复杂曲面高质量加工中的插补算法研究

The high quality machining of complex curved surfaces machined by five axis NC machine tools has become an urgent problem to be solved in the field of numerical control technology. Aiming to solve the problems, such as speed fluctuation and "data starvation", caused by discretizing complex curved surfaces into small program segments, this project carry out the research on interpolation algorithm for high quality machining of complex surface. First of all, we study how to synthesize the smooth Akima spline curve used the micro program segments in order to smooth the processing path. Secondly, the Akima spline curve is controlled by the flexible acceleration and deceleration, and the spatial geometric curves with the speed and acceleration constraints are obtained.Finally, research on the Akima curve real-time lookahead interpolation algorithm to discrete the geometric space curve into the locus of points in sampling period. The project will develop five axis CNC system interpolator using the above theroy.Through the experimental study on machining of complex surface parts, verify the above theory and method can guarantee the machining of complex surface, improve the processing quality. The project aims to reveal the dynamic interaction rules between the interpolation calculation and implementation of precision CNC equipment, form new principle and technology of complex parts of high quality processing. The expected results provides the basic theory and technology of five axis CNC system for complex surface parts and high quality processing.

如何实现五轴联动数控机床对复杂曲面工件的高质量加工已成为当前数控技术领域迫切需要解决的课题。本项目针对将复杂曲面零件离散成微小程序段进行加工存在速度波动和“数据饥饿”等问题，开展面向复杂曲面高质量加工的插补算法研究。首先，研究如何将微小程序段拟合成光滑的Akima样条曲线，以平滑加工路径。其次，对Akima样条曲线进行柔性加减速控制，得到带有速度和加速度约束的空间几何曲线。最后，研究基于前瞻的Akima曲线拟合实时插补算法，将该空间几何曲线离散成采样周期内点的轨迹。应用上述理论，开发五轴联动数控系统插补器。通过对复杂曲面类零件加工的实验研究验证所研究的理论和方法能够保证复杂曲面的加工轮廓，提高加工质量。项目旨在揭示插补计算与数控装备执行精度之间的动态交互规律，形成复杂零件高质量加工的新原理和新技术。预期成果将为五轴联动数控系统复杂曲面零件高质量加工提供基础理论与技术方案。

传统的五轴联动加工无论是工件程序设计还是运动控制依然是基于“准静态”的理想状态，由于未考虑零件实际加工过程中复杂曲面轮廓特征对加工质量的影响，因此，难以满足复杂曲面零件高精密加工要求。为实现五轴联动数控机床对复杂型面零件精密加工，必须首先采用CAD系统进行实体模型设计，再由CAM系统根据加工工艺，将实体模型转换成由NC程序段组成的加工程序，利用数控系统进行加工处理。传统数控加工中将复杂型面零件离散成微小程序段进行插补，存在着拟合精度差、加工程序长、传输负荷大、速度不连续等问题。而且，由于旋转轴的加入，不但加重了运动控制器的运算负担，而且旋转坐标的微小误差就会影响加工精度，因此要求数控系统插补器具有更高的运算效率和精度。本课题研究如何将工件程序中的微小程序段拟合成光滑的样条曲线，即样条曲线拟合方法；对所拟合的样条曲线进行速度规划，得到带有速度和加速度约束的空间几何曲线；对该几何曲线进行插补计算，得到采样周期内离散的点的轨迹；基于上述理论，研发样条曲线插补软件，开展实验验证。课题的开展为复杂曲面零件精密加工技术提供基础和理论，对提升我国在研发精密多轴高速数控系统方面的自主创造能力和创新水平具有重大意义。本课题共发表学术论文9篇，其中国内核心期刊论文4篇，国际会议论文5篇，2件发明专利。