Design of precision pneumatic cup seed-metering device for potato

Aiming at the limitation of further improving the advance speed of the cup-belt metering device and the large power consumption of the pneumatic seed-metering device in planting potatoes, a kind of precision pneumatic cup seed-metering device was designed. Precision pneumatic cup seed-metering device for potato was mainly composed of roller, cup, seed box, hollow shaft, pneumatic separator, compression spring, sprocket, seed clearing air tube and other components. The negative pressure air flow entered the air chamber formed by the roller through the hollow shaft at work. The roller rotated by the power provided by the sprocket, which drove the cup to rotate and take seeds from the seed box. The seed potato was adsorbed on the cup by the support force provided by the cup and the adsorption force provided by the negative pressure to complete the seed filling process, and the cup stirred the seed potato layer at the same time to avoid the overhead phenomenon of the seed potatoes. The seed potato continued to move with the roller by the carriage of the cup and the air flow. When the number of seed potatoes taken by the cup was more than one, the excess seed potato was blown off by the positive pressure air flow and the cleaning process was completed. The seed potato moved gradually to the planting area with the roller by the combined action of negative pressure air flow and supporting cup. The air flow was blocked by the pneumatic separator from the inside of the roller, and the negative pressure adsorption force of the seed potato disappeared. The seed potato fell into the furrow formed by the furrow opener under the action of gravity. Through theoretical analysis and calculation, parameters of key parts of seed-metering device were determined. The range of negative pressure needed by seed-metering device was determined by theoretical calculation and experiments. It was carried out that the hole diameter and the size of the cup were designed and calculated. In order to obtain the optimum parameters of groove angle and the movement of seed potatoes in the seed filling process, the simulation experiment was carried out by using the discrete element simulation software EDEM. It was determined that the missed filling rate of the cup was low when the groove angle was at 62°. The structural parameters of the roller, the number of cups and the installation parameters of the seed clearing air tube were determined by theoretical analysis. In order to determine the optimum operation parameters of precision pneumatic cup seed-metering device for potato, negative pressure, seed cleaning speed, hole diameter and rotational speed were taken as test factors, and the missing rate, qualified rate were taken as test indices. The performance test of the seed-metering device was carried out by Box-Behnken test method, and the effect of missing rate and qualified rate was obtained. The primary and secondary order of influence on missing rate and qualified rate were negative pressure, rotational speed, hole diameter and seed cleaning speed. The data processing software Design Expert 8.0.6 was used to optimize the parameters. With the missing rate, qualified rate as the test indices, the negative pressure was 8.92 kPa, the seed cleaning speed was 32.25 m/s, the hole diameter was 18.34 mm and the rotational speed was 19.92 r/min. The missing rate predicted by the model was 3.64% and the qualified rate was 91.9%. The experimental results showed that the results were consistent with the optimization results. The related research can provide reference for the research of precision sowing technology in potato.