JPS58165959A - Fine displacement/angle setting device - Google Patents

Abstract

PURPOSE:To obtain a fine displacement/angle setting device capable of setting a fine displacement or angle with high precision by controlling the feed pressure of a working fluid to stationary pressure pads provided above and below a pair of stationary pressure bearings so as to control the displacement of a table. CONSTITUTION:A table 1 is supported rotatably to the right or left by stationary pressure pads 4-9 provided on a pivot member 3 on a fixed base mount 2 through bearing clearances. Servo valves 10, 11 are controlled so as to control the pressure of the working fluid to lower stationary pressure pads 4, 6 and upper stationary pressure pads 5, 7, thus the table 1 can be slightly moved up and down or rotated through fixed orifices 14-17. In addition, the stationary pressure pads 8, 9 fixed orifices 12, 13 to hold the table 1 at a fixed position. When command signals Hc1, Hc2 from a controller 20 are introduced into servo valves 10, 11 through servo amplifiers 18, 19 and the pressure difference is applied to the upper and lower stationary pads 5, 4 and 7, 6 respectively, the table 1 is slightly displaced or rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that applies minute displacement or rotation to an imaginary member.

In general, when trying to make a control target member, such as the table of a surface grinder, move or rotate by a minute amount, or change displacement and rotation, a convenient device is used. It is desirable to have high rigidity and high resolution. No conventional device satisfies all of these conditions.

The present invention enables highly accurate displacement, rotation, or displacement of the controlled member by controlling the pressure supplied to two or more opposing static pressure pads to a differential pressure commanded by a servo valve. The overall purpose of this invention is to provide an inexpensive device that has low backlash, high static and dynamic rigidity, and rotation.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a device commonly used as a workpiece mounting jig for a surface grinder, and the jig part is shown in cross section. The table 1, which is a member to be controlled, has a bearing clearance with respect to the pivot member 3 by six static pressure pads 4, 5, 6, 7, 8, and 9 provided on the pivot member 3 fixed to the base surface plate 2. It is supported by a hydrostatic bearing structure so that it can rotate from side to side. This table 1 controls the pressure of the working fluid to the lower static pressure pads 4 and 6 and the upper static pressure pads 5 and 7 by controlling the servo cells 10 and 11', and controls the pressure of the working fluid to the lower static pressure pads 4 and 6 and the upper static pressure pads 5 and 7. , it is possible to move the table 1 microscopically up and down c4wJ or rotate it. In addition, the static pressure pads 8 and 9 placed on the left and right sides receive a constant supply pressure P,,P, through fixed throttles of 12° and 13-metal gold, thereby holding the table 1 at a constant position in the left-right direction. It consists of Command signal Hc1. output from controller 20. Hc2
are connected to servos 10 and 1 via servo amplifiers 18 and 19.
I am guided by 1. Here, the servo valves 10 and 11 control the table 1 by applying differential pressure to the opposing upper and lower static pressure pads 5, 4 and 7, 6 according to a control signal, and are proportional to the command value. It produces a differential pressure.

Next, the operation will be explained. Displacement command signal H6I.

When Ho2 is applied to the servo amplifier 18.19, the command signal H6, a control signal proportional to Ho2 11 s ■2
servo valve 10.11. This servo valve 10.11 distributes the working fluid supply pressure P# Psutk so that the differential pressure between the upper and lower static pressure pads 5, 4 and 7, 6 is proportional to the command signal H6I r H (t. The pressure is applied to fixed throttles 16, 14 and 17.
1!1 and reaches the upper and lower static pressure pads 5, 4 and 7.6. The bearing clearance 1 changes according to the pressure difference between the upper and lower static pressure pads 5, 4 and 7°6, and the upper and lower static pressure pads 5, 4 that face each other change.
The bearing clearance becomes stable when the pressures 7 and 6 are balanced.

When moving table 1 upward, command signal k
If HC1'' is set to Hot and the supply pressure to the lower static pressure pads 4 and 6 is made higher than the supply pressure to the upper static pressure pads 5 and 7, the bearing clearance at the lower static pressure pads 4 and 6 will be large. Since the bearing clearance between the upper static pressure pads 5 and 7 becomes smaller, the table 1 is displaced upward.When rotating the table 1, if the command signal fHctζ'C2 is used, the right side of the table 1 is moved upward. Since the left side is displaced downward by the same amount, the table 1 rotates by a small angle counterclockwise about its axis O. In general, the displacement and rotation of table 1
1 is the displacement tH9 rotation angle of the center of the table 1 as θ.

Set the upper static pressure pads 5 and 7 to L and nH unit.
(Hc++HC2)/2, sin θ”
” (Hc 1 HC2)/L. Here, if HCl-H,, is sufficiently smaller than LK, it can be approximated as white (Ho, -H6,)/L. Since L can be constant, H81-HC2 If controlled, introposition and displacement can be controlled.

If the displacement of table 1 is small enough to compensate for the bearing clearance,
The command value and displacement are proportional, but as the displacement increases, it becomes proportional]
I won't. Therefore, the relationship between the 11th order of magnitude and the displacement or angle is measured in advance and stored in the error controller 20, and the command value is adjusted so that the error becomes zero. Also, calculate all the changes in the top surface of table 1 due to the inclination,
It is also possible to control the height of the point on the table 1 to be constant.

Figure 2 shows experimental data showing the response of the table, with one step of 0.06. IJ? ? ! It represents the displacement of the table when the command is given. As is clear from the figure, minute displacement has been achieved.

Note that the working fluid can be not only a liquid such as oil but also a gas such as air. Further, in the above embodiment, the arrangement of the static pressure pads of a pair of hydrostatic pressure bearing structures was shown, but by arranging two or more pairs of this structure in parallel, the rigidity against moment loads can be increased. Furthermore, by arranging the configuration of the above embodiment in a direction other than the plane of FIG. 1, for example, in a direction perpendicular to the plane of FIG. 1, it is also possible to control the movement of the table in a combination of two orthogonal directions. .

As explained above, the present invention controls the displacement of a controlled member by controlling the supply pressure of working fluid to the static pressure pads provided above and below each of at least a pair of facing static pressure bearings. It is characterized by the ability to set minute displacements and angles, and can simultaneously set displacement and rotation to a high degree, making it extremely useful in many fields such as machine tools such as surface grinders and precision measuring instruments. It is a device with

[Brief explanation of the drawing]

Figure 1 is a block diagram of an embodiment of the present invention, and Figure 2 is a graph of experimental values for the apparatus shown in Figure 1. DESCRIPTION OF SYMBOLS 1... Table, 2... Basic surface plate, 3... Pivotal support member, 4, 6... Lower static pressure pad, 5, 7... Upper static pressure pad, 10.11...・Servo square, 18.19... Servo amplifier, 20... Controller.

Claims (1)

[Claims] a member to be controlled; a pivot member rotatably supporting the member to be controlled by a pair of hydrostatic bearings; a pair of static pressure regulators, a pair of controllers that issue command signals, an amplifier that fully amplifies the command signals, and adjusts the supply pressure of the working fluid above and below in response to the control signal from the amplifier. A minute displacement angle setting device consisting of a servo valve that distributes static pressure to the ground.