Self-locking end cap

Abstract

The present invention provides a self-locking end cap for closing an open end of a fiber tube. The self-locking end cap according to the invention includes a bottom wall, an integral tubular side wall that extends upwardly from the bottom wall to a top edge, and a plurality of barbs that project radially away from the tubular side wall. The top edge and the plurality of barbs are arranged to frictionally engage an inner surface of the fiber tube when the self-locking end cap is pressed into the open end of the fiber tube. The invention also provides a method of forming a container and a container formed according to the invention.

1 . A self-locking end cap for closing an open end of a fiber tube, the self-locking end cap comprising a bottom wall, an integral tubular side wall extending upwardly from the bottom wall to a top edge, and a plurality of barbs projecting radially away from the tubular side wall, wherein the top edge and the plurality of barbs are arranged to frictionally engage an inner surface of the fiber tube when the self-locking end cap is pressed into the open end of the fiber tube.  
   
   
       2 . The self-locking end cap according to  claim 1  wherein the plurality of barbs project radially away from the tubular side wall at points that are equidistant from each other.  
   
   
       3 . The self-locking end cap according to  claim 1  wherein the top edge is serrated.  
   
   
       4 . The self-locking end cap according to claim I wherein the plurality of barbs are arranged to project radially away from the tubular side wall in two or more rings that are generally parallel to each other and the top edge.  
   
   
       5 . The self-locking end cap according to  claim 4  wherein the barbs in a first ring are offset from the barbs in a second ring.  
   
   
       6 . The self-locking end cap according to  claim 1  wherein the self-locking end cap is formed of cold rolled drawn steel.  
   
   
       7 . The self-locking end cap according to  claim 1  wherein a portion of the tubular side wall proximate the top edge is fluted.  
   
   
       8 . A method of forming a container comprising: 
 providing a fiber tube having fiber wall and a first open end;    providing a first end cap having a bottom wall and an integral tubular side wall extending upwardly from the bottom wall to a top edge;    pressing the first end cap into the first open end of the fiber tube, bottom wall first, to close the first open end; and    forming at least one barb in the tubular side wall of the first end cap after the first end cap has been pressed into the first open end, the barb projecting radially from the tubular side wall and engaging an inner surface of the fiber wall.    
   
   
       9 . The method of forming a container according to  claim 8  wherein a plurality of barbs are formed in the tubular side wall of the end cap after the end cap has been pressed into the first open end.  
   
   
       10 . The method of forming a container according to  claim 9  wherein at least two of the plurality of barbs are formed simultaneously.  
   
   
       11 . The method of forming a container according to  claim 9  wherein each of the plurality of barbs is formed individually.  
   
   
       12 . The method of forming a container according to  claim 8  further comprising: 
 inserting matter into a cavity defined by the inner surface of the fiber tube and the bottom wall of the first end cap; and    pressing a second end cap into a second open end of the fiber tube to close the second open end.    
   
   
       13 . The method of forming a container according to  claim 12  further comprising: 
 forming at least one barb in a tubular side wall of the second end cap after the second end cap has been pressed into the second open end, the barb projecting radially from the tubular side wall and engaging the inner surface of the fiber wall.    
   
   
       14 . The method of forming a container according to  claim 8  wherein the barb extends to a point that pierces the inner surface of the fiber tube but does not extend completely through the fiber wall.  
   
   
       15 . A container formed according to the method of  claim 8 .  
   
   
       16 . A container comprising: 
 a fiber tube; and    an end cap disposed in an end of the fiber tube, the end cap having a bottom wall, an integral tubular side wall extending upwardly from the bottom wall to a top edge, and a plurality of barbs projecting radially from the tubular side wall and engaging an inner surface of the fiber tube.    
   
   
       17 . The container according to  claim 16  wherein the end cap is a self locking end cap and the plurality of barbs were formed in the tubular side wall of the end cap before the end cap is disposed in the end of the fiber tube.  
   
   
       18 . The container according to  claim 16  wherein at least a portion of the plurality of barbs were formed in the tubular side wall of the end cap after the end cap was disposed in the end of the fiber tube.  
   
   
       19 . The container according to  claim 18  wherein each of the plurality of barbs extend to a point that pierces the inner surface of the fiber tube but does not extend completely through a fiber wall of the fiber tube.