Subsurface chills to improve railcar knuckle formation

Abstract

A method for manufacturing a railcar coupler knuckle includes, before casting, positioning an external chill within a cope mold portion and a drag mold portion offset from and adjacent internal walls of a pulling face and a throat of the cope and drag mold portions, thus producing a casting with reduced micro-shrinkage in at least the throat, a high-stress section of the casting. Use of subsurface chills produces an improved surface with fewer inclusions when compared to an equivalent surface produced in a process without use of a subsurface chill. The external chill may be a cone chill of a larger size to improve cooling and solidification at and below the surface. The external chill may also be a cylindrical and/or oblong chill with a tapered design that may correspond to the internal walls of the cope and drag mold portions between the pulling face and the throat.

1 . (canceled) 
     
     
         2 . An assembly for casting a light steel railcar coupler knuckle, comprising:
 a first mold portion, the first portion having internal walls defining at least in part perimeter boundaries of a coupler knuckle mold cavity including a front face portion, a nose portion, a pulling face portion, a heel portion, a throat portion, a tail portion, a lock shelf portion, and a locking face portion;   a second mold portion, the second mold portion having internal walls defining at least in part perimeter boundaries of a coupler knuckle mold cavity including a front face portion, a nose portion, a pulling face portion, a heel portion, a throat portion, a tail portion, a lock shelf portion, and a locking face portion;   at least one ingate;   at least one internal core placed to shape inside portions of the railcar coupler knuckle;   a first external chill portion positioned within the first mold portion, the first chill portion positioned between the front face portion and the tail portion of the first and second mold portions and adjacent to the throat portion and the C-10 pin hole, the first chill portion offset from and adjacent the internal walls of the pulling face and the throat of the first mold portion, wherein a wall of sand exists between the first chill portion and the internal walls of the coupler knuckle mold cavity;   a second external chill portion positioned within the second mold portion, the second chill portion positioned between the front face portion and the tail portion of the first and second mold portions and adjacent to the throat portion and the C-10 pin hole, the second chill portion offset from and adjacent the internal walls of the pulling face and the throat of the second mold portion, wherein a wall of sand exists between the first chill portion and the internal walls of the coupler knuckle mold cavity;   wherein the first and second chill portions are positioned within each of the first and second mold portions such that the chill portions overlay each other after the first and second mold portions are closed prior to casting.   
     
     
         3 . The assembly of  claim 2  further comprising at least one riser preceding and engaged with the at least one ingate. 
     
     
         4 . The assembly of  claim 2 , wherein a coupler knuckle is formable of metal from the first and second mold portions that include the chill portions, the coupler knuckle including an improved surface with reduced subsurface micro-shrinkage at a location of at least the throat of the coupler knuckle as compared to an equivalent surface cast in a process using a surface chill. 
     
     
         5 . The assembly of  claim 4 , wherein the improved surface extends substantially between the pulling face and lock shelf of the coupler knuckle. 
     
     
         6 . The assembly of  claim 2 , wherein the first and second external chill portions are a single integral piece. 
     
     
         7 . The assembly of  claim 2 , wherein the ingate is upstream of the throat portion and the C-10 pin hole. 
     
     
         8 . The assembly of  claim 2 , wherein the at least one internal core comprises two internal cores. 
     
     
         9 . The assembly of  claim 2 , wherein the at least one internal core comprises an internal core placed to define within the coupler knuckle a finger cavity. 
     
     
         10 . The assembly of  claim 2 , wherein the at least one internal core comprises an internal core placed to define within the coupler knuckle a pivot pin cavity and a kidney cavity. 
     
     
         11 . The assembly of  claim 2 , further comprising at least two internal cores, a first internal core placed to define within the coupler knuckle a finger cavity and pivot pin cavity and a second internal core placed to define within the coupler knuckle a kidney cavity. 
     
     
         12 . The assembly of  claim 2 , wherein the first and second chill portions each comprise a volume of at least ten cubic inches. 
     
     
         13 . The assembly of  claim 2 , wherein the first and second chill portions each comprise a mass of at least 3 pounds. 
     
     
         14 . An assembly for creating a mold for casting a light steel railcar coupler knuckle, comprising:
 a first pattern plate;   a second pattern plate;   a first pattern half attachable to the first pattern plate with which to form a first mold portion, the first pattern half having exterior walls defining in the first mold portion at least in part perimeter boundaries of a coupler knuckle mold cavity including a front face portion, a nose portion, a pulling face portion, a heel portion, a throat portion, a tail portion, a lock shelf portion, and a locking face portion;   a second pattern half attachable to the second pattern plate with which to form a second mold portion, the second pattern half having exterior walls defining in the second mold portion at least in part perimeter boundaries of a coupler knuckle mold cavity including a front face portion, a nose portion, a pulling face portion, a heel portion, a throat portion, a tail portion, a lock shelf portion, and a locking face portion;   at least one ingate;   a first external chill portion releasably attached to the first pattern plate positioned between the front face portion and the tail portion of the first pattern plate and adjacent to the throat portion and the C-10 pin hole, the first chill portion offset adjacent a throat region of respective pattern halves, wherein the first chill portion is configured to remain trapped within the first mold portion when the first pattern half is removed from the first mold portion;   a second external chill portion releasably attached to the second pattern plate positioned between the front face portion and the tail portion of the second pattern plate and adjacent to the throat portion and the C-10 pin hole, the second chill portion offset and adjacent a throat region of respective pattern halves, wherein the second chill portion is configured to remain trapped within the second mold portion when the second pattern half is removed from the second mold portion; and   wherein the first and second chill portions are attached to the first and second pattern plates such that the chill portions overlay each other after the first and second mold portions are closed prior to casting.   
     
     
         15 . The assembly of  claim 14  further comprising at least one riser preceding and engaged with the at least one ingate. 
     
     
         16 . The assembly of  claim 14 , wherein the ingate is upstream of the throat portion and the C-10 pin hole. 
     
     
         17 . The assembly of  claim 14 , wherein the first chill portion is releasably attached to the first pattern plate with one or more vertical pins and wherein the second chill portion is releasably attached to the second pattern plate with one or more vertical pins. 
     
     
         18 . The assembly of  claim 14 , wherein the first and second chill portions each include a larger cross-sectional area on a side that is mounted to the pattern plates than the cross-sectional area taken at any other height. 
     
     
         19 . The assembly of  claim 14 , wherein the first and second chill portions each comprise a volume of at least ten cubic inches. 
     
     
         20 . The assembly of  claim 14 , wherein the first and second chill portions each comprise a mass of at least 3 pounds. 
     
     
         21 . The assembly of  claim 14 , wherein the chill portions are comprised of one or more materials selected from the group consisting of: cast steel, cast gray iron, graphite, silicon carbide and a combination thereof. 
     
     
         22 . An assembly for casting a light steel railcar coupler knuckle, comprising:
 a first mold portion, the first portion having internal walls defining at least in part perimeter boundaries of a coupler knuckle mold cavity including a front face portion, a nose portion, a pulling face portion, a heel portion, a throat portion, a tail portion, a lock shelf portion, and a locking face portion;   a second mold portion, the second mold portion having internal walls defining at least in part perimeter boundaries of a coupler knuckle mold cavity including a front face portion, a nose portion, a pulling face portion, a heel portion, a throat portion, a tail portion, a lock shelf portion, and a locking face portion;   at least one ingate;   at least one riser preceding and engaged with the at least one ingate;   at least one internal core placed to shape inside portions of the railcar coupler knuckle;   a first external chill portion positioned within the first mold portion, the first chill portion positioned between the front face portion and the tail portion of the first and second mold portions and adjacent to the throat portion and the C-10 pin hole, the first chill portion offset from and adjacent the internal walls of the pulling face and the throat of the first mold portion, wherein a wall of sand exists between the first chill portion and the internal walls of the coupler knuckle mold cavity;   a second external chill portion positioned within the second mold portion, the second chill portion positioned between the front face portion and the tail portion of the first and second mold portions and adjacent to the throat portion and the C-10 pin hole, the second chill portion offset from and adjacent the internal walls of the pulling face and the throat of the second mold portion, wherein a wall of sand exists between the first chill portion and the internal walls of the coupler knuckle mold cavity;   wherein the ingate is upstream of the throat portion and the C-10 pin hole.