Study On Cutting Performancesof Roadheader Cutting Head Based On Discrete Element Method

Roadheader is a comprehensive excavating equipment, which occupies an important position in coal mining. As one of the core components of roadheader, cutting head work in complex environment. Uneven distribution of coal rocks lead to great randomness of load of picks. At present, cutting head matched to roadheader produced by China is mostly dependent on import. In the process of using, cutting efficiency of cutting head is lower and consumption of picks is bigger, so it cannot meet the requirements of normal work. Besides, it has some other problems, such as high cost, service difficulty, having no property rights of our own and so on, which lead to a certain limit on the development and profit margins of domestic roadheader. Studying the theory of roadheader cutting coal rocks and analyzing the influence of the design parameters of picks on the load characteristics will help us break the technology monopoly of foreign companies, realize localization and serialization of the whole machine and implement project promotion.This dissertation focuses on the research of the cutting head of EBZ200 boomed longitudinal axis boring machine of a company. The simulation model of the pick cutting process is established by the discrete element method. The influence of parameters on cutting performance of pick is analyzed, which provides theoretical references for the design and installation of picks.Design and evaluation parameters of the cutting head are discussed. Three main properties of coal rocks are analyzed, such as the friction coefficient, strength and firmness coefficient. Cutting functional angles and installation angles of picks on the cutting head and the transformation relationship between them are discussed. Cutting performance evaluation indexes of the cutting head are analyzed, such as the load of single pick, the variation coefficient of load and specific energy consumption.The approximate physical model of coal rocks is fabricated with concrete, and cores are taken from the model. Force-displacement curves of the samples are gotten through uniaxial compression tests. The compression process is divided into two stages, including the elastic stage and the brittle stage. The discrete element model under the condition of uniaxial compression of the sample is established. The result obtained by discrete element model is consistent with the experiment through constantly adjusting the simulation parameters, which provides a basis for correctly selecting physical parameters of coal rocks in the cutting process simulation of pick.The three-dimensional DEM model of the cutting process of roadheader is established. Geometric models of a single pick and coal rocks are established by Pro/E. Mesh generation is carried out on the three-dimensional model by Gambit. The center and radius of the particles are certified by Fluent. Particle deposition and simulation of the cutting process are done by EDEM.The DEM simulation results of the cutting process are studied through curves and charts. The influence of three angles, including cutting angle, rotation angle and halfcone angle, on three cutting performance evaluation indexes, including the load of single pick, the variation coefficient of load and specific energy consumption, is analyzed, which provides a basis for correctly choosing design parameters of picks on the cutting head.