The Computer Simulation Of Shearer Conical Bits Cutting Process

The cutting process of shearer is a complex process, because the strucrure and nature of coal is complex. The coal is not the entity of the same nature in every direction with regular qulity. It is neither the full elastic entity nor the complete plasticity entity, and it is obviously brittle.The paper analyses the physical, mechanics character and damage rule in cutting process, which provides the basic requirement for computer simulation.Through analysis for the cutting theory of shearer,it is realized that the cutting process of shearer involves four periods: the deform period, the crack period, the compaction core forming period, the crack expandition and crumble period. The coal is constantly broken and falls off when the four periods continuously appear. In the cutting process, the loads on pick form in all kinds of complicated and constantly changeable space conditions which accompanies with many random factors. The forces on the pick is simplified to three direction forces: the cutting resistance, the pulling resistance and the side resistance. The main factors affecting the cutting process involves : the shape of pick, the cutting velocity, the cutting thickness, the install angle and the shape of cutting groove. The paper simulates the cutting process of coal with LS-DYNA.The model is directly set up in ANASYS environment for the model is relatively simple in simulation.Before the simulation, it is necessary that material model ,material parameter, restrain qualification and loads should be offered. The choice of the material model is an important problem,it affects the reliability of simulation result.In simulation four schemes are chosen: the different cutting velocities, the different cutting thicknesses, the different cone angles and the different install angles. By simulation the three direction resistances in every cutting conditions are got. Compared with the statistics values of different resistances in the same scheme, some rules are concluded. With Matlab,the frequency spectrum of three direction resistances results are analysed, and energy distribution curves of every load in the frequency field are received. The main frequencies of every load are found out from the curves. The main frequency affects the cutting process greatly, it is attached with the fierce of vibration and work stabilization of the shearer. So inherent frequency of shearer should be far away from these main frequencies in the design of the shearer structure.By dynamic analysis of the stress distribution for the simulation of cutting process, the stress distribution of the coal model is found out, which makes the cutting process realized deeply.