Dynamics Research On Travelling Mechanism Of Crawler Mining Excavators

Mining excavators are one of the indispensable important mining outfit equipment in open cast, mainly used for loading and excavation. With the scale continuous expand of domestic and oversea mining, as well as the level of mining technology and equipment technology improve, in order to further enhance labor productivity and economic efficiency of enterprises, reduce the cost, open-air mining excavators toward large scale development is the trend of the times.Driving distance of large mine excavator is short and travelling speed is low, in addition, large impact load is generated in the course of operations, what is more, it's working conditions are poor. These characteristics determine that the travelling mechanism should be able to bear a larger impact load, and has better stability, trafficability and mobility. Crawler is widely used in mining excavator due to meet its requirements.Because of cost and other factors, at present, the load spectrum experiment of the current domestic large scale crawler mining excavator very limited, and the reference data is relatively small. Based on the conditions mentioned above, using of virtual prototype technology for computer simulation research on crawler, to understand the dynamic performance of travelling mechanism relatively easy to achieve.In this paper, research on travelling mechanism of large scale crawler mining excavator by combining the method of theoretical analysis and computer simulation, emphatically analyze the dynamic characteristics of thrust wheels on travelling mechanism. First, based on the theory of classic soil - vehicle system mechanics, establishing the mechanical model of thrust wheel, and theoretical analysis of vertical load acts on thrust wheels. Then the dynamical simulation to travelling mechanism is conducted using such dynamical simulation analysis software of ADAMS, mainly analysis size of load on each thrust wheel and groung pressure distribution under four typical working conditions, as well as the frequency domain feature.According to the load characteristics of thrust wheels, a mechanical model of interaction of thrust wheel crawler and soil was built in Theoretical analysis part, mainly discusse the size of vertical load on each thrust wheel. The unknown variables are involved in the model are entry and exit angel of the thrust wheel, along with the track tension in entry and exit angel. Finally the theoretical value of the vertical static load was worked out by software of MATLAB. Theoretical results show that the distribution characteristic of ground pressure is that the vertical load of thrust wheel from guide wheel to driving wheel in turn increase, the distribution presents the triangle state, and the vertical load size of the rear thrust wheel more than twice of its front thrust wheel.Establishment of the prototype model is the key in the virtual prototype simulation parts. The most critical is the choice of contact force parameters and add contact force, which are the important part to affect the accuracy of simulation results. Contact parameters are determined mainly based on material characteristics of structural components and structural features. In order to more effectively reflect the dynamic characteristics of crawler, the friction of track shoe pin and journal friction of thrust wheel, guide wheel and driving wheel are considered in prototype model.This paper's analysis mainly aims at four typical operation condition, i.e. flat uniform forward, uniform climbing, in-situ uniform steering and unilateral drive steering. The size of vertical load on thrust wheel, distribution characteristic of ground pressure and spectrum characteristics are obtained in each condition by computer simulation. Load curve of four features thrust wheel on each condition are selective analysis in this paper, then giving the load of unilateral or bilateral all thrust wheels and plotting curve, finally take a spectrum analysis of thses load curves. The simulation result has validated that the differences existed in the load size of each thrust wheel and the distribution characteristic of groung pressure under the same and different operation conditions.In this paper, the research contents have certain theory reference value for studying the machine performance, structure optimization and improve of large scale crawler mining excavator.