Repair measures for main beam of the hottest rake

2022-07-24
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Repair measures for main beam of rake crane (2)

2.1 construction steps

(1) type II beam shall be made in advance according to the required mid span camber value and the camber curve determined according to the value

(2) remove the electrical control cabinet, trolley conductive frame, trolley limit, buffer, lubrication device, etc. on the main beam. Park the crane in the area reserved for construction

(3) move the trolley to one end of the main beam, weld the construction support, jack up the trolley with a jack and support it firmly

(4) remove the trolley track; Clean the paint and dirt on the upper cover plate of the main beam (for the convenience of later welding construction)

(5) in the middle of the main beam, the main beam is supported by a thousand jacks placed above the steel column, and the height of the jacks is properly adjusted to avoid the increase of residual internal stress in the repair process due to the self weight of the main beam

(6) repair the T-shaped weld crack of the main beam; The new type II beam shall be installed and welded on the original main beam

2.2 features of scheme I

(1) the total height of the main beam is increased by adding type II beam on the upper part of the main beam, the stiffness of the main beam is improved, and the normal stress of the original T-shaped weld of the main beam is reduced by 50.34%

(2) add type II beam on the upper part of the main beam, and all welds are welded on the plane, avoiding overhead welding, so it is easier to ensure the quality of welds; And the construction is convenient, which can greatly shorten the construction time and reduce the construction cost

(3) the n-shaped beam is prefabricated in advance, so it is easy to ensure the upper camber value and camber curve required by the midspan

(4) the use of rolled profile T-shaped steel cancels the T-shaped weld of the general main beam structure at this position, which can greatly reduce the impact of welding stress on the main beam and avoid weld cracking due to weld defects. The development of 3dprts provides a practical scheme to solve the environmental protection problems caused by the rapid consumption of 3D printing materials. 600t

(5) since the scheme does not correct the main beam, the side bending and wave deformation of the main beam cannot be corrected and improved. The quality of domestic T-section steel is average, and the cost is high if imported

3 repair scheme II

as shown in Figure 2, this scheme first repairs the T-shaped weld of the main beam, then flame corrects the downward deflection of the main beam to restore its upper camber value, and finally adds II beam to the lower part of the main beam to reinforce the main beam

3.1 construction steps

(1) move the trolley to one end of the main beam; Measure the down deflection, side bending and diagonal of the main beam

(2) in the middle of the main beam, the main beam is supported by a thousand foot top placed above the steel column

under the action of self weight, the main beam will produce a certain amount of downward deflection, including the tensile stress at the lower part of the neutral layer and the compressive stress at the upper part of the neutral layer. When flame correction is carried out, the tensile stress at the lower part of the main beam will reduce the correction efficiency. By setting support at the lower part of the main beam, the lower part of the neutral layer of the beam is subject to compressive stress, so as to achieve better flame correction effect

(3) repair the T-shaped weld crack of the main beam

(4) flame correction restores the camber value of the main beam. According to the detection results of the side bending and wave deformation of the main beam, the side bending and wave deformation of the main beam shall be corrected at the same time when the flame hot spot is arranged for flame correction

(5) clean the paint and dirt on the lower cover plate of the main beam

(6) add type II beam at the lower part of the main beam to reinforce the main beam

3.2 features of scheme II

(1) during flame correction of the main beam, according to the measured side bending and wave bending of the main beam, the heating area of the flame can be reasonably arranged, and the main beam can be comprehensively corrected to reduce the side bending and wave deformation while restoring the upper arch value of the main beam

(2) the residual stress in the main beam is increased due to flame correction, and its distribution is extremely complex. These internal stresses will gradually tend to homogenize or disappear during the use of the crane, which may cause the

of the main beam to sink again. Adding a type II beam at the lower part of the main beam can keep the camber of the main beam stable after flame correction

(3) this scheme also reduces the normal stress of the original T-shaped weld of the main beam, but the reduction range is smaller than that of scheme I

(4) flame correction is affected by many factors, and the change of its predicted camber value cannot be accurately estimated. Therefore, it is necessary to correct several times and measure repeatedly to achieve better results, so the operation is difficult

(5) the construction of adding type II beam to the lower part of the main beam is difficult, the construction period is long and the cost is high

4 selection of the final scheme and repair effect after comprehensive consideration of the specific actual situation of the unit, the structure of these fixtures has its own advantages and disadvantages, and scheme II is finally selected. In December2003, the company insisted on creating reassuring products for customers. In April 2004, according to this scheme, the main beams of three rake cranes were arched and reinforced. The repair effect was good and fully met the repair technical requirements

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