Sealed tilt-dump electric induction furnace for reactive alloys and metals

Abstract

A sealed tilting electric induction furnace and furnace system are provided for supplying active molten material from the furnace to an active molten material processing device without exposing the active molten material to the surrounding environment. A rotating assembly of a rotary joint is connected to an enclosed furnace pouring spout of the furnace and rotates simultaneously with the tilting pouring furnace about a common horizontally oriented rotational axis to supply the active molten material to the active molten material processing device connected to the fixed assembly of the rotary joint.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 620,550, filed January 23, 2018, which is hereby incorporated by reference herein in its entirety. Technical Field

[0003] The present invention relates to electric induction furnaces and furnace systems for heating and melting reactive alloys and metals and supplying molten reactive alloys and metals for use in industrial processes such as direct chill casting or die casting lines, wherein the injected reactive molten material is isolated from elements in the surrounding environment, such as oxygen in the air. Background Art

[0004] In the prior art, the inclined port in an inclined electric induction furnace is usually arranged with its inclination angle oriented perpendicularly (90 degrees) to the tilt axis of the furnace, for example, as disclosed in US Pat. No. 9,332,594 B2.

[0005] If the molten material requires a protective cover gas environment of air or other ambient environment, the tilting induction furnace can be placed in a protective cover gas sealed container in which the pouring takes place. Other known equipment and methods of protecting the tilting area from air are complex and expensive.

[0006] It is an object of the present invention to provide a tilt-dump electric induction furnace and furnace system and method of using the same which can supply molten reactive metal or metal alloy from a tilted electric induction furnace wherein the material from the furnace is protected from interaction with the air or other surrounding environment in a relatively cost-effective apparatus and method compared to those known in the art.

[0007] Other objects of the invention are disclosed in the present description as well as in the drawings and claims. Summary of the Invention

[0008] In one aspect, the present invention is a tilt-dump electric induction furnace and furnace system for heating, melting, or heating and melting reactive metals or metal alloys where it is desired to isolate the metal or alloy from air or other surrounding environment while transferring the molten metal or alloy from the furnace to a molten metal processing system.

[0009] In another aspect, the present invention is a method of delivering molten reactive metal or reactive molten metal alloy from a tilt-dump electric induction furnace and furnace system, wherein the reactive metal or reactive molten metal alloy is heated, melted, or heated and the metal or alloy is isolated from air or other surroundings during casting and then delivered to a molten metal processing system.

[0010] These and other aspects of the invention are set out in the specification and drawings, and in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings, briefly summarized below, are provided for illustrative understanding of the present invention and are not limiting of the invention further described in the specification and appended claims.

[0012] Figure 1 is a top view of an example of an upper tilt-dump furnace vessel of one embodiment of the tilt-dump furnace system of the present invention, and a sealed connecting tilt interface from the furnace system to an active molten material processing apparatus.

[0013] Figure 2 is through Figure 1 Cross-sectional elevation view of the upper inclined dump furnace vessel shown along the center line AA.

[0014] 3( a ), 3 ( b ), 3 ( c ) and 3 ( d ) illustrate the tilted positions of an exemplary upper tilt pouring furnace vessel about a rotatable tilt pouring axis of the furnace vessel when the sealed electric induction furnace system of the present invention is pouring active molten material from the furnace vessel or removing slag from the furnace vessel.

[0015] Figure 4 Shows the connection to Figure 1 and Figure 2 The upper tilted dumping furnace vessel is shown to form an example of a lower electric induction furnace vessel of the sealed tilted electric induction furnace of the present invention.

[0016] Figure 5 FIG. 1 is an example of a simplified furnace tilt control system diagram for the sealed tilt electric induction furnace and furnace system of the present invention. DETAILED DESCRIPTION

[0017] exist Figure 1 and Figure 2 An example of an upper tilting pouring furnace vessel 10 used in the present invention is shown in FIG. The upper tilting pouring furnace vessel is also referred to herein as the "upper shell." In the embodiment of the present invention shown, the upper tilting pouring furnace vessel has an outer structural shell 10a and an inner refractory material 10b, which are selected from suitable materials known in the art to form an insulated active material holding container. The volume within the refractory material defines the active material batch pouring capacity line ( Figure 2 The typical upper shell internal furnace volume 10d is from the exemplary MLL maximum load line in FIG. 1 to the open throat molten metal region 13 at the bottom of the upper inclined dump furnace vessel 10, with an overlying gas freeboard volume ( Figure 2 Middle FB freeboard area), in the embodiment of the present invention shown, area 13 connects the upper inclined dump furnace vessel 10 to the lower furnace vessel 30.

[0018] In the embodiment of the invention shown in the drawings, the interior furnace volume 10d of the upper shell is generally cylindrical in shape from a top interior region to a bottom dish (or bowl) shaped region with a central bottom opening into a throat molten material region 13 .

[0019] Figure 4 An example of a lower electric induction furnace vessel 30 is shown, which is a coreless electric induction melting and heating furnace, and is combined with the upper tilt-tilt pouring furnace vessel 10 to form an embodiment of the sealed tilt-tilt pouring electric induction furnace 50 of the present invention. The coreless electric induction melting and heating furnace can be as disclosed in U.S. Patent Application Publication No. 2016 / 0242239 A1, or other known in the art (depending on the specific application).

[0020] As is known in the prior art, Figure 4 In the illustrated electric induction furnace vessel 30, a suitable AC power source (not shown in the drawings) is provided to supply AC power to the inductor 30a, wherein active material 30d is shown within the electric induction furnace vessel. As further disclosed in U.S. Patent Application Publication No. 2016 / 0242239 A1, in some embodiments of the present invention, a cooling channel 30b may optionally be provided between one or more inductors 30a and the refractory material 30c.

[0021] When the upper tilting pouring furnace vessel of the present invention as described herein is used to pour active molten material, such as Figure 4 As shown, the lower electric induction furnace vessel is connected to the upper tilt-dump furnace vessel and tilts together with the upper tilt-dump furnace vessel. Although the furnace system is also used in a furnace batch dump process as described herein, the furnace and furnace system of the present invention are used with multiple single-dump active molten material handling devices for molten material handling systems (such as mold filling lines).

[0022] exist Figure 1 and Figure 2In the embodiment of the invention shown, the upper tilt pour furnace vessel 10 and the rotating assembly 20a of the rotary joint 20 are both configured to rotate simultaneously about a common trunnion (or axis) "TT" when tilting and pouring active molten material from a closed furnace mouth 12a - in this embodiment of the invention, the furnace mouth 12a generally protrudes from the interior space of the upper tilt pour furnace vessel at or above the active material batch tilting capacity line. In this embodiment of the invention shown in the figures, the upper tilt pour furnace vessel 10 (with the attached lower furnace vessel 30) and the rotating assembly 20a of the rotary joint are rotated simultaneously by a suitable drive (e.g., a powered linear drive that produces rotational motion, such as an electric or hydraulic drive known in the art and shown, for example, in U.S. Patent No. 9,332,594 B2). The rotary joint 20 allows the tilting dump furnace to rotate via the stationary component 20b of the rotary joint (connected to the handling device 32a) and the rotating component 20a connected to the closed furnace dump spout 12a to dump the reactive molten material without exposing it to the surrounding environment between the stationary reactive molten material handling devices 32a and 32b, as shown. Figure 1 As shown, the active molten material is allowed to flow from the interior 10d of the upper tilt pour furnace vessel 10 to the processing devices 32a and 32b, which feed the active molten material to industrial processing equipment (not shown in the figure), such as direct chill casting or mold filling processing equipment. The rotary joint 20 is selected according to the specific application of a person skilled in the art. The active molten metal material processing equipment 32a and 32b represent one or more processing equipment, such as closed metal launders known in the art, to transfer the active molten material to a specific industrial process, such as direct chill casting or mold filling line.

[0023] The closed furnace pour spout 12a extends from the outer periphery of the upper inclined pour furnace vessel 10 to the upper inclined pour furnace vessel 10 via a sealed environmental connection and is located at or above the maximum capacity horizontal active material loading line (MLL) when the upper furnace vessel is horizontally (non-dumped) oriented as shown in Figure 3(a) at 0 degrees (horizontal). In the embodiment of the present invention shown in the figure, the closed furnace pour spout 12a feeds molten active material through a nozzle 12b that passes through the wall of the upper inclined pour furnace vessel (in the embodiment shown, the outer structural shell 10a and the inner refractory material 10b) to the inner volume 10d of the upper inclined pour furnace vessel and terminates at an inner nozzle opening 12c that is located near the lower periphery of the main inner volume 10d and above the transition inner molten material volume 13 between the upper inclined pour furnace vessel and the lower electric induction furnace vessel. As shown Figure 2As shown, in the embodiment of the present invention shown in the figure, the internal nozzle opening 12c is located at a distance d1 above the transition internal volume. The distance d1 is selected in a specific application to maximize the volume of batch pouring molten material available in the main internal volume 10d. Typically, but not limited to, the nozzle 12b can be an open cylindrical cross-sectional shape, while the internal nozzle opening 12c where the nozzle ends can be an elliptical cross-sectional shape of an opening on the inner wall of the furnace. Generally speaking, the furnace mouth assembly includes an enclosed furnace mouth 12a, a nozzle 12b and an internal nozzle opening 12c, and when the upper tilting pouring furnace vessel (with a connected lower electric induction furnace vessel) is rotated and tilted about the furnace tilt trunnion or axis "TT", the furnace mouth assembly draws molten active material from the lower main internal volume of the furnace to the sealed furnace mouth by gravity feeding.

[0024] like Figure 1 As shown, in the illustrated embodiment of the present invention, the closed furnace port 12a is located approximately 235 degrees from the horizontally oriented furnace tilt rotation axis "TT" (0-180 degrees in the axial orientation) in a top plan view of the upper furnace vessel. In other embodiments of the present invention, the angular position of the closed furnace port may vary, as long as the angle is not perpendicular (90 degrees) to the furnace tilt rotation axis.

[0025] The active molten material from the tilted dumping furnace is isolated from the external environment (e.g., air with an oxygen content) and passes sequentially from the internal nozzle opening 12c through the furnace nozzle 12b, the closed furnace mouth 12a, and the sealed rotating and stationary assembly of the rotary joint 20 (connected to the active molten material processing equipment 32a by the flange 20' in the example shown) to transport the active molten material to the processing equipment in the specific application.

[0026] In a typical batch pouring method of the present invention shown in the drawings, when the upper furnace vessel 10 and the attached lower furnace vessel 30 contain a sufficient amount of a designated active molten material (for batch pouring the active molten material from the upper furnace vessel), the upper furnace vessel 10 (to which the lower furnace vessel 30 is attached) and the rotating assembly 20a of the rotary joint 20 are simultaneously rotated about axis "TT" while the fixed assembly 20b of the rotary joint 20 remains fixed. For the orientation of the embodiment of the present invention shown in the drawings, as shown in the detail of FIG. 3 , the rotation is counterclockwise T. CCR Rotation, where counterclockwise rotation is X degrees relative to the horizontal (zero degrees). The maximum tilt pouring angle of the embodiment of the furnace system shown in the figure is determined by the highest vertical point at which the nozzle opening 12c enters the furnace interior space; the material in the upper furnace container is maintained at least at the highest point of the opening 12c ( Figure 2 The height of point P1) ( Figure 2The material in the furnace follows the line MHL) to prevent oxygen or other undesirable elements from the surrounding environment from entering the furnace and combining with the active material. To ensure this condition, the lowest melt level tolerable in the furnace is maintained as the minimum melt level (MHLM), e.g. Figure 2 and two feet above the highest vertical point in Figure 3(c).

[0027] Laser (or other suitable) molten active material level sensor 31 may be provided in active molten material processing equipment 32a and / or 32b, such as a closed molten metal launder known in the art, connected to a Figure 1 In one embodiment of the present invention, the liquid level sensor 31 in the processing device 32b can be arranged to sense a fixed, specified flow height of the molten active material (maintained during batch pouring (also known as "casting")), output the sensed height to the rotary drive, which rotates the furnace about the axis "TT" as needed to change or maintain the rotational position to meet the flow direction connection Figure 1 In other embodiments of the present invention, one or more laser sensors may be used in the closed furnace port 12a and / or in the selected active molten material processing equipment.

[0028] For the embodiment of the furnace and furnace system shown in the figures, as shown in FIG3(d), when the slag door 16 is opened, the upper furnace vessel (attached to the lower furnace vessel) is rotated T clockwise from the horizontal about the axis "TT" CR Y degrees to remove the top slag from the surface of the molten active material in the upper furnace vessel through the slag chute 16a. In the embodiment of the present invention shown in the drawings, the slag door 16 is interlocked with an atmospheric purge system known in the art to prevent the introduction of oxygen or other undesirable elements into the furnace interior when the slag door is open.

[0029] In certain applications, the interior space of the upper furnace vessel is preferably configured so that when a particular batch of molten active material is poured from the closed furnace port 12 a, sufficient molten material will remain in the interior space of the lower furnace vessel to electromagnetically couple with the magnetic field generated by the alternating current in the inductor 30 a of the lower furnace vessel to avoid low load (molten material) impedance that could cause the power source providing the alternating current to the inductor to draw excessive current.

[0030] Cold-start operation of the sealed tilt-dump electric induction furnace of the present invention requires establishing a minimum amount of molten active material within the furnace. One method for establishing this minimum amount is to add the active material to the furnace through an optional charging port 18 located at the top 22 of the upper furnace vessel. In other embodiments of the present invention, the furnace top 22 may alternatively be a fixed roof structure or a removable cover. The charging port is positioned to prevent loss of the blanket gas atmosphere within the furnace interior volume when charging the charge into the furnace.

[0031] In the embodiment of the present invention shown in the accompanying drawings, the charging loading opening 18 includes a charging environmental locking chamber that cooperates with a charging container (not shown in the drawings) to establish an environmentally sealed chamber with the charging container before the charging locking chamber allows the furnace top opening doors 18a and 18b to be opened, so that the environmentally sealed paired charging container can release the charge from the top 18c of the charging port through the open furnace roof 22 to the interior of the furnace.

[0032] In some embodiments of the present invention, a sealed charging hopper is used to prevent unnecessary addition of air to the system when adding charge to the upper furnace vessel. A sealed feeder can be provided to add the charge through the charge loading opening 18. When the charge is placed in the top opening of the upper furnace, the feeder can be purged with a blanket gas, such as argon, before adding the charge to the furnace system.

[0033] For a cold start, the lower furnace may be inductively loaded initially with a molten charge, while the charge continues to be loaded into the interior space, melting into the initially molten active material until a minimum level is reached.

[0034] Initially and after each batch casting (pouring), a minimum level is maintained above the internal nozzle 12c to prevent harmful air (oxygen components) from entering the furnace and causing violent reactions with the reactive alloy or metal in the furnace vessel as further described herein.

[0035] Figure 5An example of a simplified constant volume batch furnace delivery control system 60 is schematically illustrated. A programmable logic controller (PLC) commands the rotary drive 39 to rotate the furnace 50 (the upper furnace 10 and lower furnace 30 containers) and tilt the rotary assembly of the rotary joint 20 about the tilt axis TT to a nominal furnace tilt angle X degrees. A furnace level sensor 31 reports the furnace flow level in the molten active material delivery device 32a and / or 32b to the PLC. In a quantitative batch furnace delivery mode, the PLC commands the rotary drive 39 to deviate from the nominal furnace tilt angle X degrees to maintain a constant volumetric (liquid level) flow rate, as reported by the furnace level sensor 31. A furnace load sensor (LC) reports the weight of the furnace to the PLC to determine the amount of material loaded into the furnace. An inclinometer is used to command the rotary drive 39 to reverse the tilt rotation to return the furnace 50 to a horizontal orientation to meet the minimum furnace level (by weight) in the furnace 50. During the tilt dump, if the inductor 30a operates abnormally, the power supply (PS) reports the inductor failure to the PLC, and the PLC instructs the rotation driver 39 to return the furnace 50 to the Figure 2 Horizontal position in .

[0036] Covering the gas handling and control system by tilting the freeboard area of ​​the electric induction furnace towards the seal of the present invention ( Figure 2 A blanket gas, such as argon, is supplied to the charge feeder via a purge line (FB) and a sealed charge feeder. In one embodiment of the present invention, the blanket gas handling and control system includes purge lines supplied by two independently managed blanket gas handling and control subsystems. The system includes two oxygen monitoring sensors, one pump for each melting station. The oxygen monitors measure the system's blanket gas supply and exhaust to ensure that oxygen levels throughout the charge feeder and furnace remain below 0.1%. Starting with an atmospheric oxygen concentration of approximately 21%, the atmosphere control system subsystem reduces the oxygen concentration in the furnace and charge feeder atmosphere to below 0.1% oxygen within three minutes.

[0037] In some embodiments of the present invention, a cover gas supply and handling system may optionally be provided for the enclosed outer furnace port 12a, the rotary joint 20, and / or the molten reactive material delivery apparatus, as desired for a particular application.

[0038] The terms "active material" and "active molten material" are used to define a reactive metal or reactive metal alloy, or a reactive molten metal or metal alloy, respectively. Generally, the term "reactive" refers to a metal or metal alloy that reacts in an undesirable manner if exposed to the components of the surrounding environment in which the furnace system is installed.

[0039] The present invention has been described in terms of preferred examples and embodiments. Except as expressly provided herein, equivalents, substitutes, and modifications are possible and within the scope of the present invention. Those skilled in the art who have benefited from the teachings of this specification may modify the same without departing from the scope of the present invention.

Claims

1. A method for supplying batches of reactive molten material from an electric induction furnace system to a sealed reactive molten material processing apparatus, the method comprising: charging active materials into the upper tilt-dump furnace vessel through a charging environment lock chamber provided on top of the upper tilt-dump furnace vessel, the upper tilt-dump furnace vessel being connected to the lower electric induction heating furnace vessel; Induction heating and melting the active material in the lower electric induction heating furnace container; maintaining a blanket gas within a freeboard volume above the active molten material in the upper inclined dump furnace vessel; tilting the upper tilted pouring furnace vessel about a horizontally oriented rotational tilting axis to a variable pouring angle position to pour the batched poured reactive molten material from a closed furnace pouring spout connected to an interior volume of the upper tilted pouring furnace vessel, wherein the closed furnace pouring spout is positioned obliquely and not perpendicular to the horizontally oriented rotational tilting axis; The rotary joint assembly of the sealed rotary joint is rotated about the horizontally oriented rotary tilt axis, and the upper tilt pouring furnace container is tilted about the horizontally oriented rotary tilt axis to the variable pouring angle position to transfer the active molten material from the closed furnace pouring port to the sealed active molten material processing equipment through the rotary joint assembly and the fixed joint assembly of the sealed rotary joint.

2. The method according to claim 1 further includes feeding the active molten material from the inner volume of the upper inclined pouring furnace container to the closed furnace pouring spout via an inner nozzle opening provided near the lower periphery of the inner volume of the upper inclined pouring furnace container through a nozzle penetrating the wall of the inner volume of the upper inclined pouring furnace container.

3. The method of claim 2, further comprising maintaining a minimum level of reactive molten material line above the inner nozzle opening during supply of the batch-poured reactive molten material from the electric induction furnace system.

4. The method of claim 3 further comprising angling the enclosed furnace pour spout at a horizontal angle of 235 degrees to the horizontally oriented rotational tilt axis, the horizontally oriented rotational tilt axis being axially oriented at 0-180 degrees.

5. The method of claim 4 further comprising sensing the height of the active molten material flow in the sealed active molten material processing apparatus when the upper tilted dump furnace container is in the variable dumping position, and adjusting the variable dumping position in response to changes in the active molten material flow height to maintain a constant active molten material flow height in the sealed active molten material processing apparatus.

6. The method of claim 4 further comprising sensing a flow rate of active molten material in the sealed active molten material processing apparatus when the upper tilted dump furnace container is in the variable dumping angle position, and adjusting the variable dumping angle position in response to changes in the flow rate of the active molten material to maintain a constant flow rate of active molten material in the sealed active molten material processing apparatus.

7. The method of claim 2 further comprising removing slag from the upper tilted dump furnace vessel by tilting the upper tilted dump furnace vessel about the horizontally oriented rotational tilt axis in a direction opposite to the tilting of the variable dump angle position.

8. The method of claim 2, further comprising maintaining a cover gas within the freeboard volume via the charging environment lock chamber when a charging vessel is connected to the charging environment lock chamber.

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