US1830481A

US1830481A - Induction electric furnace

Info

Publication number: US1830481A
Application number: US378622A
Authority: US
Inventors: Northrup Edwin Fitch
Original assignee: Ajax Electrothermic Corp
Current assignee: Ajax Electrothermic Corp
Priority date: 1929-07-16
Filing date: 1929-07-16
Publication date: 1931-11-03
Anticipated expiration: 1948-11-03

Description

Nov. 3,-1931. E, F. NoRTHRUP 1,830,481

INDUCTION ELECTRIC FURNACE Filed July 16. 1929 4.0 tion by one Patented Nov. 3, 1931 UNITED s'rAT'Es PATENT; orFlCa EDWIN FITCH NORTHBUP, OF PRINCETON, NEW JERSEY, ASSIGNOB TO AJAX ELEC- T ROTHEBIIC CORPORATION, Ol' PARK, NEW JERSEY, A CORPORATION OF NFW JERSEY Application med July 1s, i929. serial m. 378,622.

My invention relates to furnaces which are intended to'hold a content or charge of material which is leasilycontaminated by the Crucible used. 5 A purpose ofthe invention is tomake a furnace \crucible of sectional construction comprising all light sections which are easily formed and easily handled.

A further purpose is to form a Crucible of Y 1Q. horizontally divided sections, electrically Conducting or non-Conducting according to I' the needs of the furnace.

' lA further purpose is to Aapply sectional furnace construction to electric induction .15 furnaces, making each section a separate in? ductor secondary and placing the secondaries electrically in parallel.

A further purpose is to provide a furnace made uplof sections which may be held to'- gether by their weight and whichmay be sealed further and additionally secured in position b 'aj surrounding tamped finely dividedre actory. A further purpose is to provide a furnace p, "'5 made up ,of a series of rings divided in horizontal planes permitting variation" in the shape of the furnace by change inthe rings selected. Y

A further purpose is to provide a furnace particularly suited to the melting of glass of special quality.

A further purpdse is to provide a furnacewhich is readily manufactured-from materials which are-difficult toV cast in large units but which may be very desirably free from contaminating ingredients.

` Further tpurposes will appear inthe specifiction an i the claims.

I have preferred to illustrate my invenneral form only, selecting a form which 1s practical, ellicientxand relatively in 've and which is well suited to the'service for which it is intended.-

Figures 1 and 3 are'central vertical sections lof slightly diierent'forms of my invention. i I

" Figure 2 is a section taken upon line 2--2 .of 1ligure 1 i e 4 is a erspective view of one of i therlsofmyfrn ce INIDU'CTION ELECTRIC FURNACE In furnace practice considerable diiliculty is found in handling" some of the charges because they are quite sensitive to contamination by the materiall of the Crucible or otherccontainer in which they are held. In some arts this seriously interferes with proper heating, melting and holding of the charge.

'One example of this is found in the glass art where high grade glass intended for optical uses or for Pyrex glass has been found to be very' easily contaminated by the usual crucible materials.

vGlass is electrically non-conducting and the heat must bedeveloped in the container. Glass melts at a low enough temperature to l be melted within a metal pot or Crucible, but

the'met'als whic are best suited otherwise for Crucible purposes are not free from contaminating effect upon the glass. On the other hand some of the best metals from the -rious alloys of tungsten carbide and nickel which are non-contaminating with respect to glass and excellent for the purpose 1n varying percentages of carblde and mckel and operate Well with 80% tungsten carbide and 20% nickel. This alloyis difficult to east in large units.'k

My invention is designed to make metals and such alloys fully available for furnace purposes byproviding for sectional furnace construction. It offers a sectional' construcltion which is simple`and inexpensive and which hasmany advantages in addition to its adaptability for use with special metals.

Describing in illustration and not in limitationzf The furnace illustrated is made up'V of rings which can be separately cast and iinished and can be built up into Crucible form by mounting one ring upon another ntil the desired furnace height is reached.

Crucible 5 is made u -of 'a base 6 and a plurality of rings? which maybe of equal diameter to make a cylindrical crucible, as in Fi re 1, .or of different diameter as at 7 in igure 3 or shape to give any desired contour to the furnace.

The invention is particularly well suited to the coreless t e of electric induction furnace, such as in igures 1 and 3. v

In these figures I have shown a coreless type furnace inductor 8 surrounding the composite crucible and supplied with electric current as conventially illustrated byl leads 9 and 10 across which-is placed powerfactor-corrective capacity 11. The turns of `the inductor maybe water-cooled if desired whenever the temperature Ato be attained.]us

tiies it.

The coil is shown as insulated interiorly at 12 by any-suitable'shell 13, such asl micanite, and is spaced' from the crucible at 14 by any suitable material or materials which will shown-may e ge.

Ben th the crucible the refractory rests upon an suitable bottom 16'which is extended to carry the coil at 17 The`furnace is encased within an outer frame 18 supported b trunnions 19 from links 20 f y The outer frame or shell 21 may be of non# magnetic material .as in Figure 3, ormay be magnetic and be protected from stray field by any suitable meanssuch as ma turn. circuit 22.v Such a magnetic return circuit should be laminated and may convenientl extend across beneath the bottom of the ace as well as up the sides at any desired number of locations about the furnace circumference.

I have shown a conventional ofthe upper part of the furnace. in the spacing of the outer'fra'nie or shell 21 from the refrac- .horizontal parallel .ary paths in Vparallel withinwliich current tory 15 byfa ring 23 .of some such material as asbestos lumber. v Y

Y In Figure 3=thei`bottom is supported from the lower artv of the shell by a spacer`24.

-It will llie evident that the subdivision of the crucible into sections is desirable whatever the sections and that subdivision alo planes provides secon 'will be induced b v-the normal vertical fur- A iliace inductor-J The resultant structure 'is therefore 'of maximum advantage from standpoints both of construction and operation. It further reduces repair and replace-V vided refractory fractory meut costs since in case of inury the par@ ticular section injured alone will need be replaced. f f

For most of the services requiredthe env Vides heat insulation, additionally insuresv against displacement ofrthe sections from their sealing contact and closes the s ace about the sections against passage of lea a e charge which may tend to pass through t e joints between the sections.

The holding power of the-.tamped refractory and of the refractory section at the top ofthe furnace are uite desirable to hold the sections against re ative movement during pouring. v

In view of my invention and disclosurevariationsl and modifications to meet individual whim'. o'r articular need will doubtless become evi ent to others skilled in the art to obtain all or part of the benefits ofvmyinvention without copying the structure shown, and I, therefore, claim all such in so far as they fall within the reasonable spirit and,

sco` of m invention.

aving us described my invention, what ters Patent is:-

section and metal rings restin upon the bottom and successively u on eac other to make up the side walls of .t e crucible.

' 2. A furnace crucible having side walls of electrically conducting metallic rings adapted to rest one upon another.

3. A furnace crucible having side walls of electrically conducting metallic adaptedtorestoneu nanotherand contaminating e ect upon the intended melt.

4.- An induction electric furnace crucible comprising a bottom section, a lurality of detachable short electrically con ucting me tallc one on another and a coreless inductor surrounding the crucible' and adpted to induce secondaryllow of current iii e sections in 5. In an electric induction furnace, a crucible made up of horizontally dispod metallic rings resting one upon another, an inductor coil surroun the crucible and finely dirammed between the. coil and crucible and adapted to hold the rin in position by firm engagement with their `exterior surfaces.

^ 6. A crucible comprising a bottom section and a lurality of rings together forming side wrs, a refractory material outside the rings, an' inductor coil surrounding the reand a magnetic circuit for return flux outside of the inductor.

froml 7. A crucible adapted to form Valt` of a furnace bodlylfngnd comprising an Sloy lof tungsten carbide and-nickel.

8. A crucible ring adapted to form part of a furnace body and comprising an electrically conductive metal dicult to cast in large units.

9. A glass melting furnace comprising a bottom section and rm of an alloy of tungsten carbide and nicke a. refractory packed about the crucible .and a furnace inductor surrounding the refractory and crucible.

v10. A glass melting furnace comprislng a bottom section and rings of an electrica ly conducting metal non-contaminatin to glass, a .refractory packed about the cruci le and a.

furnace inductor surrounding the refractory and crucible.

EDWIN F. NORTHRUP.