Fastener For Attachment By Friction Stir Processing

Abstract

A fastener is provided for attachment to a workpiece by a friction stir process. The fastener includes a base having an underside adapted to seat upon the workpiece and a fastener portion attached to the top side of the base. An anchor portion projects from the underside of the base and is adapted to be rotated and advanced at high speed and inserted into the workpiece by friction stirring of the workpiece. The anchor portion is embedded in the workpiece upon cooling of the workpiece. The anchor portion has an indent in the surface thereof enabling the softened stirred material to flow into the indent and thereby mechanically capture the anchor portion within the solidified workpiece.

1 - 12 . (canceled) 
     
     
         13 . A fastener for attachment to a workpiece, comprising:
 a base having an underside adapted to seat upon the workpiece, and a top side;   a fastener portion attached to the top side of the base;   an anchor ring of hollow cylindrical shape projecting from the underside of the base and adapted to be rotated and advanced at high speed and inserted into the workpiece upon friction stirring of the workpiece by the anchor ring,   said anchor ring having indented regions in which the friction stirred material of the workpiece becomes embedded to thereby anchor the anchor ring in the workpiece upon cooling of the workpiece;   
       in which the hollow cylindrical shape is defined by a plurality of annular segments having voids therebetween forming indents in which the friction stirred material of the workpiece becomes embedded to thereby anchor the anchor ring in the workpiece. 
     
     
         14 . A fastener for attachment to a workpiece, comprising:
 a base having an underside adapted to seat upon the workpiece, and a top side;   a fastener portion attached to the top side of the base;   an anchor ring of hollow cylindrical shape projecting from the underside of the base and adapted to be rotated and advanced at high speed and inserted into the workpiece upon friction stirring of the workpiece by the anchor ring,   said anchor ring having indented regions in which the friction stirred material of the workpiece becomes embedded to thereby anchor the anchor ring in the workpiece upon cooling of the workpiece;   
       in which the anchor ring is a hollow circular cylinder and a plurality of thickened axial extending pillars are arrayed around the hollow cylinder and the pillars define the indents. 
     
     
         15 - 19 . (canceled)