Abstract:In order to achieve the function of uniformly punching holes in the film for smallgrain crops such as rapeseed, a film hole forming device with a flangetype roller and screwtype conical nail was designed to solve the problems existed in traditional holeforming seeding device like large and complicated structure, adhering soil and seeds, and film damage. The ranges of main structural parameters were determined. The kinematics model of film hole forming device was built. The trajectories of key points of conical nail were analyzed. The punching process on film was determined and the film hole size was analyzed based on the trajectory equation. The fourfactor and threelevel virtual orthogonal experimental study of structural and working parameters of film hole forming device were carried out with the aid of ADAMS. The apex angle of conical nails, the diameter of conical nails, the radius of wheel, and the working speed were used as experimental factors. The film hole length and the distance deviation between two membrane holes were used as experimental evaluation. The simulation experimental results showed that the order of factors affecting the film hole length was the radius of wheel, the apex angle of conical nails, the diameter of conical nails, and the working speed. The order of factors affecting the distance deviation between two membrane holes was the radius of wheel, working speed, apex angle of conical nails, and diameter of conical nails. A better parameter combination was obtained: the apex angle of conical nails was 53°, the diameter of conical nails was 16mm, the radius of wheel was 65mm, and the working speed was 4km/h. The field experiments were carried out with the optimal parameter combination. The results showed that the shape of most of film holes was regular and generally roundlike. The length of film holes was more than 18mm, which was consistent with the simulation results. The coefficient of variation of film hole length in each row was 4.98% and the variation coefficient of uniformity of film hole spacing in each row was 3.44%. The experimental results showed that the combination of experimental parameters was reasonable. The film hole forming device satisfied the design requirements.
