Back-spray system and injection piston

Abstract

A back spray system comprising an injection piston having a plunger tip (26) and a shot rod (24) with a shot rod hole (32) drilled through the length of the rod connecting a lubricating supply to a collar (30) located right directly behind the plunger tip (24). The collar (30) has a predetermined number of collar holes (40) positioned circumferentially about the collar (30) sized and positioned to dispense a precise and uniform amount of lubricant to the space between the plunger tip (24) and the shot sleeve (20). Under the collar (30) is a channel with two drilled holes (38) connected to the shot rod hole (40).

1 . A back spray system for lubricating a shot sleeve of a die casting machine, comprising:
 a shot sleeve;   an injection piston having a plunger tip and a shot rod connected to said plunger tip;   a groove surrounding said shot rod; and   a collar surrounding said groove;   said shot rod having a shot rod hole through the length of said shot rod;   said groove having at least one groove hole connected to said shot rod hole;   said collar having a predetermined number of collar holes in communication with said groove and positioned circumferentially about said collar, and   lubricant, having been supplied to said shot rod hole, flowing through said at least one groove hole into said groove, and then being released from said groove through said collar holes to a space between said plunger tip and said shot sleeve.   
     
     
         2 . The back spray system according to  claim 1  wherein said collar has eight collar holes. 
     
     
         3 . The back spray system according to  claim 1  wherein said at least one groove hole comprises at least two groove holes. 
     
     
         4 . The back spray system according to  claim 1  wherein said collar is located behind said plunger tip. 
     
     
         5 . The back spray system according to  claim 1  wherein said lubricant is lubricating oil and is atomized with air. 
     
     
         6 . An injection piston used in combination with a shot sleeve, comprising:
 a plunger tip;   a shot rod connected to said plunger tip;   a groove surrounding said shot rod; and   a collar surrounding said groove;   said shot rod having a shot rod hole through the length of said shot rod;   said groove having at least one groove hole connected to said shot rod hole;   said collar having a predetermined number of collar holes in communication with said groove and positioned circumferentially about said collar, and   lubricant, having been supplied to said shot rod hole, flowing through said at least one groove hole into said groove, and then being released from said groove through said collar holes to a space between said plunger tip and said shot sleeve.   
     
     
         7 . The section piston according to  claim 6  wherein said collar has eight collar holes. 
     
     
         8 . The section piston according to  claim 6  wherein under said collar is a channel with at least two holes connected to said shot rod hole.