Patent ID: 6325582
Filing Date: 2001-12-04
Classification: B21J,F16B

Abstract:
In a fastening system, including a two piece fastener, for securing a plurality of workpieces together with the fastening system having a required preselected magnitude of design shear load and a required preselected magnitude of design tensile load and with said two piece fastener optimized to meet said design shear and tensile loads with a minimum weight for the materials utilized, said fastener comprising:a pin member having an elongated shank including a smooth shank portion located in aligned openings in the workpieces and terminating in one end in an enlarged head and at its opposite end in a lock groove portion comprising a plurality of circumferentially extending lock grooves and associated lock groove shoulders, said smooth shank portion being of a preselected length relative to the combined thickness of the workpieces such that said lock groove portion will extend outwardly from the aligned openings, said smooth shank portion being of a diameter sufficient to provide the necessary shear strength to accept said design shear load,a tubular collar having a collar shank portion adapted to be swaged into said lock grooves whereby the workpieces are fastened together, said collar shank portion being of a preselected length sufficient to overlay and to be swaged into said lock grooves, said collar shank portion when swaged into said lock grooves having collar grooves and shoulders interlocking said lock grooves and lock groove shoulders, said pin member and said collar being of different materials having ultimate shear stresses of different magnitudes with the ratio of such shear stresses of said pin member to said collar being such that crushing of said pin member in swage is substantially avoided,said collar shank portion having a minimum average wall thickness, and hence weight,said collar shank portion having an outer surface having a circumferentially extending wave like contour with a plurality of waves defined by arcuate crests and arcuate roots smoothly connected, said outer surface being formed with between around 8 to around 16 waves,said collar shank portion adapted to be swaged into said pin lock grooves via a swage anvil having an effective throat swage portion,said collar shank portion having a predetermined volume of material which is between around 18% to no greater than around 20% greater than the available volume defined by said effective throat swage portion and the confronting portion of said pin lock grooves into which said collar is swaged,said predetermined volume of material and said waves contoured and selected to provide a reduced load required for swage while providing said required preselected design tensile and shear loads.