Joining tubes to sheets by boss forming and upsetting

This paper draws from new developments in boss forming of tubes to the proposal of a new joining by forming process for fixing tubes to sheets at room temperature. The process takes place in two stages and involves the production of an annular flange by partial compression of the tube wall thickness along the longitudinal direction and the upsetting of the free tube end against a sheet with a bevelled hole in order to lock the two parts together. The presentation includes an analytical model for designing the joints and the validation of the overall joining concept by means of finite element modelling and experimentation. Destructive tests demonstrate the effectiveness of the new proposed joining process.