Dynamic analysis on seeds pick-up process for vacuum-cylinder seeder

3-D models of rape seeds and vacuum cylinder were established to analyze the influence of working parameters on pick-up performance of vacuum-cylinder precision seeder. In constant pressure boundary condition, software Fluent was used to calculate the suction forces action on seeds in the gas field nearby vacuum nozzle. Seed motion differential equation was derived using central difference method and then the typical suction trajectory was received which could be described as: seed moved on the horizontal plate firstly under the suction of axial force, then, the radial suction force increased quickly with the rotation of vacuum cylinder, seed could be sucked up from the plate and slipped towards the vacuum nozzle. Suction ability of seeder can be enhanced with the increasing of differential vacuum pressure and be decreased with the increasing of cylinder rotational speed. Rape seeds were selected as experimental materials and experiments were carried out on precision seeder test-rig. Experimental results indicate that the maximal qualified index of more than 95% is received with the cylinder rotational speed and the differential vacuum pressure of 15 r/min and 3～4 kPa. The study provides a basis for the structural adjustment and working parameter optimization of the seeder.