Blind rivet

Abstract

A blind rivet formed with a tubular shell, and a mandrel extending through the shell. The shell has an outwardly extending flange at one end forming a rivet head, and having a first set of radial indentations arranged around the periphery of the shell at a first distance from the rivet head, and a second set of radial indentations arranged around the periphery of the shell at a second distance from the rivet head. Each of the radial indentations are formed by crimping them in the rivet shell after the shell has been positioned around the mandrel with the end of the shell remote from the rivet head defining the blind end of the rivet shell. Lastly, the mandrel having a head formed at one end to abut against the blind end of the shell, and the stem extending from the head having a point of weakness part way along the length thereof disposed within the shell.

What is claimed is:  
     
         1 . A blind rivet comprising 
 a. a tubular shell;    b. a mandrel extending through the shell;    c. the shell has an outwardly extending flange at one end forming a rivet head, and having a first set of radial indentations arranged around the periphery of the shell at a first distance from the rivet head, and a second set of radial indentations arranged around the periphery of the shell at a second distance from the rivet head, the radial indentations having been formed by crimping into the rivet shell after it is positioned around the mandrel; the end of the shell that is remote from the rivet head being the blind end of the rivet shell; and    d. the mandrel having a head at one end which abuts against the blind end of the shell, and a stem extending from the head, the stem having a point of weakness part way along its length, and disposed within the shell.    
     
     
         2 . The combination claimed in  claim 1  wherein: 
 a. a third set of indentations arranged around the periphery of the shell at a third distance from the rivet head.  
 
     
     
         3 . The combination claimed in  claim 2  wherein: 
 a. the hardness of the rivet shell in the region of each of the indentations is between 20% to 30% higher than the hardness of the rivet shell at a point mid way between adjacent longitudinally spaced indentations.  
 
     
     
         4 . The combination claimed in  claim 3  wherein: 
 a. the depth of at least one of the sets of the indentations, prior to the rivet setting process, is at least 0.20 mm.  
 
     
     
         5 . The combination claimed in  claim 4  wherein: 
 a. the depth of at least one of the sets of the indentations, prior to the rivet setting process, is at least 20to 25% of the thickness of the shell.  
 
     
     
         6 . The combination claimed in  claim 5  wherein: 
 a. each set of radial indentations having between two to eight indentations.  
 
     
     
         7 . The combination claimed in  claim 6  wherein: 
 a. the longitudinal spacing between adjacent sets of indentations is at least 2 mm.  
 
     
     
         8 . The combination claimed in  claim 7  wherein: 
 a. the radial indentations are circular with outwardly sloping edges.  
 
     
     
         9 . The combination claimed in  claim 8  wherein: 
 a. the first and second set of indentations in the shell are respectively nearer to, and further from, the shell flange, than the point of weakness of the mandrel is to the shell flange.  
 
     
     
         10 . A method of securing at least two workpiece components together using a blind rivet comprising the steps of: 
 a. positioning the blind rivet such that the mandrel of the blind rivet extends through substantially aligned apertures in the workpiece components; and    b. moving the mandrel axially relative to the shell such that the head of the mandrel abuts against the blind end of the shell, thereby causing the portions of the shell between the indentations to expand radially, and the radial indentations in the shell to collapse, whereby the workpiece components are held together and the apertures in the workpiece components are substantially filled.    
     
     
         11 . The method claimed in  claim 10  comprising the additional step of: 
 a. using a soft material of predetermined density for at least one of the workpiece components.  
 
     
     
         12 . The method claimed in  claim 10  comprising the additional step of: 
 a. Using a friable material of predetermined density for at least one of the workpiece components.  
 
     
     
         13 . The combination claimed in  claim 9  wherein: 
 a. an aperture formed in each of the workpiece components; and  
 b. the apertures aligned with each other.  
 
     
     
         14 . The combination claimed in  claim 13  wherein: 
 a. one of the workpiece components is formed of a soft material of predetermined density.  
 
     
     
         15 . The combination claimed in  claim 13  wherein: 
 a. at least one of the workpiece components is formed of a friable material of predetermined density.