Method for manufacturing glass plate including processing for chamfering edge surface

A method for manufacturing a glass plate, the method comprising:

• chamfering processing for chamfering an inner circumferential edge surface and an outer circumferential edge surface of a glass blank, the glass blank having an annular shape with a circular hole at a central portion of the glass blank, the glass blank including a pair of main surfaces, the inner circumferential edge surface forming a contour of the circular hole, and the outer circumferential edge surface, the chamfering processing including
• forming a chamfered surface by irradiating, with a laser beam, the outer circumferential edge surface of the glass blank, and forming a chamfered surface by irradiating, with the laser beam, the inner circumferential edge surface of the glass blank, in an order of the irradiating of the outer circumferential edge surface and the irradiating of the inner circumferential edge surface, and
• heating the glass blank before irradiation with the laser beam to the outer circumferential edge surface of the glass blank,
• the chamfering processing being performed such that a retardation value at an inner end portion of one of the main surfaces, which is located on an inner circumferential edge surface side of the one of the main surfaces, is larger than a retardation value at an outer end portion of the one of the main surfaces, which is located on an outer circumferential edge surface side of the one of the main surfaces,
• 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, and
• a temperature of the glass blank at which the inner circumferential edge surface is irradiated with the laser beam is lower than a temperature of the glass blank at which the outer circumferential edge surface is irradiated with the laser beam.

A method for manufacturing a glass plate, the method comprising:

• chamfering processing for chamfering an inner circumferential edge surface and an outer circumferential edge surface of a glass blank, the glass blank having an annular shape with a circular hole at a central portion of the glass blank, the glass blank including a pair of main surfaces, the inner circumferential edge surface forming a contour of the circular hole, and the outer circumferential edge surface, the chamfering processing including
• forming a chamfered surface by irradiating, with a laser beam, the inner circumferential edge surface of the glass blank,
• forming a chamfered surface by irradiating, with the laser beam, the outer circumferential edge surface of the glass blank, and
• heating the glass blank before irradiation with the laser beam to the inner circumferential edge surface and the outer circumferential edge surface of the glass blank,
• the chamfering processing being performed such that a retardation value at an inner end portion of one of the main surfaces, which is located on an inner circumferential edge surface side of the one of the main surfaces, is larger than a retardation value at an outer end portion of the one of the main surfaces, which is located on an outer circumferential edge surface side of the one of the main surfaces,
• 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, and
• a temperature of the glass blank at which the inner circumferential edge surface is irradiated with the laser beam is lower than a temperature of the glass blank at which the outer circumferential edge surface is irradiated with the laser beam.