GB954934A - Method and apparatus for performing a change in the direction of movement of a travelling paper web - Google Patents

Abstract

954,934. Paper; paper-making. PAPPERSBRUKENS SERVICEAKTIEBOLAG. Oct. 16, 1961 [Oct. 17,1960], No. 36976/61. Addition to 909,501. Headings D2A and D2B. In changing the direction of movement of a travelling paper web, to increase its softness, flexibility and stretchability, the web is transferred from a conveying surface 11, Figs. 1 and 2, on to another conveying surface 13 at a location 17 in the nip 15 between the conveying surfaces, where they move in substantially opposite directions with the same or slightly different speeds and are spaced apart by a distance of the order of twice the thickness of the paper web, which is thus folded, i.e. turned substantially back on itself, along a fold line at the location 17. The conveying surfaces may be moved relatively to each other to vary the pressure at the nip. A steel blade may be inserted, or jets of air may be directed between the faces 19 and 21 of the paper web inside the fold. These faces are, preferably, brought into sliding contact, Fig. 2. A lubricant, such as powdered talc, may be fed into the fold, as by being applied, before folding occurs, to the face of the paper which does not touch a conveying surface. The lubricant may be retained in the fold by the said jets of air or by rotating brushes. An adhesion-improving substance, such as powdered rosin or resin or water in the form of spray or condensate from a surrounding atmosphere of steam, may be introduced between the paper web and one or both conveying surfaces, which may be heated. The paper web may be held in contact with one or both conveying surfaces by charges of static electricity generated frictionally on the paper web by allowing it to slide over a braked rubber roller, or by keeping the pressure of the atmosphere on the contacting face of the paper web lower than the pressure on its other face, as by applying suction. The paper web may be subjected to a plurality of changes of direction by bringing alternate faces of the web into engagement with, and transferring the web between, pairs of conveying surfaces. The resulting fold lines may be inclined at different angles to the edges of the web. The conveying surfaces may be pairs of cylindrical rollers, e.g. provided with inter-meshing rectangular teeth, or pairs of endless bands or parts of a single endless band or crossing sets of parallel threads or bands. Alternatively, one conveying surface may be a roller and the other an endless band. The paper web may be carried on an endless band into the nip between two rollers. One conveying surface may be a drying cylinder, e.g. a Yankee cylinder, of a paper-making machine. The conveying surfaces may be rigid, elastic or resilient, perforated, e.g. porous or foraminous, or unperforated.