US2166964A - Electric furnace roof ring - Google Patents

Description

July 25, 1939. w MOORE 7 2,166,964

ELECTRIC FURNACE ROOF RING Filed June 7, 1957 Patented July 25, 1939 UNITED STAT ELECTRIC FURNACE ROOF RING William E. Moore, Pittsburgh, Pa., assignor to Pittsburgh Research Corporation, Pittsburgh,

Application June 7, 1937, Serial No. 148,917

2/ Claims.

The present invention relates to improvements in electric furnaces, and more particularly to the roof arch supporting rings therefor.

Heretofore in the operation of electric fur- 5 naces, such for example as those used in metal- 1 lurgical operations, considerable difficulty has been experienced due to the burning away of the shell refractories adjacent the roof ring, causing' the refractories next to the supporting flange 10' of the ring to spall or wear away, exposing the roof ring. The consequent overheating of the roof ring soon causes oxidation, crumbling and cracking, and also causes upsetting-of the roof ring flange due to expansion.

An important object of the present invention is to overcome these difflculties by preventing overheating of the-roof ring and adjacent refractories, and by preventing upsetting of the ring flange due toexpansion.

Other objects and advantages will be apparent during the course of the following description.

In the accompanying drawing, which forms a part of this specification, and wherein like 25 characters of reference denote like parts throughout,

Figurel is a verticalsectional view through the roof of an electric furnace embodying the invention, and the adjacent portions of the fur- 30 nace crucible,

Figure 2 is a horizontal sectional view on the line 2-4 of Figure 1,

Figure 3 is a detail fragmentary vertical sectional view of the improved roof ring/and,

Figure 4 is a fragmentary detail sectional view taken on a horizontal plane through the roof ring. v

In the drawing, wherein for the purpose of 11- lustration is shown a preferred embodiment of the invention, the numeral I0 designates the metal shell of a furnace crucible having the-usual refractory lining II. A metallic roof ring I! having an upper inwardly projecting flange l3 and a lower inwardly projecting flange It sup- 45 ports the usual roof refractories l6 formed in an arch.

In practice the roof -ring rests upon the top of v the crucible, and is normally protected from the heat of the furnace by the refractories i5. Due to the intense heat to which they are subjected, the refractories often burn away, thereby exposing the metal of the roof ring to the heat of the furnace. This heating of the roof ring results in oxidation of the metal thereof and an upsetting action of the lower flange of the, ring. when tion are very severe because of the upsetting of the ring flange, and cracking consequently results.

To overcome this diillculty a water cooling pipe or channel It is arranged in the angle between the roof ring and its lower flange and ex-,

tends substantially completely'around the roof ring, having its ends extended out through the side of the ring for connection to suitable water' circulating conduits.- .In order to insure a dlrect transfer of heat from the lower flange of the roof ring to the cooling pipe It, the pipe is welded to the ring and its flange, as indicated at H. The roof refractories l5 surround the cooling pipe [8.

Despite the presence of the cooling pipe it, the inner edge of the lower roof flange I4 is often subject to overheating and consequent expandof the invention ing, which results in upsetting of the inner edge of the flange. When-the flange cools down, the contraction of the outer edge thereof is very severe, due to the upsetting caused by the expansion of the edge of the flange while the outer portion of the flange is much cooler and not subject to expansion. The contraction of the upset portion of the flange causes cracking thereof.

To overcome this difiiculty, radial slots l8 are cut'in the flange and extend from the inner edge of the flange to a point adjacent the welding l'iof the pipe It to the ring. The slots [8 are disposed at regular intervals-of a few inches about the flange l4, and when these slots are present, .no upsetting of the flange occurs when it is overheated, and no cracking occurs when it cools. The slots I8 provide for expansion of'the metal of the flange.

It will be seen that the water cooling pipe It and its connection to the roof ring prevent overheating of the ring, and that the radial slots l8 permit expansion and contraction of the inner edge of the lower flange it without cracking or damaging the flange. When a roof ring is formed with the cooling pipe. l6 and slots l8 it will not be subject to the usual damage and deterioration from overheating and the resulting expansion and contraction.

While I have shown and described the preferred embodiment of the invention it. is to be understood that various changes in the size, shape and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. In a furnace, a furnace crucible, a roof structure for said crucible, said roof structure comprising a metallic roof ring adapted to be supported on said crucible and having an .in-

wardly extending flange at its lower end. said flange being provided with a series of spaced slots extending to the inner edge of the flange, a cooling pipe extending around the interior of said roof ring adjacent the flange, and a refractory roof supported by said roof ring and flange.

2. In a furnace, a furnacecrucible, a roof structure comprising a metallic roof ring adapted to be supported on said crucible and having an inwardly extendingflange at its lower end, said flange being provided with a series of spaced slots extending radially inwardly from the inner edge of the flange to permit expansion and contraction of the flange, a cooling pipe extending flange. v

' WILLIAM E. MOORE.

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