Raised-Center Chuck Grinding for Warped Plate Workpieces
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Solution Overview
Problem
The existing methods for grinding warped plate-formed workpieces, such as adhering tape to create a closed space, are burdensome and lower working efficiency.
Innovation Solution
A method involving a first holding process to suction and hold the workpiece against a raised-center chuck table, a reaction-force reducing grinding process, a second holding process to suction and hold the workpiece parallel to the grindstone, and a finish-grinding process to achieve even thickness without forming a gap, using a grinding apparatus with multiple chuck tables and suction paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tape is adhered to the workpiece to form a closed space for holding, then the workpiece can be held on the chuck table, but the working efficiency is lowered due to the burdensome process
Solution Approach 1:
The patent uses suction force generated by a vacuum mechanism to hold the workpiece directly on the chuck table without requiring tape adherence. The suction force acts through the thickness of the workpiece to secure it firmly in place, eliminating the need for manual tape application while maintaining reliable holding stability.
Solution Approach 2:
The patent extracts and eliminates the tape adherence step from the holding process. By using direct suction holding, the complex process of adhering tape and forming closed spaces is removed, leaving only the essential function of holding the workpiece, thereby improving working efficiency.
2Shape
If the center part of the workpiece is ground to flatten the warpage, then the workpiece shape is improved, but the reaction force against flattening force increases
Solution Approach 1:
The patent applies suction force not only at the outer circumference but also at the center part of the workpiece. This partial action at the center helps to suppress the reaction force generated during flattening grinding by providing additional holding force where the warpage is most pronounced, allowing for better shape control with reduced overall reaction force.
Solution Approach 2:
The patent creates different holding conditions at different locations of the workpiece by applying suction force both at the outer circumference and at the center. This local differentiation in holding force distribution allows the center part to be held more firmly during flattening grinding, reducing the reaction force against the flattening force while improving the overall workpiece flatness.
3Device complexity
If the workpiece is held with a conventional flat chuck table, then the holding is simple, but the warpage causes grinding precision to deteriorate
Solution Approach 1:
The patent uses a chuck table with a raised center portion that can be adjusted in height relative to the outer circumference. This dynamic structure allows the chuck table to adapt to the warped shape of the workpiece, providing proper support and maintaining grinding precision without requiring a completely complex specialized fixture.
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
Improves working efficiency by reducing reaction forces and eliminating the need for tape adherence, allowing for efficient grinding of warped plate-formed workpieces with raised centers.
Implementation Method 1
a suction path connecting the holder surface and a suction source; and a pressure adjuster device arranged in the suction path and configured to adjust a negative pressure value of the holder surface
Data Source
AI summary
A method for grinding a plate-formed workpiece having a raised center with a grindstone is provided. The method includes a first holding process including suctioning and holding the plate-formed workpiece against a holder surface of a first chuck table, which is in a shape where a center is raised with respect to an outer circumference thereof; a reaction-force reducing grinding process including grinding a central part of the plate-formed workpiece with the grindstone to reduce a reaction force against a flattening force to be applied to the plate-formed workpiece; a second holding process including suctioning and holding the plate-formed workpiece against a holder surface of a second chuck table, which spreads in parallel to a lower surface of the grindstone; and a finish-grinding process including grinding to finish the plate-formed workpiece with the grindstone.