Patent ID: 6651727
Filing Date: 2003-11-25
Classification: B22D

Abstract:
In a die casting apparatus,a die having a part-forming die cavity having a volume VM; a shot tube having a bore with a diameter DT connected with the die cavity, and also having a pour opening at its rear for the introduction of molten metal, said shot tube having a shot tip reciprocatably carried within its bore between its rear end and its distal end to provide a shot stroke length of LT and an internal shot tube volume VT; a vent opening located a distance LV, equal to VM divided by VT times LT, from the distal end of the shot tube; first means for introducing a volume VM of molten metal through the pour opening and within the bore of the shot tube between the shot tip and the distal end of the shot tube; and second means for advancing the shot tip toward the distal end of the shot tube to force molten metal into the die cavity; said second means being operable to advance the shot tip at a rate forming a rising but non-turbulent wave of molten metal in front of the shot tip until it has traveled a distance about equal to LT-LV and to thereafter advance the shot tube at a rapid rate until the die cavity is filled with molten metal, and to exert extremely high pressure on the molten metal in the die cavity.