- 學位論文
多功能複合磨床整機之模態參數因底座使用不同材料所產生差異之研究
Study on Discrepancy of Modal Parameters of Entire Universal Grinder by Using Different Material in Base
摘要
在組成工具機的許多零組件中，底座是非常重要的一個元件，它不但要支撐所有其他零組件的重量，加工過程產生的切削力也由底座一併承受。本研究的標的物是兩台多功能複合加工研磨機，因使用目的略有不同，所以兩台磨床的結構十分相似，主要的不同點在於其中一台的底座採用鑄鐵材料，而另外一台底座採用樹脂礦物澆鑄而成。因加工特性使然，本研究著重在於，當結構幾乎相似的情況之下，不同材料所導致磨床整機模態參數之差異。實驗結果顯示，在單對底座測試時，樹脂礦物底座確顯出其低頻吸振能力優於金屬鑄件底座的特性，此外，在討論的頻率範圍內，樹脂礦物底座發生共振的機會也比較低。在整機測試方面，因為可能的結構缺陷存在，最低模態的自然頻率兩者幾無差異，但在較低頻範圍(小於125 Hz，相對於主要激振源砂輪的轉速約 7500 rpm)從阻尼比的差異而言，樹脂礦物機台具有較佳的抑振能力。此外在整體探討的頻域範圍內，採用樹脂礦物作為底座材料的磨床，其自然頻率模態的數量也較金屬鑄件的磨床為少，因此樹脂礦物的磨床較不易引發共振現象的產生。在模態振型方面的探討，經實驗發現，不管底座的材料是否改變，對於現有的整體結構而言，在前4個模態B柱旋轉工作台上都存在較大的振型，此處是日後改進的重點。最後對於後續研究，本研究對於整機的模態參數，提出了一些改變或者抑止的方法。
並列摘要
In many components that make up the machine, the base is a very important component, it not only to support the weight of all other components, but also the processing of the cutting force generated by the base together. The subject matter of this study is two universal grinders, their application are only slightly different, so the structure of two grinders is very similar, the main difference is that one of the base made by cast iron material and the other is resin mineral. When the grinder processing, the cutting force is very small, therefore, this study ignored the effect of cutting force, and focuses on difference in modal parameter of grinding machine caused by different materials. The experimental results show that in the bases test, resin mineral base does show that its vibration absorption capacity in low-frequency, resin mineral is better than the metal casting base. Moreover, in the interesting range of frequency, the resin mineral base is relatively low opportunities to bring on resonance. In the whole machine test, because the possible structural defects exist, the lowest mode of the natural frequency of the two almost no difference. But in the lower frequency range (less than 125 Hz, relative to the main excitation source, the wheel, its speed about 7500 rpm), from the different damping ratio between them, the resin mineral machine has better anti-vibration ability. In the discussion of modal shape, the experiment found that B-column rotating table of both grinders existing large vibration in first four modes. Hence, the B-column rotating table is the emphasis of further improvement. Finally, for the follow-up study, this study raised some methods for the further research to change or suppress the modal parameter of the whole machine.