A Seedbed Clearing and Shaping Device for Dry Direct-Seeded Rice

The soil in some areas of northern China is heavy owing to the presence of clay and stones, which significantly affects the normal operation of a planter as well as the growth of rice. In this regard, this study proposes a seedbed clearing and shaping device for dry direct-seeded rice, which can be used to remove stones in the seeding area, break soil blocks, for soil leveling, and groove forming. The overall structure and roller of the proposed device was developed based on theoretical calculations, discrete element modeling (DEM) simulations, and field tests. The soil-mixing tooth was distributed on the roller based on the double-helix rule, and the two sides of the helix were configured according to the right-hand and left-hand. Subsequently, DEM was used to develop a 3(3) box-bench design. According to the agronomic requirements and operating speed ratio, the forward speed was set to 0.5 m/s. Furthermore, the optimization parameters combination of the device obtained by simulation experiments was: forward speed 0.5 m/s, soil depth 61 mm, and rotation speed 110 r/min, which obtained a stone removal rate of 85.65%, stone removal efficiency of 35.47 pieces/m, operating resistance of 719.23 N, and torque of 174.89 Nm. The field verification test results indicated that the stone removal rate was 77.23% under the optimization parameters combination, and the mean relative error of the simulated experiments value was 8.42%, which showed that the performance of the proposed device functioned stably and reliably, thereby providing a high-quality seedbed for sowing and rice growth. The developed device represents a useful solution for the seedbed clearing and shaping.