Abstract:Aiming at the demand for precision seeding of wheat and the uniformity seed spacing, a precision seed metering device with staggered hook-tooth was designed. The hook tooth were used to grab seeds orderly, and the staggered arrangement of the teeth allows the falling seeds to form a staggered and ordered surface, reducing collision and overlap between seeds. The key structural parameters and curve profile of the hole were determined by analyzing the seed postures during seed-filling process. The effects of the rotational speed of the seeding wheel and the angle of the seed-filling area on the operation performance were analyzed by using discrete element method EDEM. The simulation results showed that the speed of the seeding wheel had a significant effect on the seeds postures. The increase in the angle of the seed-filling area was conducive to improving the seed-filling performance. However, too large an angle of the filling area may cause the successfully filled seeds to fall out of the hole. On this basis of that, laboratory tests were conducted. Qualified rate, single rate, and multiple rate were used as performance indicators. Rotational speed of seeding wheel, height of seed-filling area and speed ratio of brush/seeding wheel were the test factors. The regression equations of the qualified rate, single rate, and multiple rate were obtained. Through the regression equations, it was found that the optimum performance of the seed metering device was achieved. A validation tests were carried out using the optimal parameters at the seeding wheel speed of 18r/min, the height of seed-filling area of 73mm, and the speed ratio of brush/seeding wheel of 2.5. The qualification rate was 90.36%, and the single rate was 87.26%, which verified the reliability of the regression model. Comparison tests were carried out by selecting the seed metering device commonly used in wheat planter. A high speed camera was used to capture the process of seed dropping. The metering device designed realized the staggered and orderly seeds falling, which improved the uniformity of seed distribution. The research result can provide theoretical support for the development of wheat precision seeding technology.
