Injection molding is a cyclic process used for the fabrication of thermosetting and thermoplastic articles. The thermoplastic polymer is melted and injected into the cavity, where it is molded under pressure and ejected after solidification. The amount of polymer mass contained in the cavity is the part weight. The control of part weight is important to ensure quality injection molded parts. The part weight is determined by the state of the polymer at the time the cavity gate freezes. The bulk temperature and the peak cavity pressure at the gate are used to characterize this state. / Measuring internal polymer temperature profiles in the injection mold cavity during molding is extremely difficult. This work presents a method which combines measurements of cavity surface temperatures, cavity pressure, and on-line calculations for estimating temperature profiles inside the cavity. These profiles are then used to estimate the bulk polymer temperature. Fitting the cycle-to-cycle values of bulk polymer temperature and peak pressure to a Tait equation of state yields a model to predict part weights. / The part weight is controlled through the use of a control strategy for the cavity pressure and the part weight model, together with the on-line estimation of the bulk temperature. A self-tuning algorithm with an observer is employed for controlling the cavity pressure time profile to a set point trajectory. The dynamics and control of the bulk temperature are also studied.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.40273 |
| Date | January 1996 |
| Creators | Varela, Alfredo E. (Alfredo Enrique) |
| Contributors | Kamal, M. R. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001499573, proquestno: NN12504, Theses scanned by UMI/ProQuest. |
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