Hydrostatic Bearing Pressure Control for Double-Disc Grinding
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Solution Overview
Problem
Conventional double-disc grinding methods fail to maintain stable, high precision in nanotopography due to variations in raw material workpieces and grinding wheels, leading to degradation of surface irregularities.
Innovation Solution
A double-disc grinding apparatus with a rotatable ring holder supported by a hydrostatic bearing that allows independent control of fluid supply pressures from the direction of the rotational axis and perpendicular to it, enabling precise control of support rigidities to maintain consistent nanotopography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hydrostatic bearing is used to support the ring holder, then the ring holder can be supported without contact, but the nanotopography degrades and highly precise nanotopography cannot be obtained stably
Solution Approach 1:
The hydrostatic bearing is divided into two independent subsystems: one for supplying fluid in the axial direction (parallel to rotational axis) and another for supplying fluid in the radial direction (perpendicular to rotational axis). Each subsystem has independent pressure control, allowing separate optimization of support stability and nanotopography precision without mutual interference.
Solution Approach 2:
The invention changes the pressure parameter independently for each fluid supply direction. By controlling the supply pressure of axial-direction fluid and radial-direction fluid separately, the system can optimize both the stability of ring holder support and the precision of nanotopography, resolving the contradiction between reliable support and manufacturing precision.
2Reliability
If fluid supply pressure is increased to improve support stability, then the ring holder is more stably supported, but the nanotopography precision deteriorates due to increased local pressure differentials
Solution Approach 1:
The fluid supply system is segmented into axial and radial components with independent pressure control. This allows the axial supply pressure to be optimized for support stability while the radial supply pressure is optimized for nanotopography precision, eliminating the need to compromise either parameter.
Solution Approach 2:
By independently changing the pressure parameters for axial and radial fluid supply, the system can achieve high support stability through optimized axial pressure while maintaining nanotopography precision through optimized radial pressure, resolving the trade-off between these two requirements.
3Device complexity
If the same fluid supply pressure is used in all directions, then the system is simpler to control, but the nanotopography precision cannot be maintained when workpiece lots or grinding wheels are changed
Solution Approach 1:
The control system is segmented into two independent pressure control units: one for axial-direction fluid supply and another for radial-direction fluid supply. This segmentation enables flexible adjustment of each direction's pressure to adapt to different workpiece lots and grinding wheels, maintaining precision without excessive complexity.
Solution Approach 2:
The system transitions from static uniform pressure control to dynamic independent pressure control. Each fluid supply direction can dynamically adjust its pressure based on specific requirements, allowing the system to adapt to variations in workpiece lots and grinding wheels while maintaining nanotopography precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus achieves stable and highly precise nanotopography by independently controlling support rigidities, reducing local pressure differentials and maintaining high precision even when workpiece lots or grinding wheels are changed.
Implementation Method 1
a hydrostatic bearing for supporting the ring holder without contact from both of a direction of a rotational axis of the ring holder and a direction perpendicular to the rotational axis by hydrostatic pressure of fluid supplied from both the directions
Data Source
AI summary
The invention is directed to a double-disc grinding apparatus including: a rotatable ring holder configured to support a sheet workpiece along a circumferential direction from an outer circumference side of the workpiece; a pair of grinding wheels for grinding surfaces of the workpiece supported by the ring holder; and a hydrostatic bearing for supporting the ring holder without contact from both of a direction of a rotational axis of the ring holder and a direction perpendicular to the rotational axis by hydrostatic pressure of fluid supplied from both directions, wherein supply pressures at which the fluid is supplied from the direction of the rotational axis and from the direction perpendicular to the rotational axis can be independently controlled. The invention provides a double-disc grinding apparatus and a workpiece double-disc grinding method that can improve variation in nanotopography depending on the lot of workpieces or grinding wheels to obtain nanotopography stably.