| Abstract:the large rotary drilling rig is important equipment integrated with mechanical, electric and hydraulic technology in foundation construction equipment. Hydraulic Slewing circuit is one of the Hydraulic control circuits for rotary drilling rig, the technological state of the hydraulic slewing system influence directly the working stability, slewing positioning accuracy, efficiency and quality of drilling. At present, several problems exist in different degree when slewing hydraulic system of the domestic large, medium-sized rotary drilling rigs are working, such as stalling, shake of the superstructure because of shutoff pressure, higher system pressure, greater hydraulic impact, greater reverse torque, and so on. In this thesis, the causes about these problems are analyzed; the optimization solutions are put forward from the two aspects of mechanical load characteristics and hydraulic system characteristics, so as to improve the slewing performance of rotary drilling rig. The specific contents are as follows:The effect of slewing load characteristics, especially rotation friction load produced by the superstructure arrangement of rotary drilling rig is analyzed from superstructure kinematics equilibrium. The space coordinates in different position are deduced by D-H coordinate method, and the mathematics model of the slewing moment of inertia is established by using the space coordinate. The General Formula of the MOI is obtained by the algorithm of fitting function in MATLAB software, which is convenient for estimating rotary load, and supplying load sources for relative simulation of hydraulic system.The co-simulation model is established by hydraulic analysis software AMESim and dynamic analysis software ADAMS, and then verified though experiment. Based on the simulation, the reasons of greater pressure fluctuation, higher system pressure and greater hydraulic impact are analyzed more deeply; a series of problems caused by mismatch between valve and valve of slewing hydraulic system for rotary drilling rig at present are put forward, and the improvement schemes are proposed from two aspect of mechanical and hydraulic system, which are verified by simulation model. It is proved that reducing inlet pressure fluctuation of the slewing hydraulic system, eliminating pressure jitter and reducing braking pressure. Meanwhile, these research methods and conclusions provide reference and theoretical basis for the study of energy-recovery about slewing brake and precise positioning, and have important theoretical significance and engineering application value. |
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