Sheet-bulk forming of tubes for joining applications

This paper draws from the fundamentals of sheet-bulk forming of thin-walled tubes to the proposal of a new joining process for fixing tubes to sheets by means of plastic deformation at room temperature. The work on sheet-bulk forming of tubes is focused on local thickening (boss forming) by partial compression of the wall thickness along the longitudinal direction. The main goals are the understanding of the deformation mechanics of sheet-bulk forming of thin-walled tubes and the characterization of its formability limits in terms of the major process parameters. The work on joining by forming investigates how local thickening can be successfully utilized for fixing tubes to sheets by mechanical locking with a flaring die. The overall presentation is supported by finite element analysis and experimentation, and includes examples of joints made from dissimilar materials.