| 摘要 |
<p>1395987 Treating vitreous material GLAVERBEL 23 Oct 1972 [25 Oct 1971] 48783/72 Heading C1M A body of vitreous or partly vitreous material is treated in a gas-filled treatment chamber (other than the drawing chamber, or annealing lehr associated therewith, of a drawing machine), in at least one zone of which the temperature of at least one face of the body is sufficiently high for the geometry of that face to be influenced by the heat distribution in the gas, gas-displacing forces being exerted first in one direction and then in a reverse direction to cause the gas in the said zone to move to and fro in contact with the said face. Preferably the forces are exerted at at least 1 cycle in 10 minutes, and up to 10 cycles per minute. The chamber may be an annealing lehr 37 in which a glass ribbon or sheet 43 is supported on rollers 44. Transverse motion of the gas to and fro above the sheet is caused by alternate injection of gas from tuber 45 and 46, which are supplied with gas from reservoir 52 and distributer 51. The treatment is preferably carried out in the zone in which the glass has a temperature of 450-600‹ C. The gas injected may be preheated air, or may be a combustible gas. Mechanical means, e.g. propellers or reciprocating plates, may replace the injectors. In an alternative embodiment (Fig. 4, not shown) the gas-displacing technique is used in a process for bending glass sheets by sagging into a concave mould.</p> |
