The Pressure Of The Pile Driver Hoisting The Process Dynamics

The hydraulic static pile pressing-in driver is one kind of new type machines assembled the main pile pressing-in driver and the hydraulic crane. The crane arm of hydraulic static pile pressing-in driver can be damaged even broken because of overloading. This phenomenon becomes more serious when the crane is started or stopped abruptly. Some simple apparatus had been designed based on static mechanics to prevent the crane from over loading by the predecessors. But they were of no avail when the crane is overloaded because of dynamic stress. The paper aims at this problem, analyzes the causation of over loading, and researches on the dynamic characteristic of hoisting system during working process. Furthermore, some measures to improve stability are brought forward.Firstly, the relationship between the pressure of cylinder and the angle of the crane boom with different dynamic stress is calculated, and the research about the dynamic tension of hoisting wire rope is necessary. Then the mathematics model of hoisting wire rope is built up and analyzed, thereby the influences of actuator acceleration on wire rope's dynamic tension and dynamic load coefficient are gained. The research about dynamic load coefficient can offer some desirable basis of the calculation on carrying capacity and structure design for the crane.Secondly, the dynamics model of hoisting machine is set up, then the dynamic characteristic of the winch in different working conditions is simulated by using of Simulink tool of Matlab software. Furthermore, the model of crane boom and cylinder system is built using the software AMESim, and its hydraulic system and mechanism is combined well, then the dynamic characters of its main parameters are simulated.Thirdly, in order to improve the stability of the crane, the stiffness of mechanism and some important parameters of the hydraulic system were researched. The results show that, choosing the proper parameters and improving the assembling quality can reduce the vibration effectively. In order to resolve the problem that the operating mode affects dynamic load greatly, used the throttle valve to improve the hydraulic system. And the operating mode that cosine function as input signals of the electro-hydraulic proportional reversed valve is researched. Using these control methods can decrease the impact of the hydraulic system when the position of the valve core changed frequently.Lastly, the pressure of hoist cylinder is tested in different working conditions. The experiments on the ZYB680 type hydraulic static pile pressing-in driver made in Hunan ChangHe Machinery Co., Ltd can prove the validity and credibility of the dynamics analysis about the hoisting machine.