油菜高速机械离心式集排器设计与试验

Design and Experiment of High-speed Mechanical Centrifugal Centralized Seed Metering Device for Rapeseed

针对传统油菜机械离心式集排器高速作业时供种及投种能力不足,导致排种量与作业速度不匹配、排种性能不稳定等问题,设计了一种被动式供种、“圆孔+渐变孔柱”组合式型孔投种的油菜高速机械离心式集排器。构建了供种、投种过程中的力学模型,分析确定了影响排种性能的关键结构参数;利用EDEM离散元仿真开展了供种调节高度对供种速率调节量影响的试验,结果表明当供种调节高度为3~8 mm时,供种速率在64.95~357.54 g/min范围内可调;采用两因素三水平正交试验分析了限种套筒下摆高度及倾角对初始种量、临界转速及环状种层最大高度的影响。通过台架试验确定了较优限种套筒结构参数,结合高速摄影对比了5种型孔结构下动锥体转速与排种量关系,确定最优型孔结构为“圆孔+渐变孔柱”组合式型孔。较优参数组合集排器排种性能验证试验结果表明:当转速为115~205 r/min时,排种速率为60.96~355.76 g/min,油菜各行排量一致性变异系数均低于5.2%,总排量稳定性变异系数均低于1.3%,破损率低于0.5%,满足作业速度6~12 km/h时的排种量要求。田间试验结果表明,当机组作业速度为7.89、11.98 km/h时,油菜各行植株均匀性变异系数低于11%,种植密度为43~58株/m^(2),满足油菜精量播种要求。

Considering the practical problems that the inadequate seed supply and discharge capacity at high speed operations in the existing mechanical centrifugal metering device for rapeseed which led to mismatch between the amount of seed row and the operation speed,and poor seed row performance,a type of metering device with passive seed filling and"round hole+gradient hole column"combined type holes for seed discharge was designed.The mechanical model of seed supply and discharge process was constructed and the key structural parameters affecting seed discharge performance were analyzed and determined.The experiment on the influence of the seed supply adjustable height on the adjustment range of the seed supply rate was simulated by using EDEM discrete element simulation software,which revealed the seed supply rate was adjustable in the range of 64.95~357.54 g/min when the seed supply adjustable height was in the range of 3~8 mm.The influence of the hem height and inclination angle of the seed limiting sleeve on the initial seed quantity,critical speed and the maximum height of the annular seed layer was analyzed by using two factors and three levels orthogonal test.The optimum structural parameters of seed limiting sleeve were determined by bench test.Combined with high-speed photography,the relationship between the rotating speed of the moving cone and the seed metering amount under five kinds of hole structures was compared,and the optimal hole structure was determined as"round hole+gradient hole column"combined type holes.The bench verification test results of the metering performance of the metering device with better parameter combination at different rotating speeds showed that when the speed of the metering device was 115~205 r/min,the seeding amount rate was 60.96~355.76g/min,the apiece row consistency variation coefficient was less than 5.2%,the single row stability variation coefficient was less than 1.3%,and the damage rate was less than 0.5%,which can meet the working speed of 6~12 km/h.The field experiment showed that when the planting speed was 7.89 km/h and 11.98 km/h,the apiece row plant distribution consistency of rapeseed was less than 11%,and the planting density was 43~58 plants/m^(2),which could meet the seeding performance requirements of rapeseed.