Joining by forming - Newer developments

Abstract

Newer joining techniques by forming are introduced in this contribution. They increasingly substitute the conventional welding techniques which are often not suitable caused by heating of material. High strength material sensitively reacts to the temperature with a loss of fatigue strength. Moreover the sheet metals are often coated with organic protective layers, which e.g. are not electrical conductive. In this case joining by forming avoids these disadvantages and in dependence of the requirements the various techniques can be used like clinching, self-pierce riveting with semi tubular rivet or solid rivet. The most simple and cheapest technique is clinching. It based on dot-shaped embossing and extrusion of the joining parts. In case of self-pierce riveting with semi tubular rivet the joining parts are jointed by piercing the upper sheet metal with the rivet and by spread forming of the hollow part of the rivet in the lower metal sheet. In case of selfpierce riveting with a solid rivet both of joining parts are pierced by the solid rivet. After it material is pressed in a circular groove at the lower part of the rivet. The rivet is not plastically formed. In all cases one gets an undercut and a force-fit interconnection