Pressure controlled fluid pressure extrusion method

Abstract

The lower part of a material to be molded forms a lower seal with a die. A punch applying a molding force to the material forms an upper seal with the perimeter of the die. The space between the upper and lower seals forms a pressure chamber that is filled with a fluid. As the punch descends into the die, the fluid is pressurized. The lower seal is a complete seal to prevent leakage of fluid into the die. The upper seal is given a clearance with the die that permits controlled leakage of fluid therepast at a rate that limits the maximum pressure in the pressure chamber while permitting the development of an adequate pressure on the material being molded.

What is claimed is:  
     
         1 . A pressure controlled fluid pressure extrusion method comprising: 
 placing a material to be molded in a die;    applying a fluid pressure to an outer perimeter surface of a material; and    pushing said material directly by a punch into said die for molding, whereby said material is molded into a desired shape.    
     
     
         2 . A pressure controlled fluid pressure extrusion method according to    claim 1   , wherein: 
 sealing said fluid by seals formed of contact between said material, said die, and said punch; and    the step of applying includes compressing and pressurizing said fluid by an action of said die and said punch.    
     
     
         3 . A pressure controlled fluid pressure extrusion method according to    claim 2   , wherein the step of applying includes adjusting a clearance between said die and said punch, said clearance controlling said fluid pressure.  
     
     
         4 . A pressure controlled fluid pressure extrusion method according to    claim 2   , wherein the step of sealing includes completely sealing between said material and said die, whereby leakage of said fluid therepast is completely prevented.  
     
     
         5 . A pressure controlled fluid pressure extrusion method according to    claim 4   , wherein the step of sealing includes providing a clearance between said punch and said die effective to permit leakage of said fluid therepast at a rate which produces the desired fluid pressure.  
     
     
         6 . A pressure controlled fluid pressure extrusion method comprising: 
 placing a material to be molded in a die;    completely sealing a lower portion of said material to said die;    adding a fluid to a space above said lower seal between a perimeter of said material an said die;    urging a punch into said die;    said punch forming an upper seal with said die;    a space between said lower portion and said upper seal being a pressure chamber;    advancing said punch into said die to mold said material into a product;    the step of advancing being effective to pressurize said fluid; and    providing a fit between said punch and said die at said upper seal that is effective to permit an amount of leakage that produces a desired level of fluid pressurization in said pressure chamber.