Multiple optical curve molds formed in a solid piece of polymer
US5938988A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 19, 1996 |
| Grant date | Aug 17, 1999 |
| Priority date | — |
| Expiry date | Aug 19, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S425/808
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An injection molding process for molding an assembly of a frontcurve molds in a plurality of unitary solid piece of polymer in which plurality of frontcurve molds are arranged symmetrically around a single center polymer injection gate. In this arrangement the molten polymer flows radially outwardly therefrom uniformly in all directions to the four frontcurves to form one common molded piece of polymer. In a compression injection molding process, the pressure on the molten polymer is maintained relatively constant, and the mold is mechanically collapsed during the molding operation. The present invention molds an assembly of frontcurve molds in a manner in which there is a significant reduction of residual stress locked into the resultant assembly of frontcurve molds. This results in a significant reduction in warpage and shrinkage of each frontcurve mold, which is not optically stressed, and results in a subsequent casting of an ophthalmic lens which is not optically stressed. Moreover, the assembly of frontcurve molds can function as its own support pallet for product placement and alignment purposes during subsequent production operations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.