臺灣博碩士論文加值系統

摘要
典型的加工機運作時的訊號包含了如週期性的滾珠軸承訊號，暫態性的瞬間刀刃的損壞與顫振訊號，還有背景雜訊，在加工過程中偵測這些訊號即時的出現，並且萃取出與時間相關且有意義的訊號有相當大的益處和重要性，因為這是機台潛在的缺陷和產品品質下降的先兆。
本文目標使用麥克風量測三軸CNC工具機銑削鋁合金時的聲音，並利用小波轉換及獨立成分分析分離出對應轉速暫態性的訊號，利用快速傅立葉轉換搭配主軸轉速頻率及刀刃撞擊頻率，並使用主軸負載電流作為顫振出現的佐證，辨識出是否出現發生顫振的頻率。
實驗的結果，能夠從頻譜圖中判斷是否有顫振發生，並且量測表面粗糙度當作基準，顫振發生造成表面產生振紋使粗糙度升高，此機制判斷顫振發生的轉速與否與造成表面粗糙度高低之對應轉速互相吻合。


關鍵字:CNC工具機、銑削顫振、小波轉換、獨立成分分析

Abstract
Typical signals acquired from machine tool involves periodic signal, transient signal and background noise. Transient signal such as cutter breakage and chatter is the issue that leads to deterioration of the product quality. Thus, detecting these signals with considerable and extracting meaningful time-series signal promptly are benefit and significant for research.
In this study, a microphone was used to sense the sound during a 3-axis CNC milling aluminum alloy. The Wavelet Transform and Independent Component Analysis were applied to decompose acquired signal with the aim to extract the chatter signal from sensed signals. The frequency apart from spindle speed and tooth passing frequencies was regarded as the phenomena of chattering. Furthermore, spindle loading current was used as the other evident for judging the onset of chatter.
Experimental results show that the frequency spectrum can be used as the judgement for whether chatter occur or not. Surface roughness is chosen as a benchmark, since chatter lead to high surface roughness. The judgement of chatter occurrence match the variation of the surface roughness.


Keywords: CNC machine tool, Milling chattering, Wavelet transform, Independent component analysis

目錄
摘要 I
Abstract II
誌謝 III
目錄 IV
圖目錄 VII
表目錄 XII
第一章 緒論 1
1-1研究背景與動機 1
1-2前言 2
1-3文獻回顧 2
1-4 論文架構 4
第二章 基礎理論 6
2-1銑削加工原理 6
2-2表面粗糙度 9
2-3訊號分析方法 12
2-3-1小波轉換與傅立葉轉換 12
2-3-2獨立成分分析(Independent Component Analysis,ICA) 16
第三章、實驗目的與架設 22
3-1實驗目的 22
3-2實驗機台架設 22
3-2-1本實驗所使用之CNC加工機 22
3-3量測儀器 24
3-3-1頻譜分析儀 24
3-3-2 表面粗度儀 25
3-3-3 PCB 電容式陣列麥克風 27
3-4切削工件材料鋁合金6061 28
3-5電流計DNM-844-50A 28
3-6實驗流程 29
第四章、實驗結果與分析 31
4-1模擬訊號實驗 31
4-2實際振動噪音分析 34
4-2-1切寬3mm切深1mm 36
4-2-2切寬3mm切深2mm 51
4-2-3切寬3mm切深3mm 58
第五章 研究成果與未來展望 64
5.1研究成果 64
5.2未來展望 66
參考文獻 67
附錄A 量測切削聲音步驟 69
附錄B PCA(Principle Component Analysis)流程 73

參考文獻
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