(1) The process characteristics and heat transfer mode of iron mold sand coated casting are analyzed. Aiming at the common shrinkage cavity and porosity defects of castings, the data are searched to determine its formation mechanism and corresponding solutions. Based on the theory of equilibrium solidification and the solidification characteristics of iron mold sand coated casting, the feeding method and its application in the design of gating system are analyzed;
(2) The design rules of gating system of iron mold sand coated casting and ordinary sand mold casting are compared and analyzed. Combined with the characteristics of iron mold sand coated casting, the specific design method of gating system is studied. The effects of the shape and size of the sprue cup, sprue and runner, and the number of sprues on the filling process were studied;
(3) Taking the flywheel as an example, the model is established and the numerical simulation method is determined. Simulate the flow of molten iron and the change of temperature field during mold filling, and predict the possible shrinkage defects. The influence of different gating systems on the prediction results of different criteria is analyzed, and the solutions are put forward for improving the gating system;
(4) Different gating systems are designed respectively, and pouring experiments are carried out. The effects of different gating systems on possible casting defects are compared. Temperature measuring points are selected to measure the change of solidification cooling temperature of castings. Compared with the simulation results, the correctness of the gating system design is verified;
(5) The cooling process of nodular iron crankshaft was studied. The cooling curves of nodular cast iron crankshaft castings at different unpacking times were measured by experiments. The optimum unpacking time is determined by comparative analysis, and the possibility of realizing the stable production of as cast low alloy ductile iron crankshaft in actual production.