Fundamental investigations on the effect of structured functional surfaces of milling tools regarding process dynamics

机械加工过程的生产率往往受到诸如再生颤振等动态效应的限制。在文献中定义了影响过程动态的五个选项：系统刚度和系统阻尼的增强、过程参数选择、过程阻尼最大化和再生干扰。增加机床的刚度或阻尼在工程和设计过程中构成了挑战，与高成本相关，并且在可扩展性方面受到限制。优化的工艺设计和参数选择需要详细确定生产系统的动态特性和工艺动态学领域的广泛专业知识。最大化过程阻尼和干扰再生效应在很大程度上独立于生产系统和过程的一般条件，这就是为什么这些方法在提高生产率的普遍适用策略的意义上特别有趣。所提出的项目方法旨在通过在铣刀的次要功能表面上应用定义的结构来抑制或破坏再生颤振。根据工作假设，这些结构应该，例如，吸收横向力，引导切削运动或引起摩擦效应，从而抵消动态偏转。使用实验研究，可以证明一个定义的功能表面结构的过程稳定的潜力。高速钢铣刀副切削刃的后刀面制备有圆形结构，应用于铣削操作，并就实验确定的稳定性极限进行评估。与主轴转速无关的工艺稳定性和生产率可提高高达60%。该项目的目的是对结构设计和过程动态之间的因果关系进行基础研究。为此，将开发一种模拟实验台，它降低了从铣削到正交切削的切屑形成过程的复杂性。动态偏转由振荡工具系统的限定激励表示。在基础研究的范围内，将测量和分析各种结构特征对切屑形成过程的影响。此外，选定的结构变体将被转移到旋转对称的铣削工具，并随后应用和评估其在铣削操作中的工艺稳定性潜力。

The productivity of machining processes is often limited by the occurrence of dynamic effects such as regenerative chatter. Five options to influence the process dynamics are defined in literature: The enhancement of the system stiffness and system damping, the process parameter selection, the process damping maximization, and the regeneration disturbance. Increasing the stiffness or damping of machine tools constitutes a challenge in engineering and design processes, is associated with high costs and restricted in terms of scalability. An optimized process design and parameter selection require a detailed determination of the dynamic properties of the production system and extensive expert knowledge in the field of process dynamics. Maximizing process damping and disturbing the regenerative effect is largely independent of the general conditions of the production system and process, which is why these methods are particularly interesting in the sense of a universally applicable strategy for increasing productivity. The presented project approach intends to damp or disrupt regenerative chatter vibrations by applying a defined structure on the minor functional surfaces of a milling tool. According to the working hypothesis, these structures should, for example, absorb transverse forces, direct the cutting motion or cause friction effects and thus counteract dynamic deflections. Using experimental investigations, the potential of process-stabilization of a defined functional surface structuring could be demonstrated. The flank face of the minor cutting edge of an HSS milling tool was prepared with circular structures, applied in milling operations and evaluated regarding the experimentally determined stability limit. A spindle speed-independent increase of the process stability and productivity of up to 60% could be achieved. The aim of the project initiative is to conduct fundamental research on the causal relationships between structural designs and process dynamics. For this purpose, an analog experimental rig is going to be developed, which reduces the complexity of the chip formation process from milling to an orthogonal cut. Dynamic deflections are represented by a defined excitation of the oscillating tool system. Within the scope of fundamental investigations, the influence of various structural features on the chip formation process will be measured and analyzed. In addition, selected structural variants are going to be transferred to rotationally symmetrical milling tools and subsequently applied and evaluated with regard to their potential for process stabilization in milling operations.