Expandable fastener assembly with deformed collar

Abstract

At least one embodiment generally relates to an installation assembly for an opening in a workpiece that includes a swaged collar, an inner member, and an outer member. The swaged collar has a first end, a second end, and a main body extending between the first end and the second end. The main body includes an inner surface defining a passageway through the collar. The inner member has a mandrel section for expanding the outer member. The inner member is used to expand the outer member and to keep the outer member in an expanded state.

What is claimed is: 
     
         1 . A fastener assembly installable in an opening of a workpiece, comprising:
 a collar;   an outer member configured to be positioned in the opening, the outer member including a longitudinally-extending passageway, a coupling section, a head, and an expandable section between the coupling section and the head, the coupling section adapted to protrude from the workpiece and to be coupled to the collar; and   an inner member including a narrow section, a propping stem, and a mandrel section between the narrow section and the propping stem, the propping stem dimensioned and configured to prop the expandable section of the outer member after the mandrel section radially expands the expandable section in the opening of the workpiece to produce an interference fit between the outer member and the workpiece.   
     
     
         2 . The fastener assembly of  claim 1 , wherein the expandable section has an inner surface defining at least a portion of the longitudinally-extending passageway and an inner circumference, the inner circumference is less than an outer circumference of the propping stem. 
     
     
         3 . The fastener assembly of  claim 1 , wherein the inner member further includes a detachable shank and a decoupling feature between the detachable shank and the narrow section, the detachable shank separable from the narrow section at least proximate the decoupling feature when an axial load is applied to the detachable shank. 
     
     
         4 . The fastener assembly of  claim 1 , wherein the outer member is radially expandable from an initial configuration for placement in the opening of the workpiece to an expanded configuration to cold work the workpiece and to produce an interference fit with the workpiece. 
     
     
         5 . A method for fastening together a multi-component workpiece having an opening, the opening extending between a first side and a second side of the workpiece, the method comprising:
 positioning a hollow outer member in the opening;   moving a portion of an inner member on the second side of the workpiece within the hollow outer member, the inner member including a mandrel section;   radially expanding at least a portion of the outer member using the mandrel section of the inner member;   positioning a collar on the first side of the workpiece such that the collar surrounds the outer member; and   swaging the collar to deform the collar against the outer member.   
     
     
         6 . The method of  claim 5 , wherein radially expanding the portion of the outer member produces an interference fit with the workpiece. 
     
     
         7 . The method of  claim 5 , further comprising radially expanding the portion of the outer member while swaging the collar to deform the collar against the outer member. 
     
     
         8 . The method of  claim 5 , wherein the hollow outer member shields the opening of the workpiece from shear loads as the portion of the outer member is radially expanded to produce an interference fit between the outer member and the workpiece and/or induce fatigue enhancing compressive stresses in the workpiece. 
     
     
         9 . The method of  claim 5 , further comprising providing a clearance fit between the hollow outer member and the opening of the workpiece prior to radially expanding the portion of the outer member and the workpiece. 
     
     
         10 . The method of  claim 5 , wherein swaging the collar includes forming grooves lengthwise along an exterior of the collar. 
     
     
         11 . The method of  claim 5 , further comprising:
 coupling an installation apparatus on the first side of the workpiece to a detachable shank of the inner member protruding outwardly from the collar; and   moving a swaging assembly of the installation apparatus along the collar to form a plurality of elongate swage grooves along an exterior of the collar.   
     
     
         12 . The method of  claim 11 , further comprising separating the detachable shank from a propping stem of the inner member after moving the swaging assembly along the collar, wherein an interference fit is formed by the propping stem and the outer member. 
     
     
         13 . The method of  claim 5 , wherein swaging the collar includes deforming the collar using a plurality of ball bearings. 
     
     
         14 . The method of  claim 5 , wherein radially expanding the portion of the outer member includes radially expanding substantially all of an axial length of the outer member within the opening. 
     
     
         15 . The method of  claim 5 , further comprising:
 developing compressive stresses in the workpiece sufficient to alter fatigue performance of the workpiece by radially expanding the outer member in the opening.   
     
     
         16 . The method of  claim 5 , further comprising moving a propping section of the inner member into the radially expanded portion of the outer member. 
     
     
         17 . A swaging assembly for an installation apparatus, comprising:
 a housing having a first end, a second end, and a bore extending between the first end and the second end; and   an actuating device including a passageway and a plurality of spaced apart bearing elements surrounding the passageway, the actuating device movable through the bore towards the second end such that the bearing elements swage a collar of a fastener assembly protruding from a workpiece against which the swaging assembly is placed.   
     
     
         18 . The swaging assembly of  claim 17 , wherein the bearing elements are spherical bearings held by corresponding sockets in a sidewall of the actuating device. 
     
     
         19 . The swaging assembly of  claim 17 , wherein the bearing elements are adapted to produce corresponding grooves along an exterior of the collar. 
     
     
         20 . The swaging assembly of  claim 17 , wherein the actuating device includes a tubular member having an inner surface defining the passageway, the bearing elements protrude inwardly from the tubular member into the passageway. 
     
     
         21 . The swaging assembly of  claim 17 , wherein the plurality of bearing elements are circumferentially spaced from one another about the passageway. 
     
     
         22 . The swaging assembly of  claim 17 , wherein the actuating device extends from the first end of the housing and includes a biasing member, the biasing member is between the first end of the housing and an outwardly extending retainer of the actuating device to bias the actuating device away from the first end of the housing.