Patent GB-707463-A (GB)
Title: Improvements in or relating to a method of and apparatus for weighing or controllingflowable solid materials
IPC: G01G11/00
Filed: 1951-06-04
Abstract: 707,463. Weighing-apparatus. PILLSBURY MILLS, Inc. June 4, 1951 [June 6, 1950], No. 1317751. Class 143 [Also in Groups XX and XXXV] In the continuous weighing of flowable solid material the material is continuously conveyed through a conduit constructed as a balance weighbeam having two sections along which the material is successively conveyed in opposite directions and an inlet 40 and outlet 41 arranged coaxially to each other on a line intersecting the fulcrum axis of the beam so that the charge and discharge of material does not affect the balance. The balance beam may comprise two tubes 11, 12 connected by side plates 13 with vertical inlet 40 and outlet 41, and the tubes being cut away at their far ends and joined by end plates 15, 18. Angle-strip 20 connected to the side plates has depending wedge-shaped fulcra 25 which engage in fulcrum blocks mounted on supporting upright 29, and a bracket extension of the angle section 20 mounts the drive motor and gearbox for screw conveyers in the tubes 11, 12, and an adjustable sliding counterweight 38, so that the beam is counterbalanced. The free end of the beam may be provided with an arcuate member 45 coacting with a permanent or energized magnet 48 and acting as an eddy current brake, or gyroscopic damping may be employed. The balance beam pivot may comprise steel drums between the wedge fulcrum members 25 and the side plates 13, coacting with adjustable permanent magnets mounted close above them on the supports 29 to reduce pivot friction, and ball bearings in place of knife-edge fulcra may be used. In a modification, the screw conveyers are coaxial and the outer is rotatably mounted by ball bearings on an inner fixed tube housing the inner screw. The latter drives the outer screw through gearing carried by a closure cap at the far end of the beam. In a further modification, the beam casing comprises two endless belt conveyers driven from outside the casing by sprockets. Spring-mounted rubber wipers keep the surfaces of the conveyers clean. In all modifications, the free end of the beam may comprise a contact finger 182, Fig. 10, which, depending on whether the beam contents are under or over weight, contacts an upper or a lower switch member to thereby increase or decrease the feed of material to the conduit controlled by a vibrating screen 180. Alternatively, load variations on the beam may be metered, and/or retroactively controlled to a constant value by an electric resistance, or hydraulic or pneumatic detectors sensitive to pressure variations on it from the beam. Simultaneously the amount of added constituent to a material, e.g. tempering water to grain or powdered vitamins to flour, may be controlled by a further unit action proportionately and in parallel with the feed control unit 180. Two similar balance units in series, Fig. 10, may be used for measuring the moisture content of flour or of the solvent residue in oil seed meal, such as ground soya beans, after processing with the solvent to remove the oil. The first balance unit 173 produces a constant flow of material and of moisture or solvent to the second unit 189, and the latter is electrically or otherwise heated as by infra-red radiation to remove the moisture or solvent content, its unbalance indicating on a scale 185 and recording at 186 the moisture or solvent content. In a further modification, the conduit comprises a middle section extending on both sides of the fulcrum and two half-section on opposite sides of the rulcrum. that half of the continuous conduit on one side of the fulcrum is electricany heated to evaporate moisture, solvent or vaporizable solid, tne unbalance indicated and recorded on instruments denoting me moisture &c. content, tne arrangement tnus being a differential balance. In a still further modification, Fig. 12 (not shown), two separate streams of material are fed to two separate conduits each in two connected portions extending symmetrically outwards and inwards as beam arms from tne rulcrum and to separate inlets and outlets. If wneat and tne flour extracted from it are passed to the two inlets tne differential weight deflects the beam and so measures the percentage of extraction. All tne above apparatus may be laboratory units or large-scale production control and processing units.