Bridges and gantry cranes should use seamless rails as far as possible, but due to many factors, most of them can only use old rails with a standard length of 12.5m, so there are 16 joints on each Anm line. This has an impact on the operation of the crane. Vibration not only causes low joints on the rails, but also affects the service life and maintenance cycle of the crane components, the comfort of the driver, and the smooth safety of the cargo. Therefore, it is of great practical significance to realize seamless long rail by welding method. At present, aluminum heat welding rail technology is the most widely used, but the cost is large. It is necessary to weld a joint of 2,000 yuan in the engineering section, and the operation is complicated and difficult to promote. I use the most common AC manual arc welding machine to weld the rails of the existing lines. It takes only 120 yuan to weld a joint to achieve better results. It is now summarized for peer reference. (l) The rail is a high-carbon medium-manganese steel for railways (see Table 1). The weldability is poor. Especially, most rails have been quenched on the surface of the rail head when they are shipped from the factory. In addition, the plate thickness is large, and welding cracks are easy to occur. In particular, delayed cracking may also develop in the depth of the base metal (rail) and weld metal under stress. Better welding quality can only be achieved if special requirements are met. (2) The rails and welded joints laid on the line are subjected to dynamic loads during use, and the failure form is fatigue fracture. Therefore, it is necessary to study measures to improve the joint strength according to the form of fatigue load and factors affecting fatigue strength. The weld creates defects such as pores, slag inclusions, incomplete penetration and unfusion. Table 1 Chemical centrifugation of common rails (melting analysis) Steel number chemical composition(%) Mechanical behavior C Si Mn P S Δb/Mpa Δa/% no greater than U71Mn 0.65-0.77 0.15-0.35 1.10-1.50 0.040 883 8 (3) The cross-sectional dimension of the rail changes greatly (see Figure 1 and Table 2). It is of no practical significance to open the U-shaped groove according to the conventional method. Therefore, the groove is not opened, the gap is reserved (track seam), and the back side is added. The welding scheme of the pad. (4) Due to the thermal expansion and contraction of the open rail, one joint should be left for every 100m line, and the rail heads at both ends of the block should be free to expand and contract. The optimum temperature of the welded rail is h-30 °C, and it should be protected from wind, snow and rain during the welding process, otherwise the welding should be stopped. Table 2 Formal dimensions of commonly used heavy rails Track 2 Welding preparation 2.1 Adjusting the rail It is necessary to carry out comprehensive overhaul of the entire line in advance, replace the failure pad, fasteners, gaskets, buffer rubber plates and screws, etc., and find that the rails are damaged, cracked or twisted and should not be replaced, so that the entire line does not look good. Defects such as left and right wrong teeth, unevenness and twists and turns. After the rail is adjusted, it is better to reserve the rail joint 8-10 - if the reserved rail joint is too small, it will not be welded. 2.2 spare weld pad The padding under the joint is used to improve the welding process and the stress state of the weld during operation, thus prolonging the service life of the weld. The backing plate uses Q235-A steel, the thickness of which is determined according to the fixed form of the rail on the reinforced concrete track rail beam. It is better to hang the cushion rubber sheet 2-3 after welding, depending on the situation, take 12-18 one. A piece of ox200Inm. 2.3 Welding equipment and tools Use AC manual arc welding machine (rated welding current up to 300A), oxygen and acetylene equipment, and prepare crowbar, wooden wedge and steel flat ruler. Pointed slag hammer, hand hammer, wire brush, leather tiger, flat grade, live mouth hand, sun umbrella and protective card. 3 welding process 3.1 Select the electrode to use the alkaline low-hydrogen electrode E5016 (D fat), the electrode diameter of 4mm, dry in the 350-4D °C oven for l-2 h before welding, with the use. 3.2 Connector cleaning Insert the protective plate and remove the fastener nut within 3m from both sides of the fishplate and the joint. When the reserved rail joint is less than 8-10, it needs to be cut with oxyacetylene flame, the cut surface is required to be straight, and the unevenness should not exceed 2mm. The rail joint and the two sides of the 20-30 range on both sides need to remove oil, rust and dross. . Next page Nut setter,hex nut setter,magnetic hex nut setter,nut setter factory henan horn tools co.,ltd. , https://www.horn-tool.com
1 Several problems should be paid attention to when welding rails 
Part A B C D E F G H I J 38kg/m 134 114 68 34.6 80.3 19.1 10.3 74.5 59.5 13 43kg/m 140 114 70 31.6 87.6 20.8 11 77.5 62.5 14.5 50kg/m 152 132 70 38.2 92.8 twenty one 10.5 83.5 68.5 15.5