Selective influencing of stiffness and damping at joints by modifying the contact surface micro-geometry on components made of heat-treated steel

切削机床分别用于零件的生产和精加工。它们的需求不断增加。这是由于高强度和难加工材料的使用增加，由于高速或金属去除率而减少制造时间，以及关于要保持的公差和粗糙度值的更严格的设计规范。在这种情况下，被动阻尼尤为重要。通过螺钉连接的机械元件接触面等关节对阻尼的贡献很大。但是，良好的关节阻尼通常会导致关节刚度降低。该领域先前的研究表明，通过应用合适的表面处理或微观结构，可以实现强关节阻尼和高刚度的组合。然而，目前缺乏设计这种表面的基本科学原理。首先，在微观尺度上对接触条件进行了有限元模拟。从而了解了影响关节阻尼和刚度的机理。在此基础上，根据制造技术定义和实现了表面几何形状。表面是这样设计的，它们可以在最终加工过程中直接生成。利用压力测量片分析了接头的载荷相关应力分布。基于对单个和组合试件的广泛频率响应分析，提取了固有频率和阻尼比。这些代表了宏观尺度上参数化有限元模型的目标函数，从而服务于压力相关关节阻尼和刚度的识别。因此，表面光洁度、表面压力与关节阻尼和刚度之间存在因果关系。这些关系使设计适合生产的表面，这需要特别强的振动阻尼，同时保持关节刚度。因此，机床的性能可以通过这样一种方式得到改善，即在考虑经济限制的同时，可以实现对部件公差和表面性能的更高要求。

Cutting machine tools are used for the production and finishing of components respectively. They are subject to increasing requirements. These result from a growth in the use of both high-strength and difficult-to-machine materials, the reduction of manufacturing time due to high speeds or metal removal rates, and stricter design specifications with regard to the tolerances and roughness values to be maintained. Passive damping is of particular importance in this context. Joints like the contact surfaces of machine elements connected by screws contribute significantly to damping. But, good joint damping typically leads to reduced joint stiffness. Previous studies in this field indicate that a combination of strong joint damping and high stiffness is possible by applying a suitable surface finish or micro structuring. However, fundamental scientific principles for the design of such surfaces are currently lacking. Firstly, finite element simulations on a microscopic scale are carried out to model the contact conditions. As a result, an understanding of the mechanisms influencing joint damping and stiffness is obtained. Based on this, surface geometries are defined and implemented in terms of manufacturing technology. The surfaces are designed in such a way that they can be generated directly during final machining. Pressure measurement foils are used to analyse the load-dependent stress distribution in the joint. Based on extensive frequency response analyses of both the individual and the assembled specimens, natural frequencies and damping ratios are extracted. These represent the objective functions in a parameterised FEA model on a macroscopic scale and thus serve the identification of pressure-dependent joint damping and stiffness. As a result, causal relationships exist between the surface finish, the surface pressure and the joint damping and stiffness. These relations enable the design of surfaces suitable for production, which entail particularly strong vibration damping while retaining the joint stiffness. Consequently, the behaviour of machine tools can be improved in such a way that increased demands on components in terms of tolerances and surface properties can be realised while taking into account economic constraints.