GB573287A - Improvements in or relating to heat treatment furnaces - Google Patents

Abstract

573,287. Heat - treatment furnaces. ELECTRIC RESISTANCE FURNACE CO., Ltd., and COOK, A. J. Feb. 15, 1944, No. 2764. [Class 51 (ii)] In a furnace for the heat treatment of metals of the kind in which a protective atmosphere is maintained within the furnace chamber under open door conditions by a gaseous screen in front of the door opening, the gaseous screen is delivered by a chamber 4, Figs. 1 and 3, disposed externally and in front of the furnace chamber immediately below the door level through a slot 9, gases being supplied to the chamber under pressure either before or after combustion. As shown in Fig. 1, gas from a pipe 11 and compressed air from a compressor 13 and pipe 15 are supplied to interconnected threeway valves 12, 14 respectively, which are operated simultaneously by a lever 16. In the position of the lever shown, gas and air are supplied through pipes 17, 18 to a combustion chamber 2 which delivers gases to the furnace, while in the position of the lever shown in dotted lines, gas and air are supplied to the screen chamber 4 through pipes 19, 20. Interlocking means are provided between the valve-operating and furnace door-actuating means as described in Specification 562,162. Fig. 5 shows a modification in which gas and air supply valves are actuated simultaneously by a lever 16 to supply a burner 52 delivering into a combustion chamber 2 from which the gases pass through pipe 53 to a three-way valve 44 and thence either to the furnace 1 through the pipe 54 or to the screen chamber 4 by way of a pipe 55, booster 56 and pipe 57. The valve 44 is interconnected with the valves 45, 48 so as to be operated simultaneously therewith by the lever 16 which is also interlocked with the door-actuating mechanism. Specification 562,297 also is referred to.