Investigation on mechanical behavior of clinched joints produced with dissimilar dies

Abstract

The advantages of well-distributed material flow, easy demolding, and good mechanical interlock structure of the extensible die provide the possibility to be widely used in joining lightweight components. In order to explore the differences in the mechanical properties of the joints produced by different dies, the mechanical behavior of the clinched joints made by the fixed die and extensible dies of 2, 3, and 4 movable segments was investigated in the present study. The process of forming evolution, geometric characterization, failure mode, static strength, joint stiffness, and energy absorption of the dissimilar joints were studied by experimental method. In the clinching process, the neck thickness of joints made by extensible dies can be enlarged by the sliding outward of the movable segments compared with those produced by fixed dies. The failure mode of all clinched joints in this paper is neck fracture. The clinched joints produced by extensible dies of 3 movable segments have the highest static strength in both static tensile and shear tests among the dissimilar joints, which values are 1239.41 and 1259.80 N, respectively. Shearing strength of the joints performed by the extensible dies with 2, 3, and 4 movable segments was increased by 9.84%, 10.09%, and 9.40%, and the tensile strength of those clinched joints was increased by 16.27%, 20.31%, and 14.34% than that of the joints produced by the fixed dies. Experimental have proved that the number of movable segments on the extensible dies has a limited effect on the joint stiffness, tensile strength, and energy absorption of the clinched joints in the cross-lap-tensile test, while it has great effect on the stiffness and energy absorption of the clinched joints in the single-lap-shear test.

Investigation of the flat clinch–rivet process with different blank holder structures

“…21 To increase strength and improve the material flow of the clinched joints, much research has focused on the proper selection and optimization of forming tools and process parameters. 22,23 Lambiase 24 used experimental and numerical analysis to investigate forming tool design in clinching processes with extensible dies. The results showed that using a larger diameter punch and die or reducing the depth of the die increased the value of the neck thickness.…”