The cause of distortion defect and its improvement process of the point rail quenching by medium frequency induction heating power supply

The switch rail is an important part of the switch point of the railway switch, relying on the pull of the switch rail to guide the train into the direction of the main line or the side line. The point rail can be divided into straight line type and curved type on the plane. Most of the turnouts of No. 12 and below No. 12 in my country's railways use straight-line point rails. Its material is UT71Mn steel. The heat treatment of the tip rail adopts induction heating quenching surface strengthening treatment. A medium frequency induction heating power supply is used to quench and heat treat the small end. Then it moves to the heel end process to improve the quenching quality. The tip rail quenching machine tool is used to set up the quenching guide rail fixture, and a hydraulic cylinder is used to lift it. The bracket performs pre-bending deformation measures on the workpiece. During production, it was found that the distortion of the point rail was large after quenching, and the height of the curved shape reached 150-200mm, which increased the straightening of the workpiece, and even caused some point rails to fail.

According to the analysis, in the induction hardening production of the point rail, the process program and parameter adjustment mainly rely on manual adjustment, which inevitably brings about human factors such as operating errors and delays, and increases the distortion of the workpiece after quenching. After testing, we found that the point rail adopts medium-frequency induction heating power supply for quenching heat treatment and uses computer to control it, so that the distortion of the workpiece is reduced to 35-45mm, which is about 1/4-1/5 of the previous distortion, making the workpiece The amount of bending deformation and straightening is reduced by 80%, and the fit with the base rail is improved, which greatly improves the quality, performance and working life of the workpiece.

During the heat treatment process of the workpiece, affected by many factors, it is possible to produce quenching distortion defects. Therefore, it is necessary to understand the causes of quenching distortion defects and preventive measures. Today, I will briefly tell you about the occurrence of sharp rails. The causes of distortion defects and their preventive measures, I hope everyone can use it in production to produce high-quality point rails.