Fastener with proportioned strength lock grooves

Abstract

A new fastener having stiffness proportioned and/or strength proportioned lock grooves to enable predetermined load distribution across the lock grooves.

What is claimed is: 
     
       1. A fastener having a head and a shank portion, and a swage collar member .Iadd.adapted to be .Iaddend.fastened thereon for holding workpieces, said fastener having .Iadd.a plurality of .Iaddend.at least three .Iadd.each of .Iaddend.differently proportioned strength locking annular shoulder and groove means .Iadd.alternatingly arranged along the shank portion .Iaddend.for providing a predetermined desired load distribution across the shank portion which .Iadd.load distribution .Iaddend.is generally coextensive with the collar to the sheet line of the .[.workpiece.]. .Iadd.workpieces.Iaddend., said plurality of locking shoulder .Iadd.means .Iaddend.and groove means being non-uniform in dimensions and wherein, .Iadd.said collar when swaged onto said shank substantially fills said at least three groove means, .Iaddend.   each of said groove means increases in size .Iadd.in both axial and radial dimensions .Iaddend.as distance from the sheet line increases .Iadd.with the resultant shear areas of said groove means increasing substantially in size from the sheet line .Iaddend.and, .Iadd.   each of said shoulder means increase substantially in size in an axial direction as distance from the sheet line increases .Iadd.whereby the resultant shear areas of said shoulder means similarly substantially increase.Iaddend., and   said shoulder .Iadd.means .Iaddend.and groove means provide proportioned stiffness such that the .Iadd.said .Iaddend.shoulder .Iadd.means .Iaddend.and groove means fail at approximately the same load to thereby provide the maximum strength for the fastener and being operative to prevent shear stress from being taken up at only a shoulder which is closely adjacent to the sheet line.   
     
     
       2. The invention of claim 1 wherein, the .Iadd.said .Iaddend.shoulder .Iadd.means shear area .Iaddend.and groove .Iadd.means .Iaddend.shear area between the shank and collar is divided proportionately in relation with their respective strengths to give proportioned .Iadd.strength and .Iaddend.stiffness .[.lock grooves.].  .Iadd.for said locking groove means and said shoulder means .Iaddend.across the axial length of the collar. 
     
     
       3. The invention of claim 1 wherein, the .[.shoulders.]. .Iadd.said shoulder means .Iaddend.are tilted toward the workpiece line to increase the effective strength of the fastener. .[.4. The invention of claim 1 wherein, each of said shoulder means increases in size as distance from 
     
     
        the sheet line increases..]. 5. The invention of claim 1 wherein, said fastener includes a shoulder and/or groove shear area relationship that is proportioned in a predetermined desired manner, and said proportioned strength shoulder .Iadd.means .Iaddend.and .Iadd.said .Iaddend.groove 
     
     
        means are significantly non-uniform in dimension. 6. The invention of 
     
     
        claim 1 wherein, the shank shoulders are designed to fail first. 7. The invention of claim 1 wherein .Iadd.shoulders are formed on said collar when said collar is swaged onto said shank portion and .Iaddend.the collar shoulders are designed to fail first. .Iadd. 8. A fastener having a head and a shank portion, and a swage collar member adapted to be fastened thereon for holding workpieces, said fastener having a plurality of at least three each of differently proportioned strength locking annular shoulder means and groove means alternatingly arranged along the shank portion for providing a predetermined desired tension load distribution axially across the shank portion which tension load distribution is generally coextensive with the collar to the sheet line of the workpieces, said plurality of locking shoulder means and groove means being non-uniform in dimensions and wherein, said collar when swaged onto said shank portion substantially fills said at least three groove means,   each of said differently proportioned shoulder means has a shear area which increases substantially in size as the distance from the sheet line increases.   each of said groove means having at least an axial dimension which increases substantially in size as distance from the sheet line increases, said increasing size groove means being operative to substantially increase the shear areas on said collar as the distance from the sheet line increases, and said shear area of said shoulder means and said shear areas of said collar being proportioned to each other in relation to their respective shear strengths,   said shoulder means and groove means being operative to provide proportioned stiffness and said proportioned strength such that the said shoulder means and groove means fail at approximately the same tension load to thereby provide the maximum strength for the fastener and being further operative to prevent shear stress from being taken up at only a   
     
     
        shoulder which is closely adjacent to the sheet line. .Iadd.9.  A fastener having a head and a shank portion, and a swage collar member, adapted to be fastened thereon for holding workpieces, said fastener having a plurality of at least three each of differently proportioned strength locking annular shoulder means and groove means alternatingly arranged along the shank portion for across the shank portion which load distribution is generally coextensive with the collar to the sheet line of the workpiece, successive one of said plurality of locking shoulder means being non-uniform in axial dimensions and successive ones of said plurality of locking groove means being non-uniform in axial dimensions and wherein, said collar when swaged onto said shank portion substantially fills said at least three groove means,   each of said groove means increases substantially in size as distance from the sheet line increases whereby the resultant shear areas of said groove means similarly substantially increase and,   said shoulder means and groove means being dimensioned so as to provide proportioned stiffness such that the said shoulder means and groove means fail at approximately the same load, said proportioned stiffness and proportioned strength of said locking annular shoulder means and groove means cooperating to thereby provide the maximum strength for the fastener and being operative to prevent shear stress from being taken up at only a shoulder which is closely adjacent to the sheet line. .Iadd. 10. A fastener having a head and a shank portion, and a swage collar member adapted to be fastened thereon for holding workpieces,   said fastener having a plurality of at least three each of differently proportioned strength locking annular shoulder means and groove means alternatingly arranged along the shank portion for providing a predetermined desired load distribution across the shank portion which load distribution is generally coextensive with the collar to the sheet line of the workpieces, said plurality of locking shoulder means and groove means being non-uniform in dimensions and wherein, said collar when swaged onto said shank substantially fills said at least three groove means,   each of said groove means increases substantially in axial length and therefore size as distance from the sheet line increases whereby the resultant shear areas on said collar when swaged substantially increase with the increase in said axial length and,   each of said shoulder means having a substantially increasing axial thickness as the distance from the sheet line increases, whereby the resultant shear areas of said shoulder means similarly substantially increase and   said shoulder means and groove means provide proportioned stiffness such that the said shoulder and groove means fail at approximately the same tension load to thereby provide the maximum strength for the fastener and being operative to prevent shear stress resulting from said tension load from being taken up at only a shoulder which is closely adjacent to the sheet line. .Iaddend.