Isothermal shot tube assembly

Abstract

A shot tube assembly for a die casting process includes a spiral passage for circulating a coolant about a cavity containing the molten metal material. The circulating coolant provides temperature control of the shot tube that improves the casting process and increases shot tube life.

What is claimed is: 
     
         1 . A shot tube assembly for a die casting process comprising:
 an outer sleeve open at each end including an outer pour opening for receiving molten material;   an inner sleeve defining an core for molten material, the inner sleeve disposed within the outer sleeve and open at each end with an inner pour opening aligned with the outer pour opening;   a spiral passage encircling the inner cavity;   an inlet for communicating a coolant to the spiral passages; and   an outlet for exhausting coolant from the spiral passage.   
     
     
         2 . The shot tube assembly as recited in  claim 1 , wherein the outer sleeve includes an inner surface and the inner sleeve includes an outer surface and the spiral passage is at least partially defined by each of the inner and outer surfaces. 
     
     
         3 . The shot tube assembly as recited in  claim 2 , including flow disrupting features within the spiral passage for generating a turbulent flow in coolant flowing through the spiral passage. 
     
     
         4 . The shot tube assembly as recited in  claim 1 , wherein the inlet and outlet are disposed on a common end adjacent to the pour opening. 
     
     
         5 . The shot tube assembly as recited in  claim 1 , wherein the inlet and outlet comprise a plurality of inlets and a plurality of outlets. 
     
     
         6 . The shot tube assembly as recited in  claim 1 , including a fluid system for circulating coolant into the inlet and out of the outlet. 
     
     
         7 . The shot tube assembly as recited in  claim 1 , wherein the inner sleeve and the outer sleeve comprise a common material with a common coefficient of thermal expansion. 
     
     
         8 . The shot tube assembly as recited in  claim 1 , wherein the inner sleeve and the outer sleeve comprise different materials with different coefficients of thermal expansion. 
     
     
         9 . A shot tube assembly for a die casting process comprising:
 an outer sleeve open at each end including an outer pour opening for receiving molten material;   an inner sleeve defining an core for molten material, the inner sleeve disposed within the outer sleeve and open at each end with an inner pour opening aligned with the outer pour opening;   a coolant passage disposed about the inner cavity;   a flow disrupting feature within the coolant passage for generating a turbulent flow in coolant flowing through the coolant passage;   an inlet for communicating a coolant to the coolant passage; and   an outlet for exhausting coolant from the coolant passage.   
     
     
         10 . The shot tube assembly as recited in  claim 9 , wherein the outer sleeve includes an inner surface and the inner sleeve includes an outer surface and the coolant passage is at least partially defined by each of the inner and outer surfaces. 
     
     
         11 . A method of casting a cast article comprising:
 defining a mold cavity between at least two mold parts;   mounting a shot tube   maintaining a desired temperature of the shot tube by passing a liquid metal material through passages defined within the shot tube;   pouring a quantity of molten material into a core defined within the shot tube through a pour opening in the shot tube;   forcing the molten material into the mold cavity; and   curing the molten material within the mold cavity.   
     
     
         12 . The method of casting a cast article as recited in  claim 11 , wherein the shot tube includes an inner sleeve disposed within an inner sleeve with the passages defined between the inner sleeve and the outer sleeve and the liquid metal material circulates through the passages to maintain a desired temperature of the shot tube. 
     
     
         13 . The method of casting a cast article as recited in  claim 11 , including the step of cooling the shot tube with the liquid metal material to maintain the shot tube within a desired temperature range. 
     
     
         14 . A casting system comprising:
 a mold including at least one cavity for receiving molten material;   a shot tube including an outer sleeve open at each end including an outer pour opening for receiving molten material, an inner sleeve defining a core for molten material, the inner sleeve disposed within the outer sleeve and open at each end with an inner pour opening aligned with the outer pour opening, a spiral passage defined between the inner sleeve and the outer sleeve, an inlet for communicating a coolant to the spiral passage, and an outlet for exhausting coolant from the spiral passage; and   a plunger movable through the bore of the shot tube for forcing molten material through the inner cavity and into the at least one cavity.   
     
     
         15 . The casting system as recited in  claim 14 , wherein the outer sleeve includes an inner surface and the inner sleeve includes an outer surface and the spiral passage is at least partially defined by each of the inner and outer surfaces. 
     
     
         16 . The casting system as recited in  claim 14 , including a flow disrupting feature within the spiral passage for generating a turbulent flow in the coolant. 
     
     
         17 . The casting system as recited in  claim 14 , including a fluid system for circulating the coolant through the spiral passage of the shot tube. 
     
     
         18 . The casting system as recited in  claim 17 , wherein the coolant comprises a liquid metal material.