US1235629A - Electrical induction-furnace. - Google Patents

Description

J. R. WYATT.

ELECTRICAL INDUCTION FURNACE.

APPLICATION HLED JULY 19. l9l6. 1,235,629. Patented Aug. 7,1917.

2 SHEETS-SHEET 2.

FIG. 6

13 l I i l l I l l l 5 Suva d 01 nnrrnn STATES JAMES B. WYATT, F PHILADELPHIA, PENNSYLVANIA, ASSIGNOB TO THE AJAX METAL COHYANY, INCORPORATED, 01F PHILADELPHIA, PENNSYLVANIA, A 6GB- POBATION OF PENNSYLVANIA.

ELECTRICAL INDUCTIGET-FUBETAGE.

Specification of Letters Eatent.

Application filed July 19, 1918. Serial No. 110,203.

To all whom it may concern.-

Be it known that 1, JAMES R. WYATT, a

' citizen of the United States, residing at 20% S. 21st St, Philadelphia, in the county of Philadelphia and State of Pennsylvania, have inventeda certain new and useful Electrical Induction-Furnace, of which the following is a specification.

The purpose of my invention is to utilize an electric conductor of the first class for the channel walls forming part of the secondary of a transformer, in order to-facilitate the melting and maintaining in melted condi-f tion of metals whose character prevents their advantageous use as complete secondaries for the transformers, adding the heating effect of the channel walls to that within the channel content.

A further purpose of my invention is to provide electric melting appliances suitable for melting, refining or maintaining in molten condition metals having a relatively low. melting point.

A further purpose of my invention is to discharge hotter molten metal along outside channel walls into opposite sides or spaced points of a molten bath in directions initially toward each other, withdrawing cooler molten metal along the inside channel wall at substantially the same points and maintaining a double circulation thereby.

A further purpose of my invention is to utilize an acute angle outside of the pool and preferably obtuse angles at the connection of the channel with the pool in the stirring of a pool having the same level as the molten metal in the channel.

Further purposes will appear in the specification and claims hereof.

I have preferred to illustrate m invention by but a few of the forms 0 the invention to which it may appear, selecting forms which are practical, etlicient and which at the same time well illustrate the principles of my invention.

Figure 1 is a: side elevation of one form of my'invention.

Fig. 2 is" a horizontal section upon line 22 of Fig. 1. i

Fig. 3 is a section upon line 3-3 in Fig. 1.

Fig. 4 is a fragmentary enlarged horizontal section of another form.

Fig. 5 is a top plan view of another form or my invention.

7 Fig. 6 is a section upon line 66 of Fig. 5.

Figs. 7 and 8 are a top plan view and section thereof upon line 88 showing another iorm of my invention.

Fig. 9 is a side elevation, partly broken away, of another form.

In the drawings similar numerals indicate like parts.

The form shown in Figs. 1 to 3 inclusive discloses a furnace 10 having a relatively high pool level and a channel 11 connected therewith, closed at the top and having its connections with the pool preferably at the samle height and well below the level ofthe poo The furnace comprises the outer-jacket 12 provided with a spout 13, a cap 14 connected therewith by cars 15 and bolts 16 and aPtop 17 carrying a conical refractory 18 which fits into a corresponding opening in an annular refractory 19 carried by the top. The 1acket 12 and the casing 20 are united by flanges 21, 22 and the casing is interrupted by flanges 28 and 2d, the several flanges being united by any means such as rivets 25. Thainterruption of the casing reduces or eliminates flow of secondary current through the casing.

The jacket 12 and casing 20 are lined by a refractory 26 which is crowded in about a form of wood or other suitable material the form being dividedinto two or more parts,

the body and channel parts separating for its most desirable shape is approximately rectangular and much higher in the sections taken than is its width. This is shown in Fig. 3 where the two channel legs 27 and 28 are shown as long narrow rectangles. l

have secured excellent results with a proportion of 3 or to 1.

.The transformerused in the first form illustrated is of shell type shown at 29 and comprises three legs 30, 31 and 32 with a laminated frame and a winding or windings here shown as placed at 33 and 34: upon the outer legs. It is air-cooled bywell-known means here represented by the nozzle 35 of any suitable air blast system not shown.

Induced flow of electric current in opposite directions in adjacent channels containing molten metal capable of acting as a conductor results in electrodynamic forces in both molten conductors in directions perpendicular to the lengths of the conductors tending to separate the conductors. These forces vary directly as the products of the currents fiowing in the two conductorsv the lengths of the conductors, because of the differing distances separating them, and cause correspondingly varied hydro-dynamic forces, tending toproduce motion of the molten metal arallel to the lengths of the conductors. T is application of motor effect causes motion of the molten metal and hence circulation, if the molten conductoror fluid be free to fiow.

The motor effect may be intensified by bringing the conductors together into an angle, as it is utilized by me, and becomes most effective with an acute angle, increasing within reasonable limits with the acuteness of the angle, until the advantage of increase of pressure gained by making the angle more acute is offset by the increase of friction. Though Joule effect is also present, the hydro-dynamic pressure dueto electrodynamic motor effect is dominant.

The hotter metal is driven out along-the outer sides of channels 27 and 28, as indicated by the arrows, Fig. 3 and is replaced by a flow of metal from the pool passing along the inner sides of the same channel sections, heating the pool by the additional heat of the hotter metal withdrawn and stir ring the pool by the flow, with a resultant 'interming ing of the hotter metal with that of the pool and gradual andnearly uniform increase of temperature throughout the pool. A narrow stream of hot metal ejected at considerable speed is much more effective than the same quantity delivered in a larger stream at a lower rate, since the stirring efiect and immediate distribution obtained by the higher speed reduces the amount of mixing which must be accomplished by the slower Joule efiect. The saving in time is quite material and the tem I perature at. any given time is much more uniform.

The size and shape of the channel are determinedprimarily by electrical considera tlons to obtain a suitable power factor in tional height in that the action at the corner 1 is extended through a greater range. In a brass -furnace havingthe channel beneath.

the pool,- a pouring heat of over-200' pounds, I thousand amperes, excellent results were ob and a secondary current of seven or eight tained with a channel having a length in each leg ofapproximately 18 inches and a cross section of about x3 inches.

Two great advantages arise from this use of motor effect. At'any two points considered along the length of either branch of 'the channel, the pressure is always greater at the point nearer the angle, resulting in a continuity of outflowing stream which would be diflicult to attain otherwise and prevent and would reduce the outer flow of heated metal. In .all of the figures I have therefore shown the innercontour of the channel where it joins the pool, as rounded at 39, but have shown several contours of the outer side of the pool. Thus, in Figs. 2 and 5 the entire channel curves at the end, givin a rounded outer contour at 4:0, and directing the two streams of hot metal toward each other in the pool, as indicated by the arrows, whereas, in Fig.- 7, the outer wall of the channel merges into the wall of the pool, as at 41. This provides a more sharply defined flow of hot metal into the pool in Figs. 2 and 5 and gives quicker diffusion of the heated metal and lower fluid friction of the cooler metal flowing into the channel in 5T1 operation, the metal, unless it be a soft metal, such as lead of relatively low melting point, is melted before it is poured into the pool, the current is then turned on and hot metal from the channel is forced out into the pool with interchange of cooler metal from the pool. 'Additional metal may be added from time to time and reduction from. ores may be efiected, as in other electric furnaces.

In the form shown in Fig. l, I have preferred to place the pouring spout on the right hand side because with the spout at the left, the channel construction. would occupy the place where the ingot or other molds should be located, requiring that these molds be put in place after tilting of the furnace had begun, an undesirable, but not prohibitive arrangement. With the'spout upon the right, as shown, pouring causes interruption of the circuit of the secondary, making it very desirable to interrupt the primary current of the transformer before the molten secondary is interrupted by pouring.

My invention is desirable for use with brass, steel and other metals having rela= tively high melting point, but can be used with lead and its alloys for tempering, refining, etc.

In the form shown in Figs. 5 and 6, the cross section is nearly the same as that of Fig. 1, but a different form of transformer 29 is used. InFigs. 5, 6, 7 and 8 the pool and channel are intended to have the same fluid level, and the channels are shown as open at the tops. I have not considered it necessary to show covers for the pool and channel as these are well known in the art and will differ with the needs of intended use.

In Figs. 5 and 6 I have shown the spout as located at the end and the trunnions at the sides. Here, again, tilting to pour from the spout at the right will reduce the section of the secondary circuit in the channel or break it. Notwithstanding this dangeiz, itis preferable to pour at this side rather than from the corner 36, which would result in dross and other impurities flowing down into the channel. Pouring from the corner or angle 36 is also objectionable, unless the primary current be in the meantime interrupted, for the reason that there would be an opposing flow of molten metal due to the motor effect, and because of the small cross section of the channel.

In the forms shown in Figs. a, 5, 6 and 9, I use a material for the channel walls 22, 43, which is a conductor of electricity of the first class, in order hat the se current may be carried by it and the secondary circuit is" asonably complete 9 a 7 z v. the one. -ol 1165.

Preferably the walls of the pool are made of the same material as those of the channel, giving advantages in construction as well as in completion of the electric circuit independently of the material of the pool. Where the walls of the channel at their ends are connected by a wall which is also a conductor, the secondary is completed even when the channel is empty.

It will be evident that a conductor of the first class may be used for furnaces having a great variety of shapes including all of those shown in the present application, and that it will possess advantages for handling materials which themselves form poor secondaries, and will be particularly useful in maintaining baths for tempering purposes.

In the form shown in Figs. 7 and 8 the construction resembles that of Figs. 1 to 4 in the use of an outer metallic casing and nonconducting lining, but otherwise more nearly resembles the form of Figs. 5 and 6 in the use of single transformers 29 and an equal level of molten metal in the pool and channels. The channels, however, are two in number, 11, 11' and are shown as located at opposite ends of the pool. The trunnions are located at the ends of the channels and the spout at the side of the pool. In this form, the channel wall is substantially tangent with the interior wall of the pool at the point of entry, 44, giving a slight di-ifusion of hotter metal at this point before the body of the pool has been reached and giving also a wider opening for cooler ingoing fluid which reduces the fluid friction and cross currents of fluid flow at this point.

In theform shown in Fig. 9, a conductor of the first class is used for the channel and pool walls, but the channel 11 lies in substantially vertical planes directly beneath the pool, resembling in this the construction shown in Figs. 1 and 2 of the application from which this is divided.

t will be understood that all of the forms are capable of being cooled by air blast, as

' indicated in the first form shown, or by other means already mown in the It will be evident that the character of material used for the conductor of the first class the walls of t .e channel and pool will depend upon the type of construction used and upon. the characteristics of the molten to be handled and particulg if J. vil

bination with a transformer inducing cur-.

rent in the channel content as a secondary and causing outwardflow of content into the pool from each channel toward the other, by reason of motor drive.

2. In-an induction furnace, a adapted to contain a pool, walls forming a closed channel connected with the pool at both ends well below the normal surface of the pool and having at the point of connection well-defined converging directions inconibination with a transformer inducing flow in the channel content as a secondary.

3. In an induction furnace, a furnace body containing a pool in combination with walls forming a channel connected at both ends with the pool, said walls comprising an electric conductor of the first class, in combination with a transformer inducing current in the channel walls and channel content as secondary.

. 4. In an induction furnace, a furnace bod containing a pool in combination with wal s forming a channel connected at both ends with the pool, said walls having an acuteangled bend at a distance from the furnace and comprising an electr'icconductor of the first class, in combination with a transformer inducing current in the channel walls and channel content as secondary.

5. In an induction furnace, a furnace body containing a pool in combination with walls forming a channel connected at both ends with the pool, said walls having an acuteangled bend at a distance from the furnace and obtuse-angled at the connection with furnace body ducing current in the channel walls and channel content as a secondary.

7. The method of heating the content of a furnace pool which consists in providing a molten conductor outside of the pool connecting therewith 'by converging conductor terminals, forming an acute-angled bend in the conductor ata distance from the pool and inducing a current of electricity in the conductor to cause metal heated by the induced current to be also ejected from the channel ends by its action, passing out along the outer sides of the channel, the flow from the two channel ends converging;1 p

8. The method of heating a rnace pool which consists in providin a molten conductor connected with the pool at both ends and in contact longitudinally with a solid electric conductor of the first class and inducing a current of electricity in the molten conductor and solid conductor to heat both of them and cause circulation of the molten conductor into the ool.

9. The method of heating a furnace pool which consists in providing a solid conductor of electricity of tubular form terminating at both ends and a molten conductor occupying the space in the solid conductor and connecting with the pool and simultaneously heating both conductors and causing movement of the molten conductor by passing a current of electricity through the length of both conductors.

JAMES R. WYATT.

Witnesses:

J. LUTHERIA KAUFFMAN, WM. S'rmm. JACKSON.

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