Numerical Simulation And Experimental Study On Demoulding Of Semi-continuous Casting Of Aluminum Tube Based On Force Feedback

Aluminum tubes are usually large-diameter thick-walled aluminum tubes with a thick wall range of 5 ～ 100 mm and above by semi-continuously cast,widely used in ships,aerospace,national defense and other fields.It is a strategic material in aviation and national defense fields,can be used to make missile combustion chamber,ship hull and other parts.It has the advantages of high specific strength,light weight and good corrosion resistance.Semi-continuous casting has been successfully applied to copper tubes casting,which has the advantages of simple operation,energy saving and high efficiency.There are few studies on the preparation of aluminum tubes by this process.Especially with the increase of the thickness of the cast aluminum tube wall,the thermal-mechanical coupling effect of the inner and outer walls on the mold is more severe.Among them,the thermal-mechanical coupling effect of the inner wall of the aluminum tube on the core mold has a more serious impact on the casting process.The inner wall of the aluminum tube holds the core mold to cause the casting to stop,and the core mold fracture leads to the accident.In this thesis,the thermo-mechanical coupling effect between the tube blank and the mandrel during casting process is studied.The specific research contents are as follows.In order to solve the process window,simulate the casting process and detect the force of the billet during the casting process,the semi-continuous casting equipment for aluminum tube was designed,and then the important structural parameters of the equipment were optimized and the equipment was built and debugged.Based on the self-built equipment,the effects of casting process parameters on the temperature field,solidification field and thermal deformation of the tube billet were investigated,and the thermal-mechanical coupling behavior between the inner wall of the aluminum tube and the mandrel was revealed,which established the theoretical basis for the tube billet separation.In order to establish the control system of tube billet demoulding,the force analysis of the mandrel in different demoulding states was carried out,and the relationship between the axial force and the friction force of the mandrel under different demoulding states in the casting process was obtained.The force analysis of the aluminum tube in the actual casting process was carried out,and the demoulding state of the tube was judged by the force change of the mechanical sensor.Based on the above force analysis and the actual mechanical parameters test,the aluminum tube semi-continuous casting demoulding strategy is proposed,and the solution method of the mechanical sensor setting parameters in the actual demoulding process is given,which lays a foundation for successfully solving the problem of tube billet demoulding.In order to analyze the influence of process stability on the microstructure uniformity of tube billet,the microstructure of tube billet prepared by aluminum tube semi-continuous casting equipment was analyzed,and the influence of pouring stability on the surface quality and microstructure of tube billet was analyzed.In order to verify the effectiveness of the demoulding strategy,the above demoulding strategy was used for experiments and successfully demoulded.