Patent ID: 8973404
Filing Date: 2015-03-10
Classification: C03B,C03C,G11B

Abstract:
1. A manufacturing method of a glass substrate for a magnetic disk including a pair of principal surfaces, the method comprising: forming a glass blank by performing press forming to molten glass or softened glass with planar press forming inner surfaces of a pair of dies in such a way that the molten glass or the softened glass is sandwiched between the inner surfaces from both sides in a horizontal direction while maintaining a temperature difference between the inner surfaces of the pair of dies at or below 5 degrees Celsius to equalize a temperature condition around the pair of principal surfaces of the glass blank and creating a heat flow in the inner surfaces of the pair of dies during the press forming to form the pair of principal surfaces of the glass blank with concave shapes such that a section thickness of the glass blank decreases from the outer circumference of the glass blank toward the center of the glass blank; and polishing the glass blank.