Design and test of a positive-negative pressure quinoa precision seed-metering device with a disturbed seed-filling mechanism

Aiming at the problem of difficulties in seed filling and seed cleaning caused by the small specific gravity, small size, and irregularity of quinoa seeds, a positive-negative pressure precision seed-metering device for quinoa seeds with a disturbed seed-filling mechanism was designed. The disturbed seed-filling mechanism can improve the seed-filling performance of the precision seed-metering device and reduce the power consumption required by the forced-draught fan. Positive pressure seed cleaning can solve the problem of pore blockage caused by small and light quinoa seeds and improve work stability. Taking Jili No. 3 seed as the research object, simulation analysis of the flow field in the air chamber of the precision seed-metering device was carried out by the Fluent 2021 R1 software. The influence of seed-sucking hole structure parameters (shape and number of seed-sucking holes, inclination angle of seed-sucking holes, and diameter of seed-sucking holes) on the flow field was analyzed by a pressure nephogram and a velocity vectogram. The optimal parameter combination was obtained as follows: a circular-cone-type shape of the seed-sucking hole, a number of 20 seed-sucking holes, a 70° inclination angle of the seed-sucking hole, and a 1 mm diameter of the seed-sucking hole. EDEM 2020 software and orthogonal test were used to optimize the design of the disturbed seed-filling mechanism. The influence of structural parameters of the disturbed seed-filling mechanism (groove radius of the disturbed seed-filling mechanism (GRDSM), arc of the disturbed seed-filling mechanism (ADSM), and position angle of the disturbed seed-filling mechanism (PADSM)) on the qualified index (I_q) of scooping seeds was analyzed. The optimal parameter combination was obtained: 1.3 mm GRDSM, 140° ADSM, and 25° PADSM. With the help of the JPS-12 test-bench, a response surface test was carried out with the qualified index (I_q), the miss index (I_miss), and the multiple index (I_mul) as test indices, and the seed-sucking negative pressure, the seed-metering device rotation speed, and the seed-falling height as test factors. The optimal working parameter combination was obtained: –3.0 kPa seed-sucking negative pressure, 15 r/min seed-metering device rotation speed, 100 mm seed-falling height. Validation tests were carried out on the optimized seed-metering device, and the results showed that the I_q was 82.5%, the I_miss was 6.5%, and the I_mul was 11%, which met the index requirements in JB/T 10293-2013 Technical conditions of single seed (precision) seeder. The results of this study can provide a reference for the design of machinery for the precision seeding of small seeds such as quinoa.