Zero looseness fastener for linkage assembly

Abstract

A fastener is used to connect a first link to a second link in a vehicle seat assembly. The fastener has a head portion and a body portion extending outwardly from the head portion and defining an external diameter. The body portion is generally cylindrical and has a central bore with an internal diameter that is less than the external diameter. The method for connecting the first link to the second link with the fastener includes the steps of inserting the central body portion through aligned apertures in the links to form a subassembly and holding the subassembly fixed while a tooling member applies a linear load to the distal end of the body portion. The tooling member is inserted into the central bore and deforms the body portion for engagement with the first and second links to allow relative rotational movement between the links while eliminating relative linear movement therebetween.

We claim:  
     
         1 . A method for connecting a first link to a second link comprising the steps of 
 (1) providing a fastener having a head portion and a cylindrical body portion extending therefrom and terminating at a distal end, a first link having a first external surface, a first internal surface, and a first aperture extending therebetween, and a second link having a second external surface, a second internal surface, and a second aperture extending therebetween;    (2) aligning the first aperture with the second aperture;    (3) inserting the body portion of the fastener into the first and second apertures; and    (4) deforming the body portion into engagement with the first and second links to allow relative rotational movement between the links while eliminating free play.    
     
     
         2 . A method as recited in    claim 1    including the step of applying a longitudinal load to the distal end of the body portion to cause plastic deformation.  
     
     
         3 . A method as recited in    claim 1    including the steps of 
 providing the first link with a first thickness, the second link with a second thickness, and the body portion with a length that is greater than the sum of the first and second thicknesses prior to step (2);  
 holding the first internal face of the first link against the second internal face of the second link during step (2); and  
 inserting the body portion of the fastener through the first and second apertures such that the head portion engages the first external face of the first link while a segment of the body portion extends beyond the second external face of the second link during step (3).  
 
     
     
         4 . A method as recited in    claim 3    including the steps of applying the longitudinal load to the distal end of the body portion and causing the segment of the body portion that extends beyond the second link to bend transversely with respect to the longitudinal load to form a lip that partially engages the second external face of the second link during step (4).  
     
     
         5 . A method as recited in    claim 4    including the step of locking the second link to the fastener via the lip so that there is no relative rotational movement between the second link and the fastener while allowing the first link to move freely.  
     
     
         6 . A method as recited in    claim 1    including the steps of creating a subassembly comprised of the first link, the second link, and the fastener during step (3); 
 holding the subassembly fixed prior to step (4); and  
 moving a tooling member along a linear path toward the subassembly for engagement with the body portion to apply the longitudinal load.  
 
     
     
         7 . A method as recited in    claim 6    including the steps of providing the body portion with a central bore having a bore diameter and providing the tooling member with a extension having a diameter less than the bore diameter and having a curved exterior surface surrounding the extension; 
 inserting the extension into the bore such that the curved exterior surface engages the distal end of the body portion; and  
 deforming the distal end of the body portion by pressing the extension further into the bore causing the distal end to bend outwardly along the curved exterior surface of the tooling member to form a lip.  
 
     
     
         8 . A method as recited in    claim 1    including the steps of 
 providing the body portion with a generally uniform external diameter and a bore with a generally uniform bore diameter that is less than the external diameter; and  
 applying a longitudinal load to the body portion to increase the external and internal diameters, causing the body portion to engage the first and second links to hold the fastener firmly in place.  
 
     
     
         9 . A fastener for connecting a first member to a second member comprising: 
 a head portion; and    a body portion extending outwardly from said head portion and defining an external diameter, said body portion being generally cylindrical and having a central bore with an internal diameter that is less than the external diameter wherein said body portion is deformable for engagement with the first and second members to allow relative rotational movement between the members while eliminating relative linear movement therebetween.    
     
     
         10 . A fastener as recited in    claim 9    wherein said body portion is perpendicular to said head portion.  
     
     
         11 . A fastener as recited in    claim 9    wherein said head portion is circular.  
     
     
         12 . A fastener as recited in    claim 9    wherein said body portion terminates at a distal end, said distal end for receiving a longitudinal load for plastically deforming said body portion.  
     
     
         13 . A fastener as recited in    claim 12    wherein said longitudinal load causes said internal and external diameters to increase resulting in the body portion engaging the first and second members to hold the fastener firmly in place.  
     
     
         14 . A fastener as recited in    claim 12    wherein said distal end bends transversely to said longitudinal load and forms a lip for engaging one of the members.  
     
     
         15 . A fastener as recited in    claim 14    wherein said lip locks the fastener to one of the members via said lip to prevent relative rotational movement between the one member and the fastener while allowing the other member to move freely.  
     
     
         16 . A vehicle linkage assembly comprising: 
 a first link having a first external surface, a first internal surface, and a first aperture extending therebetween;    a second link having a second external surface, a second internal surface, and a second aperture extending therebetween;    a fastener having a head portion and a cylindrical body portion extending therefrom and terminating at a distal end wherein said body portion is inserted through said first and second apertures and plastically deformed to engage said first and second links to hold said fastener in place; and    said first and second links being movable to cause a seat to move.    
     
     
         17 . An assembly as recited in    claim 16    wherein said distal end of said body portion receives a linear load causing said body portion to plastically deform resulting in relative rotational movement between said first and second links while eliminating relative linear movement between said first and second links.  
     
     
         18 . An assembly as recited in    claim 17    wherein said first link has a first thickness, said second link has a second thickness, and said body portion has a length that is greater than the sum of the first and second thicknesses such that when said internal face of said first link is placed against said internal face of said second link and said body portion is inserted through said first and second links, a segment of said body portion extends beyond said links.  
     
     
         19 . An assembly as recited in    claim 18    wherein the linear load is applied to the distal end of the body portion causing said segment of said body portion to bend transversely with respect to the linear load, forming a lip for engaging the external surface of the second link.  
     
     
         20 . An assembly as recited in    claim 19    wherein said second link is locked to said fastener via said lip to prevent relative rotational movement between said second link and said fastener while allowing said first link to move freely.