Toughened silicate glass pane with slight bulge - obtd. by pressing hot pane between dies, and used esp. for frameless windows in motor vehicles

摘要

The edge of the pane remains in one plane, but the bulge extends in two directions in the pane and has a height of 0.5-3%, esp. 1.8-2.2%, of the smaller length of the pane. The bulge pref. has a uniform radius over the entire surface of the pane, which is pref. larger than 40 x 40cm. and esp. with edge lengths of 60-140 cm. The rim of the pane pref. has a flat zone 2-3 cm. wide, extending along the entire perimeter of the pane. The prestressing at the edge of the pane is pref. 1200-1350 kp/cm2, and 700-900 kp/cm2 in its middle zone. The pane is pref. 3-6 mm. thick, and is moulded between a curved male die and a female die consisting of a flat frame touching only the edges of the pane. Esp. as frameless windows in motor vehicles or protective cabins, where the invention prevents the flip-flop effect, i.e. bulge reversal under stress.