茂金屬聚乙烯吹袋模頭之最佳化設計

Abstract

茂金屬聚乙烯具有良好的機械性質，為一極具發展性的加工材料，但是低熔融強度與高剪切黏度卻是其在加工上的一大缺點。透過數學模式並配合田口法進行的模頭最佳化設計，可避免其熔融強度不夠及膠料過熱的現象。 螺旋式心軸模頭共有七個設計參數，分別為軸心直徑、螺旋溝的數目、起始溝寬、起始溝深、螺旋角、軸心傾斜角及間隙。本文以茂金屬聚乙烯為加工材料，透過二維流動數學模式並配合田口法以搜尋其最佳形狀參數，藉以探討在最佳化設計下的模頭性能表現，如流量均勻度、混合度及最大壓力降。另外評估模唇對模頭性能的影響，並以在等溫情況下搜尋之最佳形狀參數檢視其在非等溫情況下的性能表現與等溫情況下之差異。

Metallocence polyethylene(m-PE) is a fully potential material with well mechanical properties. But the poor melt strength and high shear rate viscosity are disadvantages in polymer application. Mathematic model combined with Taguchi method is a method for optimal design of spiral mandrel die to avoid the poor melt strength and the overheat of melt. There are seven parameters in designing the spiral mandrel die, which are the diameter of the mandrel, the number of the helical groove, the initial width of the helical groove, the initial depth of the helical groove, the helical angle, the taper angle, and the gap. With m-PE as a processing material, two-dimensional flow simulation and Taguchi method are combined to determine the optimal geometry value, and the performance of the die was discussed. In addition, the performance of the die was examined with die lips. Finally, the performance of the die was examined under nonisothermal condition and compared with under isothermal condition.