Powder pressing apparatus and powder pressing method

Abstract

A powder pressing apparatus comprises an upper punch and a lower punch for compression of a powder in a cavity formed in a through hole of a die. A gap between a side surface of the lower punch and a side surface of the through hole of the die is sealed by a sealing member. A lubricant is supplied with a gas from a nozzle in the side surface of the lower punch to the side surface of the through hole, and the lubricant applied to the side surface of the through hole is spread by an absorbing member. The cavity is filled with the powder while the cavity is under suction by a reduced pressure provided from the nozzle in the side surface of the lower punch. During the suction, a filtering member provides filtration for the lower punch not to draw the powder in.

What is claimed is:  
     
         1 . A powder pressing apparatus for formation of a compact by pressing a powder, comprising: 
 a die having a vertical through hole;    a first punch and a second punch, each being vertically movable within the through hole relative to the die, for compression of the powder within a cavity formed in the through hole; and    a supplying means including a supply port provided in a side surface of the first punch, for supply of a lubricant with a gas from the supply port to the side surface of the through hole within the through hole.    
     
     
         2 . The apparatus according to  claim 1 , further comprising an absorbing member provided in the side surface of the first punch for holding by absorption the lubricant applied to the side surface of the through hole and for contact to the side surface of the through hole within the through hole.  
     
     
         3 . The apparatus according to  claim 1 , wherein: 
 the first punch is formed to have a polyangular section so as to have an angled portion;    the supply port being formed near the angled portion of the first punch; and    the supplying means further including a lubricant supplying passage connected with the supply port, through the first punch for supply of the lubricant to the supply port.    
     
     
         4 . The apparatus according to  claim 1 , further comprising a sealing portion provided in the side surface of the first punch farther away from the cavity than is the supply port for sealing a gap between the side surface of the first punch and the side surface of the through hole.  
     
     
         5 . The apparatus according to one of claims  1  through  4 , wherein the first punch is a lower punch.  
     
     
         6 . The apparatus according to  claim 5 , wherein the lower punch has an upper surface formed into a recess.  
     
     
         7 . The apparatus according to one of claims  1  through  4 , wherein the powder includes a rare-earth magnetic powder.  
     
     
         8 . The apparatus according to one of claims  1  through  4 , wherein: 
 one of the first punch and the second punch is a lower punch; and  
 the apparatus further comprising a sucking means having a suction port provided in the side surface of the lower punch, for providing suction from the cavity under a reduced pressure from the suction port while the cavity is being filled with the powder.  
 
     
     
         9 . A powder pressing apparatus for formation of a compact by pressing a powder, comprising: 
 a die having a vertical through hole;    an upper punch and a lower punch, each being vertically movable within the through hole relative to the die, for compression of the powder within a cavity formed in the through hole; and    a sucking means including a suction port provided in a side surface of the lower punch, for providing suction from the cavity under a reduced pressure from the suction port while the cavity is being filled with the powder.    
     
     
         10 . The apparatus according to  claim 9 , further comprising a filtering member provided in the side surface of the lower punch for covering the suction port.  
     
     
         11 . The apparatus according to  claim 9 , wherein: 
 the lower punch is formed to have a polyangular section so as to have an angled portion;    the suction port being formed near the angled portion of the lower punch; and    the sucking means further including a suction passage connected with the suction port, through the lower punch.    
     
     
         12 . The apparatus according to  claim 9 , further comprising a sealing portion provided in the side surface of the lower punch below the suction port for sealing a gap between the side surface of the lower punch and a side surface of the through hole.  
     
     
         13 . The apparatus according to one of claims  9  through  12 , wherein the powder includes a rare-earth magnetic powder.  
     
     
         14 . A method of pressing a powder for formation of a compact through compression of the powder by a first punch and a second punch within a cavity formed in a vertical through hole of a die, comprising: 
 a lubricant supplying step of supplying a lubricant with a gas from a side surface of the first punch to a side surface of the through hole within the through hole;    a powder filling step of filling the cavity with the powder; and    a press forming step of forming the compact by pressing the powder filled in the cavity by the first punch and the second punch.    
     
     
         15 . The method according to  claim 14 , further comprising a step of spreading the lubricant applied to the side surface of the through hole.  
     
     
         16 . The method according to  claim 14 , wherein: 
 the first punch is formed to have a polyangular section so as to have an angled portion; and    the lubricant being supplied from inside the first punch through near the angled portion to the side surface of the through hole in the lubricant supplying step.    
     
     
         17 . The method according to  claim 14 , wherein: 
 a gap between the side surface of the first punch and the side surface of the through hole is sealed while the lubricant is supplied to the side surface of the through hole in the lubricant supplying step.    
     
     
         18 . The method according to one of claims  14  through  17 , wherein the first punch is a lower punch.  
     
     
         19 . The method according to  claim 18 , wherein the lower punch has an upper surface formed into a recess.  
     
     
         20 . The method according to one of claims  14  through  17 , wherein the powder includes a rare-earth magnetic powder.  
     
     
         21 . The method according to one of claims  14  through  17 , wherein: 
 one of the first punch and the second punch is a lower punch; and  
 the cavity being under suction by a reduced pressure provided from the side surface of the lower punch while the powder is being filled into the cavity in the powder filling step.  
 
     
     
         22 . A method of pressing a powder for formation of a compact through compression of the powder by an upper punch and a lower punch within a cavity formed in a vertical through hole of a die, comprising: 
 a powder filling step of filling the cavity with the powder while the cavity is under suction by a reduced pressure provided from a side surface of the lower punch; and    a press forming step of forming the compact by pressing the powder filled in the cavity by the upper punch and the lower punch.    
     
     
         23 . The method according to  claim 22 , wherein filtration is provided during the suction from the cavity by the reduced pressure for preventing the lower punch from sucking the powder in the powder filling step.  
     
     
         24 . The method according to  claim 22 , wherein 
 the lower punch is formed to have a polyangular portion so as to have an angled portion; and    the cavity being under suction by a reduced pressure provided from near the angled portion in the powder filling step.    
     
     
         25 . The method according to  claim 22 , wherein 
 a gap between the side surface of the lower punch and a side surface of the through hole is sealed while the cavity is under the suction by the reduced pressure in the powder filling step.    
     
     
         26 . The method according to one of claims  22  through  25 , wherein the powder includes a rare-earth magnetic powder.  
     
     
         27 . The method according to claims  26 , wherein the rare-earth magnetic powder is manufactured by a strip casting process.  
     
     
         28 . A powder pressing apparatus for formation of a compact by pressing a powder, comprising: 
 a die having a vertical through hole;    a first punch and a second punch, each being vertically movable within the through hole relative to the die, for compression of the powder within a cavity formed in the through hole;    a lubricant holding means provided in a side surface of the first punch, for application of a lubricant to a side surface of the through hole in contact with the side surface of the through hole,; and    a lubricant supplying means for supply of the lubricant to the lubricant holding means.    
     
     
         29 . The apparatus according to  claim 28 , wherein the powder includes a rare-earth magnetic powder.  
     
     
         30 . A method of pressing a powder for formation of a compact through compression of the powder by a first punch and a second punch within a cavity formed in a vertical through hole of a die, comprising: 
 a lubricant supplying step of supplying a lubricant to a side surface of the through hole by bringing a lubricant holding means holding the lubricant into contact with the side surface of the through hole;    a powder filling step of filling the cavity with the powder; and    a press forming step of forming the compact by pressing the powder filled in the cavity by the first punch and the second punch.    
     
     
         31 . The method according to claim  30 , wherein the powder includes a rare-earth magnetic powder.