GB817838A - Method and means for the automatic regulation of the continuous application of specified amounts of solids or liquids to a moving sheet of material - Google Patents

Abstract

817,838. Coating webs. BRITISH COTTON INDUSTRY RESEARCH ASSOCIATION. June 19, 1957 [June 22, 1956], No. 19325/56. Class 140. A prescribed weight per unit length of a substance, e.g. starch, is applied to a continuously-moving sheet of material, e.g. a warp, under controlled conditions by continuously metering to a container one or more solid ingredients constituting or comprising said substance at a rate predetermined by the speed of travel of the sheet material and the prescribed weight of substance per unit length to be applied thereto, continuously treating the material in the container to give a dispersion, solution, emulsion, melt or other liquid form, continuously applying this to the sheet material from the said container, or from a reservoir to which it is continuously supplied at a similarly predetermined rate from the container, and using any change in weight of the contents of the container or reservoir, which results from a deviation from the prescribed rate of application of the substance, to alter some property of the liquid so as to correct said deviation. The changes in weight of the container or reservoir may be detected by direct measurement of weight or by indirect measurement from change of volume, depth or pressure. The property of the liquid which is altered may be the concentration, effected by altering the amount of diluent in the liquid, but the viscosity may alternatively be altered. A mixture of the solid ingredients may be metered or, if more than one solid is present, each may be metered or dispensed individually. As shown (Fig. 1) an endless conveyer 12 carries starch from a vessel 11 to a hopper 13 which has internal agitation means 14. In the hopper an automatic weighing mechanism 15 delivers discrete quantities of starch through a pipe 16 to a container 17. The mechanism 15 is operated, at a rate determined by the rate of travel of the sheet material, through a control switch 28 actuated through adjustable gearing 29, 30, from which the rollers 26 progressing the sheet 27 to be coated are also driven at predetermined speed. The container 17 has a central vertical partition 17a, on each side of which are agitators 18, and an overflow pipe 22 leading to a shallow reservoir 23 provided with a partition 24. Water is supplied to the container 17 at a predetermined rate by a pump 37 driven from the gearing 30, and also through a branch pipe 31 controlled by a magnetic valve 35. On one side of partition 24 is provided a steam heating tube 25, which gelatinizes the starch suspension in that side of the reservoir, and on the other side is the roller system 26 for coating the sheet 27. A pipe leads from the bottom of the reservoir 23 to a float chamber 32 and is covered by a relaxed diaphragm 33; any variation in the head of liquid in the reservoir is thus transmitted to a float 34 and a float switch 34a which adjusts the magnetic valve 35 and varies the supply of water to the container 17 to correct the level. Tallow may be admitted to reservoir 23 through a pipe 39 and a gear pump 40 also driven from the gearing 30. In another embodiment reservoir 23 may be supported on a spring so that its movement when the weight of liquid changes alters the rate of the water supply. In another embodiment a hopper filled with solid coating substance is supported by one arm of balance, the other arm of which carries an adjustable balance weight and also a suspended chain. The other end of the chain is wound up on a drum at a predetermined rate by mechanism connected to the gearing 30. As the chain is wound up the hopper falls closing a circuit which operates a delivery device for the solid material, the circuit then being broken by decrease in weight of the hopper, and the cycle repeated. In another form the hopper is balanced by a tank from which water or other liquid is metered at a prescribed rate, the water, when used, being afterwards supplied to mix with the water in the container. Other means of delivering controlled amounts of solid may be (1) an endless conveyer supported on a pivot and counterbalanced, a hopper being arranged to discharge solid on to the conveyer when it is out of balance; (2) a speed-controlled bucket type conveyer discharging directly into the container. Specifications 654,178 and 792,663 are referred to.