線切割放電加工機放電延遲時間之序列分析

Abstract

放電加工向來被視為具有高度的隨機性，本文之目的在於瞭解看似隨機的現象背後是否有隱藏的規律與特徵。自製放電延遲時間(簡稱Td)擷取電路能夠擷取連續16384發放電Td，在固定進給的情況下逐漸提高進給速率觀察到間歇的放電漸漸轉變為正常的連續放電，由此發覺材料的移除步調與工作台進給並非同步，其中暗藏玄機，細查Td序列，但線索仍然不足，於是再進行無進給加工實驗獲得更多線索幫助推斷極間狀況的動態變化，詳細瞭解了極間渣分佈狀況與二次放電在線切割放電加工中所扮演的角色。實際上連續加工幾乎完全是透過動態分佈的放電渣發生二次放電，渣分佈狀況的穩定性決定了加工狀況的穩定與否，並以顯微鏡觀察放電渣尺寸，足以佐證放電渣對極間狀況影響極大。隨後又研究了正常穩定加工時的微觀穩定性，發現即使宏觀來看放電狀況穩定，但微觀來看變動幅度仍然很大，很可能是進一步改善控制的方向，故於文末基於本研究對連續放電現象更進一步的瞭解提出可能改善微觀穩定性的方法。

Ignition delay time (Td) has been widely used to research the state between wire electrode and workpiece in wire EDM. This paper focus on the effect between neighbor discharge and how these effect cause macro phenomenon. The non-synchronism between stage feed and material remove rate has been researched, and the role debris distribution play in discharge gap has been understood, also explain the self-stable mechanism of continuous discharge. By observing the spectral and autocorrelation function of ignition delay time series particularly, it shows continuous discharge is not fully stochastic process but with some characteristics, the author describe the main characteristics by a diagram. Finally propose a possible strategy to stabilize the micro discharge state.