Expanding head riveting method

In the method of securing a metallic rivet to work containing a through bore, and first and second counterbores;, said second counterbore being frusto-conical and tapering forwardly between the first counterbore and the bore, the rivet having a head at one side of the work, and an axially extending shank extending through the bore, the shank having a terminal protruding at the opposite side of the work, the rivet head having an end face defining a ring-shaped dome extending about the rivet axis and in substantial alignment with the outer surface of the shank, the steps that include

• a. seating the rivet head against the work second counterbore while maintaining only slight annular clearance between the work first counterbore and the rivet head, and with the shank then extending through the bore,
• b. expanding the rivet head radially outwardly to tightly engage the work first counterbore, said expansion of the rivet head being effected by applying force to said ring-shaped dome to flatten said dome and
• c. maintaining the head substantially confined within the first and second counterbores during said radial expansion.