No abstract

To improve the problem of low seeding efficiency facing the single-row planting mode traditionally used in China, this study aimed to design a novel three-row pneumatic precision metering device. The working principle and main structure were introduced in the paper. The three main factors affecting the seeding performance comprised of vacuum pressure, angular velocity of the metering tray, and taper angle of the sucking hole. A Box-Behnken experiment design having the qualified index and missed seeding index as the experimental index was used, and the results indicated that optimal performance of the metering device was achieved when the vacuum pressure was 2.16 kPa, the angular velocity of the metering tray was 29.43 rpm, and the taper angle of the sucking hole was 61.51°. The qualified index of the inner, middle, and outer ring was 95.12%, 94.68% and 94.24% respectively, while the missed seeding index of the inner, middle, and outer ring was 3.67%, 3.12% and 2.58% respectively under the optimal combination of parameters. The bench test results were basically consistent with the optimized results. This paper can provide support for the design of a three-row pneumatic precision metering device for Brassica chinensis.

In view of the low seeding efficiency and precision of seeders used for Brassica chinensis in China, a new double-row pneumatic precision metering device for Brassica chinensis was designed, fabricated, and evaluated. With the characteristics of small size and high sphericity of Brassica chinensis seeds in mind, the structure and key dimensions of the metering plate were determined, and a force analysis of the seed-filling process was carried out. The negative pressure (NP), angular velocity (AV) of the metering plate, and cone angle (CA) of the suction hole were selected as the main influencing factors of the experiment. In order to explore the influence of each single factor and the interaction between factors on the seeding performance, a single factor experiment and a central composite design (CCD) experiment were designed, respectively, and the experimental results were analyzed by analysis of variance (ANOVA). After optimizing the main influencing factors such that the target of the qualified index (QI) was greater than 94% and the miss index (MI) was less than 2.5%, it was found that when CA was 60°, NP was 1.55–1.72 kPa, and AV was 1.1–1.9 rad/s, the seeding performance was excellent. The bench verification results of seeding performance (94% ≤ Q ≤ 100%, 0 ≤ M ≤ 2.5%) and the coefficient of variation (CV) of seed mass (CV of seed mass in outer and inner circle: 5.15%; CV of total seed mass: 8.60%) under the condition of parameter optimization were analyzed; as a result, the accuracy of the parameter optimization was confirmed.

No abstract

The airflow cylinder sieve directly affects the harvesting effect as one of the main components of the rice combine harvester. The process of grain separated from threshed rice mixture is a multi-physical random pattern. This paper constructed accurately the components particle models, and reproduced the screening process of mixture via CFD-DEM (Computational Fluid Dynamics and Discrete Element Method). Objectives of this work are to better understand the impact of airflow velocity, aperture and deflectors of cylinder sieve on separation effect of the mixture in an airflow cylinder sieve device. The optimal working parameters of sieve were developed by the OED (Orthogonal Experiment Design) and the weight of the index method. The simulations result show that airflow velocity and aperture have an impact on the loss ratio and efficiency; deflectors have implications on efficiency. It is beneficial for separation of grain from the mixture with the airflow velocity, the aperture and deflectors are of 11m/s, 11mm, and two turns, correspondingly. The experiments result carried out on the test bench with real threshed rice mixture and agree with simulations, which proved the feasibility of the results. This paper provided basic data for the design of screening unite of rice harvester's equipment.