- 學位論文
滾珠螺桿之螺帽應變分析及動態量測系統建立
The Strain Analysis and Dynamic Measuring System Established for the Nut of a Ball Screw
摘要
本研究中利用有限元素法建立滾珠螺帽3D模型，並考量在內螺紋軌道上不同受力型式對於螺帽表面應變之影響，藉以分析在具預壓作用之滾珠螺桿，在不同軸向負荷與轉速條件下所造成之滾珠對螺帽軌道受力方向變化，及慣性力與軸向力對螺帽表面應變量變化。利用應變規黏貼於螺帽表面上建立應變即時量測系統來做螺帽靜態應變量測與螺帽動態應變量測。其中靜態應變量測主要是將滾珠螺桿利用剛性試驗機來做拉伸與壓縮使螺桿與螺帽產生受力與變形之情形，得到軸向力與應變變化曲線圖，並與有限元素模型分析與動態應變量測結果做比較，發現模型分析與實驗量測結果相互印證良好，並藉此建立起軸向力與應變量之資料庫參數。研究結果顯示當軸向負荷與預壓力之相互作用造成滾珠與軌道接觸方向的改變，也影響表面應變量的變化，並造成螺帽表面應變量呈現兩段斜率變化的情形產生。本分析方法之建立可藉由外部應變量測得到內部滾珠與軌道之受力、剛性動態變化與預壓變化等參數。
並列摘要
A three dimension analyzing model was built by the use of the finite element method in this research. The applied direction of normal forces on the inner raceways were also considered to study the effect for the strain on the surface of nut. These were used to analyze strains with considering several applied directions of forces formed by the axial load and operating at different rotational speed. This experiment used the strain gages stuck on the surface of nut to establish the real-time strain measuring system and the static strain and dynamic strain were measured by the system. The static strain of nuts was optioned by the rigid testing machine operated at tension and compression on the screw and the nut was fixed on the holder. This experiment also got the axial force and strain curve to compare with the result of dynamic strain measurement and the model analysis of finite element to establish the database of axial force and strain. From the result, the applied axial load and preload are varied the contact directions between ball and raceway when the axial load lower and higher than the preload, and make two slopes occurred in the experiment result , This affects the varying of the surface strain. The analysis method can be established by measuring strain on the surface of the nut to get of strains forces existed between ball and raceway in a ball screw, and variations of dynamic stiffness and preload.