Shot sleeve assembly with materials of different coefficients of thermal expansion

Abstract

A shot sleeve assembly for a die casting process includes a housing defining a bore open at both a front end and a rear end and a pour opening for receiving molten material, the housing includes a first coefficient of thermal expansion. A core is received within the bore and includes a second coefficient of thermal expansion lower than the first coefficient of thermal expansion. Front and rear covers attached to the housing hold the core in place within the bore and accommodate differences in thermal expansion between the housing and core.

What is claimed is: 
     
         1 . A shot sleeve assembly for a die casting process comprising:
 a housing defining a bore open at both a front end and a rear end and a pour opening for receiving molten material, the housing comprising a material of a first coefficient of thermal expansion;   a core received within the bore and extending from the front end to the rear end including a core opening aligned with the pour opening, the core comprising a material of a second coefficient of thermal expansion lower than the first coefficient of thermal expansion;   a front cover attached to the front end of the housing; and   a rear cover attached to the rear end of the housing, the rear cover forcing the core against the front cover holding the core within the bore of the housing.   
     
     
         2 . The shot sleeve assembly as recited in  claim 1 , wherein the rear cover comprises a nut threadingly received within the bore and rotatable to force the core against the front cover. 
     
     
         3 . The shot sleeve assembly as recited in  claim 1 , wherein the housing includes flats for holding rotation of the housing responsive to rotation of the rear cover. 
     
     
         4 . The shot sleeve assembly as recited in  claim 1 , wherein the front cover includes a shoulder against which the core abuts for holding the core within the bore. 
     
     
         5 . The shot sleeve assembly as recited in  claim 1 , including a plurality of fasteners extending through the front cover for securing the front cover to the front end of the housing. 
     
     
         6 . The shot sleeve assembly as recited in  claim 1 , wherein the front cover includes a plurality of threaded openings for receiving corresponding threaded fasteners for forcing the front cover from the housing. 
     
     
         7 . The shot sleeve assembly as recited in  claim 1 , including a key member disposed between the housing and the core for holding a position of the core relative to the housing. 
     
     
         8 . The shot Sleeve assembly as recited in claim I, wherein the core is fabricated from a refractory metal material. 
     
     
         9 . The shot sleeve assembly as recited in  claim 1 , wherein the core is fabricated form a ceramic material. 
     
     
         10 . A method of casting a cast article comprising:
 defining a mold cavity between at least two mold parts;   mounting a shot sleeve   heating a shot sleeve to a pre-heat temperature;   tightening a rear cover threadingly received within a housing to force a core disposed within the housing into a front cover;   pouring a quantity of molten material into the core through a pour opening in the housing;   forcing the molten material into the mold cavity; and   curing the molten material within the mold cavity.   
     
     
         11 . The method of casting a cast article as recited in  claim 10 , including loosening the rear cover prior to cooling the shot sleeve to room temperature that is less than the pre-heat temperature. 
     
     
         12 . The method of casting a cast article as recited in  claim 10 , comprising removing the front cover by inserting at least one threaded fastener through a threaded opening and threading the at least one fastener through the front cover and into engagement with a front end of the housing and forcing the front cover away from the housing by extending the threaded fastener from the front cover. 
     
     
         13 . The method of casting a cast article as recited in  claim 10 , wherein the core has a lower coefficient of thermal expansion than the housing. 
     
     
         14 . The method of casting a cast article as recited in  claim 10 , including extending a key through the housing against the core for preventing relative rotation between the core and the housing. 
     
     
         15 . A casting assembly comprising:
 a mold including at least one cavity for receiving molten material;   a shot sleeve mounted to the mold for injecting molten material into the cavity, the shot sleeve including a housing defining a bore open at both a front end and a rear end and a pour opening for receiving molten material, the housing comprising a material of a first coefficient of thermal expansion, a core received within the bore and extending from the front end to the rear end including a core opening aligned with the pour opening, the core comprising a material of a second coefficient of thermal expansion lower than the first coefficient of thermal expansion, a front cover attached to the front end of the housing, and a rear cover attached to the rear end of the housing, the rear cover forcing the core against the front cover holding the core within the bore of the housing; and   a plunger movable through the bore of the shot sleeve for forcing molten material through the core and into the at least one cavity.   
     
     
         16 . The casting assembly as recited in  claim 15 , wherein the rear cover comprises a nut threadingly received within the bore and rotatable to force the core against the front cover. 
     
     
         17 . The casting assembly as recited in  claim 15 , wherein the front cover includes a shoulder against which the core abuts for holding the core within the bore. 
     
     
         18 . The casting assembly as recited in  claim 15 , including a key member disposed between the housing and the core for holding a position of the core relative to the housing.