GB830836A - 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

830,836. Coating webs. BRITISH COTTON INDUSTRY RESEARCH ASSOCIATION. April 23, 1958 [April 25, 1957], No. 13157/57. Class 140. A method of applying to a continuously moving sheet of material 15, e.g. of paper, a prescribed amount per unit length of a substance 17, e.g. adhesive, in which the adhesive is supplied to a reservoir 16 from which it is applied in a liquid composition to the web 15 which is then subjected to the squeezing action of a pair of rollers 11, 12, comprises supplying the adhesive to the reservoir 16 at a rate predetermined by the speed of the web 15 and by the prescribed weight per unit length to be applied, any change in the amount of composition taken from the reservoir 16 which results from a deviation of the rate of application from the prescribed rate being utilized to alter the squeezing effect of the rollers 11, 12 on the web 15. A pump 23 delivers stock liquor at the prescribed rate from a vessel 37 to the reservoir 16 whereby a constant amount of adhesive is normally maintained in a control box 20 which forms part of a circulatory system including a pump 21 and an overflow 17 from the reservoir 16. Any deviation in the rate of pick up of adhesive in the reservoir 16, e.g. due to a change in viscosity, results in more or less adhesive being circulated by the pump 21 and thus more or less adhesive being contained in the box 20 which falls or rises on springs 20a. This movement causes a brush 36 to move out of contact with an insulating helical track 35 on a metalcovered drum 34 and thus close a circuit and energize a reversible motor 30 which acts, through suitable gearing, to raise or lower screwjacks 18 supporting bearings for the axle of the roller 12 and simultaneously to rotate the drum 34 to cause the truck 36 to re-engage the track 35. In a modification, the movement of the box 20 controls a needle valve in an air line and thus the air pressure on a piston carrying the axle of the roller 12 which is thus resiliently mounted, the motor 30 and drum 34 and associated parts being omitted. In this embodiment the web 15 is a textile and the applied liquid is a synthetic resin through a bath of which the web 15 passes under a submerged roller before passing through the rollers 11, 12 which expel excess liquid which returns to the reservoir. Various modifications are mentioned. The liquid composition may be the substance itself (as in the first described embodiment) or a suspension, emulsion or dispersion thereof, and it is stated that a change in the weight of liquid in the reservoir 16 may act to alter the squeezing effect of the rollers 11, 12 directly or indirectly, e.g. through a float-operated mechanism, and, where a box 20 is employed, its control of the rollers 11, 12 may be indirect. Where the roller 12 is resiliently mounted, the loading may be via an hydraulically operated ram, levers and weights, or springs. Where impregnation is desired, the rollers 11, 12 need not be vertically disposed, and one side of the reservoir 16 may be constituted by part at least of one of the rollers. The roller 11 is hard rubber and the roller 12 hard metal.