JPH0775826B2 - Flat polishing machine with processing pressure compensation mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a surface polishing apparatus with a working pressure correction mechanism capable of correcting the working pressure applied by an upper surface plate according to its wear.

[Prior Art] As shown in FIG. 4, upper and lower surface plates 1 and 2, a sun gear, and an internal gear 4 are provided and are held by a carrier 5 driven by both gears 3 and 4 in a planetary gear shape. A flat surface polishing apparatus is known in which the work 6 is polished by the upper and lower surface plates 1 and 2.

In such a flat surface polishing apparatus, the upper surface plate 1 is supported by a cylinder 7 suspended in a machine frame (not shown) so as to be lifted and lowered.
At the time of processing the work 6, the upper surface plate 1 is pressed against the work 6 by the fluid pressure such as air supplied to the cylinder 7. That is, the fluid pressure is supplied to the rod chamber 7b of the cylinder 7, and an acting force slightly larger than the weight W of the upper surface plate 1 is always applied upward to the piston 7c. By supplying / discharging, the upper surface plate 1 is moved up and down, and the working pressure is applied.

However, since the surface plate 1 gradually wears due to processing and its weight changes, the processing pressure also gradually changes, and the processing accuracy is reduced. Therefore, in order to maintain the processing accuracy, it is necessary to correct the processing pressure according to the wear of the surface plate. In particular, in recent years, extremely high precision has been required for polishing semiconductor wafers and the like, and the correction of the processing pressure is extremely important from the viewpoint of meeting the demand.

[Problems to be Solved by the Invention] An object of the present invention is to provide a surface polishing apparatus capable of correcting a processing pressure according to wear of an upper surface plate.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the surface polishing apparatus of the present invention, the upper platen is supported by a cylinder so as to be vertically movable, and the upper platen is formed by the fluid pressure supplied to the cylinder. The flattening device for setting the working pressure is additionally provided with a working pressure correction mechanism for keeping the working pressure at the set pressure by correcting the working pressure for the weight change due to the wear of the upper surface plate. A pressure correction mechanism, a sensor that measures the weight of the upper surface plate,
A control circuit that compares a measured value by the sensor with a reference value input in advance and outputs a control signal corresponding to the difference between them, and a fluid pressure that is driven by the control signal from the control circuit and is supplied to the cylinder. And a pressure control valve for controlling.

[Operation] When the weight of the upper surface plate is measured by the sensor, the measured value is input to the control circuit and compared with the reference value input in advance here. Then, a control signal corresponding to the difference between them is output to the pressure control valve to control the fluid pressure supplied to the cylinder, and the working pressure is corrected by the wear of the upper surface plate.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

The flat-surface polishing apparatus shown in FIG. 1 has basically the same structure as the known one shown in FIG. That is, the upper and lower surface plates 11 and 12, the sun gear 13, and the internal gear 14, both gears 13,
A work 16 held by a carrier 15 driven in a planetary gear shape at 14 is configured to be polished by upper and lower surface plates 11 and 12.

A cylinder 17 that supports the upper surface plate 11 so as to be able to move up and down is suspended from a machine frame (not shown) or a rod of another cylinder attached to the machine frame, and has a configuration specifically shown in FIG. have. That is, the cylinder 17 has the first and second
Two pistons 18 and 19 and a piston rod 20 connected to the upper surface plate 11, the first piston 18 is fixed to the piston rod 20, and the second piston 19 is fixed within a certain range. It is fitted so as to be movable in the axial direction.
A sensor 21 such as a strain gauge for measuring the weight of the upper surface plate 11 is mounted on the surface of the second piston 19 facing the first piston 18. The sensor 21 is in contact with the first piston 18 in a state where the second piston 19 moves toward the first piston 18 side due to fluid pressure, and measures the weight of the upper surface plate 11 via the first piston 18. At this time, in order to prevent the impact load or the like from the upper surface plate 11 from acting on the sensor 21, it is necessary to prevent the second piston 19 from approaching the first piston 18 side more than the distance required for measurement. It is regulated by.

A pressure control valve 25 for controlling fluid pressure according to an electric input signal is provided in the flow path 24 of the cylinder 17 on the side of the head chamber 17a, and a control circuit is provided between the pressure control valve 25 and the sensor 21.
26 is connected.

The control circuit 26 compares the value measured by the sensor 21 with a reference value of weight inputted in advance, and controls the pressure control valve 25 according to the difference between them. For example, as shown in FIG. Can be configured. That is, this control circuit 26
Is a sample and hold circuit that holds the measurement signal from the sensor 21 for a certain period of time, an A / D converter that converts the held analog signal into a digital signal, and compares the converted signal with a pre-input reference value. Computation is performed, and an arithmetic circuit for obtaining the difference between the arithmetic circuit and the D / A converter that converts the signal from the arithmetic circuit to an analog signal and outputs the analog signal is output. Pressure control valve
The fluid pressure input to the head chamber 17a of the cylinder 17 is controlled by the pressure control valve 25. Further, a display device such as a cathode ray tube or a neon tube is connected to the arithmetic circuit so that the measured weight and wear amount of the surface plate are displayed.

In the flat surface polishing apparatus having the above configuration, the work 16 is processed by the upper and lower surface plates 11 and 12 in the same manner as a known polishing apparatus. At this time, the fluid pressures P ₁ and P ₂ are supplied to the head chamber 17a and the rod chamber 17b of the cylinder 17, respectively. Therefore, the upper platen 11 is F = S ₁ P ₁ + W−S ₂ P ₂ (1) S ₁ : Pressure receiving area of the first piston S ₂ : Pressure receiving area of the second piston W: The pressure of the upper platen is pressed against the work 16.

When the processing is completed, the fluid pressure in the head chamber 17a is discharged, and the upper surface plate 11 is raised by the acting force of S ₂ P ₂ acting on the second piston 19. This acting force S ₂ P ₂ is set so as to be slightly larger than the weight W of the upper surface plate 11, so that the upper surface plate 11 rises at a slow speed. The weight W of the upper surface plate 11 is measured.

The measurement signal from the sensor 21 is input to the control circuit 26 and compared with a reference value that is input in advance such as by performing predetermined signal processing, and the wear amount of the upper surface plate 11 is obtained as the difference between them. To be

Then, the control circuit 26 outputs a control signal corresponding to the difference to the pressure control valve 25, and the fluid pressure supplied to the head chamber 17a of the cylinder 17 at the time of the next processing is increased. Therefore, in the above formula (1), the weight W of the upper surface plate 11
There was increased and decreased correspondingly fluid pressure P _1, the processing pressure F will be kept constant.

On the other hand, the measured weight and wear amount of the surface plate are displayed on the display.

As described above, according to the present invention, the weight of the upper platen is measured by the sensor, and the fluid pressure supplied to the cylinder is adjusted by the amount of wear of the upper platen. Regardless of this, the processing pressure can always be kept constant, and the processing accuracy of the work can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of an embodiment of the present invention, FIG. 2 is a partially enlarged view thereof, FIG. 3 is a block diagram showing a configuration example of a control circuit, and FIG. It is a partial block diagram which shows. 11 …… Upper surface plate, 17 …… Cylinder, 21 …… Sensor, 25 …… Pressure control valve, 26 …… Control circuit.

Claims (1)

[Claims] 1. A flat surface polishing apparatus in which an upper surface plate is supported by a cylinder so as to be able to move up and down, and a processing pressure by the upper surface plate is set by a fluid pressure supplied to the cylinder. A processing pressure correction mechanism is attached to correct the processing pressure with respect to the amount of change so as to maintain the processing pressure at a set pressure. The processing pressure correction mechanism includes a sensor for measuring the weight of the upper surface plate and a measurement by the sensor. A control circuit that compares the value with a reference value that is input in advance and outputs a control signal corresponding to the difference between them, and a pressure that is driven by the control signal from the control circuit and that controls the fluid pressure supplied to the cylinder. A flat polishing device with a processing pressure correction mechanism, which comprises a control valve.