pusher furnace[′pu̇sh·ər ‚fər·nəs]
a continuous furnace through which work-pieces being heated are moved across the hearth or hearth beams under the action of an electric or hydraulic pusher positioned behind the charge. Pusher furnaces are used in metallurgy and machine building to heat metal workpieces for hot pressure shaping or heat treatment. Furnaces of this type can heat workpieces within a wide temperature range (400°–1400°C).
Pusher furnaces are classified according to their design features. The largest furnaces are used in rolling mills. In wheel rolling or forging, the workpieces being heated, which are short, are pushed along guides with a U-shaped cross section. For heat treatment of small articles, coils of steel strip, stacks of plates, or wire reels, the workpieces are placed on trays and are sometimes covered with a muffle before being charged into the furnace. Pushing is the simplest method of moving a workpiece through a furnace; it requires comparatively simple equipment. However, flexible control of the heating regime is difficult, and the work-pieces are damaged by scraping against the hearth (this can be eliminated by using trays or liners). In addition, removal of the billet from the furnace is a laborious operation. Because of increasingly stringent requirements for heating quality, especially in heat treatment, pusher furnaces are being supplanted by more advanced types of continuous furnaces, such as walking-hearth or roller-hearth furnaces, rotary-ring furnaces, and rotary furnaces.
REFERENCESSpravochnik konstruktora pechei prokatnogo proizvodstva, vol. 1. Edited by V. M. Tymchak. Moscow, 1970.
Ivanova, N. I., A. A. Perimov, and V. M. Tymchak. Mekhanizmy pechei prokatnogo proizvodstva. Moscow, 1972. Chapter 1.
V. M. TYMCHAK