交错勾齿式小麦精量排种器设计与试验

Design and Experiment of Wheat Precision Seed Metering Device with Staggered Hook-tooth

针对小麦精量播种需求以及现有排种器脉动性高、均匀性差的问题,设计了一种4排交错勾齿式小麦精量排种器,利用勾齿式型孔单粒囊种,并通过勾齿交错布置使下落的种子流形成交错有序的种子面,减少种子间的碰撞重叠,提高种子的有序性。通过对充种过程中小麦种子姿态分析,确定了型孔的关键结构参数和曲线轮廓。运用离散元法EDEM,分析了排种轮转速和充种区域夹角对充种性能的影响规律。仿真结果表明,排种轮转速对充种时处于有利姿态的种子数量有显著影响,充种区夹角的增大有利于提高充种率,但充种区夹角过大会造成成功充入种子掉落出型孔,降低充种性能。在此基础上,以排种合格率、单粒率、空穴率为指标进行了正交旋转组合试验,获得了最优工作参数组合。在排种轮转速、充种区高度以及毛刷/排种轮转速比分别为18 r/min、73 mm、2.5条件下,与现有凸齿式小麦排种器进行对比试验,交错勾齿式小麦排种器的排量变异系数比凸齿式排种器降低0.66个百分点,落种过程中排出的种子交错有序下落,具有更好的排种均匀性。

Aiming at the demand for precision seeding of wheat and the uniformity seed spacing,a precision seed metering device with staggered hook-tooth was designed.The hook tooth were used to grab seeds orderly,and the staggered arrangement of the teeth allows the falling seeds to form a staggered and ordered surface,reducing collision and overlap between seeds.The key structural parameters and curve profile of the hole were determined by analyzing the seed postures during seed-filling process.The effects of the rotational speed of the seeding wheel and the angle of the seed-filling area on the operation performance were analyzed by using discrete element method EDEM.The simulation results showed that the speed of the seeding wheel had a significant effect on the seeds postures.The increase in the angle of the seed-filling area was conducive to improving the seed-filling performance.However,too large an angle of the filling area may cause the successfully filled seeds to fall out of the hole.On this basis of that,laboratory tests were conducted.Qualified rate,single rate,and multiple rate were used as performance indicators.Rotational speed of seeding wheel,height of seed-filling area and speed ratio of brush/seeding wheel were the test factors.The regression equations of the qualified rate,single rate,and multiple rate were obtained.Through the regression equations,it was found that the optimum performance of the seed metering device was achieved.A validation tests were carried out using the optimal parameters at the seeding wheel speed of 18 r/min,the height of seed-filling area of 73 mm,and the speed ratio of brush/seeding wheel of 2.5.The qualification rate was 90.36%,and the single rate was 87.26%,which verified the reliability of the regression model.Comparison tests were carried out by selecting the seed metering device commonly used in wheat planter.A high speed camera was used to capture the process of seed dropping.The metering device designed realized the staggered and orderly seeds falling,which improved the uniformity of seed distribution.The research result can provide theoretical support for the development of wheat precision seeding technology.