五軸工具磨床振動分析模式

今日工具機的研發朝向高精密度，高速切削發展，影響工具機之精密度有很多原因，而其中振動問題一直是疲勞破壞、精密製造過程中需要克服的重要問題。本研究結合有限元素分析及實驗模態分析，對工具機磨床進行模態分析。分析工具機結構自然頻率的方法，傳統是利用理論演算、數學模型等方式進行模擬預測，但對於結構日趨複雜的工具機是無法使用理論解析的方法求得其動態特性。所以現代最主要的應用方法仍為有限元素法。在實驗模態測試部分，本研究使用頻譜分析儀，量測出整機之頻率響應函數圖形，求解工具機整機結構之動態分析；在有限元素分析方面，使用Ansys有限元素分析軟體，進行整機分析，經由模態分析所求得之頻率值與實驗模態動態分析作比對，以驗證Ansys分析結果與實驗值之準確性，並依其差異性進行探討、修模及參數校正。以得到能代表實際結構之等效分析模型。完成這些實驗之後，可以找到機台的自然頻率，當機器運轉時必須避開這些自然頻率，以免造成共振現象。並且針對結構剛性不足之鑄件進行改善，使振動位移降到最低。

關鍵字

有限元素分析；模態分析；工具機磨床；共振

並列摘要

The research combines finite element analysis and experimental model analysis to deal with machine tool analysis grinder. The method of tool structure analysis traditionally is utilizing theoretical algorithm, mathematic model to forecast; however, machine tools which are complicated gradually cannot be to theoretical analysis get dynamic properties. Therefore, main method in the modern times is finite element method. In the part of experimental model analysis, the spectrum analyzer is used to measure function diagram of overall frequency response; in the part of finite element analysis, finite element analysis software Ansys is adopted to get dynamic analysis of whole tool structure. The frequencies from the model analysis validate each other to test the accuracy of experimental result, and the differences are discussed, revised, adjusted. It can be expected that there is an equivalent analytical model for the actual structure. Finally, tool natural frequency was found after these experiments completed. These natural frequencies should not equal to machine frequencies in operation, and resonance can be avoided. Then it reduces vibration by improving structure rigidity.