| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus for press forming capable of improving dimensional precision of an optical element by suppressing warpage of a master block, and to provide a method for press forming. SOLUTION: The press forming apparatus 100 is provided with a pair of upper and lower master blocks 102 and 104, where each master block 102 and 104 has four forming faces arranged in a row, and each master block 102 and 104 is constituted so as to satisfy a relationship: L×α×ΔT/t<0.0008 (wherein L is the length, t is the thickness,αis a coefficient of thermal expansion, andΔT is a temperature difference generated between both ends in the thickness direction at the induction heating), thereby warpage of each master block 102 and 104 is suppressed and dimensional accuracy of the optical element is improved.
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