玉米收获机聚氨酯橡胶筛筛分性能仿真与试验

为降低玉米贯流式风筛加工成本、加工难度以及提高筛面物料的分散程度,采用新型聚氨酯橡胶筛代替金属筛,试验测得筛面上各颗粒相与聚氨酯橡胶间的静摩擦因数、碰撞恢复系数等物理参数,并推导出聚氨酯橡胶的剪切模量。利用EDEM建立筛板上的各颗粒相模型,通过CFD-DEM耦合方式对聚氨酯橡胶筛上不同区域的颗粒相数量进行数值模拟分析。聚氨酯橡胶筛的仿真结果表明,相同时间聚氨酯橡胶筛上颗粒相的分散度大于金属筛上颗粒相的分散度,证明聚氨酯橡胶筛更有利于物料的分散,进而提高筛面的使用效率。当喂入量为5 kg/s,玉米清选装置入口风速为12 m/s时,清选装置清选损失率为1.93%,达到玉米收获机国家标准和行业标准要求,聚氨酯橡胶筛使籽粒清洁率达到95.3%,相对于金属筛提高了16.33个百分点。

Cleaning of Maize Mixture Based on Polyurethane Rubber Sieve

In order to reduce the cost and difficulty of manufacturing, and increase the degree of dispersion of sieve particles on the maize air-and-screen metal sieve, a new polyurethane rubber sieve was used to replace the metal sieve, the density of polyurethane rubber and the physical parameter between particles on the sieve and the polyurethane rubber were obtained through experiment, including coefficient of static friction and coefficient of restitution, the shear modulus of the polyurethane rubber was deduced. EDEM was used to establish models of particles on the sieve. The number of particles on different regions of the polyurethane rubber sieve was analyzed through computational fluid dynamics and discrete element method. The simulation results showed that the dispersion of the particles on the polyurethane rubber sieve was greater than that of the metal sieve at the same range of time, which proved that polyurethane rubber sieve was more conducive to particles dispersion which improved the efficiency of sieve. The tests were performed based on the experimental system to verify whether the urethane rubber sieve was met the operational requirements. The loss rate of maize of cleaning device was 1.93%, when the normal feed quantity of maize mixture was 5kg/s, the inlet wind speed of cleaning device was 12m/s, which met the national standard and the technical specification for quality evaluation of maize harvester. Cleaning rate of maize of polyurethane rubber sieve, which was increased by 16.33 percentage points through the comparison with metal sieve, was up to 95.3%.