数控加工实时数据的三维色谱图分析方法研究

During CNC machining process of complicated curved surface, the command and feedback signals in every control cycle are recorded in realtime. A digital tool location surface (TLS) can be reconstructed from the recorded axes position. By coloring each of tool point on the surface with the value of the signal at the same record cycle of the point, a chromatography of the signal is formed. With such a chromatography, the signals collected in time sequence during the control process are mapped onto the three-dimensional TLS. Under this way it becomes possible to measure the signals’ discontinuity along the TLS. The geometrical model of the TLS can be reconstructed by reorganizing the tool location points from the recorded data. In this proposal, a metric method of the signals’ discontinuity on the 3D TLS will be studied and the mapping relationship between the signals’ discontinuity and the geometrical features on the machined surface will be explored to discover the law of impaction on the physical shaping process activated by the signal’s changing. The control algorithm’s performance on keeping consistency between two adjacent paths will be studied based on the distribution of the feedrate’s discontinuity on the TLS. Based on the tracking errors of all motion axes, the deviation error along the normal vector at the tool location point from command position to feedback position will be calculated to study an approximation method of profile tolerance error, which can be used in the machining process to do realtime evaluation of the surface’s quality. Based on the statistical distribution of the spindle’s load current along the program’s blocks, optimization method of the machining parameters for coarse milling will be studied to improve the machining efficiency.

在数控曲面加工过程中，实时记录每一个控制周期的指令和反馈信号，从其中的坐标位置重构刀位点数字曲面。对曲面上每一点，用同周期的信号值大小着色，形成该信号的三维色谱图。将控制过程中的时序信号，映射到三维的刀位点数字曲面上，藉此可实现过程信号在空间曲面连续程度的数学度量。基于实时记录的刀位点坐标重构零件的刀位点曲面几何模型，研究指令信号和反馈信号在三维刀位点曲面上的连续性的度量方法，探索信号的空间不连续度与加工表面几何形状不连续特征间的映射关系，揭示信号变化对物理成形过程的作用规律。基于合成速度在刀位曲面的不连续分布特征，研究控制算法在相邻轨迹一致性上的控制特性；基于各轴跟随误差，计算编码器实测刀位点相对指令刀位点的法向偏差，研究基于刀位点法向跟随偏差估算实际曲面轮廓误差的方法，实现曲面加工质量的实时评价；基于主轴电流信号在各程序段间的统计分布，研究粗加工的工艺参数优化方法，提高加工效率。

在数控加工制造中，实时记录每一个控制周期的指令与反馈信号，为零件加工过程全数字化数据溯源提供基础。本项目在此基础上，研究了数控加工实时数据的三维色谱图分析方法。通过对实时加工刀位点进行疏化和三角片化，构造了刀位点空间几何模型，用于加工指标信号的色谱显示和不连续度分析。建立了指标信号与零件加工表面的映射关系，为进一步评价数控系统速度规划和运动控制算法的性能提供有效途径。.建立了基于机床编码器反馈信号的曲面零件轮廓误差近似计算模型。该模型利用采集的机床编码器或光栅尺在每个控制周期的反馈信号，与指令插补信号构建的三角片曲面模型进行对比分析，并利用三坐标测量机对估算结果进行标定，得到实际曲面轮廓误差的估算结果。在数控加工指令域上，研究了机床主轴电流及其衍生信号的分析方法；通过定位电流及其衍生信号在三维色谱图上的不连续特征，建立电流及其衍生信号的均衡优化模型，实现腔槽类零件粗铣加工的工艺参数优化。.在三维色谱分析和速度规划和控制算法评价研究的基础上，开发了用于三维曲面加工分析和优化软件（iSurfine），在复杂曲面、模具等高精度加工应用中有效提高了零件的加工表面质量。在基于主轴电流及其衍生信号连续性的粗加工工艺参数优化方法研究的基础上，开发了用于腔槽类零件粗铣加工的工艺参数优化软件（Afo-Milling）。针对不同的加工对象，能够提升5%~30%的加工效率。两款软件目前成为“华中8型”数控系统推广应用的配套软件，对提高零件加工质量和加工效率具有重要的意义。