How to weld long rails
1. The rail to be welded shall meet the requirements of relevant technical conditions for rail of new railway line.
2. Contact welding shall be adopted for rail welding at base.
3. The operators of welding equipment must receive professional training, be familiar with the quality standard of rail welding head, pass the examination of relevant departments, and obtain the operation certificate.
4. Operators must strictly implement the operation regulations of welding equipment and operate according to the operation parameters determined by formal inspection.
5. Basic welding process of long steel rail:
Rail selection and allocation → rail head alignment → rail end treatment → welding → normalizing → weld rough grinding → weld cooling → rail four-way straightening → weld fine grinding → flaw detection, acceptance → storage.
6. Before welding the long steel rail, the rail distribution schedule shall be prepared according to the design requirements.
7. The rail relative welding with unsymmetrical cross section and basically consistent tolerance shall be selected for rail distribution. The deviation of the head and tail rail length shall not be greater than 6 mm
8. Cut and saw the rail according to the requirements of rail distribution and alignment. After the rail hard bending is straightened, its sagittal shall not be greater than 0.2mm measured with a 1m ruler
9. The dirt within 0.5m of rail end shall be removed, and the end face of rail to be welded and the contact part between rail and electrode shall be polished and derusted. The metal luster is more than 80%.
10. When the ambient temperature is lower than 10 ℃, the heating temperature of the two rail ends before welding shall meet the relevant requirements for rail welding of new railway.
11. Before the rail enters the welding machine, the quality of rust removal shall be checked. If the derusting quality is poor, it should be returned for re derusting,
12. After the rail enters the welding machine, the working face shall be taken as the reference during the alignment. The displacement deviation of rail head working face shall not be greater than 0.2mm, and the misalignment deviation of rail bottom edge shall not be greater than imm
13. The electrode surface of the welding machine must be smooth and smooth, and should be treated in time after burning and replaced if necessary.
14. The electrode shall be cleaned after each welding joint is welded, and no dust and slag shall be left. The electrode and guard plate shall be cleaned once every long rail is welded.
15. After welding, the welding joint shall be identified immediately. The joint identification shall correspond to the rail mark, welding record or report. The mark shall be at the rail waist 3-5M in front of the welding joint, and the identification symbol shall be clear and correct.
16. When the temperature of welding joint is lower than 500 ℃, it can be heated by normalizing. The surface temperature of rail head heating should be controlled at 900 ℃± 20 ℃, and the surface temperature of rail base angle should be controlled at 800 ～ 900 ℃.
17. Straightening after welding shall be carried out after heat treatment of welded joint, which can be straightened under hot or cold state. The hot straightening temperature of welded joint should be lower than 400 ℃, and the camber amount should be reserved; the cold straightening temperature should be lower than 50 ℃, and the im length after straightening should be 0.3-0.5mm. It is not suitable to straighten repeatedly.
18. Before finishing grinding, the temperature of welded joint and its two ends within 1m shall be controlled below 50 ℃.
This article comes from the customization of automatic welding equipmenthttp://www.abbzs.com