عنوان مقاله [English]
The most important part of the agricultural products sizing machines, is sizing unit. The main purpose of this research was to determination some engineering properties of almond kernel and design and manufacturing of sizing unit for use in a sizing machine. To choose the best sizing mechanism, the concept of visual sizing parameter function was used. The results showed that the thickness and length dimensions, with coefficients of 0.647 and 0.353 respectively, play the most important role in the sizing of almond kernels. In addition, statistical studies showed that the thickness dimension, in terms of having the lowest dispersion and standard deviation of data, is also the best dimension to design the device. To determine design parameters, some physical and mechanical properties of three varieties of almond kernel namely Sefid, Sangi and Mamaei, at three moisture levels (3, 9 and 15%), on three surface textures including polished steel, Teflon and wood were evaluated. The results showed that with increasing levels of humidity, the friction coefficient in all three varieties and on all three surface textures, showing an increasing trend while the force needed to break almond kernels showing a decreasing trend. Based on the obtained results, sizing unit using a pair of diverging polished steel rollers, was chosen as the best option and after determination of other attributes such as appropriate length and diameter for rollers, was used in special device for sizing almond kernels.