Patent ID: 7996977

Claim:
A method of forming a connecting eyelet for a stack arrangement ( 11 ) having a first plate-shaped workpiece ( 12 ) and at least one another plate-shaped workpiece ( 13 ) following the first plate-shaped workpiece ( 12 ) the first plate-shaped workpiece ( 12 ) and the at least one another plate-shaped workpiece ( 13 ) being connectable by the eyelet ( 14 ; 34 ), the method comprising the steps of: embossing a fracture zone ( 22 ) in the at least one another workpiece ( 13 ) at a backside thereof ( 21 ) remote from the first plate-shaped work-piece ( 12 ); thereafter, forming with a piercing die ( 25 ), in a single movement, a through-opening ( 23 ) in the first workpiece ( 12 ) and a through-opening ( 15 ) in the at least one another workpiece ( 13 ), with the through-opening ( 23 ) in the first workpiece ( 12 ) having a cross-section smaller than a cross-section of the eyelet ( 14 ; 34 ) and with the through-opening ( 15 ) in the at least one another workpiece ( 13 ) having a cross-section greater than the cross-section of the eyelet ( 14 ; 34 ), the cross-section of the through-opening ( 15 ) in the at least one another workpiece being defined by the fracture zone ( 22 ); finally, drawing, with a plunging die ( 26 ) displaceable through the stack ( 10 ) substantially perpendicular thereto, material of the first workpiece ( 12 ) through the through-opening ( 15 ) in the at least one another workpiece ( 13 ) for forming the connecting eyelet ( 14 ), with a free space, which is defined by a difference between the cross-section of the through-opening ( 23 ) in the first plate-shaped workpiece ( 12 ) and the cross-section of the through-opening ( 15 ) in the at least one another plate-shaped workpiece ( 13 ), being formed between a rim ( 17 ) of the through-opening ( 15 ) in the at least one another plate-shaped workpiece ( 13 ) and an outer profile of the connecting eyelet ( 14 ).