U.S. Philips Corporation

Gerrit E Bartman

Hendricus F Smulders

Nicodemus Hattu

Willem J Lindhout

Sebastiaan F Trommelen

A method of manufacturing biconvex lens elements (21) comprising a biconvex glass lens (23) and a holder (1) consisting of two cylindrical rings (5,7), which are telescopically slidable with respect to each other and have different diameters so that an annular gap (9) is formed. A lens blank is heated together with the holder (1) in the telescopically extended position of the rings (5,7) to the processing temperature of the glass and is arranged between the heated dies (17, 19) of a mould, whereupon the dies (17, 19) are moved towards each other in a pressing stroke, the two rings (5,7) being telescoped into each other, the lens blank in the holder being moulded into a biconvex glass lens (23) and the excess quantity of glass being pressed from the hotter central part of the lens blank into the annular gap (9). The lens element (21) obtained after cooling is characterized by a biconvex glass lens (23), which is FIG. 7.

Method of manufacturing biconvex lens elements and element formed thereby

A method of and a device are provided for the high-precision manufacture of glass lenses where a roughly metered volume of softened glass is transferred in a product holder from a furnace to a position between two moulds, the moulds being subsequently moved towards one another and the excess glass being pressed from between the moulds. The moulds and the product holder are moved at such a mutual speed that both moulds simultaneously contact the article, and the movement of the moulds is terminated when they reach a given position with respect to one another.

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Eindhoven, Netherlands

Gerrit E Bartman