G型结构立式镗铣机床位置刚度数值模拟与试验

研究G型结构立式镗铣机床工作空间位置刚度随工作空间体积变化规律.根据联接单元特征,将主轴轴承、线性导轨及丝杠等动联接采用弹簧等效;建立整机静刚度预测实体模型;结合有限元方法数值模拟工作台、主轴及整机X、Y、Z误差敏感方向工作空间的位置刚度分布,以离散点试验验证研究立式镗铣机床X、Y、Z三向的静刚度.结果表明:机床离散点试验获得的静刚度数据与数值计算结果最大误差为8.7%,主轴三向静刚度随Z轴行程增加而非线性减小,工作台X、Y轴中间位置三向静刚度最大,呈抛物状向外递减,机床整机静刚度同工作台静刚度呈相似分布规律.数值模拟数据为G型精密机床结构设计及位置误差补偿提供了理论基础.

Experiment and simulation of position stiffness of a G-type frame structure vertical machine center

he luffing system of crawler crane, an important part of whole crane, has enough capacity to realize the boom luffing. Analyzing the characteristics of components, the mechanical model of luffing system and the multi\|objective optimization model are built. Using the method of physical programming, an integrated optimization evaluation function is defined with preference functions based on limit loads of components. A multi\|objective chaotic genetic algorithm, updating solution set with Pareto domination and elitist strategy to retain the optimum solution set, and the chaotic local search to avoid premature convergence, is designed. Numerical example shows that the method can efficiently optimize geometrical relations of components to reduce forces and significantly guide the overall parameter design of crawler crane.