Design and experiment of double-storage turntable cotton vertical disc hole seeding and metering device

Current vertical disc hole seed-metering device has been limited to the low seed picking performance and high damage rate in recent years. In this study, a double-chamber turntable and vertical disc-hole seed-metering device was designed to combine the cotton precision hole sowing. First of all, the silo structure of seed picking and seeding was introduced to clarify the different work processes in the double warehouse, namely the completion of seed filling and clearing in the seed taking warehouse, then passing the cotton seed to the seeding warehouse through the warehouse transfer area, finally realizing the whole workflow of seeding in the seeding area. A double-bin separated structure was also designed for seed-carrying to reduce the damage of cotton seed. Secondly, a new equation was established for the time in a single seeding unit, thereby determining the way to take the side lying during precision hole-sowing. Specifically, the diameter of the seed disk was 220 mm, the length, width, and height of the seed hole was 9.2 mm×5.2 mm×4.7 mm, as well as the number of seed holes was 16. The seed tray was adopted the working mode of seeding from one side and different sides, in order to ensure that the seeding chamber was not interfering with the precision of seeding during the seed extraction stage. As such, the placement angles of the seed metering cavity and seed holes were staggered by a certain angle during design. Correspondingly, the cotton seeds were slid into the seeding chamber in time during the warehouse transfer stage, where the damage rate of cotton seeds was reduced significantly. Specifically, the steepest drop line was selected to calculate the falling angle of seeds, where the falling angle was determined to be 48°. Further, a mechanical model for the injury to the seed was established to analyze the force and movement state of cotton seeds in the warehouse transfer area, where the minimum seeding gap was 1.47 mm. As such, the optimal matching parameters of relevant components were determined to reduce the damage rate in the warehouse transfer stage. A mechanical model was also established to clarify the effect of seed hole offset angle and disc rotation speed on the seed picking performance in the seed collection area. Finally, Design Expert 8.0 software was used for the Box Benhnken design, where the rotating speed of the seed disk, the offset angle of the socket hole, and the seeding gap were the influencing factors. Subsequently, a three-factor three-level quadratic regression orthogonal test was carried out to optimize the single grain rate and the broken rate. Experiments show that the primary and secondary influencing factors of single-grain rate in the process of seeding were the offset angle of seed hole, the seeding gap, and the speed of seed disk. The better seeding performance was achieved in the combination of the seed disk rotation speed 23.9 r/min, seed hole offset angle of 31.7°, seed metering gap of 2.08 mm, At this time, the single-grain rate was 96%, and the damage rate was 0.13%. Field experiments were also performed to verify the optimal combination. Correspondingly, the single-grain rate was 94.3% and the breakage rate was 0.09%, fully meeting the agronomic requirement of cotton precision sowing. This finding can provide a strong reference for the structural design of vertical disc hole seeding and metering device for cotton.