基于刚柔耦合的水稻脱粒滚筒仿真分析与试验

Simulation analysis and experiment of rice threshing drum based on rigid flexible coupling

为降低4LZ-4.0型联合收割机机收作业中籽粒破碎率,提高清洁度,依托纵轴流差速分段式脱粒滚筒,设计了杆齿、弓齿和刀齿3种形状的脱粒元件,通过改变脱粒元件表面与籽粒碰撞时的接触状态,刚柔耦合成6种类型脱粒滚筒;基于冲量-动量定理对籽粒碰撞过程进行分析,通过仿真试验得到刚性杆齿和刚柔耦合杆齿与水稻籽粒谷物接触时籽粒所受法向力均值分别为28.4 N和22.3 N,籽粒所受切向力均值分别为14.43 N和8.74N。以前滚筒齿形、前滚筒转速和前后滚筒转速差为影响因素,以水稻籽粒破碎率和未脱净率为评价指标进行3因素3水平正交试验。结果表明:前后滚筒转速差对破碎率的影响最大,前滚筒齿形对未脱净率的影响最大;试验得到的最优组合为前滚筒齿形为弓齿、前滚筒转速为600 r/min、前后滚筒转速差为100 r/min;与刚性脱粒元件相比,带有聚氨酯橡胶套的刚柔耦合脱粒元件可有效降低水稻籽粒破碎率,平均可降低18.5%。

In order to reduce the grain crushing rate and improve the cleanliness in the process of rice harvesting,three types of threshing elements,namely rod teeth,bow teeth,and cutter teeth,were designed based on the longitudinal axial flow differential segmented threshing drum.By changing the contact state between the surface of the threshing element and the grain during collision,six types of threshing rollers were obtained by rigid flexible coupling.Based on the impulse momentum theorem,the collision process between grains was analyzed.Through simulation experiments,it was found that the average normal force on grains was 28.4 N and 22.3 N,and the average tangential force on grains was 14.43 N and 8.74 N,respectively,when the rigid rod teeth and the rigid flexible coupling rod teeth came into contact with rice grains.Three-factor and three-level orthogonal test was carried out by taking the tooth shape of front roller,the rotation speed of the front roller and the rotation speed difference between the front and rear rollers as influencing factors,and the broken rate and undrained rate of rice as evaluation indexes.The test results show that the rotation speed difference between the front and rear rollers and the tooth shape of the front roller have the greatest influence on the broken rate and the un-threshing rate,respectively.The optimal combination obtained from the experiment is that the tooth shape of the front roller is bow tooth,the rotation speed of the front roller is 600 r/min,and the rotation speed difference between the front and rear rollers is 100 r/min.Compared with rigid threshing components,the average grain broken rate of rice can be reduced by 18.5%.