TITLE:
3D Modelling of Thermal Replication for Designing Progressive Glass Moulds
AUTHORS:
Dominique Lochegnies, Philippe Moreau, Fabienne Hanriot, Patrick Hugonneaux
KEYWORDS:
Aspherical Lens; Finite Element Model; Precision Glass Forming; Thermal Replication; Metrology
JOURNAL NAME:
New Journal of Glass and Ceramics,
Vol.3 No.1,
January
29,
2013
ABSTRACT: Worldwide, ESSILOR International provides customers with Progressive Addition Lenses (PAL), which replace bifocal lenses. Thermal replication is one process to produce glass moulds for PAL, using sagged glass on a ceramic slumping block. In this paper, thermal replication for producing PAL glass moulds is developed through 3D modelling and experimentation. Our numerical approach is validated by comparing it with experimentation on the global 3D topology of the sagged glass. It is also validated by using more severe optical comparison criteria, developed by ESSILOR International to analyze the conformity of their products. Through modelling, the thermal replication is analyzed by studying the evolving contact between the sagged glass and the ceramic slumping block during the thermal cycle and the glass flow on the upper side of the sagged glass.