Rivet optimization and experimental research on the reshaping method

The application of conventional mechanical clinching in automotive industry is restricted because of the exterior protrusion. In order to reduce the protrusion height and increase the strength of clinched joint, a new rivet-reshaping process was proposed to reshape the clinched joint in this study. The rivet was embedded in the pit of the joint after the conventional mechanical clinching and then the protrusion was compressed to reduce the protrusion height. The maximum tensile strength of the clinched joint was obtained by finite element simulation using the software DEFORM-2D. The geometrical parameters of the reshaped rivet with maximum tensile strength were acquired by optimization using orthogonal design. In the experiment, the protrusion height of the reshaped joints was reduced from 1.6 to 1.1 mm. The average tensile strength of the reshaped joints was increased from 950.6 to 1 130.7 N, i.e. the average tensile strength was increased by 18.9% compared with the clinched joints before reshaping; and the average shear strength of the reshaped joints was increased from 1 168.6 to 2 636.1 N, i.e. the average shear strength was increased by 125.6% compared with the clinched joint before reshaping. It was proved that the reshaping method can reduce the protrusion height and increase the strength of clinched joint effectively.