Characterisation and modelling of the wear behaviour of coated cemented carbide tools used for turning a hard to machine steel

为了实现可持续和经济的未来切割制造工艺，需要大幅减少刀具方面的关键或稀有资源，如钨和钴，以及生产所需的能源。为了实现硬质合金刀具的这一目标，在不影响其使用性能的情况下，在多层设计中采用了复杂的高性能涂层，以延缓磨损过程，从而提高刀具寿命。此外，还使用了冷却润滑剂(冷却剂)系统，这不仅可以减少摩擦，还可以降低硬质合金的温度，从而改善其磨损性能。为了有效地设计专用工具概念，例如关于其工具形状，数值切屑形成模拟已经发展成为一种强大的工具。为了能够在将来借助模拟来设计硬质合金刀具的涂层概念，有必要建立真实的磨损过程模型。对于涂层特定磨损率模型的参数设置和验证，热机械载荷谱的知识至关重要。然而，由于可获得性有限，在加工过程中原位记录TCT上的温度梯度是一个巨大的挑战，这导致了对新的温度测量方法的需要。为了能够更准确地确定相关温度，上一个项目成功地开发了一种创新的试验台，在没有冷却剂的情况下，在包括准直器的比率高温计的帮助下，在正交车削过程中可以实现50微米的空间分辨率。该试验台将在拟议的续建项目范围内扩大，以便还能够表征冷却润滑剂对多层涂层硬质合金刀具的温度场以及由此产生的刀具磨损的影响。为此，建议在试验台中安装密封空气系统，去除工具和测量设备之间的冷却润滑剂，以便能够在接触区进行温度测量。通过记录与刀具刃口形状有关的异地测量数据，可以高度准确地描述HM刀具的初始状态，并监控整个刀具寿命内的磨损过程。获得的测量数据用于校准磨损率模型，从而可以根据冷却液策略和涂层特性进行单独的修改。在这些磨损率模型的基础上进行的切屑形成模拟将借助车削试验的实验数据进行验证，以预测刀具磨损。

The sustainable and economic future orientation of cutting manufacturing processes requires a significant reduction of critical or rare resources such as tungsten and cobalt on the tool side, as well as the energy required for production. In order to achieve this goal for carbide tools without impairing the operating properties, complex high-performance coatings in multilayer design are used so that the wear progress is delayed and thus the tool life is increased. In addition, cooling lubricant (coolant) systems are used, which not only reduce friction but also the temperatures at the carbide tols and thus also improve its wear behaviour. For an efficient design of application-specific tool concepts, e.g. with regard to their tool shape, numerical chip formation simulations have developed into a powerful instrument. In order to also be able to design the coating concepts of carbide tools with the aid of simulation in the future, realistic models of the wear progress are necessary. For the parameterisation and validation of coating-specific wear rate models, knowledge of the thermomechanical load spectrum is of central importance. Due to the limited accessibility, however, the in-situ recording of temperature gradients on the TCT during machining, especially with the use of cooling lubricants, represents a great challenge, which leads to the need for new temperature measurement methods. In order to enable a more precise determination of the relevant temperatures, the previous project succeeded in developing an innovative test rig on which a spatial resolution of 50 µm can be realised during orthogonal turning without coolant with the aid of a ratio pyrometer including collimator. This test rig is to be expanded within the scope of the proposed continuation project in order to also be able to characterise the influence of a cooling lubricant on the temperature field on multilayer-coated carbide tools as well as the resulting tool wear. To this end, it is advisable to implement a sealing air system in the test rig that removes the cooling lubricant between the tool and the measuring device in order to enable temperature measurement in the contact zone. By recording ex-situ measurement data relating to the shape of the cutting edge, a highly accurate description of the initial condition of the HM tool and a monitoring of the wear progress over the entire tool life is achieved. The measurement data obtained is used to calibrate the wear rate models, which enables individual modification depending on the coolant strategy and the coating properties. The chip formation simulations carried out on the basis of these wear rate models are to be validated with the aid of experimental data from the turning tests in order to predict the tool wear.