Patent GB-529092-A (GB)
Title: Improvements in or relating to milling of cereal grain
IPC: B02C9/04
Filed: 1939-04-06
Abstract: 529,092. Milling cereals. MORRIS MILLS, Inc., and MILLER, E. J. April 6, 1939, No. 10771. [Classes 59 and 117] [Also in Group I] A method of milling grain comprises breaking the grain without flattening the germ and gradually reducing the endosperm and germ to flour fineness by a plurality of successive reducing and classifying operations, without separating the germ from the stock, while subjecting the endosperm and associated germ particles to extensive aeration to maintain them cool and to render the germ both pulverizable with the endosperm and also non-rancidifying. The process is illustrated in the Specification by a flow diagram which includes five pairs of break-rolls, one pair of quality rolls, two sizing rolls, two pairs of coarse middling rolls and six pairs of fine middling rolls together with associated sifting, screening &c. devices. The break rolls are corrugated and the two rolls of each pair rotate at a differential speed of 2.5-1, the other rolls being smooth and rotate at a differential speed of 1-5-1. Each stage of the process is accompanied by an aeration and conditioning of the germ so that it will be taken off with the endosperm flour. The continuous aeration prevents it from being pressed out flat and either separated as a tailing or. carried off by air to the dust collector. It is rendered pulverizable and is taken through with the endosperm, being gradually and simultaneously reduced in its entirety to the same finely divided state. Since the germ is aerated following each reduction in size, none of it passes off with the flour without having been thoroughly conditioned so as to be rendered non-rancidifying. In the system five products are obtained (1) first grade flour (containing wheat germ) (2) second grade flour (containing wheat germ) (3) dust collector stock (4) bran and (5) shorts. The dust collector stock may be blended with the second grade flour in the operation of the system. Fig. 1 shows a set of twelve purifier units (for sifting, aerating, and removing impurities) combined in one casing and fed with crushed grain from roll unit 150. Each vibrating tray 16, 17 &c. is mounted on swing links 44 and comprises two units formed by a floor 20, Fig. 2, central partition 25 and side walls 21 vibrated by eccentrics 137 and rods 128 resiliently connected to the tray by springs 129. A screen 29 is spaced from the floor 20 and air is drawn through the screen through slots 30 in the walls 20 covered by an inwardly opening flap 33. The sides 21 of the tray are sealed against the sides of the casing by canvas strips 36 and external air is drawn through the casing walls 11 through slots 37 which register with the slots 30. The vibrating trays are sealed against the entry of air except through slots 30 by means of leather connections and the air is aspirated through the screen by a partial vacuum produced in overhead chambers 76, 77 connected to suction pipes 101, 111. Each chamber is of rectangular cross section and terminates above the transverse line of screen 29. Four such chambers on each side of the centre are connected to a transverse manifold 80, 84 con-. nected to the suction pipes 101, 111. Each chamber is perforated at 78 and the manifolds are perforated at 81 the holes being masked or unmasked by a perforated strip which is moved to vary the suction effect. Strips of leather 59, 74 across the screen 29 divide it into three parts forming a head aspiration zone 60 communicating with manifold 84, a central aspiration zone communicating through holes 78, 79 with chambers 76, 77 and a tail aspiration zone 75 communicating with manifold 80. The material passing over the screen 29 lifts a leather flap 56 and falls down a duct 51 on to a reversely. inclined tray oscillated by rods 136. The suction chambers for this tray are formed on the bottom 20, of the top tray and the manifolds 86, 88 are connected to the suction pipes 101, 111 by a branch pipe 104 entering an elongated slot in the manifold. The second tray is sealed by leather strips to form three aspiration zones similarly to the first tray and the succeeding trays are similar. The stock on the screen at the head and tail aspiration zones is subjected to a continuous or steady current of air but the stock on the central zone is subjected to a rapidly pulsating current of air, there being one pulsation per cycle of screen vibration and being in synchronism therewith. The air pulsations arise from the oppositely vibrating movement of the trays and the action of the flaps 33 over the air inlet holes 30. The roll unit 150 has a casing 151 having side walls spaced from the rollers 153 for the passage of air and having a side door 154 provided with screened holes for the passage of air into the casing below the rolls so that the rolls are cooled and the stock aerated before, during, and immediately after passing through the rolls.