臺灣博碩士論文加值系統

多晶鑽石(Polycrystalline Diamond，PCD)是工業廣泛應用的切削刀具材料，具備了極高的硬度、耐磨性、優越的強度及韌性。本研究針對鎳基多晶鑽石(Ni-PCD)材料進行研究，因其金屬含量較一般PCD及導電PCD少，導電性較差，有鑒於各種形貌及精度需求，故不採用傳統加工方式，而以線切割放電方式加工，但以線切割放電進行加工時，易產生放電火花不足，導致加工困難。本文藉由調整WEDM各項加工參數及採用銅片覆層方式，探討線切割放電加工後之各項特性。研究結果發現，線切割放電加工使用電極線徑ø0.15mm、ø0.2mm之放電能量不足，僅能以線徑ø0.25mm電極線徑加工鎳基多晶鑽石。鎳基多晶鑽石本體導電不良但非絕緣體，其金屬鎳分布均勻，經調整放電時間、休止時間、短路放電時間、短路休止時間及伺服參考電壓等加工參數後可有效改善其加工機制，減少斷線及不連續切削之現象。鎳基多晶鑽石應用銅片覆層作為輔助電極時，可增加工件表面導電性，幫助產生放電火花，達到加工目的，亦可有效減少PCD的熱影響區，當以較小之加工能量加工時，薄銅片可增加其加工速度，但無法得到較好之表面粗糙度。覆層薄銅片對多晶鑽石之表面形貌及精度，以覆層銅片厚度為0.5mm之效果最佳。本研究對於線切割放電加工三種多晶鑽石之加工機制與現象之觀察，有助於了解不同形式多晶鑽石之放電加工特性，進而利用不同加工特性，以調整最佳放電加工參數，期能獲得更有效、更快速的加工，並達到加工速度與加工精度、品質兼具的最佳目標。

Polycrystalline Diamond (PCD), widely used industrial cutting tool material, with a high hardness, wear resistance, excellent strength, and toughness. This study, Ni-PCD materials metal content less than S-PCD and EC-PCD, poor electrical conductivity, for needs of different morphologies and accuracy, it isn’t using the traditional processing methods, but for wire electrical discharge machining, in WEDM processing, it is hard to produce sparks, leading to processing difficulties. By adjusting parameters of WEDM and using the copper multiple covering. The results showed of the electrode wire of ø0.15mm and ø0.2mm due to the discharge energy shortage. But only the electrode wire of ø0.25mm was processing of Ni-PCD with poor electrical conductivity, it isn’t a insulator with nickel distribution. To adjust on time, off time, arc on time, arc off time and servo voltage, and other processing parameters can effectively improve the processing mechanism to reduce the region of HAZ and not continuous cutting phenomenon. Multiple copper covering applied as an assisting electrode, increase surface conductivity, help generate sparks, to processing purposes, also effectively reduce the region of HAZ, when the processing power in smaller processing , thin sheet of copper will increase its processing speed, it can’t get better surface roughness. Cover thin copper on the morphology of PCD and accuracy to 0.5mm thick copper covering of the best. For this study, three wire electrical discharge machining of PCD processing mechanism and the phenomena observed, help to understand different forms of electrical discharge machining of PCD properties, then the use of different processing characteristics, to adjust the optimum discharge machining parameters, it can be more efficient, faster processing, and achieve good quality of processing speed and processing accuracy.

致謝 ii
摘要 iii
ABSTRACT iv
目錄 v
表目錄 viii
圖目錄 viii
符號表………………………………………………………………………………xii
1.前言 1
1.1研究背景 1
1.2研究目的 4
1.3研究方法 7
2.文獻回顧 8
2.1多晶鑽石形成 8
2.2加工方法 11
2.3放電加工 13
2.4放電加工參數介紹 18
2.5放電加工特性 19
3.實驗設備與規劃 26
3.1實驗設備 26
3.2實驗材料 29
3.3實驗方法 32
4.結果與討論 37
4.1放電加工PCD的原理 37
4.2加工參數對電極加工效率的影響 41
4.2.1電氣參數改變之物理意義 42
4.2.2加工線極線徑 43
4.2.3不同加工電壓對加工效率的影響 46
4.2.4不同加工電壓對熱影響區、表面隅角形貌與表面粗糙度之影響 49
4.3覆層加工對加工效率之影響 55
4.4覆層加工對表面形貌之影響 58
5.結論與未來展望 75
5.1結論 75
5.2未來展望 76
參考文獻 77

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