Development of a methodology for the extension and deflection-based calibration of an axis-position sensitive process force model

工艺模拟可以改进铣削工艺的设计，以达到所需的工件质量和高生产率。例如，基于几何物理的工艺模拟被用来预测所产生的表面质量并避免颤动振动。这些模拟使用了生产系统的顺应性和过程作用力的模型。切削力模型的经验校准是基于所分析的材料和刀具组合的力测量，使用诸如进化算法等各种优化技术来执行的。力模型的参数化是模糊的，因为不同的参数值组合可以产生相对较好的过程力建模。然而，这些不同的校准可能导致在模拟振动时预测不同的挠度。此外，用于测力的测力计由于其传递行为和遵从性，限制了可用于研究的过程参数值的范围。在本项目中，将开发一种新的过程力模型的参数化方法。通过考虑在加工过程中测量的刀具挠度，将能够明确地确定加工力系数。基于刀具挠度和激励力之间的物理相互作用，考虑到系统的已知柔度，可以从挠度到制程力得出结论。在对材料-工具组合进行了基于力测量的初始参数化之后，然后应基于挠度测量进行参数优化。与力测量不同的是，这些测量是使用涡流传感器进行的，并且对过程行为没有影响。为了确保使用球形形状元件的刀具模拟铣削过程有足够的预测精度，需要开发一个扩展力模型。根据Kienzle的切削力模型，将同时考虑刀具方向和沿切削刃变化的啮合条件。此外，还计划研究模型校准对其他材料(以钢和铝材料为例)和工具的可移植性。根据测量的挠度校准扩展力模型的新方法有望实现对加工力和刀具挠度的明确预测，并扩大模型的有效范围。

Process simulations enable an improved design of milling processes in order to achieve the required workpiece quality and high productivity. For example, geometric physically-based process simulations are used to predict the resulting surface quality and avoid chatter vibrations. These simulations use models of the compliance of the production system and the process forces. The empirical calibration of the cutting force models is performed using various optimization techniques, such as evolutionary algorithms, on the basis of force measurements for the analyzed combination of material and tool. The parameterization of a force model is ambiguous, as different parameter value combinations can lead to a comparably good modeling of the process forces. However, these different calibrations can result in the prediction of different deflections when simulating vibrations. Furthermore, the dynamometers used for force measurement limit the range of process parameter values which can be used in the investigations due to their transfer behavior and compliance.In this project, a new methodology for the parameterization of process force models will be developed. By taking into account tool deflections measured in the process, the unambiguous determination of process force coefficients will be enabled. Based on the physical interactions between the tool deflections and the exciting process forces, it is possible to draw conclusions from the deflections to the process forces, considering the known compliance of the system. After an initial parameterization based on force measurements for a material-tool combination, the parameter optimization should then be carried out based on deflection measurements. In contrast to force measurements, these are performed contact-free using, e.g., eddy current sensors and have no influence on the process behavior.To ensure sufficient prediction accuracy for the simulation of milling processes with tools with spherical form elements, an extended force model is to be developed. Based on the cutting force model according to Kienzle, both, the tool orientation and the varying engagement conditions along the cutting edge will be taken into account. Furthermore, investigations on the transferability of the model calibration to other materials (using steel and aluminum materials as examples) and tools are planned. The new methodology for calibrating the extended force model based on measured deflections is expected to achieve an unambiguous prediction of process forces and tool deflections and an extended range of validity of the models.