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Enhancement of the connection strength of flat-clinch joints by alternative process concepts

通过替代工艺概念增强平压铆接头的连接强度

基本信息

批准号：
334546496
负责人：
Professorin Dr.-Ing. Birgit Awiszus
金额：
--
依托单位：
Institut für Werkzeugmaschinen und Produktionsprozesse
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/334546496?language=en
关键词：
Enhancement connection strength flat clinch

项目摘要

The objective of the proposed project is the enhancement of the connection strength of flat-clinch joints by developing alternative process concepts and load-capable design concepts. By means of load-capable design concepts, it is possible to determine the application-related requirements concerning the connection strength (tensile strength, shear strength, torsional strength) of flat-clinch joints. Based on the knowledge gained, the optimal joining geometry and the required process parameters are derived. Furthermore, a novel simulation approach - the numerical computation using mesh-free methods - is used for enhancing the accuracy of the 3D simulation of flat-clinch joints as well as reducing the computing time.By using non-rotationally symmetric tool geometries, the torsional strength is increased compared to flat-clinching with a circular punch. Because of the irregular tool cross section, the interlocking between the metal sheets is expected to be irregular as well. During the project, different tool geometries will be developed for producing torsion-proof flat-clinch joints with high resistance to tensile and shear stress.By inserting local joining elements, the tensile strength and shear strength of conventional flat-clinch joints with circular punch geometries will be increased. Cylindrical blanks are inserted into the flat-clinch joint and subsequently formed in mainly radial direction. This second process step leads to an increased interlocking between the metal sheets and thus to an increase of the tensile strength. Furthermore, the bottom thickness, at which the joining element is inserted, will be investigated. By choosing a higher bottom thickness during the first process step (conventional flat-clinching), the punch-sided metal sheet undergoes less thinning, resulting in a higher neck thickness. During the second process step, the forming of the joining element leads to an interlocking that is comparable to the interlocking of conventional flat-clinching. Because of the higher neck thickness, the shear strength of the flat-clinch joint is higher as well. The aim of the investigations is to develop an understanding of the related joining mechanisms to detect the proper bottom thickness for inserting the joining element as well as the optimal geometry and material of the joining element depending on the thickness and material of the metal sheets.

该项目的目标是通过开发替代工艺概念和负载能力设计概念来提高平铆接头的连接强度。通过承载设计概念，可以确定与应用相关的平压接接头连接强度（抗拉强度、抗剪强度、抗扭强度）要求。根据所获得的知识，最佳的连接几何形状和所需的工艺参数。此外，一种新的模拟方法-使用无网格方法的数值计算-被用来提高平铆接接头的三维模拟的准确性，以及减少计算时间。通过使用非旋转对称的工具几何形状，扭转强度增加相比，平铆接与圆形冲头。由于不规则的工具横截面，金属板之间的互锁预计也是不规则的。在该项目中，将开发不同的模具几何形状，用于生产具有高抗拉和抗剪应力能力的防扭转平压接接头。通过插入局部连接元件，将提高采用圆形冲头几何形状的传统平压接接头的抗拉强度和剪切强度。圆柱形坯料被插入到平压接接头中，并且随后主要沿径向方向形成。该第二工艺步骤导致金属板之间的互锁增加，并因此导致抗拉强度增加。此外，将研究插入连接元件的底部厚度。通过在第一工艺步骤（常规平铆）期间选择较高的底部厚度，冲压侧金属板经历较少的减薄，导致较高的颈部厚度。在第二工艺步骤期间，连接元件的形成导致与传统的平铆的互锁相当的互锁。由于颈部厚度较大，平铆接头的剪切强度也较高。研究的目的是了解相关的连接机制，以检测插入连接元件的适当底部厚度以及连接元件的最佳几何形状和材料，这取决于金属板的厚度和材料。