Model based toolpath correction for ultra-precision machining

在项目的第一个阶段，开发、构建、投入运行和表征了一个交叉工作台，以增加UP光栅铣削的加工动态。通过模态特征模态识别和附加的实时参数识别，实现了轴向结构振动的补偿。除了补偿的结构振动外，多个进给轴之间的相互作用导致的动态路径偏差以及课程组其他项目子系统的影响也降低了表面质量。这可以通过对多个进给轴之间的干扰进行综合补偿来抵消。因此，第二个项目阶段的目标是在考虑其他子系统和切割过程的同时减少整个UP-HPC系统的动态路径偏差。为实现这一目标，将采取三个重点。将现有的补偿方法转移到三个进给轴上，扩展了基于模型的滤波和控制方法，提高了整个系统的鲁棒性。补偿方法的转移需要详细了解三维路径行为，在这种情况下，特别是刀具的轨迹和路径速度。为了描述路径行为，提出了一种直接测试UP光栅铣削路径行为的方法，该方法用特征值量化了路径行为的主要方面。这使得系统地分析需要检查的交互，以及开发在第一个项目阶段创建的子模型之间的互连成为可能。通过这种方式，创建了整个轴系统的模型。为了最小化动态路径偏差，研究了基于扩展模型的滤波和控制方法。这些包括输入整形，以减少轴之间的串扰，以及跟踪控制，以增加动态。这些方法在高性能计算制造中是已知的，需要适应对UP制造精度的高要求。正因为如此，这些方法的底层模型以这样一种方式实现，即它们可以通过使用诸如连续参数识别之类的方法来适应不同的过程状态。在项目阶段的最后一年，考虑到切削过程的振动刺激和附加部件的影响，研究了所开发方法的潜力和局限性。此外，在切削试验中评估了所有开发方法的总体性能。

In the first project phase a cross table was developed, constructed, put into operation and characterized to increase the machining dynamics for UP raster milling. By identifying the modal eigenmodes and an additional real time parameter identification a compensation of structural vibration of the axes was realized. Beside the compensated structural vibrations, the surface quality is reduced by the interactions between multiple feed axes which lead to dynamic path deviations as well as the influences of the subsystems of the other projects of the research group. This can be counteracted by a comprehensive compensation of disturbances between multiple feed axes. Therefore, the goal of the second project phase is to reduce dynamic path deviations of the entire UP-HPC system while taking into account the other subsystems and the cutting process. Three focal points are pursued to reach this goal. The transfer of the existing compensation methods to three feed axes, the extension of model based filter and control methods and the increase of the robustness of the overall system. The transfer of the compensation methods requires a detailed understanding of the three-dimensional path behavior, in this case that is especially the trajectory of the tool and the path velocities. To describe the path behavior a direct test method for the UP raster milling is developed, that quantifies the main aspects of the path behavior with characteristic values. This enables a systematic analysis of the interactions, that need to be examined, and the development of an interconnection between the sub-models, which were created in the first project phase. In this way a model of the overall axis system is created. To minimize dynamic path deviations extended model based filter and control methods are examined. These include the Input-Shaping, to reduce cross-talk between the axes, as well as a tracking control, to increase the dynamic. These methods, which are known from the HPC manufacturing, need to be adapted to the high requirements for the precision of the UP manufacturing. Because of this, the underlying models of these methods are implemented in such a way, that they can be adapted to different process states, by using methods like the continuous parameter identification.In the last year of the project phase the potentials and limits of the developed methods are researched, taking into account the vibration stimulation of the cutting process and the influences of the additional components. Further, the overall performance of all developed methods is evaluated in cutting tests.