木塑挤出成型特性分析与影响因素数值仿真研究

目的]为木塑型材生产提供合理的工艺控制参数,提升木塑挤出型材的质量。方法]针对木塑挤出成型工艺控制问题,从木塑熔融体到挤出成型的工艺特性角度进行了分析研究,重点得出了模具域熔融体流场(温度分布、压力分布)与剪切率(流速)的关系特性及工艺阀值特征。通过建立单螺杆挤出机计量段和法兰处三维计算模型,对木塑挤出成型的若干典型工况流场进行了数值仿真。结果]在一定的工艺阀值条件下,加热段的温度扰动对熔融体流场影响不大,而螺杆转速对流场影响较大,随着螺杆转速的增大,计量段压力逐渐减小,剪切率线性增大,粘度减小。结论]验证了该文分析结论的正确性和一致性,根据分析结果得到较理想的木塑挤出工艺控制参数。

Numerical Simulation on Characteristic and Influencing Factors of Wood Plastic Composite Melt in Extruder

Objective ] The paper was in order to achieve better controlling parameters of extruder, so as to improve the guality of wood plastic ex- trusion profiles. Method] Focusing on process control of WPC extrusion,this paper studyed from the angle of WPC melt and process characteris- tics of extrusion molding, to get distribution curve and process threshold value of mould segment in flow field （ temperature field, pressure field） of melt and screw speed （velocity）. numerical simulation on flow field of some typical working conditions of WPC extrusion, by constructing three-di- mensioal computational modelling of the metering section and flange of single screw extruder. Result ] Experimental results show that heating tem- perature little influences flow field while revolving speed greatly influences flow field with screw speed increases,pressure of metering section de- creases,shear rate increases and viscosity decreases, under the condition of process threshold. Conclusion ] Result verifies the correctness and consistency of the conclusion,according to results of analysis,better controlling parameters of extruder are achieved.