| 摘要: | 碳化鎢材料因具備高機械強度及硬度而屬於難加工材料，當採用線切割放電加工、燒結法等方式製備微球形工具時，會有表面容易缺陷、高成本、需較長加工時間等問題產生，難以加工出尺寸精度及表面形貌較佳之微球形工具，為了克服前述困難點。本研究採用旋轉工件之方式，並設計出一三板片電極，以及使用一向上噴流式電解液供給治具及旋轉工件之方式，進行微電化學加工製備微球形工具，並探討工作電壓、脈衝休止時間、電解液流率及工件轉速等不同加工參數對微球形工具整體形貌、最大徑、最小徑、直徑比值、消耗長等品質特性之影響。而本研究亦選擇尺寸及形貌較適合之微球形工具，進行超音波輔助微球形工具電化學放電玻璃鑽孔測試，以驗證微球形工具之實用性。而本研究最後以較佳參數組合製備之微球形工具，進行電化學精修微球形工具測試，並計算圓度，使得微球形工具前端能更接近球形形貌。
實驗結果顯示，以旋轉工件之加工方式，能使工件徑向方向所受到之電化學加工影響分布均勻，進而使微球形工具之表面形貌較均勻。當採用本研究較佳之參數組合，即工作電壓9V、脈衝休止時間40μs、電解液流率
1800ml/min及工件轉速300rpm時，可得到較佳微球形工具尺寸為最大徑307μm、最小徑186μm、直徑比值1.649及消耗長1276μm，並能有效改善微球形工具整體形貌，且經電化學精修微球形工具測試後之圓度降為1.200，使得微球形工具前端形貌能更加接近球狀。;The tungsten carbide material is a difficult-to-machine material due to its high mechanical strength and hardness. When wire electrical discharge machining and sintering are used to prepare micro spherical tools, there will be problems such as easy surface defects, high cost, and long processing time, making it difficult to produce micro spherical tools with good dimensional accuracy and surface morphology. To overcome the said difficulties, this study used a rotating workpiece and designed a three-plate electrode, as well as an upward jet electrolyte supply system and rotating workpiece, to prepare micro spherical tools through micro electrochemical machining. The effects of different machining parameters such as working voltage, pulse off time, electrolyte flow rate, and workpiece rotation speed on the quality characteristics of the micro spherical tool, including overall morphology, maximum diameter, minimum diameter, diameter ratio, and length consumption, are investigated. This study also selected micro spherical tools with suitable sizes and morphologies for ultrasonic-assisted electrochemical discharge glass drilling tests to verify the practicality of the micro spherical tools. Finally, this study used a micro spherical tool prepared with an optimal parameter combination to test electrochemical finishing of the micro spherical tool, and calculated its roundness, so that the tip of the micro spherical tool could further approximate a spherical morphology.
Experimental results show that rotating the workpiece during machining can ensure an uniform distribution of the electrochemical machining effect in the radial direction, resulting in a relatively uniform surface morphology of the micro spherical tool. When the optimal parameter combination of this study was used, such as working voltage of 9V, pulse-off time of 40μs, electrolyte flow rate of 1800ml/min, and workpiece rotation speed of 300rpm, the optimal micro spherical tool dimensions were obtained, maximum diameter of 307μm, minimum diameter of 186μm, diameter ratio of 1.649, and length consumption of 1276μm. The overall morphology of the micro spherical tool was improved effectively, and after electrochemical finishing, the roundness of the micro spherical tool decreased to 1.200, making the tip morphology of the micro spherical tool closer to a sphere. |
