| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of press-forming capable of properly conducting press-forming of a quarts glass substrate. SOLUTION: This method of press-forming to form V-shape trenches on the surface 22a of a quarts glass substrate material 22 comprises a heating step of heating the quarts substrate material 22 in a heating oven 20 to a temperature above 1400 deg.C in the transformational region enabling press-forming, a pressing step of forming V-shape trenches by pressing the quarts glass substrate material 22 with molds 4 and 5 while keeping the temperature of the softened quarts glass substrate material in the range of the transformational region, and a releasing step of releasing the quarts glass substrate material with V- shape trenches from molds 4 and 5 after pressing, where in the heating step the heating time to elevate the temperature of the quarts glass substrate material from ambient temperature to the press-forming temperature is 10 minutes or longer, pressing time in the pressing step is one minute or longer, and the temperature at releasing in the releasing step is 700 deg.C or higher.
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