GB524970A - Improvements relating to furnaces for the heat treatment of metal objects - Google Patents

Abstract

524,970. Furnaces for the heat treatment of metal articles. WELLMAN SMITH OWEN ENGINEERING CORPORATION, Ltd., and SCHIELDROP, B. H. Feb. 14, 1939, No. 4885. [Class 51 (ii)] In an annular tunnel furnace for heat treating metal articles such as ingots, the charge is supported on a fixed hearth and the firing is advanced progressively around the furnace. In the furnace shown in Figs. 1 and 2, ingots 4 are supported on the fixed hearth 2 of the furnace 1 which has side walls 3 and a rotary annular roof 5. A partition 9 depends from the roof into the furnace and is arranged between charging and discharging openings 10, 11 in the roof. Burner ports 21 are arranged at intervals around the furnace and the gases are withdrawn through a flue 16 which rotates with the roof and communicates with a central outlet flue 19. During operation burners heat the charge adjacent to the partition 9 on one side of it and the gases flow around the furnace to the flue 16. When the ingot near the partition is sufficiently heated it is removed through the opening 11 in the roof which is then rotated a distance equal to the interval between adjacent ingots. The charging hole 10 is then over an empty position on the hearth and a fresh ingot is then inserted on the cool side of the partition. This cycle of operations is continued, fresh burners being put into operation as the roof is rotated and the burners previously in use being extinguished. In a modification the side walls rotate with the roof and the cross section of the furnace chamber is varied in shape. The burners are arranged to deliver through ports in the hearth. In a further modification the side walls only rotate, the charging and discharging openings and the waste gas exit being arranged therein. The burners may be controlled automatically.