綜合加工機動態特性與結構強化之研究

Modal Testing, Analysis and Improvement on the Structure of a Machining Center

劉勝安(Sheng-An Liu) ； 施習中(Si-Chung Shih)

《大葉學報》 10卷1期 (2001/06) Pp. 61-67

https://doi.org/10.7119/JDYU.200106.0061

摘要

現今之VC-80型綜合加工機於主軸轉速約80-85 Hz（4800-5100 rpm）時機體產生振動過大（共振）之現象，為使該機體之主軸於高速運轉時不會產生共振之現象，該機體結構之動態剛性需予強化。本研究即針對該機之機體進行結構設計改善。在具體之做法上為首先對該機之機體進行實際之振動模態測試，以獲得各固有頻率與對應之振型。另外則以該機各組成單體與整機之設計圖為依據以NASTRAN建立有限元素模式，並加以計算分析。經由實測與分析所得各結果之比較，修正獲得正確之模式，並以該模式為基礎，設定相關之設計變數與改善目標，並進行設計之改善。而研究之成果除解決了該機前述之缺失外，同時亦闡明了有限元素分析之應用於加工機機體設計上之有效性與必要性。

關鍵字

固有振型 ； 模態測試與分析 ； 最佳化設計

並列摘要

This study endeavors to resolve a problem in which significant vibration (resonancy) occurs in a current VC-80 machining center at a spindle speed of 80-85 Hz (4800-5100 rpm). First, actual model testings under free vibration conditions are implemented on the overall structure and individual parts to obtain the natural frequencies and the corresponding mode shapes of the vibrations. Then, finite element models based on design drawings are constructed and subjected to analysis using NASTRAN. The results from actual experiments and finite element analyses are compared in terms of weights, frequencies, and mode shapes. When an accurate finite element model of the overall structure is obtained, improvement on its dynamic stiffness based on an optimization procedure is then performed. The results indicate that the first resonant frequency is increased more than to 100 Hz (6000 rpm). This study also demonstrates the effectiveness and neccesity of using finite element analysis in the design of a machining structure.

並列關鍵字

modal testing and analysis ； finite element analysis ； optimization