Common Faults Of Main Girder Of Double Girder Crane

Common faults of Main Girder of Double Girder Crane

1. The welding of the main girder of the double-girder crane and the opening of the truss node exist:
 

The reason may be that the welding quality is poor, there are shortcomings such as missing welding and air holes.
 

Long-term overloading of the crane.

2. Cracks occur on the web and cover of the main board of the double-girder crane:
 

The main reason may be long-term overloading. If the crack is small, it can be smoothed with a grinding wheel. If the crack is large, holes can be drilled on both sides of the crack, and then welded with high-quality welding rods.

3. The web of the main girder of the 25 ton double girder crane has wavy deformation:
 

This situation may be caused by the internal stress caused by improper welding process or the loss of stability of the web caused by overloading the double girder crane.
 

In this case, you can use the flame rectification method, which is to level the deformed place first, and then hit it with a hammer to eliminate internal stress. It is also forbidden to use a double-girder crane for overload.
 

The main beam is bent inward and sideways.
 

This deformation is often partially bent with traces of collision, and the degree of inward bending of the upper and lower cover plates is different, and the lower cover plate is probably more serious.
 

Correction of this kind of side bending can generally be carried out simultaneously with correction of the main girder’s downdeflection, that is, according to the requirements for the correction of downdeflection deformation, the heating zone should be properly arranged at or near the most prominent side bend.
 

Because the main beam and the end beam are not perpendicular, a main beam bends inward and sideways. This is actually the angular deformation between the main girder and the end girder, which usually makes the diagonal line of the bridge out of tolerance, and can be heated outside the end of the main girder during correction. Because the rigidity of the main beam is far worse than that of the end beam, the rectification method and the angular deformation of the end beam can cause a large amount of bending deformation of the main beam.
 

The main girder is bent outwards.
 

The outward side bending of the main beam is mostly caused by improper storage and storage or collision. If a small amount of side bending does not cause the trolley to get stuck on the track, it does not need to be repaired, because it will gradually move inward after use. If the amount of outer bending is too large, select a strip-shaped heating zone on the side beam of the walkway where the outer bending is the largest.
 

Before the fire, the walking platform at the convex part should be cut horizontally, and the main beam should be straightened with pullers or manual hoists and flame straightening, and then the cut part should be welded. At this time, the pull plates used should be welded to the upper and lower cover plates respectively.
 

Most of the main girders are bent inward and sideways, which should be corrected according to the cause of the deformation and the shape of the deformation. The side bending can be corrected by correcting the deformation of the end beam (bending or deflection of the end beam), heating the end of the main girder, correcting the deflection of the main girder, correcting the wave shape of the web of the main girder, and cutting the walking platform.