Verfahren und Vorrichtung zur Massenherstellung mit glasartigen UEberzuegen versehener Glasscheiben

摘要

Glass sheets, e.g. spandrel units, are coated by conveying a plurality of flat glass sheets horizontally with their undersurfaces in direct contact with conveying elements while sequentially applying, e.g. by spraying, a liquid dispersion of a finely-divided coating material to the upper surfaces thereof, gradually heating the coated sheets to an elevated temperature sufficient to anneal the glass sheets throughout their thickness, to volatilize the liquid and fuse the coating to the surface, but insufficient to cause the sheets to soften, for a comparatively brief interval and cooling the sheets rapidly to impart a temper thereto. Any coating material which inadventently contacts the bottom surface of the glass sheets may be removed before exposing the coated sheets to the elevated temperature. The liquid dispersion may be of a finely-divided ceramic enamel which may also contain a finely-divided metal powder, e.g. aluminium. Alternatively, a liquid dispersion of metallic powder may be applied to glass sheets covered with a liquid dispersion of enamel which may be a clear composition. The coating composition may be a suspension in water or alcohol, e.g. methyl, butyl, n-propyl carbinol, glycerol and glycol, and may contain sodium nitrite, sodium pyrophosphate, silicones, octyl alcohol, citric acid and methyl cellulose. Aluminizing compositions specified contain oxides of lead, silicon, boron, zirconium, sodium and cadmium, and colouring pigments, e.g. cadmium sulphide and sulphoselenide, chromium oxide, titanium oxide, ferric oxide, and cobalt oxide. In the apparatus described, glass sheets are conveyed by rolls 92 and urged into washer section 14 by last roll 94 and pinch roll 96. The sheets, conveyed on rolls 103 which co-operate with wringer rolls 104, are washed by brushes 106 supplied with detergent from apertured pipes 105, the sheets then being washed with, for example, water, from spray nozzles 109 prior to further washing by brushes 112. The sheets are dried by dry air blown in through nozzles 115 prior to passage on cable conveyer 16 into spray booths 20, 22, where the sheets are coated by spray guns. Any coating material inadvertently applied to the under-surface of the sheets is removed by brushes 180 prior to the entry of the sheets into furnace 28. Heat-resistant conveyer rolls 46 carry the sheets through the furnace which contains heaters 204, 206 controlled by elements 208, 210. The temperature is increased rapidly in zone 30 of last furnace section 29 by additional heaters 212. The sheets are then cooled in section 32 by air from nozzles 254, the first of which may be extended to extremity 256. Castor tables for placement of displacement of the sheets at various points in the process without interruption of the process are described.