NUMERICAL SIMULATION OF TRANSPORT PROCESSES IN INJECTION MOLD-FILLING DURING PRODUCTION OF A CYLINDRICAL OBJECT UNDER ISOTHERMAL AND NON-ISOTHERMAL CONDITIONS

摘要

In this paper, numerical simulation of injection mold-filling during the production of a cylindrical object under isothermal and non-isothermal conditions is presented. The material of the object is low density polyethylene(LDPE) following power-law viscosity model for non-zero shear rate zone. However, where shear rate becomes zero, "zero-shear viscosity" value has been used. Three cases have been considered, namely(i)Isothermal filling at constant injection pressure(ii) Isothermal filling at constant flow rate and (iii)Non-isothermal filling at constant flow rate. For the case-(iii), the viscosity of LDPE is also a function of temperature. The material of the mold is steel, For the non-isothermal filling, the concept of melt-mold thermal contact resistance coefficient has been incorporated in the model. The length and diameter of the body in all three cases have been taken as 0.254 m and 0.00508 m respectively. The finite-difference method has been used to solve the governing differential equations for the processes. The results show excellent agreement with the corresponding analytical solutions for the first two cases showing the correctness of the numerical method. The simulation results for non-isothermal filling show physically realistic trends and lend insight into various important aspects of mold-filling including frozen skin layer.