Research On Stability Of Telescopic Boom For Crane Equipped With Super-lift System

With the rapid development of the construction engineering, all-terrain crane is widely used. In order to improve the lifting capacity of cranes, the quality of the telescopic boom is more and more larger and the length is becoming longer and longer, but the problems of the stiffness and stability are more and more prominent. The super-lift system of all-terrain crane is a tow system to improve the deformation and the stress state of the telescopic boom. It can greatly reduce the deflection and enhance the stability of the telescopic boom. Currently, the stability check of telescopic boom is mostly reference the design rules for cranes. But after the super-lift system being installed, the force of the telescopic boom system changes, however there is still no method to calculate the stability of telescopic boom system with super-lift system.In response to the above problems, this paper deeply analyzes the structural characteristics of the telescopic boom system with super-lift system, to realize the stability calculation of the telescopic boom, from the static equation. Taking the500t all-terrain crane for example to study the overall stability of crane telescopic boom, the crippling load which the telescopic boom equipped with the super-lift system or not and the effect of super-lift system parameters on the stability of the telescopic boom were found out. And then, the analytical results were verified with finite element method. The primary work and study content of this paper are as follows:(1) The simplified approach of the mechanical model of telescopic boom system with super-lift system was studied and then the mechanical models were built. Based on the mechanical model, stability analysis and calculation is carried out with the static method, deriving the length of the coefficient which determined by the super-lift hauling cable, and then giving the crippling load expression.(2) Taking the500t all terrain cranes for example, the crippling loads that the telescopic boom can afford under different conditions were calculated. Then the finite element models of the telescopic boom system with super-lift system are simplified and crippling loads of the telescopic boom were solved by the finite element analysis software AN SYS to validate the accuracy of the results.(3) Curves of crippling load of the telescopic boom are drawn by changing super-lift system parameters (including the length of the super-lift pole, the installation angle between the super-lift pole and the telescopic boom in luffing plane, the distance between the installation location of the super-lift pole and the hinge points of boom bottom) in the telescopic booms with the same arm length but different range working conditions. Based on the curves, the optimal values of the parameters or change rules can be found. Comparing the analytic value with the practical value, the reference for practical engineering application was provided.The study shows that the critical force expression derived in this paper has enough calculation accuracy and can be applied to engineering design; the crippling force of telescopic boom with super-lift system is more increased obviously than that without at the same working conditions; the calculation optimal value of the super-lift system parameters are not much different from actual values. The results account for the effect of super-lift system on the stability of the telescopic boom theoretically and provide a theoretical basis for the designed value of the super-lift system parameters.