放電加工液中添加粉末對放電波形的探討及其加工影響

The effect of EDM waveform of Powder Mixed Dielectric Electrodischarge Machining Characteristics

蔡清展(Ching-Chan Tsai)

指導教授 ： 蔡曜陽

國立臺灣大學/工學院/機械工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.02955

摘要

粉末放電加工(PMD-EDM)能有效降低放電加工的表面粗糙度，不需
要二次拋光加工，能節省時間及成本，而且具加工表面改質的效果。應用在模具方面，可以製造出光電模具所需的大面積具有光澤的加工表面，乃相當具有潛力的加工技術;但目前加工機制僅知添加適當濃度金屬粉末可有效放電分散但為何粉末可有此作用仍尚未解明。
本研究將藉由量測電壓、電流波形變化與粉末聚集狀態現象之同步
觀察來探討介電液中添加粉末時之放電波形之變化及其對加工特性的影響。研究首先觀察實驗中選用不同粉末材料量測可放電間隙範圍，然後進行觀察兩極間的電流、電壓波形同步搭配粉末聚集狀態情形。根據所得到的結果能瞭解電壓、電流波形變化與粉末聚集狀態的情形之間的關係，然後觀察不同粉末與粉末濃度對放電波形的影響，並進一步分析探討粉末濃度對於加工特性的影響，期待詮釋不同材料性質其加工特性結果不同的原因，提供粉末放電加工製程應用的參考。
研究結果顯示，除了添加氧化鋁粉末外，放電延遲時間會變短波形
會有充電時間內跳電之釋放電流（breakdown during delay time）現象，並且受到粉末材料、粉末濃度的影響，其充電時間與釋放之數目都不一樣，研究中利用上述現象解明不同粉末材料不同濃度對表面粗糙度及材料移除率的影響。

關鍵字

放電加工 ； 放電加工液中添加粉末 ； 放電波形 ； 粉末聚集行為

並列摘要

PMD-EDM, which has a lot of efficiency in reducing the surface
roughness produced by EDM, not only can save much time and money but
also produce very fine finish surfaces without second time polishing. It is a
very potential technology because of its ability of making large burnished
work surfaces when applied to Electro-Optical dies. However, the work
mechanism of PMD-EDM is not fully understood. By synchronizing the
powder behavior and the changes of voltage, current, and waveform, this
study will discuss the influence on work mechanism and waveform
characteristic when adding powder to dielectric fluid. It could be observed
that the range of discharged gap of different powder materials first, and the
current, voltage, waveform synchronizing the powder behavior. According to
the result, the relationship of he current, voltage, waveform synchronizing the
powder behavior can be understood.
The result of the study showed that the discharged waveform would have
the affair of releasing current, which would be influenced by different powder
material and concentration except for Al2O3. Using above phenomenon in the
study, the influence of different powder material and concentration on surface
roughness and the rate of removal should be known.

並列關鍵字

EDM ； Powder mixed dielectric ； waveform ； Powder behavior

參考文獻

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