Walking Hearth Furnace
Furnace, Walking Hearth
a continuous furnace through which heated items are transported by means of walking (mobile) beams. When the beams move upward, the item lying on the stationary hearth of the furnace is raised, and when the beams subsequently move in the horizontal plane (through the furnace), the item is displaced, or “walked,” a fixed distance along with the beams. The beams are then lowered, and the item is again set on the stationary hearth. At the end of the cycle, the walking beam, now located somewhat below the level of the stationary hearth, returns to its original position. In the course of repeating such cycles, the items pass through the entire furnace and are heated to temperature ranging from 950° to 1250°C.
Walking hearth furnaces have several advantages over pusher furnaces. Output is not limited by the maximum length of the pushing action, and the items are not damaged on the hearth by pushing. Heating of items is accelerated, as there are usually gaps between items on a hearth and between the items and the walls. The items are thus heated from three or four sides. No additional equipment is required to release the furnace from the blanks, and the losses through burning of the metal are reduced.
Heating in walking hearth furnaces is done either with burners located both above and below the items or only below the items. These furnaces are heated by gas or liquid fuel. Walking hearth furnaces are used in metallurgy and machine building for heat-treatment and preheating of metal blanks and items prior to pressure shaping at elevated temperatures.
V. M. TYMCHAK