Numerical Simulation And Process Optimization Of Sand Casting For Dredging Pump Shell

Pump body is the core flow components of the dredging pump,the casting quality of which has a direct impact on service life and overall efficiency of the dredging pump.Compared with import,domestic pump body has many deficiencies,such as poor wear resistance,significant cavitation,low dimensional accuracy,frequent replacement and maintenance.How to significantly improve the casting quality of the pump body to increase its service life,has become one of the core technical problems that need to be solved in the domestic dredging industry.Therefore,it is crucial to use the numerical simulation software to calculate the casting process,optimize the casting process,eliminate the casting defects,and improve the casting quality of the dredging pump body.According to the basic theory of casting technology,the casting process of the structure of the casting dredging pump bodyhas been analyzed.Based on the results of analysis,bottom gating system and step gating system have beenput forward.In addition,the calculation of casting time and speed of the pump body,the determinationof the size of each runner in the two set of process,and the design of the pouring system of the pump body have been finished.The CREO,the GeoMESH and the MeshCAST software have been applicated in designing the dredging pump body,dividingthe finite element mesh and simulating the filling process of the two gating system respectively.By comparing two sets of process plan simulation results,it can be seen that temperature gradient distribution during the filling process of the bottom gating systemis disordered,and the temperature of the liquid metal is decreased greatly,which is easy to be oxidized and form shrinkage cavity.Yet the step gating system can provide a better temperature gradient distribution and a lower temperature decrease of molten metal.Therefore,the step gating system has been determinedfor casting dredging pump body ultimately.Thefeedingsystem and chilling systemof the casting dredging pump body have been designed.Then,the simulationsof temperature field and stress field in the solidification process of dredging pump bodyhave been completedby using software ProCAST.Moreover,besides of predicting the distribution of pump body defects during the casting process,the causes of the defects have been analyzed and the rationality of the feeding system and chilling system have beencomprehensive determined.Simulation results show that,due to the insufficient riser feeding distanceand the low feeding efficiency in the feeding system and unreasonablechilling block setting in the chilling system,the temperature of casting during solidification is random distribution,forming a multiple isolated liquid region,resulting in the shrinkage porosity and cavity during solidification process.By analyzing of the equivalent stress,deformation and hot cracking distribution of the dredging pumpduring solidification process,it is found that due to the difference in wall thickness between casting flange and pump pipe,producing temperature difference during solidification,there is a large deformation in the flange.According to the results of the simulation analysis,the process has been optimized,involving adjusting the design of ingate on the basis of the original,adding the chilling blocks and subsidies,using insulating riser and putting in insulating agent.Using ProCAST to simulate and analyze the optimized process again,it can effectively eliminate the casting defects,and significantly improve the casting quality.