US1076887A - Electric melting-furnace. - Google Patents

Description

L. B. HOWARD. ELECTRIC MELTING FURNACE. APPLICATION FILE]? FEB. 6, .1909. 1,076,887, Patented Oct. 28, .1913.

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Specification of Letters Patent.

Patented'Oct. 28, 1913.

To all whom it may concern: Be it known that I LESLIE E. HOWARD, a citizen of the United States, residing at La Grange, in the county of Cook and State .of Illinois, have invented certain new and useful Improvements in Electric Melting-Furae of w ch the f l wing is pe fication.

This invention relates'to electric melting furnaces of what is known as the induction and is especially adapted for the meltmetals of the bronze and mg and refining f brass white metal types, such as copper, mixtures, Babbitt metals but may also ,be used for fining of iron and steel.

ng th le ding bj c tion areto, as far as possible,

e melting and reof my invenreduce the raaluminum, etc.,

. tion refer to a dieting surface of the containing walls 5 forming the melting chamber, ,thereby reducing the resistance and, as a result-of this, greatly forming th Secondary wholly or partially in an annular chamber of large diameter and small cross-section of the metal, as has been the practice form the melting chamber three dimensions o of the bath will conform more opencoal,

posing ,the' metal bath in such a manner closel to present practice as found in heart melting furnaces fired by gas, etc. To accomplish these various able results, I'have discovered that if the secondary is formed only in part of the molten bath to be operated on, substantially reatly inten metal,

increase current n inste d ,of (11 heretofore generally in furnaces of this type, to

f length, breadth parts in the different Fig. 1.

- with my device.

netic field, and one desirone-third of the secondary,'and the other? portion, substantially ondary, is formed of two-thirds of the seca solid mass of metal;

having a very large cross-section relative to the cross-section of the molten portion of the secondary, the end sought by the invention is accomplished. ther am enabled to place both the primary coil and the secondary, formed in part by the moltenbath and in part by the large mass of metal disposed as described, very close to the magnetic field, thus cutting down very largely the magnetic leaka e and loss which has heretofore been foun a serious objection in this type of furnaces.

In h a c p nyi g dra ng wh ch By this design I furrepresent invention, andin which corresponding numbers and symbols refer to corresponding I views,,Figure 1 is a vertical cross-section of the'furnace on the line 11.of Fig. 2, and Fig. 2 is a vertical longitudinal section on the line 22 of Induction furnaces as can be run on a single-phase alternating current only; but forcommercial reasons it is often desirable to use multi-phase alternating currents, and this I am enabled to do While the drawings and description formlnga part of this specificaadapted to a single-phase alternating cur rent by either running the two primary coils in multiple connection from the source of single-phase alternating current supply, or by pro'vidlng but one primary coil, one mag- 'air of contact blocks; while to adapt my esign to three or more phase currents, it is only necessary to pro- 'vide as many of the electric systems (comone practical embodiment of'the heretofore designed furnace built for two-phase alternating current, the design -is readily prising the magnetic field, primary coils,

secondary winding, and contact blocks) as there are phases to the electrical current sup- .each of said systems being in circuit with one phase only of the alternating current supply.

Referring to the drawings, 1 designates a closed magnetic field, formed in the usual manner of thin iron sheets built up with magnetic insulating material between the sheets in the manner usually employed in the construction of electrical transformer cores.

2 designates the two primary windings which are placed around the two lower limbs of the magnetic field 1, these primary windings being supplied byany suitabl-e source of alternating, pulsating or intermittent current of electricity, but more preferably two-- phase alternating current, which may be supplied by agenerator, as indicated diagrammatically at 2 The solid portion of the secondary circuit is made up of a pair of preferably dense castings of some suitable material such as copper, iron or st el, copper being preferable on account of its low electrical resistance properties. Each; "of these castings comprises a bottom horizontal member 3 and outwardly inclined or fiaringsides 4. These latter are provided with end flanges indicated at- 4 in Fig. 2', to which flanges are securely attached,'as by bolts 5, current-conducting blocks 6 of any suitable material, in some special cases graphite, but preferably of cast steel with a high melting point. It will be observed by reference to Fig. 1 that the blocks 6 have spout 13, these severaland as shown, integral. This housing an extended contact surface with the conductors 4, while the opposite surface, "in contact with the bath, indicated at 7, is relatively small. The blocks 6 are provided with water ducts or pipes 8 having end connections indicated at 8 and supplied with water through a hose9 for the purpose of preventing the blocks at their surfaces of contact with the bath from becoming molten.

Fitted around the upper and inner faces and ends of the contact blocks 6 isa housing forming, with said blocks, a containing chamber for-the bath. This housing comprises a bottom wall 10 lying between the blocks 6, side walls'll superposed on the blocks 6, and end walls 12, one of which latter is preferably formed with a pouring parts being preferably, or casing forming, with the contact blocks 6, a containing chamber for the bath, is of any suitable refractory material, strengthened somewhat and made more durable casing 14 of sheet iron or other suitable material surrounding the end and side walls thereof.

Between the bottom 10' of the melting chamber and the upper limb of the magnet 1 are disposed a series of pipes or ducts 15 suitably connected at their ends byreturn bends 16 and supplied with a cooling me dium as water, either independently or from the pipes 8 through-a connectin hose or pipe 17 (Fig. 2) the purpose of t ese pipes or ducts being to prevent the temperature in the magnet 1 from rising above a desirable limit as a result of radiation of heat from 'the molten bath 7.

The. melting chamber is conveniently closed at the top by a cover 18 of refractory material, which cover may be formed in sections, if desired, for convenience in handling, and is preferably strengthened on top by ribbed metal frame-plates 19 preferably made in two sections with a joint connected by bolts 20, said joint being insulated by suitable material such as asbestos, as shown at 21, to prevent any shunting of the induced current around the cover. The cover is locked in place on the melting chain her by any suitable or convenient means, as by links 22, pivoted at 23 to the lower ends f vertical loops 24 that are integral with or secured to the metal frame sections 19 for the application of the books of an overhead crane,-the links 22 engaging notched riveted to a pair of depending arms 29, the

upper ends of these latter having trunnions 3O rotatably journaled in bearings 31 on the upper ends of a pair ofstandards 32. The a lower limb of the magnet 1 rests on crossbars 33 that are riveted. at their ends to the lower sides of the beams 27.

A power device for tilting the apparatus c,

sufliciently to pour the molten bath through the spout 13"into a ladle or other suitable receptacle is herein shown, the same 'comprlsing the cylinder 34 containing a p1stong35, the piston-rod 36 ofwhich is pivotally connected at 37 with an ear or lug 38 formed on a cross-bar 39 riveted to and between the ends of the longitudinal'bars 27. The cylin- .d'er 34 is pivoted at its lower end at 40 to a supporting base 41, so as to be capable of rocking in the same direction as the furnace. The cylinder is provided at upper and lower ends with ducts 42 and 43, respectively, which lead into the circular casing 44 of a four-way valve 45, which latter is provided with an operating handle 46.

47 designates'a supply duct leading from a source of compressed air or any other suitable motive fluid, while 48 designates an exhaust duct on the opposite side of the valve casing from the supply 47. A pair of oppositely curved ducts 49 and 50 formed through the valve-b0dy serve to connect the supply and exhaust ports 47 and 48 with the cylinder'ducts 42 and 43, said ducts 49 and 50 alternately acting as supply and exhaust ducts, according to the position of the valve. f

In the position of the valveshown' in Fig. 2., the motive fluid has been admitted to the upper end of. the cylinder and exhausted from the lower end thereof, thus returning the furnace from tilted to. horizontal position. By lowering the valve handle 46 so as to transpose the connections of the ducts 49 and 50, the1motive fluid will be admitted to the lower end, which effects the tilting of the furnace and the pouring of the contents.

In operation, molten or solid metal is charged into the melting chamber in such a manner as to form an electrical connection between the cont-act blocks6. If the metal is charged solid, it is advisableto cut the bars of such a length that they will readily bridge over the 'space between the blocks 6, forming a contact with them. After the meltingehamber is properly charged with molten or solidmetal, as described, the electric current is caused to flow through the primary coils 2, setting up a strong magnetic flux in-a magnetic field 1. The mag- -netic flux in that portion of the magnetic field 1 which is immediately surrounded by the secondary circuit formed in part by the permanent members 3, 4 and 6, and-in part by the molten bath 7, causes an electric current of very low voltage but extremely high current density to be generated, partly in the molten metal and partly in the permanent conductors represented by the parts 3, 4 and 6, and that portion generated in the parts 3, 4 and dis caused to flow through the bath 7 by contact of the said bath with the blocks 6. The temperature of the, bath may be regulated by controlling the current passing into the coils 2, this control being effected 'by any of the, well known means, such as inductive resistance induced as shown diagrammatically at 2.. After the metalcomprising the bath 7 is sufficiently melted or otherwise treated, the connection of the coils 2 with their source of electric energy is broken,and the electrical action of the apparatus thereby ceases. The charge is then poured by manipulation of the valve of the power tilting device, as already described, and returned to normal position after the pouring. It is usual to pour only about from per cent. to 75 per cent. of the contents of the melting chamber, the remainder being left for convenience in closing the secondary circuit between the blocks 6 and fresh cold or molten metal, which is then placed in themelting chamber, and the procforming with said electrodeblocks and the ess as above described repeated.

Believing myself to be the first to disclose a melting furnace ofthe character described wherein the secondary circuit is formed partly of molten metal and partly of a permanent conductor arranged in series, I do not limit the invention to the particular apparatus herein shown and described, as it is evident that the same may be considerably modified by those skilled in the. art without involving any departure from the underly-' ing principle, or sacrificing any of the advantages, of the invention,

I claitn: -1'. An electric melting furnace having a multiphase transformer with a plurality of secondary circuits eachformed in series partly by a permanent conductor, said sec-""- ondary circuits adapted to be completed by the body of metal subjected to the action of the furnace.

2. In an electrical melting furnace, the combination of a transformer core, primary receptacleand having inner areas in contact with material within the receptacle to be melted, and heavyconductive U-frames looplng through saidtransformer core and connecting with said electrdde blocks and forming with said electrode blocks and the material within the receptacle substantially short circuited secondary circuits.

8. In an electrical melting furnace, combination of a transformer core, primary windings on said core, a trough-shaped receptacle of refractory material mounted on said core, electrode blocks extending at oppositepoints through the side walls of said receptacle and having inner areas in contact with material within the receptacle to be melted, and heavy conductive'U-frames looping through said transformer core and.

connecting with said electrode blocks and forming with said electrode-blocks and the material within the receptacle substantially short circuited secondary circuits, the conmaterial within the receptacle being restricted whereby the heavy current' flow material within the receptacle substantially short" circuited secondary. circuits, and a support on which said transformer core is ,tiltably supported.

' 5. In an electric melting furnace, the commetal series portion of a secondary circuit mounted thereon and having upwardly ex- .tending sides provided with contact blocks,

a rectangular core member embracing the intermediate base port on of said secondary, a prnnary coil surroundlngone limb of said core member, and a receptacle of refractory.

material surmounting said secondary and formed with apertured side walls through which said contact blocks. project whereby to form contact with the material to be operated upon in said receptacle.

6. In an electric melting furnace, the combination with a tiltable support, of a solid metal series portion of a secondary circuit mounted thereon andhaving upwardly extending sides provided with contact-blocks, a rectangular core'member embracing the intermediate base portion of said secondary, a primarycircuitcoil surrounding one limb of said core member, a receptacle of refrac- .tact areas of the'electrode blocks with the .bination with a tiltable support, of a solid 5110 be operated upon in'said receptacle, and

means for circulating a cooling medium'between said receptacle and core member.

7. In an'electric furnace, the combination, with a furnace basin, of an induction coil 10 whose secondary consists ofa fused portion of the bath within the basin, and an unfused conductor outside of and below the basin.

8. In an electric furnace, the combination,-

with a furnace basin, of an induction coil having an annular secondary circuit consisting partly of a fused ortion of the bath Within the basin, and t e remainder of an unfused conductor outside of and below the basin of relatively high conductivity compared with the fused portion of the circuit.

In testimony that I claim the foregoing as my'invention, I have hereunto subscribed my name in the presence oftwo witnesses.

LESLIE E. HOWARD.

Witnesses:

SAMUEL N. Pom), MArrm B. Buss.

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