一種應用於微細線張力控制的氣體式阻尼器設計研究
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2022
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Abstract
本研究旨在開發一種「氣體式阻尼器」，應用於微細線張力控制的場域，以獲致高穩定性的微細線切割放電加工的技術。氣體式阻尼器設計包含一密閉式容器及送線軸與送線線圈，送線軸端部設計一圓盤，氣體輸入密閉式容器並包覆圓盤，透由氣體壓力均勻地施壓於圓盤，使圓盤轉動時，產生阻尼效果，抵抗送線軸的轉動。在定速收線條件下，20 μm的微細銅線線張力大小可視氣體對送線軸圓盤施加壓力的大小，以調整適當線張力，提升微細線切割放電加工的精度。實驗結果顯示，在0.16 kg/cm2的氣體壓力下，微細線張力值為43.2 g，進行微細銅線切割實驗，平均溝槽最小標準差可達0.08 μm。實驗以超微粒碳化鎢為材料，對蝸型微結構(Spiral microstructure)及66微錐狀探針陣列(Micro tapered needles array)進行切割驗證，發現以「氣體式阻尼器」控制的細線張力，能穩定且長時間地加工出具高一致性槽寬的蝸形微結構，表面粗糙度可達Ra 0.1 μm，最大蝸型線寬度與最小蝸型線寬度相差小於1 μm，且最大槽寬與最小槽寬也相差小於1 μm；在微錐柱陣列方面，切割的錐針深寬比可達1:40，微錐柱特徵尺寸標準差小於1.5 μm。證實本研究所開發「氣體式阻尼器」線張力控制技術具穩定線極走線的效果，能抑制微細線極晃動與偏擺，提升微細結構加工的筆直度及改善表面粗糙度與切割效能。本製程所需成本低，容易控制，此項成果著實能貢獻於精微加工技術。
The purpose of this study is to develop a pneumatic damper applied to the field of microwire tension control to obtain highly stable microwire electrical discharge machining technology. The designed pneumatic damper consists of an airtight container, a wire-feeding shaft and a wire-feeding bobbin. A disc is designed at the end of the shaft, and the air is fed into a closed container and surround the disc. The air pressure is evenly applied to the disc, so that when the disc rotates, a damping effect is produced to resist the rotation of the wire shaft. Under the condition of constant speed take-up, the tension of 20 μm micro brass wire can be determined by the pressure exerted by the air on the shaft-end disc, so as to adjust the appropriate wire tension, improving the accuracy of micro w-EDM. Experimental results show that the micro-wire tension is 43.2 g under the air pressure of 0.16 kg/cm2, creating the minimum standard deviation of the average slot-width can reach 0.08 μm. A spiral microstructure and 6x6 micro tapered needles array are machined to evaluate the feasibility of the proposed technology. It is found that wire tension controlled by pneumatic damper can steady produce spiral microstructure of high-consistent groove width under a long-tern machining. The surface roughness can reach to Ra 0.1 μm and the differences between the maximum and minimum spiral-width and the slot-width are all less than 1 μm. In terms of micro tapered needles array, an aspect-ratio of 1:40 can be achieved and the standard deviation of feature size of the micro tapered needle array is less than 1.5 μm. It is confirmed that the developed wire tension control technology with"pneumatic damper" has the effect of stabilizing the microwire electrode in this study. It can suppress the swaying errors of the microwire, improving the form accuracy of the microstructure and the surface roughness, and then increasing the cutting performance. The proposed technology is low cost and easy to control and really contribute to the micromachining technology.
The purpose of this study is to develop a pneumatic damper applied to the field of microwire tension control to obtain highly stable microwire electrical discharge machining technology. The designed pneumatic damper consists of an airtight container, a wire-feeding shaft and a wire-feeding bobbin. A disc is designed at the end of the shaft, and the air is fed into a closed container and surround the disc. The air pressure is evenly applied to the disc, so that when the disc rotates, a damping effect is produced to resist the rotation of the wire shaft. Under the condition of constant speed take-up, the tension of 20 μm micro brass wire can be determined by the pressure exerted by the air on the shaft-end disc, so as to adjust the appropriate wire tension, improving the accuracy of micro w-EDM. Experimental results show that the micro-wire tension is 43.2 g under the air pressure of 0.16 kg/cm2, creating the minimum standard deviation of the average slot-width can reach 0.08 μm. A spiral microstructure and 6x6 micro tapered needles array are machined to evaluate the feasibility of the proposed technology. It is found that wire tension controlled by pneumatic damper can steady produce spiral microstructure of high-consistent groove width under a long-tern machining. The surface roughness can reach to Ra 0.1 μm and the differences between the maximum and minimum spiral-width and the slot-width are all less than 1 μm. In terms of micro tapered needles array, an aspect-ratio of 1:40 can be achieved and the standard deviation of feature size of the micro tapered needle array is less than 1.5 μm. It is confirmed that the developed wire tension control technology with"pneumatic damper" has the effect of stabilizing the microwire electrode in this study. It can suppress the swaying errors of the microwire, improving the form accuracy of the microstructure and the surface roughness, and then increasing the cutting performance. The proposed technology is low cost and easy to control and really contribute to the micromachining technology.
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Keywords
氣體式阻尼器, 線張力, 蝸型微結構, 微錐狀探針陣列, Pneumatic damper, microwire tension, spiral microstructure, micro tapered needles array