大方捆机玉米秸秆切碎装置设计与试验

Design and Experiment of Corn Stalk Chopping Device for Large Square Baler

摘要:

针对大方捆机切碎装置在大喂入量工况下剪切功耗高、切碎长度偏长且离散等问题,以自制大方捆玉米秸秆切碎装置为研究对象,开展作业参数多目标优化。基于动、定刀剪切结构对秸秆切碎过程受力特征及切碎间隙对剪切状态的影响进行分析,并通过单因素试验确定切碎转子转速、喂入速度和切碎间隙取值区间。采用Box-Behnken响应面法建立作业参数与平均切碎长度、平均作业扭矩之间的二次回归模型,分析多因素及其交互作用对切碎质量与能耗的影响规律。结果表明,各因素对综合性能的影响由大到小为：切碎间隙、切碎转子转速、喂入速度。经多目标优化,确定最优参数组合为：切碎转子转速74 r/min、喂入速度1.4 m/s、切碎间隙66 mm;在该条件下,模型预测平均切碎长度为77.56 mm,平均作业扭矩为66.13 N·m。与典型高负载工况（切碎转子转速68 r/min、喂入速度1.6 m/s、切碎间隙56 mm）相比,平均切碎长度降低8.99%,平均扭矩降低21.5%。田间验证试验结果表明,优化参数下实测平均切碎长度为83.32 mm,与预测值相对误差为7.4%,作业过程稳定,满足大方捆打捆作业要求。

Abstract:

Aiming to address the problems of high cutting power consumption,excessive chopped length,and poor length uniformity of the chopping device of a large square baler under high feeding-rate conditions,a self-developed experimental bench for chopping corn stalks in a large square baler was used to carry out multi-objective optimization of operating parameters. Based on the shearing structure composed of moving and fixed knives,the force characteristics of the stalk chopping process and the effect of chopping clearance on the shearing state were analyzed,and the reasonable ranges of chopping rotor speed,feeding speed,and chopping clearance were determined through single-factor experiments. The Box-Behnken response surface method was employed to establish quadratic regression models between the operating parameters and the average chopped length as well as the average operating torque,and to analyze the effects of multiple factors and their interactions on chopping quality and energy consumption. The results showed that the order of influence of the factors on the overall performance,from the greatest to the least was as follows: chopping clearance,chopping rotor speed,and feeding speed. Through multi-objective optimization,the optimal parameter combination was determined as chopping rotor speed of 74 r/min,feeding speed of 1.4 m/s,and chopping clearance of 66 mm. Under these conditions,the model predicted an average chopped length of 77.56 mm and an average operating torque of 66.13 N·m. Compared with a typical high-load operating condition (chopping rotor speed of 68 r/min,feeding speed of 1.6 m/s,and chopping clearance of 56 mm),the average chopped length was reduced by 8.99%,the average torque was reduced by 21.5%. Field validation tests showed that under the optimized parameters,the measured average chopped length was 83.32 mm,with a relative error of 7.4% from the predicted value. The operation process was stable and met the operational requirements of large square baling.