金字塔型之砌積式心軸模頭最佳化設計

Abstract

傳統螺旋軸心模頭廣為應用於高分子薄膜製造。良好的模頭設計，可增進流量均勻度和避免縫合線產生。提升產品的多重性質通常會採用多層模的設計。最新砌積式心軸共押模頭技術與傳統式共押模頭相比，砌積式心軸共押模頭有比較少的流體接觸表面積及模頭寬度。本文將採用二維控制體積法的流動模式，同時並配合田口法去分析以便快速找出金字塔型之砌積式心軸模頭之最佳幾何形狀。最後分別討論在等溫情況下搜尋之最佳形狀為基準,改變各個參數對模頭性能之影響及探討流體在螺旋溝中流動的情形。外模壁傾斜角對模頭性能之影響其結果顯示外模壁傾斜角對不同溝道數及不同材料的外模壁傾斜角增加到一定傾斜度之後流量均勻度和和混合度開始呈現遞減趨勢。

Conventional spiral mandrel dies are widely used in the production of polymeric films. Better die design can promote the flow uniformity and prevent the formation of weld line. The multilayer film is used to comproise different polymers to from a product with multiple properties. The new type of stackable coextrusion has less wetted area of fluid and the width of die compared with the conventional coextrusion die.In this study,a two dimensional control volume method in coordination with the Taguchi method,was utilized to optimize the geometric parameters of the pyramid type of stackable spiral mandrel die. Under the isothermal condition,the influence of each processing variable on the performance of die base on the optimal processing condition and the flow situation in the spiral channelwere investigated. With the different number of channels and various processing mateils the flow uniformity and mixedness increased to some certain extend then decreased as the inclinded angle of the outer die wall kept increasing.