Automatic size fraction screening device and method

The invention discloses an automatic size fraction screening device. The automatic size fraction screening device comprises two fence boards fixedly arranged on an electronic scale. A plurality of sieves and supporting plates are detachably connected between the two fence boards, and sieve holes of the sieves are sequentially reduced from top to bottom; the front end and the tail end of one side of each sieve are connected with vibration devices; the multiple vibration devices control the vibration frequency through an electronic processing system so as to sequentially screen materials on thesieves from top to bottom, and the multiple vibration devices are all electrically connected with the electronic processing system. The electronic scale records the initial weights of the fence boardsand the multiple sieves before vibration and the total weight of the multiple sieves and the materials on the sieves after vibration through the electronic processing system and calculates the percentage of the materials of a