【作者】 张勇；

【导师】 李东升；

【作者基本信息】 东北大学 ， 机械电子工程， 2010， 硕士

【摘要】 筛分作业是在冶金、煤炭、化工、医药等许多工业部门重要的生产环节之一,担负着分级、脱水、脱介等重要任务。目前,对筛分过程的研究正在广泛的开展,本文以筛分工艺参数对筛分效率的影响问题,将研究非连续介质力学性质的离散单元法引入到筛分过程的研究中,建立筛分过程研究的离散元模型,用EDEM实现了筛分过程的运动仿真,并对筛上物料的运动状态进行分析。首先,筛分效率是评价筛分效果的一个重要指标,影响筛分效率的因素有很多,本文选取了料层厚度、振幅、振动频率三个主要筛分工艺参数来分析对筛分效率的影响,将离散单元法引入到筛分过程的研究中,根据离散单元法的基本原理及Hertz接触理论,建立了物料颗粒与颗粒、颗粒与筛机边界的接触判断方法。以实验室中的多用途振动实验台与标准分样筛搭建的垂直振动筛作为EDEM仿真实验的研究实例。其次,通过EDEM的仿真实验,得到了筛分过程的筛分效率,以及物料在振动筛面上的运动状态,分析了物料的运动状态对筛分效率的影响。将由EDEM仿真实验中得到的筛分效率与其对应的筛分工艺参数通过Matlab BP神经网络建立并训练了网络模型,并借此对筛分工艺参数进行了优化。最后,设计了实际筛分实验,通过实验的结果计算出了筛分效率,将实际实验的筛分效率与仿真得到的筛分效率进行对比,验证了EDEM仿真中所得的筛分效率的准确性,并且通过实际实验证明了用BP神经网络建立并训练的筛分效率与筛分工艺参数间的网络模型的性能符合要求,进而证明了使用BP网络对筛分工艺参数的优化结果也是正确的。更多还原

【Abstract】 Screening operation is an important production processes in the metallurgy, coal, chemical, pharmaceutical and many other industrial sectors, shoulder grading, dehydration, and other important tasks. At the present time, research on screening operation is developing healthy. This article is the screening process parameters on the impact of screening efficiency of problem. This article introduced "Discrete Element Method(shorted DEM)" used in screening process research, and established discrete element unit models for screening process research. This article achieved the motion simulation of screening process in EDEM, and analysis the state of motion of screen materials.Firstly, the screening efficiency is an important indicator of evaluate the screening results. There are many factors affect the screening efficiency, this article selects the material layer, amplitude, frequency of three screening process parameters to analyze the impact of the screening efficiency. Using basic principle of DEM and Hertz contact theory, this article introduced the judgment methods of material particles contact with each other and particles contact with boundary. Based on an example of vertical vibrating screen which consists of vibrating bench and standard screen, we made dynamic analysis of the vibrating screen and calculated its natural frequency to design the screening process parameters in the simulation of EDEM.Secondly, through the simulation of EDEM, we gained the screening efficiency and the motion state of the materials on the screen surface. Analyze the influence of motion state to the screening efficiency. Using the screening efficiency of simulation and its screening process parameters establish and train a BP network, and use the network optimal the screening process parameters.Finally, design a practical screening experiment, based on the results of the experiment, we calculate the screening efficiency. Through the comparison of experiment and simulation, we can verify the screening efficiency of simulation is correct, and verify the performance of BP network to meet the requirements, and then verify the optimized of the screening process parameters is also correct.更多还原