GB837727A - Method and apparatus for forming lens blanks - Google Patents

Abstract

837,727. Multifocal lenses. PITTSBURGH PLATE GLASS CO. Sept. 2, 1958 [Oct 7, 1957], No. 28120/58. Addition to 739,341. Class 56. In making a multifocal lens blank wherein a minor segment 11 is placed, with its ground and polished surface uppermost, in a recess in a support such as 32, Fig. 6, 67, Fig. 10, the major segment is formed by depositing a mass of molten glass M closely adjacent, but spaced from, the edge of the minor segment and then progressively spreading the mass across the ground and polished surface. In one form of apparatus the spreading is effected by moving a barrel-shaped roller over the mass. In Fig. 6, a moulding member 37 is first swung about an axis 38 to distribute the molten glass over the minor segment, and the member 37 is then moved downwardly to press the blank to its final shape. The arm 43 carrying the member 37 itself forms part of a bracket swingable away from the support 32 so as to leave an unobstructed passage for depositing the glass M. In Fig. 10, a pusher member 72 is used to spread the molten glass. The minor segment may be on the convex side of the blank as in Fig. 6, or on the concave side as in Fig. 10.