Manufacturing method for glass molded products

Abstract

In a method for molding glass products having a fine structure as of an optical fiber holder with a high size precision, a mold used for the molding has the fine structure in a size such that a size difference occurring when the glass product is cooled down to a room temperature where at the end of molding with a pressure a size of the fine structure of the mold for glass product and a size of a fine structure of the glass product formed by transfer of the fine structure of the mold are the same as one another is so adjusted that a size of the fine structure of the completed glass product falls within a permissive size precision range. The mold may has a size satisfying, as a size of a fine structure at a room temperature, a formula [1+(.alpha.g-.alpha.m).times..DELTA.T+.alpha.g'.times..DELTA.T'].times.Sg, wherein Sg denotes a size of a fine structure of thc glass product at the room temperature; .alpha.g denotes a mean thermal expansion coefficient of the glass to be molded in a temperature range from the room temperature to the glass transition temperature of the glass to be molded; .alpha.m denotes a mean thermal expansion coefficient of the mold in a temperature range from the room temperature to the glass transition temperature of thc glass to be molded; .DELTA.T denotes a difference between the room temperature and the glass transition temperature of the glass to be molded; .DELTA.T' denotes a difference between a temperature at which the mold's pressure exerted to the glass product is released and the glass transition temperature, in a case where the mold's pressure exerted to the glass product is released at a temperature higher than the glass transition temperature after pressing the mold with a high pressure; and .alpha.g' is a thermal expansion coefficient of the glass to be molded at a mean temperature of summation of the glass sag temperature and the glass transition temperature.