metal casting method

专利摘要:
APPARATUS, METAL PRODUCT CASTING, METHOD, SYSTEM, AND, ALUMINUM PRODUCT. Systems and methods are disclosed for using magnetic fields (eg alternating magnetic fields) to control metal flow conditions during casting (eg casting an ingot, billet or plate). Magnetic fields can be introduced using rotating permanent magnets or electromagnets. Magnetic fields can be used to induce molten metal movement in a desired direction, such as a rotation pattern around the surface of the molten vessel. Magnetic fields can be used to induce metal flow conditions in the molten vessel to increase homogeneity in the molten vessel and the resulting ingot.
公开号:BR112016026739B1
申请号:R112016026739-7
申请日:2015-05-21
公开日:2021-05-04
发明作者:Samuel R. Wagstaff；Wayne J. Fenton；Robert B. Wagstaff；Milan Felberbaum；Todd F. Bischoff；Tina J. Kosmicki
申请人:Novelis Inc；
IPC主号:

专利说明:

Field of Technique
[0001] The present disclosure relates to metal casting in general and more specifically to improve grain formation during aluminum casting. Fundamentals
[0002] In the metal casting method, the molten metal is passed into a mold cavity. For some types of castings, mold cavities with a false bottom, or moving, are used. As molten metal enters the mold cavity, generally from the top, the false bottom descends at a rate related to the flow rate of the molten metal. Molten metal that has solidified near the sides can be used to retain the liquid and partially liquid metal in the molten reservoir. Metal can be 99.9% solid (eg totally solid), 100% liquid, and anywhere in between. The molten sump can take a V-shape, U-shape, or W-shape due to the increase in thickness of the solid regions as the molten metal cools. The interface between liquid and solid metal is sometimes referred to as the solidification interface.
[0003] As the molten metal in the molten reservoir becomes between approximately 0% solid to approximately 5% solid, nucleation may occur and small metal crystals may form. These small crystals (eg, nanometer size) begin to form as nuclei, which continue to grow in preferential directions to form dendrites as the molten metal cools. As the molten metal cools to a dendrite coherence point (eg 632 °C in 5182 aluminum used for beverage can ends), the dendrites begin to bond. Depending on the temperature and percentage of solids of the molten metal, crystals may include or trap different particles (eg intermetallic compounds or hydrogen bubbles), such as FeAl6, Mg2Si, FeAl3, Al8Mg5 and raw H2 particles, in certain alloys of aluminum.
[0004] In addition, when crystals near the edge of the melt reservoir contract during cooling, liquid compositions still-to-solidify or particles may be rejected or squeezed out of the crystals (for example, among the dendrites of the crystals) and can build up in the melt reservoir, resulting in an imbalance of the less soluble alloying particles or elements within the ingot. These particles can move independently of the solidifying interface and have a variety of densities and fluctuating responses, resulting in the preferred configuration within the solidifying ingot. Furthermore, it cannot be the stagnation regions within the reservoir.
[0005] The inhomogeneous distribution of alloying elements in the grain length scale is known as microsegregation. In contrast, macrosegregation is the lack of chemical homogeneity on a length scale greater than one grain (or quantity of grains), such as up to the length scale of a few meters.
[0006] Macrosegregation can result in inferior material properties, which can be particularly desirable for certain uses, such as aerospace structures. Unlike microsegregation, macrosegregation cannot be fixed through typical homogenization practices (ie, prior to hot rolling). While some macrosegregating intermetallics can be broken down during lamination (eg FeAl6, FeAlSi), some intermetallic compounds take forms that are resistant to being broken down during lamination (eg FeAl3).
[0007] While the addition of new hot liquid metal into the metal reservoir creates some mixing, additional mixing may be desired. Some current mixing approaches in the public domain do not work well as they increase oxide generation.
[0008] In addition, successful aluminum blending includes challenges that are not present in other metals. Contact mixing of aluminum can result in the formation of structure-weakening oxides and inclusions that result in an undesirable molten product. Non-contact mixing of aluminum can be difficult due to the thermal, magnetic and electrical conductivity characteristics of aluminum.
[0009] In addition to oxide formation through some mixing approaches, metal oxides can form and collect as the molten metal cascades in the mold cavity. Metal oxides, hydrogen and/or other inclusions can collect as a foam or slag of oxide on top of the molten metal within the mold cavity. For example, during aluminum smelting, some examples of metal oxides include aluminum oxide, aluminum manganese oxide and aluminum magnesium oxide.
[00010] In direct cold casting, water or other coolant is used to cool the molten metal as it solidifies into an ingot as the false bottom of the mold cavity descends. Metal oxides do not diffuse heat as well as pure metal. Metal oxides that reach the side surfaces of the forming ingot (eg, through "rollover") where metal oxide from the upper surface of the molten metal migrates through the meniscus between the upper surface and a side surface ) can come in contact with the coolant and create a heat transfer barrier on that surface. In turn, the metal oxide areas contract at a different rate than the rest of the metal, which can cause stress points and therefore fractures or failures in the resulting ingot or other molten metal. Even minor defects in a cast metal part can result in much larger defects when the cast metal is rolled if not properly scalped to remove any artifacts from an earlier oxide patch.
[00011] Control of metal oxide displacement can be partially achieved through the use of skimmers. Skimmers, however, do not fully control the displacement of metal oxide and can add moisture to the casting method. Also, skimmers are not normally used when casting certain alloys, such as aluminum-magnesium alloys. Skimmers can form unwanted inclusions in molten metal. Manual oxide removal by an operator is extremely dangerous and time-consuming and risks introducing other oxides into the metal. Thus, it may be desirable to control metal oxide migration during the casting method. Brief Description of Figures
[00012] The descriptive report makes reference to the following attached figures, in which the use of similar reference numerals in different figures is intended to illustrate similar or analogous components.
[00013] FIG. 1 is a partial cross-sectional view of a metal casting system without flow inducers, in accordance with certain aspects of the present disclosure.
[00014] FIG. 2 is a top view of a metal casting system that uses flow inducers in a lateral orientation, in accordance with certain aspects of the present disclosure.
[00015] FIG. 3 is a cross-sectional diagram of the metal casting system of FIG. 2 taken through lines A-A in accordance with certain aspects of the present disclosure.
[00016] FIG. 4 is a top view of a metal casting system using flow inducers in a radial orientation for certain aspects of the present disclosure.
[00017] FIG. 5 is a top view of a metal casting system using flow inducers in a longitudinal orientation in accordance with certain aspects of the present disclosure.
[00018] FIG. 6 is an enlarged elevation view of the flux inducer of FIGs. 2 and 3 in accordance with certain aspects of the present disclosure.
[00019] FIG. 7 is an end view of a metal casting system that utilizes flow inducers in a radial orientation within a circular mold cavity, in accordance with certain aspects of the present disclosure.
[00020] FIG. 8 is a schematic diagram of a flux inductor containing permanent magnets in accordance with certain aspects of the present disclosure.
[00021] FIG. 9 is a top view of a metal casting system utilizing corner flow inducers in the corners of the mold cavity in accordance with certain aspects of the present disclosure.
[00022] FIG. 10 is an axonometric view depicting a corner flux inducer of FIG. 9 in accordance with certain aspects of the present disclosure.
[00023] FIG. 11 is an enlarged cross-sectional view of a flow inducer used with a flow director in accordance with certain aspects of the present disclosure.
[00024] FIG. 12 is a cross-sectional diagram of a metal casting system using a multi-part flow inducer that employs Fleming's Law for molten metal flow in accordance with certain aspects of the present disclosure.
[00025] FIG. 13 is a top view of a mold during a steady state stage of casting in accordance with certain aspects of the present disclosure.
[00026] FIG. 14 is a cross-sectional view of the mold of FIG. 13 taken along line B-B, during the steady-state phase, in accordance with certain aspects of the present disclosure.
[00027] FIG. 15 is a cross-sectional view of the mold of FIG. 13 taken along line C-C during the final stage of casting, in accordance with certain aspects of the present disclosure.
[00028] FIG. 16 is a close-up view of a magnetic source above molten metal in accordance with certain aspects of the present disclosure.
[00029] FIG. 17 is a top view of the mold of FIG. 13 during an initial casting phase in accordance with certain aspects of the present disclosure.
[00030] FIG. 18 is a top view of an alternative mold in accordance with certain aspects of the present disclosure.
[00031] FIG. 19 is a schematic diagram of a magnetic source adjacent to a molten metal meniscus, in accordance with certain aspects of the present disclosure.
[00032] FIG. 20 is a top view of a chute for conveying molten metal in accordance with certain aspects of the present disclosure.
[00033] FIG. 21 is a flowchart describing a casting method in accordance with certain aspects of the present disclosure. Detailed Description
[00034] Certain aspects and features of the present invention relate to the use of magnetic fields (for example, varying magnetic fields) to control the metal flow conditions during aluminum casting (for example, casting an ingot, billet or brick ). Magnetic fields can be introduced using rotating permanent magnets or electromagnets. Magnetic fields can be used to induce movement of molten metal in a desired direction, such as a rotation pattern around the surface of the molten vessel. Magnetic fields can be used to induce metal flow conditions in the molten vessel to increase homogeneity in the molten vessel and the resulting ingot. Increased flow can increase the maturation of crystals in the melt reservoir. Ripening of solidifying crystals can include rounding the shape of the crystal such that it can be packed more closely.
[00035] The techniques described here can be useful for the production of molten metal products. In particular, the techniques described herein can be especially useful for producing cast aluminum products.
[00036] During molten metal processing, metal flow can be achieved by non-contact metal flow inducers. Non-contact metal flux inductors can be magnetic based, including magnetic sources such as permanent magnets, electromagnets or any combination thereof. Permanent magnets may be desirable in some circumstances to reduce the capital costs that would be required if electromagnets were to be used. For example, permanent magnets may require less cooling and may use less energy to induce the same amount of flux. Examples of suitable permanent magnets include AlNiCr, NdFeB and SaCo magnets, although other magnets that have suitably high coercivity and remanence can be used. If permanent magnets are used, the permanent magnets can be positioned to rotate around an axis to generate a variable magnetic field. Any suitable arrangement of permanent magnets can be used, such as, but not limited to, simple bipolar magnets, balanced dipole magnets, multi-magnet arrays (eg 4 poles), Halbach matrices and other magnets capable of generating field variations magnetic when rotated.
[00037] Metal flow inducers can control, radially or longitudinally, the velocity of molten metal within a metal reservoir, such as a metal reservoir of an ingot being cast. Metal flow inducers can control the velocity of molten metal against the solidification interface, which can alter the solidification by size, shape and/or composition of the precipitated crystal. For example, using metal flow inducers to increase metal flow through a solidification interface can distribute the rejected solute alloy elements or intermetallic compounds that have been squeezed into that location and can move around the solidification crystals to help the ripening of the crystals.
[00038] Metal flux can be induced using magnetic fields due to Lorenz forces created in conductive metals as defined by Lenz's law. The magnitude and direction of forces induced in the molten metal can be controlled by adjusting the magnetic fields (eg force, position and rotation). When metal flux inductors include permanent rotating magnets, control of the magnitude and direction of forces induced in the molten metal can be achieved by controlling the speed of rotation of the rotating permanent magnets.
[00039] A non-contact metal flux inductor may include a series of permanent rotating magnets. The magnets can be integrated into a heat insulted non-ferromagnetic shield and can be located along a melt reservoir. The magnetic field created by the rotating permanent magnets acts on the molten metal under an oxide layer to generate the fluid flow conditions during casting. Magnetic fonts can be rotated using any suitable rotation mechanism. Examples of suitable rotation mechanisms include electric motors, fluid motors (eg hydraulic or pneumatic motors), adjacent magnetic fields (eg using an additional magnetic source to induce rotation of the magnetic source magnets), etc. Other suitable rotation mechanisms can be used. In some cases, a fluid engine is used to turn engines that use a coolant, such as air, allowing the same fluid to both cool the magnetic source and cause the magnetic source to rotate, such as through interaction with a turbine. or impeller. Permanent magnets can be rotatably free with respect to a central axis and induced to rotate about the central axis or permanent magnets can be rotatably fixed to a central rotating axis. In some non-limiting examples, permanent magnets can be rotated at about 10-1000 revolutions per minute (RPM) (such as 10 RPM, 25 RPM, 50 RPM, 100 RPM, 200 RPM, 300 RPM, 400 RPM, 500 RPM , 750 RPM, 1000 RPM or any value in between). Permanent magnets can be rotated at a speed in the range of about 50 RPM to about 500 RPM.
[00040] In some cases, frequency, intensity, location or any combination thereof of the varying magnetic field or fields generated on the surface of a melt reservoir can be adjusted based on visual inspection by an operator or camera. Visual inspection may include looking for disturbances or turbulence on the surface of the melt pool and may include looking for the presence of crystals impacting the surface of the melt pool.
[00041] In some cases, magnetically insulating materials (eg magnetic coating) may be placed between adjacent magnetic sources (eg adjacent non-contact melt flux inductors) to magnetically shield the adjacent magnetic sources from each other.
[00042] The melt reservoir can be circular, symmetrical or bilaterally unsymmetrical in shape. The shape and amount of metal flow inducers used along a particular melt reservoir can be dictated by the shape of the melt reservoir and desired flow of molten metal.
[00043] In a non-limiting example, a first set of permanent magnet assemblies can rotate in series with a second set of permanent magnet assemblies. The first and second sets of assemblies can be contained in a single compartment or separate compartments. The first set and the second set of assemblies may rotate out of phase (eg with unsynchronized magnetic fields) from each other, inducing linear flux in a single direction, such as along the long side of a rectangular ingot mold with inverted flow on the opposite side of the same rectangular ingot mold. Alternatively, assemblies can rotate in phase (eg with magnetic fields) synchronized with each other. Sets can rotate at the same speed or at different speeds. Assemblies can be powered by a single engine or separate engines. Assemblies can be powered by a single motor and are oriented to rotate at different speeds or in different directions. Assemblies may be evenly or unequally spaced above the casting sump.
[00044] Magnets can be integrated into a set at equally spaced or not equally spaced angular locations around the axis of rotation. Magnets can be integrated into an assembly at equal or different radial distances around the axis of rotation.
[00045] The axis of rotation of the assembly can be parallel to the level of molten metal to be agitated (eg by controlling the molten flow). The axis of rotation of the assembly can be parallel to isothermal solidification. The assembly's axis of rotation may not be parallel with the generally rectangular shape of a rectangular mold cavity. Other guidelines can be used.
[00046] Non-contact melt flow inducers can be used with mold cavities of any shape, including cylindrical forming ingot molds (eg as used to form ingots for forging or extrusion). Flow inducers can be oriented to generate the curvilinear flow of molten metal in one direction along the periphery of a cylinder-forming ingot mold. Flow inducers can be oriented to generate arc flow patterns that are different from the generally circular shape of the cylinder forming ingot mold.
[00047] Non-contact melt flow inducers can be oriented adjacent to each other about a single axis of rotation (eg centerline of a mold cavity) and can rotate in opposite directions to generate the adjacent opposite flows of the single axis of rotation. Adjacent opposing flows can create shear forces at the confluence of opposing flows. Such guidelines can be especially useful for large diameter ingots.
[00048] The multiple flow inducers can be oriented around non-collinear rotation axes and rotate in opposite directions, which generate fluid flows which in turn create non-cylindrical shear forces at the confluence of fluid flows.
[00049] Adjacent flux chokes can have parallel or non-parallel axes of rotation.
[00050] In some cases, non-contact melt flow inducers can be used in combination with flow directors. A flow director can be a submersible device within cast aluminum and positioned to direct the flow in a particular way. For example, non-contact molten flow inducers that direct flow near the surface of the molten metal towards the edges of a foundry can be paired with flow directors positioned close to - but farther away from - the solidification surface such that the solidification directors. flux direct flow from the solidifying surface (for example, prohibiting metal that begins to flow from the solidifying surface to flow toward the center of the metal reservoir until after it has flowed from a substantial portion of the solidifying surface).
[00051] In some cases, non-contact induced circular flow can distribute the macrosegregated intermetallics and/or partially solidified crystals distributed (eg iron) very evenly across the melt reservoir. In some cases, non-contact induced linear flow toward or opposite the long faces of the cast may distribute macrosegregated intermetallics (eg, iron) along the center of the cast product. Macrosegregated intermetallics directed to form along the center of the cast product may be beneficial in some circumstances, such as in aluminum foil products that must be bent.
[00052] In some cases, it may be desirable to induce the formation of intermetallic compounds of a particular size (eg large enough to induce recrystallization during hot rolling, but not large enough to cause failure). For example, in some cast aluminums, intermetallic compounds having a size of less than 1 µm in equivalent diameter are not substantially beneficial; Intermetallic compounds having a size greater than about 60 µm in equivalent diameter can be harmful and large enough to cause failures in the final level of a laminated sheet product after cold rolling. Thus, intermetallic compounds that have a size (equivalent diameter) of about 1-60 μm, 5-60 μm, 10-60 μm, 20-60 μm, 30-60 μm, 40-60 μm, or 50-60 μm µm may be desirable. Induced molten metal flow can help distribute intermetallic compounds around sufficiently so that these semi-large intermetallic compounds are able to form more easily.
[00053] In some cases, it may be desirable to induce the formation of intermetallic compounds that are easier to break down during hot rolling. Intermetallics that can be easily broken during rolling tend to occur more frequently with increased mixing or agitation, especially in stagnant regions such as corners and the center and/or bottom of the reservoir.
[00054] Increased mixing or agitation can be used to increase homogeneity within the molten reservoir and resulting ingot, such as by mixing crystals and heavy particles. Increased mixing or agitation can also move the crystals and heavier particles around the melt reservoir, slowing down the solidification rate and allowing alloying elements to diffuse along the metal's solidifying crystals. In addition, increased mixing or agitation can allow the formation of crystals to ripen faster and ripen longer (eg, due to delayed solidification speed).
[00055] The techniques described here can also be used to induce along a sympathetic flow of a molten metal reservoir. Due to the shape of the molten metal vessel and the properties of the molten metal, primary flow (eg induced flow directly onto the metal from the flux inducer) cannot reach the full depth of the molten vessel. Sympathetic flow (eg, secondary flow induced by primary flow), however, can be induced through proper placement and primary flow force, and can reach stagnant regions within the melt reservoir, such as those described above.
[00056] Ingot casting with the techniques described herein may have a uniform grain size, original grain size, intermetallic distribution along the outer surface of the ingot, the typical non-macrosegregation effect at the ingot center, accentuated homogeneity or any combination of same. Ingot casting using the techniques and systems described herein may have additional beneficial properties. A more uniform grain size and greater homogeneity can reduce or eliminate the need for grain refiners being added to molten metal. The techniques described here can create a larger mix without cavitation and without increased oxide generation. Increased mixing can result in a thinner liquid-solid interface within the solidifying ingot. In one example, during the casting of an aluminum ingot, if the liquid-solid interface is approximately 4 mm wide, it can be reduced by up to 75% or more (about 1 mm wide or less) when inductors Non-contact flux melters are used to agitate the molten metal.
[00057] In some cases, using the techniques described here can decrease the average grain size of a resulting melt and can induce relatively uniform size throughout the grain of the melt. For example, an aluminum ingot cast using the techniques disclosed here may only have grain sizes equal to or less than about 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, 400 μm, 420 μm, 440 μm, 460 μm, 480 μm or 500 μm, 550 μm, 600 μm, 650 μm or 700 μm. For example, an aluminum ingot cast using the techniques disclosed herein may have an average grain size equal to or less than about 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, 400 μm, 420 μm, 440 μm, 460 μm, 480 μm, 500 μm, 550 μm, 600 μm, 650 μm or 700 μm. Relatively uniform grain size may include maximum grain size standard deviations equal to or less than 200, 175, 150, 125, 100, 90, 80, 70, 60, 50, 40, 30, 20 or less. For example, a product foundry using the techniques disclosed herein may have a maximum grain size standard deviation or less than 45.
[00058] In some cases, the use of the techniques described herein may decrease dendritic spacing (for example, the distance between adjacent dendrite branches of dendrites in crystallized metals) in the resulting molten product and may induce relatively uniform arm spacing along the dendrite of the cast product. For example, an aluminum ingot cast using the non-contact melt flow inducers may have a dendritic mean spacing across the ingot of about 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm , 45 µm or 50 µm. The relatively uniform dendrite arm spacing may include a maximum standard deviation of dendrite spacing equal to or less than 16, 15, 14, 13, 12, 11, 10, 9, 8.5, 8, 7.5, 7, 6 .5, 6, 5.5, 5 or less. For example, a molded product having average dendritic spacing (eg, as measured at locations across the thickness of an ingot cast to a common cross section) of 28 µm, 39 µm, 29 µm, 20 µm and 19 µm may have a maximum standard deviation of dendritic spacing of approximately 7.2. For example, a product foundry using the techniques disclosed herein may have a maximum standard deviation of dendritic spacing equal to or less than 7.5.
[00059] In some cases, the techniques described here may allow for more precise control of macrosegregation (eg intermetallic compounds or where intermetallics collect). Increased control of intermetallics can allow for optimal grain structures to be produced in a cast product while starting with the cast material that has higher alloying content or higher recycled content, which would normally hamper the formation of grain structures. great. For example, recycled aluminum can generally have a higher iron content than new or prime aluminum. The more recycled aluminum used in a smelter, in general, the higher the iron content, the less cost intensive and additional time-consuming processing is done to dilute the iron content. With a higher iron content, it can sometimes be difficult to produce a desirable product (eg with small crystal sizes throughout and no undesirable intermetallic structures). However, increased control of intermetallics, such as using the techniques described here, can allow the leakage of desirable products, even with cast metal with a high iron content, such as 100% recycled aluminum. The use of 100% recycled metals can be highly desirable for environmental and other business needs.
[00060] In some cases, non-contact flux inductors may include magnetic sources that have elements to protect the radiant heat transfer magnets and conductor, such as a radiant heat reflector and/or a low thermal conduction material. Magnetic sources can include a coating with low thermal conductivity (eg, a refractory coating or an airgel) such as to inhibit conductive heat transfer. Magnetic sources can include a metal shield, such as a polished metal shell (for example, to reflect radiative heat). Magnetic sources can additionally include a cooling mechanism. If desired, a heat sink can be associated with the magnetic source to dissipate heat. In some cases, a coolant (eg, water or air) may be forced around or through the magnetic source to cool the magnetic source. In some cases, shielding and/or cooling mechanisms can be used to keep the temperature of the magnets down so that the magnets do not become demagnetized. In some cases, magnets may incorporate shielding and/or porous metals such as MuMetals to shield and/or reorient magnetic fields away from equipment and/or a sensor that may be adversely affected by the magnetic fields generated by the magnets.
[00061] Permanent magnets placed adjacent to each other along a central axis can be oriented to have offset poles. For example, the north poles of sequential magnets can be offset approximately 60° from adjacent magnets. Other deflection angles can be used. Alternating poles can limit resonance in the molten metal due to magnetic circulation of the molten metal. Alternatively, adjacent magnet poles are not compensated. In cases where permanent magnets are not used, the generated magnetic fields can be scaled to achieve a similar effect.
[00062] As the one or more magnetic sources create variable magnetic fields, they can induce fluid flow in any molten metal below the magnetic sources in a direction generally perpendicular to the central axes of the magnetic sources (eg, axes of rotation for a permanent magnet of magnetic source rotation). The central axis (eg axis of rotation) of a magnetic source can be generally parallel to the surface of the molten metal.
[00063] The concepts disclosed can be used in monolithic or multilayer casting (for example, simultaneous casting of coated ingots), where rotating magnets can be used to control the flow of molten metal fluid away from or towards the interface between the different types of molten metal. The concepts described can be used with molds of any shape, including but not limited to rectangular, circular and complex shapes (eg, ingots formed for extrusion or forging).
[00064] In some cases, the one or more magnetic sources may be coupled to a height adjustment mechanism that can be used to raise and lower the one or more magnetic sources with respect to the mold. During the casting method, it may be desirable to maintain a uniform distance between the one or more magnetic sources and the upper surface of the molten metal. The height adjustment mechanism can adjust the height of one or more magnetic sources if the top surface of the molten metal increases or decreases. The height adjustment mechanism can be any suitable mechanism for adjusting the distance between the one or more magnetic sources and the top surface (for example, if the difference is changed). The height adjustment mechanism may include sensors capable of detecting changes in the height of the top surface. The height adjustment mechanism can detect metal levels, such as changes in metal levels referenced from a point on the joint upper surface. The one or more magnetic sources can be suspended by cables, chains or other suitable devices. The one or more magnetic sources can be coupled to a trough above the mold and/or coupled to the mold itself.
[00065] In some cases, the use of one or more magnetic sources as disclosed herein can assist in normalizing the temperature of the molten metal, such as during the initial stage where non-standard temperatures can make starting the melt more difficult.
[00066] In some cases, the use of one or more magnetic sources, as disclosed herein, can help in the distribution of molten metal to all corners between the mold walls. Such distribution can help eliminate the meniscus effect (eg, a small difference of 0.5 to 6 millimeters) at these corners. This distribution can be achieved during the initial phase by generating fluid flow from molten metal to the mold walls.
[00067] In some cases, one or more magnetic sources may be positioned inside or around the mold walls or any other suitable location in relation to the molten metal. In a non-limiting example, the one or more magnetic sources are positioned adjacent to the meniscus. In another non-limiting example, one or more magnetic sources are positioned approximately above the center of the upper surface of the molten metal.
[00068] Several non-contact flux inducers can be used at different times. Adjusting the timing of the generation of varying magnetic fields can provide the desired results at different points in time during the casting method. For example, no field could be generated at the beginning of the casting method, a strong magnetic field change could be generated in a first direction during a first portion of the casting method, and a weak oscillating magnetic field could be generated in an opposite direction during a second portion. of the casting method. Other timing variations can be used.
[00069] In addition, the use of one or more magnetic sources in the meniscus can modify the structures of the grains. Grain structures can thus be modified through forced convection. Grain structures can be modified by exciting the velocity of molten metal at the solid/liquid interface (eg, by forcing hot metal from the top surface down to the solidification interface). Such an effect can be enhanced through the use of flow administration as described herein.
[00070] Certain other aspects and features of the present invention pertain to the use of an alternating magnetic field to control the migration of molten metal oxide onto the molten metal surface, such as during casting (eg casting an ingot , billet or brick). Alternating magnetic fields can be introduced using rotating permanent magnets or electromagnets, as described here. The alternating magnetic field can be used to push or otherwise induce metal oxide movement in a desired direction, such as to a meniscus at the beginning of casting, to the center during steady state casting, and to the meniscus at the end of casting. casting, thus minimizing metal oxide rollover in the middle portion of the molten metal ingot and concentrating any oxide formation at the ends of the molten metal. The alternating magnetic field can further be used to deform the meniscus and to guide the metal oxide during the non-melting method, such as during filtration and degassing of molten metal. Eddy currents produced on the upper surface of the molten metal can additionally inhibit the meniscus effect, helping the molten metal to reach any corners where the mold walls meet.
[00071] During molten metal processing, movement, and casting, metal oxide layers can form on the surface of the molten metal. Metal oxide is generally undesirable as it can clog filters and lead to defects in a molten product. The use of a non-contact magnetic source to control metal oxide migration allows for greater control of metal oxide accumulation and movement. The metal oxide can be directed to the intended locations (eg, moving away from a filter that the metal oxide can clog and to a metal oxide pathway having a different removal filter and/or an operator location for safely remove metal oxides). Non-contact magnetic sources can be used to generate the alternating magnetic fields that cause eddy currents (eg metal flux) to form on or near the upper surface of the molten metal, which can be used to orient the supported metal oxide through the upper surface of the molten metal in a desired direction. Examples of suitable magnetic sources include those described herein with reference to flow control devices.
[00072] Magnetic sources can be rotated using any suitable rotation mechanism. In some cases, permanent magnets can be rotated at around 60-3000 revolutions per minute.
[00073] Permanent magnets placed adjacent to each other along a central axis can be oriented to have offset poles as described here. The alternating pole can limit resonance in the molten metal due to the magnetic circulation of the molten metal. Oxide generation due to molten metal movement can likewise be limited through the use of alternating poles.
[00074] As the one or more magnetic sources create alternating magnetic fields, they can induce eddy currents (eg metal flux) in any molten metal below the magnetic sources in a direction generally perpendicular to the central axes of the sources (eg rotation axes for a magnetic source rotating permanent magnet). The central axis (eg axis of rotation) of a magnetic source can be generally parallel to the surface of the molten metal.
[00075] In the casting method, molten metal can be introduced into a mold by a distributor. A skimmer can optionally be used to trap some metal oxide in a region immediately around the dispenser. One or more magnetic sources can be positioned between the manifold and the mold walls to generate eddy currents on the surface of the molten metal that are sufficient to control and/or induce the migration of metal oxide along the surface of the molten metal . Each magnetic source can generate an alternating magnetic field (eg from rotating permanent magnets) that induces eddy currents in directions normal to the mold wall opposite the magnetic source from the distributor (eg along a line from from the distributor to the wall). The use of multiple magnetic sources can allow metal oxide migration to be controlled in various ways and directions, including collecting the metal oxide at the center of the upper surface (eg, near the distributor) and thus inhibiting it. to approach the meniscus from the upper surface (eg adjacent where the upper surface meets the mold walls). Metal oxide migration can also be controlled to push metal oxide away from the distributor and towards the upper surface meniscus.
[00076] In some cases, a casting method may include an initial phase, a steady state phase and a final phase. During the initial phase, the liquid metal is first introduced into the mold and the first few inches (eg, five to ten inches) of molten metal are formed. This portion of molten metal is sometimes referred to as the bottom or base of molten metal, which can be removed and discarded. After the initial stage, the casting method reaches a steady state stage in which the middle portion of the molten metal is formed. As used in this document, the term "steady state phase" may refer to any stage of execution of the casting method, in which the middle portion of the molten metal is formed, regardless of any acceleration or lack of acceleration in the casting speed. After the steady state phase, the final phase occurs where the upper part of the molten metal is formed and the casting method is completed. As the base of molten metal, the top of molten metal (or ingot head) can be removed and discarded.
[00077] In some cases, the metal oxide migration can be controlled, so that the metal oxide is directed to the upper surface meniscus during the initial phase and optionally during the final phase. During the steady state phase, however, metal oxide can be directed outward from the upper surface meniscus. As a result, any metal oxide formed in the molten metal will be concentrated at the bottom and/or top of the molten metal, both of which can be removed and discarded, resulting in a mid-portion of the molten metal ingot having minimal of metal oxide buildup. Metal oxide can be directed to the meniscus during the initial phase to leave more space on the upper surface during the steady state phase. Metal oxide can be directed to the meniscus during the final stage to spread the metal oxide that has been collected on the upper surface (for example, so that the metal oxide is incorporated into the shortest space of a segment of the molten metal possible).
[00078] In some cases, the alternating magnetic field is started about a minute after the molten metal enters the mold. The alternating magnetic field can continue during the initial phase until the zenith of the metal level is reached, at which point the alternating magnetic field can reverse directions to direct the metal oxide away from the meniscus and towards the center of the upper surface of the cast metal.
[00079] The disclosed concepts can be used in monolithic or multilayer casting (for example, simultaneous casting of coated ingots), where rotating magnets can be used to direct the oxide away from the interface between different types of molten metal. The concepts described can be used with molds of any shape, including rectangular, circular and complex shapes (eg ingots formed for extrusion or forging).
[00080] In some cases, the one or more magnetic sources may be positioned above the upper surface of the molten metal and just between the manifold and the mold walls that form the bearing sides of the molten metal (for example, those sides that are in contact with working rollers during rolling). In other cases, one or more magnetic sources are positioned above the upper surface of the molten metal and between the manifold and all mold walls.
[00081] In some cases, one or more magnetic sources may be positioned inside or around the mold walls or any other suitable location in relation to the molten metal. In some cases, the one or more magnetic sources are positioned adjacent to the meniscus. In other cases, the one or more magnetic sources are positioned approximately above the center of the upper surface of the molten metal.
[00082] In some cases, the one or more magnetic sources can generate alternating magnetic fields adjacent to the meniscus to deform the meniscus, such as increasing or decreasing the height of the meniscus with respect to the height of the remaining portion of the upper surface of the molten metal . Increasing the height of the meniscus can help prevent metal oxide rollover by acting as a physical barrier to displacement and can be helpful during the steady state phase. Decreasing the height of the meniscus can help allow the metal oxide to shift more easily, which can be used during the initial and/or final phase.
[00083] In some cases, non-contact magnetic sources can simultaneously and/or selectively act as flux inducers and metal oxide controllers, as described in this document. In some cases, a flow inducer can be positioned closer to the molten metal to induce deeper metal flow, while a metal oxide controller is positioned further away from the molten metal to induce shallower metal flow (by example, eddy currents).
[00084] These illustrative examples are given to introduce the reader to the general matter discussed in this document and are not intended to limit the scope of the concepts disclosed. The following sections describe various additional features and examples with reference to the figures, in which like numerals indicate like elements and directional descriptions are used to describe illustrative embodiments, but like illustrative embodiments, they should not be used to limit the present disclosure. Elements included in the illustrations in this document may be drawn out of scale.
[00085] FIG. 1 is a partial cross-sectional view of a metal casting system 100 without flow inducers, in accordance with certain aspects of the present disclosure. A metal source 102, such as a funnel, can supply molten metal to a feed tube 104. A skimmer 108 can be used throughout the feed tube 104 to help distribute molten metal and reduce the production of metal oxides. on the upper surface of the molten reservoir 110. A lower block 120 can be lifted by a hydraulic cylinder 122 to reach the walls of the mold cavity 112. As the liquid metal begins to solidify within the mold, the lower block 120 can be lowered. The molten metal 116 may include sides 118 that have solidified, while the molten metal added to the mold may be used to continuously extend the molten metal 116. In some cases, the walls of the mold cavity 112 define a hollow space and may contain a liquid cooling 114, such as water. Cooling fluid 114 may jet out of the hollow space and flow down sides 118 of molten metal 116 to help solidify molten metal 116. The ingot being molten may include a solidified metal region 128, a transition metal region 126 and a molten metal region 124.
[00086] When no flow inducers are used, the molten metal leaving the distributor 106 flows in a pattern generally indicated by the flow lines 134. The molten metal may only flow approximately 20 millimeters below the distributor 106 before returning to the surface. The flow lines 134 of the molten metal generally lie close to the surface of the molten vessel 110, not reaching the middle and lower portions of the molten metal region 124. Therefore, the molten metal in the middle and lower portions of the molten metal region 124, especially in the areas of the molten metal region 124 adjacent to the transition metal region 126, they are not well mixed.
[00087] As described above, due to the preferential sedimentation of the crystals formed during the solidification of the molten metal, a stagnation region 130 of crystals may occur in the middle portion of the region 124 of molten metal. The accumulation of these crystals in the stagnation region 130 can cause problems in ingot formation. The stagnation region 130 can reach solids fractions of up to about 15% to about 20%, although other values outside the range are possible. Without the use of flow inducers, molten metal does not flow well (eg, see flow lines from 134) to the stagnation region 130 and thus crystals that may form in the stagnation region 130 if accumulate and are not mixed over the entire region of the molten metal 124.
[00088] Furthermore, as alloying elements are rejected from the crystals that form at the solidification interface, they can accumulate in a stagnation region of low position 132. Without the use of flow inducers, the molten metal does not flow well ( for example, see flow lines 134) to the low position stagnation region 132 and thus the crystals and heavier particles within the low position stagnation region typically do not mix well along the metal region cast 124.
[00089] In addition, crystals from an upper stagnation region 130 and the low position stagnation region 132 may fall toward and gather near the bottom of the reservoir, forming a central bulge 136 of solid metal at the bottom of the region. of transition metal 126. This central protuberance 136 can result in undesirable properties in the molten metal (e.g., an undesirable concentration of alloying elements, intermetallic compounds, and/or an undesirable large grain structure). Without the use of flow inducers, molten metal does not flow (eg, see flow lines 134) low enough to displace and mix these crystals and particles that have accumulated near the bottom of the reservoir.
[00090] FIG. 2 is a top view of a metal casting system 200 that uses flow inducers 240 in a lateral orientation, in accordance with certain aspects of the present disclosure. The 240 flux inductors are non-contact casting flux inductors that use rotating permanent magnets. Other non-contact melt flow inducers can be used, such as electromagnetic flux inducers.
[00091] The mold cavity 212 is configured to contain the molten metal 210 within a set of long walls 218 and short walls 234. Although the mold cavity 212 is shown to be rectangular in shape, any other cavity shape is shown. mold can be used. Molten metal 210 is introduced into mold cavity 212 through manifold 206. An optional skimmer 208 can be used to collect some metal oxide that may form as molten metal exits manifold 206 into the mold cavity. 212.
[00092] Each flux inductor 240 may include one or more magnetic sources. Flow inducers 240 may be positioned adjacent to and above surface 202 of molten metal 210. Although four flow inducers 240 are illustrated, any suitable number of flow inducers 240 may be used. As described above, each flow inducer 240 may be used. be positioned above surface 202 in any suitable way, including by suspension. Magnetic sources in flux inductors 240 can include one or more permanent magnets that can rotate about axes of rotation 204 to generate a variable magnetic field. Electromagnets can be used instead of or in addition to permanent magnets to generate the alternating magnetic field.
[00093] The flow inducers 240 can be positioned on opposite sides of a mold centerline 236 with their axes of rotation 204 parallel to the mold centerline 236. The flow inducers 240 situated to one side of the mold centerline 236 (e.g., on the left side, as seen in FIG. 2) can rotate in a first direction 246 to induce metal flow 242 toward the centerline of mold 236. Flow inducers 240 located on the opposite side of the centerline of mold 236 (e.g., the right side as seen in Fig. 2) may rotate in a second direction 248 to induce metal flow 242 toward the centerline of mold 236. Interaction between metal flows 242 on sides Opposites of the mold centerline 236 can generate increased mixing within the molten metal 210, as described herein.
[00094] Flow inducers 240 can be rotated in other directions to induce metal flow 242 in other directions. Flow inducers 240 may be located in different directions than having axes of rotation 204 parallel to the centerline of mold 236 or parallel to each other.
[00095] FIG. 3 is a cross-sectional diagram of the metal casting system 200 of FIG. 2, taken through lines A-A, in accordance with certain aspects of the present disclosure. Molten metal flows from metal source 302 to feed tube 304 and out of manifold 206. The metal in mold cavity 212 may include a solidified metal region 328, a transition metal region 326, and a molten metal region 324.
[00096] Two flow inducers of 240 are seen above the surface 202 of the molten reservoir 306. One flow inducer 240 rotates in a first direction 246, while the other rotates in a second direction 248. Rotation of the flow inducers 240 induces flow molten 242 in molten metal 342 of molten reservoir 306. Molten flow 242 induced by flow inducers 240 induces sympathetic flow 334 throughout molten reservoir 306. Sympathetic flow 334 throughout molten reservoir 306 can provide increased mixing and may prevent the formation of stagnation regions. Furthermore, due to increased thermal homogeneity, the metal transition region 326 may be smaller or thinner than when no flux inducers 240 are being used. Flow inducers 240 can agitate the molten metal 210 sufficiently to decrease the width of the metal transition region 326 by up to 75% or more. For example, if the width of the metal transition region 326 would normally be about 4 millimeters or any other suitable width, the use of flux inducers as described in this document can reduce that width to less than about 4mm such as, but not limited to less than 3mm or less than 1mm or less.
[00097] FIG. 4 is a top view of a metal casting system 400 that utilizes flow inducers 440 in a radial orientation, in accordance with certain aspects of the present disclosure. The 440 flux inductors are non-contact casting flux inductors that use rotating permanent magnets. Other non-contact melt flow inducers can be used, such as electromagnetic flux inducers.
[00098] The mold cavity 412 is configured to contain the molten metal 410 within a set of long walls 418 and short walls 434. Although the mold cavity 412 is shown to be rectangular in shape, any other cavity shape is mold can be used. Molten metal 410 is introduced into mold cavity 412 through feed tube 406. An optional skimmer 408 can be used to collect some metal oxide that may form as molten metal exits feed tube 406 to the mold cavity 412.
[00099] Each flux inducer 440 may include one or more magnetic sources. Flow inducers 440 may be positioned adjacent to and above surface 402 of molten metal 410. Although four flow inducers 440 are illustrated, any suitable number of flow inducers 440 may be used. As described above, each flow inducer 440 may be used. be positioned above the top surface 402 in any suitable way, including by suspension. Magnetic sources in flux inductors 440 can include one or more permanent magnets that can rotate about axes of rotation 404 to generate a variable magnetic field. Electromagnets can be used instead of or in addition to permanent magnets to generate the alternating magnetic field.
[000100] The flow inducers 440 can be positioned around the feed tube 406 and oriented to induce the metal flow 442 in a generally circular direction. As can be seen in FIG. 4, rotation of the flow inducers 440 in the direction 446 induces metal flow 442 in a generally clockwise direction. Flow inducers 440 can be rotated in the opposite direction 446 to induce metal flow in a generally counterclockwise direction. Rotating metal flow 442 can generate increased mixing within molten metal 410, as described herein. Flow inducers 440 may be located in different orientations than shown.
[000101] In some cases, sufficient circular or rotational flow can be induced to form a vortex.
[000102] FIG. 5 is a top view of a metal casting system 500 that uses flux inductors 540 disposed in a longitudinal orientation, in accordance with certain aspects of the present disclosure. The 540 flux inductors are non-contact casting flux inductors that use rotating permanent magnets. Other non-contact melt flow inducers can be used, such as electromagnetic flux inducers. The 540 flux inducers are shown housed in a first set 550 and a second set 552.
[000103] The mold cavity 512 is configured to contain the molten metal 510 within a set of long walls 518 and short walls 534. mold can be used. Molten metal 510 is introduced into mold cavity 512 through feed tube 506. An optional skimmer 508 can be used to collect some metal oxide that may form as molten metal exits feed tube 506 to the mold cavity 512.
[000104] Each flux inductor 540 may include one or more magnetic sources. Each flux inductor 540 can be positioned adjacent to and above the top surface 502 of the molten metal 510. Although sixteen flux inductors 540 are illustrated covering two 550,552 assemblies, any suitable number of flow inductors 540 and 550,552 assemblies can be used. As described above, each flux inducer 540 may be positioned above the top surface 502 in any suitable manner, including by suspension. Magnetic sources in flux inductors 540 may include one or more permanent magnets rotatable about rotational axes to generate alternating magnetic field. Electromagnets can be used instead of or in addition to permanent magnets to generate the alternating magnetic field.
[000105] Each assembly 550, 552 can be oriented laterally over mold cavity 512, generally parallel to long walls 518 and positioned between long walls 518 and feed tube 506. Flow inducers 540 can induce metal flow 542 in a generally circular direction. As seen in FIG. 5, Rotation of flow inducers 540 in direction 546 induces metal flow 542 in a generally counterclockwise direction. Flow inducers 540 can be rotated in a direction opposite to direction 546 to induce metal flow in a generally clockwise direction. Rotating metal flow 542 can generate increased mixing within molten metal 510, as described herein. Flow inductors 540 and assemblies 550, 552 may be located in orientations other than those shown.
[000106] Each flux inductor 540 can be operated out of phase with the adjacent flux inductor 540 (eg with magnetic poles of a permanent magnet that rotates at 90°,60°, 180° or other amounts of magnet deviation adjacent permanent property). Operating adjacent flux chokes 540 out of phase with each other can control the harmonic frequency and wave amplitude created in the molten metal 510.
[000107] FIG. 6 is a close-up, cross-sectional elevation view of the flux inducer 240 of FIGs. 2 and 3, in accordance with certain aspects of the present disclosure. Flow inducer 240 may be rotated in direction 246 to induce molten flow 242 in molten metal from molten reservoir 306. molten flow 242 can generate sympathetic flow 334 of molten metal deeper into molten reservoir 306, as described herein.
[000108] As illustrated, a flux inductor 240 may include an outer casing 602. The outer casing 602 may be a radiant heat reflector such as a polished metal casing or any other suitable radiant heat reflector. The flux inducer 240 may additionally include a conductive heat inhibitor 604. The conductive heat inhibitor 604 may be any suitable low thermal conduction conductive material, such as a refractory material or an airgel or any other low conduction conductive material thermal.
[000109] The flux inductor 240 may additionally include a casing in the middle 606 that separates the permanent magnets and the conductive heat inhibitor 604. One or more permanent magnets 608 may be positioned around an axis 614.
[000110] In some cases, permanent magnets 608 can be rotationally free with respect to axis 614. Permanent magnets 608 can be positioned around an inner layer 610 that is rotationally free with respect to axis 614 through the use of brackets 612 .
[000111] Other types and arrangements of magnetic sources can be used.
[000112] FIG. 7 is a top view of a metal casting system 700 that utilizes flow inducers 740 in a radial orientation within a circular mold cavity 712, in accordance with certain aspects of the present disclosure. The 740 flux inductors are non-contact casting flux inductors that use rotating permanent magnets. Other non-contact melt flow inducers can be used, such as electromagnetic flux inducers.
[000113] The circular mold cavity 712 is configured to contain the molten metal 710 within a single circular wall 714. Although the mold cavity is shown to be circular in shape, any other mold cavity shape, any number of walls can be used. Molten metal 710 is introduced into mold cavity 712 through feed tube 706. Metal casting system 700 is shown without the optional skimmer.
[000114] Each flux inducer 740 may include one or more magnetic sources. Flow inducers 740 may be positioned adjacent to and above surface 702 of molten metal 710. Although four flow inducers 740 are illustrated, any suitable number of flow inducers 740 may be used. As described above, each flow inducer 740 may be used. be positioned above the top surface 702 in any suitable way, including by suspension. Magnetic sources in flux inductors 740 can include one or more permanent magnets that can rotate about axes of rotation 704 to generate a variable magnetic field. Electromagnets can be used instead of or in addition to permanent magnets to generate the alternating magnetic field.
[000115] The flow inducers 740 can be positioned around the feed tube 706 and oriented to induce the metal flow 742 in a generally circular direction. Axes of rotation 704 of flow inducers 740 may be positioned on (e.g., collinear with) radii extending from the center of mold cavity 712. As seen in FIG. 7, rotation of flow inducers 740 in the direction 746 induces metal flow 742 in a generally counterclockwise direction. Flow inducers 740 can be rotated in the opposite direction 746 to induce metal flow in a generally clockwise direction. Rotating metal flow 742 can generate increased mixing within molten metal 710, as described herein. The 740 flux inducers may be located in different orientations than shown.
[000116] FIG. 8 is a schematic diagram of a flux inductor 800 that contains permanent magnets in accordance with certain aspects of the present disclosure. Flux inductor 800 includes a housing 802 and permanent magnets 804. Permanent magnets 804 are rotatably attached to a shaft 806. Shaft 806 can be driven by a motor or in any other suitable way.
[000117] In some cases, an impeller 808 can be rotatably fixed on the shaft 806. As a coolant is forced into the flow inducer 800 towards 810, the coolant can pass along the impeller 808, causing shaft 806 to rotate, which causes permanent magnets 804 to rotate. In addition, the coolant will continue to flow down the flux inductor 800, passing over or near the permanent magnets 804, cooling them. Examples of suitable coolant include air or other gases or liquids.
[000118] As can be seen in FIG. 8, adjacent permanent magnets 804 may have rotationally shifted (eg, staggered) north poles. For example, the north poles of sequential magnets can be offset approximately 60° from adjacent magnets. Other deflection angles can be used. Alternating poles can limit resonance in the molten metal due to magnetic circulation of the molten metal. In other cases, adjacent magnet poles are not deflected.
[000119] FIG. 9 is a top view of a metal casting system 900 using corner flow inductors 960 at the corners of mold cavity 912, in accordance with certain aspects of the present disclosure. The 960 corner flux inductors are non-contact cast flux inductors that use rotating permanent magnets. Other non-contact melt flow inducers can be used, such as electromagnetic flux inducers.
[000120] The mold cavity 912 is configured to contain the molten metal 910 within a set of long walls 918 and short walls 934. A corner exists where the wall meets an adjacent wall. Although mold cavity 912 is shown to be rectangular in shape and having 90° corners, any other shape of mold cavity can be used with any number of corners, with any angular amplitude. Molten metal 910 is introduced into mold cavity 912 through feed tube 906. An optional skimmer 908 can be used to collect some metal oxide that may form as molten metal exits feed tube 906 to the mold cavity 912.
[000121] Corner flux inductors 960 may include one or more magnetic sources to generate varying magnetic fields. A corner flux inductor 960 can include a turntable 966 coupled to a motor 962 by a shaft 964. Optionally, the turntable can be rotated by other mechanisms. The rod may be supported by a bracket 970. The bracket 970 may be mounted to the walls of the mold cavity 912 or otherwise positioned adjacent to the mold cavity 912. The turntable 966 may include one or more permanent magnets 968, which are positioned radially beyond the axis of rotation 974 of the turntable 966. The axis of rotation 974 of the turntable 966 may be slightly inclined toward the surface of the molten metal 910, such that the rotation of the turntable 966 (eg, in direction 972) will sequentially move the one or more permanent magnets 968 toward and away from the molten metal surface 910 near the corner of mold cavity 912, generating a variable magnetic field at the corner of the mold cavity. mold 912. In other cases, corner flux inductors 960 may include electromagnetic sources to generate varying magnetic fields at the corners of mold cavities 912.
[000122] Rotation of turntables 966 in direction 972 can induce molten flow 942 in molten metal through corner 910 (eg, generally clockwise flow through corner). For example, rotation of turntables 966 as depicted in FIG. 9, can induce molten flow 942 from the left side of each corner flux inducer 960, through the corner, and out after the right side of each corner flux inducer 960, as seen by looking at the flux inducer 960 of feed tube 906. Rotation in the opposite direction may induce molten flow in the opposite direction.
[000123] FIG. 10 is an axonometric view depicting a corner flux inducer 960 of FIG. 9 in accordance with certain aspects of the present disclosure. Corner flow inductor 960 includes a bracket 970 that is secured to the walls of mold cavity 912. A motor 962 drives a shaft 964 that rotates turntable 966 in direction 972. Optionally, turntable can be rotated by other mechanisms . Permanent magnets 968 are mounted on rotating plate 966 to rotate together with rotating plate 966. Rotating plate 966 rotates about an axis of rotation 974 which is inclined toward the surface of molten metal 910. In alternative cases, the axis of rotation 974 is not inclined but is quite parallel to the surface of the molten metal 910.
[000124] As the rotary plate 966 rotates, one of the permanent magnets 968 begins to move closer to the surface of the molten metal 910 while the other of the permanent magnets 968 begins to move away from the surface of the molten metal 910. As the first of the permanent magnets 968 is rotated to its closest point to the surface of the molten metal 910, the other of the permanent magnets 968 is at its point furthest from the surface of the molten metal 910. The rotation continues to bring about the other of the permanent magnets 968 toward the surface of the molten metal 910, as the first of the permanent magnets 968 is rotated away from the surface of the molten metal 910.
[000125] The floating distances of the permanent magnets 968 from the surface of the molten metal 910 generate a variable magnetic field, which induces the molten flux 942 a of the molten metal 942 through the corner. For example, the rotation of the turntable 966, as shown in FIG. 10 can induce molten flow 942 from the left side of the corner, through the corner, and out of the right side of the corner. Rotation in the opposite direction can induce molten flow in the opposite direction.
[000126] FIG. 11 is an enlarged cross-sectional view of a flow inducer 1100 used with a flow director 1120, in accordance with certain aspects of the present disclosure. The flux inducer 1100 may be similar to the flux inducer 240 of FIG. 2 or it can be any other suitable flux inducer (eg with other types and arrangements of magnetic sources). Flow inducer 1100 may be rotated in direction 1116 to induce molten flow 1122 in the molten metal of molten reservoir 1118. The molten flow 1122 may pass over flow conductor 1120 and continue at solidification interface 1124.
[000127] Flow director 1120 can be made of any material suitable for submersion in molten metal 1118. Flow director 1120 can be wing-shaped or otherwise shaped to induce flow down the solidification interface 1124 ( for example, to increase the flux in the low position stagnation region near the 1124 solidification interface and/or to aid in the metallic crystal maturation method). The 1120 flow director can extend to any suitable depth within the reservoir.
[000128] In some cases, the flow director 1120 is coupled to the mold body 1126, such as by means of movable arms (not shown). In some cases, the flow director 1120 is coupled to a conveyor (not shown) which optionally also carries the flow inducer 1100. In this way, the distances between the flow inducer 1100 and the flow director 1120 can be kept constant. In some cases, the movable arms (not shown) engage the flow director 1120 for the conveyor or the mold body 1126 may allow the flow director 1120 to move (e.g., for positioning within the molten reservoir 1118 and /or for insertion/removal from/into the molten vessel 1118).
[000129] FIG. 12 is a cross-sectional diagram of a metal casting system 1200 using a multi-part flow inducer that employs Fleming's Law for molten metal flow in accordance with certain aspects of the present disclosure. The multi-part flux inductor includes at least one magnetic field source 1226 (e.g., a part of permanent magnets) and a pair of electrodes. By the simultaneous application of an electric current and a magnetic field through the molten metal 1208, force can be induced in the molten metal perpendicular to the directions of the electric current and the magnetic field.
[000130] Molten metal flows from the metal source 1202 to the feed tube 1204 and out of the manifold 1206. The metal in the mold cavity 1212 may include a solidified metal region 1214, a transition metal region 1216 and a region of cast metal 1218.
[000131] The 1226 magnetic field sources can be located anywhere suitable to induce a magnetic field through at least a portion of the molten metal region 1218. In some cases, the 1226 magnetic field sources may include static permanent magnets , permanent rotating magnets or any combination thereof. In some cases, the magnetic field sources of 1226 may be positioned in, over, or around mold cavity 1212.
[000132] The electrode pair may be coupled to a 1230 controller. A lower electrode 1224 may contact the solidified metal region 1214 as the molten product is lowered. Bottom electrode 1224 can be any electrode suitable for slidingly contacting the solidified metal region 1214. In some cases, the lower electrode 1224 is a brush-shaped electrode, such as an electroplating brush. In some cases, the top electrode may be a 1220 electrode incorporated in the 1206 manifold. In some cases, the top electrode may be a 1222 electrode that is submersible in the 1208 molten metal.
[000133] FIG. 13 is a top view of a mold 1300 during a steady state stage of casting in accordance with certain aspects of the present disclosure. As used herein, a 1300 mold is a form of molten metal container. Mold 1300 is configured to contain molten metal 1304 within walls 1302 of mold 1300. As seen in FIG. 13 from the top of the page and moving in a clockwise direction, walls 1302 include a first wall, a second wall, a third wall, and a fourth wall around molten metal 1304. A meniscus 1328 of molten metal 1304 is present beside walls 1302 of mold 1300. Molten metal 1304 is fed into mold 1300 by dispenser 1306. An optional skimmer 1308 can be used to collect some metal oxide that may form as molten metal exits the dispenser 1306 to mold cavity 1300.
[000134] One or more magnetic sources, such as magnetic sources 1310, 1312, 1314, 1316, are positioned above the upper surface 1340 of the molten metal 1304. Although four magnetic sources are illustrated, any suitable number of magnetic sources can be used, including more or less than four. As described above, magnetic sources 1310, 1312, 1314, 1316 can be positioned above top surface 1340 in any suitable way, including by suspension. Magnetic source 1310 includes one or more permanent magnets that can rotate around axis 1338 to generate an alternating magnetic field. Electromagnets can be used instead of or in addition to permanent magnets to generate the alternating magnetic field. Magnetic source 1310 can be rotated in direction 1330 to induce eddy currents in molten metal 1304 in direction 1318. Likewise, magnetic sources 1312, 1314, 1316 can be similarly constructed and positioned and rotated in directions 1332, 1334, 1336, respectively, to generate eddy currents in the molten metal in directions 1304 1320, 1322, 1324, respectively. By means of the collective eddy currents induced in the molten metal 1304 in the directions 1318, 1320, 1322, 1324, metal oxide 1326 supported by the upper surface 1340 of the molten metal 1304 is directed to the dispenser 1306 at the center of the upper surface 1340. This control of 1326 metal oxide helps prevent the 1326 metal oxide from rolling over the 1328 meniscus.
[000135] FIG. 14 is a cross-sectional view of the mold 1300 of FIG. 13 taken along line B-B, during the steady-state phase, in accordance with certain aspects of the present disclosure. A hopper 1402 can deliver molten metal through a manifold 1306. Optional skimmer 1308 can be used around manifold 1306. During an initial phase, lower block 1420 can be lifted by hydraulic cylinder 1422 to meet walls 1302 of mold 1300. As the molten metal begins to solidify within the mold, the lower block 1420 can be lowered. The molten metal 1404 can include sides 1412, 1414 and 1416 that have solidified, while the molten metal added to the mold can be used to continuously extend the molten metal 1404. The molten metal portion 1404 is formed first (e.g., the proximal lower portion to block 1420) is known as the bottom or end of molten metal 1404 which can be removed and discarded after molten metal 1404 has been formed.
[000136] Meniscus 1328 is seen on top surface 1340 adjacent to walls 1302. In some cases, walls 1302 may define a hollow space and may contain a coolant 1410, such as water. Cooling fluid 1410 may jet out of the hollow space and flow through sides 1412, 1414 of molten metal 1404 to help solidify molten metal 1404. Third solidified side 1416 of molten metal 1404 is seen in FIG. 14. The third side 1416 includes metal oxide inclusions 1418 near the bottom of the molten metal 1404. As described above, the metal oxide may have been induced to roll over the meniscus 1328 during the initial phase, which causes the metal oxide inclusions 1418 form near the bottom of the molten metal 1404. Because the casting method 1300 is seen in a steady state phase in FIG. 14, there are minimal metal oxide inclusions 1418 being formed on the sides of the molten metal 1404 due to rotation of magnetic sources 1310, 1312, 1314, 1316.
[000137] FIG. 15 is a cross-sectional view of the mold 1300 of FIG. 13 taken along line C-C during the final stage of casting, in accordance with certain aspects of the present disclosure. The cross-sectional view shows molten metal 1404 being composed of molten metal 1304, solidified metal 1504, and transition metal 1502. Transition metal 1502 is the metal that is between the molten and solidified states.
[000138] Meniscus 1328 is seen on top surface 1340 adjacent to walls 1302. In some cases, walls 1302 define a hollow space and may contain a coolant 1410, such as water. Cooling fluid 1410 may jet out of the hollow space and flow through sides 1412, 1414 of molten metal 1404 to help solidify molten metal 1404.
[000139] During the final phase of casting, the magnetic sources 1310, 1312, 1314, 1316 can rotate in opposite directions from which they rotate during the steady state phase. For example, magnetic sources 1312, 1316 can rotate in directions 1506, 1508, respectively, to create eddy currents on top surface 1340 in directions 1510, 1512, respectively. These eddy currents can help to propel metal oxide toward meniscus 1328 so that metal oxide can roll over it. Magnetic sources 1310, 1312, 1314, 1316 can also be rotated in these same directions during the initial phase of casting.
[000140] FIG. 16 is a close-up view of a magnetic source 1316 above molten metal 1304 in accordance with certain aspects of the present disclosure. Magnetic source 1316 may be the same or similar to flux inducer 240 of FIG. 6 and may include any variations as described above. Magnetic source 1316 can be rotated in direction 1336 to induce eddy currents on top surface 1340 of molten metal 1304 in direction 1324. Eddy currents can help inhibit metal oxide 1326 on top surface 1340 from reaching and rolling over meniscus 1328, by orienting metal oxide 1326 toward the center of molten metal 1304.
[000141] FIG. 17 is a top view of the mold 1300 of FIG. 13 during an initial casting phase in accordance with certain aspects of the present disclosure. Mold 1300 contains molten metal 1304 within walls 1302 of mold 1300.
[000142] During the initial phase of the casting, the magnetic sources 1310, 1312, 1314 and 1316 can rotate in the directions 1702, 1704, 1706 and 1708, respectively, to induce eddy currents in the molten metal 1304 in the directions 1710, 1712, 1714 and 1716, respectively. These eddy currents can propel metal oxide 1326 towards meniscus 1328, causing it to roll over it.
[000143] FIG. 18 is a top view of an alternative mold 1800 in accordance with certain aspects of the present disclosure. Mold 1800 includes a complex wall 1802. Molten metal 1804 is introduced into mold 1800 by a manifold 1808. One or more magnetic sources 1806 are positioned between manifold 1808 and wall 1802 to control the migration of metal oxide along the upper surface of molten metal 1804 (eg, to inhibit and/or induce metal oxide rolling over meniscus 1810) as desired.
[000144] In cases with complex walls 1802, the complex shape of walls 1802 may include curves 1812 (eg curves inwards or outwards). Magnetic fountains 1806 may be positioned around curves 1812 so that the axis of each magnetic fountain 1806 is approximately perpendicular to the shortest line between the center of magnetic fountain 1806 and walls 1802 (e.g., parallel to the longer portion. close to the wall). Such an arrangement may allow the 1806 magnetic sources to induce eddy currents that are directed towards or away from the wall.
[000145] FIG. 19 is a schematic diagram of a magnetic source 1912 adjacent to a molten metal meniscus 1906, in accordance with certain aspects of the present disclosure. Magnetic source 1912 can be located within walls 1908 of a mold 1900. Mold 1900 can include a strip of graphite 1910 used to form a primary solidification layer of the molten metal. A meniscus 1906 can be located adjacent where the upper surface 1902 of the molten metal 1904 meets the walls 1908.
[000146] Under normal conditions (eg without the use of a 1912 magnetic source adjacent to the 1906 meniscus), the 1906 meniscus may have a 1918 curve, which is generally flat. In cases where a 1912 magnetic source is adjacent to the 1906 meniscus, the 1912 magnetic source may induce a change in the height of the 1906 meniscus. When the 1912 magnetic source rotates in the 1914 direction, the 1906 meniscus may be raised and may follow the 1920 curve When the 1912 magnetic source rotates in a direction opposite to the 1914 direction, the 1906 meniscus can be raised and can follow the 1916 curve.
[000147] When meniscus 1906 is raised to curve 1920, meniscus 1906 can provide a physical barrier to the displacement of metal oxide rolling on top surface 1902, which can be advantageous during the steady state phase of casting. When meniscus 1906 is lowered to curve 1916, meniscus 1906 can provide a reduced barrier to metal oxide displacement on top surface 1902, which can be advantageous during the initial stage and/or the final stage of casting.
[000148] In some cases, magnetic fountain 1912 within walls 1908 may be cooled using a coolant (not shown), such as water, already present and/or flowing through walls 1908.
[000149] In some cases where the 1912 magnetic source is rotating in a direction opposite to the 1914 direction, the grain structure of the resulting molten metal can be changed by adjusting the speed with which the 1904 molten metal approaches the solid/ liquid (not shown).
[000150] FIG. 20 is a top view of a chute 2002 for conveying molten metal 2004 in accordance with certain aspects of the present disclosure. As used in this document, a 2002 gutter is a type of cast metal container. One or more 2006 magnetic sources are positioned above the top surface of the 2004 molten metal to control the migration of metal oxide 2008 along the top surface of the 2004 molten metal. As the one or more 2006 magnetic sources create alternating magnetic fields, they induce eddy currents in molten metal 2004 in a direction perpendicular to its center axes (eg, axes of rotation for a rotating permanent magnet magnetic source). Eddy currents can divert the 2008 metal oxide through an alternative path from the 2002 gutter, such as to a 2010 collection area.
[000151] Metal oxides 2008 in the 2010 collection zone can be filtered manually or automatically. In some cases, the 2010 collection area may reconnect to the main route of the 2002 chute.
[000152] In some cases, the 2006 magnetic source can be positioned to deflect 2008 metal oxide as the 2004 molten metal moves between a degasser and a filter. By diverting the 2008 metal oxides to a 2010 collection area for removal, the 2004 molten metal can be processed through the filter without premature clogging and/or filter clogging by the 2008 metal oxides.
[000153] FIG. 21 is a flowchart describing a casting method 2100 in accordance with certain aspects of the present disclosure. Casting method 2100 may include a first stage 2102 followed by a steady state stage 2104, followed by a final stage 2106, as described in more detail above.
[000154] During initial phase 2102, it may be desirable to direct metal oxide towards the sides of the forming molten metal (eg, stimulate metal oxide displacement). During initial phase 2102, one or more magnetic sources adjacent to an upper surface of the molten metal can direct metal oxide to the meniscus in block 2108. If desired, during initial phase 2102, one or more magnetic sources adjacent to the meniscus can reduce the meniscus in block 2110.
[000155] During the steady state phase 2104, it may be desirable to direct the metal oxide away from the sides of the forming molten metal (eg inhibit metal oxide displacement), collecting the metal oxide on the metal surface molten to final stage 2106. During steady-state phase 2104, one or more magnetic sources adjacent to an upper surface of the molten metal can direct metal oxide away from the meniscus in block 2112. If desired, during steady-state phase 2104, one or more magnetic sources adjacent to the meniscus can lift the meniscus at block 2114.
[000156] During final stage 2106, it may be desirable to direct metal oxide towards the sides of the forming molten metal (eg stimulate metal oxide displacement). During final stage 2106, one or more magnetic sources adjacent to an upper surface of the molten metal may direct metal oxide to the meniscus in block 2116. If desired, during final stage 2106, one or more magnetic sources adjacent to the meniscus may reduce the meniscus in block 2118.
[000157] In various examples, one or more of the blocks 2108, 2110, 2112, 2114, 2116, 2118 disclosed above may be omitted from their respective phases in any combination.
[000158] The modalities and examples described in this document allow the migration of metal oxide to be better controlled on the surface of the molten metal.
[000159] Various flux inducers used in various orientations have been described in this document for induction of melt flux and control of metal oxides. Although examples of certain flow inducers and orientations are given with reference to the figures contained herein, it will be understood that any combination of the flow inducers and any combination of placement or orientation of the flow inducer can be used together to achieve the desired results ( eg mixing, metal oxide control or any combination thereof). As a non-limiting example, corner flux inducers 960 of FIG. 9 can be used with the flux inducers 240 of FIG. 2 to produce a desired molten flow.
[000160] The description provided in this document allows for non-contact molten flow control of molten metal. The flow control described in this document can allow the casting of ingots that have a more desirable crystal structure and that have more desirable properties for downstream rolling or other processing.
[000161] The foregoing description of modalities, including illustrated modalities, has been presented for illustration and description purposes only and is not intended to be exhaustive or to limit disclosure to the precise forms disclosed. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art.
[000162] As used below, any reference to a series of examples shall be understood to refer to each of these examples (for example, "Examples 1-4" shall be understood as "Examples 1, 2, 3 or 4" ).
[000163] Example 1 is an apparatus comprising a mold for accepting molten metal; and at least one non-contact flux inducer positioned above a surface of the molten metal to generate a variable magnetic field in proximity to the surface of the molten metal which is sufficient to induce molten flux in the molten metal.
[000164] Example 2 is the apparatus of example 1, wherein the at least one non-contact flux inducer includes a first non-contact flux inducer positioned in front of a mold centerline from and parallel with a second inductor of non-contact flow.
[000165] Example 3 is the apparatus of examples 1 or 2, wherein the at least one non-contact flow inducer is positioned close to a mold corner to induce molten flow through the mold corner.
[000166] Example 4 is the apparatus of example 3, wherein the at least one non-contact flux inducer includes a plurality of permanent magnets positioned on a rotating plate that rotates around an axis of rotation.
[000167] Example 5 is the apparatus of examples 1-4, wherein the at least one non-contact flux inducer comprises at least one permanent magnet rotating around an axis.
[000168] Example 6 is the apparatus of example 5, in which the axis is positioned parallel to a central line of the mold.
[000169] Example 7 is the apparatus of example 5, in which the axis is positioned along a radius that extends from a center of the mold.
[000170] Example 8 is a molten metal product using the apparatus of examples 1-7.
[000171] Example 9 is a method comprising introducing molten metal into a mold cavity; generating a variable magnetic field near an upper surface of the molten metal; and inducing molten fluid in the molten metal by generating the variable magnetic field.
[000172] Example 10 is the method of example 9, which further comprises the induction of sympathetic flow in molten metal by induction of molten flow.
[000173] Example 11 is the method of example 10, wherein sympathetic flux induction comprises sufficient sympathetic flux induction to mix the molten metal and reduce a thickness of a transitional metal region to approximately less than 3 millimeters.
[000174] Example 12 is the method of example 10, wherein sympathetic flow induction comprises sufficient sympathetic flow induction to mix the molten metal and reduce a thickness of a transitional metal region to approximately less than 1 millimeter.
[000175] Example 13 is the method of examples 9-12, wherein the induction of molten flow includes inducing a first molten flow towards a centerline of the mold cavity; and inducing a second molten flow towards the centerline of the mold and in a direction opposite to the first molten flow.
[000176] Example 14 is the method of examples 9-13, wherein the melt flow inducer includes inducing the melt flow in a generally circular direction.
[000177] Example 15 is the method of examples 9-14, wherein the induction of melt flow includes inducing the melt flow through a corner of the mold cavity.
[000178] Example 16 is a metal product casting using the method of examples 9-15.
[000179] Example 17 is a system comprising a mold for receiving molten metal; a non-contact flux inducer positioned directly above a surface of the molten metal; and a magnetic source included in the non-contact flux inducer for generating a variable magnetic field sufficient to induce molten flux under the surface of the molten metal.
[000180] Example 18 is the system of example 17, in which the magnetic source includes at least one permanent magnet that rotates around a rotational axis at a speed between about 10 revolutions per minute and about 500 revolutions per minute.
[000181] Example 19 is the system of examples 17 or 18, in which the non-contact flow inducer is oriented to induce molten flow in a direction parallel to a mold wall.
[000182] Example 20 is the system of examples 17-19, in which the non-contact flow inducer is oriented to induce molten flow in a direction perpendicular to a radius extending from a center of the mold.
[000183] Example 21 is an apparatus comprising a mold for receiving molten metal; and at least one magnetic source positioned above the mold for generating an alternating magnetic field near a surface of a molten metal that is sufficient to direct movement of metal oxides over the surface of the molten material.
[000184] Example 22 is the apparatus of example 21, wherein the at least one magnetic source comprises at least one permanent magnet rotating around an axis.
[000185] Example 23 is the apparatus of example 22, wherein the at least one magnetic source comprises a plurality of permanent magnets arranged in a Halbach matrix.
[000186] Example 24 is the apparatus of examples 22 or 23, wherein the at least one magnetic source further comprises a radiant heat reflector and a conductive heat inhibitor around the at least one permanent magnet.
[000187] Example 25 is the apparatus of examples 21-24, further comprising a height adjustment mechanism coupled to at least one magnetic source to adjust a distance between the at least one magnetic source and the surface of the molten metal.
[000188] Example 26 is the apparatus of examples 21-25, further comprising one or more magnetic sources to generate one or more additional alternating magnetic fields sufficient to generate one or more eddy currents on the surface of the molten metal sufficient to inhibit displacement of metal oxides.
[000189] Example 27 is a method comprising introducing molten metal into a container; generating an alternating magnetic field near an upper surface of the molten metal; and directing the metal oxide onto the upper surface of the molten metal by generating the alternating magnetic field.
[000190] Example 28 is the method of example 27, in which the generation of the alternating magnetic field comprises the rotation of one or more permanent magnets about an axis.
[000191] Example 29 is the method of examples 27 or 28, wherein introducing molten metal into the container comprises filling a mold and wherein directing the metal oxide comprises inhibiting the displacement of metal oxides by directing of the metal oxide to migrate towards a center of the mold.
[000192] Example 30 is the method of example 29, wherein filling the mold comprises at least an initial phase and a steady state phase; where displacement inhibition occurs during the steady state phase; and wherein metal oxide targeting further comprises stimulating the displacement of metal oxides by targeting metal oxide to migrate towards the mold edges during the initial phase.
[000193] Example 31 is the method of examples 27-30, which further comprises generating a second alternating magnetic field in the vicinity of a meniscus of the upper surface of the molten metal; and adjusting a meniscus height based on the generation of the second alternating magnetic field.
[000194] Example 32 is the method of example 31, wherein introducing molten metal into the receptacle comprises filling a mold; wherein mold filling comprises at least an initial phase and a steady state phase; and wherein adjusting the height of the meniscus comprises increasing the height of the meniscus during the steady state phase.
[000195] Example 33 is the method of example 32, wherein adjusting the height of the meniscus further comprises decreasing the height of the meniscus during the initial phase.
[000196] Example 34 is the method of examples 27-33, further comprising adjusting a height of the alternating magnetic field in response to vertical movement of the upper surface of the molten metal.
[000197] Example 35 is a system comprising a non-contact magnetic source positionable adjacent to an upper surface of the molten metal for generating an alternating magnetic field suitable for controlling metal oxide migration along the upper surface and a coupled controller to the non-contact magnetic source to control the alternating magnetic field.
[000198] Example 36 is the system of example 35, in which the non-contact magnetic source comprises one or more permanent magnets rotatably mounted around one or more axes and in which the controller is operable to control the rotation of one or more permanent magnets on one or more axes.
[000199] Example 37 is the system of example 35 or 36, in which the non-contact magnetic source can be positionable adjacent to an upper surface meniscus to deform the meniscus.
[000200] Example 38 is the system of examples 35 or 36, in which the non-contact magnetic source can be positioned above the upper surface of the molten metal and between a wall of a mold and a distributor of molten metal.
[000201] Example 39 is the system of example 38, in which the non-contact magnetic source is adjustable in height to selectively space the non-contact magnetic source a desired distance from the upper surface of the molten metal.
[000202] Example 40 is the system of examples 38 or 39, in which the alternating magnetic field is oriented to control the migration of metal oxide along the upper surface in a direction normal to the mold wall.
[000203] Example 41 is an aluminum product having a crystal structure with a maximum standard deviation of dendritic arm spacing equal to or less than 16, the aluminum product obtained by introducing molten metal into a mold cavity and by induction of molten flux in molten metal by generating a variable magnetic field near the upper surface of the molten metal.
[000204] Example 42 is the aluminum product of example 41, in which the maximum standard deviation of spacing of the dendritic arms is equal to or less than 10.
[000205] Example 43 is the aluminum product of example 41, in which the maximum standard deviation of spacing of the dendritic arms is equal to or less than 7.5.
[000206] Example 44 is the aluminum product of examples 41-43, in which the average spacing of the dendritic arms is equal to or less than 50 μm.
[000207] Example 45 is the aluminum product of examples 41-43, in which the average spacing of the dendritic arms is equal to or less than 30 µm.
[000208] Example 46 is the aluminum product of examples 41-45, wherein the induction of molten flux in the molten metal further includes the induction of sympathetic flux in the molten metal.
[000209] Example 47 is an aluminum product having a crystal structure with a maximum standard deviation of grain size equal to or less than 200, the aluminum product obtained by introducing molten metal into a mold cavity and by induction of molten flux in molten metal by generating a proximate variable magnetic field near an upper surface of the molten metal.
[000210] Example 48 is the aluminum product of example 47, where the maximum grain size standard deviation is equal to or less than 80.
[000211] Example 49 is the aluminum product of example 47, where the maximum grain size standard deviation is equal to or less than 45.
[000212] Example 50 is the aluminum product of examples 47-49, where the average grain size is equal to or less than 700 µm.
[000213] Example 51 is the aluminum product of examples 47-49, where the average grain size is equal to or less than 400 µm.
[000214] Example 52 is the aluminum product of examples 47-51, wherein the induction of molten flux in the molten metal further includes the induction of sympathetic flux in the molten metal.
[000215] Example 53 is the aluminum product of examples 47-52, where the maximum standard deviation of the dendritic arm spacing is or is below 10.
[000216] Example 54 is the aluminum product of example 47-52, where the maximum standard deviation of the dendritic arm spacing is or is below 7.5.
[000217] Example 55 is the aluminum product of examples 47-52, where the average spacing of the dendritic arm is or is below 50 µm.
[000218] Example 56 is the aluminum product of examples 47-52, where the average spacing of the dendritic arm is or is below 30 µm.

权利要求:
Claims (6)
[0001]
1. Method of metal casting, characterized in that it comprises the steps of: introducing molten metal (1304, 1804, 1904) into a container, which step of introducing molten metal (1304, 1804, 1904) into a container comprises filling of a mold (1300, 1800, 1900), where the filling of the mold (1300, 1800, 1900) comprises at least an initial phase and a steady state phase; generating an alternating magnetic field near an upper surface (1340, 1902) of the molten metal (1304, 1804, 1904); and, directing the metal oxide (1326) onto the upper surface (1340, 1902) of the molten metal (1304, 1804, 1904) by generating the alternating magnetic field, where the step of directing the metal oxide (1326) comprises the inhibition of metal oxide displacement by directing metal oxide (1326) toward a center of the mold (1300, 1800, 1900), where displacement inhibition occurs during the steady state phase; and, where the step of directing the metal oxide (1326) further comprises stimulating the displacement of the metal oxides by directing the metal oxide (1326) to migrate towards the mold edges (1300, 1800, 1900) during the early stage.
[0002]
2. Method according to claim 1, characterized in that the alternating magnetic field generation comprises the rotation of one or more permanent magnets about an axis (1338).
[0003]
3. Method according to claim 1, characterized in that it further comprises the steps of: generating a second alternating magnetic field near a meniscus (1328) of the upper surface (1340, 1902) of the molten metal (1304, 1804, 1904 ); and, adjusting a height of the meniscus (1328) based on the generation of the second alternating magnetic field.
[0004]
4. Method according to claim 3, characterized in that adjusting the height of the meniscus (1328) comprises increasing the height of the meniscus (1328) during the steady state phase.
[0005]
5. Method according to claim 4, characterized in that adjusting the height of the meniscus (1328) further comprises decreasing the height of the meniscus during the initial phase.
[0006]
6. The method of claim 1, further comprising the step of: adjusting a height of the alternating magnetic field in response to the vertical movement of the upper surface (1340, 1902) of the molten metal (1304, 1804, 1904) .

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法律状态:
2019-08-20| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2020-11-10| B07A| Application suspended after technical examination (opinion) [chapter 7.1 patent gazette]|

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2021-03-09| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-05-04| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 21/05/2015, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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US201462001124P| true| 2014-05-21|2014-05-21|

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US62/001,124|2014-05-21|

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US201462060672P| true| 2014-10-07|2014-10-07|

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US62/060,672|2014-10-07|

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PCT/US2015/032026|WO2015179677A1|2014-05-21|2015-05-21|Non-contacting molten metal flow control|

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