玉米籽粒收获机可变间隙式过桥设计与试验

Design and Experiment of Variable Gap Conveying Device for Corn Kernel Harvester

摘要:

针对目前玉米籽粒收获机在搭配13行及以上玉米割台以16kg/s的喂入量进行收获作业时，过桥输送能力不足，且在输送过程中喂入量波动较大时易出现堵塞的情况，设计了一种可变间隙式过桥，阐述了可变间隙式过桥的工作原理，并对浮动机构和链耙输送机构等关键部件进行了参数设计和运动分析。利用多体动力学软件RecurDyn建立了可变间隙式过桥虚拟样机模型，运用三维扫描技术获得果穗的物理模型从而在离散元软件EDEM中建立了果穗离散元模型，通过EDEM-RecurDyn耦合仿真的方法获得了果穗在可变间隙式过桥中的运动轨迹以及各个输送阶段的速度和受力变化情况，明确了果穗的输送规律，确定了影响输送效果的主要影响因素。以螺旋输送器转速、输送链轮转速和输送间隙为试验因素，以果穗输送率和损伤率为评价指标，进行三因素三水平仿真试验，并利用仿真试验获得的最佳工作参数进行田间试验，田间试验结果表明，当喂入量为16kg/s、螺旋输送器转速为160r/min、输送链轮转速为460r/min、输送间隙为60mm、脱粒滚筒转速为400r/min、凹板间隙为30mm、风机转速为1200r/min、振动频率为5Hz、上筛筛孔开度为18mm时，可变间隙式过桥的输送率为98.98%，整机籽粒破碎率为1.37%，籽粒含杂率为0.85%，总损失率为1.09%,田间验证试验与仿真试验结果基本一致，满足过桥的工作要求。

Abstract:

In response to the insufficient conveying capacity of intermediate conveying devices in current corn grain harvesters when paired with 13 rows or more of corn headers operating at feeding rate of 16kg/s, as well as the tendency for clogging during fluctuations in feeding volume, a variable gap conveying device was designed. The working principle of the device was outlined and parameter design and motion analysis for key components such as the floating mechanism and chain-type conveyor mechanism were conducted. A virtual prototype model of the variable gap conveying device was established by using the multi-body dynamics software RecurDyn. The physical models of corn ears were obtained through 3D scanning technology, and a discrete element model (DEM) of corn ears was subsequently created in the discrete element software EDEM. By utilizing EDEM-RecurDyn coupling simulation, the trajectory of corn ears within the variable gap conveying device, as well as their velocity and force changes during various conveying stages were analyzed, which clarified the conveying laws of corn ears and identified the primary factors influencing conveying performance. A three-factor, three-level simulation experiment was conducted, with spiral conveyor speed, conveyor sprocket speed, and conveying gap as the experimental factors, and corn ear conveying rate and damage rate as the evaluation indicators. The optimal operating parameters obtained from the simulation experiments were then used to conduct field trials. The field test results indicated that when the feeding rate was 16kg/s, spiral conveyor speed was 160r/min, conveyor sprocket speed was 460r/min, conveying gap was 60mm, threshing drum speed was 400r/min, concave clearance was 30mm, fan speed was 1200r/min, vibration frequency was 5Hz, and upper sieve opening was 18mm, the variable gap conveying device achieved a conveying rate of 98.98%, with grain breakage rate of 1.37%, impurity content of 0.85%, and total loss rate of 1.09%. The field validation tests were in good agreement with the simulation results, fulfilling the operational requirements of the conveying device.