GB1380069A - Stop motion screening apparatus and method - Google Patents

Abstract

1380069 Vibrating screens ORVILLE SIMPSON CO 9 Dec 1971 57355/71 Heading B2H [Also in Division F2] In a method of sorting particulate material using a screen vibrating at a frequency up to 1600 cycles per minute, the amplitude of the motion is varied over a plurality of cycles from zero to a maximum so that the screen is periodically stationary. This may be achieved by means of a pair of rotating shafts each having an unbalanced weight thereon, one shaft being rotated at a speed which is betweene 1% and 15% greater than that of the other shaft. The speeds may be such that the vibratory force is reduced to zero between 10 and 200 times a minute. In the embodiment shown, the screen box 111 is resiliently supported on a base 112 by rods 128 gripped by split blocks 127 and 129 secured to the box 111 and the base 112 respectively, Fig. 8. The base is supported on the floor by springs 122. The shafts 134 and 133 carrying the unbalanced weights are mounted in bearing blocks 135 rigid with the base 112 and are driven by an electric motor 155 via a belt 156, a pulley 157, a shaft 145, a pulley 144, a timing belt 143 and pulleys 142 and 141. The pulley 142 is larger in diameter than the pulley 141 so that shaft 133 is driven faster than the shaft 134. In another embodiment, Fig. 1 (not shown) the vibrating means is mounted on the screen box which is supported above a floor by beams (27) and (28) and rubber blocks (29) and (30). The shafts may be rotated in the same or opposite directions. Alternatively an electromagnetic vibrating device operating at a constant frequency but at a varying amplitude, may be used.