注塑模具近随形高光面壳计算

建立注塑模具近随形高光面壳厚度的计算方法.模拟分析注塑模具型腔表面曲率对传热的影响,利用Matlab拟合出型面曲率-温度关系公式;以平壁传热公式为基础,研究具有1维曲率、2维同向曲率及2维反向曲率等形状的型面,引入曲率影响系数,建立高光面壳厚度的计算公式与迭代算法.发现同时刻分别在高光面壳内外侧加热时,所达到温度的乘积均为一定值.将所得公式和算法应用于模具型腔表面,得出的近随形仿真结果表明,依据近随形高光面壳厚度计算方法得到的型腔表面温度分布误差小于3℃,低于工程中所要求的5℃以内的误差.实验证明,该算法合理,可以满足工程要求,为高光无痕注塑模具设计提供了简便实用的手段.

Computational formula for approximately conformal highlight shell of plastic injection mold

In order to determine the distance between heating channels and mold cavity more simply and accurately,a computational formula for approximately conformal highlight shell of plastic injection mold was established.The influence of the curvatures of plastic injection mold cavity surfaces on heat transfer was analyzed by simulation.A relative formula on cavity surface temperature with respect to curvature was simulated using Matlab.Then,on the basis of flat wall transient heat-transfer formula and setup of the curvature coefficient,the expression of the highlight shell thickness and its iterative algorithm were proposed for one-dimensional,two-dimensional same-direction and two-dimensional reverse-direction curvature’s mold cavity surfaces.The analysis results show that when the same highlight shell was heated respectively outside and inside at the same time,the product of the two cavity surface temperatures is always a fixed value.This value can be computed according to the heating time.No matter equidirectional or reverse,the second curvature’s magnitude has no influence on the heat transfer of the double-curvature highlight shell.But the second curvature’s presence has a significant effect.Finally,the formula was used on the given mold cavity surface and the simulation results were gained.Experimental results indicate that the temperature distribution error on the cavity surface is less than 3 ℃ and it is within the 5 ℃ error range.The formula is reasonable and can meet the mold design requirements.This can provide a powerful method for the design of weldless plastic injection mold.