複合金屬板件冷輥接合與板液壓製程之分析

Abstract

本研究針對複合金屬薄板，分為冷輥接合，成型極限及板液壓製程等三部分進行深入探討。研究首先探討複合金屬薄板冷輥軋接合製程，針對不同初始厚度及減縮率之複合金屬薄板，利用剛塑性有限元素法，考慮熱傳導、塑性熱及摩擦等熱力項，計算鋁/銅複合金屬薄板之介面溫度，比較不同參數下之差異。結果指出，高輥速、高減縮率及非對稱輥速等，將可提高介面溫度，有助於複合金屬薄板之接合。 其次，應用實驗成型極限圖預測複合金屬薄板之破裂，由成形極限圖可以比較出，厚度減縮率(初始厚度)將影響鋁/銅複合金屬之成型性，而後搭配深引伸試驗比較模擬結果，由結果指出，實驗成型極限圖確實可作為預測複合金屬薄板之破裂。 針對複合金屬薄板之應用，本研究利用板液壓製程來提高複合金屬薄板之成形性。研究中透過有限元素分析，探討鈦/鋁複合金屬薄板於不同製程參數下之厚度減薄率，在數值分析中，本研究提出一虛擬薄膜之概念來應用於數值分析之模型，能夠真實模擬出液壓作用於試片之變化；並提出預鼓脹製程及模具修整的方式，藉此降低鈦/鋁複合金屬薄板之厚度減薄情況，並有效降低加工道次與模具成本。

This study comprises three sections that include cold roll-bonding, forming limit diagrams (FLDs), and sheet hydroforming (SHF). First, the bonding performance of Al/Cu clad metal sheet with different initial thickness and reduction rate were discussed. The heat flux calculation with thermal conduction, plastic heat and friction consideration were adopted in finite element analysis (FEA). The temperatures of clad metal sheet at maximum reduction region were obtained by rigid-plastic FE code (DEFORM-2D), and then the temperature distribution of Al/Cu clad metal sheets with different combinations of process parameter were determined. The simulation results pointed out that higher rotation speed, higher reduction rate, and asymmetrical rotation are positive to improve the bonding performance for clad metal sheets. The possibility of applying FLDs to fracture prediction of clad metal sheets is examined. The forming limits of Al/Cu clad metal sheets with different thickness reduction are investigated via FLD test. Moreover, deep drawing tests are carried out to compare the numerical results. The results pointed out that the fractures of clad metal sheets are predicated by experimental FLDs. For clad metal sheet application, the SHF was adopted to improve the formability of Ti/Al clad metal sheet used in 3C product housings. Some significant process parameters were analyzed for improving formability of clad metal sheet by FEA. In numerical simulation, a virtual film technique was proposed to realistically approach the hydraulic loading for SHF. And pre-bulging and tool modification are proposed to reduce thinning ratio of Ti/Al clad metal sheet, operation stage, and tooling cost.