衣架型模具最佳化設計

Abstract

衣架型模具廣泛的應用在薄膜、片狀等製品的壓出。此模具的特徵為內部分歧管的形狀宛如一個衣架，管內的溝深變化由中心至兩端是由深到淺，其目的是為了使從入口導管進入的流體能夠均勻的分布於整個成形區。 設計一個衣架型模具使用了四個參數，分別為轉型區入口半徑、轉型區末端半徑、轉型區之夾角、狹縫之厚度，本文以一維流動分析的方法配合田口法進行上述四個條件的搜尋工作。以流量均勻度、總壓力降以及滯留時間作為判定模具優劣的性質。再針對搜尋所得的幾何形狀參數使用有限元素的方法進行三維流動的分析，最後經由分析的結果來確認此衣架型模具設計參數的適用與否。 由模擬結果的可知，以此流程的模具設計方法可以用為訂定衣架型模具的形狀。在本研究中對不同的剪薄係數以及模具寬度，須適當的加長或減少模唇即可達到要求的流量均勻度。

The coat hanger die is usually used in the film and sheet extrusion. The main characteristic of die lies in the fact that a manifold with the coat hanger shape exists in the die. The diameter of manifold is deeper in the center, and become gradually shallower to walls two side, thus allowing the fluid from the die entrance to distribute uniformly to the entire width of die. Four design parameters which are inlet and end radius of manifold, the angle of manifold and the thickness of die slit, were utilized to design the coat hanger die. One dimensional flow analysis and Taguchi method were used to search for the suitable values for four parameters. Then the performance of coat hanger die can be determined according to flow uniformity, total pressure drop and residual time. Subsequently, the resultant parameters were introduced proceed the three dimensional flow analysis. Finally the result of flow analysis can be used to confirm whether the resultant parameter are optimal for the design of coat hanger die. The simulation result showed that based on the foregoing approaching method is suitable for design of coat hanger die. In this study, proper change of die lip length can achieve the requirement of flow uniformity based on different values of power law in indices and die width.