臺灣博碩士論文加值系統

由於放電加工表面會殘留再鑄層與微裂縫等缺陷，表面粗度品質也難達到精微模具製造需求，一般作法是於放電加工後再施以精密拋磨製程。本文嘗試將微細放電與微研磨整合於同一機台且同步於一道製程上，於微放電加工之同時以鑽石磨粒去除融熔層與再鑄層，而不必經細放電後再執行研磨加工。由於微細孔使用之微研磨棒一般採用電鍍製作，因此本研究修改金屬中心電化學加工實驗室開發之線上小型複合電鍍系統，將已修整之微細電極在不需拆裝下可接於同一機床上進行複合電鍍。實驗研究以0.1與0.3mm微刀具之複合電鍍為主，在5 mm 與10 mm鎳陽極環中心，研究適於執行同步複合放電研磨之刀徑尺寸及磨粒尺度實驗設計，並於微放電機上加裝一高速主軸，用以進行同步微放電與微研磨。實驗材料為厚度0.3mm薄片不鏽鋼SUS 304用以證實本製程之可行性與應用潛能。
本文經實測研究及計算在直徑0.3mm下進行微研磨其主軸使用之轉速約為20000 rpm。電鍍實驗使用之基材為鎳，鑽石顆粒為5～7μm，電鍍之電流密度為7 ASD，電鍍時間5min，在工件側邊5μm進刀深情況下已證實其同步微放電與微研磨之可行性，然而有二次放電現象發生於排屑不良之出口側；進刀深小於5μm以下，則發生純鎳基放電現象，進刀深達8μm以上則是磨粒因放電時鎳基耗損太快而失去握持基礎，發生殘餘的刀具母材將研磨過之表面再度進行放電加工。因此最佳微放電複合微研磨條件約為進刀深5μm，藉鎳基放電將鑽石磨粒露出，並修整刀具表面直到適於同步微放電研磨。本文最後以5 mm陽極環進行大顆粒9～11um電鍍，證實顆粒尺寸增加可有效提升研磨表面與二次放電改善，並進一步整理出欲達成數百微米以下同步微放電研磨之必須條件。

Although micro-EDM (electrical discharge machining) is emerging in the past decades, its low machining efficiency and the surface integrity are still main disadvantages to micro manufacturing fields. As recast layer, micro cracks and other defects usually remain on EDMed surface, it is difficult by micro EDM alone to meet subtle mold manufacturing needs. Industrial practice used to impose on grinding/polishing after EDM process, but that may cause difficulty in positioning accuracy and repeatability for micro machining. This paper attempts to integrate micro-EDM with micro-grinding and synchronized both of them in a single manufacturing process. In which, special micro tools are adopted to remove soften recast layer and micro cracks as micro EDM is progressing, rather than by performing fine grinding as a secondary process. Generally, polishing of micro holes in molds and dies need electroplated tool with metal substrate and diamond abrasive. An electroplating tank was retrofitted for co-deposition with 5 mm and 10 mm 5mm ring of anode nickel, and tungsten carbide micro-tool was dressed from 0.3~0.5 mm to 0.1~0.3 mm by WEDG (wire electrical discharge grinding) on a micro-EDM. The electroplating conditions are with current density 7 ASD for 3~5 minutes, depending on abrasive grains. A high speed spindle up to 30 KRPM is adopted for providing enough tangent velocity for grinding. Workpiece with SUS 304 steel sheet of 0.3 mm thick is adopted to confirm the feasibility of the process and its application potential.
Experimental result reveals that the simultaneously hybrid processes of micro EDM and mechanical grinding is feasible and effective in some operation conditions with several groups of abrasive grain size. For 5~7 μm of abrasive powder, a feasible grinding depth is about 5 μm from lateral side with 0.05A of EDM power. But there is some surface damage at the exit side due to secondary EDM which was caused by debris of EDM and grinding. And for a wedge workpiece, three phases of surface evolved from pure EDM, hybrid EDM grinding (grinding by dressed-up abrasive diamond) to re-burning EDM (with new nickel substrate after EDM grinding) were observed along work surface. Finally, 9～11 μm grain size of diamond powder was deposited with 5mm ring of anode nickel for further testing. It was verified larger particle size improves grinding surface much better than smaller one with sufficient debris expelling and less secondary EDM discharging. Furthermore, necessary conditions for simultaneously hybrid micro-EDM grinding of several hundreds of micro meter workpiece are proposed through analysis and discussion.

摘 要
ABSTRACT
誌謝
目錄
圖目錄
表目錄
符號說明
第一章 緒論
1-1前言
1-2文獻回顧
1-3研究目的與方法
第二章 基本原理
2-1放電加工原理
2-1-1放電加工基本原理
2-1-2微細放電加工
2-1-3放電加工參數影響
2-1-4線放電研削加工法
2-2電鍍沉積原理與機制
2-3複合電鍍原理
第三章 實驗配置
3-1實驗設備
3-1-1微放電加工機系統
3-1-2線放電研削機構
3-1-3高速主軸系統
3-1-4小型複合電鍍系統
3-1-5 CCD量測系統
3-1-6光學顯微鏡
3-1-7 掃描式電子顯微鏡
3-2 實驗材料
3-3實驗規劃
3-3-1電極修整與高轉速放電測試
3-3-2線上複合電鍍備製微研磨電極
3-3-3同步微放電與研磨之證實與應用
3-4實驗參數
3-4-1微電極WEDG修整參數
3-4-2複合電鍍沉積加工
3-5實驗流程
第四章 實驗結果與討論
4-1 高轉速微放電加工之放電間隙
4-2 複合電鍍
4-2-1 電鍍參數
4-2-2電鍍表面
4-3 同步複合放電研磨
4-3-1 單邊同步放電與研磨
4-3-2 單邊進深量觀察
4-3-3 研磨刀具電極耗損
4-4 同步放電研磨排屑問題
4-5討論
第五章 結論
參考文獻
附錄一
作者簡歷

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