To address the challenges of low precision and suboptimal seeding efficiency in existing rapeseed seed metering wheels equipped with shaped grooves, the traditional rectangular grooves were redesigned into trapezoidal forms to enhance overall seeding performance. Building upon this modification, a precision metering wheel featuring trapezoidal-shaped grooves capable of dispensing (3±1) seeds per hole was developed, and its fundamental structural parameters were established. Theoretical analysis combined with experimental validation identified four key factors influencing seed filling performance: the inclination angle of the seed guide shaped groove, the rotational speed of the metering wheel, the width of the trapezoidal groove, and the non-standard opening width. A response surface methodology was employed to examine the effects of these factors on the qualification rate, reseeding rate, and missed seeding rate. Results indicated that the qualified seeding rate was 94.17%, the reseeding rate was 3.92%, and the missed seeding rate was 1.91% under optimal parameters. Field tests confirmed that the device met the agronomic requirements for rapeseed sowing. This study serves as a reference for the design of precision sowing devices for rapeseed.

To address the errors associated with the application of existing Discrete Element Method simulation parameters in roller-type precision seeders, this study focused on calibrating the key contact parameters of the ‘Xinhe No. 1’ coated confectionary sunflower seeds, so as to provide a reliable simulation foundation for the optimization of the seeders. Through dynamic stacking angle experiments and comparative trials involving confectionary sunflowers (including Xinhe No. 1) and oil sunflowers with significantly different physical properties, the optimal working conditions for the rotating drum were determined as a rotation speed of 10 r/min, 304 Stainless Steel as the inner wall material, and a filling ratio of 30%. The study also clarified the variation patterns of the dynamic stacking angle. Physical experiments were conducted to measure the static friction coefficients, restitution coefficients, and inter-seed restitution coefficients between Xinhe No. 1 seeds and three materials: 304 Stainless Steel, Q235 Steel, and ABS Plastic. The physical dynamic stacking angle was obtained via a rotating drum experiment. A single-factor experiment was used to determine the range of simulation parameters, and a second-order orthogonal experiment was conducted using Design-Expert software to optimize contact parameters with the physical dynamic stacking angle as the target. The parameters were subsequently validated using the Discrete Element Method (DEM) simulation software EDEM 2022.3, hereinafter abbreviated as EDEM simulations. Finally, rolling friction coefficients between seeds and Q235 Steel and ABS Plastic were obtained through both simulation and physical experiments using alternative contact materials. The results showed that the static friction coefficients between Xinhe No. 1 and 304 Stainless Steel, Q235 Steel, and ABS Plastic were 0.32, 0.36, and 0.25, respectively; the restitution coefficients were 0.42, 0.39, and 0.32; and the rolling friction coefficients were 0.012, 0.011, and 0.010. The measured values of the inter-seed static friction coefficient, restitution coefficient, and rolling friction coefficient were 0.31, 0.43, and 0.010, respectively. The relative error between simulated and physical stacking angles was <1.5%. Calibrated DEM parameters for Xinhe No. 1 coated sunflower seeds provide a theoretical basis for optimizing the design of sunflower precision seeders.