Analysis and experiments of the seed feeding performance of air-suction roller dibbler for peanuts

Abstract: An air-suction drum-type dibbler has been widely used for peanut seed feeding in recent years. However, the seeds cannot accurately fall into the seed guiding mechanism, due to the missed sowing and rebroadcast in the dibbler. In this study, the seed feeding trajectory was optimized to adjust the opening position of the cover edge in the dibbler and the installation angle of the seed guiding mechanism. A dynamic model was also established to clarify the variation in the seed feeding trajectory for the stage when the seeds left the cover of the dibbler to enter the seed guiding mechanism. The seeding performance of the dibbler cover and the seed guiding mechanism was then optimized to determine the installation angles using EDEM software. The best seeding performance was achieved in the contact with the seed stopper of the seed separation tray when the seed was separated from the edge of the dibbler cover. A three-factor and three-level combination test was carried out on the seed metering test bed. Among them, the test factors were the installation angle of the dibbler cover and the seed guiding mechanism, as well as the forward speed of the machine, while the qualified rate of the seed spacing, the missed seeding rate, and the rebroadcast rate were taken as the test indicators. The results showed that the best seeding performance was achieved, where the installation angles of the dibbler cover and the seed guiding mechanism were 17.10° and 11.18°, respectively, while the working speed of the machine was 3.85 km/h. Correspondingly, the qualified rate of seed spacing was 95.37% during this time. A reasonable range of installation parameters was determined, according to the influence of the installation angle of the dibbler cover and seed guiding mechanism on the seeding trajectory. Specifically, the larger the installation angle of the dibbler cover was, the more stable the seed cover separation process was; The smaller the installation angle of the seed guiding mechanism was, the easier the seeds fell into the effective area of the seed guiding mechanism. Therefore, the comparison test was then performed on the installation angle of the dibbler cover and seed guiding mechanism of 20° and 10°, respectively. It was found that the seeding performance of the optimal installation combination was significantly improved than that of the installation combined with the installation angle of the dibbler cover of 20° and the installation angle of the seed guiding mechanism of 10° under the forward speed of 3.00-5.00 km/h. More importantly, there was a more significant seeding performance in the optimized dibbler, particularly with the acceleration of the forward speed of the machine. Huayu 25 peanut seeds were selected to verify in the field experiment. Once the standby speed was stable, the length of the single ridge was counted as the planting in two rows within 15 m. Each experiment was repeated three times. There was flat and light sandy soil terrain in the experimental field, where the soil moisture content was 13%-15%. The field tests showed that the optimal adaptability was achieved to adjust the installation angle of the dibbler cover to 17.10°, the installation angle of the seed guiding mechanism to 11.18°, while the forward speed of the machine and tool within the range of 3.05-4.65 km/h. The qualified rate of seed spacing was greater than 89%, whereas, the missed sowing rate and replay rate were less than 7%, and 5%, respectively, fully meeting the requirements of precision sowing of a single peanut.