Survey Of Present Lens Molding Techniques

Pollicove, Harvey M.

doi:10.1117/12.944475

Cited by 6 publications

(3 citation statements)

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“…(0 d m d 1). (2) Forming of the lens gob at 684 ºC (adiabatic process). Four-node quadrilateral elements were used to model all the objects.…”

Section: Model and Boundary Conditionsmentioning

confidence: 99%

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Numerical Simulation of Compression Molding of Aspherical Glass Lenses

Jain¹,

Yi²

2004

AIP Conference Proceedings

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Articles you may be interested inAnalysis of different compression-molding techniques regarding the quality of optical lenses Abstract. Compression molding has become a viable manufacturing process for medium to high volume production of aspherical glass lenses. The lack of fundamental understanding of the process and other technical issues ranging from thermal shrinkage to mold coating wear and long molding cycles have made this process unsuitable for industrial applications. In this research, the various stages of the lens molding process have been modeled to understand the effect of different molding parameters to the final lens quality (geometry). 2-D axisymmetric simulations of the glass molding process have been performed using a commercial Finite Element Method (FEM) code. Glass has been modeled as a Newtonian fluid and temperature dependent viscosity and the heat transfer at the glass mold interface have also been taken into consideration. One of the main objectives of this research was to include the effect of viscoelasticity (time dependent response of glass to mechanical load), into the simulation model. A limited number of experiments were also performed and a comparison of the predicted results has been made with the experimental data. Although the predicted results seem to be in qualitative agreement with the experimental data, further research needs to be performed on viscoelasticity, structural relaxation (time dependent response of glass to change in temperature), and non-Newtonian behavior of glass at high stress levels, in order to make FEM a more effective tool for process analysis and optimization.

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“…(0 d m d 1). (2) Forming of the lens gob at 684 ºC (adiabatic process). Four-node quadrilateral elements were used to model all the objects.…”

Section: Model and Boundary Conditionsmentioning

confidence: 99%

“…As an alternative to traditional glass optical manufacturing process, compression molding of precision aspherical optics can be an attractive approach [2]. In this process a glass gob is pressed in a single operation to form a finished lens.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Compression Molding of Aspherical Glass Lenses

Jain¹,

Yi²

2004

AIP Conference Proceedings

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“…Different techniques have been developed for high-precision lens moulding [1,2]. Thermal replication is one of them and is mainly used to produce progressive glass moulds, which are later used to manufacture plastic aspherical optical lenses.…”

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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Untersuchungen zum Einfluß von Schichtherstellparametern auf Hochtemperatur‐und Verschleißverhalten von PVD‐Schichten

Kleer¹,

Döll²

1993

Materialwissenschaft Werkst

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Nitridische Hartstoffschichten sind von Interesse fur dieverbesserung des Einsatzverhaltens von Werkzeugen fur die zahplastische Formgebung optischer Komponenten aus anorganischen Glasern. In der vorliegenden Untersuchung wurden AIN-und TiN-Schichten durch reaktives Zerstauben auf Stahl-, Hartmetall-, Glas-und Silicium-Substratmaterialien aufgebracht. Dabei wurden die Pro-zeBparameter: Gesamtgasdruck, Partialdrucke von Stickstoff und Argon, Abstand vomTarget zurn Substrat und Substrattemperatur variiert. Besonders wird auf die Beeinflussung der Schichtspannung durch die ProzeRparameter und auf das mechanische Verhalten von Schichten rnit unterschiedlichen Zug-bzw. Druckeigenspannungen eingegangen. Unter andere,m wurde beim AIN, hergestellt in DC-Tetroden-ProzeB, ein Ubergang von Zug-zu Druckspannungen bei Variation des Gesamtdruckes bzw. des Abstands zwischen Target und Substrat erreicht. Schichten rnit Druckeigenspannungen zeigten einen hoheren Widerstand gegen RiBinitiierung unter punktformiger Belastung und ein giinstigeres VerschleiBverhalten.lnvestigations on the effects of process parameters on the high temperature and wear behavior of W D coatings.Metal nitride coatings are of particular interest for the improvement of the service behavior of forming tools for the thermoplastic molding of optical components from anorganic glasses at high temperatures. In the present study AIN and TiN coatings were deposited on steel, glass and silicon substrates in reactive sputtering processes by variation of the process parameters total pressure, partial pressures of nitrogen and argon, substrate temperature and distance between target and substrate. In particular the effect of the process parameters on the film stresses as well as the mechanical behavior of films with various tensile and residual stresses have been analyzed. A transition from tensile to compressive stresses by variation of the total pressure and of the distance between target and substrate was obtained for AlN coatings prepared by a reactive d.c. tetrode process. In coatings with compressive residual stresses an increased resistance to microcrack initiation and improved wear behavior could be achieved.

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Survey Of Present Lens Molding Techniques

Cited by 6 publications

References 0 publications

Numerical Simulation of Compression Molding of Aspherical Glass Lenses

Numerical Simulation of Compression Molding of Aspherical Glass Lenses

3D Modelling of Thermal Replication for Designing Progressive Glass Moulds

Untersuchungen zum Einfluß von Schichtherstellparametern auf Hochtemperatur‐und Verschleißverhalten von PVD‐Schichten

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