批次式种子清选机橡胶球清筛装置激振力模拟分析

橡胶球清筛装置清筛性能对批次式种子清选机作业效率与质量具有重要影响，橡胶球对筛面的激振力是决定清筛性能的关键因素。针对橡胶球随机弹性碰撞清筛过程理论解析困难、橡胶球激振力难以精准获取等问题，该研究介绍了橡胶球清筛装置结构与工作原理，分析了橡胶球弹跳产生条件与激振力作用机制；采用Hertz-Mindlin接触模型建立了筛分装置EDEM-MBD耦合仿真模型，并搭建了橡胶球激振力测定装置，单个橡胶球平均激振力、最大激振力模拟值与实测值相对误差分别小于5%、10%，形成了橡胶球激振力模拟方法；采用四因素三水平Box-Behnken试验模拟了不同工况下清筛装置激振力，建立了平均激振力、最大激振力与振幅、振动频率、筛面倾角、球格球数等参数的数学关系；以筛面卡种数量为指标开展了玉米种子清选清筛性能试验，获得了不同振动频率下筛面卡种数量与清筛装置激振力的对应关系。试验结果表明：振动频率为7.2 Hz时筛面无卡种，清筛装置平均激振力8.87 N、最大激振力18.78 N；批次式玉米种子清选作业各工况清筛装置激振力应满足条件：平均激振力≥9 N、最大激振力≥19 N。研究结果可为橡胶球清筛装置清筛机理研究及其结构参数优化提供研究方法与设计参考。

Impulsive force simulation of the rubber ball sieve-cleaning device for batch seed cleaners

Abstract: A batch seed cleaner is a piece of special equipment to meet the specific processing of plot breeding materials. A rubber ball sieve-cleaning device can usually be used as an accessory for a seed cleaner to keep sieve cleaning and avoid sieve-mesh blocking. The sieve-cleaning performance of rubber ball sieve-cleaning devices has an important influence on the operation efficiency and quality of batch seed cleaners. The impulsive force of the rubber ball on the sieve is the key factor to determining the cleaning performance. In this study, the structural and working principles of rubber ball sieve-cleaning devices were introduced to theoretically analyze the random elastic collision screening of rubber balls for the accurate acquisition of impulsive force. An EDEM-MBD coupling model was built for a batch seed cleaner using Hertz-Mindlin in contact mode. A piece of sieve-developed test equipment was utilized to measure the contact parameters, such as the restitution coefficient and friction coefficient for the contact model. A rubber ball impulsive force measurement device was built to obtain the real force of a single ball, according to strain-force measurement. The average and the maximum impulsive force of a single rubber ball were effectively obtained, with the acceptable relative errors between the simulation and measured value, less than 5 % and 10%, respectively. The Box-Behnken experiments with four-factor and three-level were conducted to simulate the impulsive force of sieve-cleaning devices under different working conditions. The mathematical relationships were established between the average or the maximum impulsive force and parameters, such as the amplitude, vibration frequency, screening inclination angle, and ball number. The impulsive force of the rubber ball sieve-cleaning device under different parameters was easily obtained using regression equations. The maize seeds cleaning test under different vibration frequencies was carried out with the index of blockage number, where the relationship was between the blockage number of sieve and impulsive force of the sieve-cleaning device. The test results show that the sieve-cleaning device presented an excellent performance with no blockage on the sieve, with an average impulsive force of 8.87 N and the maximum impulsive force of 18.78 N, when the vibration frequency was 7.2 Hz. An optimal combination was achieved for the screening performance if the average impulsive force not less than 9 N or the maximum impulsive force not less than 19 N. The finding can provide a strong design reference for the screening mechanism and parameter optimization of rubber ball sieve-cleaning devices.