BLIND RIVET AND METHOD OF MAKING THE SAME

Disclosed is a self plugging blind rivet for securing together apertured members, the rivet comprising a tubular shell having a tail end face at one end and a preformed radially enlarged bead at the other end, and a stem that extends through the shell and has a stem head adjacent the tail end face of the shell and a breakneck located away from the stem head, in which the region of the stem shank on the stem head side of the breakneck has a plurality of depressions formed therein extending to the breakneck, the corresponding region of the shell substantially filling the depressions in a region adjacent the stem head and progressively less towards the breakneck whereby, in use and under axial compression loading of the shell, the shell preferentially buckles in the region adjacent the member remote from the preformed head to form a blind head in contact with the member so as to clamp together the apertured members. Also disclosed is a method of assembling the above-described rivet comprising inserting the shell in a die, the first part of which closely fits the outside diameter of the shell, a second part being formed as a taper and which progressively increases in diameter until it intersects a third pan of the die into which the tail end of the shell protrudes, supporting the head of the shell with an abutment inserting a punch which has a first diameter closely fitting the bore of the rivet shell and a second diameter which closely fits the third pan of the die, applying a compressive force between the punch and the abutment so as to compress the rivet shell to fill both the taper and the larger diameter of the die, removing the abutment and punch, inserting a stem and ejecting the assembled shell and stem through the die, whereby, during ejection, the material of the shell is forced into the depression in the stem to substantially fill the depressions at least at the tall end of the shell and progressively towards the breakneck.