基于元结构和框架优选的数控机床床身结构动态设计研究

RESEARCH OF DYNAMIC DESIGN OF MACHINE TOOLS BED STRUCTURES BASED ON OPTIMIZATION UNIT STRUCTURES AND FRAMES

提出数控机床大件结构设计元结构和基本框架的概念 ,把由床身筋板围成的栅格称为筋格 ,床身的宏观构形为基本框架。筋格的动态特性直接影响机床床身的动态特性。分别以筋格各边长、板厚和清砂孔径为设计变量 ,以筋格的固有频率为优化目标 ,进行有限元动态设计 ,得到相应的筋格的基频随设计变量变化的曲线图 ;通过有限元分析 ,发现当床身的高度与宽度接近时 ,床身的动态特性较好。用有限元分析法对简化的床身结构动态特性进行研究 ,总结出对数控机床床身设计具有普遍指导意义的规律 。

The concepts of unit structures and basic frames for design of NC machine tools main components are given. The unit of grids formed by the rib walls of machine tools bed is named rib box, and the shape of machine tools bed is named basic frame. The dynamic characteristic of rib box directly effects dynamic characteristic of machine tools bed. When optimal aim is the natural frequency of rib box and design variables are respectively the length of rib box edges, the thickness of rib walls and the diameter of sand hole, by FEA, the graphs of the natural frequency of rib box can be got correspondingly. By FEA, it is found that when the height of bed is closed to the width of bed, the bed has good dynamic characteristic. By studying the dynamic characteristic of simplified machine tools bed with FEA, some useful laws in respect of dynamic optimal design of machine tools bed structures are obtained, and these laws can be used in primary design of NC machine tools bed structures.