Applications of Mold Filling Analysis in the Design of Centrifugal Casting Process for a Casting of Turbine Disc with Blades

摘要

In this study, a computer simulation system has been developed to analyze the fluid flow phenomena of molten superalloy in the casting assembly, where centrifugal casting incorporated with investment casting process is employed. The simulation system is then used to optimize the design of the casting process such as the runner design as well as the tilt angle between the casting assembly and the runner. The computer simulation system in this study incorporates two modules in a previously developed mold filling simulation system for casting. One is to calculate the amount of centrifugal force for all the locations in the casting assembly, which correspond to the rotation speed, tilt angle between the casting assembly and runner, and all other related designs and processing conditions of the casting process. The other is to incorporate the centrifugal force in the momentum equations in the mold filling simulation system. The developed system is then tested on a casting of turbine disc with 29 blades, which is centrifugally cast. The tilt angle between the casting assembly and runner has been found to have significant effects on the mold filling pattern. As the tilt angle is small, the filling pattern is seen to fill the blades on the bottom of the disc first and those on the top of the disc last. As the tilt angle becomes large, the filling pattern is changed to filling the blades on the top of the disc first and those on the bottom of the disc last. The optimal angle to obtain the most desired filling pattern is found to be with the gate perpendicular to the casting and a tilt angle of 20° between the runner and the casting.