Patent ID: 6790388
Filing Date: 2004-09-14
Classification: B29C,B29D,B29L,Y10S

Abstract:
A method of injection molding a lens out of thermoplastic synthetic material by means of a mold containing a mold recess, said material being previously melted to a molding temperature higher than or equal to its vitreous transition temperature, the method comprising, for each lens molding cycle, the following steps:raising the wall of the mold cavity to a heating temperature higher than or equal to the molding temperature of said material; filling the molding cavity with said material; at the end of filling, increasing the pressure of said material introduced in this way into the molding cavity up to a compacting pressure; and bringing the wall of the molding cavity to a cooling temperature to cool said molded material down to an unmolding temperature below its molding temperature, said cooling temperature being lower than said unmolding temperature; wherein the filling of the molding cavity with said material begins before the heating temperature has been reached, and wherein, once both the compacting pressure of said material and the heating temperature of said molding cavity have been reached, they are both maintained for a given length of time.