Numerical Simulation And Process Optimization Of The Small High Pressure Vessel Head Forming Based On 20MnNiMo

20MnNiMo steel as a common low alloy high pressure vessel material widely used in many industrial process equipment, especially in the pressure vessel and radiation protection equipment, the use of occasions also relates to civil and national defense military and other fields. The forming process of high pressure vessel is mostly concentrated in large thick walled head at home and abroad, especially in the process of stamping and spinning.Therefore, the study of 20MnNiMo low alloy steel behavior in high pressure vessel forming process becomes a blind spot, urgent need of further research.Based on 20MnNiMo low alloy steel for small high pressure vessel head (diameter 218mm, thickness 9mm), using the hot stamping and hot forging two forming ways to research plastic forming theory, and extraction of thermal physical properties of new materials, and combining the finite element simulation of forming process to discover the best parameters within optimization process. The main research work of this paper are as follows: (1)Thermal properties of 20MnNiMo low alloy steel. Based on the thermal simulation compression test of the material, and the review of the current research status of 20MnNiMo, and the calculation of thermal properties of materials by JMatpro software, a series of related performance parameters are obtained and CAE software material database are Supplemented.(2) Numerical simulation of hot stamping for right head. Under the premise of thermal mechanical coupling, the stress and strain and temperature distribution in forming process were obtained and analysis, through spherical head model and parameters of high pressure vessel are established and sated in Deform-2d. Forming properties (thickness reduction, head closeness, and spring back) can also be evaluated.(3) Simulation of hot die forging process for left head. Based on the left head model and parameters of high pressure vessel are established and sated. Based on the establishment of the finite element system and the parameter setting for the left head in Deform-3d, the forming process is analyzed from four aspects of stress-strain, load, temperature field and material flow; The effect of parameters such as initial forging temperature on material flow, friction factor on top die wear and forming speed on forming load and the rules of stress and strain distribution, point tracking and metal flow in hot forging process of the head were concluded. The reasonable process parameters can also be obtained by combined with the experience and simulation experiments.(4) Optimization of forming process parameters of left head under orthogonal test design. Through the formulation of orthogonal test table, the maximum forming load of the left head and the deepest wear of the punch were studied, and the influence factors were analyzed by range and variance analysis. The reasonable process parameters can also be obtainedThe above research work can be summarized as:Two kinds of thermo mechanical coupling forming process simulation for small pressure vessels in 20MnNiMo low alloy steel; factors and levels of process parameters were analyzed; the deformation behavior of the plastic forming theory under thermal mechanical coupling is further verified. Through the analysis of the above parameters, the results can provide a good theoretical support for the die life and hemispherical head forming technology research.