英语翻译Blow molding is the third largest plastics processing te

英语翻译
Blow molding is the third largest plastics processing technique worldwide and is generally recognized to be one of the fastest growing areas in the plastics industry[1].One of the essential steps which constitutes the blow molding cycle is the inflation of the parison.The entire process of parison inflation occurs in two successive stages,namely,free inflation followed by confined inflation.The parison inflation process is highly complex,involving the interaction of several process variables,such as the inflation pressure,material characteristics,parison thickness distribution,and parison temperature profile.
There have been quite a few reports in the existing literaturre on the simulation of parison inflation[2--9].Ryan and Dutta[3] made an analytical treatment of the free inflation of a viscoelastic parison by assuming a one-dimensional isothermal deformation.This simplified analyses cannot be used to predict realistic shapes of the parison during its inflation.
The finite element method (FEM) has been used to simulate the inflation of parison over the last decade[4--9].However,modeling blow molding inflation process with the FEM requires that many of the most difficult aspects of the FEM be addtessed in the analysis.These difficulties arise because of large strains,large deformations,nonlinear material behavior and so on during the inflation of parison.
In this paper,a mathematical model has been derived for simulating the parison free inflation in the plastics extrusion blow molding.In order to evaluate the predictive capabilities of the model,the instantaneous images of parison inflation within a mold epuipped with glass side windowa have been obtained by using a video capture technique.
1 Theoretical Analysis
Consider the free inflation of an isotropic and incompressible annular parison with an uniform radius and thickness,and length 2L in the initial state,as shown in Fig.1.The parison is assumed to be treated as a membrane (with thickness much less than any radius of curvature) so that any change in the deformation variables across the thickness may be neglected.Gravity and surface tension effects are neglected.Cylindrical polar coordinate system(r,r,x) is taken and all puantities are independent of r because of symmetry.Amaterial particle that locates at (r,r,x) during inflation is originally at (r,r,x).The ends of the parison are at x=0 and x=2L,and there is symmetry about the plane x=L.