A micro-simulation of heat and fluid flow to determine thermal fluctuation at the mold/plastic interface during plastic injection molding.

摘要

In most of Computer-Aided-Engineering (CAE) packages used in injection molding, the assumption of an isothermal boundary and/or perfect thermal contact along the mold wall interface is very commonly used to facilitate the filling flow analysis as well as the thermal analysis of the process. Each analysis is carried out as a separate work. The objective of this thesis is to bring the cavity domain of the plastic part and the mold part together as a composite domain, to take the thermal resistance of the interface into account and to simulate the basic stages of the total cycle time of injection molding, especially the thermal characteristics of the interface. A two-dimensional mathematical model has been developed using a generalized Newtonian fluid for the problem. A stable finite difference method (FDM) scheme has been developed with an interpolation approach for the streamline velocity profile, instead of the iterative method which is implemented by many researchers in dealing with this type of analysis. The program analysis in this thesis can determine the cross-sectional velocity profile of the flowing plastic along the flow-direction during the filling stage. The effects of varying the contact conductance, part thickness, injection speed and mold temperature were examined. The results of the thermal analysis show that for the filling flow, the isothermal cavity boundary should be relocated somewhere inside the mold wall, away from the cavity surface. For a constant contact conductance Hr, the discontinuative temperature gap at the interface diminishes hyperbolically with time.Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses u26 Major Papers - Basement, West Bldg. / Call Number: Thesis1991 .N577. Source: Masters Abstracts International, Volume: 30-04, page: 1453. Co-Advisers: D. F. Watt; N. Zamani. Thesis (M.A.Sc.)--University of Windsor (Canada), 1991.