Design and test on pneumatic type automatic tray feeder of seeder for tray nursing seedings of rice

Abstract: Factory seedling nursery is one of the most important parts in the process of rice production mechanization. At present most of the work feeding the trays into the rice seedling nursery planter is finished one by one manually, which is labor-intensive and inefficient. In order to reduce labor intensity and improve the production efficiency of rice seedling nursery pipeline, a pneumatic type automatic tray feeder, which could supply the seedling trays rapidly and automatically, was developed after studying the characteristics of frequently-used tray. The device consisted of conveying mechanism, tray dropping mechanism and control system. The conveying mechanism, which included the former conveying section and the latter conveying section, was designed to convey the trays that were stacked before use (which could be up to 10 trays per stack). By establishing the mathematical model of convey mechanism and analyzing the conveying deceleration process of trays, the conveying speed relationship between the pneumatic type automatic tray feeder and the rice seedling nursery pipeline was obtained, so that the speed of the automatic tray feeder could be confirmed and meet the requirements of tray conveying under the different productivities. The tray dropping mechanism was designed to feed the trays automatically. By the cylinder driving, the trays except the bottom tray could be rapidly lifted through the lifting finger rotation on either side of the trays. After the bottom tray was conveyed away, the lifting finger rotated in the opposite direction and the trays would be dropped, and then that cycle was repeated. The control system was designed so that the conveying mechanism could be controlled to convey trays orderly and the tray dropping mechanism could be controlled to feed trays accurately. Through the proximity switches detecting of the control system, the stacking trays would be conveyed into the latter conveying section and the trays would be lifted or dropped by the tray dropping mechanism. Therefore, the trays could be automatically supplied one by one rapidly. In order to test the performance of the pneumatic type automatic tray feeder, the orthogonal experiment was carried out, in which the feeding success rate was regarded as the index and the productivity, the feeding time of tray dropping mechanism and the stacking trays deviation were regarded as the influence factors. Experiment results showed that the sequence of influence factors in affecting the feeding success rate from high to low was the stacking trays deviation, the feeding time and the productivity. The stacking trays deviation had significant influence on the feeding success rate while the feeding time had certain influence on it. The feeding success rate decreased with the rising of the stacking trays deviation and the feeding success rate increased with the rising of the feeding time. The productivity had little effect on the feeding success rate. When the stacking trays deviation was 0-6 mm and the feeding time was 0.8 s, the feeding success rate was 98.67%-100% with a productivity of 600-1000 trays per hour. The pneumatic type automatic tray feeder can effectively enhance the productivity of rice nursing seedlings pipeline and reduce the labor intensity. The experimental indices meet the using requirements of rice precision seedling. This study has a great significance in improving the automation level of rice nursing seedlings pipeline.