Abstract: In variotherm injection molding, the mold temperature can be changed according to the requirement of the process. If the mold temperature keeps higher than the resin glass transition temperature during filling stage and then rapidly cool down the shaped resin melt under the ejection temperature during cooling stage, the problems such as weld mark, jetting mark, flow mark, warping and floating fibers. in conventional injection molding can be thoroughly solved without increasing molding cycle time. Based on in-depth study on the principle of variotherm injection molding process, a new mold temperature control technology with high temperature steam for heating the mold is presented. The process for this new molding technology is proposed and the dynamic mold temperature control system is also designed and built. Four different mold design schemes are proposed by research on the characters of the mold structure of variotherm injection molding with steam heating. To pursuit the goal of reducing molding cycle time and improving temperature uniformity, the mold structure is optimized through temperature response simulation for the heating and cooling stages of variotherm injection molding process. The simulation results are verified through the trial production of a LCD TV panel with variotherm injection molding.

Key words: Heat response analysis, Optimization of mold structure, Steam-assisted heating, Variotherm injection molding