Control of Welding Deformation of Crane Rail Square Steel

Control of Welding Deformation of Crane Rail Square Steel
The pre-padded height of the crane rail square steel bar end is determined according to the type of the rail, the length and the fixing condition, and the ambient temperature. The copper pad and the carbon steel plate are used to underlay the crane rail square bar end 30mm to 40mm. With the adapting pieces, like bolts and pressure plates, we can tighten the nuts to fix the crane rail steel square bar to the rail beams, and set at least 4 fixing points near each rail joint. After welding the bottom of the track, loosen the platen, lower the padded portion of the rail end to 20mm, and then tighten the platen nut. After welding the waist portion of the crane rail square steel, gradually reduce the height of the mat. After the rail waist portion is welded, all the shim plates should be removed and the pressure plate should be loosened. At this time, the rail joint should have small upturn value. During the welding process, whether to tighten the platen nut again depends on wether the rail is flat or not. During the entire welding process, the deformation of the rail joint must be checked at any time with a straight steel ruler, and the height of the joint and the tight pressure plate are adjusted at any time to control the deformation of the rail joint. When the rail joint is fixed before welding, the gap between the ends of the two rails is narrower than the upper and lower, which is based on the clearance at the bottom of the rail, not less than 12mm, and should not be too wide, generally controlled within the range of 15mm to 18mm. When the rail joint is fixed, in addition to ensuring the size of the end gap, it is necessary to align the ends of the two rails without any twisting or staggering.
Before welding and during welding, strict inspection should be carried out and the position of the center line of the two rails should be in a line to prevent the bending from being straight when the orbital welding is completed. When the rails fixed by the hook bolts are welded and the rail joints are welded, the above method can be referred to according to the specific conditions, and the temporary clamps are fixed to fix the rails for welding. The order of the welded rail joints is from bottom to top, the first rail bottom rail rear rail, the rail head, the layer by layer, and the last repair. The range of the two track ends is 40mm, and the preheating is carried out at the same time. The preheating and interlayer temperature are controlled at 300 °C to 350 °C. The first layer of welding, current 120A to 130A, to prevent the permanent carbon steel pad burning through and the copper pad melt, thereby reducing the difficulty of removing the copper pad, shortening the track air cooling time, in order to maintain the interlayer temperature and prevent quenching. In the future, (130±15)A can be used for each layer, and the welding slag must be removed before each layer can be welded.