US1268685A

US1268685A - Electric-resistance furnace.

Info

Publication number: US1268685A
Application number: US13735416A
Authority: US
Inventors: William D Coolidge
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1916-12-16
Filing date: 1916-12-16
Publication date: 1918-06-04
Anticipated expiration: 1935-06-04

Description

W. D. COOLIDGE.

ELECTRIC ReslsrAnE FunNAcE.

APPLICATION FILED DEC.\.196.

Inventor:

William DCoolidgge,

' His Dttorneg.

UNITED STATES PATENT OFFICE.

WILLIAM D. COOLIDGE, OFSCHENECTADY, NEW YORK, AssIGNOn. TO GENERAL ELECTRIC COMPANY, a CORPORATION OF NEW Yonx. i

ELECTRIC-RESISTANCE rUnNAcE.

Snecma-,ation of Letters Patent.

'Patented June 4, 191.8.

Application nled December 16, 1918. Serial No. 137,354.

. sistance Furnaces, of which the following or other cooling fluild, admitted throughv lthe tube. At the opposite is a specification.

The present invention comprises a novel resistance furnace having a heater tube of refractory material, the object of the in* vention being to provide a simple, rugged furnace capable of operation at temperatures up to 2500o C., or more and adapted to maintain a' high vacuum or inert atmosphere about the object to be heated.

The novel features of my invention will be pointed out with particularit-y in the appended claims and a detailed description of the invention will be given in connection with the accompanying drawings of .which Figure l illustratespartly in perspective and partly in vert-ical section a furnace embodying my invention, and Fig. 2 shows in section details of a terminal adjacent to the cover plate.

As shown in the drawing, the furnace comprises a heater tube 1 of highly refractoryy material, preferably tungsten, at one end of which is joined a plug 2 of a metal of high electrical and heat conductivityfor example, copper, which clges the end of end a ring 3 of like metal -is joined. The copper is preferably'rst treated while `fused with oxidizable boron material to remove dissolved gasesand is then cast in a vacuum in con-l tact with the tungsten, as described in my prior Patent, No. 1,162,341. In this way an intimate molecular adherence of the two' metals is secured. Surrounding the heater tube and spaced away therefrom is an inclosing envelop or tank 4, which is provided with an outer jacket 5. affording a space through which a cooling uid may be circulated. On the Outer surface of the tank 4 spiral baffle plates 6 are located to cause a circulation about the tank Of water a tube 7 and exhausted through a tube 8. Between the' plugv 2 at the lower closed end of the heater tube and the tank 4 is' provided a yielding or floating electrical connection, preferably a body 9 0f liquid lmetal, such as mercury which permits expansion and contraction of the heater while preserving good electrical connection. A cooling y coil 10, immersed in the mercury maintains a desired temperature during the operation of the furnace. Suitable gas`tight inlet and outlet tube of the cooling coil.

The Contact ring 3 is mechanically fitted within the end of a metal tube 13 which passes through the cover plate 14 of the tank 4. The cover plate is maintained firmly pressed against the tank 4 by bolts 15, suitable insulating gaskets 16, 17 of fiber, rubber or the like, being provided to insulate the cover from the tank and the bolts 15. The cover is cooled by means of a coil 18, having an inlet tube 19 and an outlet tube 20. vA contact plate v21 joined to the tube 13 is fastened to the cover plate 14 by bolts 22, suitable washers 23 of lead or the like being provided to make a gas-tight joint. A split clamping ring 24 best shown-in Fig. 2 surrounds the tube 13 at .its junction with the

packed couplings

11, 12 are provided for the ring 3l on the open end of the heater. It is ythe tank may be evacuated or charged with gas through a tube 28, and is shown as communicating with a vacuum pump through a chamber 29 containing a drying agent 30 such as phosphorous pentoxid. The space 'Within the heater tube maybe se arately evacuated, or charged with gas. Vs indicated the end of the charging tube 13 is closed with a.v cylindrical 'stopper 31 communicating with a tube 3 2, and provided if desired with a window for observing the interior of the' heatertube A gasketl33 of u rubber secures a vacuum-tight jolnt.

l A heating current for the heater tube is i supplied by conductors 34, 35, connected respectively to the tank 4 and thegcontact 21. A furnace constructed as above described with artificially.cooled electrical terminals in intimate contact with the heater and located within the inclosing tank, may

be heated up with great rapidity` with a siifliciently heavyl current Without weakening or increasing the electrical resistance of the contacts.

What I claim as new and desire to secure by vLetters Patent of the United States, is: 1. An electric furnace comprising a heater tubef consisting of refractory material, a

plug of metal of -good heat and electrical conductivity molecularly joined to and 'clos'-r ing one endof said tube, an inclosing'metal tank spaced apart from said heater tube, a

yielding electrical connection between said .A inclosed end of theheater tube and the tank,

an insulating -sealj between the opposite end of Vtheheaiter tube and said tank, and electrical connections respectively. for said tank, and -for the'end of' the heater tubeopposite the end in electrical contact with said tank. 2. Anelectric furnace comprising a heater tube of tungsten, a plug` offcopper joined to and closing -one end of said tube, a copper contact ring joined .to the opposite open end cf said tube,- a metal tank inclosing said tube, a yielding electrical connection between said plug and said tank, a metal cover f for said tank electrically in contact .with

` a conducting liquid between the opposite end4 of said tube and said casing, and'electrical said heater tube, an insulating seal between said cover and said tank, and electrical connections respectivelyfor said tank and said cover.

3. An electric furnace comprising a substantially gas-tight hea-ter tube of refractory material, means for removing or intron` ducing gas to said tube, means for conducting a heating current thereto, and a sealed inclosing envelop spaced apart from said vheater tube and adapted to be separately evacuated or filled with gas.

' 4. A vacuum furnace comprising a heater tube of refractory material, a metallic casing'for said tube spaced apart therefrom, a quantity of mercury in said cas-ing, means for cooling said mercury, a plug of good conducting material joined to one end of said heater tube and contacting with said j mercury, andvelectrical connections respec-"i tively n for the oppositeend of said tube and for the metallic easing.

' 5. A furnace comprising a heater tube ofrefractory 'materiah al metal casing spaced vapart therefrom, an insulating seal between one end ofy said heater tube and said casing,

' from said casing.

connections respectively for saidlcasing and Ifor the lend of said heater tube insulated 6. An electric Vfurnace comprising a resistor of refractory material inclosing a heating zone, a metal casing spaced away vfrom said resistor comprising a tank and within said tank, lm'leans for artificially cooling said contacts, a. tube for introducing a charge to be heated into said resistor tube communicating with said resistor tube and projecting outside of said tank, and electrical connections for said contacts.

8. An electric fui-.nace comprising a tunesten'tube closed at one end,` a gas-tight casing surrounding said tube and spaced apart therefrom, a quantity of Aliquid metal in contact with the closed end of said tube, a charge-receiving tube electrically connected to the open end of said tungsten tube and projecting through sa'id casing, means i for evacuating or filling with gasthe space between said Vtungsten tube and said casing independently of the space within said tube, and electrical connections for the respective ends of said tungsten tube whereby a current for heating the tube may be conveyed.

9. An electric furnace comprising a gasimpervous refractory conducting tube i sealed at one end, means for introducing and withdrawing a charge into the opposite end thereof, a gas-tight casing surrounding said tube and spaced away therefrom, a yielding electrical connection between the closed end of said ytube and said casing, an

electrical connection to the opposite end of said tube and means for evacuating the space between said tube and said casing in` dependently of the. space within said tube.

In witness whereof, II have hereunto set inyhand this 14th day of Dec., 1916.

-l/VILLIAM D. COOLIDGE.