Abstract: In view of the failure phenomena such as fracture and pin hole damage often occur in the operation of the gear rail of the shearer， and in order to improve the mechanical performance of shearer rack casting and ensure the smooth progress of coal mining， it is necessary to conduct in-depth analysis on the casting and forming process of the rack cutters to find the optimal casting process plan.Taking the five-pitch rack as the research object， and the ProCAST software is used to numerically simulate the casting process of the rack casting.Through the analysis of the simulation results of the solidification process and the isolated liquid phase area of the rack casting， the position of shrinkage cavity defects after the solidification of the gear rail casting is predicted.The causes and effect of defects in rack casting are analyzed by causal analytical method of TRIZ theory.The optimization scheme of rack casting process-inclined casting process is put forward by means of object-field model innovation solution tool: inclined pattern modeling， when pouring， the sand box and the straight runner are not inclined； or keep the cavity in sync with the sand box and straight runner during pouring.The results show that the defects of shrinkage cavity in rack casting have been greatly improved， but the first scheme one is not conducive to molding， and increases the height of the sand box；The second scheme increases the erosion of the pouring sprue by the pouring liquid can easily cause sand inclusion.Combining with the advantages of the two process schemes， the final optimization scheme is obtained: the pattern is placed horizontally，the mold cavity and the sand box are inclined synchronously during pouring to keep the vertical runner straight.ProCAST software is used to simulate the optimized inclined pouring process and the results show that this scheme can keep rack rail castings from increasing the temperature gradient during the solidification process， effectively promote sequential solidification of rack rail castings， and improve the compactness of the structure， and the shrinkage defect is obviously improved.The volume of shrinkage cavity can be reduced from 2.2% to 0.052%.