Micro-structuring and macro-structuring of deep drawing tools for dry forming condition

成形过程中的大摩擦力减小了工艺极限。因此，通常使用润滑剂来减少摩擦和扩大工艺窗口。然而，润滑油的技术优势伴随着负面的经济和生态影响。因此，在本项目中，研究和分析了通过保护涂层和工具微观和宏观结构的综合概念来消除深拉深过程中的润滑剂。在第一阶段，对综合方法的不同技术进行了基本分析，并对刀具结构拉深工艺进行了实验验证。对轴对称零件进行了总体可行性论证。在第二个资助期，过程原则得到进一步完善。为了提高工艺设计的时效化，建立了描述输入参数对起皱和底部裂纹风险影响的解析模型。此外，一项关于高强度钢的可行性研究表明，宏观结构的深拉深工艺比标准工艺具有额外的优势。通过研究涂层技术和刀具的微观结构来减小摩擦力，并研究了涂层和结构表面的磨损行为以及与毛坯和刀具表面的相互作用。所有的技术转移到设计一个模块化的工具，非轴对称零件。基于这些结果，第三个研究阶段的目标是实现工业相关的复杂零件和高强度材料的无润滑剂拉深工艺。主要的方法仍然是在宏观结构、涂层和微观结构领域的不同工艺的综合应用。将宏观结构增强为三维几何形状是一个关键因素，因为它可以直接控制材料在切向和径向上的流动，因此可以系统地调整应力以及弯曲和不弯曲以具体设置零件特性。采用调整后的半解析模型进行宏观结构设计和工艺参数选择。成形过程中对刀具的摩擦和磨损的相应高要求将通过涂层和微结构相结合的方法来解决。目标是通过调整涂层和结构工艺来改善先前的结果。具体来说，一种带有氟改性ta-C层的新涂层将被实现，铬键合层将被硝化工艺取代。此外，DLIP工艺将通过缩短脉冲时间和均匀化激光束来调整，以提高微结构的质量，同时最大限度地减少对基板的负面影响。所有技术都将使用第二阶段的模块化深拉深工具进行集成和验证。

Large friction forces in forming processes reduce the process limits. Generally, lubricants are therefore used to reduce friction and enlarge the process window. However, the technological advantages of lubricants are accompanied by negative economic and ecological effects. Therefore, the elimination of lubricants from deep drawing processes by means of an integrated concept of a protective coating and micro- and macro structuring of the tool is studied and analysed during this project. Within the first phase, the different technologies of the integrative approach were fundamentally analysed and the deep-drawing process with tool structuring was experimentally verified. The general feasibility was demonstrated for axially symmetric parts. In the second funding period, the process principle has been further improved. For a time efficient process design an analytical model has been developed describing the influence of input parameters on the risk of wrinkling and bottom cracks. Furthermore, a feasibility study regarding high-strength steels indicated additional advantages of a macro-structured deep drawing process over standard processes. The reduction of friction forces was pursued by investigating coating technology and micro-structuring of tools and the wear behaviour of coated and structured surfaces and the interaction with blank and tool surface were investigated. All technologies were transferred to the design of a modular tool for non axially symmetric parts. Based on these results, the third research phase has the goal to implement an industrially relevant lubricant free deep drawing process for complex parts and high strength materials. The main approach remains an integrative application of different processes in the areas of macro-structuring, coating and micro-structuring. The enhancement of the macro-structuring into three-dimensional geometries is a key factor, because it allows the direct control of the material flow in tangential and radial direction, and therefore the systematic adjustment of stresses as well as bending and unbending to specifically set part characteristics. An adjusted semi-analytical model is used for designing the macro-structures and choosing process parameters. The corresponding high requirements of the forming process regarding friction and wear of the tools will be addressed with a combined approach of coating and micro-structuring. The goal is to improve on previous results by adjusting the coating and structuring processes. Specifically, a new coating with a fluor modified ta-C layer will be implemented and the chromium bonding layer will be substituted by a nitration process. Additionally, the DLIP process will adjusted by shortening pulse times and homogenising the laser beam in order to improve the quality of the micro-structure while minimising negative effects on the substrate. All technologies will be integrated and verified using the modular deep drawing tool from the second funding phase.