News
What are the causes of gantry crane girder sinking?
2015-01-07 15:24
What are the causes of gantry crane girder sinking?
Gantry crane in use after a period of time, the girder will sink phenomenon, namely from the original arch down produce permanent deformation. The provisions below the level of permanent deformation of main girder are called deflection. The reason has the following main girder sinking:
1, the use of unreasonable: cranes are designed in the specified conditions of use, is unable to consider for overload and other irrational use. But many use the unit does not pay great attention to the long-term overload, and change the type of work to use, and used for dragging weight, pulling anchor bolt etc..
2 repair, unreasonable: due to the lack of crane metal structure caused by heating structure deformation rules, so also did not take measures to prevent deformation, cutting or welding on the bridge girder, serious deformation, resulting in addition, on the platform on the heating will cause the girder inward side bending, in the end beam heating not only the end of beam deformation, last time, but also affect the deformation of main girder. So, should grasp the deformation rule of metal structure, to avoid heating in the structure, must be welding or gas cutting, as the case may be, and take measures to prevent deformation.
3, crane unreasonable lifting, storage, transportation and installation: Crane for growing up pieces of the structure, the greater elasticity, not reasonable storage, transportation, lifting and installation may cause deformation of the bridge structure. Crane use unit should pay attention to rational use, follow the operating rules and the necessary systems, to prolong the service life of the crane girder is extremely important and prevent sinking.
4, the effect of high temperature: according to the adjustment, the use of thermal processing workshop crane girder than cold processing workshop in the use of crane sinking phenomenon is more common, more serious subsidence degree, the high temperature environment is the most heat caused by radiation. This is because the high temperature environment, to a certain extent, to reduce the yield strength of metal materials, on the other hand, the high temperature environment, will produce temperature stress, this increases the probability that the girder sinking. So, in the use of crane metal structure in the environment of thermal radiation, the lower should increase the heat insulation measures, in order to reduce the effect of high temperature on metal structure.
5, the influence of stress within the structure: pull, pressure effect of each part of crane metal structure exists in different directions. These forces are generated mainly fly, forced assembly structure in the manufacturing process of the deformation caused by the construction of. In addition, because the local welding process of uneven heating, it will cause the weld and near the metal contraction, leading to the girder internal residual stress, and under load, will make the main girder of the great stress caused by permanent deformation. The structure of the residual stress in crane, using continuous process tends to be uniform and even disappear, which caused the sinking of girder.
Gantry crane in use after a period of time, the girder will sink phenomenon, namely from the original arch down produce permanent deformation. The provisions below the level of permanent deformation of main girder are called deflection. The reason has the following main girder sinking:
1, the use of unreasonable: cranes are designed in the specified conditions of use, is unable to consider for overload and other irrational use. But many use the unit does not pay great attention to the long-term overload, and change the type of work to use, and used for dragging weight, pulling anchor bolt etc..
2 repair, unreasonable: due to the lack of crane metal structure caused by heating structure deformation rules, so also did not take measures to prevent deformation, cutting or welding on the bridge girder, serious deformation, resulting in addition, on the platform on the heating will cause the girder inward side bending, in the end beam heating not only the end of beam deformation, last time, but also affect the deformation of main girder. So, should grasp the deformation rule of metal structure, to avoid heating in the structure, must be welding or gas cutting, as the case may be, and take measures to prevent deformation.
3, crane unreasonable lifting, storage, transportation and installation: Crane for growing up pieces of the structure, the greater elasticity, not reasonable storage, transportation, lifting and installation may cause deformation of the bridge structure. Crane use unit should pay attention to rational use, follow the operating rules and the necessary systems, to prolong the service life of the crane girder is extremely important and prevent sinking.
4, the effect of high temperature: according to the adjustment, the use of thermal processing workshop crane girder than cold processing workshop in the use of crane sinking phenomenon is more common, more serious subsidence degree, the high temperature environment is the most heat caused by radiation. This is because the high temperature environment, to a certain extent, to reduce the yield strength of metal materials, on the other hand, the high temperature environment, will produce temperature stress, this increases the probability that the girder sinking. So, in the use of crane metal structure in the environment of thermal radiation, the lower should increase the heat insulation measures, in order to reduce the effect of high temperature on metal structure.
5, the influence of stress within the structure: pull, pressure effect of each part of crane metal structure exists in different directions. These forces are generated mainly fly, forced assembly structure in the manufacturing process of the deformation caused by the construction of. In addition, because the local welding process of uneven heating, it will cause the weld and near the metal contraction, leading to the girder internal residual stress, and under load, will make the main girder of the great stress caused by permanent deformation. The structure of the residual stress in crane, using continuous process tends to be uniform and even disappear, which caused the sinking of girder.
