Method for clinching thick metal workpieces, use of a clinching tool, and steel structural element produced accordingly

A method of producing a load-bearing steel construction connection, wherein a clinch connection connecting a first metal workpiece with a second metal workpiece is formed by local deformation by means of a die tool and a counter-tool, comprising the steps of:

• placing one of the first or second metal workpieces on the other and aligning the first metal workpiece and the second metal workpiece on a processing surface of the counter-tool;
• advancing a die of the die tool;
• sinking the die into the two metal workpieces which are placed one on the other until the clinch connection is formed by local deformation;
• and
• withdrawing the die by use of a stripper so as to enable separation after clinching of the metal workpieces such that the stripper is advanced towards a surface of the first metal workpiece prior to the separation and that during the separation a separating force is exerted relative to the metal workpieces by means of the stripper while a return stroke force acting in an opposite direction draws the die back, wherein the separating force is less than 45 kN for a total workpiece thickness thicker than 8 millimeters,
• wherein the first metal workpiece has a first workpiece thickness and the second metal workpiece has a second workpiece thickness which together give a total workpiece thickness thicker than 8 millimeters,
• characterized in that the die is rotationally symmetrical with respect to a rotational axis and has at least two conically shaped transition regions which narrow at a flank angle in the direction of sinking in of the die, and the flank angle has a first angle portion of a lower transition region which leads into an end surface, and a second angle portion of an upper transition region, wherein the first angle is greater than the second angle, both first and second angle portions of the flank angle being greater than zero degrees, and that during the sinking the die upper transition region is at least partly sunk into the metal workpieces.