A Basic Study on Harvesting of Standing Grain

Abstract

We attended to the Japanese ancient method of stripping of rice grain (SEMBAKOKI), and devised the new method of stripping. The outline of this method is shown in Figs. 1 and 2. Experiment was carried out with the model conformed to the devised stripping method. It was made so as to simulate to strip standing rice plant in the field. This method seemed to have merits that standing harvesting would be possible and that the harvester could be small in size and requires less power. Theresults and discussions were as follows;
1) The peripheral speed and the slit width of stripping tooth were the main factar that had effects upon the condition of stripped grain. As peripheral speed increased, the number of branch-and ear-breaking increased. When slit width was 4mm that was larger than the width of grain, the num ber of branch-breaking was small but the number of unstripped grains was great. When slit width was 2mm that was smaller than the width of grain, the latter was small but the former, great. At the case of 2mm, the number of branch-breaking was larger than at the cases of 3 or 4mm. There was no significant difference in pedicel-breaking between the cases of 2mm and of 3 or 4mm.
2) From this experiment, we found, that whenn chucked rice plant stood, the peripheral speed should have to be taken less than 200cm/ sec, and when rice plant was hung, less than 400cm/sec. To prevent branch-breaking, the stripping apparatus should be laid out so that rice head would be stripped first with the teeth with slit width of 3 to 4mm, and then with the teeth with slit width of 2mm.
3) We determined two probabilities; one for a culm held by a slit and the other n culms held. by a slit. The relations between these two probabilities and the centre distance of teeth gave the optimal value from 10 to 15mm for the centre distance. Fig. 6 gives the head angle.