During the transportation operation of the bridge crane, the crane always runs on the track, so the track bears the lifting load transmitted by the wheels, the weight load of the crane itself and the additional load caused by various reasons during the operation. As an important part of the overall lifting system, the quality of the track not only has an important impact on the structural performance of the crane itself, but also has an immeasurable impact on the entire operation process.
The installation of crane rails is generally the responsibility of the user. The supervision and inspection regulations for hoisting machinery only have requirements for the installation of crane rails on joint clearance, fixing methods, physical defects, and gauge deviation, and the rest are not specified. Therefore, for testing and inspection agencies, they can only conduct supervision and testing from the above aspects. The user is responsible for the installation of the rail, and it is impossible to guarantee the quality of the track installation. The reality is often that when a problem is discovered, it is already done, and the result can only be repaired, which lays a hidden danger for the safe operation of the crane in the future.
This article will discuss several problems and links that are easy to appear during the installation process of the crane rail, but are easily overlooked in the inspection process of the crane and have an important impact on the performance of the crane, and take corresponding countermeasures to ensure that the crane job security.
1. Selection of track
The lifting rail generally adopts standard section steel and steel rails. Usually, P-type railway rails are used when the wheel pressure of the crane is small, and QU-type crane special steel rails are used when the wheel pressure is large, and square steel is used as the crane rail, which should only be supported on the steel structure.
1.2 The effect of the track on the crane.
The track selection should fully consider the structure form of the wheel and the wheel pressure load to ensure that the selected track meets the basic structure and strength requirements.
In the selection process, especially in order to reduce costs, used, worn, old rails or old railway rails should not be used as crane cart rails, because no matter the internal metal structure of the rails, or the strength and hardness, and the overall dimensions are far from meeting the requirements of the crane itself on the track.
If there is a deviation in the selection, it may still be used at that time, but as time goes by, the problem will gradually appear, entire accelerating the wear of the wheels or rails, or plastic deformation of the rails, which paralyze the entire system, cause lifting accidents, resulting in loss of personnel or property.
In the selection stage are usually resolved through consultation between the user and the manufacture, and inspection and tasting agencies are rarely involved in this stage. Users should actively consult relevant technical experts or units to obtain accurate information and ensure that they can choose the correct track model.
2.The track installation from
The track installation from should fully consider the track installation and fixing method, and determine the track fixing method that suits you and meets the corresponding standards according to the actual situation of the factory building and construction site.
2.1The installation and fixing methods of the rail generally have the following three methods:
(1)The pressing plate fixing method: Lay the guide rail directly on the concrete support beam, and fix the guide rail with a fishtail plate. The original old-fashioned factory buildings often use this installation method, and the track support beams are poured together with the factory building. With this installation method, the crane runs smoothly with little vibration and noise, and the cross-sectional area of the support beam is large, and some have pedestrian passages, which is very convenient for the inspection and maintenance of the track, and it is easy to find and solve problems.
(2)liftinHook bolt fixing method: This method is mostly used in metal structure workshops currently built. Weld the support block on the pillar of the factory building, lay the I-beam, and fix the guide rail by hook bolts or welding. Since the pillars and support beams are all metal structures, the crane vibrates and noises a lot during operation, and the inspection space is small. The requirements for firm fixing and stability of the pillars are high, but it is convenient for construction and the construction speed is fast.
(3)Sleeper fixing method: This method is mostly used fr gantry cranes on construction sites. After laying stones on the ground, guide rails are laid. Generally, the cross-section size of sleepers is 200-300mm, and the spacing is generally about 600-800mm. This installation and fixing method is more convenient to disassemble and move.
2.2The influence of the installation method on the crane
The track has a large deformation: when the track is laid, there are often some enterprises in the workshop with brick stacks, the track is laid directly on the 2 stacks, the fixed track on the stacks, the crane began to run after the frame. Generally, the span of the two stacks is about 36metes. The deformation of the track can be calculated according to the load on the track and the elastic modulus of the track itself. Through actual calculations, it can be known that the deformation is very large.
If the deformation is outside the range of elastic deformation, that is, plastic deformation occurs, a car collapse accident will occur.
Incorrect selection of installation and fixing methods will generate large operating noise and vibration, especially for new steel structure workshops. Influence, thereby affecting the safe operation and communication of operators.
2.3 Measures Select
Correct installation mode: Learn more about the relevant laws and standards before determining the installation mode, and choose the installation mode that is suitable for your actual situation and meets the standards. Don’t just assume an installation plan.
In order to control the noise, the usual practice is: put a certain thickness of industrial rubber plate under the rail or cushion plate; It has to be true for the joints of the track; Ensure that the clearance of track joint meets the specified requirements; Check and repair track and crane fasteners in time.