The Design and Development Of a Chick Pea Second Sieving and Grading Machine

Abstract

Sieving and grading are two final operations of high quality grainproduction. Farmers in Iran normally winnow peas by hand, which leaves a largeamount of debris among the peas. To correct this problem, a machine wasdesigned and developed at Tehran University to second sieve and gradechickpeas. A low price, easy maintenance and usage, and technologyappropriate for Iranian farmers were important considerations in the developmentof the machine. The following steps were taken during the design of the machine:Physical properties, terminal velocity, and coefficient of friction of five differentvarieties of Iranian chickpea:Jam, Philip, Bivanij, ILC-482 and ILC-12-60-31--were determined. The following parameters and factors effecting machineoperation were determined: sieve, number of sieves, shape and size of opening,sieve angle, oscillation stroke, angular velocity, volume of air entered, size andshape of air channel and fan size. The machine was built and evaluated. In thedesign and construction period, the variability, changeability, and adjustability ofthe whole system was observed. The sieve slope, sieve type, angular velocity,and air velocity of the machine can be altered, making it suitable for other cerealcrops. The machine was evaluated with a flowing of known weight (2 kg), mixed, hand-cleaned peas (debris free) with 15 grams of known weight chaff and stemand 100 grams of clods and stones to determine its cleaning and grading ability,as well as overall efficiency. The arithmetic mean diameter was 6.7-9.7 mm withan average of 7.8 mm. The terminal velocity of a whole chickpea was 10-15 m/s,with an average of 12.6 m/s. For the dried leaves and stems, the averages were3.0 m/s and 5.5 m/s, respectively. The minimum coefficient of friction occurred ongalvanized steel with a 0.28 radian and the maximum coefficient of frictionoccurred on fiberglass with a 0.33 radian. The machine is capable of gradingpeas into four different classes: industrial use, human consumption, animal feed,and cultivation seed. The cleaning efficiency of the whole chickpea was 93 %and the debris was 94 %. Overall, machine efficiency was 84 %.