Design and experiment of collocated-copying and semi-low-height planting-unit for corn precision seeder

Aiming at the problem of poor uniformity of row spacing, seed spacing and planting depth caused by traditional planting units which couldn't meet the needs of collocated-copying and low planting height simultaneously, a new type of planting unit was designed. Compared with traditional planting units with planting height of 400-440 mm, the planting height of the new unit was only 280 mm and at the same time the planting-unit had the function of collocated-copying. The configuration parameters of crucial components, such as the diameter of copying wheel, the length of copying wheel bracket, the length and tilt angle of anti-block of copying wheel, and etc, were analyzed and determined. The minimum and maximum planting depth was 40 and 90 mm, respectively. So the planting-unit had a greater adjustment range of planting depth and could meet the needs of precision planting in most cases. Field experimental results indicated that the new designed unit could accomplish corn precision planting, and the qualified index of seed spacing, reseeding index, miss planting index, coefficient of variation of spacing and uniformity of planting depth were 94.8%, 2.9%, 2.3%, 15.1% and 88.3% respectively, and all of which were obviously better than the corresponding indexes of the traditional planting unit with high planting height.