US2883721A - Furnace construction - Google Patents

Description

April 28, 1959l w. H. GORGA ET AL 2,883,721

FURNACE CONSTRUCTION Filed Dec. 27, 1956 3 Sheets-Sheet 1 w, uw ,UPL S www m Y m WHWH. m 4 ImLsFaq w J.; www e y m M O I mw 4w 5M 2 l 4% f n 4 7 .s w M ,M u WQAP .m\ a 1 .l 11V 1111111111111 .il l1 J ||||l (lxnlul FMH l I l l l I I I I I l l I i I l l I I I l I l I l I l l I l l l I I I I Il n ,133 @j im@ y V 7 n April. 28, 1959 w. H. GORGA ETAL FURNACE CONSTRUCTION I5 Sheets-Sheet 2 Filed Dec. 27, 1956 INVENTURS WLLmH. G0

29m Ea/rL WYos, Clad/riesig. Ubel' w zgan@ Eoron new@ ATTORNEYS April 28, 1959 w. H. GORGA ETAL FURNACE CONSTRUCTION 3 Sheets-Sheetv 3 Filed Deo. 27, 1956 JNVENToRs v WlMIa/IILIL G0 Ewrz w. Y0 12, zwrLesII. 027er Eugeneimjon g/zew ATTRNEYS United States Patent Ohio, assignors `to Mallory-Sharon Titanium Corporation, Niles, Ohio, a corporation of Delaware Application December 27, 1956, Serial No. 630,871

Claims. (Cl. 22e-57.2)

u `The invention relates to furnace construction and'more particularly to non-consumable and consumable electrode arc melting furnaces adapted forproducing long titanium mgots.

The manufacture of productsr from titanium or titanium alloys requires the production of titaniumV or its alloys in the wrought form, andthe wrought form in turn must be rolled or forged from an ingot or billet;

*Therey are various methods of producing ingots from titanium sponge. One method of producing suchingots is to melt commercially pure titanium sponge in anonconsumable electrode arc melting furnace.

Another method of ingot production is tomelta consumable titanium electrode in an arc melting furnace.

Certain problems, however, have arisen from'1 the use of such furnaces. The power requirements of these furnaces are usually quite large and therefore require an efiicient means of supplying power to the ingot which serves as one of the electrodes. In prior furnaces, this has been accomplished by a pair of spaced power Acontact guide rolls positioned to engage the outerv periphery of the ingot as it emerges from open endedfmold shell walls.

It is only possible when using such rolls to obtainV line contact between the rolls and the in'got. The surface of the inget, however, is usually somewhat uneven, which reduces the total area of roll-to-ingot contact, itself quite small. rIhus, a very high current density is present at the rollito-ingoia contact when the desired arc voltage and arnperage conditions are obtained.

With such high current density, arcing may occur between areas on the ingot 'and areas on the contact rolls which are not in contact with one another. This arcing may cause pitting of the'surface of theV ingot resulting in a defective surface which may be more uneven thanl the original cast surface. Such surfaceVl conditions are a deiin ite disadvantage, as additional surfacepreparation may be requiredl to provide the lingot with proper surface'conditions for rolling or forging. l y

It is desirable in are furnaces to begin melting at full power. Furnace constructions whichl utilize the bottom of the mold as one electrode necessitate starting the rnelting operation at low power; This lou/"power operation must be continued untila pool ofmolte'n metal isfo'rmed It is a further object of the invention 'to' providev a.Y

closed furnaceN construction with'i iiigtl "power oitct 2,883,721' Patented Apr. 28', 1959 ICC which is rigidly connected to the ingot, yet which is easilyv detachable.

It is also an object of the present invention to provide a closed furnace construction in which the surfaceA of the" mgot produced requires minimum surface preparation,l

produced is substantially longer than the length of the' furnace mold shell walls.

lt is also an object of the present invention to provide a closed furnace construction in which the ingot that is longer than the mold shell is molded and solidified and cooled in an inert atmosphere.

It is a further object of the present invention to pro` vide a closed furnace constiuction in which the' ingotv4 may be stripped from the mold with minimum time loss.

These and other objects apparent to those skilled in the alt may be obtained by the parts, constructions, arrangements combinations and subcombinations compris# ing the present invention, the nature of which is set forth in the following general statement, a preferred embodiment of whichillustrative 'of the best mode in which applicants have contemplated applying the principles-'4' are set forth in the following description and illustrated in the accompany-ing drawings and which are particularly and distinctly pointed out and Set forth in the appended claims forming a part hereof.

In general terms the furnace construction comprising the present invention, may be stated as Iincluding arnold surrounded by cooling means. sur-rounded by an outer shell which is telescopically movable vertically to provide an enclosure which is substantially longer than the mold.

Shell bottom means are detachably mounted 0n the lower end of the outer shell sealed thereto by sealing means. The shell bottom means also includes power attachment means, ingot engaging means, insulating means, and means for moving the outer shell vertically of the mold.

A hopper and hopper feed means are provided at the upper end of the mold. An electrode is rotatably mounted extending through the upper end of thev hopper and along the longitudinal axis of the mold. The electrode, along with being rotatable, is vertically movable.

By way of example, a preferred embodiment ofk then improved furnace construction, showing the best modev in which applicants haveV contemplated practicing the invention is illustrated in the accompanying drawings form;- ing part hereof, wherein similar reference characters indicate similar parts throughout the several views, and in which: Y

Fig. l is a vertical cross section of the improved furnace construction showing the outer shell in its uppermost position and the electrode in its lowermost position;

Fig. 2 is la vertical cross section showing the outer shelll Vin its lowermost position and the electrode in its uppermost position; Y

Fig. 3 is a horizontal cross sectional view taken along the line 3 3, Fig. 1; n n

Fig. 4 is a horizontal cross sectional View taken on the line 4 4, Fig. 1; n Y n Y Fig. 5 is a vertical sectional view showing the coolant ow, taken on the line 5--5, Fig. 3;

Fig. 6 is an enlarged fragmentary sectional view' showing the sealing means at the bottom of the outei` shell; and,

ing the sealing means at the top of the outer shell;

The cooling means is` Referring more particularly to the construction illustrated in the accompanying drawings, the furnace construction comprising the present invention is indicated generally at and includes a furnace charging hopper 11, a furnace bottom 12, and an electrode generally indicated at 13.

The furnace 10 also includes an inner mold shell 14 surrounded by a mold water jacket or coolant shell 15. An annular ring 16 is welded completely around its periphery on its inside edge to the bottom of the inner mold shell 14 and on its outside edge to the coolant shell 15. The inner mold shell 14 and the mold water jacket 15 are also welded at their upper ends to an annular flange 17 thereby providing a coolant chamber.

The furnace charging hopper 11 includes a hopper bottom flange 18 bolted to flange 17 by bolts 18a and sealed by O-ring 18b to flange 17. Flange 18 is also welded to inner tapered hopper side wall 19, and outer tapered hopper side wall 20. The space formed between the tapered hopper walls 19 and 20 and the bottom face 26a of the hopper `top flange 26 and the upper face 18e of the hopper bottom ange 18 provides chamber means for cooling the hopper. Water or any other suitable coolant may be introduced through any convenient inlet and outlet pipes (not shown).

A hopper feed inlet tube 21 provided with screw conveyor feed means 22 is connected to a hopper feed inlet opening 23. This connection -may be formed by any suitable means, for example, as shown in the drawings, by a flanged coupling 24 secured with bolts 25. The feed inlet opening 23 is integral with the tapered hopper side walls 19 and 20, and is sealed at the flanged coupling for example with O-rings 27.

The furnace charging hopper 11 further includes a hopper top ange 26 secured preferably by welding to the top ends of the tapered hopper side walls 19 and 20.

The furnace charging hopper 11 is closed at the top by a hopper top wall 28, which is secured to the hopper top ange 26 by bolts 29. A top plate 30 is preferably welded to the hopper top wall 29, and is provided with a recess 30-a formed in the bottom face 30-b thereof.

A chamber 30-c is thus formed by the recess 30-a and the hopper top wall 28 thereby providing a means for cooling the upper end of the hopper 11.

The inner mold shell 14 and the coolant shell 15 are surrounded by an outer shell wall 31 which is telescopically movable axially with respect to said inner mold' shell 14 and coolant shell 15. The outer shell Wall 31 is 'provided with an upper sealing means 32, as shown in Fig. 7.

The upper sealing means 32 includes a ange 33, preferably welded to the top of the outer shell wall 31, and an annular ring 34. The annular ring 34 is secured to the ange 33 and thereby to the outer shell wall 31 by 'bolts 35. The coupling or joint between the annular ring 34 and the ange 33 is sealed by a sealing ring 36. The annular ring 34 is provided with grooves 37 which receive O-rings 38, thereby permitting an air tight sliding fit between the annular ring 34 and the coolant shell 15.

A gas inlet valve 39 is provided at the lower portion of the outer shell wall 31. This permits the space formed between the outer shell wall 31 and the coolant shell 15 to be evacuated or filled with an inert gas.

The furnace bottom 12 includes a lower ange ring 40, a power plate 41, bottom support member 42 and an ingot engaging member 43.

The lower ange ring 40 is preferably welded to the bottom end of the outer shell wall 31. The power plate 41 and the bottom support member 42 are secured to the lower ange ring 40 by bolts 44. The power plate 41, bolts 44, and bottom support member are electrically insulated from the lower ange 40 and the outer shell wall 31 by an insulation ring 45, and insulation collars 46.

The bottom support member 42 is provided with a circular recess `47 in the upper face 48 thereof. `The recess 47 and power plate 41 form a chamber 49. A coolant such as water may be introduced into the chamber 49 through inlet pipe 50 and discharged through outlet pipe 51, said pipes extending through the bottom face 52 of the bottom support member 42, and into the chamber 49.

An elevator shaft receiver 53 is secured to the bottom of the bottom support member 42 by bolts 54. The shaft 55 is detachably secured to the receiver 53, for example, by threads 56. The elevator shaft 55 is connected to any suitable lift means (not shown) adapted to provide vertical movement, such for example as a hydraulic jack.

Bottom insulation 53-a and insulation collars 53h insulate the receiver 53 and the lift shaft 55 from the bottom support member 42 and power plate 41.

Preferably diametrically opposite power lugs 57 are connected to the outer periphery of the power plate 41. Connected to the power lugs 57 are a pair of water cooled power connection members 58, which are integral with the power lead lines 59. This connection may be provided by any convenient means, for example, as shown in Figs. 1 and 7, by bolts 60 and nuts 61.

In order to cool the power connection members 58, water or any other suitable coolant flows through the power lead lines 59, which are provided with a water passage (not shown), into the hollow interior (not shown), of the power connection members 58 and nally out coolant outlets 62.

Power plate 41, bottom support member 42, and insulation ring 45 are provided with grooves 63, 64, and 65 respectively, which respectively receive rings 66, 67 and 68. The O- rings 66, 67 and 68 are used to insure an air tight joint between the lower ange ring 40, the insulation ring 45, the power plate 41 and the bottom support member 42.

The ingot engaging member 43 is preferably welded to the power plate 41, and is cup shaped so that it may receive and clamp the end of a stub ingot 69. The lower end of stub ingot 69 may be machined so that it aiords good electrical contact with the upper face 70 of the ingot engaging member 43. The ingot engaging member is provided with a series of circumferentially spaced set screws 85 which provides a convenient method of securing the stub ingot 69 to the ingot engaging member 43, and which may be easily and speedily detached.

The electrode 13 is of the usual vtype used in nonconsumable electrode arc furnaces, and includes a tip 71 which is preferably made of tungsten. The tip 71 1s secured to an angled shaft 72 which is in turn secured to the main electrode shaft 73. The electrode 13 is 4supported above the furnace by an electrode support 74 which is provided with bearings 75. The electrode 13 is rotatable about its longitudinal axis, and is also vertically movable; and the electrode is insulated from the hopper top plate 30 by the insulation collar 76 which is fastened to the hopper top plate 30 by bolts 77.

The main electrode shaft 73 may be hollow so as to provide cooling means for the electrode 13.

The molding portion of the furnace is cooled by the introduction of a coolant 78 into the space 78a formed between the inner mold shell 14 and the coolant shell 15. The coolant 78 enters .through the inlet pipe 79 and is directed to the bottom of the space 78a by a U-shaped channel 80 forming a passage.

Coolant 78 lls the space 78a and is discharged therefrom through outlet pipe 81. The direction of ow of the coolant 78 may be seen by the arrows in Fig. 5.

The furnace is operated by securing the stub of a previous ingot 69 to the engaging member 43. The furnace bottom 12 is then assembled to the position shown in Fig. 1 of the drawings.

An arc: is then struck between the ingot 69 and the electrode tip 71,. Metal of. a` siutable size is'fed into the is moved downward. At the end of a melt the' o uterv shell wall 31 is in its lowermos't vertical position and the electrode 13 is in its uppermostjvertical position. This nal position is shown in Fig. 2 where the ingot 6 9 is illustrated as approximately twice the length of the mold 82'.

Duringv the operation of the furnace the movement' of the outer shell wall 31 is limited at its lower most position by engagement of ring 34 with stop ring 83 (Fig. 2) which is secured to annular ring 1d,k and at its upper most position by engagement of ring 34 with stops 84 which are circumferentially spaced around coolant shell 15, and welded thereto.

The gas inlet valve 39` also providesa means for purging the'space between ingot 69, and outer shell wall 31 when said outer shell wall'31' is in-its lowermost position.

From one fundamental aspect, the improved furnace construction includes an open-ended stationary cylinderlike mold and an associated movable piston-like closure; and the piston-like closure has an outer shell telescopically enclosing the cylinder-like mold and has engaging means for mounting and electrically connecting the ingot being formed for telescopic movement within the cylinderlike mold.

In the improved construction, all of the walls for the hopper, its upper closure, the cylinder-like mold, and the ingot-engaging portion of the piston-like closure are provided with means for cooling such walls with any suitable coolant, such as water.

Furthermore, the various connections between the stationary and movable furnace parts are sealed in an airtight manner so as to provide a hermetically sealed chamber in which titanium may be efciently melted despite electrode movement within the chamber and withdrawal of the ingot from the cylinder-like mold as it is being formed.

In addition, the improved construction enables the use of a stub ingot in starting a heat which performs a number of important functions. First, the stub ingot fixed to the support and power supply closure member of the piston-like closure enables a heat to be started at full power.

Second, the stub ingot fixed to the support and power supply member provides ecient means for supplying electric power for the melting arc directly to the arc and to the pool of molten metal melted by the arc.

Finally, the stub ingot fixed to the support and power supply member enables the necessary force to be applied to the ingot as it is being formed for withdrawing it from the cylinder-like mold thereby enabling the production of a relatively long ingot within substantially shorter mold side walls, in which the elongated formed ingot has relatively smooth surfaces on its sides and lower end.

The invention provides a construction in which there is an efficient power contact arrangement between the power supply and the ingot, in which the eicient power contact is easily and speedily detachable, in which the produced ingot requires a minimum of surface preparation, in which the ingot is cooled in an inert atmosphere, in which the ingot is readily removed from the furnace, and in which an ingot substantially longer than the mold wall may be produced.

Thus, the furnace construction comprising the present invention overcomes the above-stated difficulties and prob- 6.l lems of prior constructions andi meets the necessary-requirements;

In the foregoing description certain terms have been used for brevity, clearncss. and understanding, but no unnecessary limitations have been implied therefrom as such words are used for descriptive purposes and are intended to be broadly construed.

Moreover, the embodiment of the improved construction illustrated and described herein is by way of example and the scope of the presentV invention is not limited to the exact construction shown.

Havingnow described,A the invention, construction, operation and use of a preferred" embodiment thereof and the advantageous new and useful results obtained thereby; the new and useful furnace construction and reasonable mechanical equivalents thereof obvious to those skilled in the art are set forth in the appended claims.

We claim:

l. Furnace construction including a fluid-cooled, tubular-,walled mo1d, ,closure means for the upper end of the mold, material feed means communicating with the upper end of the mold, axially movable electrode means extending through said closure means and into said mold; bottom closure means for the lower end of the mold including a bottom uniti, and a tubular shell connected to the bottom unit and telescopically surrounding and axially movable with respect to said mold with a telescopic joint therebetween, means for sealing =said"telescopic joint in a fluidtight manner; means for moving the bottom closure means axially of the mold in either direction, ingot-engaging means on the bottom unit below the mold, means for supplying power to said electrode and said ingot-engaging means, and the interior of the mold and bottom unit thereby being sealed in a fluid-tight manner from the atmosphere.

2. Furnace construction including a tubular-walled mold, closure means for the upper end of the mold, material feed means communicating with the upper end of the mold, axially movable electrode means extending through said closure means and into the mold, bottom closure means for the lower end of the mold including a bottom unit and a tubular shell connected to the bottom unit and telescopically surrounding and axially movable with respect to said mold with a telescopic joint therebetween, means for sealin g said telescopic joint in a fluid-tight manner; means for moving the bottom closure means axially of the mold in either direction, ingot-engaging means on the bottom unit below the mold; means for cooling the mold, upper end closure means, electrode means, ingotengaging means, means for supplying power to said electrode and said ingot engaging means, and the interior of the mold and bottom unit thereby being sealed in a tluidtight manner from the atmosphere.

3. Furnace construction including a fluid-cooled tubular-walled mold, closure means connected with the upper end of the mold, means for sealing the connection between the mold and upper end closure means, material feed means communicating with the upper end of the mold, axially movable electrode means extending through said closure means and into said mold; bottom closure means for the lower end of the mold including a bottom unit, a tubular shell comiected to the bottom unit telescopically surrounding and axially movable with respect to said mold with a telescopic joint therebetween, means for sealing said telescopic joint in a Huid-tight manner; means for sealing the connection between the bottom unit and tubular shell; means for moving the bottom closure means axially of the mold in either direction, the bottom unit including a power supply member and a mold-engaging member mounted on the power supply member below the mold, said movi-ng means including a support member connected to the power supply member, the support and power supply members having walls forming a cooling chamber for the power supply member, sealing means for the connection between the support and power supply members, and the interior of the mold and bottom unit thereby being sealed in a Huid-tight manner from the at-v mosphere. l l

4. Furnace construction including a huid-cooled tubular-walled mold, closure means for the upper end of the mold, material feed means communicating with the upper end of the mold, axially movable electrode means extending through said closure means and into said mold, bottom closure mea-ns for the lower end of the mold including a bottom unit and a tubular shell, ingot-engaging means on the bottom unit below the mold, power supply means connected to the'bottom unit, the tubular shell telescopically surrounding and being movable axially with respect to the mold with Ia telescopic joint therebetween, means for sealing said telescopic joint in auid-tight manner, means for moving the bottom closure means axially of the mold in either direction to alter the telescopic arrangement of the shell with respect to the mold, the shell and mold being provided with stop means limiting relative telescopic movement of the shell and mold in either direction, and the interior of the mold and bottom unit thereby being sealed in a fluid-tight manner from the atmosphere. v

5. Furnace construction including a tubular-Walled mold, closure means connected with the upper end of the mold, means for sealing the connection between the mold and upper end closure means, material feed means communicating with the upper end of the mold, axially movable electrode means extending through said closure means and into the` mold, -bottom closure means for the lower end of the mold including a vbottom unit and a tubular shell connected to the bottom unit, means for sealing the connection between the bottom uni-t and tubular shell; means for cooling the mold, upper end closure means, electrode means and bottom unit; the tubular shell telescopically,surrounding and being movable axially with respect to the mold with a telescopic joint therebetween, means for sealing the telescopic joint in a uid-tight manner, the bottom unit including an ingot-engaging member below the mold, means for clamping a portion of an ingot to the ingot-engaging member, an ingot-arc power supply member connected to the ingot-engaging member, 'a support member connected to the power supply member, elevator means connected to the support member for moving the bottom closure means axially of the mold in either direction, stop means limiting relative axial movement between the mold and shell, and the interior of the mold and bottom unit thereby being sealed in a fluid-tight manner from the atmosphere.

References Cited in the le of this patent UNITED STATES PATENTS 803,147 Appleby Oct. 31, 1905 1,498,582 Soderberg June 24, 1924 l 2,541,764 Herres et al Feb. 13, 1951 2,763,903 Herres et al Sept. 25, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,883,721 April 28, 195e William H. Gorga, et el It is hereby certified that error appears in the above numbered patent requiring correction ,and that the said Letters Patent should reed as orree'te'd belowf,

in the' grant; lines Q 4 and 13, and in the heading of' the printed /7 specification, lines. 5 and o, name oi` assignee, ior "Mallory-Sharon Titanium Corporation", each occurrence, reed Mallory-Sharon Metele Signed end vsealed this 8th dey oi September 195% (SEAL) Attest:

KARL H., AXLINE v Y ROBERT C WATSON ttestlng Offlcer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 2,883,72l April 28, 1959 william E. Gorga, et a1 t error appears. in the above numbered Itis hereby Certified the patent requiring correction ,and that the said Letters Patent should read as eorreo'te'd below.l

In the grant; linee 3, z, and i3, and in the heading of the printed specification, lines. 5 and 6,v neme oi' assignee, for "Mallory-Sharon Titanium Corporation, each. ,oeeurrene/e,` read Mallory-Sharon Metals Corporation Signed and .sealed thisy '8th day of September 19.59

(SEAL) Attest:

KARL H. AXLINE Y ROBERT C WATSON A ttes'blng Officer Comuissioner of Patents

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