Impulse metalworking with vaporizing foil actuators

Abstract

Electrically driven rapid vaporization of thin metallic foils is used to conduct impulse-based metal working operations such as dynamic compaction of metal powders, collision welding, embossing, shearing, shape calibration, and closed-die forming. A metal body is sheared from a metal sheet using foil actuators operating at input electrical energies from 4 kJ to 10 kJ. During the impulse shearing operation, the sheared plugs were accelerated up to velocities of 1400 m/s within a few millimeters of travel distance. The sheared plugs were used as pistons to compress milled commercially pure titanium (CP-Ti) and Ti-6AI-4V alloy (Ti-6-4) powders, both of which had tap densities of approximately 25-28%. After the process, compaction in the range of greater than 90% was observed. When compared to a quasistatic cold compaction process, a significant gain in densification with same pressures was observed.

1 . A method for compacting a metal powder, comprising the steps of:
 generating an accelerated metal body; and   colliding the accelerated metal body into a mass of the metal powder, resulting in compaction of the metal powder.   
     
     
         2 . The method of  claim 1 , wherein:
 the colliding step occurs at a velocity in the range of 200 to 2000 m/s.   
     
     
         3 . The method of  claim 1 , wherein:
 the step of generating the accelerated metal body is achieved by the steps of:
 positioning a piece of sheet metal between a consumable metal body and a stationary body; 
 rapidly vaporizing the consumable metal body, directing vaporized metal into the piece of sheet metal; and 
 accelerating the piece of sheet metal into collision with the stationary body at a rate sufficient to shear off a portion of the piece of sheet metal. 
   
     
     
         4 . The method of  claim 3 , wherein:
 the stationary body is a die and the piece of sheet metal is deformed by the collision to shear off the accelerated metal body therefrom.   
     
     
         5 . The method of  claim 3 , wherein:
 the consumable metal body comprises a foil of aluminum.   
     
     
         6 . The method of  claim 3 , wherein:
 the rapid vaporizing is achieved by passing a high current rapidly into the consumable metal body.   
     
     
         7 . The method of  claim 6 , wherein
 the high current is achieved by discharging a bank of capacitors.   
     
     
         8 . The method of  claim 1 , wherein:
 the step of generating the accelerated metal body is achieved by the steps of:
 positioning a piece of sheet metal between a consumable metal body and a stationary body; 
 rapidly vaporizing the consumable metal body, directing vaporized metal into the piece of sheet metal; and 
 accelerating the piece of sheet metal into collision with the stationary body at a rate sufficient to shear off a portion of the piece of sheet metal. 
   
     
     
         9 . The method of  claim 3 , wherein:
 the stationary body is a die and the piece of sheet metal is deformed by the collision to shear off the accelerated metal body therefrom.   
     
     
         10 . The method of  claim 4 , wherein:
 the consumable metal body comprises a foil of aluminum.   
     
     
         11 . The method of  claim 8 , wherein:
 the consumable metal body comprises a foil of aluminum.   
     
     
         12 . The method of  claim 9 , wherein:
 the consumable metal body comprises a foil of aluminum.   
     
     
         13 . The method of  claim 4 , wherein:
 the rapid vaporizing is achieved by passing a high current rapidly into the consumable metal body.   
     
     
         14 . The method of  claim 10 , wherein:
 the rapid vaporizing is achieved by passing a high current rapidly into the consumable metal body.   
     
     
         15 . The method of  claim 8 , wherein:
 the rapid vaporizing is achieved by passing a high current rapidly into the consumable metal body.   
     
     
         16 . The method of  claim 11 , wherein:
 the rapid vaporizing is achieved by passing a high current rapidly into the consumable metal body.   
     
     
         17 . The method of  claim 9 , wherein:
 the rapid vaporizing is achieved by passing a high current rapidly into the consumable metal body.   
     
     
         18 . The method of  claim 12 , wherein:
 the rapid vaporizing is achieved by passing a high current rapidly into the consumable metal body.