Joining by Forming of Tubes to Sheets with Counterbored Holes

Abstract

This paper presents a new joining by forming process for connecting tubes to sheets. The process consists of forming an annular flange with rectangular cross section by partial sheet-bulk of the tube wall thickness and performing the mechanical interlock by upsetting the free tube end against a flat-bottomed (counterbored) sheet hole. The presentation identifies the variables and the workability limits of the process and includes an analytical model to assist readers in the design of the new joints. The new proposed joining by forming process and the corresponding analytical model are validated by experimentation and numerical simulation using finite element analysis. The process allows connecting tubes to sheets made from dissimilar materials at room temperature, avoids the utilization of addition materials or adhesives and produces joints that are easy to disassembly at the end of live, allowing recyclability of the tubes and sheets.