- 學位論文
單點鑽石車削加工於經電漿滲層處理之S420不鏽鋼之研究
Investigation of single point diamond turning of plasma surface treated stainless steel
摘要
近年來，有一些金屬例如鋁合金、無電鍍鎳跟銅（OFHC）已經可以經由鑽石車削達到次微米的公差及小於2nm的表面粗糙度（Ra），而且鑽石車削也可以加工硬脆材料例如Soda-lime玻璃、BK7、矽及Zerodur等材料的表面像鏡面一樣的表面精度。然而不鏽鋼及其他的鐵系金屬被歸類為不可鑽石車削的，因為藉由在鑽石與鐵金屬間產生的熱化學反應造成不可接受的刀具磨耗。近年來有研究將不鏽鋼試片在相當低溫的狀態（<450℃）用離子氮化來防止用盡在沃斯田鐵基材中的鉻以及得到一層用鐵原子與氮原子成型而成γ’-Fe4N的硬層。鑽石車削的的實驗在下列加工參數便完成：單晶鑽石刀具，最大切削速度180m/min，最大切深至4.5μm以及使用少量的無機油當作切削液。結果顯示在相同的參數下車削不鏽鋼時會獲得快速的刀具磨耗以及很差的表面精度，而車削經過離子氮化的試片會得到10nm以下的表面粗糙度以及沒有發現明顯的刀具磨耗。
並列摘要
For some years, it has been possible to diamond-turn certain metals such as aluminium alloy, electroless nickel, and copper(OFHC) to sub-micrometre figure tolerances and surface roughness better than 2nm Ra. It has also been achieved in diamond turning brittle materials such as soda-lime glass, BK7, silicon and Zerodur to mirror-like surface finishes. However, stainless steel and other ferrous metals are normally classified as not diamond turnable for the unacceptable tool wear caused by the thermal-chemical reaction between diamond and ferrous metals. In the present research, stainless steel specimens were plasma nitrided at a relatively low temperature (<450oC) to prevent the depletion of Cr content at the austenite matrix and to give a hardened layer where Fe atoms are bonded to nitrogen atom to form γ’-Fe4N. Diamond turning experiments were subsequently carried out under the following machining conditions: single crystal diamond tool, cutting speed up to 180 m/min, cut depth up to 4.5mm and light mineral oil as the cutting fluid. The results showed that, given the same machining conditions, while rapid tool wear and poor surface finish were obtained when turning the as-received stainless steel, surfaces with Ra better than 10 nm and no obvious tool wear were achieved when turning the plasma nitrided specimens.