Research On The Influence Of Joints Layout Of All Terrain Crane Super-lift Cable On Telescopic Boom Load

The continuous emergence of all kinds of large-scale hoisitng projects stimulates the rapid enlargement of all terrain crane. As the main bearing structure of all terrain crane, the mechanical properties of boom have a direct impact on the overall performance. By wide use of high-strength steel material, the strength of boom is increased while the problem of stiffness and stability is more prominent. Under working conditions, the deflection of the nearly hundred meters long boom in the head is very large. Since excessive deflection can bring about change of operating amplitude and deterioration of boom force and other adverse consequences, how to further advance the stiffness of the boom system becomes inevitable problem in large tonnage crane design. The lifting performances of some conditions are improved when super-lift cable adjustment frames are used in large tonnage all-terrain crane. However, the mechanism and impact of this kind of structures on the boom remain to be studied.On the basis of previous research on the force of super-lift boom system, telescopic boom installed super-lift cable adjustment frames is taken as the principal object of study in this paper, with two specific structures spacer and eccentric as carriers to carry out the analysis. Component stress of telescopic boom system, as well as bending moment and displacement of the telescopic boom are calculated, and influence regularities of super-lift cable adjustment frames on telescopic boom are explored.According to the design conditions of all terrain crane and the mechanical properties of boom system, establish the mechanical models of tower jib system and telescopic boom system separately. By equivalent beam method based on displacement equal, the equivalent beam for stepped beam model of telescopic boom is obtained, and the equivalent beam method formulae are given. As the super-lift telescopic boom system with spacer or eccentric structure belongs to statically indeterminate problem, force method of structural mechanics is used to solve the mechanical model, and stress calculation formulae of the system components are derived. Finite element method is adopted to validate the model formulae.Taking some500t all-terrain crane for example, component stress of the boom system and bending moment and displacement of telescopic boom are compared before and after installation of spacer or eccentric structure in different conditions. And the results show that the installation of spacer structure can reduce the lateral displacement of boom head while installation of eccentric structure can reduce the bending moment and displacement of boom head in three directions. By means of investigating the influence regularities of parameter variation of spacer and eccentric structures to components performance parameters in the system, the optimal structural parameters of these structures are identified, and a reference for the design is provided. Through analysis of the spacer structure and eccentric structure, the resultes indicate that super-lift cable adjustment frames structures mainly improve the bending moment and displacement of the telescopic boom head.