萬能圓筒CNC磨床機之疲勞分析與優化設計

本論文針對萬能圓筒CNC內外圓磨床機之結構設計需要達到高穩定性、高剛性及避免發生共振，以降低加工物件的誤差值為目的。研究使用有限元素分析軟體ABAQUS對磨床工具機作下列幾項數值模擬分析1. 結構剛性分析:機台在磨削外力負載下，對整機結構所造成的應力分布情形與變形量大小。2. 優化設計:將零組件分析結果進行修正，藉由參數設定找出符合限制條件下最佳之材料分佈，將結構去除多餘的材料以降低成本。3. 模態分析:分析磨床機之自然頻率以避免與振動頻率產生共振。4. 疲勞損壞分析:針對外徑傳動主軸的受力狀態，進行應力分析及使用副程式FE-SAFE分析疲勞壽命。實驗部分為量測自然頻率值：利用加速度規與敲擊槌互相搭配使用擷取頻率響應函數數值，將敲擊所得到的結果傳送至頻譜分析儀作資料處理，最後匯入模態分析軟體(ME’scope)建立模態振型。研究結果顯示結構剛性分析最大等效應力值為0.67(Mpa)，平均位移量為0.92(μm)，依據虎克彈性定律算出機台結構靜剛性為63.3(MNm-1)，等效應力結果低於材料FC300的降伏應力300(Mpa)，推論磨床機結構不會因為機台加工磨削而產生永久之變形。最佳化設計經由優化前後之比較，均有效的減少應力極值，下降幅度最大約為5.43%。而模態分析與實驗比對後，零件的平均誤差百分比為10%以內；整機結構誤差百分比為3%以下，可知分析結果與實際敲擊結果的數據具有良好相符性，在結構設計階段具有其參考價值。最後外徑傳動主軸於動態分析結果內，最大等效應力值為231.3(Mpa)低於材料S45C降伏強度250(Mpa)，故不會產生變形；而疲勞壽命約為119,3988次，估算成實際壽命約可以使用六十年以上，以結構強度觀點而言，主軸擁有良好的高破壞強度係屬安全設計。

關鍵字

ABAQUS ；磨床機；靜態剛性；疲勞分析；拓樸優化設計

並列摘要

The purpose of this study is to lower deviation of workpiece by meeting high stability and rigidity to prevent the resonance in producing procedure of the CNC universal cylindrical grinding machine. Using finite element analysis software ABAQUS grinder machine tools for numerical simulation of several analysis for the following 1. Structural rigidity analysis, machine in external grinding load, the stress caused by the distribution and the deformation of the size of the whole structure. 2. Optimized design, the results of the analysis of components is corrected by setting the parameter to identify the best distribution of the material under the conditions comply with the limits, the structure to remove excess material to reduce costs and optimize the results before and after each comparison. 3. Vibration frequency analysis, analysis natural frequencies of grinder machine to avoid resonance. 4. Fatigue damage analysis, we aim on state of the transmission of outer diameter spindle to proceed in stress and fatigue life analysis by FE-SAFE Subroutine. In experiment section. We expect to obtain measured value of natural frequency. First, capturing the value of frequency response function by accelerometer with percussion hammer, and sending value which captured from hammer to spectrum analyzer for data processing. Finally, we import data to modal analysis software (ME’s scope)for establish a modal shape. The study result appears as following, max value of equivalent stress and average amount of displacement in Structural rigidity analysis are 0.67(mpa) and 0.92(μm). Base on the Hooke's law of elasticity we can calculate static structural rigidity of machine is 63.3 (MNm-1). The result is less than equivalent stress yield stress of material FC300 300 (Mpa), so we can find out this grinder machine’s structure will not produce permanent deformation of inference in grinding processing. Optimal design optimization by comparing before and after, effectively reduce stress extreme value, the largest decline of about 5.43%. And modal analysis compared with the experimental, the average error percentage was less than 10% of parts. The whole structure percentage error does not exceed 3%, shows the results of analysis and practical percussion data Conformance with nice, has its reference value in the structural design phase. Finally, the outer diameter of the drive shaft in the dynamic analysis results, maximum stress is 231.3 (Mpa) less than S45C material yield strength 250 (Mpa), therefore, no distortion. The fatigue life of approximately 1,193,988 times, estimates into real life can use more than sixty years, from the viewpoint of structural strength, spindle has a good high breaking strength is designed to be safe.