Crane rail joint welding preparations and precautions

     Single girder  gantry crane  rail joint welding, should be carefully cleaned groove and the nearby oil, rust and dirt until the exposed metallic luster. Welding basis for such strong principles, matching basic electrode, the grade J857 (National Institute of Standards 4.2 orbital welding deformation control ends of the rails pre-paving height, according to the rail of the species, length and fixed conditions, and environmental factors such as temperature, using preproduction, with the copper plate and steel plate paving the ends of the rails 30 ~ 40mm, has been making good use of such coupling bolts and pressure plate, tighten the nut of the rail fixed to the rail beam, each set at least near the rail joints 4 fixing points.

      When finished welding the bottom rail after the release plate, paving the rail tip portion is reduced to 20mm, and then tighten the gland plate nut. When the welding rail waist-sharing, decreased plate height, waist rail section when finished welding should be removed all the plate, and release plate, this time a small rail joints should be upturned value, rail welding head process, according to resume straight rail, decides whether to tighten the gland plate nuts. In single-girder  hoist gantry crane  All welding process, must always check with straight steel ruler deformation of rail joints, always adjust the height and tighten loose fitting plate to control the deformation of rail joints. In the fixed rail joints before welding, the two ends of the rails gap is left between the wide and narrow, in order to prevail rail base clearance of not less than 12mm, and it is not too wide, the general control within 15 ~ 18mm . After adjusting the fixed rail joints, in addition to ensuring the tip gap size, you must also make the two ends of the rails aligned, may not have contorted and staggered so on.

     In welding single girder  bridge gantry crane  prior to welding process, should be strictly checked and make sure that two rail centerline in a line, in order to prevent orbital welding is completed, there is usually no direct bending phenomenon. Rail with hook bolts, welded joints of its orbit, according to the method described above with reference to specific circumstances, set up a temporary fixture fixed rail for welding.

    Welded rail joint order is bottom-up, after the end of the first rail track waist, rail head, layer by layer carried by road surfacing, the last patch around. Two ends of the range of each track is 40mm, while preheating, preheat and interpass temperature controlled at 300 ℃ ~ 350 ℃. Welding the first layer (primer): Current 120A ~ 130A, to prevent permanent steel plate burn and melt the copper plate, thereby reducing the difficulty of removing the copper plate, shorten the track air time, help maintain the interlayer temperature to prevent quenching; later layers can be used (130 ± 15) A, each finished welding slag must be cleaned before continuing welding;
 
    In each solder wave welding, especially when welding in single girder gantry crane rail base of each solder wave should be used when welding electrode l root end, then use the middle to avoid the broken arc welding, solder wave around two layers The welding should be directed to the contrary; each rail joint welding work should be carried out continuously, so that the rail ends maintained at a high temperature solder (300 ℃ ~ 350 ℃). After welding, stress relieving heat treatment when not cooled prior to beware of rain and other wet; a hot wet cooling copper plate can be removed to facilitate the next reuse.