Laser End-Face Processing for Round Disk Glass Substrates
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Solution Overview
Problem
Conventional laser-based end face processing for glass substrates often results in deteriorated roundness of the inner and outer circumferential end faces, leading to potential air flow disturbances during high-speed rotation, which can cause fluttering in magnetic-disk glass substrates.
Innovation Solution
Perform laser beam irradiation along a distance longer than one lap of the outer and inner circumferential end faces, with an overlapping distance greater than or equal to the spot diameter and less than twice the spot diameter, to ensure a roundness of 15 μm or less and a recess depth of 15 μm or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser beam irradiation is performed along a distance of one lap of the circumferential end face, then the end face is smoothed and chamfered surfaces are formed, but the roundness of the end face deteriorates (increases)
Solution Approach 1:
The patent changes the irradiation distance parameter from one lap to more than one lap (specifically 1.05 to 1.5 times one lap), which fundamentally alters the heating pattern and prevents roundness deterioration while maintaining smoothing and chamfering effects
Solution Approach 2:
The patent applies excessive action by irradiating beyond one complete lap of the circumferential end face. This partial overlap of irradiation paths ensures uniform heating and prevents the formation of non-uniform protrusions that would deteriorate roundness, while still achieving the desired smoothing and chamfering
2Object-affected harmful factors
If the end face roundness deteriorates after laser irradiation, then air flow disturbance occurs during high-speed rotation, but the smoothing effect is achieved
Solution Approach 1:
By changing the irradiation distance to more than one lap, the patent prevents roundness deterioration at the source, thereby eliminating the root cause of air flow disturbance and fluttering during high-speed rotation of magnetic disks
Solution Approach 2:
The patent takes preliminary anti-action by preventing roundness deterioration through optimized irradiation distance before the magnetic disk is assembled and put into operation. This prevents future air flow disturbances and fluttering issues that would occur during high-speed rotation
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 method maintains the roundness of the end faces, reducing the risk of air flow disturbances and fluttering, while ensuring smooth chamfered surfaces for accurate magnetic disk integration and performance.
Implementation Method 1
the outer circumferential end face of the disk-shaped glass blank is irradiated with a laser beam L
Implementation Method 2
the inner and outer circumferential end faces of the annular glass blank are irradiated with a laser beam to heat them to a temperature higher than or equal to the softening point of the glass, thereby melting the inner and outer circumferential end faces
Data Source
AI summary
A disk-shaped glass substrate manufacturing method for manufacturing a disk-shaped glass substrate includes preparing a disk-shaped glass blank having a main surface and an outer circumferential end face, and performing irradiation with a laser beam along a distance longer than one lap of the outer circumferential end face of the disk-shaped glass blank.