US1770103A - Furnace - Google Patents

Description

July 8, 1930. F. A FAHRENWALD 1,770,103

FURNACE Original Filed Jan. 18, 1927 rnwnn Illlll a m u N 15 1 .6 Prank AImhrenWdId L 0 Inventor Attornegs Patented 8, 1930 PATENT OFFICE FRANK A. ILHRENWALD, OF CHICAGO, ILLINOIS FURNACE Application filed January 18, 1927, Serial No. 161,855. Renewed January 23, 1929.

This invention relates to furnaces-and especially to those of the type having internal mechanical conveyors for passing metallic articles through a heated chamber for heat treating purposes, as for example in annealing sheet steel. The objects of the invention are the provision of new, improved, and simplified means for conserving heat and maintaining within the furnace chamber an atmosphere of the desired chemical composition.

In the drawings I have shown a specimen furnace embodying my improvements. 'Fig. 1 is a longitudinal section, Fig. 2 an end elevation, Fig. 3 a transverse section, Fig. 4 a detail view of a preferred form of roll; and Figs. 5 and 6 illustrate difierent curves defined by the rolls.

The furnace comprises a floor 1, end walls 2, side walls 3, and an'imperforate roof 4, all made of thick, refractory heat insulating material. I have not illustrated the metallic frame work usually employed for strengthening purposes. This is presupposed. Formed g5 in the side walls are openings 5, 5, receiving the ends of horizontal rolls 6. I have illustrated the hot-type of roll constructed as set forth in my application filed October 12, 1925, Serial No. 61,989, namely: rolls made of high temperature alloy and so-designed as to run, without local c oling, at any temperature up to about 2000. F. However the pres- .ent furnace is not restricted to this type of roll.

These rolls are not located in a single plane, but higher inside the body of the furnace than they are adjacent the two ends thereof. The end walls are provided with slots 7 for defined by'the rolls may either be a continuous curve .as shown in Fig. 5 or a flat topped curve the ingress and egress of the sheets or other as shown in Fig. 6. The roof of the furnace side walls are kept tight. This is not difiicult to accomplish since the only necessary apertures therein are the apertures 5 for the rolls and these can be packed by the use of cover plates 10 having some kind of soft packin 11 therein like asbestos or magnesia. It wil beremembered that the speed of the rolls isveryslow and the gas ressure very low.

I do not limit mysel f to roll type conveyors nor when rolls are used do I limit myself to any one type or shape of roll. I prefer the roll type furnace using non-cooled rolls be- *,cause of its simplicity and economy but my invention does not depend thereon. I have shown disk-type rolls in Figs. 3 and 4 because of the fact that many prefer them for sheet furnaces, but plain cylindrical rolls in Fig. 1 which can also be used for sheets and are preferable for bars, pallets, and odd shapes.

do not limit myself to any one kind of heating although I prefer electrical heating for ments 12, 12 in Fig. 4 located above and below the rolls. As this type of heatingrequires no gas-flow it is easier to maintain a uniform chemical condition inside the furnace than with a full fired furnace, and the economy of hot gas produced by the shape of the furnace enables electricity to be used economically. Indeed with a proper insulation of the furnace walls and t e use of noncooled rolls the heat consum tion becomes very nearly proportional to t e tonnage of material operated on, with only a small heat loss. No doors or other closures are required for the slots 7 although their unnecessary or obstructive use does not serve to distinguish from my invention.

Having thus described my invention what I claim is -which purpose I have shown resistance elev 1. A furnace of the character described comprising, in combination, a chambered structure of refractory material havin ingress and egress openings, conveyor rol s in said furnace, said rolls having axial. extensions which traverse apertures formed therefor in the side Wall of said chamber structure, said rolls constituting a mechanical conveyor, portions of said conveyor inside the furnace chamber being elevated above the level of said openings and the roof and vvalls of said furnace being substantially gas-tight, and means preventing escape of hot gases through the apertures around said rolls.

2. A furnace of the character described comprising, in combination, an elongated chambered structure of refractory material having ingress and egress openings at opposite ends, a mechanical conveyor extending through said furnace from a point outside of said ingress openingto a point outside of said egress opening, said conveyor comprising a series of parallelhorizontal rolls, certain offthe rolls inside the furnace chamber being'elevated above the level of said openings, said rolls having axial extensions which traverse apertures with which the side walls FRANK A.

whereof I hereunto am; my

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