Molding of die-cast product and method of

Abstract

A system and method of preventing surface imperfections of die-cast products with the method comprising the steps of loading a volume of molten zinc from a source of molten zinc into a chamber of a dispenser station, dispensing the molten zinc from the dispenser station through a hot runner and into a mold cavity, continually maintaining the molten zinc in a molten state from the source of molten zinc to the mold cavity, interrupting the flow of the molten zinc to the mold cavity, following the contraction of the molten zinc in the mold cavity as the molten zinc solidifies therein; and removing the solidified die-cast zinc product from the mold cavity.

1 . A system for die-casting products with reduced surface imperfections comprising:
 a source of molten zinc;   a dispenser station having a molten zinc chamber and a piston for loading and dispensing molten zinc from the dispenser station;   a mold cover continually maintaining the molten zinc supported therein in a molten state;   a hot runner for transferring the molten zinc from the dispenser station to the mold cover;   a mold housing mateable with the mold cover to define a mold cavity therein for receiving the molten zinc, the mold cover having a pathway connecting the hot runner to the mold cavity;   an actuating pin located in the pathway of the mold cover for controlling access of the molten zinc to the mold cavity and for following the contraction of the solidification of molten zinc in the mold cavity without intensifying the pressure of the molten zinc in the mold cavity; and   a thermal-insulating barrier located between the mold housing and the mold cover to thermally isolate the temperature difference between the mold housing and the mold cover to enable the zinc in the mold cavity to solidify while the zinc in the mold cover remains in a molten state.   
   
   
       2 . The system of  claim 1  wherein in use the mold cover, hot runner, dispenser station, and source of molten zinc continually maintain the molten zinc supported therein in a slushy state. 
   
   
       3 . The system of  claim 1  including a mold passage for venting air from the mold cavity as the mold cavity receives the molten metal and an ejection pin for removing a solidified die-cast zinc product from the mold housing. 
   
   
       4 . The system of  claim 1  wherein in use the dispenser station, the hot runner, and the mold cover continually maintains a temperature therein at or above 420° C. 
   
   
       5 . The system of  claim 1  including a control system for controlling the operations of the dispenser station and the mold station. 
   
   
       6 . The system of  claim 1  including a finishing station for applying a finishing surface treatment on the solidified die-cast zinc product. 
   
   
       7 . A method of improving the surface properties and preventing surface imperfections and cracking of die-cast products comprising the steps of:
 loading a volume of molten metal into a chamber of a dispenser station;   dispensing the molten metal from the chamber of the dispenser station through a hot runner and into a mold cavity defined by a mold housing and a mold cover;   continually maintaining the molten metal in a molten state from the source of molten metal to the mold cavity;   interrupting the flow of the molten metal to the mold cavity;   following the contraction of the molten metal in the mold cavity by maintaining sufficient pressure on the molten metal as the molten metal solidifies therein without intensifying the pressure of the molten metal to inhibit formation of air bubbles; and   removing a solidified die-cast product from the mold cavity of the mold station.   
   
   
       8 . The method of  claim 7  including the step of applying a finishing surface treatment on the solidified die-cast product. 
   
   
       9 . The method of  claim 7  wherein the step of removing the solidified die-cast product from the mold cavity comprises using an ejection pin located on the mold housing to remove the solidified die-cast product from the mold cavity. 
   
   
       10 . The method of  claim 7  wherein the step of loading the volume of molten metal from the source of molten metal into the chamber of the dispenser station and dispensing the molten metal from the chamber of the dispenser station comprises using a pressure cylinder to load the volume of molten metal from the source of molten metal into the chamber of the dispenser station and using the pressure cylinder to dispense the molten metal from the chamber of the dispenser station. 
   
   
       11 . The method of  claim 7  wherein the step of loading the volume of molten metal comprises loading a volume of molten zinc, molten magnesium, molten aluminum, molten tin or an alloy thereof. 
   
   
       12 . The method of  claim 7  wherein the step of continually maintaining the molten metal in a molten state comprises continually maintaining the molten metal in a slushy state from the source of molten metal to the mold cavity. 
   
   
       13 . The method of  claim 7  wherein the step of continually maintaining the molten metal in a molten state from the source of molten metal to the mold cavity comprises continually maintaining the temperature within the dispenser station, the hot runner, and the mold cover above 420° C. 
   
   
       14 . The method of  claim 7  including the step of maintaining the temperature of the actuating pin above 420° C. 
   
   
       15 . The method of  claim 7  including the step of placing a thermal-insulating barrier between the mold housing and the mold cover to thermally isolate the temperature difference between the mold housing and the mold cover. 
   
   
       16 . The method of  claim 7  including the step of venting air inside the mold cavity through a mold passage as the mold cavity receives the molten metal. 
   
   
       17 . A method of inhibiting or preventing surface imperfections and cracking of die-cast zinc products comprising the steps of:
 continually maintaining a shot of molten zinc in a molten state from a source of molten zinc to a mold cavity;   temporarily closing off an access of the shot of molten zinc to the mold cavity;   maintaining sufficient pressure on the shot of molten zinc in the mold cavity without intensifying the pressure of the molten zinc in the mold cavity to inhibit formation of air bubbles therein; and   removing a solidified die-cast zinc product from the mold cavity.   
   
   
       18 . The method of  claim 17  wherein the step of continually maintaining the shot of molten zinc in a molten state comprises continually maintaining the shot of molten zinc in a slushy state from the source of molten zinc to the mold cavity. 
   
   
       19 . The method of  claim 17  including the step of applying a finishing surface treatment on the solidified die-cast product. 
   
   
       20 . The method of  claim 18  wherein the step of continually maintaining the shot of molten zinc in a molten state from the source of molten zinc to the mold cavity comprises continually maintaining the temperature of the shot of molten zinc above 420° C. 
   
   
       21 . The method of  claim 20  wherein the step of applying a finishing surface comprises electroplating a bubble free coating on the solidified die-cast product