Surface structures on deep drawing tools by machine hammer peening to reduce friction and wear

深拉深是汽车工业生产三维零件的一项主要生产技术。最近的趋势强制使用高强度钢。因此，对拉深模具的摩擦性能和耐磨性提出了严格的要求。在全球范围内，工具和模具制造工业过程中的摩擦和磨损造成的成本高达数十亿欧元。在拉深工具上采用特殊设计的表面结构是减少成形过程中摩擦和磨损的一种有前途的方法。根据目前的技术状况，使用表面结构工具对摩擦学性能的描述还没有得到充分的探索。对于钣金工件的表面结构，已经显示了相互作用固体对摩擦和磨损特性的积极影响，但在深拉深过程中，它们与工具的表面结构在塑性扁化方面存在显著差异。因此，在深拉深工具上开发耐磨的表面结构是一项挑战，它对摩擦和磨损特性有积极的影响。未充分探索的机械锤击技术会产生表面结构。机锤强化与其他结构工艺的区别在于产生残余压应力和应变硬化。由于易于集成到现有的制造工艺和灵活可调的过程运动学，机床锤击强化提供了一个高的潜力，以满足对低摩擦和耐磨的工具结构的要求。这个项目的目的是发展一个分析-经验和数值过程模型来描述和解释机器锤强化产生的表面结构的基本因果关系，旨在减少深拉深过程中的摩擦和磨损。第一步探讨了机锤强化工艺参数与面层状态的基本关系。在此基础上，第二步描述和解释结构表面对摩擦和磨损的影响。重点研究了由机床锤击、润滑剂和钣金材料构成的刀具表面的摩擦学作用机理。获得的基本理解允许有目的的工艺设计，以减少在深拉深过程中的摩擦。根据确定的摩擦性能，探讨了表面结构对磨损特性的影响。

Deep drawing is a major production technology of the automotive industry for the production of three-dimensional components. Recent trends enforce the use of high strength steels. Therefore, the deep drawing tools have to fulfill stringent requirements on their friction characteristics and wear-resistance. Worldwide friction and wear in industrial processes for tool and die manufacturing cause costs up to billion euros. A promising approach to decrease friction and wear in forming processes is the use of special designed surface structures on deep drawing tools. The description of tribological performances using surface-structured tools is not sufficiently explored according to the current state of the art. For surface structures on sheet metal workpieces, positive impacts on the friction and wear characteristics of the interacting solids were already shown, but they differ significantly from surface structures on tools in their plastic flattening during deep drawing. Accordingly, the challenge is to develop wear-resistant surface structures on deep drawing tools which have a positive impact on friction and wear characteristics.The surface structures will be produced by the insufficient explored technology machine hammer peening. Machine hammer peening distinguishes itself from other structuring processes by the induction of residual compressive stresses and strain hardening. Due to an easy integration into existing manufacturing processes and the flexible adjustable process kinematics machine hammer peening offers a high potential to fulfill the requirements on the structuring of low-friction and wear-resistant tool structures.The aim of this project is the development of an analytic-empiric and numeric process models to describe and explain the fundamental cause-effect-relationships of surface structures produced by machine hammer peening intended to decrease friction and wear in deep drawing. The first step explores basic correlation between the machine hammer peening process parameters and the surface layer state. On this basis, in a second step the impact of structured surfaces on friction and wear is described und explained. The investigation is focused on the comprehension of tribological mechanism of action considering tool surfaces structured by machine hammer peening, lubricant and sheet metal material. The gained fundamental understanding allows a purposeful process design in order to decrease the friction in deep drawing processes. The exploration of the impact of the surface structure on the wear characteristics with respect to the determined friction properties follows in conclusion.