Method for manufacturing glass plate, method for chamfering glass plate, and method for manufacturing magnetic disk

A method for chamfering a glass plate in which a chamfered surface is formed on an edge surface of a glass plate having a disk shape through irradiation with a laser beam,

• wherein the edge surface of the glass plate before the chamfered surface is formed has at least a surface that is perpendicular to a main surface in a central portion of the glass plate in a thickness direction of the glass plate, and
• the method comprises:
• chamfering an edge portion of the edge surface of the glass plate into a round shape by
• obtaining in advance a relationship between Pd×Th, a moving speed V, and a shape of the edge surface to be obtained by the chamfering, by examining shapes of edge surfaces of glass plates that are obtained by irradiating the edge surfaces with the laser beam under a plurality of conditions, respectively, the plurality of conditions being conditions in which the moving speed V, a power density Pd of the laser beam, and a thickness for the glass plates are each changed, wherein a thickness of the glass plate is Th (mm), the power density of the laser beam is Pd (W/mm2), and the moving speed at which the laser beam moves relative to the edge surface along the edge surface is V,
• controlling the Pd×Th and the moving speed V based on the obtained relationship such that the chamfered surface is formed so as to have a round shape, and
• softening and/or melting the edge portion by irradiating the edge surface of the glass plate with the laser beam in accordance with the Pd×Th and the moving speed V that have been controlled.

A method for chamfering a glass plate in which a chamfered surface is formed on an edge surface of a glass plate having a disk shape through irradiation with a laser beam,

• wherein the edge surface of the glass plate before the chamfered surface is formed has at least a surface that is perpendicular to a main surface in a central portion of the glass plate in a thickness direction of the glass plate, and
• the method comprises:
• controlling Pd×Th and a moving speed V
• such that an edge portion of the edge surface of the glass plate is chamfered into a round shape by softening and/or melting the edge portion of the edge surface of the glass plate by irradiating the edge surface of the glass plate with the laser beam, wherein a thickness of the glass plate is Th (mm) that is 0.7 mm or less, a power density of the laser beam is Pd (W/mm2), and the moving speed at which the laser beam moves relative to the edge surface along the edge surface is V, and
• such that the moving speed is 20 (mm/s) or more, and the Pd×Th is 14.3 (W/mm) or more;
• and
• chamfering the edge portion of the edge surface of the glass plate in accordance with the Pd×Th and the moving speed V that have been controlled, and
• the controlling of the Pd×Th and the moving speed V being performed by adjusting a value of the Pd×Th and a value of the moving speed such that y is in a range of 11.2×x−4.7 or lower and 3.8×x−5.6 or higher, wherein the Pd×Th is x, and the moving speed V is y (mm/s).