عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Although the mean of combine losses is about 4-5% in advanced countries, unfortunately in Iran is about 20% and higher. In order to obtain little loss it is necessary that product processes such as cutting, transporting, threshing, separation, etc. would be optimized. Expressing the equation of different parts of harvesting is the first step. Threshing is one of these processes which has more effect on combine performance. Reduction of MOG passing from concave could reduce the load on shoes that would increase cleaning system efficiency and decrease foreign materials in bin. Cutting height, feed rate, threshing clearance rate and cylinder speed are parameters which were used in combine design and its performance evaluating too. In order to evaluating of these parameters effect on threshing performance, experiment was conducted in 4×3×3 factorial pattern with Randomized Blocks design. Independent variables in this experiment were cutting height, feed rate, threshing clearance ratio and rotational velocity of threshing cylinder. MOG passing from concave was considered as dependent variable. Results showed that the effects of treatments on dependent variable were significant but interaction effects of them were not significant (P<0.01). As cutting height, feed rate and threshing clearance decreased, MOG passing increased. Also it (dependent parameter) was proportional with cylinder speed. Multiple regression was used to express relation between dependent and independent parameters. The most compatible model for MOG passing (y3) was as follows: y3 =exp(c1x1+ c2x2+ c3x3+ c4x4) Which x1, x2, x3 and x4 were cutting height, feed rate, threshing clearance rate and speed of threshing cylinder respectively and c0, c1, c2, c3 and c4 were constants.