自由曲面侧铣刀具轮廓与轨迹同步优化方法

Simultaneous optimization method for tool contour design and path planning of freeform surface flank milling

针对自由曲面侧铣加工中轨迹规划困难、加工精度难保证等问题,提出了一种自由曲线母线类刀具的外形轮廓设计方法。该方法在优化刀具轮廓的同时,充分考虑了加工过程中的工件精度和刀轴光顺性问题,实现了自由曲线母线类刀具的形状设计和对应侧铣加工轨迹的生成。首先,通过分别定义刀具轮廓母线和刀轴轨迹面实现对刀具形状和侧铣加工轨迹的表达,并由此计算切削行上刀具工件干涉量来评价加工误差,以刀轴轨迹面能量评价刀轴光顺性,建立了基于加工误差和刀轴光顺性的刀具轮廓与加工轨迹的同步优化模型;其次,为实现对同步优化模型的求解,给出了基于序列逼近法的求解策略,以及优化初值中刀轴轨迹面控制参数和刀具轮廓控制参数获取方法;最后,分别通过加工轨迹规划实验和刀具轮廓设计实验,验证了本文算法在在自由曲面四轴侧铣加工刀具轮廓设计与加工轨迹优化中的正确性及有效性。研究成果为提高自由曲面类零件侧铣加工精度、实现侧铣加工刀具轮廓设计及侧铣加工轨迹规划提供了一种有效的方法和手段。

Aiming at the difficulties in toolpath planning and machining accuracy achievement in free-surface flank milling,this paper proposes a method for designing the tool contour of freeform generatrix.While optimizing the tool contour,this method fully considers the workpiece accuracy and tool axis smoothness during machining,thereby realizing the tool contour design and the flank milling path planning.This study first evaluates the machining error by calculating the interference between tool and workpiece on the cutting line after respectively defining the tool contour generatrix and tool axis trajectory surface to express the tool shape and flank milling path.The tool axis smoothness is also evaluated by tool axis trajectory energy,and a simultaneous optimization model of tool contour and machining trajectory based on the machining error and tool axis smoothness is established.Secondly,to solve the simultaneous optimization model,a solution strategy based on the successive approximation method is presented,and the method for acquiring the control parameters of the tool axis trajectory surface and the tool contour control parameters in the initial values are also provided.Finally,the path planning experiment and tool contour design experiment are designed respectively,verifying the correctness and effectiveness of the algorithm in the tool contour design and path optimization for 4-axis flank milling of freeform surface proposed in this paper.This research provides an effective method for both accuracy improvement in flank milling of freeform surface parts and realization of the tool contour design and path planning of flank milling.