Abstract: An annealing lehr comprised of a plurality of serially arranged heating and cooling sections which form a continuous treating chamber through which the ware passes during the annealing operation. An endless foraminous conveyor belt moves through the treating chamber and supports the ware to be annealed, with both the charging and return flights of the belt being located within the heating section to pre-heat the return flight. At least one burner is mounted adjacent the top and at each side of each heating section, and the burners fire directly into a duct which communicates with the inlet of a fan positioned centrally above the treating chamber. The circulating system includes down ducts at each side of the treating chamber and electrical heating elements can be located in the down ducts for providing the necessary heating, in lieu of the gas burners.

Abstract: This disclosure relates to glass annealing lehrs in which glass ware is supported on an endless conveyor to convey it through a closed tunnel consisting of separately controllable temperature zones which expose the ware to a glass annealing temperature gradient produced and maintained by gaseous fuel burners and electrical heaters employed separately or jointly, depending upon the availability of the fuel or electrical energy. In accordance with the invention, circulating fans are positioned at both sides of each lehr section, and air inlet ducts are provided for admitting controlled amounts of ambient air to the inlet of each fan.