Lubricant free forming with tailored tribological conditions

在无润滑剂成形过程中，工件与刀具表面发生了强烈的相互作用。该研究项目的目的是通过开发和应用创新的摩擦学系统来实现干法成形工艺。干法成形的挑战，如摩擦增加和磨损增加，可以通过量身定制的工具方法进行基于工具的表面修改来解决。在本项目的第一阶段，研究了板材的无润滑拉深成形。为了检验推导出的关联式对其他材料类别的可转移性，还对一种铝合金进行了测试。在实验室条件下的基础实验中，通过对发生的摩擦学效应的分析和描述，对无润滑剂成形有了基本的了解。同时，测试结果可作为基于模拟的演示杯分段式工具设计的输入值。在有限元模拟中，确定了相关的摩擦学工具区域。随后，以逆方法导出每个工具段所需的曲面特性。这些要求代表了定制表面改性的发展目标。为了保证合理的耐磨性，对DLC涂层体系在无润滑剂拉深成形中的适用性进行了评估。在某些工具领域，无润滑剂成形要求涂层具有极高的耐磨性。在这方面，我们研究了DLC涂层的激光诱导热处理以提高其局部耐磨性。此外，为了控制材料流动的目的，基于工具的表面结构将通过激光烧蚀来开发和应用。在开发表面涂层和组织的同时，通过实验室条件下的模型试验，研究了不同变质类型的摩擦磨损行为。特别是量化了刀具材料、表面结构和涂层等因素对刀具性能的影响。为了确定干成形工艺的极限，在实验室试验中研究了刀具行为和发生的工艺载荷之间的相互作用。所导出的工艺载荷、表面修改和所产生的刀具行为之间的相关性被用于在无润滑剂模型工艺中对摩擦学条件进行局部调整。为了验证这些关联式，对所研究的钢和铝牌号在拉深过程中分段刀具的摩擦磨损行为进行了测定。该项目第一阶段的结果为定制摩擦学系统在无润滑剂成形工艺中的应用奠定了基础。

Within lubricant free forming an intensive interaction of workpiece and tool surface occurs. The aim of this research project is the realization of dry forming processes by developing and applying innovative tribological systems. The challenges of dry forming such as increased friction accompanied by increased wear are met by tool based surface modifications in a tailored tool approach. In the first period of the project forming of steel sheets is investigated in a lubricant-free deep drawing process. In order to test the transferability of derived correlations to other workpiece material classes also an aluminum alloy is tested. In basic experiments under laboratory conditions the fundamental understanding of lubricant free forming is generated by the analysis and description of the occurring tribological effects. At the same time the test results serve as input values for the simulation based design of the segmented tool for manufacturing the demonstrator cup. In the FE simulation tribological relevant tool areas are identified. Subsequently, required surface properties for each tool segment are derived in an inverse approach. The requirements represent the targets for the development of tailored surface modifications. In order to guarantee reasonable wear resistance the suitability of DLC coating systems for lubricant free deep drawing is assessed. In some tool areas lubricant free forming requires an extraordinary high wear resistance of the coatings. In this regard the laser induced heat treatment of DLC coatings is investigated for the local enhancement of wear resistance. Furthermore, for the purpose of controlling the material flow tool based surface structures will be developed and applied by laser ablation. While developing the surface coatings and structures the frictional and wear behavior of the different modification types are investigated by carrying out model tests under laboratory conditions. In particular, the influences of the factors tool material, surface structure and coating on the tool behavior are quantified. For determination of the limits of dry forming process the interactions of tool behavior and occurring process loads are investigated in the laboratory tests. The derived correlations between the process loads, the surface modifications and the resulting tool behavior are used for the local adjustment of the tribological conditions within the lubricant free model process. In order to validate these correlations the friction and wear behavior of the segmented tool is determined in the deep drawing process for the investigated steel and aluminum grade. The results of the first period of the project represent the basis for qualification of tailored tribological systems for the application in lubricant free forming processes.