Method for manufacturing glass plate, method for manufacturing glass substrate for magnetic disk, method for manufacturing magnetic disk, and annular glass plate
AssigneeHoya Corporation
InventorShuhei AZUMA
Life of this patent
Estimating the term…
Abstract
In a method for manufacturing a glass plate that includes chamfering processing for chamfering an edge surface of a glass plate, the chamfering processing includes a step of forming a chamfered surface by irradiating the edge surface of the glass plate with a laser beam, and a step of heating the glass plate before the chamfered surface is formed. When a temperature of the glass blank at which the glass blank is heated is Tp [° C.], a glass transition point of the glass blank is Tg [° C.], and an average coefficient of linear thermal expansion of the glass blank is α [1/° C.], (Tg−Tp)≤−5.67×107·α+840 is satisfied.
Claims11
A method for manufacturing a glass plate, comprising processing for chamfering an edge surface,
- wherein the chamfering processing includes:
- a step of forming a chamfered surface by irradiating, with a laser beam, the edge surface of a glass blank before being subjected to the chamfering processing;
- and
- a step of heating the glass blank before irradiation with the laser beam,
- wherein, when a temperature of the glass blank at which the glass blank is heated is Tp [° C.], a glass transition point of the glass blank is Tg [° C.], and an average coefficient of linear thermal expansion of the glass blank is α [1/° C.], (Tg−Tp)≤−5.67×107·α+840 is satisfied.
An annular glass plate having a circular hole at a central portion of the glass plate, the annular glass plate comprising:
- a main surface;
- an inner circumferential edge surface forming a contour of the circular hole;
- and
- an outer circumferential edge surface,
- wherein the glass plate has chamfered surfaces on the inner circumferential edge surface and the outer circumferential edge surface, and
- the maximum residual stress at an end portion of the main surface in a vicinity of the inner circumferential edge surface is larger than the maximum residual stress at an end portion of the main surface in a vicinity of the outer circumferential edge surface.
Dependencies are inferred from the claim text.