Simulation Analysis Of The Pneumatic Diameter Process And Buffer Design

As a kind of pipe size inspection equipment,pneumatic diameter machine has the characteristics of high diameter efficiency and clean energy.However,during the operation of the pneumatic diameter machine,on the one hand,it cannot directly reflect the pushing process of the nozzle airflow to the diameter stick;on the other hand,the fast outlet speed of the diameter stick will lead to the failure of the buffer,so that the cycle diameter cannot be completed.In order to better understand the inspection process of pneumatic diameter of steel pipe and ensure the normal operation of pneumatic diameter machine,the following work was carried out in this paper:(1)First,a two-dimensional axisymmetric model of aerodynamic diameter was prepared by using CFD software to simulate the process of the diameter stick moving from inside to outside the pipe.The results show that the airflow directly acts on the end face of the diameter stick after flowing out of the nozzle,and a part of the airflow was entering the annular gap and start to increase continuously.The airflow velocity reaches its maximum at the front end of the diameter stick.When the residual air was discharged from the pipe,a jet was appearing at the opposite end of the pipe for a period of time.Then,the influence degree of air pressure,diameter sticky mass and nozzle diameter on the speed of diameter stick movement were analyzed.The research results show that air pressure was the most influential degree on the speed of diameter gauge outlet.When it increases from 0.4MPa to 0.7MPa,the speed of outlet pipe increases by33% at most.When the diameter stick increased from 4kg to 7kg,the diameter stick of the gauge decreased by 20.8%.The nozzle diameter was little impact on the speed of the diameter stick,but mainly affects the smoothness of the starting motion of the diameter stick.(2)Considering the deviation of the diameter stick in the pipe,a three-dimensional aerodynamic diameter model was established to analyze the flow field distribution in different directions inside the pipe.The results show that in the direction of gravity,after the airflow flows out of the annular gap,a wall jet was formed along the wall surface of the steel tube,and two different eddies appear at the front end of the diameter stick.In the horizontal direction,the flow field at the front end of the gauge was symmetrically distributed in an umbrella structure.In the axial direction,the airflow starts to increase continuously after entering the annular clearance,and the airflow velocity reaches its maximum at the front end of the diameter stick.The pressure distribution on the surface of the diameter stick was gradually decreasing,and the pressure difference between the two ends was large,which was the main reason for the fast and unstable motion inside the diameter stick.(3)The original buffer was not ideal buffer effect,a cushioning scheme for the synchronous movement of spring and piston was proposed.The basic shape of the modified buffer was determined.Select 15m/s as the collision speed between the diameter stick and the buffer,the collision process between the diameter stick and two buffer were compared and analyzed in ANSYS Workbench software,it is found that the improved buffer was more sensitive to collision speed,the energy absorption efficiency were increased from 35% to 53%,indicating that the buffering effect were improved.At the same time,the diffusion process of the collision stress on the buffer panel during the collision was analyzed,and the maximum stress in the impact area of the buffer panel could reach 110 MPa and the maximum deformation was 5mm.The research work in this paper can provide a reference for the improvement and optimization of the pneumatic pipe diameter machine,which is of great significance to ensure the normal operation and use efficiency of the equipment.