Optimal design of heating system in rapid thermal cycling blow mold by a two-step method based on sequential quadratic programming

The blow molded parts made of engineering resins usually possess poor surface quality, and thus cannot satisfy the requirement of high-gloss appearance in some applications. For this reason, a rapid thermal cycling extrusion blow molding (RTCEBM) technology was developed, the process principle was presented and its process procedure optimization was also analyzed. Aiming at obtaining uniform temperature distribution on both mold cavity and core surfaces, a two-step optimization method based on sequential quadratic programming (SQP) algorithm was proposed for designing the heating system in RTCEBM mold, and its effectiveness was demonstrated by optimizing the electric-heating system for the RTCEBM mold of an automotive spoiler. After optimization, the maximum core surface temperature difference is reduced by 77% from the initial value of 22.06 °C to the optimal value of 5.05 °C; meanwhile, the molding process coordination can also be ensured. This work may provide an effective method to optimize the heating system for these molds with cavity and core sides to be heated simultaneously.