大型薄壁件多点定位的初始布局优化算法研究

Initial Distribution Optimization for Multi-Point Location of Large Thin-Walled Components

为了抑制大型薄壁件加工过程中传统"N-2-1"定位原理的支承/定位能力局部失效的现象,以满足工件夹紧力和外形定位精度为目标,并基于支承/定位资源约束,提出了跟随加工区域布置定位点的"X-2-1"多点支承/定位方法,该方法不仅能保证工件加工过程中的夹持可靠性,而且能实现对工件不同加工区域定位误差有针对性的重点防控。实验结果表明:使用该方法计算得到的工件最大定位误差小于0.2mm,远远优于传统均布支承/定位点在相同实验条件下实验件0.8mm的最大定位误差,从而抑制了工件外形定位误差对加工质量的扰动。提出的支承/定位点初始布局方案可为进一步的全局优化,并以此控制工件加工变形、提高工艺系统刚度,最终改善加工质量奠定基础。

To restrain the dynamic change of effective locators in the manufacturing process of large thin-walled components,a new ＂X-2-1＂locating method is proposed to distribute the location/support points following machining region,with the goal to meet the requirements for the clamping force,positioning accuracy and maximum support capacity.This method can ensure reliable clamping in the machining process of workpieces,and control positioning error in different machining regions.Simulation and experiment show that the maximum positioning error is 0.2mm,much better than that obtained when twenty location/support points are distributed evenly over the whole support area of a workpiece. The improvement suppresses the perturbations of clamping deformation to machining quality.Furthermore,the optimization result of initial distribution of location/support points provides a foundation for a further global optimization of multi-point location distribution of large thin-walled components so as to increase process system＇s stiffness,decrease machining distortion,and improve machining quality.