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Research Papers

Numerical Evaluation on the Curve Deviation of the Molded Glass Lens

[+] Author and Article Information
Jian Zhou

Department of Precision Machinery and
Precision Instrumentation,
University of Science and Technology of China,
Hefei, Anhui 230026, China
e-mail: zhoujian@mail.ustc.edu.cn

Mujun Li

Department of Precision Machinery and
Precision Instrumentation,
University of Science and Technology of China,
Hefei, Anhui 230026, China
e-mail: lmn@mail.ustc.edu.cn

Yang Hu

Department of Precision Machinery and
Precision Instrumentation,
University of Science and Technology of China,
Hefei, Anhui 230026, China
e-mail: huy2007@mail.ustc.edu.cn

Tianyi Shi

Department of Precision Machinery and
Precision Instrumentation,
University of Science and Technology of China,
Hefei, Anhui, 230026China
e-mail: sty@mail.ustc.edu.cn

Yueliang Ji

Department of Precision Machinery and
Precision Instrumentation,
University of Science and Technology of China,
Hefei, Anhui 230026, China
e-mail: jiyue@mail.ustc.edu.cn

Lianguan Shen

Department of Precision Machinery and
Precision Instrumentation,
University of Science and Technology of China,
Hefei, Anhui 230026, China
e-mail: lgshen@ustc.edu.cn

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received May 1, 2013; final manuscript received March 29, 2014; published online August 6, 2014. Assoc. Editor: Brad L. Kinsey.

J. Manuf. Sci. Eng 136(5), 051004 (Aug 06, 2014) (11 pages) Paper No: MANU-13-1202; doi: 10.1115/1.4027342 History: Received May 01, 2013; Revised March 29, 2014

The compression molding of precision glass lens is a near net-shape forming process for optical components fabrication. The final profile curve accuracy is one of the most crucial criterions for evaluating the quality of the molded lens. In this research, our purpose was focused on the evaluation of the molded lens curve deviation. By incorporating stress relaxation and structural relaxation model of glass, numerical simulations of the whole molding process for fabricating a planoconvex lens were conducted by utilizing the commercial software msc Marc. The relationship of the three variables, i.e., the lens curve deviation, the mold curve deviation, the gap between the lens and the lower mold, was discussed and the evolution plots with time of the three variables were obtained. Details of the thermal boundary conditions were discussed by considering the contact heat transfer behavior. Then the essentiality of a small gap between the molds and the molded lens after releasing the upper mold was demonstrated. In details, the sensitivity analysis of the processing parameters was conducted, such as the releasing temperature, the cooling rate in the annealing and fast cooling stage, respectively, and the magnitude of the hold-up force. The results showed that the glass lens curve deviation was not sensitive to the choices of the releasing temperature and the cooling rate. What's more, the results indicated that the curve deviation decreased with the hold-up force increasing. Finally, with all the details considered, the final simulation results were presented accurately with good reason.

Copyright © 2014 by ASME
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References

Figures

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Fig. 1

Geometric dimensions and mesh generation of the molds and the glass gob

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Fig. 3

Schematic illustration of the molding process

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Fig. 2

Boundary conditions of different stages

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Fig. 10

Equivalent von Mises stress versus time in glass lens

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Fig. 11

Glass lens curve deviation history plot with time

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Fig. 12

Final glass lens curve deviation

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Fig. 6

Glass lens curve deviation of different increments

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Fig. 5

Evolution plot with time of glass lens curve deviation

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Fig. 4

Illustration of glass lens curve deviation: (a) initial situation and (b) final situation

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Fig. 7

Temperature distribution for near contact behavior study: (a) near contact off, (b) dnear = 0.1 mm, and (c) dnear = 0.2 mm

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Fig. 9

Temperature distributions within lens for different initial gap values: (a) initial gap set as zero or 0.1 mm and (b) initial gap set as 0.2 mm

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Fig. 13

Releasing temperature sensitivity study: (a) nodal temperature, (b) glass curve deviation history, and (c) glass curve deviation history with temperature

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Fig. 14

Cooling rate sensitivity study for the annealing stage: (a) nodal temperature, (b) the highest and lower temperature within the lens, (c) Comp 22 of stress history plot with temperature, and (d) glass curve deviation history plot with temperature

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Fig. 15

Cooling rate sensitivity study for the fast cooling stage: (a) nodal temperature and (b) glass curve deviation history plot with time

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Fig. 16

Hold-up force sensitivity study: (a) glass curve deviation history plot with time and (b) the final glass lens curve deviation

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Fig. 17

Final simulation results: (a) temperature distribution (b) equivalent von Mises stress distribution, (c) history plot of deviation values with time, and (d) final glass lens curve deviation

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Fig. 8

Glass lens curve deviation for near contact behavior study

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