US3602623A

US3602623A - Consumable electrode furnace

Info

Publication number: US3602623A
Application number: US761893A
Authority: US
Inventors: Patrick J Wooding
Original assignee: Consarc Corp
Current assignee: Consarc Corp
Priority date: 1968-09-16
Filing date: 1968-09-16
Publication date: 1971-08-31
Anticipated expiration: 1988-08-31

Abstract

A consumable electrode furnace for simultaneously producing a plurality of ingots, comprising a single hydraulic ram for reciprocably supporting a plurality of electrodes clamped in parallel depending relation. The furnace further includes a plurality of crucibles which are equal to or greater in number than the number of electrode clamps. The furnace also includes only one regulator and set of instrumentation and the melt rate of the electrodes is self-compensating.

Description

United States Patent 12 Inventor Patrick J. Woodlng 2,2 1s,321 3/1942 Keir 164/52 M omm m -J- 3,240,856 3/1966 Wynne 13/14 [21] Appl. No. 761,893 3,024,352 3/1962 Danhier.... 219/126 [22] Filed Sept. 16,1968 3,139,473 6/1964 Morris 13/13 [45] Patented Aug.3l, 1971 2,668,183 2/1'954 Foyn 13/ 16 [73] Assignee Cons'arc Corporation 2,700,692 l/1955 Carleton,Jr.. 13/16 Ra'ncoeas, NJ. 2,783,411 2/1957 Matulaitis..'... 314/69 Continuation olapplleation Ser. No. 3,152,372 10/1964 Hopkins 164/52 617,228, Feb. 20, 1967, now abandoned. 3,190,949 6/1965 Gruberet al... 13/31 I 3,234,608 2/1966 Peras. 164/52 FOREIGN PATENTS 979,583 1/1965 Great Britain 164/52 [54] CONSUMABLE ELECTRODE FURNACE Primary Examiner-Bernard A. Gillieany l 10 Claims, 5 Drawing Flgs. Assirtan! Examiner- R. N. Envall, Jr. [52] Us. 3,14, Attorney-Seidel, Gonda 8z Goldharnmer 13/13 is f 34/60 ABSTRACT: A consumable electrode furnace for simultanel 0 Search u. on p d i g a of ingot comprising a single 13/31- 13; 75/10 hydraulic rarn for reciprocab ly supporting a plurality of elec- 919/ trodes clamped in parallel depending relation. The furnace 56 further includes a plurality of crucibles which are equal to or I 1 Rem-mm cm greater in number than the number of electrode clamps. The UNITED STATES PATENTS furnace also includes only one regulator and set of instrumen- J J 3 6/1964 Cooper .L, 13/9 tatlon and the melt rate of the electrodes is self-compensating.

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PATENlEnaussnsn 3.602.623

' sumanra m vnvrbn PATRICK J. WOOD/N6 u M4 4 3 a ATTORAEYS.

PATENIED was] an snatr u 0F 4 IIIIIII' \NE m wt ATTORNEYS.

' CONSUMABLE ELECTRODE FURNACE rod 22 and'hence the electrode clamps 18 can be reciprocated This application is'a continuation of application Ser. No.

6,17,228filed Feb. 20, 1967, now abandoned.

l This invention relates to a consumable electrode furnace. More particularly, this invention relates to a consumable elect'i'ode furnace capable of producing more than one ingot with a single suspension system and power supply. The furnace includes means for supporting a plurality of electrodes aligned with individual crucible's'and supplying electrical power to the individual electrodes and their crucibles from a common source.

l-leretofore it has been the practice in the consumable electrode' art to provide a single suspension'system and set of electrical controls for each individual electrode to be remelted. It is well known to produce a single ingot from three electrodes with independent suspension systems and a common threephase power supply or three direct current power supplies. More than one electrode supported from one suspension system in a single crucible is well'known. Since the electrode suspension system and thecon'trols therefor are a major portion of the cost of a consumable electrode furnace, it follows that the melting of multiple electrodes would be much less expensive in terms of the cost of the melting apparatus if a single upwardly or downwardly as required. Brushes 26 make sliding contact with the conductors. 18 as they move up and down with the disk 12.

1n the furnace 10, a plurality of water cooled crucibles 32 are mounted with their topmost opening adjacent the floor 34.

suspension system and regulator can be used. The present invention concerns apparatus for simultaneously melting several electrodes in individual crucibles using a single suspension system and a single set of regulator controls with provision for additional regulators if desired.

As hereafter more fully explained, melting several electrodes in individual crucibles using one suspension system and a single source of power has heretofore been considered wholly impractical if not impossible due to current balancing problems and the like. The present invention has taken into account and resolved these problems. In particular, it has been determined that such' a furnace can be constructed and operated in a manner whereby it is self-balancing.

It is an object to provide a novel consumable electrode furnace and method of melting electrodes which is simple, reliable, economical and faster than those proposed heretofore.

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1 is an elevation view of the consumable electrode apparatus of the present invention with portions in section.

FIG. 2 is a top plan view of FIG. 1.

FIG. 3 is an elevation view, partly in section, of a portion of another embodiment.

FIG. 4 is a top plan view of the embodiment of FIG. 3.

FIG. 5 is a block diagram of the regulator control system.

Referring now to the drawing in detail, wherein like numerals indicate like elements, there is shown in FIG. 1 a consumable electrode furnace designated generally as 10.

A disk -12 is connected to a hub 14 and reinforced by a plurality of braces 16. The disk 12 is connected to a plurality of conductors 18, each coupledto a single source. The conductors 18 themselves may be hollow so that a coolant can be passed therethrough.

Eight electrode stub clamps 20 are supported by the disk 12 adjacent the periphery thereof in electrical connection with conductors 181 Such electrical connection can be by use of an electrically conductive disk 12 or by conductors supported by disk 12. Althoughv only eight such clamps have been illustrated, those skilled in the art will readily recognize that the number of clamps is limited only by the capacity of the supporting structure so that 12 or even 24 such clamps could be used. The clamps 20 are well known in the art and need not be described in detail.

The hub 14' is connected to the upper end of a telescoping support rod 22 which extends into a cylinder 24. Rod 22' is fixed to a piston not shown which is adapted to be reciprocated within the cylinder 24 by the application of The crucibles 32 are conventional and therefore'need not be described in detail. However, it should be noted that in the furnace 10, there are eight crucibles each spaced to receive one of the electrodes 36 supported by the clamps 20.

The furnace 10 is operated as follows: i

The electrodes 36 are attached to the clamps 20. This may be done by lowering the electrode downwardly through the clamps 20 until the upper endof the electrodes are adjacent the clamps. Thereafter, the clamps may be mechanically locked to the electrodes 36. Such mechanical locking will also electrically couple the electrodes 36 to the disk 12 by way of the clamps 20. Thereafter, the electrodes are lowered into their respective crucibles by applying a hydraulic fluid into the cylinder 20 by way of conduit 28. I

In the illustrated embodiment, the melting process is preferably of the electroslag type wherein the lower each of the electrodes is positioned within a layer of slag floating upon a pool of molten metal within the crucibles. For startup the layer of slag can be powdered or liquid, but liquid is preferred. Once the electrodes have been appropriately positioned, the furnace 10 can be energized to begin the melting operation. Such a multiple melting operation with a single regulator and set of instruments is particularly applicable to. the electroslag process because the system is self-balancing in terms of the amount of current being applied through each electrode. In the event that one of the electrode-crucible combinations does not start up, then the clamp 20 for that electrode is opened, thereby breaking the electrical connection. During the melting operation, this clamp will merely slidedown the electrode. The clamps 20 may be provided with an electrically operated snap lock of the solenoid type to affect opening and closing.

The instrumentation is best explained in connection with the block diagram in FIG. 5.

As shown more clearly in FIG. 5, each of the crucibles are connected to a flux path sensor 38 which detects the lengthof the resistance path from the end of the electrode and transmits a signal representative thereof through a flux path regulator 40, variable speed drive 42, differential 44, and command transducer 46 to an'error signal comparator 48. Movement of the piston connected to the rod 22 within the cylinder 24 is detected by a position transducer 50 and a signal indicative thereof is also transmitted to the error signal comparator 48.

The comparator 48 compares the error signals received and transmits a signal through a servoamplifier 52 to a servo valve 54. Servo valve 54, depending upon the signal it receives, will cause the introduction of a motive fluid through either

conduit

28 or 30 to effect a positioning of the rod 22 up or down.

Controls

56 and 58 respectively operate a solenoid valve 60 for moving the ram high speed up or high speed down. In addition, a selectively operable control 62 may be coupled through the differential 44 to effect creep movement of the ram up and down and any other type of control action.

If the impedance or resistance, depending on whether alternating or direct current is used, becomes less in one electrodecrucible combination than in the remainder, it will of course begin to conduct more current. However, the increase in cur rent causes the electrode tomelt more rapidly and hence increases the arc length or resistance gap until the impedance through this particular electrode-crucible is equal to the I remaining crucibles. Thus, the device is self-compensating.

In FIGS. 3 and 4, there is illustrated another furnace of the present invention designated generally as The furnace 10' I v is identical with the furnace 10 except as will be made clear hereinafter. Accordingly, corresponding structure will be provided with corresponding primed numerals.

In the furnace 10', the cylinder 24' and the brushes 26' are supported by a housing 70 mounted for rotation about the lon' gitudinal axis of rod22'. Rotation is effected by means of a hydraulic cylinder 72 having a piston 73 connected to a link Mon brace 16. 1

Cylinder. 72 and piston 73 are generally tangent to a circle which is concentric with the longitudinal axis of rod 22.. Where angles'of rotation greater than the throw of a practical piston are required, then a motor and gear means maybe used.

As shown more clearly in F IG. 4, the disk 12' supports at its periphery a smaller number of electrode clamps as compared with the number of crucibles. Thus, in FIG. 4, there is illustrated l2 crucibles 32 and only eight clamps 20'. The clamps 20 at the I2 o'clock, 3 oclock, 6 o'clock and 9 oclock positions are melting stations wherein the clamp is mechanically and electrically coupling the electrode to the disk 12'. While those electrodes are being melted, the clamps at the 1 oclock, 4 oclock, 7 oclock and 10 oclock positions are open so that new electrodes may be loaded and coupled thereto. The

remaining crucibles at the 2 o'clock, 5 oclock, 8 oclock and ll 'oclock positions are exposed from above so that the melted electrodes may be stripped.

When'the ingots have been stripped from the exposed crucibles and the remaining electrodes have been melted, cylinder 72 may be actuated to rotate the disk 12 through an arc of 30". This will place the newly attached electrodes above an empty crucible and facilitate removal of electrode stubs and loading of new electrodes. At all times, there will be some electrodes being melted, some electrodes being attached to the clamps, and some ingots solidifying within the crucibles or being stripped from the crucibles. Except as noted, the furnace 10' is identical with furnace l0.

The furnace described above is symmetrical in design and thus provides a symmetry for the conducting path between the power source and each electrode. Recognizing that alternating current is the most economical form of power for use for electroslag melting, it is important that the reactance of each of the electrode loops be kept reasonably equal since circuit reactance can often be more critical than resistance in determining the flow of 50 or 60 cycle current.

Consideration of the foregoing has an important bearing on the design of the apparatus. However, it should be recognized that the principal impedance in the circuit is the flux path (molten slag in electroslag reduction) and that variation of the length of this flux path by a few percent of its overall length produces only minor variations, if any, in the metallurgy of the electroslag process. For example, if the impedance of the flux path is 80 percent of the total impedance and the mechanical design of the furnace allows for a maximum of 10 percent difference in impedance in each of the secondary bus circuits,

percent, or 2 percent of the length of the flux path. Moreover,

there is no difficulty in making the resistance of each of the bus bars approximately equal. This, taken in combination with the physical symmetry of the apparatus will maintain the wattless component of the reactance small enough that only minor inequalities can occur. Thus, any significant change in impedance is the result of an electrode being resistance melted within the molten slag at a rate that is greater than the remaining electrodes. As explained above, this is self-compensated by a lowering or raising of the current flowing through that particular electrode and hence a change in the rate of melting.

The self-compensating effect of the aforesaid apparatus and method is just as effective when used with a three-phase supply as with a single-phase supply. In the case of a threephase supply, there could be six electrodes and each phase could feed one pair. This would have the added benefit of avoiding any imbalance in the' local plant or distribution system; I v

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made-to the ap pended claims, rather than to theforegoing specification as indicating the scope of the invention.

It is claimed:

1. An electroslag process for simultaneously producinga plurality of ingots in a consumable electrode furnace by simultaneously melting a plurality of electrodes into a plurality of ingot forming crucibles, comprising 'the steps of attaching a plurality of electrodes to a single support structure so that each crucible has at least one electrode projecting into it, positioning and maintaining the electrodes within the crucibles partially under slag, simultaneously conducting electrical energy from a common power supply to each of the electrodes and crucibles, said electrical energy being of sufficient quantity to simultaneously fuse each of the electrodes under slag into its crucible to form aningot therein, and controlling the fusion of said electrodes during the melting operation from only one regulator control means for controlling means for simultaneously adjusting the relative position of said electrodes and crucibles.

2. An electroslag process in accordance with claim 1 wherein the furnace has additional unused crucibles during the melting operation, and the operation of said furnace includes the further steps .of attaching additional electrodes to the support structure while said first mentioned electrodes are being melted, completing said first melting operation, displacing the electrode support structure after the first mentioned electrodes have been melted so as to position the additionally attached electrodes over empty crucibles, then recommencing the electrode melting operation, and stripping ingots formed by the first melting operation from their crucibles while the additional electrodes are being melted.

3. An electroslag furnace for simultaneously producing a plurality of ingots by simultaneously melting under slag at least one consumable electrode in each one of a plurality of ingot forming crucibles comprising, a plurality of ingot forming crucibles each for forming an ingot whenan electrode is melted into it only one electrode support means for supporting all of a plurality of electrodes during the electrode melting operation and holding each electrode in alignment with a crucible so that each electrode may be'supported within a crucible during the melting operation for simultaneously melting at least one electrode into each of a plurality of said crucibles, only one common power supply connected through conductive means to each crucible and to the support means for 7 each electrode for providing electrical energy from the power a supply to the electrodes for simultaneously fusing the electrodesunder slag into the plurality of crucibles during the melting operation, means for effecting relative movement of the support means and the crucibles toward and away from each. other so that the position of all of the electrodes that are within the crucibles may be simultaneously adjusted during the melting operation, and only one regulator control means for controlling said relative movement.

4. An electroslagfurnace for simultaneously producing a plurality of ingots by simultaneously melting under slag one consumable electrode in each one of a plurality of ingot form.

ing crucibles comprising, a plurality of ingot forming crucibles each for forming an ingot when an electrode is melted into it,

only one electrode support means for supporting all of a plurality of electrodes during the electrode melting operation,

said support including clamping means for attaching each electrode to said support, said clamping means being mounted each of a plurality of crucibles, only one power supply connected through conductive means to each said crucible and to the clamping means for the electrodes for providing electrical energy from the power supply to the electrodes for simultaneously fusing the electrodes under slag into the plurality of crucibles during the melting operation, each crucible being positioned below and in axial alignment with said clamping means for receiving an electrode held by said clamping means during the ingot forming process, means for effecting relative movement between said clamping means and said crucibles, said relative movement of said clamping means and crucibles being toward and away from each other whereby the position of all of the electrodes that are supported within crucibles may be simultaneously adjusted during the melting operation, and only one regulator control means for controlling said relative movement to position the electrodes in response to a detected electrical characteristic of the electrical energy for fusing the electrodes.

5. An electroslag process for simultaneously producing a plurality of ingots in a consumable electrode furnace by simultaneously melting a plurality of electrodes into a plurality of ingot forming crucibles, comprising the steps of attaching a plurality of electrodes to a common support structure so that each crucible has at least one electrode projecting into it, posi-- tioning and maintaining the electrodes within the crucibles partially under slag, simultaneously conducting electrical energy from a power supply to each of the electrodes and crucibles, said electrical energy being of sufficient quantity to simultaneously fuse each of the electrodes under slag into its crucible to form an ingot therein, and controlling the fusion of said electrodes during the melting operation from only one regulator control means for controlling means for simultaneously adjusting the relative position of said electrodes and crucibles.

6. An electroslag furnace for simultaneously producing a plurality of ingots by simultaneously melting, under slag, at least one consumable electrode in each one of a plurality of ingot forming crucibles comprising, a plurality of ingot forming crucibles each for forming an ingot when an electrode is melted into it, only one support means for supporting all of a plurality of electrodes during the electrode melting operation, clamp means mounted on the electrode support means for coupling each electrode to the electrode support means and holding each electrode in alignment with a crucible so that each electrode may be supported within a crucible'during the melting operation for simultaneously melting at least one electrode into each of a plurality of said crucibles, only one power supply connected through conductive means to each crucible and to the clamp means for each electrode for providing electrical energy from the power supply to the electrodes for simultaneously fusing the electrodes under slag into the plurality of crucibles during the melting operation, means for effecting relative movement of the clamp means and the crucibles toward and away from each other so that the position of all of the electrodes that are within the crucibles may be simultaneously adjusted during the melting operation, and only one regulator control-means for controlling said relative movement;

7. A consumable electrode furnace in accordance with claim 6 wherein the clamp means includes a plurality of electrode clamps, and said electrode clamps are less in number than the number of said crucibles.

8. A consumable electrode furnace in accordance with crucible,

9. An electroslag process in accordance with claim 5 including the steps of arranging the electrical path between said power supply and said electrodes and' crucibles so that it is geometrically symmetrical.

10. An electroslag furnace for simultaneously producing a plurality of ingots by simultaneously melting under slag one consumable electrode in each one of a plurality of ingot forming crucibles comprising, a plurality of ingot forming crucibles each for forming an ingot when an electrode is melted into it, a single electrode support means for supporting all of a plurality of electrodes during the electrode melting operation, said support including a plate mounted thereon, clamping means for attaching each electrode to said plate, said clamping means being mounted in spaced apart positions on said plate, said clamping means being adapted for supporting each electrode in alignment with a separate crucible so that each electrode may be supported within a particular crucible during the melting operation for simultaneously melting at least one electrode into each of a plurality of crucibles, a common power supply connected through conductive means to each crucible and to the clamping means for the electrodes for providing electrical energy from the power supply to the electrodes for simultaneously fusing under slag into the plurality of crucibles during the melting operation, each crucible being positioned below and in actual alignment with said clamping means for receiving an electrode held by said clamping means during the ingot forming process, means for effecting relative movement between said clamping means and said crucibles, said relative movement of said clamping means and crucibles being toward and away from each other, said means for effecting relative movement including an hydraulic ram, whereby the position of all of the electrodes that are supported within crucibles may be simultaneously adjusted during the melting operation, and a single regulator control means for controlling said relative movement to position the electrodes in response to an electrical characteristic of the electrical energy for fusing the electrodes.

Claims

1. An electroslag process for simultaneously producing a plurality of ingots in a consumable electrode furnace by simultaneously melting a plurality of electrodes into a plurality of ingot forming crucibles, comprising the steps of attaching a plurality of electrodes to a single support structure so that each crucible has at least one electrode projecting into it, positioning and maintaining the electrodes within the crucibles partially under slag, simultaneously conducting electrical energy from a common power supply to each of the electrodes and crucibles, said electrical energy being of sufficient quantity to simultaneously fuse each of the electrodes under slag into its crucible to form an ingot therein, and controlling the fusion of said electrodes during the melting operation from only one regulator control means for controlling means for simultaneously adjusting the relative position of said electrodes and crucibles.

2. An electroslag process in accordance with claim 1 wherein the furnace has additional unused crucibles during the melting operation, and the operation of said furnace includes the further steps of attaching additional electrodes to the support structure while said first mentioned electrodes are being melted, completing said first melting operation, displacing the electrode support structure after the first mentioned electrodes have been melted so as to position the additionally attached electrodes over empty crucibles, then recommencing the electrode melting operation, and stripping ingots formed by the first melting operation from their crucibles while the additional electrodes are being melted.

3. An electroslag furnace for simultaneously producing a plurality of ingots by simultaneously melting under slag at least one consumable electrode in each one of a plurality of ingot forming crucibles comprising, a plurality of ingot forming crucibles each for forming an ingot when an electrode is melted into it, only one electrode support means for supporting all of a plurality of electrodes during the electrode melting operation and holding each electrode in alignment with a crucible so that each electrode may be supported within a crucible during the melting operation for simultaneously melting at least one electrode into each of a plurality of said crucibles, only one common power supply connected through conductive means to each crucible and to the support means for each electrode for providing electrical energy from the power supply to the electrodes for simultaneously fusing the electrodes under slag into the plurality of crucibles during the melting operation, means for effecting relative movement of the support means and the crucibles toward and away from each other so that the position of all of the electrodes that are within the crucibles may be simultaneously adjusted during the melting operation, and only one regulator control means for controlling said relative movement.

4. An electroslag furnace for simultaneously producing a plurality of ingots by simultaneously melting under slag one consumable electrode in each one of a plurality of ingot forming crucibles comprising, a plurality of ingot forming crucibles each for forming an ingot when an electrode is melted into it, only one electrode support means for supporting all of a plurality of electrodes during the electrode melting operation, said support including clamping means for attaching each electrode to said support, said clamping means being mounted at spaced apart positions on said support, said clamping means including means for supporting each electrode in alignment with a separate crucible so that each electrode may be supported within a particular crucible during the melting operation for simultaneously melting at least one electrode into each of a plurality of crucibles, only one power supply connected through conductive means to each said crucible and to the clamping means for the electrodes for providing electrical energy from the power supply to the electrodes for simultaneously fusing the electrodes under slag into the plurality of crucibles during the melting operation, each crucible being positioned below and in axial alignment with said clamping means for receiving an electrode held by said clamping means during the ingot forming process, means for effecting relative movement between said clamping means and said crucibles, said relative movement of said clamping means and crucibles being toward and away from each other whereby the position of all of the electrodes that are supported within crucibles may be simultaneously adjusted during the melting operation, and only one regulator control means for controlling said relative movement to position the electrodes in response to a detected electrical characteristic of the electrical energy for fusing the electrodes.

5. An electroslag process for simultaneously producing a plurality of ingots in a consumable electrode furnace by simultaneously melting a plurality of electrodes into a plurality of ingot forming crucibles, comprising the steps of attaching a plurality of electrodes to a common support structure so that each crucible has at least one electrode projecting into it, positioning and maintaining the electrodes within the crucibles partially under slag, simultaneously conducting electrical energy from a power supply to each of the electrodes and crucibles, said electrical energy being of sufficient quantity to simultaneously fuse each of the electrodes under slag into its crucible to form an ingot therein, and controlling the fusion of said electrodes during the melting operation from only one regulator control means for controlling means for simultaneously adjusting the relative position of said electrodes and crucibles.

6. An electroslag furnace for simultaneously producing a plurality of ingots by simultaneously melting, under slag, at least one consumable electrode in each one of a plurality of ingot forming crucibles comprising, a plurality of ingot forming crucibles each for forming an ingot when an electrode is melted into it, only one support means for supporting all of a plurality of electrodes during the electrode melting operation, clamp means mounted on the electrode support means for coupling each electrode to the electrode support means and holding each electrode in alignment with a crucible so that each electrode may be supported within a crucible during the melting operation for simultaneously melting at least one electrode into each of a plurality of said crucibles, only one power supply connected through conductive means to each crucible and to the clamp means for each electrode for providing electrical energy from the power supply to the electrodes for simultaneously fusing the electrodes under slag into the plurality of crucibles during the melting operation, means for effecting relative movement of the clamp means and the crucibles toward and away from each other so that the position of all of the electrodes that are within the crucibles may be simultaneously adjusted during the melting operation, and only one regulator control means for controlling said relative movement.

8. A consumable electrode furnace in accordance with claim 6 wherein the clamp means includes a plurality of electrode clamps for coupling the electrodes to the electrode support means, the number of crucibles being greater than the number of clamps, and means for laterally displacing said electrode support and crucibles relative to each other so that each clamp may be moved from alignment with one crucible to alignment with another crucible, whereby one crucible may be stripped while an electrode is being melted in an adjacent crucible.

9. An electroslag process in accordance with claim 5 including the steps of arranging the electrical path between said power supply and said electrodes and crucibles so that it is geometrically symmetrical.