薄壁鎂合金筆記型電腦上蓋之壓鑄模澆流道設計分析

Abstract

現今之攜帶型3C電子產品，其設計發展逐漸朝向輕薄短小的方向，也使得此類產品的框架、結構件在材料的選用上，有越來越多採用鎂合金的趨勢。目前，此類鎂合金薄壁件的最主要生產方式為壓鑄方法。然而，採用壓鑄方法，由於高速充填的緣故，常容易發生捲氣的現象，使得鑄件內部有孔洞的缺陷。 本研究的目的，即在瞭解鎂合金薄壁鑄件在壓鑄過程，熔湯在金屬模穴中的流動情形，並以電腦軟體模擬熔湯在充填過程中的充填模式，期望預測出鑄件在充填過程中所可能會發生的缺陷。本研究採取了扇形澆口與錐形澆流道兩類型的澆流道系統，對薄壁筆記型電腦上蓋做澆流道系統的設計分析。扇形澆口的部分採取了不同的扇形長度對澆口寬度比與截面積減縮率，討論這兩項因子對充填模式的影響；錐形澆流道則探討澆口是否連續對充填模式的關係，並比較分析這兩類型澆流道設計對大平面薄壁壓鑄件熔湯充填之優缺點。

Consumer electronic product development is moving constantly. Materials accommodate these requirements must be light and strong, thus magnesium alloys with their light densities are often selected. One of the main manufacture methods for magnesium part is die casting. But because of the high filling speed in die casting, air entrapment which causes defects in the casting part is a common phenomenon. The purpose of this research is to study the flow behavior of molten magnesium alloy in the die cavity during die casting process. Commercially available computer software package (namely Flow-3D) is adopted for simulation of the filling process. Fan gate and tapered runner gating system for the thin-walled magnesium notebook LCD panel product was studied. Finally was compared and discussed the advantages and disadvantages with different types of runner and gating systems. It is found that tapered runner system a better filling process in die casting.