Drawing–upsetting–extrusion–clinching of high-strength steel and aluminum alloy

Abstract

To realize good point connection between high-strength steel and aluminum alloy, a process of drawing–upsetting–extrusion–clinching was proposed. First, the sheets were drawn; then, the bottom of the protrusion part was extruded, forming the necessary initial interlock; and finally, the protrusion part was reverse press clinched, forming a certain height of the clinched head. Taking DP980 high-strength steel and Al5083 aluminum alloy as the connection objects and using the method of numerical simulation combined with experimental test, the mold was made, and the experiment was carried out on the basis of numerical simulation. The experimental results proved the feasibility of the process and the effectiveness of the numerical model. The simulation and experimental results show that the necessary interlock in the drawing–upsetting–extrusion stage is the premise of effective connection. The relative protrusion height should be around 55.6% after reverse-press-clinching. The best comprehensive mechanical properties measured by strength test were shear resistance of 2644 N, fatigue life of 24,535 times and peel resistance of 1522 N. Through failure analysis, the relationship between the interlock Tu and the neck thickness Tn of the joint with the best comprehensive mechanical properties was established as Tu = 0.35Tn. The design method of die and process parameters when the sheet thickness changes was researched by numerical simulation. The results show that the clearance between the punch and the die and the bottom thickness are directly proportional to the sheet thickness, and the drawing depth is directly proportional to the punch radius.