Calculation of riser for steel casting is more important than that for other alloy castings because of the high shrinkage and pouring temperature of cast steels, which leads to severe shrinkage defects.
Among the different calculation methods, the cubic equation method can be used to calculate the shape and dimensions of riser in parametric forms, but it is not widely used due to the large computational amount.
Numerical simulations of the solidification process of cast are more and more used in the design of casting process because of the economy of time and effort as well as the increased accuracy. Many researchers have studied the process of the flow and solidification processes of castings using ProCAST. Most of them, however, found the optimum values by constructing initial design schemes and repeating simulations and modifications. Also, the inclusion of excess mass in the riser is unavoidable, which reduces casting yield.
Hence, it is necessary to establish a methodology to determine the optimum size of the riser while saving the time for simulations.
Ri Hak Song, a researcher at the Faculty of Materials Science and Technology, has set the hydro-powered Pelton turbine blade casting as the main research project, and optimized the riser by combining the numerical simulation analysis by ProCAST with the cubic equation method.
He performed a calculation of the riser by the cubic method and a numerical simulation by ProCAST, a simulation tool for casting processes, to identify the most suitable riser.
The results of the study show that the yield of riser calculated by the cubic method does not differ significantly with the change in the shape of riser, but the elliptical shape is the optimum shape of the riser, with the ratio of height to width of 1.3 and the yield of riser of 67.5%.
...
