GB427355A - Improvements in or relating to the manufacture of sheet glass - Google Patents

Abstract

427,355. Glass manufacture. STEVENS, A. H., 5, Quality Court, Chancery Lane, London.-(Byrnes, C. P. ; Sewickley, Pennsylvania, U.S.A.) Feb. 10, 1934, No. 4505. [Class 56] A method of making sheet glass consists in drawing a sheet upwards from a bath of molten glass through an enclosed, partly enclosed, or shielded atmosphere until the surface of the glass has set sufficiently to prevent marring by contact with a solid, and then drawing the sheet over a cooler guiding surface in the enclosed space, the draw being continued at an angle to the plane of the part of the sheet below the guiding surface. The sheet s. Fig. 1, is drawn from a forehearth 2 into a chamber 5 formed by a pair of transverse arches 3, 4 which dip into the molten glass. The lower edges of the arches are curved and are submerged to a greater extent at their middle portions than at their ends in order to equalize the temperature of the glass across the whole of the width from which the sheet a is drawn. The drawing chamber 5 contains coolers 11, and guiding- members 18, 19 which prevent the meniscus c of the sheet from moving about. The guides are arranged at such a distance above the surface of the molten glass that the sheet becomes set before it makes contact with the guides. Preferably, the guides consist of rollers which are kept at a dull red heat by circulating air through them. They are rotated either in the same or in opposite direction to the movement of the sheet s, but in any case, they move at a different speed from that of the sheet so that they exert a wiping action on the glass. The temperature of the glass in the forehearth is so controlled that the sheet remains in contact with one of the guides preferably the roller 18. The meniscus tends to approach the outer arch 4, and the parts of the sheet s above and below the roller 18 are not in the same plane. The sheet s after leaving the guides, is drawn through a leer 21 of the Fourcault type by rollers 20. In a modified construction, the roller 19 is arranged at a higher level than the roller 18 and at such a distance apart that the sheet makes contact with both rollers. In this case, the sheet is deflected slightly as it passes the rollers. In all cases, watercooled pipes 22, 23 are arranged above the rollers and near to the sheet in order to complete the setting of the glass. Each cooler 11 consists preferably of an elongated box along the upper part of which a pipe 27, Fig. 6, extends. Water enters the pipe 27 and escapes through perforations, the inner end of the pipe being plugged. The water is distributed along the length of the box and is drawn off through an outlet pipe 28.