结晶性注塑平板制品冷却时间的确定

Decision of Cooling Time for Injection Molded Slabs of Crystalline Plastics

从传热学基本原理出发,推导出结晶性平板状注塑制品冷却时间的几种计算方法。对于PP,在相同条件下,利用分离变量法对简化的一维传热模型进行求解,得冷却时间τ为7 5s;对一维相变移动边界模型,解析解法采用固相精确求解与液相近似求解相结合的方法,得τ为23s;数值解法采用了焓法,得τ等于23 05s。最后举例讨论了数学模型与实际注塑加工的差距。这些对结晶性聚合物注塑加工具有一定的指导作用。

Several methods to determine the cooling time of injection molded slabs of crystalline plastics are discussed based on the theory of heat transfer.Under the same condition,the cooling time of PP,designated as τ,is 75s after calculating the simplified onedimensional heat transmission model by means of the method of separation of variables. There are analytic and numerical solutions to solve the problem of phase transition with moving boundary,τ is equal to 23s and 2305s respectively.Accurate solution of solid phase combined with approximate one of liquid phase is adopted in analytic solution and enthalpy method is applied in numerical solution.In addition,the comparisons between the practical injection molding and mathematical model are illustrated. 