臺灣大學: 機械工程學研究所蔡曜陽張祐鳴Chang, Yo-MingYo-MingChang2013-04-012018-06-282013-04-012018-06-282010http://ntur.lib.ntu.edu.tw//handle/246246/256315本研究利用高壓空氣取代傳統放電油作為介電流體，可降低加工過程中產生之有害物質，並減少放電加工製程對環境的危害。 為了將氣體導入放電間隙，而自行架設桌上型氣中放電加工機台並設計放電旋轉主軸，主軸旋轉功能可加快消弧動作，且高壓氣體除了能帶走間隙中被熔融之工件材料，還可帶離間隙中被電離之氣體介質，增加恢復絕緣的效率。本研究利用田口方法對於以下放電控制因子如開路電壓、峰值電流、放電持續時間、工作因子、伺服速率比、間隙參考電壓比、氣體壓力與主軸轉速等進行實驗，針對放電加工特性如：材料移除率、電極消耗比及表面粗度值進行變異分析，比較各因子之貢獻率與顯著性。期望瞭解氣體放電加工特性，作為未來產業應用上，氣中放電加工製程的基礎。 實驗結果得到影響材料移除率之顯著因子依貢獻率大小依序為：峰值電流、間隙參考電壓比、空氣壓力、開路電壓及放電持續時間，其最佳化條件為開路電壓400V、峰值電流30A、放電持續時間100us、工作因子0.75、空氣壓力0.5MPa、主軸轉速600rpm、伺服速率比25%及間隙參考電壓比10%，材料移除率可高達23.64mm3/min。影響電極消耗比之顯著因子為間隙電壓、工作因子、峰值電流及電流持續時間，其最佳條件為開路電壓400V、峰值電流20A、放電持續時間50us、工作因子0.75、空氣壓力0.1MPa、主軸轉速1400rpm、伺服速率比75%及間隙電壓30%，其電極消耗比最小可達0.13%。影響表面粗糙度的顯著性因子為工作因子、空氣壓力、峰值電流及放電持續時間，最佳條件為開路電壓400V、峰值電流10A、放電持續時間50us、工作因子0.25、空氣壓力0.1MPa、主軸轉速600rpm、伺服速率比50%及間隙參考電壓比10%，最佳表面粗糙度達5.447um。 氣中放電之電極消耗比特性來自於電弧放電造成工件融渣附著於電極表面而形成保護作用，而電弧放電率越高，形成之保護面積越大。In this research, we used air as dielectric fluid instead of traditional EDM oil, trying to decline toxic substances against environment during manufacturing processes. To lead air into discharge gap, we set up a desktop EDM machine and designed the spindle by ourselves. When the spindle rotates, the discharge arcs will be eliminated rapidly. Besides, air with high pressure can take both ionizations and melting materials away from the gap, leading higher efficiency. The Taguchi Methods was used in this research. The chosen factors are listed in the following: open voltage, peak current, pulse duration, duty factor, servo ratio, reference ratio of gap voltage, air pressure, spindle speed. We compared different machining effects resulted from various factors by analyzing machining characteristics such as material removal rate (MRR), relative electrode wear ratio (REWR) and surface roughness (Ra), hoping to develop the base of Dry EDM The degrees of significant factors influenced MRR from large to small as follows: peak current, reference ratio of gap voltage, air pressure, open voltage, duty factor. The MRR can achieve to 23.64mm3/min under the optimum condition with open voltage of 400V, peak current of 30A, pulse duration of 100us, duty factor of 0.75, air pressure of 0.5MPa, spindle speed of 600rpm, servo ratio of 25%, reference ratio of gap voltage of 10%. Besides, the degrees of significant factors influenced REWR from large to small as follows: reference ratio of gap voltage, duty factor, peak current, duty factor. The REWR can achieve to 0.13% under the optimum condition with open voltage of 400V, peak current of 20A, pulse duration of 50us, duty factor of 0.75, air pressure of 0.1MPa, spindle speed of 1400rpm, servo ratio of 75%, reference ratio of gap voltage of 30%. The degrees of significant factors influenced surface roughness from large to small as follows: duty factor, air pressure, peak current, pulse duration. The Ra can achieve to 5.447 um under the optimum condition with open voltage of 400V, peak current of 10A, pulse duration of 50us, duty factor of 0.25, air pressure of 0.1MPa, spindle speed of 600rpm, servo ratio of 50%, reference ratio of gap voltage of 10%. During Dry EDM, the reason of lower REWR is that the melting workpiece material stuck onto the electrode surface and thus produced a protection layer. The protection layer is formed from arc, and the area of protection layer increase with the arc discharge ratio.3205586 bytesapplication/pdfen-US氣中放電材料移除率電極消耗比田口方法dry edmmaterial removal raterelative electrode wear ratiotaguchi methodthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/256315/1/ntu-99-R96522730-1.pdf