玉米梳齿摘穗单体机构设计与试验

针对现有玉米收获机摘穗机构行距固定,难以实现按需调整以适应各类行距的问题,设计了一种玉米梳齿摘穗单体机构。该机构主要由梳齿滚筒、梳齿杆、梳齿杆安装座及传动轴等组成。相邻两梳齿杆的间隙小于玉米果穗大端的直径且大于玉米茎秆的直径,利用冲力将玉米果穗强制摘下。初步试验表明,玉米梳齿摘穗单体机构能够可靠地完成玉米摘穗作业。在玉米籽粒含水率为35.5%,玉米梳齿摘穗单体机构转速为110~170 r/min时,工作状况较好,籽粒破碎率的范围为0.14%~0.48%,落地籽粒损失率范围为0.03%~0.17%。正交试验结果表明,当转速为110 r/min,梳齿杆圆弧半径为240 mm,梳齿传动轴位于果穗大端下方100 mm时工作情况较好,籽粒破碎率为0.09%,落地籽粒损失率为0.04%,果穗损失率为1.96%。

Design and experiment of corn stripping monomer mechanism

Abstract: Aiming at the row width of corn head was fixed and could not be adjusted by the corn row spacing. The corn stripping monomer mechanism was designed. The mechanism mainly consisted of a stripping roller, a stripping bar, a stripping bar mounting seat, and a transmission axis etc. The space between the adjacent stripping bars was less than the diameter of the ear big end and bigger than the diameter of the corn stalks. The machine moved forward while the stripping roller rotated. When the stripping bars touched the big end of the ear, the ear was picked off from the plant by the force of the impact. The space between the stripping bars, the rows of the stripping bars, the diameter of the stripping mechanism, and the height from the axis to the ear big end were determined. Mechanical analysis was done to explore the best space between the stripping bars. Theoretical calculation was conducted to obtain the best rows, the diameter of the stripping mechanism, and the height. After the ear was picked off from the plant, the ear was thrown backwards and collected. The shape of stripping bars was important to reducing the ear loss rate. In order to obtain the best diameter of the stripping bars, the motion analysis was done in the corn picking-off process. If the ear was thrown backwards, the coordinate of the ear should be less than the coordinate of the stripping bar's outer edge point. The diameter of the stripping bar was determined by the calculation. The preliminary results showed that the corn stripping mechanism could reliably finish the ear picking-off process. The plants were installed on the walking trolley by the fixture and fed into the corn stripping mechanism. Single factor tests of rotational speed were done. The tests took the grain broken rate, grain loss rate, and ear loss rate as index. The tests were done when the grain moisture content was 35.5%. The single factor test of rotational speed was done in five levels such as 80, 110, 140, 170, and 200 r/min. The corn stripping mechanism worked well when the rotational speed was 110-170 r/min. The grain broken rate was 0.08%-0.48%, and the grain loss rate was 0.03%-0.17%. It was comprehensively considered that the best speed range was 110-170 r/min. The orthogonal test was done to explore the best working conditions in the field. Three factors were considered in the orthogonal test including rotational speed, bars shape, and the distance from the axis to the ear. The rotational speed selected three levels including 110, 140, and 170 r/min. The diameter of the stripping bar selected three levels including 240, 370, and 500 mm. The distance from the axis to the ear selected three levels including 100, 120, and 140 mm. The orthogonal test showed that the stripping mechanism worked best when the rotational speed was 110 r/min, the diameter of the stripping bars was 240 mm, and the distance was 100 mm from the axis to the ear. The grain broken rate was then 0.09%, the grain loss rate was 0.04% and the ear loss rate was 1.96%.