Blind fastener and method of setting

Abstract

There is disclosed herein a method of connecting together at least two workpieces ( 30, 32 ) using a blind rivet ( 10 ), which comprises the steps of biasing a blind side end face of a blind rivet ( 10 ) against a workpiece ( 30 ) and subsequently effecting rotation ( 41 ) of the blind rivet ( 10 ) whilst in abutment with the workpiece ( 30 ) to create a heat weakened region of the workpiece through which the blind rivet ( 10 ) can subsequently be inserted by a biasing force less than a biasing force normally required to effect piercing of the workpiece ( 30, 32 ) by such a blind rivet ( 10 ).

1 . A method of connecting together at least two workpieces using a blind rivet comprising the steps of 
 positioning the at least two workpieces in abutment;    positioning a blind side end face of a blind rivet against a first one of said workpieces and applying a biasing force thereto to maintain said rivet in engagement with said workpiece;    rotating said rivet at a speed whilst maintaining said biasing force thereon;    utilizing said biasing force to drive said rotating blind rivet through the resultant heat weakened workpieces;    stopping rotation of said inserted rivet and setting said blind rivet to compress the workpieces between a deformed portion of the rivet body and a flange portion.    
   
   
       2 . A method as claimed in  claim 1  wherein said rivet is rotated at a speed of at least 200 rpm.  
   
   
       3 . A method as claimed in  claim 1  wherein said biasing force is determined to be less than that required to force the blind rivet through the non-weakened workpiece.  
   
   
       4 . A method as claimed in  claim 1  wherein said biasing force is between 2 kN and 10 kN.  
   
   
       5 . A method as claimed in  claim 4  wherein said biasing force is between 4 kN and 8 kN.  
   
   
       6 . A method as claimed in  claim 1  wherein said rivet is rotated at a speed of between 300 rpm and 1000 rpm.  
   
   
       7 . A method as claimed in  claim 1  using a blind rivet wherein said blind side end face comprises an abrasive surface.  
   
   
       8 . A method as claimed in  claim 1  using a blind rivet having a blind side end face with a workpiece engaging portion having a contact area less than the cross sectional area of the rivet.  
   
   
       9 . A method as claimed in  claim 8  using a blind rivet with a tapered or frusto-conical blind side end face.  
   
   
       10 . A method as claimed in  claim 1  wherein the step of rotating and setting the blind rivet is carried out using the same tool.  
   
   
       11 . A blind rivet for use in the method as claimed in  claim 1  having a parabolically curved blind side end face disposed co-axially with a longitudinal axis of said rivet.  
   
   
       12 . A blind rivet for use in the method as claimed in  claim 1  having a frusto-conical blind side end face disposed co-axially with a longitudinal axis of said rivet.  
   
   
       13 . A blind rivet as claimed in  claim 12  having an elongate cylindrical projection extending co-axially from said frusto-conical end face.  
   
   
       14 . A blind rivet as claimed in  claim 11  comprising an open ended rivet body and wherein said blind side end face is formed on a mandrel head extending beyond said rivet body.  
   
   
       15 . A blind rivet as claimed in  claim 11  comprising a closed end blind rivet wherein said blind side end face is formed on said closed end of said rivet body.  
   
   
       16 . A blind rivet as claimed in  claim 11  wherein said blind side end face is formed with an abrasive surface.  
   
   
       17 . A blind rivet as claimed in  claim 16  wherein said abrasive surface comprises a coating of abrasive material.  
   
   
       18 . A blind rivet comprising a workpiece engaging blind side end face, wherein said end face is provided with an abrasive surface.  
   
   
       19 . (canceled)