GB881217A - Sifting apparatus - Google Patents

Abstract

881,217. Sifting apparatus. GENERAL MILLS Inc. May 28, 1959 [May 29, 1958; March 10, 1959], No. 18189/59. Class 117 A sifter box 10, supported on hangers 40, 42, and reciprocated by a driven eccentric 48 and rod 46 houses screen 24 which divides the box into upper and lower substantially closed chambers 26 and 28, and transverse partitions 68 and 70 located adjacent the feed inlet 30 and outlets 36 and 38 equalise the air pressures above and below the screening surface during reciprocation, and thereby provide an improved flow of stock over the screen. The latter extends longitudinally between imperforate plates 32, 34, and each partition includes a vertically adjustable plate 74 held in position by wing nuts 84. The lower edges of the plates are so located as to allow stock to pass but allows little air to flow from the upper chamber. A further partition 112 may be provided, and the plates 74 may be L-shaped. The sifter box 120 of Figs. 4 and 5 is divided by the screen 160 into upper and lower chambers 162 ,164, and longitudinally extending partitions 204 perforated at 211 and spaced from the sides of the box provide an equalisation of the air pressures above and below the screen during reciprocation. The partitions are secured to the removable top wall 124 of the box and, as shown, the stock supplied through inlet 166 flows along the screen between those partitions thus leaving free the side parts 214 of the screen to allow air communication between the upper and lower chambers as indicated by the arrows. Longitudinally extending pairs of screen support plates 184, 198, also perforated therealong at 216 are provided. In a further modifications the entire width of the screening surface is used for classifying the stock, and perforated longitudinal partitions extend along the sides of the screening surface and are spaced from the side walls of the sifter box and provide air communication between the upper and lower chambers of the sifter box. A number of such sifter units may be superimposed with intermediate imperforate conveying pans, thereby providing pneumatically separate sifting chambers within a single sifter box. Reference has been directed by the Comptroller to Specification 837,037.