Patent ID: 6103993
Filing Date: 2000-08-15
Classification: B22D,B23K,B23P,F01D

Abstract:
A method of producing a blade for a turbo drive mechanism made from a metal alloy comprising:providing a casting mold,casting a molten metal alloy into said mold such that said alloy solidifies as a solid blade having an aerodynamic blade portion and a foot portion, the blade being formed with a hollow, internal space the molten metal solidifying in a longitudinal growth direction to form a columnar structure in said aerodynamic blade portion oriented in said longitudinal growth direction defining a plurality of longitudinal grain boundaries in said aerodynamic blade portion,incorporating means in said casting mold defining a narrow channel below said aerodynamic blade portion in which said molten metal alloy is constricted so that during formation of said columnar structure a large volume single crystal region is formed in said growth direction extending from said channel along the length of the cast blade such that said aerodynamic blade portion comprises said single crystal region integrated with said columnar structure, andlaser drilling in said single crystal region a series of holes extending through said blade to the hollow internal space, said series of holes being spaced longitudinally in said aerodynamic blade portion in said single crystal region and away from said grain boundaries of the columnar-structure in said aerodynamic portion.