基于离散元的马铃薯收获机波浪形筛面参数优化与试验

Parameter Optimization and Test of Potato Harvester Wavy Sieve Based on EDEM

针对分段式马铃薯收获机薯土分离环节伤薯率和破皮率较高的问题,在适应国内北方种植模式和农艺特点的条件下,对分离筛后半段采用波浪形筛面薯土减损分离的结构进行优化。在分析影响碎土分离过程和薯块运动特征的关键因素的基础上,基于构建的离散元土块和薯块模型,明晰了不同波浪形筛面结构参数和运行参数对碎土分离过程和薯块碰撞特征的影响;同时,结合实际工况,验证波浪形筛面薯土分离减损形式的结构合理性和可行性,确定采用振动与波浪形双重分离形式,以期实现较佳的薯土分离和减损效果。试验表明:在2个波峰、2个波谷同等分离行程条件下,波浪形筛面倾角较大时适宜较小的分离筛运行速度,较优的参数组合为波浪形筛面倾角35°、分离筛运行速度1.0 m/s,此时伤薯率和破皮率分别为1.31%和1.44%;波浪形筛面倾角较小时适宜较大的分离筛运行速度,较优的参数组合为波浪形筛面倾角15°、分离筛运行速度2.0 m/s,此时伤薯率和破皮率分别为1.46%和1.67%,相关测试指标能够满足作业需求。

In consideration of the fact that the high rate of damage and bruising of potatoes is the bottleneck of potato harvest mechanization process,the potato’s damage and bruising mechanism,mainly including the impact and collision between potatoes and soil buffer production of potatoes,is not clear.Therefore,it is difficult to combine high efficiency separation with low loss harvesting,resulting in large economic losses,which limits the development of high-performance potato harvester.In the present work,the damage mechanism of potatoes was studied as key point,and the high efficiency,damage reduction and loss prevention in the potato harvesting process were taken as the research objectives.Under the condition of adapting to the planting pattern and agronomic characteristics in the north of China,the separation form of wavy separating sieve was proposed,and the separation mechanism of clods crushing and mechanical characteristics of potatoes on wavy separating sieve were clarified based on the discrete element method(DEM).It was found that the large inclination angle of wavy separating sieve was suitable for the small difference of wavy separating sieve running speed.Simultaneously,combined with the actual working condition of vibration separation,the separation form of damage control device of vibration and wavy separating sieve of potato harvester was optimized.It was demonstrated that the number of crest-trough on the wavy separating sieve in the second half of the separation sieve was two,that was,two wave crest and two wave trough.As a result,under the condition of the same separation distance stroke,when the wave screen surface inclination angle was large,it was suitable for the smaller separation screen operation speed.When the inclination angle on wavy separating sieve was 35°,the separation sieve running speed was 1.0 m/s,the damage and bruising rate of potatoes were 1.31%and 1.44%,respectively.When inclination angle on wavy separating sieve was 15°and the separation sieve running speed was 2.0 m/s,the damage and bruising rate of potatoes were 1.46%and 1.67%,respectively.It was noteworthy that the performance indexes of the damage control device of vibration and wavy separating sieve of potato harvester met the relevant standards.