异速圆盘动态支撑式玉米秸秆粉碎装置设计与试验

Design and Experiment for Dynamic Supporting Type Maize Straw Chopping Retention Device with Different Rotation Speeds of Disc Blade

摘要:

针对玉米秸秆粉碎过程中秸秆力学和能耗变化规律不明确，限制秸秆粉碎还田质量提升，不利于秸秆还田技术在东北黑土区推广应用的问题，本文基于异速圆盘动态支撑式玉米秸秆粉碎装置和秸秆受力状态，将玉米秸秆粉碎全过程分为秸秆捡拾阶段、秸秆升举输送阶段和入侵粉碎阶段，建立秸秆各阶段受力数学模型，确定其关键影响参数及范围。以捡拾粉碎刀转速、对数螺线支撑圆盘刀滑切角和捡拾粉碎刀与对数螺线支撑圆盘刀间的传动比为试验因素，选取秸秆最大破碎力、滑切切割功耗和滑切冲量为试验指标，应用有限元分析方法研究试验因素对试验指标的影响规律。结果表明，捡拾粉碎刀转速为1950 r/min、对数螺线支撑圆盘刀滑切角为40°和捡拾粉碎刀与对数螺线支撑圆盘刀间的传动比为0.5时，秸秆最大破碎力、滑切切割功耗和滑切冲量分别为101.71 N、1049.42W和0.032N·s。田间验证试验结果表明，滑切切割功耗为1150.43W，与模型预测值误差为9.63%，秸秆粉碎长度合格率为93.34%，满足行业标准要求。

Abstract:

In the Northeastern China, due to unclear change principles of force and energy consumption during maize straw chopping process, the lower maize straw chopping quality is acquired which is not conducive to the decomposition of chopped straw because of the cold weather. This limits the application and promotion of maize straw retention technology. However, the area of the cropland with obstruction factors, such as poor soil, soil acidification is about 13 million hectares, which seriously affects the food security in China. Therefore, in order to solve above problems, the dynamic supporting type maize straw chopping retention device with different rotation speeds of disc blade was designed, The maize straw chopping retention device mainly included the collecting and chopping device, which was used to collect and transfer the maize straw in the filed surface, and the logarithmic spiral supporting disc device, which was used for dynamic support for the chopping of the maize straw combined with collecting and chopping device. In addition, the logarithmic spiral supporting disc blade was designed based on the slidecutting principle and the angle, thickness and length of the cutting edge and bent angle for the collecting and chopping blade were 20°, 3 mm, 45 mm and 40°, respectively. The rotation radius of the collecting and chopping blade and the logarithmic spiral supporting disc blade all were 250 mm. According to the force status of maize stalk in the chopping process, the chopping process was divided into three stages: collecting stage, transformation stage and chopping stage. In each stage, the force equation of maize straw was established, and it was found that the angular velocity of collecting and chopping blade and logarithmic spiral supporting disc blade and slide-cutting angle of the logarithmic spiral supporting disc blade had the obvious effect. Based on the actual operation conditions and theoretical analysis, the rotation speed of collecting and chopping blade, transmission ratio between collecting and chopping blade and the logarithmic spiral supporting disc blade and slidecutting angle of the logarithmic spiral supporting disc blade were selected as the test factors, and the peak straw breaking force, slide-cutting energy consumption and slidecutting momentum were selected as the test indexes. A Box-Behnken test was executed based on the finite element analysis method because the peak straw breaking force and slide-cutting momentum in actual field experiment was impossible to be measured. The results showed that the primary and secondary factors that affected the peak straw breaking force, slidecutting energy consumption and slidecutting momentum was transmission ratio, slidecutting angle of the logarithmic spiral supporting disc blade and rotational speed of the collecting and chopping blade. When the rotational speed of the collecting and chopping blade. slidecutting angle of the logarithmic spiral supporting disc blade and transmission ratio were 1950 r/min, 40°and 0.5, which was the optimal parameter combination, the peak straw breaking force, slidecutting energy consumption and slidecutting momentum were 101.71N, 1049.42W and 0.032N·s, respectively. The field validation experiment results showed that the slide-cutting energy consumption was 1150.43 W, the error with the model predicted value was 9.63% and the maize straw chopping pass ratio was 93.34%, which satisfied with the national standard. The research can provide references for the design and optimization of the maize straw chopping machine.