Design of crawler type corn combine harvester for whole plastic film mulching on double ridges in arid regions

The technology of corn whole plastic film mulching on double ridges has become the main production mode of corn planting in arid regions of Northwest China, which provides an effective technical way for corn yield stabilization. Compared with the vertical roller corn combine harvester, the traditional horizontal roller corn combine harvester is not easy to achieve both ear and stalk under this cultivation mode. The existing vertical roller corn combine harvester has some problem such as unstable walking on ridges, high ear loss rate on cutting platform, and inconsistent quality of stalk cutting with feeding requirements when harvesting in the field. In order to solve the stability of the ridge harvester, we adopted a crawler type walking device, and then designed a vertical corn harvester cutting platform to achieve the recovery of corn stalk while harvesting corn ears. Asymmetric vertical snapping roller double roll harvesting structure was designed in this study. It could meet the requirements of corn full-film double ridges furrow sowing. And both ear and stalk could harvest at the same time, which can improve the utilization rate of straw. And the harvesting mechanism of vertical corn harvester cutting platform gap clamping - inclined feeding - sliding picking was summarized. The orthogonal combination experiment of secondary rotation was carried out by using a vertical heading test prototype, taking the forward speed of the machine, the rotation speed of drive sprocket, the diameter of snapping roller and the rotation speed of cutter shaft as the influencing factors. And the ear loss rate and the qualified rate of cutting stalk were the evaluation parameters. Through the Design-Expert 8.0.6 data analysis software, the mathematical regression model of each influencing factor and index was established, the relationship between the significant factor and the evaluation index was analyzed, and the test parameters were optimized. The optimum parameters of the optimization model were determined as follows: when the forward speed of the machine was 3.8 m/s, the rotation speed of the drive sprocket was 1 150 r/min, the diameter of snapping roller was 82 mm, and the rotation speed of cutter shaft was 1 650 r/min, the ear loss rate was 2.61%, and the qualified rate of the cutting stalk was 92.81%. The optimum model was close to the average ear loss rate of 2.8% and the average qualified rate of the cutting stalk of 93.1% obtained from field validation test, which met the requirements of corn harvest in arid regions of China. © 2019, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.