US1235628A - Lateral-channel induction-furnace. - Google Patents

Description

3. R. WYATT.

LATERAL CHANNEL moucno N FURNACE.

APPLICATION FILED JULY 19. 916.

-SHEET 1.

PaiQnted Aug:

2 SHEETS albums/1 APPLICATION FILED JULY 19.1916.

Patented Aug: 7/, 191?.

2 SHEETS-SHEET 2.

Elwuemtoz UNITED STATES JAMES R. WYATT, 0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO TI-IE METAL CQMPANY, INCORPORATED, OF EHILADELPHIA, PENNSYLVAN PORATION 0F PENNSYLVANIA.

LATERAL-CHANNEL I aces:

con-

To all whom it may concern:

Be it known that T, JAMES R. WYATT, a citizen of the United States, residing at 2024 S. 21st street, Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a certain new and useful Lateral Channel Induction Furnace, of which the following is a specification.

The purpose of my invention is to stir a furnace pool by whirls of heated metal, driven by means of an electric current flowing through a molten channel content, and meeting the pool in substantially horizontal planes well below the surface of the pool.

A further purpose of my invention is to stir a pool by general horizontal scouring effect of a hot metal flow driven into the pool preferably near its circumference by motor efiect and which may be introduced in a direction generally tangential thereto.

T have preferred to illustrate my invention by but a few of the many forms in which it may appear, selecting therefor forms which are practical and eiiicient and which at the same time well illustrate the principles of my invention.

Figure l is a side elevation of one form of my invention.

Fig. 2 is a fragmentary section upon line 2 2 of Fig. i

Fig. 3 is a section upon line 33 of Fig. 1 broken away in part.

Fig. i is a fragmentary horizontal section of a modification and upon an enlarged scale.

Fig. 5 is a top plan view, partly broken away, showing a further modification of the construction shown in Fig. 1.

Fig. 6 is a top plan view, partly broken away, of a further modification of the construction shown in Fig. 1.

Fig. 7 is a side elevation of afurther modification.

Fig. 8 is a top plan view of a two-phase, two channel furnace.

Figs. 9 and 10 are a top plan and section upon line l0l0 thereof showing a channel and pool having the same fluid level.

In the drawings similar numerals of reference indicate like parts.

My invention is of general application to reduction, refining and re-melting of metals and treatmentof their alloys and has been found to be particularly adapted for re" melting chips, shavings, turnings and small Specification of Letters Patent.

Patented Aug. '3, 19" Serial No. 110,202.

pieces of brass and other alloys which have presented difiiculty to foundrymen because of the smallness of the pieces of metal and he presence of metals having a vaporizing point below the melting point of the alloys.

it is necessary in these to superheat the alloy several hundred degrees above its melting point, in order to pour good castings or salable ingots. The heat losses, vaporization of metals, change of composition of the alloy and other injury to the resultant metal have previously been serious and the cost prohibitive.

This application is a division in part, plus additional matter. of my application for patent for induction furnace, filed January 2%, 1916, Serial No. 73,810.

in Figs. 13, I have shown an electric furnace having in general a body 11 and channel portion 12 connected therewith, inclosing a transformer 13 between. These with the closure for the body are adapted to be rotated about trunnions in any suitable bearings by a worm wheel and other mechanism so well known that I have not considered it necessary to illustrate them. The channel is interrupted by any suitable joint as at 15 to permit insertion and removal of the transformer where it is desired to avoid tie removal of a purpose and to break the electrical continuity of the casing, preventing it from carrying secondary current.

The furnace body, adapted pool of molten metal and melt metal down into it, is jacket 16, lined at 17 and carrying a pouring spout 18. The upper portion of the body is partly closed by annular tile 19 held in a shell 20 and having a conical opening in the annulus in which a plug 21 carried by a cover 22, which may be hinged at 23. The shell may be secured to the jacket by ears 2% and bolts 25.

in this construction 1' prefer to connect the casing 28 within which the channel is formed directly with the body of the furnace as by joint as at 27 which also tends to reduce the flow of secondary current in the casing.

The transformer is intended to be shown as of single phase shell type having laminated magnetic circuit comprising a single central leg 28 and end legs 29 and 30, the windings 31 and 32 being in this case loto receive a the pieces of made up or an outer transformer leg for this 1 nace jacket about forms defining the channel and pool. These forms are preferably separated along the line of the junction between the casing and jacket, in order that the casing may be advantageously filled with cementitious lining and the same rammed about the channel form before the form for the pool is put in place.

An asbestos paste insulating compound has been found to be quite desirable. It must be dried out gradually.

4 The channel 34 is flattened in cross section, preferably of rectangular or approximately rectangular shape and -with the Longer dimension of the rectangle parallel with the axis of the middle transformer leg. The channel length is formed with an acute angle at the turn, as at 35, outside of the furnace, with approximately straight channel branches 36, 37 adjoining the angle. At the junction of the branches with the pool acute angles are avoided, the contour being rounded, or at least obtuse angled, where the connections are made with the furnace, a s\ seen in the horizontal sections.

This furnace operates primarily by reason of the tendency of conductors to separate when carrying currents flowing in oppositedirections. The channel branches here meet in an acute angle which greatly accentuates the tendency to separate which causes the hot metal to be ejected along the outer edge of each channel branch with consequent replacing flow of cooler metal along the inner sides of each branch entering the channel ends inside of, but quite close to the path of ejected hotter metal. In tests made this operation was evident, not only by reason of the observed currents of flow, but because of difierences in temperature found to exist, the time of chilling of the several lines of flow and the contour of the surface when chilled.

The test was performed in an open channel and pool. The obtuse angled connection with the pool portion of the circuit avoids disturbing motor efiect at the junction points between the channel and pool, which, by theory, as well as by tests made, would oppose the flow of fluid from the angle 35 through the branches 36 and 37. The rounding at the junction causes sufficient rounding of current flow at this point to relieve from objectionable motor effect there.

In the tests-made the outlets from the channels to the pool were formed near to the periphery of the pool and there were lines menses In Figs. 3, 6 and 9 the direction of flow from the channel where it meets the pool, is shown as generally parallel to the outer walls of the pool, which with the curved form of pool wall normally used, gives nearly tangential flow at these points of connection at opposite ends of the channel, pro ducing a scouring How of hot metal as will be hereinafter pointed out more fully, at the outer edges of the bottom of the pool where the coolest metal would normally otherwise lie with an inward flow of the cooler metal displaced into the channel ends, closely adjoining the points of hot metal discharge.

In Fig. 4 the directions of flow closely adjoining the channel angle outside of the pool are shown by arrows in which the outward stress of metal from the corner is clearly apparent, avoiding a dead spot at this point where the tendency to overheat would otherwise be greatest.

t will be noted that, in most of the constructions shown, the two ends of the channel meet the pool at substantially the same height and well below the intended level of metal in the pool, but that the scouring efiect of the motor driven flow in intermixing the hotter metal with that of the pool will be similar even if the level of the pool be no higher than that in the channel, as in Figs. 9 and 10. There isan advantage in having the pool depth greater than that of the channel in the increased volume of metal handled andthe larger proportion which the heat bears to the total volume of metal; and in such case it is desirable to have the additional pool depth above the channel entrances rather than below, for the reasons that the hot metal ejected from the channel ends will rise, improving the mixing and therefore the heating of the pool, also because the head upon the channel will main tain uniform channel height, notwithstanding variations in the total quantity of molten metal in the furnace. The hydrostatic head produced also causes the cooler metal to flow in more rapidly along .the inner channel walls to take the place of that fed out from the channels by reason of motor In all of the forms shown the direction of discharge from the channel into the pool is substantially horizontal.

In all of the forms it will be further noted that the provision for pouring withdraws metal from the pool, as distinguished from loll withdrawing it from the channel,- avoiding .ends which would result from any extended offshoots from the channel for pouring purposes but untraversed by the electric current.

It will be evident that the direction of introduction of motor-driven hot metal flow will be determined somewhat by the size and shape of the pool, and character of material handled, as well as by the individual preferences of the designer, substantially tangential delivery of the hot metal discharged being more desirable for smaller furnace bodies, while larger pools or the shape of the pool in cross section may render it desirable to discharge in a direction departing considerably from the tangent toward the center of the pool, as in Fig. 5.

In the form shown in Fig. 4 l have shown a portion of a channel member 12 comprising a conductor of electricity of the first class, such as steel or copper alloy and forming part of the secondary circuit. The ends of the channel branches and height of pool level are not indicated and might follow any of my forms.

In the form shown in Fig. 5 I have shown a construction in which there is no outer casing, but instead the entire furnace is made of one homogeneous resistant material, a conductor of electricity of the second class, such as plumbago. There are two channels 12 on the same side of the body 11. The transformer 13 has but two legs and surrounds but one side of each channel. The metal discharges into the pool at a considerable angle with the tangent to the pool wall.

For. some of the purposes of my invention, it will be obvious that the direction of the plane in which the channel lies need not be horizontal, but can slope therefrom, and still come within the scope planned for this application provided the channel be mainly outside of the vertical line of the furnace, corresponding to the line of demarcation in that particular made between this case and the co-pending application from which this has been taken.

The position of the pouring spout on the side shown in Figs. 1 and 6, for example, is not of primal importance. There is a slight advantage in having the spout upon the same side as the channel in that a larger proportion of the furnace content can be poured at a heat without breaking the continuity of the secondary electric circuit, but there is also a considerable disadvantage in that it interferes with the positioning of the ingot molds into which the furnace is to pour, requiring that these be moved to position after tilting of the furnace has begun.

in the form shown in Fig. 6 a lined metallic casing is shown with two channels at the side of the casing. Adjoining branches of these two channels 12 are united at 38 in a common shorter (1 to 1.4) branch whose lower resistance well fits the construction for two-phase operation with transformer 13 for each phase. The lines of conductor of the first class in order that metallic flow in not be as clear and distinct as in the outer channel branches.

In Fig. 7 the same general structure as in Fig. 5 is shown except that the material is a conductor of the first class and the channel member 12 slopes slightly, though located entirely outside of the vertical lines of the walls of the furnace body 11 In the form shown in Fig. 8 two channel members 12 are shown with separate transformers 13, one about each channel and preferably one on each phase of a two-phase circuit. 1 illustrate a lined metallic casing having the spout at the side of the pool and the trunnions at the ends. The pool is preferably at the same fluid level as the channels and the latter may be open at the top with removable covers if desired.

in the form shown in Figs. 9 and 10, the level 39 of the metal in the pool is the same as that in the channel at 40 and the channel 34: may be opened at the top, as shown. The material of the channel walls 12 and preferably oi the furnace body 11 also is a they may act as more or less complete secondaries for the transformer. This is specially desirable where metal such as lead 41 having a low melting point and poor electric conductivity or other electric characteristics is being melted, as the channel casing forms a conductor for the secondary through which the heating may be edected, melting the base metal initially, if desired, and maintaining it at the heat required for pouring, refining, tempering, or other uses.

In all of my "forms I have preferred to connect the channel ends with the pool the same or nearly the same height; and in some phases of my invention as disclosed herein the operation is dependent for its success and i of the forms of my invention herein best operates with the angle within the channel acute.

Breaking the magnetic circuit in the iron where a casing is used, reduces the losses from stray magnetic field and these losses are further reduced by the greater width than thickness, the cross section the molten secondary.

The greater width than thickness places this secondary in the most advantageous position to pick up a maximum of lines from the transrormer.

It will be evident from the several illustrations which I have given that my invention may be utilized in furnaces which are conductors of either first or second type, or non-conductors, in furnaces which use or lack separate stiffening or protecting support for a crucible or mere lining for metallic casings, in connection with a single channer or with multiple channels and having this common channel will the channels, on the same or on opposite sides where the multiple is. used, and with a variety of transformers and transformer connections and that the outward and inward flow of molten metal from and into each connection of the channel with the pool maybe directed to cotiperate with the particular shape and size of furnace body selected', being arranged tangentially thereto, or; inwardly directed to intermingle the metal heated within the channel with that of the pool to the best advantage.

I have aimed to disclose a flexible motor-effect means of securing circulation and of adapting it to use for the accomplishment of the heating and stirring needs of the designer who may now apply it according to thermodynamic and hydraulic laws to get the best results in each equipment.

The length of the channel and the width and thickness of the same will be dictated by the total resistance which it is desired to have in the secondary path, the width of the pool with which the channel ends are to be connected, the volume of the pool to be stirred, whether the channel ends are to terminate near the extreme sides of the pool or not, the strength of the current, the conductivity and other electrical properties of the metal being handled and various well recognized factors entering into the attainment of a high power factor for the circuit.

The motor edect is advantageous whenever the amperage of current, in proportion to the square of the current, whatever the shape of cross section and nearly the same for given current strength whether the cross *section be small or large. The area of section and its shape are therefore dictated by the desirable width of section to receive the transformer flux and to get aslarge a flux operating at close quarters in the angle as possible, and the requirements that it must be large enough to avoid undue friction, small enough for the flow of molten metal to constitute a jet and that the volume discharged must bear a proper proportion to the total size oi? the pool.

Tn operation, in all of the forms, the molten metal within the channel and that within the connecting pool form a resistor in which the secondary circuit or" the transformer is set up. Except where the ma.- terial of which the channel walls are formed is itself a conductor of electricity, this molten path forms the only complete path of the secondary circuit. The active force of the motor efiect, most intense at the angle, is effective to lessening degrees throughout the entire diverging lengths of the two channel branches 36 and 37, causing a steady flow of hot metal along the outer walls of the two branches which will act as a jet it the cross section. be not excessive. It will cause gradual circulation in larger cross sections. Cooler molten metal flows in along the inner walls of both channel branches in all of these forms to take the place of the hot metal driven out. The inward flow is more rapid where the molten metal of the pool forms a head above the channel.

The angles where the pool and channel connect, it acute, would result in counterflows which are objectionable to a degree varying with the acuteness of the angle. To avoid this, ll make these angles obtuse, as by Lfgurving the inner walls of the channels at As the direction of what might be termed the plane of the channel (2'. 6. through the center line of the channel length) approaches the horizontal, stirring movement because until the Walls have become heated up to the point where they become conductors, when a 1 part of the secondary current flows through these walls. This may be utilized to add to or steady the temperature of the channel content according to the proportions of the parts and conducting capacity of the material utilized. 7

Where the channel wall is a conductor of the first class, in handling lead, solder and other material and alloys having a low melting point, the metal Within the channel and pool will ordinarily not burst the channel walls when cooling, particularly it these channel walls be formed of metal or if the channel be opened at the top. The material from which the wallsare formed would ordinarily. form a better path for the secondary current than these low-melting-point metals; and when the metal has been chilled in the channel and pool, its melting may be expedited by reason of the heating efi'ect oi the secondary current upon the walls.

The current through the walls may be used to maintain the temperature of the melted bath. This has advantages, in that the secondary electrical flux will be nearly constant, even though the height of metal in the bath vary considerably.

In most of the forms shown, I find it elesirable to pour the content of the pool and channel out when the furnace is to be chilled.

mes es line of the furnace body and wholly below the intended working level of molten metal and having its connections with the pool obtuse-angled on-the sides toward the intervening pool and at substantially the same height, in combination with a transformer surrounding the channel, using the molten metal in the channel as its secondary and inducing flow of molten metal by motor effect outwardly from each branch of the channel adjoining the acute angle.

2. In an induction furnace, a furnace body adapted to contain a pool of molten metal,

and walls forming achannel connected at its ends with the pool and acute-angled at approximately the middle of its length, said channel lying mainly outside of the vertical line of the furnace body and wholly below the intended working level of molten metal and having its connections with the pool at substantially the same height, in combination with a transformer surrounding the channel, using the molten metal in the channel as its secondary and inducing flow of molten metal by motor effect outwardly from each branch of the channel adjoining the acute angle. I

3. In an induction furnace, a furnace body having a contour curved in horizontal sections and adapted to contain a pool of molten metal, and walls forming a horizontally disposed closed channel, said channel connecting with the pool at its opposite ends, in proximity to the perimeter of the internal curved wall of the furnace body and having an acute-angled bend outside of the furnace body, in combination with a transformer inducing current in the molten channel content to produce motor effect greatest at the acute angle and cause flow of current outwardly from each channel connection into the 001. I

4. The method of heating the molten pool of a furnace by induced electric currents, which consists in setting up whirls of relatively hotter metal by motor effect, set up outside the pool, entering the pool at two points about the perimeter of the pool in a generally horizontal direction and at substantially the same height, and withdrawing relatively cooler metal from the pool at substantially the same points at which the hotter metal is introduced.

5. The method of heating the molten pool of a furnace by induced electric currents, which consists in setting up whirls of relatively hotter metal by motor effect, set up outside the pool, entering the pool at two points about the perimeter of the pool in a generally horizontal direction and at substantially the same height, relieving from motor effect at the entering points and withdrawing relatively cooler metal from the pool at substantially the same points at which the hotter metal is introduced.

6. The method of heating the molten pool of a furnace by induced currents of electricity which consists in setting up whirls of relatively hotter metal by motor effect, at two points substantially in the periphery of the pool and generally horizontal and tangential to the pool and withdrawing relatively cooler metal flowing out from the pool at approximately the same points.

7. The method of heating the molten pool of a furnace which consists in providing a substantially horizontally disposed molten conductor connected with the pool at two points, forming an acute angle in the conductor at a distance from the pool and inducing a current of electricity throughout the length of the conductor.

8. The method of heating the molten pool of a furnace which consists in providing a substantially horizontally disposed molten conductor connected with the pool at two points, well below the level of the pool, forming an acute angle in the conductor at a distance from the pool, and inducing a current of electricity throughout the length of the conductor.

9. The method of heating the molten pool of a furnace which consists in providing a substantially horizontally disposed molten conductor connected with the pool at two points, forming an acute angle in the conductor at a distance from the pool, forming the inner contour of the conductor as an obtuse angle where it connects with the pool and inducing a current of electricity throughout the length of the conductor.

10. The method of heating the molten pool of a furnace which consists in providing a substantially horizontally disposed molten conductor connected with the pool at two points, well below the level of the pool forming an acute angle in the conductor at a distance from the pool, forming the inner contour of the conductor as an obtuse angle where it connects with the pool and inducing a current 'of electricity throughout the length of the conductor.

11. In an induction furnace, a furnace body, a substantially horizontal, closed channel connected therewith, having its ends connecting with the furnace body well below the surface of the pool and at substantially the same height, a transformer inclosing one branch of the channel and trunnions connected with the furnace about which it may be tilted.

12. In an induction furnace, a body portion adapted to hold molten metal, walls forming a channel containing an acuteangled bend and connected at both ends with the interior of the body portion but lying chiefly outside of the vertical lines through the molten metal and a transformer adapted to utilize the channel content as secondary.

13. In aninduction furnace, a body portion adapted to hold molten metal and to pour from said body portion, Walls forming a channel connecting at both ends with the interior of the body portion and comprising branches united outside the vertical 1e lines of the body portion to form an acute angle and induction means for passing an electric current through the length of the channel content about the acute angle. JAMES R. WYATT. Witnesses:

J. LUTHERIA KAUEFMAN, WM. S'rnnm, JAcKsoN,

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