考虑模态特性的高速机床进给系统刚度匹配研究

Stiffness Matching Design for Feed System of High-Speed Machine Tool Considering Modal Characteristics

为了得到进给系统的最优动态特性,建立了进给系统的动力学模型。采用有限元法对高速机床进给系统的部件与结合面进行刚度设计,通过分析进给系统的振动形式,找出了在各种因素下系统模态参数的变化规律,以工作台的结构设计为例,进行了合理的刚度匹配。进给系统在低频段沿进给方向振动,最显著的影响因素是工作台的质量、丝杠-螺母副接触刚度、轴承副接触刚度和丝杠自身的拉压刚度,当系统沿垂直于工作台的方向振动时,受导轨-滑块结合面刚度的影响较大。在不同导轨、滑块跨距组合参数下,对系统模态的特性变化规律进行了分析,当滑块跨距为400mm、导轨跨距为300mm时,系统模态为最优分布。研究表明,该刚度匹配设计方法可使工作台的质量减小10%,进给系统的1阶固有频率提高9%,从而验证了该方法的准确性。

To obtain the optimum dynamic characteristics of feed system, a dynamic model of the system is set up with finite element method to carry out the matching design of components and joint interfaces for high-speed machine tool. Analyzing the vibrating mode of the feed system, the changing rule of system mode parameters due to various factors is revealed. The optimization of the inner table structure is taken as an example to illustrate the matching design. When the system vibrates in feeding direction, the important affecting factors are table mass, screw-nut joint stiffness, bearing stiffness and screw stiffness itself, but when the system vibrates in direction normal to the table, the guideway joint interface stiffness dominates. Investigating the changing modes in different corporations of guideway spans and slides, the optimum result is found, the slide span of 400 mm and guideway span of 300 mm. The table mass can be reduced by 10% and the first-order frequency of the system increased by 9%.