Numerical Simulation And Technology Optimization Of Centrifugal Casting Bimetal Composite Pipe

Pipeline is a key over-flow component used to transport sediment in river dredging engineering.In the course of it's work,due to the transportation of sand and stone under water,the wear is very serious and has strong corrosiveness,so it is required to have wear resistance on the inner surface of the pipeline and corrosion resistance.At the same time,the pipeline is required to have high strength and toughness because of the high pressure during transportation.Bimetallic composite pipe has become the developing direction of dredged pipe because of it's distinct difference in composition and performance between the inner layer and the outer layer,which can meet the requirements of comprehensive performance.Centrifugal casting method is ofen used for composite pipe,because of the complexity of casting conditions and process,the experimental cost of large-scale composite pipe is high,some parameters are difficult to test,and it is difficult to analyze the actual problems scientifically.Therefore,the numerical simulation analysis of the process has theoretical significance and practical value.In this paper,a large diameter thin-walled centrifugal casting bimetallic composite pipe is studied.According to the actual working conditions and working environment,304 stainless steel is selected as outer material and high chromium cast iron as inner material.The mathematical physical model of the composite pipe is established,and the process parameters,boundary conditions and latent heat of the composite pipe are analyzed.On this basis,using Flow-3D software as the simulation software,a reasonable simulation method is developed,and a small model is simulated to verify the reliability of the simulation method.The simulation of bimetallic composite pipe is divided into two stages: Firstly,simulating the filling process of the outer metal,so the temperature cooling curve is obtained,which can obtain the casting time interval of the inner and outer layer metal,the filling process of the inner layer metal is simulated.Then an orthogonal experiment method is adopted to analyzing the simulation result of the outer layer,three factors of temperature,rotation speed and casting speed are used as the research object,the filling time and the thickness of the fluid caused the temperature difference of the inner surface of the casting,which is recognized the judgment standard so that three-factor three-level orthogonal test table was established.Finally the optimized process parameter combinations were obtained by the analysis results.The casting process of inner layer metal was simulated successfully by undefined “restart” function in Flow-3D software.When the inner layer is simulated,the initial temperature of the outer metal is determined by calculation,then the initial temperature is brought into the temperature cooling curve of the outer metal to obtain the corresponding time interval.According to the interface bonding mechanism of bimetal pipe and the simulation results analyzed influence of binding quality,which is pouring time interval of inner or outer metal and casting temperature of inner layer metal to interface.