大型振动筛平稳运行的动力学基础与协调控制研究

Large vibrating screen (LVS) is the key equipment to improve the scale of domestic clean and high-efficient coal utilization. However, nowadays the LVS confront with the problem of low reliability and short service life caused by unstable operation in practice, and cannot meet the demand of domestic large-scale coal preparation. The reason is that the dynamics mechanism of unstable operation of a LVS is not well defined, and the traditional control with a constant exciting frequency is not well adjustable on the unstable operation. To solve the problems above, this project would take the "load bearing"-"dynamic model"-"control method" as the main line, and conduct the research as follows: Firstly, a mathematic model assessing dynamic influence of particle swarm motion would be established, with which the time-varying property of the dynamic vibration mass and the complex dynamic excitation of the particle swarm could be studied; Secondly, the traditional vibrational model of the screening system with less degree-of-freedom (DOF) would be improved to be a 6-DOF one, in which the couple dynamic characteristic of the particle swarm and screen structure would be demonstrated; Thirdly, aiming at a forced-synchronization-excited LVS, the large-span rigid-flexure coupled transmission dynamic model for the exciting system would be presented, then the dynamics mechanism of the unstable operation induced by the large-capacity screening particle swarm and the excitation system would be demonstrated, thus an coordinated control on the exciting-isolation vibration would be proposed for stable operation of a LVS. This project may be helpful for the high-reliability and high-performance of a LVS.

大型振动筛是提高我国煤炭清洁高效利用水平的关键设备，而实际大型振动筛不平稳运行造成了设备可靠性差、使用寿命短等问题，难以满足我国大规模选煤的需求，究其原因，主要是大处理量筛分过程设备不平稳运行的动力学机理不明确，以及传统恒定激振频率控制方式对不平稳状态的调节能力不强。为解决这些问题，本项目将以大型振动筛“承载作用→力学模型→控制方法”为主线，开展以下研究：建立筛分过程粒群动态作用数学模型，探索不同筛分工艺下动态参振质量时变特性和粒群复杂动态激励特性；创新筛分系统平面低自由度振动模型，提出大型振动筛6-DOF动力学模型，研究粒群-筛体耦合系统动力学特性；以单电机驱动的强制同步激振大型振动筛为对象，建立激振系统大跨度刚-柔耦合传动动力学模型，揭示粒群与激振系统诱发大型振动筛不平稳运行的机理，提出大型振动筛平稳运行的激振-隔振系统协调控制方法。项目成果将有助于大型振动筛的高可靠性设计及高效运行。

大型振动筛是选煤生产中的关键装备，可用于煤炭清洁高效利用以解决我国大气污染问题、节约煤炭资源。在激振器和大处理量筛分粒群的联合作用下，传统恒定激振频率控制方式对不平稳状态的调节能力不强大型振动筛动力学特性极为复杂，频繁出现不平稳运行诱发的结构破坏和料群跑偏等故障，可靠性差、使用寿命短，难以满足大规模选煤的生产要求。因此，本项目提出了大型振动筛不平稳运行的动力学机理与协调控制研究，主要研究以下四个方面的内容：.第一，用DEM研究物料对筛面的冲击力，通过正交试验分析粒群对筛面的冲击特性及各振动参数对冲击力的影响规律；此外，运用DEM和FEM的数据耦合(DEM-FEM)研究筛面在冲击力作用下的应力和变形，并对支撑横梁的布置方式进行优化，为振动筛设计及振动参数选择提供了参考借鉴。.第二，以双侧激励大型振动筛为研究对象，应用拉格朗日方程建立其三自由度振动微分方程，结合隔振系统金属螺旋弹簧的横向刚度确定的两种直接方法(即单位力法和能量法)，和两种间接方法(即经验法和本项目提出的弹性压杆模型法)，通过数值仿真及实验验证，实现DELVS精确建模。.第三，建立附加气室空气弹簧的力学模型，得到其隔振参数表达式，建立基于附加气室空气弹簧隔振的振动筛动力学模型，求解出振动筛的动力学特性和工艺参数表达式，搭建附加气室空气弹簧隔振系统，通过实验验证模型的准确性，分析附加气室空气弹簧隔振参数对振动筛动力学特性和工艺参数的影响规律。.第四，提出了振动筛平稳运行动力学模型，引入电机系统数学模型，采用Simulink对搭建方程理论求解，对振动筛启动阶段电机实际转速输入与恒定转速输入振动筛的位移特性进行了比较验证；同时对弹性联轴器径向刚度进行了调整，弹性联轴器径向刚度越大，筛体倾摆越明显。最后提出了平稳运行的协调控制方法。