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Joining by dieless hydroforming with outer pressurization

通过外部加压无模液压成形连接

基本信息

批准号：
350070123
负责人：
Professor Dr.-Ing. A. Erman Tekkaya
金额：
--
依托单位：
Institut für Umformtechnik und Leichtbau (IUL)
依托单位国家：
德国
项目类别：
Research Grants (Transfer Project)
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/350070123?language=en
关键词：
Joining dieless hydroforming outer pressurization

项目摘要

Lightweight construction requires weight optimization of structures and components. This is often realized by the integration of functions or the combination of different material properties in one single component. Due to the high diversity of material properties there are high demands on the joining technology which lead to technological or economic limits of conventional joining processes.A suitable alternative to conventional methods is the process of joining by die-less hydroforming. This process allows the production of interference fit and/or form fit joints, which makes it suitable for joining mixed compounds. By recording the pressure data of the working media it is easily possible to monitor the process which qualifies it for process automation. At present, the application range is limited by the inner accessibility. The project aims at extending the process limits by reversing the forming direction to join parts with limited inner accessibility like strongly curved or especially long profiles and also to seal rotationally symmetric containers. Instead of a radial expansion by internal high pressure there is a radial compression by external pressure. Potentially, this leads to an increase of the application range and promotes the industrial acceptance of the technology. To achieve the project objective, it is necessary - to develop tool concepts for the reliable pressurization and- to generate approaches for joint and process design.A first prototype tool was developed and used for feasibility investigations at the Institute of Forming Technology and Lightweight Construction. A static seal system was used, with the workpiece tolerance negatively affecting the sealing effect or leading to high sealing wear because of increased preload forces. Consequently, the tool technology has to be improved by using numerical and experimental investigations. The stress and strain distributions in the joining partners differ at different joining directions. Since they influence the bond strength, their determination is essential for the derivation of approaches and guidelines for process and joint design. A final comparison of the processes (with external and internal high-pressure initiation) shows the respective economy and allows to define an overall process window. The knowledge will be transferred to industrial practice by process application to demonstration parts of the cooperation partners. Finally, the project provides an industrially proven, flexible joining by forming process suitable for interference and/or form fit joints with different material combinations and external accessibility.

轻量化结构需要结构和部件的重量优化。这通常是通过在一个单一组件中集成功能或组合不同的材料特性来实现的。由于材料性能的高度多样性，对连接技术的要求很高，传统的连接工艺在技术和经济上都受到限制，无模液压成形连接工艺是一种合适的替代方法。该工艺允许生产过盈配合和/或形状配合接头，这使得其适合于连接混合化合物。通过记录工作介质的压力数据，可以轻松监控过程，从而使其符合过程自动化要求。目前，由于内部可达性的限制，应用范围受到限制。该项目旨在通过反转成型方向来扩展工艺极限，以连接内部可达性有限的部件，如强烈弯曲或特别长的型材，并密封旋转对称的容器。代替由内部高压引起的径向膨胀，存在由外部压力引起的径向压缩。潜在地，这导致应用范围的增加并促进该技术的工业接受。为了实现项目目标，有必要-开发可靠加压的工具概念，并-生成接头和工艺设计方法。第一个原型工具已开发出来，并在成型技术和轻型结构研究所用于可行性研究。使用了静态密封系统，工件公差会对密封效果产生负面影响，或者由于预加载力增加而导致密封磨损。因此，工具技术必须通过使用数值和实验研究来改进。在不同的连接方向上，连接件中的应力和应变分布不同。由于它们影响粘结强度，因此它们的确定对于工艺和接头设计的方法和指南的推导至关重要。最后比较的过程（与外部和内部的高压启动）显示各自的经济性，并允许定义一个整体的过程窗口。这些知识将通过应用于合作伙伴的示范部分的过程转移到工业实践中。最后，该项目提供了一种经过工业验证的灵活连接，适用于不同材料组合和外部可达性的过盈和/或形状配合接头。