Patent ID: 7891924
Filing Date: 2011-02-22
Classification: B21J,F16B,Y10T

Abstract:
1. A low swage load fastening system adapted to secure a plurality of workpieces to one another, comprising: a pin member having an elongated pin shank adapted to be located in aligned openings formed within the workpieces, the pin member terminating at a first end in an enlarged head, which is adapted to engage a first surface of one of the workpieces, and at a second end in a grooved portion, which is adapted to extend past a second surface of another of the workpieces opposite the first surface, the grooved portion including a locking portion having a plurality of lock grooves defined by circumferentially extending pin grooves and associated pin shoulders terminating in pin crests, the locking portion having an outer diameter, the pin member further including a substantially straight pull portion extending from the second end of the pin member, the pull portion including a plurality of pull grooves; an installation tool including an anvil member having a swage cavity, and a collet; and a collar including a generally straight collar shank adapted to be swaged into the plurality of lock grooves of the pin member in response to a relative axial force or swage load applied between the pin member and the collar by the installation tool, thereby providing a desired magnitude of clamp load on the workpieces, the swage cavity of the installation tool being adapted to engage the collar shank of the collar and to swage it radially inward, the collar when swaged having collar grooves and collar shoulders that interlock with the pin grooves and the pin shoulders of the plurality of lock grooves of the pin member, the pin member being made from a first material and the collar being made from a second material, the first and second materials having corresponding ultimate shear stresses that are different from one another so that yielding of the pin member is substantially avoided upon swaging the collar thereto; wherein the collet includes a pull section having a plurality of teeth adapted to complimentarily engage the pull grooves of the pull portion of the pin member, and a protrusion which extends a length of the pull section in a direction towards the collar thereby to increase an area of contact between the collet and the anvil member, the protrusion forming a flat circular face ahead of and adjacent to a leading thread of the collet, and then a circular forwardly angled face ahead of the flat face, a second flat face, and an angular flat face back to a line of intersection with an outer diameter of the collet; wherein the plurality of lock grooves of the pin member include, a thread form defined by a plurality of radii for each of the pin grooves, the pin shoulders, and the pin crests of the lock grooves, the plurality of radii being blended in order to have a substantially smooth transition between each of the plurality of radii and thereby promote the complimentary interlocking engagement of the collar grooves of the collar with the lock grooves of the pin member when the collar is swaged, and to reduce the swage load required to swage the collar.