Aiming at the lack of accurate and reliable discrete element simulation parameters for the design of buckwheat metering devices and seeders based on the discrete element simulation method, an accurate buckwheat seed model was obtained by calibrating the discrete element simulation parameters. In this study, buckwheat seed particle models were established based on the manual and automatic filling methods. In order to improve the accuracy of the models, discrete element simulation parameters were calibrated, and the static cylinder-lifting test and dynamic seed-metering test were used to verify the simulation results. A 3D model of buckwheat seed was obtained using the CT scanning method, and a manual filling 7-sphere particle model and an automatic filling multi-sphere particle model were established. The physical parameters and contact parameters were measured using the uniaxial compression test, the drop test, and the friction coefficient measurement test. The Plackett–Burman test and steepest ascent path were used to obtain the optimal parameter combination based on the static cylinder-lifting test. We conducted dynamic seed-metering tests using the two particle models under the optimal parameter combination. The results show that, compared with the measured values of stacking angle, the relative errors of the simulation values of the manual filling 7-sphere and automatic filling 36-sphere particle models are 1.04% and 0.50%, respectively. When the rotation speed range of the seeding wheel is 20~60 r/min, the average relative errors between the simulated value and the measured value are 15.85% and 4.69%, respectively. When the effective working length range of the seeding wheel is 20~40 mm, the average relative errors between the simulated value and the measured value are 22.18% and 9.07%, respectively. Regardless of whether the manual filling 7-sphere or the automatic filling 36-sphere particle model of buckwheat seed was used for static motion parameter simulation or dynamic motion simulation, the automatic filling 36-sphere particle model has a higher accuracy. The buckwheat seed particle model established in this study will provide support for the design of buckwheat special seed-metering devices and improve the quality of buckwheat mechanized sowing operation.

Cultivating the soil is a necessary measure to ensure the growth of potatoes, and it has a significant impact on potato yield. In this study, a soil cultivator with a textured shovel wing was designed to address the problem that soil cultivators have poor working performance. Based on a combination of discrete element simulation and a digital soil trench verification test, the effects of the structure parameters of the surface textures on the traction resistance and soil fragmentation rate of the soil cultivator with a textured shovel wing were studied. These parameters were optimized to provide a basis for the design of the soil cultivator. The main research results of this paper are as follows. (1) The factors influencing the traction resistance of the soil cultivator were as follows: blade penetration angle > convex hull distance > convex hull diameter. The convex hull diameter was the main factor affecting the soil fragmentation rate. The traction resistance of the soil cultivator with a textured wing was reduced by 9.49%, and the soil fragmentation rate was increased by 10.67%, showing that the quality of soil cultivation was significantly improved. (2) The best parameters for the texture structure of the shovel wing were a blade penetration angle of 26°, a convex hull diameter of 34.4 mm, and a convex hull distance of 28.5 mm. (3) The relative errors between the simulation and the soil trench test for the traction resistance and the soil fragmentation rate were 2.60% and 13.97%, respectively. This study can provide technical support for the design of soil cultivators and is of great significance in improving the quality of soil cultivators.

When the potato planter works on sloping field, it will cause problems such as poor film mulching quality due to the difference in volume of soil covering both sides of the discs and the inconvenient adjustment of the soil covering disc. The soil covering device with linkage and differential adjustment was designed to improve the mulching quality. The main research content includes explaining the structure and principle of the soil covering device and analyzing the structural parameters of the adjustment mechanism. The field experiment was completed to verify the performance of soil covering device, which takes the stability coefficient and uniformity coefficient of the volume of covering soil as factors. The result shows the following: (1) The volume of covering soil changes exponentially with the angle of the disc through data fitting, which can standardize the angle of covering disc; and (2) when the angle of disc is 30° and 60°, respectively, the uniformity coefficient of volume of covering soil is lower than 1.4, which has premium soil covering quality. When the angles of the discs on both sides differ greatly, the stability coefficient of volume of covering soil is 0.41, which can meet the requirements of the mulching quality of potato planter. This research provides the technical support for high-quality potato planting.