The use of evanescent wave fluorescence spectroscopy in process control of the liquid molding process
Conference
·
OSTI ID:109733
- National inst. of Standards and Technology, Gaithersburg, MD (United States)
- Johns Hopkins Univ., Baltimore, MD (United States). Materials Science Dept.
Fluorescence has been demonstrated to be an accurate measurement of resin cure and has been used in liquid molding as distal-end fiber optic sensors. Evanescent wave fiber optic sensors offer the additional advantage of sensing the cure deep within the preform and very close to the fiber surface. An economical optical fiber sensor has been developed with a refractive index in excess of 1.6, permitting evanescent wave monitoring of most typical liquid molding resins. A hierarchical control strategy is being developed for liquid molding processes that will use the cure measurement provided by the evanescent wave fluorescence sensor. Single input/single output control loops are implemented at the base level to regulate the mold temperature, the vacuum pressure in the mold, either the inlet flow or pressure during injection, and the final mold pressure. A model-based feedback controller is implemented to control the chemical cure and manipulates the setpoint of the temperature controller to achieve cure control. A general high-level controller is under development to optimize the process under a wide range of operating conditions.
- OSTI ID:
- 109733
- Report Number(s):
- CONF-950521--; ISBN 1-56676-313-4
- Country of Publication:
- United States
- Language:
- English
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