Design and development of a vertical plate precision seed metering device with positive seed knockout mechanism

Abstract

Planting of seeds according to agronomical requirements is one of the most important and critical farm operations for crop cultivation. Placing of seeds at proper location is required to maintain plant to plant spacing in a row. A vertical plate precision seed metering device was designed and developed for field pea. Cells with three different depths of 8.48, 8.85 and 9.22 mm and three shapes of 20^o, 30^o and 40^o left side angles were designed to obtain nine different plates. A seed metering device with different plates was fabricated and mounted on experimental setup. Performance of the metering device was evaluated under laboratory condition at three speeds of 37.04, 44.45 and 51.86 rpm. The results showed occurrence of stuck up seeds in the cells and higher missing hills which may be due to non-release of seeds from the seed metering device. In order to seed release from the metring device, a mechanism for positive seed knockout was designed and was incorporated in the developed metering device of different sizes and shapes of vertical plates. The performance of vertical plate precision seed metering device with positive seed knockout mechanism was also evaluated under laboratory conditions. The results showed that cell of 8.48 mm depth and 40^o left side angle on a vertical plate seed metering device with positive seed knockout mechanism performed better with lowest average missing index of 2.67%, 0.5% multiple index and highest uniformity of seed placement of 96.83%. Stuck up of seeds in the cells of the seed metering device was not observed after incorporating positive seed knockout mechanism.