Numerical multiscale modelling and optimization of cooling concepts in gear skiving

该项目旨在模拟润滑和冷却与由此产生的切屑形成的动力剥落，这是一个运动复杂且难以接近的齿轮加工过程。切削条件沿着切削刃和在加工过程中变化。由此产生的多部分切屑通过粘附在工件或刀具表面或夹在工件和间隙面之间而反复破坏加工过程。这就造成了挤压切屑等影响，从而导致表面缺陷和刀具磨损。只有在冷却润滑剂影响下的切屑形成模型才能理解这些缺陷的发生。影响切屑形成的主要因素是工艺参数和切屑与前刀面之间冷却润滑剂的作用。在实践中，润滑油应用的优化是基于经验的。基于模型的工艺优化需要考虑润滑油的应用和分布，以及对切屑与前刀面摩擦的影响，当然还有对切屑形成和切屑流动的影响。然而，整个过程过于复杂，无法在单个模型中复制。因此，需要建立一个流动模型与切屑形成模型和摩擦模型耦合的模拟。第二阶段资助的目的是将已开发的正交键合切割耦合模拟方法应用于压缩空气和油驱冷却的复杂动力剥皮过程。在摩擦学、切屑形成和流体流动等子领域的多尺度水平上考虑了导致切屑挤压的复杂机制。采用有限元方法模拟了切屑的形成过程。利用VOF和SPH方法对冷却润滑概念进行了建模，并利用分子动力学和量子化学模拟研究了刀具与工件之间的摩擦，考虑了冷却润滑剂对切屑形成和刀具粘附的影响。第一步是将单个子区域的模拟模型转移到剥皮过程，然后将它们耦合起来，以获得整个过程和所考虑的尺度区域的复杂相互作用的整体视图。这种不同冷却润滑策略影响的模拟映射为描述导致切屑挤压的主要影响机制奠定了基础。在该项目的第三阶段，基于对切屑挤压发展的理解，将参考所研究的鳞片的主要机制开发合适的冷却润滑策略，并可在未来用于设置稳定，有利的切屑形成，从而获得更好的表面和更长的刀具寿命。

The project aims in modelling the lubrication and cooling with resulting chip formation in power skiving, a kinematically complex and inaccessible machining process for gears. The cutting conditions vary along the cutting edge and during the process. The resulting multi-part chips repeatedly disrupt the process by adhesion to workpiece or tool surfaces or they get caught between workpiece and clearance face. This results in effects like squeezed chips, which lead to surface defects and tool wear. Only a model of the chip formation under the influence of the cooling lubricant enables understanding the occurrence of these defects. Dominant factors for chip formation are process parameters and the cooling lubricants effect between chip and rake face. In practice, the optimisation of the lubricants application is experience-based. A model-based process optimization requires considering the lubricants application and distribution, as well as the influences on the friction between chip and rake face and of course the effects on chip formation and chip flow. However, the entire process is too complex to be reproduced in a single model. Therefore, a simulation is to be created in which a flow model is coupled with a chip formation model and a friction model. The aim of the second funding phase is to transfer the developed coupled simulation methods of the orthogonal bonded cut to the complex power skiving process using compressed air and oil flood cooling. The complex mechanisms that lead to squeezed chips are considered on a multiscale level in the sub-areas of tribology, chip formation and fluid flow. Chip formation is modelled by means of an FEM simulation. The cooling lubrication concept is modelled using the VOF and SPH methods and the friction between tool and workpiece is investigated with molecular dynamic and quantum chemical simulations taking into account the cooling lubricant, which affects chip formation and adhesion to the tool. The first step is the transfer of the simulation models of the individual sub-areas to the skiving process and subsequently their coupling for a holistic view of the process and the complex interactions of the considered scale areas. This simulative mapping of the influence of the effect of the differently considered cooling lubrication strategies lays the foundation for describing the main effect mechanisms that lead to chip squeezes. In the third phase of the project, based on the generated understanding of the development of chip squeezes, suitable cooling lubrication strategies are to be developed with reference to the main mechanisms of the investigated scales and can be used in the future for the setting of a stable, advantageous chip formation and thus to better surfaces and longer tool life.