Car-Bottom Furnace

an industrial furnace in which the products are transferred from the charging hole to the discharging hole on a conveyor during the heating process. Such furnaces are used for heating metal products before pressure shaping and during heat treatment, as well as for drying foundry molds. Car-bottom furnaces are classified according to design as furnaces with conveyors below, on, or above the hearth.

In a car-bottom furnace with a conveyor below the hearth the conveyor chains are located in channels in the hearth, and only the carriers, to which the products are attached, are in the heating chamber of the furnace. The chains work at a temperature lower than the temperature to which the products are heated. In such furnaces sheet metal is heated at 900°C. The length of the furnace does not exceed 25 m. The chains of the hearth conveyor are located in the heating chamber of the furnace, and their temperature is equal to the temperature to which the product is heated. Products are heated to 600°C in car-bottom furnaces 15–20 m long with hearth conveyors and to 800°C in furnaces less than 5 m long. Such furnaces are used for heat treatment of rails and heating nonferrous metal products.

The chain of a trolley conveyor is located above the heating chamber of the furnace. The furnace crown has a slot through which the hangers with the carriers enter the heating chamber. Car-bottom furnaces with the conveyor above the hearth are used for firing enamel in the production of dishes, refrigerator bodies, and so on. Car-bottom furnaces are heated by gas, liquid fuel, and electrical resistance heaters.