US1692478A - Electric furnace - Google Patents

Description

J. WEINTZ ELECTRIC FURNAGE Filed Jan. 26, v1927 2 Sheets-Sheet 1 Nov. 2o, 192s.

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Nov. 20, 1928.

J. WENTZ ELECTRIC FURNACE Patented Nov. 20, 1928.

UNITED STATES PATENT OFFICE.

JACOB WEINTZ, OF CLEVELANlL-OHIO, ASSIGNOR T0 THE STRONG, CARLISLE &. HAM- MOND COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

Application tiled January 26, 1927.

rlhis invention relates to furnaces and particularly to so-called electric furnaces such as are commercially employed ind ustrially in heat treating metallic articles.

Furnaces of the type to which reference has been made comprise principally a chamber lined with refractory material around the sides of which are spaced a number of heating elements adapted to be broughtto incandescence by the passage of electric current therethrough, these elements being also spaced from the refractory lining which be comes heated in use also to incandescence and thus radiates and distributes the heat generated in the incandescent heating element.

It is the object of my invention to provide a surface conformation of this refractory lining which will take the utmost advantage of the incandescence of heating elements in receiving heat radiated therefrom toward the furnace walls, and return the same between the elements to the articles placed in the furnace for treatment.

The exact nature of the invention together with advantages arising therefrom will be obvious from the followin description taken in connection with the rawings in which Fig. 1 is a typical horizontal section through such a furnace in which my invention has been incorporated; Fig. 2 is a vertical section through the same,A as along line 2 2, Fig. 1; and Fig. 3 is an enlarged detail showing the manner in which the heat is distributed by my construction.

Referring now to the drawings the furnace is generally of the usual and well known construction com risin a. heating chamber 1 immediately orme by a rectangular box of a very high grade of refractory material 2. This refractory material is backed by a la er of fire brick 3 insulated by a layer of as estos 4 from a thick covering bf heat insulating material 5 contained within a Ine. tallic outer covering 6. The refractory material 2 thusforms in fact a lining for the heating chamber of the furnace, access being had to this chamber through an opening 7. Spaced as indicated in Fig. 1 along the side and rear walls of the furnace are a number of vertically extending heating pencils or eleneents 8, preferably of circular section, each po.c itioned between a pair of contactors 9 by which an electric circuit may be directed through the -several heating elements to ELECTRIC FURNACE.

Serial No. 163,704.

bring the same into incandescence, all in a well known manner.

When the heating elements are brought into an incandescent state it is evident that the laws of light transmission; the return y angle of a secondary radiating surface such as the refracting lining 2 herein, bearing the same relation to the angle of incidence as would a. light ray originating in one of the heating elements herein pass to the lining and be refracted therefrom.

'In order to take full advantage of this fact I form that portion of the material 2 immediate to eachof the heating elements 8 of parabolic section as indicated in Figs. 1 and 3, the focus of each parabola being the center of its corres onding heatingelement.

In order that t e heating elements be s aced as closely as possible and, therefore, t at a larger number of elements maybe employed `on a wall, the parabolic sections are not greatly extended, that is, only a relatively short portion, that of greatest curvature, is employed. In fact, such portion as is employed approximates in section very closely a circular arc. With such an arrangement the heating elements in order that they may be located at the foci are spaced vsomewhat from the general plane of the wall, andy in fact ina plane spaced somewhat forward of the plane in which the sides of the depressions meet each other, the side portions of adjacent depressions Joinlng each other from `ridges parallel with the heating elements and having gradually sloping sides.

The natureof the result of this arrangement is illustrated diagrammatically in Fig. 3.y Heat is radiated generally directly toward the center or contents of the furnace from each of the incandescent heating elements as along the radial broken lines from the front or inner faces of the elements. The opposite orvrear faces of the elements however, radiate only toward the lining 2. rlhe lines of heat transmission are radial in this case also, but owing to the parabolic surface conformation of the lining provided, this heat is returned or re-radiated along lines substantially perpendicular to the general surface of the lining, that is upon the rectangular system by the light full lines in Fig. 3. At the inner corner of the heating chamber the parabolic curvature of the lining has" been modified. as indicated at 11 according to4 the same system whereby the lines of most etcient radiation are from that portion of the lining towards'the center of the furnace.

The result of my invention is a greater temperature in the working partof the furnace than has heretofore been accomplished with the same size of elements, and a more uniform distribution of heat in this area.

What I claim is:

l. In a furnace having a Wall, a refractory lining therefor having parallel depressions of curved section the side portions of which meet at an angle to form ridges, and parallel heating elements spaced forwardly of the plane of said ridges and one before each of said depressions.

2. In a furnace having a Wall, a refractory lining therefor having shallow parallel depressions of parabolic section the side portions of which meet atan angle to form ridges, and heating elements located one along the focal line of each depression and spaced forwardly of the plane of said ridges.

3. In a furnace having a pair of Walls arranged in angularly disposed planes to moet along a line, refractory linings for said Walls havinfr depressions parallel with said line and of curved section, adjoining side portions of adjacent depressions, one of each Wall, meeting along a line substantially farther removed from the line of meeting of said Walls, than the general plane of the face of either linin is removed from the face of the correspon ing Wall.

In testimony whereof I hereby afiix my signature.

JACOB WEINTZ.

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