Research And Numerical Simulation Of Expanding Process Of Metal Shell (Head)

Along with the rapid development of domestic energy such as nuclear power and chemical industry,the product quality of pressure vessels requirements is increasing at the same time,and then for the product resistance stability and manufacturing difficulties of the current domestic convex head in the production process of manufacturing,this paper presents a new process for the overall bulge forming.Combined with the analysis of the experimental phenomena of metal bulging forming and the actual stress environment of its use conditions,the bulging process was developed in this paper.Putting the two pieces of circular plates with the same size overlapped,and meanwhile adding a certain amount of water into the clearance of these plates as an inflating medium.Placing the specimen in the heating furnace and along with the increasing temperature,the water evaporates into steam and generates pressure on the inner surface of the steel plate which makes the steel plate convex on both sides to come into being of the head body of the shell internal was completely closed.Using the way of the overall bulge forming process of high pressure,It could be produced into two heads with the same shape and size at one time.In the process of forming,the source of force was produced by the pressure in gas expansion,which has the same using environment with the head.The formed head has uniform stress distribution and Stable structure.In order to avoid the forming instability phenomena due to stress concentration which causes unnecessary security risks,the feasibility of technology need to be confirmed.Firstly finding the force vulnerabilities on the model through the theoretical calculation formula and its stress analysis of the geometric model of specimens bulging process,and using water vapor as inflating medium gas to calculated the bulging force in the condition of high temperature and high pressure in the confined space by the law of thermodynamics and gas properties of water vapor.Secondly,the head internal high pressure forming process was simulated.For the reason for unable to set the steam gasification in the finite element software,the internal energy of water vapor should be converted into pressure loading onto the inner surface of the metal shell,and its value will be affected by many variable factors of the water vapor temperature,Internal metal shell volume change and initial amount of water added,etc.In this paper,using the MATLAB compiler to secondary developed the DEFORM finite element software,and realized data exporting,external computing and data import substitution through iterative calculation method by solving the mutual restriction between the influencing factors.The law of metal plastic deformation was obtained by analysis the stress-strain distribution and influence factors of bulging forming into the simulation.Finally,through specifying the experiment scheme for the simulation parameters,the relative error was gotten by compared with the analysis the experimental results and simulation results.The full text utilized the simulation and experimental method completed the forming process of metal shell under internal pressure,and gotten the important parameters of the bulging process which will provide a certain reference to the head forming process.