a linear scale, comprising: The linear scale mounting apparatus according to claim 2, wherein the head portion is supported by a linear guide mounted on the mounting plate. A straightness control stage comprising a linear scale attached by the device according to claim 2. A processing apparatus comprising the straightness control stage according to claim 4.

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