GB500816A - Improvements in and relating to screening apparatus - Google Patents

Abstract

500,816. Sifting-apparatus. WILLIS, T, and WADDLE PATENT FAN & ENGINEERING CO., Ltd. April 14, 1938, No. 28449/37. [Class 117] Screening-apparatus comprising one or more screens is characterized in that the screens are inclined and slidably reciprocate un horizontal guides, and means are provided for suddenly arresting the movement when the lower end of the screen is leading In the arrangement shown in Fig. 1, two sets of screens 5, 6 are inclined in opposite directions and are mounted in troughs supported by rollers 44 on horizontal guides. The screens 10, 11 in the upper trough are of graded mesh, the ovensize materials being delivered to shoots 13, 14 repectively. The member 9 acts as u haffle. The material passing through the screen11 is collected hy the base 8 and passes by way of the opening 18 and deflector 17 into the second trough which may contain one or more superposed screens 19 and a collecting plate 21 leading to suitable receptacles or conveyers. The driving arrangements for the screens consists of a shaft 24 carrying double-lobed cams 25 with radial steps 26 engaging lugs 27 carried by the screening troughs. Tension springs 29 adjustable as to tension and direction of pull, hold the abutments against the cam faces. Abutments 31, 32 on the screen frames engage adjustable fixed abutments 33, 34, to produce a shock when the spring tension is released by the rotation of the cams. The stop adjustment is provided by interposed wedges 35. In a modification, Fig. 2 (not shown), the rotary cams are replaced by endless chains carrying wedge-shaped members co-acting with abutments on the screens. The screen arrangement comprises three sets of screens, the upper two sets serving to screen out the larger sizes and deliver the fines to the lowest set which has a number of .superposed fine screens of graded mesh. The screens may be mounted on inclined links and actuated against gravity by the cams. An alternative construction is shown in Fig. 3, in which the movement of the screens is obtained by an eccentric 62 and connecting rod 61 made in two telescoping parts with an interposed cushioning spring. An abutment 64 on the screen is brought against a fixed stop 63 within the limits of the throw of the eccentric the excess movement of which is taken up by the interposed spring.