Laser implantation of press hardening tools to influence the tribological and thermal properties for the process application

汽车工业的主要发展目标是提高乘客的安全性以及降低燃料消耗和实现排放法规。因此，热冲压已被确定为制造高强度和轻质白色车身部件的合适且资源高效的工艺。然而，由于高的热机械工具应力和缺乏润滑剂，生产受到摩擦和磨损的限制。该研究项目的总体目标是通过使用激光注入工艺来修改工具表面，以影响接触区中的热、机械和摩擦学相互作用。在第一个项目阶段，通过数值模型确定了摩擦学高应力工具区域以及对植入物几何形状的要求。确定了合适的硬质陶瓷颗粒，并分析了不同激光参数对硬质陶瓷颗粒的影响。摩擦学实验表明，激光注入刀具具有高的耐磨性和降低摩擦力，由于接触面积的限制和减少的化学亲和力之间的工具和工件。通过修改与工业相关的模具几何形状，最终证明可以提高零件质量并改善成形性能。然而，根据数值计算结果，最大的工具负载位于几何形状复杂的区域，不能被激光注入，由于缺乏注入策略和未知的因果关系之间的工具和工件。因此，预计结构化这些高应力工具区域将显著改善摩擦学行为。在第二个项目阶段，必须开始对不同的刀具应力进行进一步的研究，以确定表面特性、摩擦和磨损行为之间的相互作用。在这种情况下，将针对特定的负载情况创建由硬相组合物和定制的结构化图案制成的合适的植入物。之后，它们将在工业相关实验中进行测试，以验证其有效性。这种方法提供了一个更深入的了解之间的相互作用的硬陶瓷颗粒和植入物的安排在高应力工具领域。

Major development goals of the automotive industry are to increase the passenger safety as well as to reduce the fuel consumption and to achieve emission regulations. Hence, hot stamping has been established as a suitable and resource efficient process to manufacture high-strength and lightweight body-in-white components. However, the production is limited by friction and wear due to high thermo-mechanical tool stresses and the lack of lubricants. The overall aim of this research project is to modify the tool surface by using a laser implantation process in order to influence the thermal, mechanical and tribological interactions in the contact zones. Within the first project phase, tribological highly stressed tool areas as well as requirements for the implant geometry were identified by means of numerical models. Furthermore, suitable hard ceramic particles were determined and their interactions with different laser parameters were analyzed. Tribological experiments have shown that laser-implanted tools exhibit a high wear resistance and decreasing friction forces due to the limitation of the contact area and the reduced chemical affinity between tool and workpiece. By modifying an industry-related tool geometry, it was finally proven that an increased part quality and an improved forming behavior was achieved. However, based on the numerical results, maximum tool loads were located in geometrical complex areas which could not be laser-implanted due to the lack of implantation strategies and the unknown cause-effect relations between the tool and the workpiece. Thus, it is expected that structuring these highly stressed tool areas will significantly improve the tribological behavior. In a second project phase, further investigations with regard to varying tool stresses must be initiated in order to identify the interactions between surface properties, friction and wear behavior. In this context, suitable implants made out of hard phase compositions and tailored structuring patterns will be created for specific load cases. Afterwards, they will be tested in industrially relevant experiments to verify their effectiveness. This approach provides a deeper understanding regarding the interactions between hard ceramic particles and the arrangement of the implants in highly stressed tool areas.