| 摘要 |
A method of toughening glass articles comprises exposing a heated glass article to the action of a plurality of annular divergent jets of a gaseous chilling medium and controlling the pressure of gas within the areas surrounded by the jets independently of the pressure within the jets. Preferably the heated article, for example a glass sheet 12, is placed between opposing pairs of annular orifices 8. The orifices are formed by convergent inner cones 5 and outer cones 4 separated by struts thus giving a passage 7 which forms a divergent stream of gas. In order to differentially toughen a heated glass article the aperture 22 within the annular orifice is connected to means 20, 21 for supplying a gaseous chilling fluid at a different pressure from that delivered through the annular orifice; and the aperture 22 may be connected either to a supply of gas at a lower pressure than that supplied through the annular orifice or to an exhaust means so that during the quenching operation control of the differential toughening of the said article is effected. Preferably the exhaust means is applied after <PICT:1107265/C1/1> <PICT:1107265/C1/2> the lower pressure gas when a glass sheet, for example, reaches its strain point. The method is particularly useful in the differential toughening of curved windscreens. Here a curved heated sheet 23 is placed between a pair of opposed quenching frames 17 containing a plurality of cooling nozzles. The nozzles 13 in the central area are identical with those described above to differentially toughen that area, but those nozzles 24 on the periphery are ordinary aperture nozzles. |
