Memory metal plug

Abstract

Memory metal plugs adapted to seal tubes are formed with a central post and laterally extended disks or rings. The plugs are formed from memory metal that is machined and heat treated to establish favorable temperature profile for the memory metal. The plugs are deformed in an apparatus that holds the plugs and cools the plugs to transform them into the martensitic state. A ram is used to force the cooled plugs through a die to decrease their diameter. These plugs can then be inserted into a tube and heated, causing them to return to their original state and thereby plug the tube.

1 . A method of swaging a memory metal plug, said plug having at least one laterally extended disk comprising 
 positioning said plug in contact with a die aligned with an opening in said die;    spraying a coolant onto said plug to convert said plug from an austenitic state to a martensitic state, forcing said plug through said die to deform said disks thereby decreasing the diameter of said plug.    
   
   
       2 . The method claimed in  claim 1  wherein said refrigerant is carbon dioxide.  
   
   
       3 . The method claimed in  claim 2  wherein said plug is held in a housing and a spacer is placed on said plug, and wherein said plug is forced through said die by forcing said spacer downwardly through said die.  
   
   
       4 . The method claimed in  claim 1  wherein said plug is held in said die and said refrigerant is sprayed through said die onto said plug.  
   
   
       5 . The method claimed in  claim 4  further comprising measuring the temperature of said die to determine the temperature of said plug and forcing said plug through said die when a predetermined temperature of said die is detected.  
   
   
       6 . An apparatus to swage a memory alloy plug, said plug having a plurality of laterally extended disks comprising 
 an annular die having an inlet opening, an upper untapered portion, and a lower tapered portion;    said upper portion adapted to support said memory metal plug;    a plurality of coolant inlets through said upper portion of said die; and    a ram adapted to force said plug from said upper portion of said die through said die.    
   
   
       7 . The apparatus claimed in  claim 6  wherein said coolant inlet comprises a plurality of orifices.  
   
   
       8 . The apparatus claimed in  claim 6  further comprising a thermocouple associated with said die said thermocouple associated with a second switch which controls aid ram.  
   
   
       9 . The apparatus claimed in  claim 7  comprising a first switch adapted to activate said ram to force said plug into an upper portion of said die and said second switch adapted to activate said ram to force said plug completely through said die.  
   
   
       10 . The apparatus claimed in  claim 8  further comprising a container adapted to catch a plug that has been forced through said die.  
   
   
       11 . The apparatus claimed in  claim 7  further comprising means to set a temperature where said second switch is activated by means of said thermocouple detecting said temperature.  
   
   
       12 . A memory metal plug having a central post and at least one disk extended radially outward from said post, a radiused portion between a juncture of said post and said disk extended around said post.  
   
   
       13 . The plug claimed in  claim 12  wherein said plug has a plurality of disks.  
   
   
       14 . The plug claimed in  claim 13  wherein each disk includes a first and second surface and wherein said radiused portion is at a juncture of said post and said first surface.  
   
   
       15 . The plug claimed in  claim 13  having a first disk and a second disk, said post extended from said first disk through said second disk, and wherein said radiused portion is at a junction of said rod and said second surface of said second disk.  
   
   
       16 . The plug claimed in  claim 12  having first, second and third disks, each disk having first and second surfaces, said plug having radiused portions at the junctures of said post and said first surface of said first disk, and at the junctures of said post and said first and second surfaces of said second disk.  
   
   
       17 . The plug claimed in  claim 12  wherein said radiused portion has a radium greater than about 0.015 inches.  
   
   
       18 . The plug claimed in  claim 17  wherein said radius is at least about 0.03 inches.  
   
   
       19 . A memory metal plug comprising a central post and at least one disk, said post having a tip extended out from a surface of said disk, a metallic heat conducting rod compression fitted to said tip.  
   
   
       20 . The plug claimed in  claim 19  wherein said metal rod is steel.