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

为了减轻重量和增加功能，现代轻质结构中的零件和部件由不同的材料组成。复合材料的性能差异很大，这对连接技术提出了很高的要求。传统的和广泛使用的连接方法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成形连接方法。它是传统热、机械或粘合剂连接工艺的替代品，可用于过盈配合和/或形状配合接头。由于其高度的工艺可靠性和易于监控的工艺，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。这意味着当前对旋转对称的接合伙伴的限制应当解除，使得具有多边形或椭圆形横截面的接合伙伴也可以成功地接合。实现这一目标需要开发非旋转对称截面的连接工具以及连接和工艺设计方法。第一个矩形截面型材的原型工具已经开发出来，并由成形技术和轻型结构研究所申请专利。这一概念应在本研究项目中通过实验和数值研究进一步发展。增加内连接件的最大允许尺寸偏差是刀具结构领域的主要目标之一。在随后的步骤中，将确定连接伙伴中的应力和应变分布，并将其与连接强度相关联。基于这些信息的指导方针和方法的接头和工艺设计将得出。最后，该项目提供了一个灵活的连接通过形成过程，适用于干涉和/或形状配合连接的型材与非对称横截面的不同金属材料制成的。

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.