Key points for daily maintenance of fasteners rela

Key points for daily maintenance of fasteners related to tower crane

when repairing parts of the working mechanism of tower crane, bolts, screws, nuts, spring washers, cotter pins, keys and other fasteners must be checked at the same time to determine whether they can be used or replaced

bolts for tower crane can be divided into shear bolts and tensile bolts. The connecting bolts of metal structures are mostly shear bolts. The connecting bolts of some tower cranes, such as qt80, qt80 eight and other tower body sections, are tensile bolts. The function of shear bolt is to ensure that the bolt position remains unchanged and will not produce axial movement. It is generally made of 35 steel, while tensile bolts are mostly made of 40Cr steel

common defects of bolts are: bolt breaking and wear; The freight volume of threaded Daqin line has climbed by nearly 30% year-on-year, which is squashed and crushed, the screw head is damaged, the rod body is bent, and the nut corners are squashed

the thread should have correct tooth shape, no defect, clean surface and no rough burr. The nut should fit closely on the screw and be easy to tighten without looseness

if there is a large gap in the bolt connection, it indicates that the connection has been loosened, weakened, or damaged, and must be replaced immediately

the crushed thread can be repaired with die. The repaired thread shall not have burrs, and the outer diameter shall not be 0.2mm larger than the standard. The crushed part of the bolt end can be cut off

if the thread part of the tension bolt is damaged or the nut corner is severely squashed, it must be scrapped. When the deflection of the shear bolt exceeds the full length of the bolt by 0.2, it shall be scrapped. Nuts with broken threads, weakened threads and flattened edges and corners shall also be scrapped

when disassembling and inspecting the spring washer and cotter pin, the following methods can be used for conditioning: turn off the power switch of the machine and replace it all. Ordinary iron wire shall not be used. Damaged, deformed and crushed keys must be replaced. Do not use keys with excessive clearance or add pads in the clearance

these data or sealed in their respective files

the connecting bolts at the flange of channel steel should adopt the offset pad with a slope of 1:10, and the bolts at the upper and lower flanges of I-steel should all use the offset pad with a slope of 1:6