| 摘要 |
1358061 Abrading glass articles GLAVERBEL 21 May 1971 16285/71 Heading B3D [Also in Divisions B5 and C1] An edge n the edges of a glass article is strengthened by smoothing at least a portion of the surface of the edge by abrasion and then subjecting the edge to a rectifying treatment before and/or after chemical tempering, the rectifying treatment removing or reducing the impairment of the surface by faults liable to cause stress concentrations under tensile loading. The invention is of particular use for glass sheets which are stacked in packing, but glass bowls or laminated panels are also disclosed. Parts not to be treated may be protected, e.g. by a matrix or a steel frame holding the glass or by a liquid film, paraffin wax or a polymer film. The abrasion may be effected in two or more stages using a finer grade of material in the second stage. Abrasive strips of canvas or paper carrying alumina or emery or silicon carbide; grooved wheels surfaced with grains of alumina or silicon carbide or a diamido grinding whele may be used. During abrasion, the glass work may be wetted with mineral oil or water or a mixture thereof in a jet so as to cool the edges. The chemical tempering may be by immersion or by spraying from jets although a gas, a paste or a vapour are also referred to. For soda lime glass, larger ions such as potassium, rubidium or cesium may replace the sodium, or lithium may be used. Examples given are KNO 3 ; CsNO 3 + Cs 2 CO 3 ; LiNO 3 + NaCl for immersion and KNO 3 for spraying. A direct or alternating electric field may be used to promote ion diffusion. Alternatively, diffusion may be promoted by the use of sound or ultrasonic waves. The rectifying treatment may be by use of a fine polishing flame, but only before the chemical tempering or, the preferred method, by etching with a fluorine containing medium. Examples given are HF + H 2 SO 4 ; HF; NH 4 F 2 ; NaF + H 2 SO 4 . Examples are given, using glass in the following ranges in percentages by weight: SiO 2 64- 72; Na 2 O 11-14À2; CaO 6-8À1; MgO 4À5-7; Al 2 O 3 1-6; B 2 O 3 0 or 8. Before or after the chemical step, a coating layer may be provided on the articles, either a hard coating or one with optical properties. |
