To make it possible, when the temperature of glass is elevated in a method to heat plate glasses, that the temperature does not rise too high in a pre-heating process at the time of starting and does not drop too inefficiently low at the time of finishing so that an optimum and high heat transfer coefficient is maintained by controlling the heat transfer coefficient for convection- heating by increasing the rotating speed of a hot air fan in order to increase the volume flow of blast air.
A furnace consists of a preheating furnace being operated on the principle of convection heating 1, a radiation heating furnace 2 and a cooling facility for tempering or heat strengthening 3. For the furnace 2, resistance members 10 are installed above the below a roll conveyor. For the cooling facility 3, nozzle boxes 11 are installed above and below the roll conveyor. There are nozzle boxes 4 in which a fan 5 (rotating speed is controlled at any time) adjacent to the inside of the furnace and the surface of plate glass is equipped to circulate hot air. There are heating resistances 6. A temperature sensor 12 regulates electric power to be supplied to the heating resistances 6 using a controlling device 13 so that the air temperature inside the furnace is kept at a preset value.
BEEMASU YUTSUKA
REETO ESUKO
Next Patent: METHOD FOR CUTTING GLASS RIBBON AND DEVICE THEREFOR