JP2001107963A - Hydrostatic bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rigidity of a hydrostatic bearing and stability in relation to fluctuation of load. SOLUTION: A slot clearance hs between an adjusting sleeve 1 and a fixed sleeve 2 and a clearance hs1 between the upper cylindrical surface of the adjusting sleeve 1 and the fixed sleeve 2 are taken as slot throttles. The adjusting sleeve 1 is attached to a base 5 through a piezoelectric element 3. When the clearance Δh is decreased by the increase of load, the decrease is detected by a displacement gauge 9, voltage corresponding to the displacement amount is applied to the piezoelectric element 3, the piezoelectric element 3 is contracted by Δh, and the fluid resistance is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic bearing using gas or liquid as a lubricant.

[0002]

2. Description of the Related Art Conventionally, in a static pressure gas bearing, the rigidity of the bearing is improved by devising a shape of an air supply throttle for supplying gas.

[0003]

However, because of the passive type, infinite bearing rigidity could not be obtained even with a slow load change. Further, there is a disadvantage that self-excited vibration is apt to occur when the bearing rigidity is improved.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to limit the high bearing rigidity and the high rigidity by controlling the slot interval of the slot-shaped air supply throttle of the hydrostatic bearing. An object of the present invention is to provide a hydrostatic bearing capable of obtaining infinite bearing rigidity.

[0005]

According to the hydrostatic bearing of the present invention, the slot throttle is composed of a fixed sleeve and an adjusting sleeve, and the adjusting sleeve is moved to make the slot interval variable and adjust the fluid resistance. In this method, the rigidity of the bearing is extremely increased by controlling the pressure in the throttle portion and the flow rate of the bearing according to the load fluctuation.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A hydrostatic bearing according to the present invention
By making the slot interval of the slot-shaped air supply throttle variable and adjusting the fluid resistance of the throttle according to the bearing load, it is possible to improve bearing rigidity and achieve infinite rigidity.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1 (a) to 1 (d) are diagrams showing the operation principle of the present invention, and FIGS. 1 (a) and 1 (b) are schematic structural diagrams showing the operation principle of control of the bearing side position. c) is a diagram showing characteristics when the bearing is not controlled when a load is applied to the floating body,
FIG. 1D is a diagram showing characteristics when the bearing is controlled when a load is applied to the floating body.

In FIGS. 1A and 1B, reference numeral 11 denotes a hydrostatic gas bearing (hereinafter simply referred to as a bearing), and a bearing base 12 is provided above a linear stage 15. A required number of ejection holes 13 are formed on the surface of the bearing stand 12 (one is shown in FIGS. 1A and 1B), and a pressure gas 14 is ejected from an air supply device (not shown). Above it, a floating body 16 floating by the pressurized gas 14 is provided under a required load W. Linear stage 15
Is capable of linearly moving slightly in the up-down direction (coordinate Z direction). 1 (a) and 1 (b), only the pressure receiving body 17 is shown by omitting the other components of the floating body 16, and the pressure receiving body 17 is disposed to face the bearing base 12. ing. W is a load, and ΔW is a load further applied to the load W. Further, O is a portion that becomes a bearing surface on the upper surface of the bearing base 12, and h is a distance from the upper surface O of the bearing base 12 to the lower surface of the pressure receiving body 17.

In FIG. 1C, a point S0 is an operating point of the bearing 11, and a load ΔW is added to the load W of the pressure receiving body 17.
1A, in which the feedback control is not performed, the pressure receiving body 17 moves toward the bearing 11 by a distance Δh displaced from the point S0 to the point S1 as shown in FIG. The position indicated by the two-dot chain line is changed from the position indicated by the solid line in FIG. On the other hand, in the case of FIG. 1B in which the feedback control is performed, as shown in FIG. 1D, the upper surface O of the bearing stand 12 is displaced by a distance Δh as shown in FIG. , The point S0 moves to the point S2, but there is no change in the position of the pressure receiving body 17, and high rigidity is obtained.

FIG. 2 is a schematic sectional view of the hydrostatic gas bearing of the present invention. In the drawing, reference numeral 1 denotes a circular adjusting sleeve, and a minute gap between the adjusting sleeve and the cylindrical fixed sleeve 2 forms a slot-shaped air supply throttle. That is, the slot interval hs between the upper surface of the adjustment sleeve 1 and the fixed sleeve 2 and the adjustment sleeve 1
A gap hs1 between the upper cylindrical surface and the fixed sleeve 2 serves as a slot-shaped air supply throttle. The adjustment sleeve 1 is attached to a disk-shaped base 5 via the piezoelectric element 3. Reference numeral 6 denotes an O-ring for positioning the adjustment sleeve 1 and preventing leakage of air supply, reference numeral 7 denotes a floating body, and reference numeral 4 denotes a balance hole for keeping the lower surface of the adjustment sleeve 1 at ambient pressure. In addition, ro, rg, hs1, ls1, and rs each indicate the size of a main part.

FIG. 3 shows a control system diagram of the hydrostatic bearing of the present invention. When the gap Δh decreases due to an increase in the load applied to the floating body 7, the displacement meter 9 detects this and a voltage corresponding to the displacement is applied to the piezoelectric element 3 from the controller 8. Then, the piezoelectric element 3 contracts by an amount corresponding to Δh, the slot interval hs shown in FIG. 2 increases, the fluid resistance of the adjustment throttle decreases, and the length of the flow path of the gap hs1 also decreases. Decrease. This increases the pressure in the slot throttle static pressure gas bearing to increase the gap h. As a result, the gap h is kept constant and exhibits infinite rigidity.

FIG. 4 shows ro = 25 mm, rg = 15 m
m, hs1 = 10 μm, ls1 = 5 mm, rs = 30 m
m, design load W = 10kg, set clearance h = 10
μm, adjustment throttle gap for obtaining infinite rigidity at supply pressure Ps = 5 kg / cm ² , that is, slot interval h
The calculation results of s and the flow rate Q are shown.

Although the piezoelectric element 3 is used as a driving means of the adjusting sleeve 1, it may be a magnetostrictive element or the like.

In the above embodiment, the pressurized gas 14 is used. However, this may be a pressurized liquid. Therefore, the present invention is a hydrostatic bearing using a pressurized fluid.

[0016]

As is apparent from the above description, according to the present invention, the adjusting sleeve disposed in the hydrostatic gas bearing is controlled by the driving means in accordance with the displacement of the floating body. In addition, the bearing rigidity is significantly increased, and infinite bearing rigidity can be expected.

As a result, it is possible to minimize the change in displacement of the floating body with respect to the load fluctuation, to solve the problem of accuracy that could not be achieved conventionally due to insufficient rigidity of the bearing, and to use this gas for the bearing of industrial equipment. The use of bearings can contribute to improving the performance and reliability of equipment.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of operation of the present invention.
(B) is a schematic configuration diagram showing the principle of control operation of the bearing side position,
FIG. 1C shows the characteristics when the bearing is not controlled when a load is applied to the floating body, and FIG. 1D shows the characteristics when the bearing is controlled when a load is applied to the floating body. FIG.

FIG. 2 is a schematic sectional view showing a main part of the hydrostatic gas bearing according to the present invention.

FIG. 3 is a diagram showing a control system diagram of a hydrostatic gas bearing according to the present invention.

FIG. 4 is a diagram showing a relationship between a slot interval and a flow rate of an adjustment throttle for giving infinite rigidity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Adjusting sleeve 2 Fixed sleeve 3 Piezoelectric element 4 Balance hole 5 Base 6 O-ring 7 Floating body 8 Controller 9 Displacement gauge 11 Gas bearing 12 Bearing stand 13 Jet port 14 Pressure gas 15 Linear stage 16 Floating body 17 Pressure receiving body

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[Procedure amendment]

[Submission date] June 13, 2000 (2006.1.
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

In the hydrostatic bearing according to the present invention, the slot-shaped air-supply restrictor is provided with a slot space.
The fixed sleeve and the adjustment sleeve
Moving the adjusting sleeve in the vertical direction of the flow.
Fluid resistance is constituted by a movable member which can be adjusted in Rukoto, by moving the adjustment sleeve is intended to very high bearing stiffness by controlling the pressure and bearing flow throttle portion in accordance with the load fluctuation.

Claims (1)

[Claims] 1. A hydrostatic bearing in which a fluid is ejected through a slot-shaped air supply throttle to float a floating body and hold it in a non-contact manner, wherein the slot-shaped air supply throttle is constituted by a fixed sleeve and an adjustment sleeve. Driving means for moving the adjusting sleeve to adjust the slot interval with the fixed sleeve,
Detecting means for detecting displacement of the shaft due to the load on the floating body side, and control means for performing feedback control according to the detected displacement to drive the driving means to cancel the displacement of the floating body. A hydrostatic bearing.