Simulation of the 2D Injection Molding Process Using Unstructured Meshes

Author(s)

Kémelli Campanharo Estacio

• Document type: Master's Dissertation
• Press: São Carlos. , gráficos, ilustrações, tabelas.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Matemáticas e de Computação (ICMC/SB)
• Defense date: 2004-03-29

Examining board members

Norberto Mangiavacchi; Antonio Castelo Filho; João Flávio Vieira de Vasconcellos

• Advisor: Norberto Mangiavacchi
• Field of knowledge: Physical Sciences and Mathematics - Mathematics
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP
• Location: Universidade de São Paulo. Instituto de Ciências Matemáticas e de Computação. Biblioteca Prof. Achille Bassi; ICMSC/T; E79sp

Abstract

Injection molding is one of the most important industrial processes for the manufacturing of thin plastic products. This process can be divided into four stages: plastic melting, filling, packing and cooling phases. The flow of a fluid characterized by high viscosity in a narrow gap is a problem typically found in injection molding processes. In this case, the flow can be described by a formulation known as Hele-Shaw approach. Such formulation can be btained from the three-dimensional conservation equation using a number of assumptions regarding the injected polymer and the geometry of the mold, together with the integration and the coupling of the momentum and continuity equations. This approach, referring to limitations of the mould geometry to narrow, weakly curved channels, is usually called 2 1/2D approach. In this work a technique for the simulation of the filling stage of the injection molding process, using this 2 1/2D approach, with a finite volume method and unstructured meshes, is presented. The modified-Cross model with Arrhenius temperature dependence is employed to describe the viscosity of the melt. The temperature field is 3D and it is solved using a semi-Lagrangian scheme based on the finite volume method. The employed unstructured meshes are generated by Delaunay triangulation and the implemented numerical method uses the topological data structure SHE - Singular Handle Edge, capable to deal with boundary conditions and singularities, aspects commonly found in numerical simulation of fluid flow. (AU)