Reducing service stress of the injection-molded polycarbonate window by optimizing mold construction and product structure

摘要

Many injected engineering polymer structures have to suffer the external load conditions (thermal load, impact load, etc.). In this case, service-induced stress concerns safety of human and the plastic engineering structure. In this study, geometrical design factors are connected with the engineering service stress of the polycarbonate (PC) window which is in thermal and pressure load conditions for the first time. The mold is constructed by an injecting gate with six design parameters and a type of spherical spiral conformal cooling system. The thickness of the product cavity is characterized by a linear function. Molding defects (warpage and residual stress) are taken into consideration sufficiently. In order to reduce the service stress, kriging surrogate model is employed to interpolate the implicit service stress function with respect to 14 geometrical design parameters, expected improvement function optimization method is used to search the optimum result, and log-exponential smoothing function method is used to simplify the multi-constraints. The comparison shows that the service stress is affected by the mold construction greatly, and the optimized mold and product design scheme are preferred to improve the service quality of the PC window.