Welding Process of Overhead Crane Rail Joint

Welding Process of Overhead Crane Rail Joint
In order to make the overhead crane rail transport more stable, rail splints will not be used for the overhead crane rail joint connection, but welded joint connection will be used. The main key to the welded joint is to solve the bending deformation and weld cracking of the overhead crane rail joint. During the welding process of the overhead crane rail joint, the overhead crane rail joint is deformed downwardly, so the overhead crane rail end must be padded to a certain height before welding to ensure that the rail joint can be kept straight after the welding is completed. The height of the rail end pad is determined by factors such as the type of rail, length, fixing method and ambient temperature. The rails are fixed to the crane beam by means of hook bolts, and each joint is provided with four fixed points. After the bottom of the rail is welded, reduce the height to 20mm, and then tighten the hook bolts to continue welding. When the overhead crane rail waist and the bottom part of the rail are welded, remove all steel backing plates, copper pads, and loosen the hook bolts. There should be a slight degree of camber at the rail joint. During the process of applying the rail top, it is determined whether the hook bolts need to be tightened according to the straightness of the rails. In the whole process of welding, it is necessary to check the deformation of the rail joint with a ruler at any time, and adjust the height of the joint and the elastic hook bolt at any time to control the welding deformation of the joint. When we fix the rail joint before welding, the clearance at the bottom of the rail is preferably not less than 10 mm. Before the welding and during the welding process, the coincidence degree of the center line of the two rails is strictly controlled to prevent the entire rail from being bent.
Before welding, oil stains, corrosion, etc. on the surface of the welding area of the rail joint are cleaned with an electric brush until the metallic luster is exposed. In particular, the two vertical end faces are chamfered by a sander and polished at 30°. The shape of the joint end weld is designed to reduce the rigidity of the welded joint, so that the metal at the joint can be relatively freely contracted, and the internal stress is correspondingly reduced. Electric heater is used for preheating and heat preservation. Preheating temperature is 300℃ to 500°C, heating rate is not more than 10 °C / min, holding temperature is 500℃ to 550°C, and maintained at this temperature for 60 min, then slowly cooling, cooling rate is not greater than 8 °C / min, welded joint insulation length of each side is not less than 250mm. Welding is performed by a DC reverse welding method and a multi-layer welding method. The order of welding is to first weld the bottom of the rail, the rear rail and the top of the rail, and finally repair the perimeter. In order to ensure the concentricity of the two rails, the copper plate should be padded at the bottom of the rail. Every time a weld is welded, the weld slag and spatter must be thoroughly cleaned in time to eliminate the defects before continuing welding. The top surface of the rail top and the weld on both sides of the rail are smoothed. When the weld bead is too large, first remove the raised part with a flat shovel, then use a sander to polish the weld to the original surface of the rail, and finally smooth the surface with a trowel or gauze.