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Article
Thermal Compensation and Fuzzy Control for Developing a High-Precision Optical Lens Mold
Author(s)
Chung-Ching Huang, Fu Zhang and Yi-Jen Yang
Full-Text PDF XML 544 Views
DOI:10.17265/2159-5275/2018.05.001
Affiliation(s)
Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan, ROC
ABSTRACT
Precision plastic
lenses often exhibit dimensional deviations due to the thermal expansion of the
mold during injection molding. Although this deviation is smaller in
micron-sized (1–5 μm) lenses, it exceeds the tolerance requirement of such
lenses. It is difficult to resolve this dimensional issue by using injection
molding parameters (e.g., melt temperature, injection speed, and hold pressure).
In this study, the thermal analysis of a mold was conducted, and it was
confirmed that the deviation of lens dimension was caused by the thermal
instability and thermal expansion of the mold. Due to the inconsistent heat
distribution of the fixed and the movable side of the mold, the position of the
location system was displaced approximately 1 to 5 μm. In this study, thermal
compensation technology for this the mold was investigated. The temperature on
both sides of the mold was measured, and
mold temperature could be adjusted automatically using a control strategy based
on fuzzy theory. During the mold
preheating or mass production stage, the temperature on both sides of the mold
could be easily adjusted to quickly obtain the required temperature range. The
dilatation on both sides of the mold was revised to improve the alignment
accuracy of the cavity, and the decenter error of these injection lenses was
reduced to 1 μm. This technology can markedly improve the production yield and
efficiency of plastic products requiring an extremely high dimensional
accuracy.
KEYWORDS
Fuzzy control, temperature compensation, decenter error.
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