Riser sleeve with air gap

Abstract

A riser sleeve ( 100 ) for use in a foundry molding operation has cylindrical body in which the side wall ( 14 ) that may be untapered or that may taper uniformly from the bottom to the top ( 12 ) of the body. The riser sleeve is characterized by a plurality of cavities ( 102 ) are formed on the side wall, extending from the top in an axial direction of the body. These cavities provide air gaps when the riser sleeve is inserted into a mold, decreasing heat loss at the interface between the riser sleeve and the mold.

1 . A riser sleeve for use in a foundry molding operation, the sleeve comprising:
 a body having a outside wall that extends from a bottom to a top of the body, and   a plurality of cavities formed on the outside wall, extending from the top in an axial direction of the body.   
     
     
         2 . The riser sleeve of  claim 1 , wherein the body is cylindrical. 
     
     
         3 . The riser sleeve of  claim 1 , wherein the body is frustoconical. 
     
     
         4 . The riser sleeve of  claim 2 , wherein each of the plurality of cavities is substantially semi-cylindrical, each cavity having an axis that is aligned along the outside wall. 
     
     
         5 . The riser sleeve of  claim 4 , wherein each cavity is characterized by a radius, such that the axes of adjacent cavities are spaced apart by a distance of at least four radii around the circumference of the riser sleeve. 
     
     
         6 . The riser sleeve of  claim 4 , wherein each cavity subtends an angle in the range of from about 120° to about 180°, as measured from the axis of the cavity. 
     
     
         7 . The riser sleeve of  claim 1 , wherein each cavity extends along the outside wall over at least a majority of a distance from the top towards the bottom, terminating above the bottom. 
     
     
         8 . The riser sleeve of  claim 1 , wherein the plurality of cavities are substantially uniformly spaced around a circumference of the body. 
     
     
         9 . The riser sleeve of  claim 1 , wherein the body is substantially hollow, with an interior wall or surface that corresponds in shape to the outside wall, less the plurality of cavities. 
     
     
         10 . The riser sleeve of  claim 3 , wherein the body has a diameter that decreases uniformly from the bottom to the top. 
     
     
         11 . The riser sleeve of  claim 3 , wherein each of the plurality of cavities is substantially semi-cylindrical, each cavity having an axis that is aligned along the outside wall. 
     
     
         12 . The riser sleeve of  claim 10 , wherein each of the plurality of cavities is substantially semi-cylindrical, each cavity having an axis that is aligned along the outside wall. 
     
     
         13 . The riser sleeve of  claim 11 , wherein each cavity is characterized by a radius, such that the axes of adjacent cavities are spaced apart by a distance of at least four radii around the circumference of the riser sleeve. 
     
     
         14 . The riser sleeve of  claim 12 , wherein each cavity is characterized by a radius, such that the axes of adjacent cavities are spaced apart by a distance of at least four radii around the circumference of the riser sleeve. 
     
     
         15 . The riser sleeve of  claim 12 , wherein each cavity subtends an angle in the range of from about 120° to about 180°, as measured from the axis of the cavity. 
     
     
         16 . The riser sleeve of  claim 12 , wherein each cavity extends along the outside wall over at least a majority of a distance from the top towards the bottom, terminating above the bottom. 
     
     
         17 . The riser sleeve of  claim 16 , wherein the plurality of cavities are substantially uniformly spaced around a circumference of the body. 
     
     
         18 . The riser sleeve of  claim 17 , wherein the body is substantially hollow, with an interior wall or surface that corresponds in shape to the outside wall, less the plurality of cavities.