Study on machine-crop parameters of cylinder threshers for cumin threshing
Prior to developing a cumin thresher, the efficiency factors of cumin threshing was investigated. The effect of thresher variables including the moisture content, cylinder type and cylinder speed, feed rate and concave clearance on weight percentage of separated seeds, shattered stems and damaged seeds were studied in this research. The results showed that as moisture content increased from 7% to 13%, separated seed and damaged seed decreased from 92.8% to 90.4% and from 10.1% to 7.6%, respectively. However, increasing cylinder speed from 12.8 to 16.5 m/s, increased the percentage of separated seed, shattered stems and damaged seed. The cylinder type did not have significant effect on weight percentage of separated seed, while it had a significant effect on shattered stems and damaged seeds. It was concluded that the rub bar cylinder was better than the rasp bar cylinder. Thus, the rub bar cylinder, 16.5 m/s cylinder speed and 7% grain moisture content were the most suitable conditions for cumin threshing.
Keywords: thresher, cumin, moisture content, cylinder type, cylinder speed, feed rate, concave clearance