| With the rapid development of the global economy,modern engineering construction is increasingly developing towards high altitude in recent years.It is relatively demanding for the construction space.On account of construction work in a narrow space at heights,the full hydraulic boom tower crane is becoming the first choice now.It is used widespread because of its superior lifting height,large working amplitude,strong carrying capacity and so on.But the full hydraulic boom tower crane is self-heavy and amplitude with load,frequent operating condition changes will bring oscillations and shocks to the luffing mechanism.This oscillation comes from the dynamic effect caused by the elastic deformation of the flexible elements of the luffing mechanism.For hydraulically driven luffing mechanisms,the mechanism of this dynamic effect is more complicated.it will affect the stability of the work of the luffing mechanism.It will also cause the pressure shock of the hydraulic system,which will greatly threaten the service life of the hydraulic components.The paper sets a full hydraulic boom tower crane with a maximum lifting moment of2400t·m as a study focus.When the luffing mechanism is under load,and the inertia load is increased.The aim of this paper is to solve the pressure impact and the boom swing problem caused by the luffing mechanism.The mechanical-hydraulic integration simulation method is used to analyze the dynamic characteristics of the luffing mechanism.Compared with the traditional method of dividing the luffing mechanism into two subsystems,computer system and hydraulic systems,it pays more attention to the mechanical-hydraulic coupling relationship.The effect of dynamic characteristics,the simulation results are more in line with the actual.According to the simulation experiments,the influence of mechanical and hydraulic coupling on swing and pressure impact are studied.After improving the hydraulic system of the luffing mechanism,the mechanical and the hydraulic are more compatible.First,use AMESim software to build a hydraulic-mechanical integrated simulation model of the full-hydraulic boom tower crane luffing mechanism and set the simulation conditions.Under no-load conditions,the correctness of the modeling is verified while the amplitude of the luffing mechanism is changed.Analyze the dynamic process of the luffing process at the lifting condition of 13 t at the maximum working width of 80 m.It is clear that the inertial load generated during the working condition conversion is the cause of thepressure shock and the boom swing of the luffing mechanism.Subsequently,the influencing factors of the dynamic characteristics of the luffing mechanism are analyzed,that is,the time when the luffing wire rope,the directional valve is fully opened,and the balance valve.Optimize these influencing factors,simulation results show When the boom is lowered,the differential pressure fluctuation of the motor drops by 34.1%,and the swing of the boom has been basically eliminated.However,shocks and swings still exist when the amplitude rises.Combining related literature,by adding accumulators and adjusting related parameters to the hydraulic system of the luffing mechanism to improve the hydraulic drive circuit of the luffing mechanism,the factors affecting the dynamic characteristics of the luffing mechanism and the mechanical and hydraulic coupling to the system pressure shock and dynamic effects of arm swing.The simulation results show when the amplitude rises,the peak pressure shock of the system decreases by 16.84% and the maximum amplitude of the boom decreases by38.12%.When the boom is lowered,the differential pressure fluctuation of the motor drops by 34.1%,and the swing of the boom has been basically eliminated.This paper provides a theoretical basis for the research on the hydraulic-integrated joint simulation of a full hydraulic boom tower crane,which has reference significance for the research of other high-power mechanical-hydraulic integrated systems. |
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