連續式六向等徑轉角反覆擠製機具之開發

Abstract

鎂合金具有質輕、堅固、美觀等優點，現今已廣泛運用在我們的生活周遭。但是鎂合金在常溫之塑性變形能力不佳，因此常透過半固態成形技術來增進鎂合金的成形性。而製作鎂合金半固態成形胚料時，利用等徑轉角擠製法來對鎂合金原素材進行晶粒細化，能對材料在半固態下的成形性有所幫助。 然而傳統等徑轉角擠製法有其缺點存在，尤其部分路徑無法連續擠製、溫度履歷不穩定、並且製程時間過長。 本研究開發了連續式六向等徑轉角反覆擠製機具，此機具利用六向油壓動力，可以不移動模具的情況下連續進行不同路徑與道次的連續轉角擠製、全程維持實驗溫度的穩定、並大量縮短了製程時間。 另一方面，透過連續式六向等徑轉角反覆擠製機具製作不同時間參數的試片，對其作半固態成形試驗。發現縮短等徑轉角擠製製程時間，可以降低對鎂合金半固態成形性的負荷。

Magnesium alloys are widely used in industrial fields because of its properties of light-weight and high strength. Due to the bad formability of the magnesium alloy at room-temperature, semi-solid forming process are often adopted as a method for fabrication of the alloys. To increase the formability of semi-solid forming billet, we use the ECAE (Equal Channel Angular Extrusion) process to achieve grain refinement of the magnesium alloy. Conventional ECAE have many disadvantages: First of all continuous extrusion is almost impossible in ECAE process; The temperature of the billet in the experiment isn’t constant and it takes too much time of the full ECAE process to carry out. In this research, we develop a continuous six-directions ECAE processing equipment. This equipment can perform the different routes and passes in six-directions continuously, without moving the die. Besides, we produced billets by continuous six-directions ECAE with different process time, and then apply these billet to semi-solid forming test. The result of the filling-rate shows that shorten the processing time of the ECAE will ceduce the formability load of the magnesium alloy in semi-solid state.