PURPOSE: The titled method having improved workability and productivity, wherein deeply bent plate glass has sleeve parts not to be curved reversely, having given curvature, by using radiant heat of heat source of a furnace without requiring wiring operation of heater wires for partial heating of plate glass.
CONSTITUTION: The partial heating of parts of the plate glass 1 to be curved deeply is carried out in such a way that radiant heat from a heat source of the side wall 6 of a furnace is reflected to the sleeve parts 2 of plate glass by the thermic ray reflecting plate 7. The thermic ray reflecting plate 7 is preferably kept at least ≥50mm apart from the sleeve parts 2 of the plate glass 1 so that the sleeve parts 2 of the plate glass 1 are partially heated. The thermic ray reflecting plate 7 may be set to heat the sleeve parts 2 of the plate glass 1 from the bottom, or from the top, or from both the sides. If necessary, the plate glass may be strengthened (cooled gradually) by air flow after processing of curving.