| Annular forgings are the key basic components in nuclear power,petrochemical,shipbuilding,aviation and chemical industries.Such as aero engine,coal liquefaction reactor tube joint,hydrogenation reactor tube joint,missile launching shell and generator protection ring,its production quality is high.It is a bottleneck restricting the continuous development of heavy equipment manufacturing industry.Become the core of the major equipment manufacturing industry.The forging defects such as cracks and folding will make the mechanical properties of ring forging worse and seriously affect the quality of forgings.The heat transfer model of annular forging with cracks is studied.According to the heat transfer model,the abnormal change of the internal temperature field in the forging process is judged,the forging process is improved in time and effectively,the production of the defective products is avoided,the quality and precision of the forging is improved,and the theoretical support for the qualitative identification of the forgings is also provided.It is of great practical significance to improve the rate of qualified products and energy saving for forging.In this paper,a heat transfer model of hot annular forgings with transient heat transfer is proposed in this paper,which is based on the transient heat transfer,and the specific contents are as follows:Firstly,based on the heat transfer characteristics of micro-elements,the influences of high-temperature gas and thermophysical parameters in the crack region on the temperature field of the forgings are analyzed,the heat conduction differential equations satisfying the heat balance relationship of the micro-elements are derived,and the instantaneous heat flux is used as an intermediary variable,Correct the heat transfer coefficient and thermal conductivity.Secondly,based on the derivation of the heat balance equations,the forgings and the heat transfer differential equations of the fractures are established.The temperature field function of the cracks obtained is used as the definite solution condition for the heat transfer differential equations under the transient temperature field,combined with the internal and external environmental boundary conditions of the ring forgings,The naturalconvection boundary condition of cracks in finite space is used to establish the heat transfer model of a toroidal forging with thermal cracks based on transient heat transfer.The analytical solution of the heat transfer model is obtained by constructing auxiliary functions and separating variables.Finally,the finite element simulation software is used to simulate the heat transfer model of hot annular forgings with cracks,and the temperature field of the annular forgings with crack thermal state is obtained.In the experiment,the specimen is heated and the temperature of the outer surface is obtained by using the thermal imager.The error between simulation and experimental results is analyzed,and the feasibility of simulation analysis and heat transfer model is verified. |
