Research On Influence Of Magnet Geometry On High Frequency Induction Welding Of Longitudinal Seam Welded Pipes

With the development of the world economy,the demand for oil and gas resources continues to increase.The exploitation and long-distance transportation of deep-sea oil and gas are inseparable from high-quality large-diameter pipes.In order to improve the output and welding quality of welded pipes,it is necessary to deeply understand the principle of electromagnetic heating and study the factors that have a significant influence on the electromagnetic field and temperature field distribution on the pipe during the welding process.As a key part of the impedance concentrator,the magnetic flux has a significant influence on the welding effect.Under the premise of an in-depth understanding of the process and principle of high-frequency induction welding for producing longitudinally welded pipes,numerical simulation of the high-frequency induction welding of longitudinally welded pipes under the action of a magnetic conductor is carried out in ANSYS finite element simulation software.The content involved mainly includes:The welding model was established in ANSYS finite element software,and relevant material properties were assigned according to the actual situation.The meshing method based on "linear gradient" and "area division" was proposed for the complex model with large element size span,and a good mesh was obtained;The APDL language is used to realize the magnetic-thermal "double-cycle" coupling calculation based on the physical environment method,and the electromagnetic field and temperature field distribution at the weld are obtained,and the position offset phenomenon and the weld at the outer surface of the tube blank weld at the maximum magnetic induction intensity are analyzed.The "Y"-shaped distribution of the magnetic induction intensity on the joint surface points out the "hyperbolic" distribution of the temperature field in the middle of the wall thickness on the cross section of the weld and the "hourglass" distribution on the entire wall thickness.Investigate the influence of different magnetic field distribution methods on the electromagnetic field and temperature field in the welding process.Through quantitative analysis,it is found that increasing the cross-sectional area of the magnet bar and reducing the distance between the magnet bar and the inner surface of the tube blank will increase the magnetic induction intensity and current density at the welding seam,and increase the welding efficiency.Strengthen the magnetic resistance ability,thereby effectively improving the welding efficiency.The influence of the spatial distribution parameters of the array magnets on the distribution of the magneto-heat path on the tube during the welding process is studied,and the influence of the main spatial distribution parameters of the magnets on the magneto-heat distribution and welding efficiency is obtained.Design a temperature measurement experiment program for the induction welding of a longitudinally welded pipe under the action of a magnetic conductor,process and assemble the experimental device,and conduct a temperature measurement experiment.The experimental data is compared with the simulation data under the corresponding conditions to verify the accuracy of the numerical simulation results.