Peanut is both an important oil crop and high quality protein resource, its planting area is about 4.7 million hectares all the year round, which is distributed widely in China. The classifying of pods is not only an essential key link to post-harvest processing, but also the most important and basic link to improve the added value of peanut and its related products.Due to irregular size of pods and classification difficulty, currently, lack of economical mechanized classifying equipment only for peanut on the market, what existed are just large or small dual-purposed classifying equipments for peanut pods with undesirable effects. Cylinder grading is a more suitable method for the classification of pods at the moment, but still there are series of problems existed such as low operating efficiency, poor smoothness and low qualified rate of grading, etc, so the equipments couldn’t fully meet the needs of peanut pods grading. Therefore, in this paper, firstly, physical characteristics of peanut pod including 1000-grain weight, dimension, sliding friction coefficient and so on were measured, then combined with existing cylinder grading equipments, improving the grading quality of peanut pods by optimizing the structure and working parameters of cylinder screen. The details are as follows:Firstly, the 1000-grain weight, dimension and sliding friction coefficient of tested specimens should be counted, which provide basic data and theoretical basis for the subsequent test-bed optimization and experimental design. Combined with existing cylinder grading technology and optimizing screen cylinder, the size and position arrangement of classifying screen apertures were redesigned, peanut screening situation was simulated through DEM, analyzing the granular distribution of peanut pods in the grading process and the effects of pod axial velocity caused by different screen cylinder speed and the pitch of guidance spiral were analyzed as well.Test-bed of peanut pod cylinder screening was constructed, feed rate was controlled by selecting bucket elevator combined with oscillating feeder, screen cylinder speed was controlled by using frequency converter, peanut axial velocity was controlled by switching guidance spiral with different pitches as well. White sand and 4 red granular peanut were utilized as experimental materials, qualified rate of grading as main control index, orthogonal test was conducted, change rules of grading index affected by feed rate, screen cylinder speed and pitch of guidance spiral were analyzed. To further enhance qualified rate of grading pods, orthogonal combination method of quadratic regression was adopted to design the peanut pods grading test, getting the functions of feed rate, pitch of guidance spiral, linear velocity with qualified rate of grading pods through analyzing the results of test, which provides theoretical basis for structural design of peanut pods grading equipments and selection of working parameters.We could obtain the function of qualified rate of white sand grading and these three tested factors by using 3 factorial orthogonal combination test of quadratic regression, the function was solved to predict optimal scheme. Finally optimal parameter combination was obtained: feed rate was 738kg/h, pitch of guidance spiral was 167 mm and velocity of screen cylinder was 33r/min, qualified rate of grading white sand peanut pods was obtained as high as 93% by feeding into regression equation. Because of the regular shape of 4 red granular peanut, the qualified rate of grading could reach more than 80%, the highest rate reached 93% when feed rate was 800kg/h, pitch of guidance spiral was 110 mm and velocity of sieve cylinder was 33r/min, the optimal parameter combinations for these two varieties of peanuts were tested, respectively, verification results were consistent with analysis, grading tests of two varieties had reached the optimized and improved expectations. |