| 摘要 |
A high precision optical element(21) such as glass lenses is hot pressed in a mould cavity formed by a transportable ring member(30) and a pair of upper and lower contour rams(11, 12). The transportable ring member comprises an upper ring(1) having a stepped hole in its lower portion and a lower ring(2) having a stepped hole in its upper portion. The upper portion of the lower ring is inserted into the inside stepped hole of the upper ring whose coefficient of thermal expansion is larger than that of the lower ring. The two rings are tightly fitted to each other when the transportable ring member containing a glass preform is pre-heated together. An annular ring groove which is formed by the stepped surfaces of the lower and upper rings, is useful in making a mould fin to prevent the pressed lens from sticking to the upper ram.
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