机床床身结构综合优化设计技术

Comprehensive optimization technique for machine tool bed structure

针对目前常用的内部布置加筋板的箱型床身结构,提出一种同时考虑床身结构的动静态刚度和经济性的综合优化技术。由于床身结构的动静态刚度和质量与支撑垫铁的位置、内部加强筋板布局以及各构件的厚度尺寸有关,提出的综合优化设计技术包括以下3个层次:首先以结构的最大静动态刚度最优为设计目标,对床身结构的垫铁位置进行优化;其次在多工况情况下,以结构的最大静态刚度最优为设计目标,对床身结构的内部加筋板布局进行优化;最后以结构质量最小,以结构的动静态刚度为约束条件,对构件的尺寸进行优化。优化结构表明,采用提出的设计方法,在床身结构质量减小24.48%的情况下,结构的一阶固有频率提高7.83%,结构的导轨静变形有所变差,中间段偏离零线0.5μm左右,但并不影响加工精度,可通过预修正来抵消变形,说明了提出的设计方法的有效性。

Take a typical type of box bed structure which contains stiffener as an example,a comprehensive optimization process will be established to take both static and dynamic stiffness and economy into consideration. Due to the fact that the static and dynamic stiffness is related to location of pad irons,layout of stiffeners and thickness of components,the comprehensive optimization process includes three different steps. The location of pad irons will be optimized first,whose objective is to maximize the maximum static and dynamic stiffness. Then the layout of stiffeners will be selected as an optimization object to get the same objective as first step under multiple loading conditions. Finally,the thickness of components will be optimized to minimize mass of the machine tool bed with constrain of the static and dynamic stiffness of the bed. The result shows that the mass of the machine tool bed decreases by 24. 48% and first order natural frequency of the bed increases 7. 83%. In spite of the fact that static deformation of guide which can be compensated increases to about 0. 5 μm,the results indicate this comprehensive optimization process mentioned in this dissertation is effective.