US839983A - Electric furnace. - Google Patents

Description

No: asmss. PATENTED JAN. 1, 1907. w. H, BRISTOL;

E LEOIRIO FURNACE. APPLICATION FILED AUG. s, 1000;

Fig-1- 352 411! C1 l'l'ozucq avoid cracking of crucible or lining.

- WILLIAM H. BRISTOL, NEW YORK, N. Y.

ELECTRIC FURNACE.

Specification of Letters Patent.

Patented Jan. 1, 1907.

Application filed August 6,1906. Serial No. 329.334.

To all whom it may concern:

Be it known that 1, WILLIAM H. BRrsToL, a citizen of the United States, and a resident of New York, in the county of New York and State of New York, have invented certain heated by means of the electricity passing through a heating-coil of suitable resistancewire. I

It has for its object a furnace which may be quickly brought to full heat; also, a furnace into which the articles may be placed Without danger of short-circuiting or conterminating the heating-coil.

For this purpose my invention consists, essentially, of an electric furnace comprising a fused-quartz gsilica) receptacle forming a heating-chamber, an electric heating-coil about said receptacle, and a refractory nonconducting material or materials incasing said coil and chamber.

The nature of my invention will best be understood in connection with the accom panying drawings, in which Figure 1 is a vertical section of a crucible form of furnace. Fig. 2 is a transverse section of a tubular form of furnace.

Similar characters of reference designate corresponding parts throughout both views.

The present furnaces of this character utilize some refractory lining or crucible of magnesia or clay as a heatirig-chamber, into which the articles or materials to be treated are placed. Urucibles or chambers so formed are provided with starting resistances and considerable time (some ten to fifteen minutes) is required to bring the furnace up to a full heat. This is necessary to especially with the lincd heating-chambers, the articles or materials to be heated freuently permeate said lining or crucible and s ort-circuit or attack the heating-coil, causing it to break down.

In my improved furnace ldprovide a heating-chamber formed of fuse quartz (silica) in the shape of a crucible 11), Fig. 1, or a tube, Fig. 2, or of any form suited to the use to which the furnace is to be put. About this chamber is a heating-wirc 11, preferably of platinum, in the form of a coil and of suitable size to produce the required heat and of such AlSO,

resistance as to permit of its being directly placed across a predetermined difference of potential. T he successive turns of the coil are by preference insulated from each other by an asbestos cord 12, wound on together and parallel with the platinum wire, Fig. .2.

For the purpose of permitting a consider able amount of resistance-wire to be wound upon the quartz receptacle within a contracted space and in order to allow of the passage of suilicient current to produce the quantity of heat demanded 1 may make the said wire of flattened form and wind it edgewise with respect to said receptacle, as shown in Fig. 1. Bjy this means I am enabled to wind on 'wire of sufficient cross-section to carry the required current.

The quartz crucible or tube, with its sur' rounding coil, is preferably covered with asbestos 13 and the whole then incased in some refractory insulating material 141, as fire-clay, magnesia, &c., to prevent radiation. A suitquired The articles or materials to be heated are placed within the heating-chamber 16 and the full current sent through coil 11. he chamber 16 heats very rapidly, coming to a full heat in about one minute and a half. Owing to the peculiar property of the quartz, the crucible or lining does not craclr under the sudden changes of temperature, and the heat may be quickly turned on or oii without danger of cracking the quartz receptacle. The quartz also acts as a first-class insulator, and there is no danger of the articles or ma" terials short-circuiting the heating-coil 11 or of penetrating the receptacle to contaminate said coil. Of course substances which combine with the silica at the high temperatures employed must not be placed in direct contact with the walls of the heating-chamber.

What I claim as new, and desire to secure by Letters Patent of the United States, 18-

1. An electric furnace comprising: a fusedquartz receptacle forming a heating-chamher; an electric heating-coil surrounding the same; and a refractory, non-conducting material incasing said coil and chamber.

' 2. An electricfurnace comprisin": afueedquartz receptacle forming a heatingchamher; a platinum electric heating-coil surrounding the same; and a refractory, nonconducting covering surrounding said coil and chamber.

3. An electric furnace comprising: a fusedable refractory cover 15 is provided when re quartz receptacle forming a heating-chaml tacle and coil; and a refractory, non-con luctber; a'platinum electric heating-coil wound upon the same having its successive turns separated from each other by an asbestos cord; and a refractory, non-conducting coveriug surrounding said coil andc'hamber.

4; An electric furnace comprising: a fusedquartz receptacle forming a heating-chan1- her; acoll or flattened Wire placed edgewise with res ect to the quartz receptacle and surineun the same; and a refractory, non-- conducting covering surrounding said coil and chamber. 1

h 5. An electric furnace comprising: alusedquartz receptacle forming a heating-chamber; an electric heating-coil surrounding the same; an asbestos covering aboutsaid receping material incasing the same 6. An electric furnace comprising: a fusedquartz receptacle forming a heating-chamuer; an electric heating-coil surrounding the same, having its successive turns separated from each other by asbestos; an asbestos covering-about said receptacle and coil; and i a refractory,non-conducting material incasing the same.

York and State of New York, this 4th day of August, A. D. 1906.

WILLIAM H. BRISTOL. Witnesses: EREDK. F. S,GI;IUETZ,

SALLY O. YUDIZKY.

Signed at New York, in the county of New I

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