超跨距横梁Z向导轨面起拱曲线设计与优化

针对数控重型龙门铣床超跨距横梁由于跨度大、质量大,安装完毕后由于重力和溜板滑枕作用力会向下弯曲,其中Z向导轨面的最大挠度可达到1 mm,严重影响加工精度的问题,采用对导轨面预起拱的方法来补偿横梁变形对加工精度的影响.首先,采用有限元方法分析超跨距横梁实际工作时的变形,并采用多项式对溜板滑枕在各位置时横梁Z向导轨面的变形进行拟合;充分考虑由于溜板跨度带来的2条变形曲线对起拱曲线的影响,提出了基于这2条变形曲线进行起拱曲线设计和优化的方法.分析以往各种起拱曲线对刀尖点变形的影响,结果表明:所提出的优化方法较以往的起拱方法更能有效降低横梁变形对机床精度的影响.

Design and Optimization of the Z-guided Face Camber Curve of Super-span Cross-rail

As super-span cross-rail of NC heavy-duty planer type milling machine tool has a super span and heavy mass,it will bend down after being installed with a heavy mass and the force caused by bottom slid and quill. The largest deformation of Z-guided face attains 1 mm,which seriously influences the machining accuracy. Machining an arch camber in advance is used to compensate for the influence caused by deformation of the cross-rail. Finite element method is used to analyze the deformation of the super-span cross-rail when working. Multinomial is used to fit the deformation curve based on deformation of the Z-guided face of the cross-rail when the bottom slid and quill is at any position. This paper takes into consideration the impact on camber curve as the bottom slid's span brings about two deformation curves. A method based on the two deformation curves is put forward to design and optimize the camber curve. By comparing various camber curves' effects on the deformation of the milling head,results show that the optimization method can effectively reduce the influence of cross-rail's deformation on the machine tool's accuracy.