Integrated Study Of Tube Cutting And Expending Process For Tubular Heat Exchanger

The tubular heat exchanger occupy an important position in chemical,energy,nuclear,marine and many other industrial production,and their forming quality is directly related to the energy efficiency and service life of the whole system.The joint between the heat exchanger tube and the plate bore(referred to as the joint)is the most prone to failure in the entire installation.Mechanical expansion forming is commonly used in the manufacture of smaller diameter and wall thickness heat exchangers because of its simple structure,ease of operation and low expansion cost.In actual production,mechanical expansion and forming require the heat exchanger to undergo the tube flaring process,the cutting process and the partial mechanical expansion process in sequence.The cutting process often has a certain impact on the sealing performance of the tube plate expansion process at the joints due to unreasonable selection of the processing parameters,resulting in the need for additional partial mechanical expansion processes,which increases the cost of man-hours and reduces production efficiency.Therefore,research on the mechanical expansion and forming process is of great value to the production of heat exchangers.In this paper,the mechanical tube plate expansion,cutting and partial mechanical expansion process of tubular heat exchanger is studied by using finite element simulation and experimental methods,mainly as follows:(1)In this paper,based on the theory of elasto-plasticity mechanics,a numerical analysis of the tube plate expansion process of the heat exchanger tube is carried out,and a finite element model of the tube plate expansion process in the mechanical expansion forming process is established in combination with the actual processing.The influence of the maximum shape of the tube expansion tool and the surface roughness of the tube expansion tool on the forming quality of the tube plate expansion process is analysed.The magnitude and distribution of residual contact stresses at the joint is studied.The accuracy of the finite element model is verified in conjunction with theoretical calculations.Suitable processing parameters are determined according to the quality evaluation index of the expanding tube to pave the way for the subsequent analysis of the cutting process.(2)Finite element numerical simulation was used to study the effect of machining parameters on the sealing performance of the joint during the cutting process.The cutting forces during the process are analysed,the magnitude and distribution of residual contact stress at the joint after the completion of the cutting process and the trend of change are investigated to find out the influence of the machining parameters of the cutting process on the sealing performance formed by the tube cutting process,and the accuracy of the model is verified through experiments.(3)Proposes an Integrated forming device for cutting and expanding processes that integrates multiple processes into a single process and optimises the mechanical expansion process.The machining process of the expansion tube assembly was analysed using finite element numerical simulation.A linear regression model is used to analyse the relationship between the outer diameter of the heat exchanger tube and the tube expansion torque during the tube expansion process.The validity of the model is verified by comparing the model predictions with the actual values,in conjunction with actual production experience.Provides theoretical guidance for the selection of parameters for the partial mechanical expansion process.