DIE FOR FORMING GLASS SUBSTRATE FOR DISK, METHOD FOR MANUFACTURING GLASS SUBSTRATE FOR DISK, APPARATUS FOR MANUFACTURING GLASS SUBSTRATE FOR DISK AND GLASS SUBSTRATE FOR DISK

摘要

PROBLEM TO BE SOLVED: To eliminate the fissures of glass substrates in die parting thereof by forming the glass substrates in such a manner that a glass material can be easily parted from die surfaces during cooling. SOLUTION: The method has a preheating process step of preheating the glass material, a pressing process step of press forming the glass material and a cooling process step of cooling the glass material. The pressing process step applies a die lubricant on the press forming surface of the die in press forming. As a result, in parting the glass material from the die after the press forming, their tight contact force is reduced by the die lubricant component remaining at the boundary between the die and the glass material, by which the parting is made easy and the occurrence of the fissures of the glass is effectively prevented.