【摘要】 针对尼龙6(PA6)棒材挤出成型性较差的工程问题,实验研究了PA6材料的流变特性和挤出成型的合理温度区间,采用数值分析方法研究了PA6棒材挤出模具加热区流道结构特征参数对熔体温度分布和剪切速率的影响规律,分析了螺旋冷却水道的温度分布状况及冷却效果。结果发现,PA6挤出成型温度控制在230～240℃,能够有效保证其挤出成型性并避免材料降解;增大挤出模具加热区压缩段长度能够降低熔体黏性生热导致的温升和熔体局部剪切速率,增大释放段长度能够降低熔体局部的剪切速率,但是对熔体温升基本无影响;挤出模具采用螺旋冷却水道冷却定型,可以使PA6棒材的冷却更加均匀。通过改进挤出模具设计和冷却定型系统,有效改善了PA6挤出棒材制品的内在和外观质量。更多还原

【Abstract】 To solve the problem of poor extrusion properties of Nylon 6(PA6) rods, the rheological characteristics of PA6 and the proper temperature range for extrusion were explored experimentally. Numerical simulations were performed to study effects of structural parameters of the extrusion die heating zone on the temperature distribution and the shear rate of PA6 melts. Moreover, a spiral cooling channel was applied and its cooling effect was also analyzed numerically. It is revealed that the extrusion temperature plays an important role in molding quality. The temperature should be controlled in the range of 230 ℃ to 240 ℃, where the extrusion property is improved and the material degradation is also avoided. Increasing the length of compression section in the extrusion die heating zone can be used to reduce the temperature rise caused by viscous dissipation and the local shear rate of the melt. The increase of release section length in the heating zone reduces the local shear rate, but has little effect on the temperature rise. The spiral cooling channel in the extrusion die cooling zone makes the cooling of extruded rod more uniform. By improving the design of extrusion die and cooling system, the anti-pressure mechanical properties, the internal product property and the external texture of PA6 rods are apparently improved.更多还原