Blind rivet and method of assembly

Abstract

A blind rivet and a method of assembly comprising a tubular shell and mandrel in combination. The mandrel comprises a stem and a radially-enlarged head which in use forms a blind head to the shell to set the rivet, in which either the head of the mandrel or the bore of the shell is formed with a plurality of depressions the bases of which lie on a notional circle having a diameter which, where the depressions are formed in the head of the mandrel, is less than the bore of the shell or, where the depressions are formed in the bore of the shell, is greater than the diameter of the head of the mandrel. The depressions, which are preferably generally longitudinally disposed, define ribs, ridges or other protrusions therebetween which in use and on pulling the mandrel into the shell bore extend radially beyond the bore of the shell, so that material of the shell becomes displaced by contact with the ridges and occupies the depressions. The invention may be applied either to pull-through, or self-plugging rivets.

1 . A blind rivet comprising a tubular shell and mandrel in combination, the mandrel comprising a stem and a radially-enlarged head which in use forms a blind head to the shell to set the rivet, in which the head of the mandrel is formed with a plurality of depressions the bases of which lie on a notional circle having a diameter which is less then the bore of the shell and which define protrusions which extend radially beyond the bore of the shell.  
   
   
       2 . A blind rivet according to  claim 1 , in which the depressions are generally longitudinally disposed and have a major component parallel with the axis of the rivet.  
   
   
       3 . A blind rivet according to  claim 1  or  2 , in which the material of the mandrel, or at least the head thereof, is harder than the material of the shell.  
   
   
       4 . A blind rivet according to  claim 3 , in which the leading edge of the protrusions is provided with a chamfer to form an annular angled segmented shoulder between the stem and head of the mandrel.  
   
   
       5 . A blind rivet according to  claim 3 , in which the depressions are in the form of grooves or channels which are disposed in a frusto-helical disposition relative to the axis of the mandrel.  
   
   
       6 . A blind rivet according to  claim 3 , in which two or more shells are carried on a common mandrel.  
   
   
       7 . A blind rivet according to  claim 3 , which has been set whereby the bore of the shell carries radial projections formed by passage therethrough of the head of the mandrel.  
   
   
       8 . (canceled)  
   
   
       9 . (canceled)  
   
   
       10 . A method of setting a blind rivet in apertured members, the method comprising the steps of applying through the apertures a rivet tubular shell having a pre-formed radial head so that the head is adjacent one of said member and drawing though the shell a mandrel comprising a stem and a radially-enlarged head to form a blind head to the shell adjacent the other of said members, in which the head of the mandrel is formed with a plurality of depressions defining protrusions the bases of which lie on a notional circle having a diameter which is less than the bore of the shell and which extend radially beyond the bore of the shell, whereby, on drawing the mandrel through the shell, the protrusions displace material from the shell to occupy the depressions.