Parameter optimization and experiment of the negative pressure precision seed-metering device for wheat

In order to ensure the most reasonable distribution of wheat seeds in the field to improve seeding quality and uniformity, a set of negative pressure precision seed-metering device was designed, which shares a hollow shaft. Every seed-metering device can sow two rows of wheat. By the STAR-CCM+, the analysis of nephogram, vectogram and streamline graph showed that more ideal structural parameters of the seed-metering device are 0.5 mm width of the slit sucking seed (WSS), 150-200 mm diameter of the seed-metering disc (DSD), 2.0 mm axial depth of air chamber in the seed-metering disc (ADS), and arc-shaped cross-section shape of the ring groove sucking seed (CSGS). Single-factor test on the JPS-12 test-bed analyzed the influence of the CSGS, WSS, DSD, and ADS on the qualified index (I_q), multiple index (I_mul), miss index (I_miss) and coefficient of variation of qualified seed spacing (CV). Through the orthogonal on the JPS-12 test-bed, it is found that the influence of vacuum negative pressure and seed-metering device shaft speed is significant on the I_q, I_miss and I_mul. Based on these, the structural parameters of the seed-metering device were optimized. The DSD is 180 mm, the WSS is 0.7 mm, the ADS is 2.5 mm, and the CSGS is arc-shaped. The optimization seed-metering device was tested on the JPS-12 test-bed. The I_q is 86.66%, the I_miss is 5.09%, the I_mul is 8.25%, and the CV is 24.50%. These testing results fully coincide with the standard JB/T 10293-2013 Specifications of single seed drill (precision drill). The seed-metering device meets fully the requirements for wheat precision seeding.