Compression Molding of Aspherical Glass Lenses–A Combined Experimental and Numerical Analysis

Yi, Allen Y.; Jain, Anurag

doi:10.1111/j.1551-2916.2005.00137.x

Cited by 208 publications

(126 citation statements)

References 15 publications

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“…The introduction of glass molding process (GMP) to the precision optics industry has made it possible to manufacture high precision aspherical optical components at a high volume [1][2][3][4][5]. During glass molding process, the mold surface directly contacts with glass at an elevated temperature higher than glass transition temperature (Tg) [6].…”

Section: Introductionmentioning

confidence: 99%

Anti-sticking Re-Ir coating for glass molding process

et al. 2015

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a b s t r a c t a r t i c l e i n f oThe sticking of glass to the dies is a critical problem in glass molding process which limits the quality of products and lifespan of mold. Three kinds of protective coatings, including monolayer Re, Ir and Re/Ir multilayer were designed to mitigate the sticking and to improve the lifespan of mold. The interaction between barium crown optical glass and WC/Co mold materials (Co-10 at. %) with these three protective coatings was investigated. The results demonstrated that anti-sticking performance of multilayer coating is better than that of monolayer Re, Ir coating. The addition of interfaces resistance in multilayer is the main reason for improvement of antisticking ability of multilayer Re/Ir film. It was also verified that the Re/Ir multilayer coating possesses the highest nanohardness (24.5 GPa), as well as the largest wetting angle (168.1°).

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Section: Introductionmentioning

confidence: 99%

Anti-sticking Re-Ir coating for glass molding process

et al. 2015

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“…This paper is about numerical modelling of thermal replication, so we can also note the research of Dr. A. Yi, Associate Professor in the Ohio State University, about high-precision glass compression for optical components [11][12][13]. The research of Dr. Yi developed a laboratory apparatus for high-precision glass compression from an experimental perspective [11].…”

Section: Introductionmentioning

confidence: 99%

3D Modelling of Thermal Replication for Designing Progressive Glass Moulds

Lochegnies¹,

Moreau²,

Hanriot³

et al. 2013

NJGC

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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.

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“…Some used measured thermo-viscoelastic properties of the materials (BK-7 and TaF-3 [75]), obtained the viscoelastic property of glass by using the relaxation data from a cylinder compression test with the assumption of incompressibility [76], or treated glass as an elasto-viscoplastic material to account for the strain rate effect [79]. In most of these works the temperature-dependent rheology was modeled by the classical phenomenological Vogel-Fulcher-Tammann equation [37] or the thermos-rheological simple assumption [75,77], in which the parameters need to be obtained by curve fittings to a series of viscosity tests. Recently, a method was proposed for identifying the shear relaxation modulus and the structural relaxation function via measuring the time variation of the glass plate thickness [80].…”

Section: Constitutive Modeling Of Optical Glassmentioning

confidence: 99%

“…The technique of precision glass molding (PGM) has been developed for the manufacture of aspherical and irregular glass optics [37][38][39]. This technique is based on the softening of glass in its super-cooled liquid region which is above the glass transition temperature T g [40].…”

Section: Introductionmentioning

confidence: 99%

Precision glass molding: Toward an optimal fabrication of optical lenses

Zhang

Liu

2017

Front. Mech. Eng.

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It is costly and time consuming to use machining processes, such as grinding, polishing and lapping, to produce optical glass lenses with complex features. Precision glass molding (PGM) has thus been developed to realize an efficient manufacture of such optical components in a single step. However, PGM faces various technical challenges. For example, a PGM process must be carried out within the super-cooled region of optical glass above its glass transition temperature, in which the material has an unstable non-equilibrium structure. Within a narrow window of allowable temperature variation, the glass viscosity can change from 10 5 to 10 12 Pa$s due to the kinetic fragility of the super-cooled liquid. This makes a PGM process sensitive to its molding temperature. In addition, because of the structural relaxation in this temperature window, the atomic structure that governs the material properties is strongly dependent on time and thermal history. Such complexity often leads to residual stresses and shape distortion in a lens molded, causing unexpected changes in density and refractive index. This review will discuss some of the central issues in PGM processes and provide a method based on a manufacturing chain consideration from mold material selection, property and deformation characterization of optical glass to process optimization. The realization of such optimization is a necessary step for the Industry 4.0 of PGM.

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Compression Molding of Aspherical Glass Lenses–A Combined Experimental and Numerical Analysis

Cited by 208 publications

References 15 publications

Anti-sticking Re-Ir coating for glass molding process

Anti-sticking Re-Ir coating for glass molding process

3D Modelling of Thermal Replication for Designing Progressive Glass Moulds

Precision glass molding: Toward an optimal fabrication of optical lenses

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