Study On The Control Technique Of Upsetting Deformation For Welding Of Rails

The technology of rail welding plays an important role in the engineering of laying continuous welded railway (CWR). With the rapid development of high-speed and heavy-loading track, the material of rails should have better ultimate tensile strength and wear resistance. The weldability of rails becomes poorer for the higher ultimate tensile strength and larger rail size. Optimal welding temperature field and upsetting deformation can be implemented by controlling welding process and welding parameters, and high quality welding joints of rails can be gotten, which is significant to ensure the quality of track engineering and reduce or eliminate the hidden troubles of traffic safety.In this paper, the temperature field for gas pressure welding of rails is simulated using the ANSYS finite element program; tests of the upsetting deformation process for rail welding are done on the Gleeble-2000 simulation machine. Based on the above, welding parameters are detected by developing a special data acquisition system for the digital rail gas pressure welding machine. The influences on welding quality of rails resulting from the control mode of upsetting pressure is studied and a new control technique of rail welding quality by realizing the control of constant upsetting length and transformation upsetting speed is put forward.The results show that the three-dimensional (3-D) finite element temperature field model in this paper can describe the dynamic temperature distribution of gas pressure welding of rails, which is useful for optimizing the size of welding-flame nozzle and selecting appropriate welding parameters; the calculating of upsetting length should include the length change during the heating stage, and the welded joints are excellent if the value of upsetting length is controlled between 35mm and 40mm; the rail welding defects will be reduced or eliminated when the new control technique of constant upsetting length and transformation upsetting speed is adopted on the control system of the exiting rail welding set.