Mechanical properties of the two-steps clinched joint with a clinch-rivet

In the present study, mechanical properties of the two-steps clinched joint with a clinch-rivet were investigated. The two-steps clinching method includes two steps, mechanical clinching and upsetting with a clinch-rivet. The protrusion of the joint was upset to reduce the protrusion height with different upsetting forces. This method contributed to increase the strength and reduce the protrusion height of the clinched joint. Extensible dies were used to perform the mechanical clinching process, and a pair of flat dies was used to perform the upsetting process. AL6061 sheets were used to carry out the experiment. The upsetting forces were set to 25, 30, 35, 40 and 45 kN respectively to generate different two-steps clinched joints. Forming force, geometrical parameters, material flow and mechanical properties of the two-steps clinched joint were investigated by an experimental method. According to the achieved results, the cross-tension and tension-shearing strengths of the two-steps clinched joints with different upsetting forces were all higher than those of the conventional clinched joint. The strength of the two-steps clinched joint with an upsetting force of 35 kN was the highest of all. The average cross-tension strength of the two-steps clinched joints with an upsetting force of 35 kN was increased by 25% compared with the conventional clinched joints, while the average tension-shearing strength of the two-steps clinched joints was increased by 128%. The two-steps clinched joint could absorb more energy than the conventional clinched joint in the failure process. The two-steps clinching method was proved to be effective and reliable.