Process-independent force and surface model for oblique cutting of fiber reinforced polymers

纤维增强聚合物常用于轻量化设计。由于正交各向异性材料的特性，切屑去除过程中的切削机制与各向同性材料的切削机制有很大不同。到目前为止，对正交切削的基本机理进行了初步的研究。然而，斜切削通常存在于工业实践中，其中由于刀具切削刃的空间啮合条件而发生三维切削过程。空间啮合条件由切削刃的三维空间方向和相对于纤维的切削方向的组合产生。初步研究表明，三维空间刀具-纤维取向对切削力和最终切削面有显著影响。表面完整性影响轻量化结构在静、动载荷作用下的力学性能。特别是，发生纤维拔出对表面完整性至关重要。该项目的目标是加工纤维增强聚合物的切削力和表面模型，特别考虑斜切削。切削力的预测基于半经验模型，该模型具有与工艺无关的有效性。模型将被转移到铣削。此外，预计在第二个项目阶段将转向钻井和反沉。创新的实验装置首次能够在高切割速度以及刀具的任意方向和相对于纤维的切割方向下有效和全面地识别切割力系数。该表面模型是根据空间荷载情况与实测表面状况的相关性建立的。它可以预测与表面质量有关的关键切割条件，特别是纤维拔出。对加工力和切削表面的旋转角度相关模拟可以得出三维空间啮合条件下的特定加工机制的结论，这是迄今为止由于正交切削的关注而无法实现的。与钻孔或铣削过程中单纯的机械力校正模型相比，半经验模型显示了沿切削刃的载荷分布。这使得仅影响刀具一小部分区域的现象得以分析，并在表面质量方面显示出优化潜力。

Fiber reinforced polymers are often used in lightweight design. Due to the orthotropic material properties, the cutting mechanisms during chip removal differ significantly from those of isotropic materials. So far, the fundamental mechanisms have been investigated primarily for orthogonal cutting. However, oblique cutting is generally present in industrial practice, in which a three-dimensional cutting process occurs due to the spatial engagement conditions of the tool’s cutting edges. The spatial engagement conditions result from a combination of the 3D spatial orientation of the cutting edge and the cutting direction with respect to the fiber.Preliminary studies reveal a significant influence of the 3D spatial cutter-fiber-orientation on the cutting forces and the resulting cutting surface. The surface integrity can affect the mechanical behavior of lightweight structures under static and dynamic loads. In particular, occurring fiber pull-out is critical for the surface integrity. The objective of the project is a cutting force and surface model for the machining of fiber reinforced polymers with particular consideration of oblique cutting. The prediction of cutting forces is based on a semi-empirical model, which has a process-independent validity. The model will be transferred to milling. Furthermore a transfer to drilling out and countersinking is envisaged in a second project phase. Innovative experimental setups enable efficient and comprehensive identification of cutting force coefficients for the first time, also under high cutting speed as well as arbitrary orientation of the cutter and cutting direction relative to the fiber. The surface model is developed from the correlation between the spatial load situation and the measured surface condition. It allows the prediction of critical cutting conditions with respect to surface quality, in particular fiber pull-out. The rotation-angle-dependent simulation of the process forces and the cutting surfaces allows conclusions to be drawn about the process-specific mechanisms in terms of 3D spatial engagement conditions, which has not been possible up to now because of the focus on orthogonal cutting. Compared to the mere mechanistic force modelling by calibration in a drilling or milling process, the semi-empirical model shows the load distribution along the cutting edge. This enables the analysis of phenomena which are only affecting a small region of the cutter and shows optimization potential in terms of surface quality.