链喂入摘辊与柔性杆联合拨断式菠萝采摘装置研究

Design and Experiment of Chain Feeding Combined with Roller and Flexible Rod Breaking Pineapple Picking Mechanism

摘要:

针对菠萝采摘机械化程度不高的问题，设计了一种链喂入摘辊与柔性杆联合拨断式菠萝采摘装置。分析了影响该装置采摘效率的因素：摘辊长度、安装高度、间隙、半径和角速度。通过力学分析推断出该采摘装置工作时菠萝果实与茎秆分离模式为折断。为提高折断成功率，在摘辊上方安装一排旋转的柔性杆，并对柔性杆半径和角速度进行计算。该装置最佳参数组合为：摘辊高度200 mm、机具前进速度0.6 m/s、摘辊半径和角速度分别为35 mm和12 rad/s、柔性杆半径和角速度分别为20 mm和10 rad/s，在该参数组合下，试制样机并进行了田间试验，结果为菠萝采摘率为82%，损伤率为34.14%，综合评价指标为77.16%。

Abstract:

In order to promote the mechanization level of pineapple harvesting and improve its efficiency, a pineapple picking mechanism was designed. The mechanism fed fruit by using a chain feeding, removed fruit by using a pair of rollers and a rotational cylinder which had several flexible rods mounted on the cylindrical surface. Firstly, guiding mechanism was a pair of chain mechanisms with chain claws. Several key parameters that affected the picking efficiency of this mechanism, including the radius, length, mounting height, rotational speed of that pair of horizontal rollers, rational gap value between that pair of rollers were analyzed, and their computing methods were put forward. The radius calculation method of those flexible rods which were mounted on the rotational cylinder was purposed by using a pseudo-rigid body theory, and a suitable range of the rotational speed of those flexibles rod was determined. An experimental machine was designed and manufactured to test feasibility of the harvesting mechanism. That experimental machine consisted of a tractor, a diesel engine, and a harvesting mechanism. The field experiment results showed that the optimal parameter combination for this mechanism was that the forward speed was 0.6 m/s, the radius, installation height and rotational speed of the horizontal roller was 35 mm, 200 mm and 12 rad/s, respectively, and the radius and rotational speed of the flexible rod was 20 mm and 10 rad/s, respectively. Under the optimal parameter combination, the harvesting rate, damage rate and comprehensive evaluation index was 82%, 34.14%, and 77.16%, respectively. The average harvesting time request for each pineapple was less than 1 s. In addition, those pineapple plants after harvesting could maintain good growing condition. The research results indicated that this harvesting mechanism could achieve the goal of rapid picking of pineapple fruits, which can provide a solution for the mechanization of pineapple picking.