Joining by die-less hydroforming of profiles with non-rotationally-symmetric cross section

为了减轻重量和增加功能，现代轻量化结构中的零部件是由不同的材料组成的。复合材料性能的高度多样性对连接技术提出了很高的要求。传统的和广泛使用的连接工艺达到了它们的技术极限或在经济方面不再具有竞争力。无模液压成形连接是一种通过成形连接的工艺。它是传统的热连接、机械连接或粘接连接工艺的替代，可用于过盈配合和/或成形配合连接。由于其高工艺可靠性和易于工艺监控，它非常适合自动化制造工艺。为了利用这些潜力，拟议的研究项目旨在扩大目前的工艺限制。这意味着应该取消目前对旋转对称连接伙伴的限制，以便也可以成功地连接具有多边形或椭圆形截面的连接伙伴。为了实现这一目标，需要开发用于非旋转对称截面的连接工具以及连接和工艺设计的方法。第一个用于矩形截面型材的原型工具已经开发出来，并申请了成形技术和轻量化结构研究所的专利。这一概念应通过实验和数值研究在本研究项目中得到进一步发展。增加内连接件的最大允许尺寸偏差是工具制造领域的主要目标之一。在接下来的步骤中，将确定连接伙伴中的应力和应变分布，并将其与连接强度进行关联。基于这些信息，将得出接头和工艺设计的指导方针和方法。最后，该项目通过成形工艺提供了一种灵活的接头，适用于由不同金属材料制成的非对称截面型材的干涉和/或成形配合接头。

For reason of weight reduction and increased functionality parts and components in modern lightweight constructions are composed of different materials. The high diversity in the properties of the combined materials makes high demands on the joining technology. Conventional and widely used joining processes reach their technological limits or are no longer competitive in terms of economic aspects.Joining by die-less hydroforming is a joining by forming process. It is an alternative to conventional thermal, mechanical or adhesive joining processes and can be used for interference fit and/or form fit joints. Because of its high process reliability and easy process monitoring it is well suited for automated manufacturing processes. To make use of these potentials the proposed research projects aims on an expansion of the current process limits. This means that the current limitation on rotationally symmetric joining partners should lifted so that also joining partners with polygonal or elliptical cross section can be joined successfully. Achievement of this objective requires the- development of joining tools for non-rotationally symmetric cross sections and- approaches for joint and process design.A first prototype tool for profiles with rectangular cross section has already been developed and applied for patent by the Institute of Forming Technology and Lightweight Construction. This concept should be developed further within this research project by experimental and numerical investigations. Increase of the maximum allowable dimensional deviations of the inner joining partner is one of the major objectives in the field of tool construction. In the subsequent step the stress and strain distribution in the joining partners will be determined and correlated with the connection strength. Based on these information guidelines and approaches for joint and process design will be derived.Finally the project provides a flexible joining by forming process suitable for interference and/or form fit joints of profiles with non-symmetrical cross section made of different metallic materials.