Process measurement and control and material characterization in remelting furnaces

Abstract

The magnetic field components measured around and along the remelt furnace and other measured furnace parameters are used to estimate the concentricity of the electrodes in the furnace crucible, to estimate the distribution of drip shorts across the gap between the electrodes and the molten pool, or to detect, locate, and categorize anomalous events during the remelt process. They may be used to control the operation of the furnace during the remelt process or incorporated into the resulting longitudinal or three-dimensional map of the ingot. Artificial intelligence, machine learning, or neural networks may be employed.

Description

Technical Field

[0001] Priority Claim This application claims priority to (i) U.S. Provisional Application No. 63 / 326,799, filed Apr. 1, 2022, in the name of Cibula et al., entitled "Process measurement and control and material characterization in a remelting furnace", (ii) U.S. Provisional Application No. 63 / 409,203, filed Sep. 22, 2022, in the name of Cibula et al., entitled "Characterization of vacuum arc remelting with a high-density magnetic field sensor array", and (iii) U.S. Non-Provisional Application No. 18 / 129,816, filed Mar. 31, 2023, in the name of Cibula et al., entitled "Process measurement and control and material characterization in a remelting furnace", all of which are hereby incorporated by reference in their entirety.

[0002] The field of the present invention relates to remelting furnaces. In particular, devices and methods for process measurement and control and material characterization in remelting furnaces are described herein.

Brief Description of the Drawings

[0003] [Figure 1] FIG. 1 is a schematic perspective view of an exemplary configuration of a magnetic sensor coupled to a computer system. [Figure 2] FIG. 2 is a schematic longitudinal cross-sectional view of an exemplary configuration of a remelting furnace with a magnetic sensor. [Figure 3] FIG. 3 is a schematic longitudinal cross-sectional view of an exemplary configuration of a remelting furnace with a magnetic sensor. [Figure 4]Figures 4A, 4B, and 4C are schematic isometric, plan, and side views of exemplary configurations of magnetic sensors and magnetic sources coupled to a computer system. [Figure 5] Figure 5 is a schematic longitudinal cross-sectional view of an exemplary configuration of a remelting furnace having a magnetic sensor and a magnetic source. [Figure 6] Figure 6 is a schematic side view of an exemplary configuration of a magnetic sensor and magnetic source. [Figure 7] Figures 7A and 7B are schematic side views of exemplary configurations of a fixed magnetic sensor and a movable magnetic source. [Figure 8] Figures 8A and 8B are schematic side views of exemplary configurations of a movable magnetic sensor and a movable magnetic source. [Figure 9] Figure 9 is a schematic side view of an exemplary configuration of a magnetic sensor and magnetic source. [Figure 10] Figure 10 is a schematic side view of an exemplary configuration of a movable magnetic sensor. [Figure 11] Figures 11A and 11B are schematic longitudinal cross-sectional views of an exemplary configuration of a remelting furnace with a movable magnetic sensor, before (Figure 11A) and after (Figure 11B), during the remelting process. [Figure 12] Figures 12A and 12B are schematic longitudinal cross-sectional views of exemplary configurations of a remelting furnace with a movable magnetic sensor, before (Figure 12A) and after (Figure 12B), during the remelting process. [Figure 13] Figures 13A and 13B are schematic longitudinal cross-sectional views of exemplary configurations of a remelting furnace having a fixed magnetic sensor and a movable magnetic sensor, before (Figure 13A) and after (Figure 13B), during the remelting process. [Figure 14] Figures 14A and 14B are schematic longitudinal cross-sectional views of exemplary configurations of a remelting furnace having a movable magnetic sensor and a movable magnetic source, before (Figure 14A) and after (Figure 14B), during the remelting process. [Figure 15]Figures 15A and 15B are schematic longitudinal cross-sectional views of an exemplary configuration of a remelting furnace having actuators and movable magnetic sensors, before (Figure 15A) and after (Figure 15B), during the remelting process. [Figure 16] Figures 16A and 16B are schematic longitudinal cross-sectional views of an exemplary configuration of a remelting furnace having actuators, a movable magnetic sensor, and a movable magnetic source, before (Figure 16A) and after (Figure 16B) the remelting process. [Figure 17] Figures 17A and 17B are schematic longitudinal cross-sectional views of an exemplary configuration of a remelting furnace having actuators and movable magnetic sensors, before (Figure 17A) and after (Figure 17B), during the remelting process. [Figure 18] Figures 18A and 18B are schematic longitudinal cross-sectional views of an exemplary configuration of a remelting furnace having actuators, a movable magnetic sensor, and a movable magnetic source, before (Figure 18A) and after (Figure 18B) the remelting process. [Figure 19] Figure 19 is a diagram that includes a plot of the simulated longitudinal magnetic field component as a function of the longitudinal position along the furnace, calculated using different transverse positions of the electrodes in the furnace and the current segment in the gap. [Figure 20] Figure 20 is a diagram that includes a plot of the measured magnetic field components as a function of the transverse position of the electrodes in the furnace. [Figure 21] Figure 21 is a diagram containing plots of measured current, voltage, and magnetic field components during transverse movement of electrodes within the furnace. [Figure 22] Figure 22 shows the measured drip short distribution for two different remelting processes. [Modes for carrying out the invention]

[0004] The illustrated embodiments are illustrative only, and not all features may be shown in full detail or in appropriate proportions. For clarity, some features or structures may be exaggerated or reduced in scale or omitted entirely. Drawings should not be considered to be at a constant scale unless expressly indicated as such. The illustrated embodiments are illustrative and should not be construed as limiting the scope of this disclosure or the appended, subsequently presented claims.

[0005] The following embodiments for carrying out the invention should be read with reference to the drawings, where equivalent reference numerals refer to similar elements across different figures. The drawings are not necessarily to a fixed scale and illustrate selective examples, not limiting the scope of the invention. The embodiments for carrying out the invention illustrate the principles of the invention as examples, not limitations.

[0006] The subject matter disclosed herein may relate to the subject matter disclosed in one or more of the following, all of which are incorporated herein by reference: (i) U.S. Patent No. 8,111,059, (ii) U.S. Patent No. 10,514,413, (iii) U.S. Patent No. 10,761,116, (iv) U.S. Patent No. 11,022,656, (v) U.S. Patent No. 11,236,404, (vi) U.S. Patent No. 11,243,273, (vii) U.S. Patent No. 11,459,627, or (viii) U.S. Patent Application Publication No. 2022 / 0154300.

[0007] The references listed above disclose apparatus and methods for estimating and / or controlling the position and / or length of an electric discharge or arc, or other transversely localized electric current segment 30, flowing longitudinally across a gap 115 between two conductive bodies 110 and 120 (as in the various examples schematically shown in Figures 1 to 17B). Multiple magnetic field sensors 201 (fixed) and / or 202 (movable) are employed to measure the magnetic field components resulting from the current segment 30, and a computer system 299 is used to calculate the estimated position based on their measured magnetic field components and the corresponding locations where they were measured. A magnetic field source 300 may be employed to cause transverse movement of the current segment 30, and the magnetic field source 300 and the magnetic field sensors 201 / 202 may be coupled in a feedback configuration or as a servo mechanism to apply a control magnetic field based on the estimated location of the current segment 30. A longitudinal mechanical actuator 130 of any suitable type or configuration (e.g., hydraulic, gear-driven, servo motor, etc.) may be employed to control the distance between the conductive body 110 and the conductive body 120, and thus the length of the current segment 30. The longitudinal actuator 130 and magnetic field sensors 201 / 202 may be coupled in a feedback configuration or as a servo mechanism to move one or both conductive bodies 110 / 120 based on the estimated length of the current segment 30.

[0008] Such apparatus and methods can be usefully employed in a variety of settings. One important setting is in the field of a remelting furnace 100, in which current flows through a conductive metal electrode 110 to be melted, through an ingot 120 formed from molten metal from the electrode 110 that drips into a melt pool 122 on its upper surface, and through one or more localized current segments 30 spanning the gap 115 between the electrode 110 and the ingot 120. In some furnaces 100 (for example, a vacuum arc remelting furnace, also called a VAR furnace), the current segment 30 is an electrical discharge or arc, and the gap 115 is a vacuum or at best a diffuse plasma generated by the discharge or arc. In other furnaces 100, a gaseous medium occupies the gap 115 between the electrode 110 and the ingot 120. Furthermore, in other furnaces 100 (for example, electroslag remelting furnaces, also known as ESR furnaces), molten slag (not shown) occupies the gap 115 between the electrode 110 and the ingot 120. In any of these examples, the localized current segments 30 may also include transient short circuits (called drip shorts) through droplets of molten metal dripping across the gap 115 between the melting electrode 110 and the growing ingot 120. The location or distribution of any or all types of localized current segments 30, as well as other measured or observed behaviors or parameters during the remelting process, may be strongly correlated with the quality of the metal in the ingot 120 resulting from that remelting process. Accordingly, the methods and apparatus disclosed herein and in incorporated references may be advantageously employed, for example, to modify, maintain or otherwise control a remelting process, to evaluate the quality of the metal in the ingot 120 obtained by the remelting process, to guide the subsequent use, handling or processing of the metal in the ingot 120, or for other purposes.

[0009] A typical configuration of a fixed magnetic field sensor 201 is shown in Figure 1. The sensor 201 is configured around the periphery of a current-containing volume 10 (for example, the internal volume of a remelting furnace 100), through which current generally flows in the longitudinal direction. The sensor 201 measures the magnetic field component in two transverse dimensions in some examples, or in all three spatial dimensions (more commonly) in other examples. The sensor 201 is positioned at multiple different longitudinal locations along the volume 10 and / or at multiple different circumferential locations around the volume 10, corresponding to the sensor positions. In the example in Figure 1, the sensor 201 is configured as three rings of sensor 201 at three different longitudinal locations along the volume 10, as well as additional sensors 201 at other longitudinal locations, and other suitable sensor configurations may be employed. The sensor 201 is coupled to a computer system 299, which receives electronic signals from the sensor 201 indicating the measured magnetic field component. Based on one or more of the measured magnetic field components, the corresponding position of the sensor 201, and the corresponding calibration coefficient for the sensor 201, the computer system 299 can calculate the estimated transverse position or estimated transverse distribution of the current flowing through volume 10. This distribution can take the form of one or more localized current segments 30 within the gap 115 (e.g., electrical discharge or drip short in a VAR furnace), or a less localized current distribution within the electrode 110 and ingot 120. The computer system 299 can also calculate the estimated longitudinal positions of one or more localized current segments 30 within volume 10, which correspond to the longitudinal locations within volume 10 of the gap 115 between the electrode 110 and the ingot 120 (moving upward through the crucible 101 during the remelting process).These calculations may be performed in any suitable manner (e.g., analytical, numerical, approximate, etc.) based on Maxwell's equations or any suitable subset or adaptation thereof (e.g., Biot-Savart law or Jeffimenco's equations). Note that "one or more measured magnetic field components," "two or more measured magnetic field components," "multiple measured magnetic field components," "a portion of the measured magnetic field components," "all of the measured magnetic field components," etc., may refer to components in multiple different directions all measured at a single corresponding sensor location, components in all single directions measured at multiple corresponding sensor locations, or components in multiple different directions measured at multiple different corresponding sensor locations.

[0010] Figures 2 and 3 schematically show an example of a remelting furnace 100, which includes a crucible 101, an outer wall 102, and a water-cooled cooling jacket 103 between them. Sensors 201 are configured around the furnace 100 on the outside of the outer wall 102. Metal electrodes 110 in the upper part of the furnace 100 and metal ingots 120 in the crucible 101 in the lower part of the furnace are separated by a gap 115. Current 20 flows through the electrodes 110, across the gap 115 (for example, as an arc or discharge 30 in a VAR furnace, or (one or more) other localized current segments 30), through the ingots 120, and through the crucible 101 and the upper part of the furnace 100; alternatively, in these and subsequent examples, the current can instead flow through the crucible 101 in the lower part of the furnace 100. In some cases, a portion of the current may flow directly between the electrode 110 and the crucible 101 as a so-called side arc 32 (for example, as in Figure 3), which is undesirable as it can lead to damage to the furnace 100 or introduce impurities or contaminants into the ingot 120. The heat generated by the current 20 in the gap 115 during the remelting process causes the electrode 110 to melt and shrink and the ingot 120 to grow as the molten metal drips from the electrode 110 into the molten pool 122 at the top of the ingot 120. The gap 115 moves upward through the furnace 100 during the remelting process as the ingot 120 grows. Since the electrode 100 has a diameter smaller than the diameter of the ingot 120, the electrode 110 is lowered into the furnace 100 during the remelting process, maintaining a relatively constant distance across the gap 115. A longitudinal actuator for that purpose exists in all examples, but is only explicitly shown in Figures 15A to 18B (as actuator 130), and will be further described below.

[0011] In some cases, the estimated position of the current segment 30 can be recorded as a function of the longitudinal position of the gap 115, which corresponds to the longitudinal position along the solidified ingot 120 resulting from the remelting process. In some cases, the measured magnetic field component indicates the presence of a side arc 32 and, in some cases, the transverse location of the side arc 32 (e.g., along the circumference of the furnace). This side arc information can be recorded as a function of the longitudinal position of the gap 115 within the furnace 100, i.e., the longitudinal position along the ingot 120, and in some cases, as a function of the circumferential position around the furnace 100, i.e., the circumferential position around the ingot 120.

[0012] Instead of passively recording the arc position or side arc occurrence as a function of the longitudinal position along the ingot 120, or in addition to this, active measures may be taken during the remelting process in response to the measured magnetic field component. In some cases, the detection of a side arc 32, or the duration of a side arc 32 longer than a selected time limit, or the occurrence of multiple side arcs 32 exceeding a selected threshold number or within a selected time window, may cause the computer system 299 to, for example, change or interrupt the current 20, change the voltage, or move or retract the electrode 110. In some cases, the interruption or change may be temporary, after which the remelting process can continue as before; in some cases, the change may persist for as long as the remelting process can continue; and in some cases, the remelting process may be completely terminated.

[0013] In some examples, the magnetic field source 300 may be positioned around the arc furnace 100 and configured to enable changing, maintaining, or controlling the transverse position of the current segment 30 within the gap 115. The general configuration of the source 300 and the sensor 201 is schematically shown in FIGS. 4A - 4C, where a pair of conductive coils 300x is configured to apply a magnetic field along the x - direction and a second pair of coils 300y is configured to apply a magnetic field along the y - direction. Both the source 300 (i.e., the coils 300x / 300y) and the sensor 201 are operably coupled to a computer system 299. The computer system 299 can be structured and programmed to cause current to flow through the coils 300x and / or 300y in response to the magnetic field measured by the sensor 201 (i.e., in response to the estimated position of the current 20 flowing through the current - containing volume 10). The source 300 and the sensor 201 and / or 202 can be coupled to each other by the computer system 299 in a feedback configuration or as a servo mechanism, and thus, a magnetic field is applied by the source 300 to change, maintain, or control the position of the current 20 in response to the magnetic field measured by the sensor 201 / 202. In some examples, the magnetic field can be applied by the source 300 to produce a desired transverse trajectory or transverse distribution of the current 20. FIGS. 5 - 9 show various exemplary configurations of the source 300 and the sensor 201 on the remelting furnace 100 (including the moving source 300 in FIGS. 7A / 7B and FIGS. 8A / 8B, and the moving sensor 202 in FIGS. 8A / 8B).

[0014] < In the example described above, the longitudinal actuator moves the electrode 110 downward as it melts away, maintaining a relatively constant distance across the gap 115 (since the diameter of the electrode 110 is smaller than the diameters of the crucible 101 and the ingot 120, the electrode 110 shrinks faster than the ingot 120 grows during the remelting process). In some examples, this can be achieved by, for example, monitoring the weight of the electrode 110 (which decreases as the electrode 110 melts), monitoring the voltage drop across the gap 115, or monitoring the rate of drip shorts, each of which is loosely correlated with at least the distance across the gap 115 and the length of the current segment 30 spanning the gap 115.

[0015] Figure 10 schematically shows a typical configuration of a movable magnetic field sensor 202 that moves longitudinally along a current-containing volume 10. Figures 11A to 16B schematically show various examples of a remelting furnace 100 with movable sensors 202. The movable sensors 202 are generally spaced closer together than fixed sensors 201. An actuator of any preferred type or configuration (e.g., hydraulic, gear-driven, servo motor, etc.) is configured to move the sensors 202 and coupled to a computer system 299, so that the sensors 202 can generally be moved in response to the magnetic field component measured by those sensors 202 in order to keep the sensors 202 close to the gap 115 as they move along the volume 10, and a feedback configuration or servo mechanism coupling the sensor actuator and the sensors 202 can be implemented by the computer system 299 for that purpose. The computer system 299 may be structured and programmed to calculate an estimated length parameter that characterizes the current segment 30 (and thus also characterizes the separation between conductors 110 and 120 across the gap 115), the calculation of which is at least partially based on the magnetic field components measured by sensors 201 and / or 202. In some examples, the length parameter may be recorded as a function of the longitudinal position of the gap 115 (equivalently, the longitudinal position along the ingot 120). In some examples, sensor 202 may be operably coupled to a longitudinal actuator 130 through the computer system 299, and in some of those examples, a feedback configuration or servo mechanism may be employed to maintain the length parameter at or within a selected value. If the furnace 100 also includes a magnetic field source 300, in some examples, the source 300 and sensor 202 (and in some cases 201) may be used in conjunction to map the topography of the gap 115 in detail.Instead of or in addition to a set of sensors 202 that are longitudinally movable along the current-containing volume 10, in some examples, a set of magnetic field sensors 201 can be arranged at fixed positions along the current-containing volume 10 at a relatively high density of longitudinal spacing (e.g., as in the cases of FIGS. 1, 2, 3, and 5, the longitudinal spacing can be the same as the longitudinal spacing of the movable sensors 202). The corresponding magnetic field measurements from those highly spaced-apart sensors 201 can be used to estimate the longitudinal position of the gap 115 and to estimate the (one or more) length parameters of the one or more current segments 30.

[0016] As described in the incorporated references above, the systems, devices, and methods described above can advantageously be employed for process measurement and control and material characterization in a remelting furnace, e.g., a VAR furnace or an ESR furnace. Other novel and inventive methods for such process measurement and control and material characterization are disclosed below.

[0017] Solidification defects in the ingot 120 are known to be caused by, indicated by, and / or correlated with, transient conditions resulting from (i) spatial or temporal variations in heating or cooling of the molten pool 122 at the top of the ingot 120, (ii) spatial or temporal variations in the flow of current in the electrode 110, between the electrode 110 and the ingot 120, within the ingot 120, or between the ingot 120 and the crucible 101, or (iii) undesirable currents between the electrode 110 and the crucible 101 (e.g., side arcs). Variations that are cylindrically asymmetric and / or cannot be centered with respect to the crucible 101 and the ingot 120 solidifying in the crucible 101 can be particularly problematic. In a VAR furnace, most of the heat deposited in the molten pool 122 is due to the electric arc or discharge (i.e., current segment 30) between the electrode 110 and the ingot 120, and the molten metal dripping from the electrode 110 into the molten pool 122. The transverse distribution of molten metal dripping tends to reflect the transverse spatial distribution of (one or more) discharges (as further described below). In an ESR furnace, most of the heat deposited in the molten pool 122 is due to the resistant heating of the slag filling the gap 115, and the molten metal flowing from the electrode 110 into the molten pool 122 through the slag. As the molten pool 122 solidifies, most of the heat flowing out of the molten pool 122 flows radially outward into the crucible 101 near the top of the growing ingot 120, relying on contact between the ingot 120 and the crucible 101.

[0018] The non-concentric geometry of the electrode 110 within the crucible 101 may distort the distribution of the discharge 30 between the electrode 110 and the molten pool 122, and / or metal dropping, and / or (one or more) other localized current segments across the gap 115, or distort the distribution of heat accumulated in the ingot 120 through the molten pool 122. Such non-concentric geometry may include off-center positioning of the electrode 110 within the crucible 101, inclination of the electrode relative to the crucible 101, a bent or curved shape of the electrode 110, cracks, cavities, inclusions, or other structural irregularities within the electrode 110, or various combinations of some or all of these. As described above, the transverse size of the electrode 110 is necessarily smaller than the transverse size inside the crucible 101. If the lower end of electrode 110 (in the gap 115) is off-center relative to crucible 101 (and therefore to ingot 120), the distribution of electrical discharge and molten metal dripping across gap 115, or the heat flow into ingot 120, may also be off-center. One consequence may be asymmetrical erosion of the molten lower end of electrode 110, which leads to an undesirable convex, concave, or inclined lower surface of electrode 110. Another consequence may be non-uniform, heterogeneous, or asymmetrical solidification of ingot 120, which may lead to defects, inclusions, undesirable grain boundaries, or spatial variations in relative concentration of the alloy metal. It would be desirable to measure and estimate one or more of the following: (i) the transverse position of the electrode 110 and / or the lower end of the electrode 110 in the crucible 101; (ii) the cross-sectional position and shape of the electrode 110 as a function of the longitudinal position (along the electrode 110, along the gap 115 along the crucible 101, or both); or (iii) the transverse spatial distribution of the current 20 in the electrode 110 as a function of the longitudinal position (along the electrode 110, along the crucible 101, or both).It would be desirable to change, maintain, or control the estimated transverse position or angle of the electrode 110 in the crucible 101 to achieve or maintain relative concentricity of one or more of the following: (i) the current 20 flowing through volume 10, (ii) the transverse distribution of the position of current segment 30, or (iii) the transverse distribution of molten metal dropping from electrode 110 onto ingot 120.

[0019] The non-concentric current flows within and between the ingot 120 and the crucible 101 may exhibit irregularities during the remelting process, which can result in material defects or heterogeneity in the solidified ingot 120 (such as those described above). Generally, the molten pool 122 solidifies radially inward from the inner surface of the crucible 101. As the ingot 120 solidifies, it tends to shrink and move away from the crucible, and therefore, most of the current and heat flows between the ingot 120 and the crucible 101 are localized around the molten pool 122, near the top of the growing ingot 120. Detection of current flow between the ingot 120 and the crucible 101 at a location far in the longitudinal direction from the molten pool 122, particularly asymmetric current flow, can indicate excessively rapid or asymmetric cooling or solidification at that longitudinal location, which may, in some cases, indicate degraded material quality in the ingot 120 at that location. Detection of asymmetric current flow near the top of the growing ingot 120 can indicate an interruption in the desired gradual, orderly solidification of the molten pool 122. For example, a so-called shelf collapse or fall-in may occur, in which a portion of the partially solidified surface of the molten pool 122 breaks and falls back into the molten pool (similar to the calving of an iceberg from a glacier). That portion of the solidified ingot 120 will generally exhibit an increased possibility of defects (e.g., white spots) or variations in the alloy composition and will almost certainly exhibit a higher density of undesirable grain boundaries. Transient asymmetry in the flow of current into the crucible 101 at longitudinal positions of the molten pool 122 can indicate such shelf collapse events, and can indicate transverse or longitudinal positions along the solidified ingot 120 where corresponding degraded material quality can be found.

[0020] Accordingly, the apparatus of the present invention may include a first longitudinal electrical conductor 110 and a second longitudinal electrical conductor 120, a plurality of magnetic field sensors 201 and / or 202, and a computer system 299. The apparatus may be configured as a remelting furnace 100, an example of which is schematically shown in Figures 1 to 18B. The first longitudinal conductor may be an electrode 110, and the second longitudinal electrical conductor may be an ingot 120. The electrode 110 and the ingot 120 are end-to-end positioned inside the remelting furnace 100, within a current-containing volume 10. A primary current 20 flows mainly longitudinally as one or more localized current segments 30 (e.g., primary electrical discharge 30 in a VAR) spanning (i) at least portions of the electrode 110 and the ingot 120, and (ii) a gap 115 separating the electrode 110 and the ingot 120. One or more localized current segments 30 can move within the gap 115 in two transverse dimensions. Multiple magnetic field sensors 201 (fixed) and / or 202 (movable) are configured to measure magnetic field components in one or more spatial dimensions and are arranged at corresponding sensor positions configured around the lateral periphery of the current-containing volume 10. The sensors 201 / 202 are arranged at multiple different longitudinal positions along the furnace 100 and at multiple different circumferential positions around the furnace 100.

[0021] The computer system 299 receives corresponding signals from magnetic field sensors 201 and / or 202, indicating magnetic field components measured at a plurality of sensor locations, including sensor locations longitudinally offset from the arc gap 115. Based on at least two or more of the measured magnetic field components, the computer system 299 can calculate the estimated transverse position of one or more current segments 30 within the gap 115. In some examples, two or more magnetic field components measured at corresponding sensor locations longitudinally displaced from the gap 115 toward the electrode 110 (i.e., toward the top of the furnace 100) may be used by the computer system 299 to calculate the estimated relative tilt or transverse offset of the electrode 110 or a portion thereof, the estimated overall shape of the electrode 110, or the estimated spatial distribution of current flowing within the electrode 110, which may be affected by internal cracks, inclusions, or other electrode defects. In some examples, two or more magnetic field components measured at corresponding sensor positions displaced longitudinally from the gap 115 toward the ingot 120 (i.e., toward the bottom of the furnace 100) may be used by the computer system 299 to calculate an estimated spatial distribution of current in and / or between the ingot 120 and the crucible 101.

[0022] Figure 19 includes plots of simulated longitudinal magnetic field components as a function of longitudinal position along the furnace 100, calculated using different transverse positions of the right cylindrical electrode 110 in the crucible and different transverse positions of the current segment 30 in the arc gap 115. Curve 1 represents the case where both the electrode 110 and the current segment 30 are centered within the crucible 101, and as expected, the calculated magnitude of the longitudinal magnetic field is 0 across the entire furnace 100. Curves 2–4 represent transverse displacements of 10 mm, 25 mm, and 45 mm for both the electrode 110 and the current segment 30, respectively (i.e., the current segment 30 remains centered on the electrode 110 when the electrode 110 is displaced). Curves 5-8 represent transverse displacements of electrode 110 of 0 mm, 10 mm, 25 mm, and 45 mm, respectively, when the current segment is displaced a further 200 mm in the same direction (i.e., when electrode 110 is displaced, it is off-center relative to electrode 110). Curves 9-11 represent transverse displacements of electrode of 10 mm, 25 mm, and 45 mm, respectively, when the current segment 30 remains centered within crucible 101.

[0023] As can be seen from the plot in Figure 19, the longitudinal magnetic field magnitude near the gap 115 is considerably influenced by the position of the current segment 30. The current segments furthest from the center of the crucible (curves 5-8) exhibit a prominent peak in the region of gap 115. In contrast, at a position sufficiently displaced longitudinally from gap 115 (e.g., to the right of -1.5m in Figure 19), the longitudinal magnetic field magnitude depends almost entirely on the transverse offset of electrode 110. Curves representing the same displacement of electrode 110 but different displacements of current segment 30 converge to a common value. For a centered electrode, curves 1 and 5 converge to a longitudinal magnetic field magnitude of essentially 0 to the right of -1m in Figure 19. For electrode 110 displaced 10mm from the center, curves 2, 6, and 9 converge to approximately 0.5 Gauss to the right of -1.5m. For electrode 110 displaced 25 mm from the center, curves 3, 7, and 10 converge to approximately 1.2 Gauss to the right of -1.5 m. For electrode 110 displaced 45 mm from the center, curves 4, 8, and 11 converge to approximately 2.2 Gauss to the right of -1.5 m.

[0024] Figure 20 shows a plot of the magnetic field measured in the VAR reactor. It can be seen that the change in magnetic field strength between 4100 seconds and 4300 seconds resulted from the intentional movement of electrode 110 toward one side of crucible 101 and then back again.

[0025] The magnetic field components measured by some or all of the magnetic field sensors 201 and / or 202 may be recorded as a function of the moving longitudinal position of the gap 115 during the remelting process in the furnace 100. The longitudinal position of the gap 115 may be correlated with the corresponding longitudinal position along the solidified ingot 120 after the remelting process is complete, and thus can serve as an indicator of the relative material quality of different parts of the ingot 120. In some examples, the estimated transverse distribution of the position of current segments 30 (e.g., arcs or discharges) or molten metal drops (as described below) within the gap 115, calculated from the measured magnetic field components, may be recorded as a function of the longitudinal position along the solidified ingot 120 (as described herein and in some of the incorporated references). In some cases, the estimated presence or absence of current flowing between the electrode 110 and the crucible 101 (e.g., one or more side arcs) may be recorded as a function of the longitudinal position along the solidified ingot 120 (as described above and in some of the incorporated references), and the circumferential position of such side arcs may be recorded similarly. In some cases, the presence or absence of undesirable operating behavior or conditions (e.g., long arcs, constricted arcs, or glows) may be inferred or estimated from the measured magnetic field components and recorded as a function of the longitudinal position along the solidified ingot 120. In some cases, the transverse distribution of current flowing within the electrode 110 may be recorded as a function of the longitudinal position along the solidified ingot 120, and in some cases as a function of the longitudinal position within the crucible 101 or along the electrode 110. These recorded measurements can be used, for example, to correlate a given longitudinal position along the solidified ingot 120 with, for example, a corresponding transverse position at the end of the electrode 110, or the melting of a cracked, damaged, or otherwise irregular portion of the electrode 110.In some cases, the transverse or circumferential distribution of currents flowing in and / or between the ingot 120 and the crucible 101 is recorded as a function of the longitudinal position along the solidified ingot 120, and in some cases, as a function of the longitudinal position within the crucible 101. These recorded measurements may be used, for example, to correlate a given longitudinal position along the solidified ingot 120 with, for example, a corresponding shelf collapse event in the molten pool 122, or a portion of the ingot 120 that remained electrically in contact with the crucible after solidification.

[0026] In addition to recording the measured magnetic field components (and the estimators calculated therefrom), those measured magnetic field components or calculated quantities may be employed to induce or control active measures taken to maintain, modify, or control the remelting process. In some examples, the magnetic field source 300 may be employed to apply a magnetic field inside the remelting furnace 100, generally in or near the region of the gap 115, in order to maintain, modify, or control the transverse position of the current segment 30 within the gap 115 (as described above and in some of the incorporated references). The intensity and direction of those applied magnetic fields may be determined at least in part based on the measured magnetic field components or the quantities calculated therefrom, and in some of those examples, magnetic field sensors 201 and / or 202 may be coupled to the magnetic field source 300 by the computer system 299, either in a feedback configuration or as a servo mechanism. In some cases, the detection or estimation of the presence of one or more undesirable conditions within the furnace 100 (e.g., side arcs, long arcs, constructed arcs, or glows) may cause the computer system 299 to activate one or more magnetic field sources 300 to modify or terminate the undesirable conditions.

[0027] In some examples, the remelting furnace 100 may include corresponding additional sensors coupled to the furnace 100 or positioned on or within the furnace 100, which may include (i) the longitudinal or transverse position or velocity of the electrode 110, or one or more actuators 130 / 140 coupled to the electrode 110, (ii) the weight of the electrode 110, (iii) the magnitude or variation of the operating current, (iv) the difference between the operating current and the primary current 20, (v) the voltage drop or variation between the electrode 110 and the ingot 120, (vi) the electrical resistance or variation across the gap 115 (for example For example, through the slag filling the gap 115 (sometimes called a "swing" or "resistive swing"), (vii) the temperature inside the furnace 100, (viii) one or more temperature gradients inside or along the electrode 110, inside or along the ingot 120, or along or around the crucible 101, (ix) the pressure or composition of the gas or vapor inside the furnace 100, (x) the optical spectral characteristic light emitted by one or more current segments 30 / 32, or (xi) an image of the inside of the furnace 100. Signals generated by such additional sensors indicating the corresponding measured quantities are received by the computer system 299. In some cases, furnace operating parameters such as total current, internal vapor pressure (e.g., helium pressure between crucible 101 and the solidified portion of ingot 120, or argon backflow pressure), internal vapor composition, and slag depth or composition (in an ESR furnace) may be maintained, modified, or controlled by the computer system 299 in response to measured magnetic field components or quantities calculated therefrom. In some cases, the detection or estimation of the presence of undesirable operating conditions (e.g., those described above) may cause the computer system 299 to modify furnace operating parameters (e.g., those described above) to reduce or eliminate the undesirable conditions. For example, the detection of an undesirable glow or contraction arc may result in a change in the pressure, flow, or composition of the input gas.In some cases, measured magnetic field components or other furnace operating parameters (e.g., current, voltage, gas pressure or composition, excessive or insufficient movement of electrode 110) indicating furnace malfunction or improper setup or operation may cause the computer system 299 to alter or terminate the operation of furnace 100.

[0028] As described above, the remelting furnace 100 includes a longitudinal actuator 130 (explicitly shown only in Figures 15A to 18B, but included in any of the examples in Figures 1 to 18B) for controlling the vertical position of the electrode 110 in the crucible 101 to maintain a distance across the gap 115 within a desired range during the remelting process. The electrode 110 must move downward as it melts, because the ingot 120 grows more slowly than the electrode 110 shrinks during the remelting process. The longitudinal actuator 130 is connected to a computer system 299, which can control the vertical (i.e., longitudinal) movement of the electrode 110 based on one or more of the weight of the electrode 110, the melting duration, the voltage drop across the gap 115, or one or more measured magnetic field components (from which the distance across the gap 115 can be estimated, as described above and in some of the incorporated references).

[0029] In addition to the longitudinal actuator 130, in some examples the apparatus may include a transverse actuator 140 of any preferred type or configuration (e.g., hydraulic, gear-driven, servo-motor, etc.). The transverse actuator 140 is explicitly shown only in Figures 17A to 18B, but may be included in any of the examples in Figures 1 to 18B. In some examples the longitudinal actuator 130 and the transverse actuator 140 may be combined into a single dual-axis unit, while in other examples they may comprise separate units. The transverse actuator 140 may be configured to provide either or both (i) relative transverse movement of the electrode 110 in the crucible 101, or (ii) relative tilting of the electrode 110 in the crucible 101. The computer system 299 may generate one or more transverse position control signals to realize the transverse movement and / or tilting of the electrode 110 and transmit those signals to the transverse actuator 140. The transverse position control signal may be based at least partially on one or both of the estimated transverse position or estimated transverse distribution of (one or more) current segments 30, the estimated relative tilt or transverse offset of the electrode 110 in the crucible 101, or the estimated shape of the electrode 110. These estimated positions or shapes may be calculated based on measured magnetic field components measured by sensors 201 and / or 202, as described above. In some examples, the magnetic sensors 201 and / or 202 may be operably coupled to the transverse actuator 140, either in a feedback configuration or as a servo mechanism, using a computer system 299.

[0030] In some examples (for example, as in Figures 18A and 18B), the transverse actuator 140 may be used in combination with other features disclosed above, including, for example, one or more of the following: fixed and / or moving magnetic field sensors 201 / 202, a longitudinal actuator 130 coupled to a computer system 299 for changing, maintaining, or controlling the distance across the gap 115, or a magnetic field source 300 coupled to a computer system 299 for changing, maintaining, or controlling the transverse position or transverse distribution of (one or more) current segments 30 within the gap 115. In various examples, sensors 201 and / or 202 may be operably coupled to one, two, or all three of the longitudinal actuator 130, the magnetic field source 300, or the transverse actuator 140, or to other control devices of the furnace 100. For example, the magnetic field source 300 may be operated to align the center of the distribution of discharge locations within the gap 115, while the transverse actuator 140 is employed to align the center of the electrodes 110 within the crucible 101.

[0031] The dropping of molten metal from the melting electrode 110 into the molten pool 122 at the top of the ingot 120 has been described above. In addition to estimating the transverse position or distribution of transverse positions of one or more current segments 30 within the gap 115, it would also be desirable to estimate the distribution of the transverse positions of the drops onto the ingot 120.

[0032] Each molten drop can cause a so-called drip short when the dropping metal creates a transient conduction path between the electrode 110 and the ingot 120. The presence of this conduction path causes a transient spike or transient waveform in the voltage drop across the gap 115 or in the current 20 flowing through the furnace 100. In the inventive method, the magnetic field component can be measured at multiple longitudinal positions along the furnace 100 and / or multiple circumferential positions around the furnace 100. Estimates of the transverse position or distribution of transverse positions of one or more current segments 30 can be calculated as described above. However, if drip shorts are present, their transverse position estimates are inevitably affected by the presence of those drip shorts. A computer system 299 may be connected to monitor the voltage drop between the electrode 110 and the ingot 120 and the current flowing through the furnace 100. Detection of a rapid transient decrease in the voltage drop and a rapid transient increase in the current indicates the occurrence of a drip short. It should be noted that transients in furnace current and furnace voltage may last for only a few milliseconds. In some examples, the sampling rates of magnetic field sensors 201 and / or 202 may be fast enough (e.g., 500 Hz, 1 kHz, or even faster) to capture these transients. In other examples, lower sampling rates may be employed if the time constant in the detection system is long enough to detect transient features at lower sampling rates. Figure 21 shows some examples of measured current, voltage, and magnetic field components during the operation of a remelting furnace, where transient features in the voltage and current traces are clearly recognizable, as are the corresponding transient features in the magnetic field trace.

[0033] The computer system can use the magnetic field components measured during the time of the detected voltage and current transients to calculate the estimated transverse position of the current segment 30 (as described above). However, the estimated position thus calculated indicates the location of the drip short that caused those voltage and current transients, rather than the electrical discharge itself. During the remelting process, for each detected drip short, the corresponding estimated longitudinal position (the longitudinal position of the gap 115 during the time of the drip short) and the corresponding transverse position (calculated from the magnetic field components measured during the time of the drip short) can be recorded for the ingot 120. Two examples are shown in Figure 22.

[0034] While the transverse position of a drip short cannot be controlled, the average distribution of drip shorts can be modified, maintained, or controlled using the magnetic field source 300 described above. Drip shorts occur where melting occurs on the electrode 110, which is heated by one or more current segments (e.g., discharge 30). By using the magnetic field source 300 to modify, maintain, or control the position or distribution of (one or more) current segments 30 (as described above), the transverse spatial distribution of drip shorts can also be modified, maintained, or controlled (at least on average; the formation of drip shorts is a somewhat random process). A computer system 299 can monitor the occurrence and distribution of drip shorts and may cause the source 300 to apply a magnetic field to (indirectly) modify, maintain, or control the spatial distribution of drip shorts. In some examples, the magnetic field source 300 may be employed to move the (one or more) discharge 30, or the distribution of drip shorts, to diffuse the accumulation of heat into the molten pool 122 of the ingot 120. In some examples, the magnetic field source may be operated to move (one or more) discharge or drip-short distributions in, for example, a helical, circular, or star-shaped pattern to achieve the result. In some examples, diffusing the heat distribution can produce an ingot 120 with improved “skin quality,” i.e., a thinner layer of metal around the circumference of the solidified ingot 120, which would otherwise have to be removed later due to its poor quality.

[0035] An inventive method for measuring the location or distribution of a drip short may be used in combination with other features disclosed above, for example, one or more of the following: fixed and / or moving magnetic field sensors 201 / 202; a longitudinal actuator 130 coupled to a computer system 299 for changing, maintaining, or controlling the distance across the gap 115; a magnetic field source 300 coupled to a computer system 299 for changing, maintaining, or controlling the transverse position or transverse distribution of (one or more) current segments 30 within the gap 115; or a transverse actuator 140 coupled to a computer system for changing, maintaining, or controlling the transverse position of an electrode 110 within a crucible 101.

[0036] As described above, in some examples, the remelting furnace 100 may include additional sensors to measure or detect various properties of the furnace 100 or the remelting process occurring therein. The computer system 299 may receive signals indicating some or all of the magnetic field components measured using sensors 201 and / or 202, and / or signals indicating some or all of the quantities measured by additional sensors. In some examples, based at least partially on some or all of those received signals, or on quantities or parameters calculated, estimated, or derived therefrom (e.g., transverse or longitudinal position or distribution of current segment 30), the computer system 299 may be used to change, maintain, or control one or more operating parameters of the furnace 100 during the remelting process. In some examples, based at least partially on some or all of those received signals, or on quantities or parameters calculated, estimated, or derived therefrom, the computer system 299 may be used to generate and store a longitudinal or three-dimensional map of the ingot 120 produced by the remelting process.

[0037] In some cases, changing, maintaining, or controlling one or more operating parameters of the furnace 100 during the remelting process may include: (i) halting the remelting process; (ii) temporarily interrupting and then restarting the remelting process; (iii) rejecting or downgrading the ingot, or only selected portions of the ingot; or (iv) performing specific post-melt treatment on the ingot, or only specific portions of the ingot. (v) applying a magnetic field to change, maintain or control the transverse position or transverse distribution of one or more current segments within the gap 115; (vi) applying a magnetic field to change, maintain or control the transverse distribution of multiple drip shorts within the gap 115; (vii) applying a magnetic field to change, maintain or control the transverse distribution of heat accumulated on the surface of the ingot; (viii) applying a magnetic field to attenuate or terminate a side arc, contraction arc, glow, or long arc; (ix) changing, maintaining or controlling the distance between the electrode and the ingot across the gap 115; (x) crucible 101 This may include (xi) changing, maintaining, or controlling the angular or transverse position of the electrode 110 inside; (xii) changing, maintaining, or controlling the voltage across the gap 115; (xii) changing, maintaining, or controlling the current flowing through the electrode 110 and the ingot 120; (xiii) changing, maintaining, or controlling the electrical resistance across the gap 115 (for example, through the molten slag filling the gap 115; sometimes called the "swing" or "resistive swing"); (xiv) changing, maintaining, or controlling the immersion depth of the electrode 110 into the molten slag filling the gap 115; or (xv) changing, maintaining, or controlling the gas pressure or composition inside the furnace 100.

[0038] Measurements of the magnetic field components and / or other properties of the furnace 100 or the remelting process occurring therein may be recorded as a function of time during the remelting process, corresponding to the longitudinal position along the ingot 120. In some examples, one or more of the following may be recorded as a function of the longitudinal position along the ingot 120 formed by the remelting process in the remelting furnace 100. (i) transverse position or transverse distribution of one or more current segments, (ii) transverse position or transverse distribution of multiple drip shorts, (iii) angle or transverse position of the electrode in the crucible, (iv) distance across the gap 115 between the electrode 110 and the ingot 120, (v) surface profile of the electrode 110 obtained by estimating the distance across the gap 115 as a function of the transverse position of the current segment 30, (vi) presence or duration or location of one or more side arcs 32, (vii) presence or duration or location of one or more contraction arcs, glows, or long arcs, (viii) detection of the presence or location of cracks or defects in the electrode during the corresponding time portion of the remelting process that resulted in the ingot, (ix) longitudinal shape of the electrode, (x) gas pressure or composition in the furnace, (xi) slag depth or composition in the furnace, (xii) occurrence or location of shelf collapse events into the molten pool, or (xiii) transient fluctuations of current or voltage across the gap 115.

[0039] One or more of these measured quantities may be used to generate and store a map of ingot 120, which shows the remelting conditions, metal quality, or specified or recommended post-molten treatment as a function of longitudinal or three-dimensional position within ingot 120. For example, metal quality as a function of position in ingot 120 may be classified based on the suitability of the metal for subsequent applications, e.g., jet turbine blades or nuclear power plants versus golf clubs. It should be noted that higher quality and lower quality metals may be obtained from the same ingot 120 and directed to different end uses, which reduces the need for waste or further remelting. In another example, the metal of ingot 120 may be classified (as a function of position) based on its suitability for different post-molten treatment steps (e.g., machining versus extrusion versus hot forging or cold forging).

[0040] In some examples, conventional computer algorithms may be executed by a computer system 299 to control the remelting process and / or map the resulting ingot 120. In some examples, quantities measured by magnetic field sensors 201 or 202, or by other additional sensors, may be used as direct inputs to the process control algorithm or recorded as part of the ingot map. In some examples, quantities estimated, calculated, or derived from measured quantities, such as the spatial distribution of drip shorts estimated from magnetic field and voltage measurements, or the side-arc position estimated from magnetic field measurements and the difference between the input current and the primary current, may be employed.

[0041] In some examples, the computer system 299 may include an artificial intelligence subsystem (AI), a machine learning subsystem (ML), or a neural network (NN). In such examples, the AI, ML, or NN may be provided with training data including (i) signals received from magnetic field sensors 201 and / or 202 and additional sensors during multiple remelting processes, and (ii) observed or measured metal quality as a function of the three-dimensional position within the corresponding ingot 120 produced by those multiple remelting processes. In some examples, the training data may include the magnetic field component applied by source 300. In some examples, signals from various sensors may serve as training data, and in other examples, quantities estimated, calculated, or derived from sensor signals (e.g., estimated position or estimated distribution of current segment 30) may be included in the training data. Once the AI, ML, or NN is properly trained, in some examples it may be used to modify, maintain, or control one or more operating parameters of the furnace 100 during subsequent remelting processes in response to signals received from various sensors during those processes. In some examples, a trained AI, ML, or NN may be employed to map the ingot 120 based on signals received from various sensors during the remelting process that yielded the ingot 120. In some examples, the AI, ML, or NN may be employed for both purposes. In some examples, the AI, ML, or NN may employ a so-called explainable algorithm, and thus the behavior of the computer system 299 during the remelting process, or the mapping of the ingot 120, may be analyzed and understood; in other examples, such analysis may not be possible to extract from the AI, ML, or NN. In some examples, the AI, ML, or NN system may be trained to recognize anomalies occurring during the remelting process while the furnace 100 is operating and to pinpoint their location (in the longitudinal direction or in three dimensions).Anomaly detection can be implemented in any preferred manner, including, for example, observing changes in the mean or standard deviation (or (one or more) other statistical parameters) of one or more measured or estimated / calculated / derived quantities, or the time frequency of such changes.

[0042] Several specific examples may be illustrative. In the first specific example, magnetic field measurements (e.g., the vertical component near the gap 115), furnace gas composition (e.g., copper detected by mass spectrometry), or spectral characteristics of light produced within the furnace 100 (e.g., atomic copper emission) may indicate side arcs at a given longitudinal and circumferential position of the ingot 120. The computer system 299 may modify the magnetic field applied by source 300, temporarily reducing the voltage across the gap 115 until the signs of side arc 32 subside or disappear, and then return the furnace 100 to its previous operating conditions. Alternatively or in addition, a map of the ingot 120 may indicate that a volume of metal around the estimated location of the side arc 32 should be discarded. In a second specific example, magnetic field measurements (both near the gap 115 and displaced longitudinally from the gap 115) and voltage measurements can show a distorted drip short distribution toward the edge of the ingot 120 and the corresponding transverse displacement of the electrode 110 (these may also be shown by images collected within the furnace 100). The computer system 299 may, if necessary, change the transverse position or tilt of the electrode 110 to realign the center of the drip short distribution with or without applying a magnetic field using one or more of the sources 300. Alternatively or in addition, a map of the ingot 120 may show that the volume of metal around the observed distorted distribution of drip shorts is downgraded for use in non-critical applications only. In a third specific example, asymmetric heating of crucible 101 near gap 115, asymmetric current flow into crucible 101 near gap 115, or images collected within furnace 100 may indicate a so-called shelf collapse event. A map of ingot 120 may show that a volume of metal around the estimated location of the shelf collapse should be discarded. Numerous other examples may be implemented within the scope of this disclosure or the appended claims.

[0043] The remelting process control and ingot mapping enabled by the disclosed apparatus and methods offer several advantages, including, but not limited to, improved safety, higher overall material quality, and reduced waste from substandard ingot materials.

[0044] The systems and methods disclosed herein may be implemented as general-purpose or dedicated computers or servers, or as other programmable hardware devices programmed through software, or as hardware or equipment “programmed” by them or through hardwiring, or as a combination of the two. A “computer” or “server” may comprise a single machine or multiple interacting machines (located in a single location or in multiple remote locations). Computer programs or other software code may be implemented, if used, on tangible, non-temporary, transient or persistent storage media or interchangeable media, such as by including the programming in microcode, machine code, network-based or web-based or distributed software modules working together, RAM, ROM, CD-ROM, CD-R, CD-R / W, DVD-ROM, DVD±R, DVD±R / W, hard drives, thumb drives, flash memory, optical media, magnetic media, semiconductor media, or any future computer-readable storage substitutes. Electronic representations of datasets may be read from, received from, or stored in any of the tangible, non-temporary computer-readable media referred to herein.

[0045] In addition to the foregoing, the following exemplary embodiments fall within the scope of this disclosure or the appended claims. Any given example below that references multiple prior examples is understood to refer only to prior examples that are not contradictory to the given example, and implicitly exclude prior examples that are contradictory to the given example.

[0046] Example 1. (a) A first longitudinal electrical conductor and a second longitudinal electrical conductor positioned end-to-end within a current-containing volume through which a primary current flows (i) through at least portions of the first and second conductors and (ii) across a gap separating the first and second conductors, with the one or more current segments being movable in two transverse dimensions within the gap, and the first and second longitudinal electrical conductors, as one or more transverse localized current segments, flowing mainly in the longitudinal direction, and (b) (i) configured to measure magnetic field components or magnetic field magnitudes in one or more spatial dimensions, and (ii) a plurality of different longitudinal positions and a plurality of different circumferential positions An apparatus comprising (c) a plurality of magnetic field sensors arranged at corresponding sensor positions configured around the lateral periphery of a current-containing volume, and a computer system comprising one or more electronic processors and one or more digital storage media coupled thereto, wherein the computer system is structured, connected, and programmed to (i) receive corresponding signals from the magnetic field sensors indicating magnetic field components measured at a plurality of corresponding sensor positions offset longitudinally from the gap, and (ii) calculate an estimated transverse spatial distribution of current in or through one or both of the first and second conductors based on at least a portion of two or more of the measured magnetic field components.

[0047] Example 2. The apparatus according to Example 1, wherein at least one of the current segments is an electrical discharge or arc formed across the gap between the first conductor and the second conductor.

[0048] Example 3. The apparatus according to Example 1, wherein the current-containing volume is the internal volume of the remelting furnace, the first conductor is the electrode of the remelting furnace, and the second conductor is the ingot formed by the remelting process in the crucible of the remelting furnace.

[0049] Example 4. The apparatus according to Example 3, wherein at least one of the one or more current segments is an electrical discharge or arc formed across the gap between the electrode and the ingot.

[0050] Example 5. The apparatus according to Example 3 or 4, wherein at least one of the current segments is a transient short circuit through a droplet of molten metal dripping across the gap between the electrode and the ingot.

[0051] Example 6. The apparatus according to any one of Examples 3 to 5, wherein a layer of molten slag at least partially fills the gap between the electrode and the ingot, and one or more current segments pass through the slag layer.

[0052] Example 7. The apparatus according to any one of Examples 3 to 6, wherein the computer system is structured, connected, and programmed to calculate the longitudinal or transverse position of shelf collapse events of the solidifying portion of the molten pool on the upper surface of the ingot, based at least partially on two or more of the measured magnetic field components.

[0053] Example 8. The apparatus according to any one of Examples 1 to 7, further structured, connected, and programmed to (i) receive corresponding signals from a magnetic field sensor indicating magnetic field components measured at a plurality of corresponding sensor locations, and (ii) calculate an estimated transverse position or estimated transverse distribution of one or more current segments in a gap based on at least a portion of two or more of the measured magnetic field components.

[0054] Example 9. The apparatus according to any one of Examples 1 to 8, further comprising a transverse actuator configured to provide transverse or angular movement of a first conductor or a second conductor relative to each other, wherein a computer system is further structured, connected, and programmed to (i) generate one or more transverse position control signals based at least in part on one or both of an estimated transverse position or estimated transverse distribution of one or more primary electrical discharges, or an estimated relative transverse offset between the first conductor and the second conductor, and (ii) transmit one or more transverse position control signals to the transverse actuator to change, maintain, or control the relative transverse position or angle between the first conductor and the second conductor.

[0055] Example 10. The apparatus according to any one of Examples 1 to 9, further comprising a longitudinal actuator configured to provide longitudinal movement of a first conductor or a second conductor relative to each other, wherein a computer system is further structured, connected, and programmed to (i) calculate an estimated gap distance between the first conductor and the second conductor based at least in part on two or more of the measured magnetic field components; (ii) generate one or more longitudinal position control signals based at least in part on the estimated gap distance; and (ii) transmit one or more longitudinal position control signals to the longitudinal actuator to change, maintain, or control the estimated gap distance between the first conductor or the second conductor.

[0056] Example 11. The apparatus according to any one of Examples 1 to 10, further comprising one or more magnetic field sources positioned at corresponding source locations configured around the lateral periphery of a current-containing volume and configured to apply corresponding applied magnetic fields having corresponding non-zero components oriented transversely across at least a portion of the current-containing volume including a gap, wherein a computer system is further structured, connected, and programmed to (i) generate one or more applied magnetic field control signals based at least partially on one or both of the estimated transverse positions or estimated transverse distributions of one or more current segments in the gap, and (ii) transmit one or more applied magnetic field control signals to the magnetic field sources to change, maintain, or control the position or distribution of one or more current segments in the gap.

[0057] Example 12. The apparatus according to any one of Examples 1 to 11, wherein the computer system is structured, connected, and programmed to calculate, based at least partially on two or more of the measured magnetic field components, (i) an estimated relative transverse offset or relative angle between a first conductor and a second conductor, (ii) a longitudinal shape profile of one or both of the first or second conductors, or (iii) the corresponding location, size, or shape of one or more cracks, inclusions, cavities, or structural defects within one or both of the first or second conductors.

[0058] Example 13. The apparatus according to any one of Examples 3 to 12, wherein the computer system is structured, connected, and programmed to (i) receive corresponding signals from magnetic field sensors indicating magnetic field components measured at a plurality of corresponding sensor locations; (ii) receive signals indicating the magnitude of the primary current and the furnace voltage across the electrode and the ingot; (iii) detect a drip short between the electrode and the ingot based on a measured transient deviation of the primary current or furnace voltage indicating a drip short; and (iv) calculate an estimated transverse position of the detected drip short in the gap based on at least a portion of two or more of the magnetic field components measured at the time of the detected drip short.

[0059] Example 14. (a) A longitudinal first conductor configured as an electrode and a longitudinal second conductor configured as an ingot, positioned end-to-end within a current-containing volume in an arc furnace, through which a primary current flows, (i) through at least portions of the electrode and the ingot, and (ii) across a gap separating the electrode and the ingot, with one or more primary discharges flowing mainly longitudinally as one or more primary discharges movable in two transverse dimensions within the gap, and (b) a plurality of sensors configured to measure magnetic field components in two or more spatial dimensions, and (ii) arranged at corresponding sensor positions configured around the lateral periphery of the arc furnace at a plurality of different longitudinal positions and a plurality of different circumferential positions. An apparatus comprising (c) a magnetic field sensor and a computer system comprising one or more electronic processors and one or more digital storage media coupled thereto, wherein the computer system is structured, connected, and programmed to (i) receive corresponding signals from the magnetic field sensor indicating magnetic field components measured at a plurality of corresponding sensor locations; (ii) receive signals indicating the magnitude of the primary current and the furnace voltage across the electrode and the ingot; (iii) detect a drip short between the electrode and the ingot based on a measured transient deviation of the primary current or furnace voltage indicating a drip short; and (iv) calculate an estimated transverse position of the detected drip short in the gap based on at least a portion of two or more of the magnetic field components measured at the time of the detected drip short.

[0060] Example 15. The apparatus according to Example 13 or 14, further structured, connected, and programmed to calculate the estimated transverse locations for multiple detected drip shorts and the transverse spatial distribution of those multiple estimated drip short locations.

[0061] Example 16. The apparatus according to any one of Examples 13 to 15, further structured, connected, and programmed to (i) receive corresponding signals from magnetic field sensors indicating magnetic field components measured at a plurality of corresponding sensor locations, and (ii) calculate an estimated transverse position or estimated transverse distribution of one or more primary electrical discharges in a gap based on at least a portion of two or more of the measured magnetic field components.

[0062] Example 17. The apparatus according to any one of Examples 13 to 16, further comprising one or more magnetic field sources positioned at corresponding source positions configured around the lateral periphery of an arc furnace and configured to apply corresponding applied magnetic fields having corresponding non-zero components oriented transversely over at least a portion of the arc furnace, including gaps, wherein a computer system is further structured, connected, and programmed to (i) generate one or more applied magnetic field control signals based at least partially on the estimated distribution of drip shorts, or the estimated transverse position or estimated transverse distribution of one or more primary electrical discharges, and (ii) transmit one or more applied magnetic field control signals to the magnetic field sources to change, maintain, or control the position or distribution of one or more primary discharges, thereby changing, maintaining, or controlling the distribution of drip shorts.

[0063] Example 18. The apparatus according to any one of Examples 1 to 17, further comprising one or more magnetic field sources positioned at corresponding source locations configured around the lateral periphery of a current-containing volume and configured to apply corresponding applied magnetic fields having corresponding non-zero components oriented transversely across at least a portion of the current-containing volume including a gap, wherein a computer system is further structured, connected, and programmed to (i) generate one or more applied magnetic field control signals based at least partially on one or both of the estimated transverse positions or estimated transverse distributions of one or more current segments, and (ii) transmit one or more applied magnetic field control signals to the magnetic field sources to change, maintain, or control the transverse positions or transverse distributions of one or more current segments within the gap.

[0064] Example 19. The apparatus according to Example 17 or 18, wherein one or more magnetic field sources include one or more fixed sources.

[0065] Example 20. The apparatus according to any one of Examples 17 to 19, wherein one or more magnetic field sources include one or more sources that are movable longitudinally along a current-containing volume.

[0066] Example 21. The apparatus according to any one of Examples 1 to 20, wherein the multiple magnetic field sensors include one or more fixed sensors.

[0067] Example 22. The apparatus according to any one of Examples 1 to 21, wherein the multiple magnetic field sensors include one or more sensors that are movable longitudinally along a current-containing volume.

[0068] Example 23. The apparatus according to any one of Examples 1 to 22, wherein calculations based on the magnetic field components measured by the sensors include corrections for one or more of the following: (i) magnetic fields caused by external conductors carrying current to or from the first and second conductors, (ii) geomagnetic fields, (iii) other external magnetic fields, or (iv) mismatches of one or more sensors.

[0069] Example 24. The apparatus according to any one of Examples 3 to 23, further comprising corresponding additional sensors coupled to or positioned on or inside the furnace, wherein the corresponding additional sensors are configured to measure one or more or all of the following: (i) longitudinal or transverse position or velocity of an electrode, or one or more actuators coupled to an electrode; (ii) weight of an electrode; (iii) magnitude or variation of the operating current; (iv) difference between the operating current and the primary current; (v) voltage drop or variation between the electrode and the ingot; (vi) electrical resistance or variation across the gap; (vii) temperature inside the furnace; (viii) one or more temperature gradients in or along the electrode, in or along the ingot, or along or around the crucible; (ix) pressure or composition of gas or vapor inside the furnace; (x) optical spectral characteristic light emitted by one or more current segments; or (xi) an image of the inside of the furnace.

[0070] Example 25. A method employing the apparatus described in any one of Examples 3 to 24, wherein the method comprises: (i) transverse position or transverse distribution of one or more current segments, (ii) transverse position or transverse distribution of multiple drip shorts, (iii) angle or transverse position of an electrode in a crucible, (iv) distance across the gap between the electrode and the ingot, (v) surface profile of the electrode obtained by estimating the distance across the gap as a function of the transverse position of the current segments, (vi) presence or duration or location of one or more side arcs, (vii) one A method comprising recording one or more of the following: (viii) the presence, duration, or location of multiple contracting arcs, glows, or long arcs; (ix) the presence or location of cracks or defects in the electrode during the corresponding time portion of the remelting process that resulted in the ingot; (x) the longitudinal shape of the electrode; (x) the gas pressure or composition in the furnace; (xi) the slag depth or composition in the furnace; (xii) the occurrence or location of a shelf collapse event into the molten pool; (xiii) transient fluctuations of current, voltage, or electrical resistance across the gap; (xiv) the immersion depth of the electrode into the molten slag filling the gap; (xv) the measured magnetic field component; or (xvi) the applied magnetic field component.

[0071] Example 26. A method employing the apparatus described in any one of Examples 3 to 24, wherein the method, in response to one or more magnetic field components measured by one or more corresponding sensors during the remelting process, or one or more estimates calculated therefrom, (i) terminate the remelting process; (ii) temporarily suspend and then resume the remelting process; (iii) reject or downgrade an ingot; (iv) reject or downgrade only selected portions of an ingot; (v) apply a magnetic field to change, maintain or control the transverse position or transverse distribution of one or more current segments in a gap; (vi) apply a magnetic field to change, maintain or control the transverse distribution of multiple drip shorts in a gap; (vii) change the transverse distribution of heat accumulated on the surface of the ingot. A method comprising: (viii) applying a magnetic field to maintain or control; (ix) applying a magnetic field to attenuate or terminate a side arc, contraction arc, glow, or long arc; (x) changing, maintaining, or controlling the distance between the electrode and the ingot across the gap; (x) changing, maintaining, or controlling the angular or transverse position of the electrode in the crucible; (xi) changing, maintaining, or controlling the voltage across the gap; (xii) changing, maintaining, or controlling the electrical resistance across the gap; (xiii) changing, maintaining, or controlling the current flowing through the electrode and the ingot; (xiv) changing, maintaining, or controlling the immersion depth of the electrode in the molten slag filling the gap; or (xv) changing, maintaining, or controlling the gas pressure or composition in the furnace.

[0072] Example 27. A method employing the apparatus described in Example 24, the method comprising: (a) supplying an operating current to a furnace during a remelting process using a remelting furnace, such that at least a portion of the operating current flows through the furnace as a primary current; (b) using a plurality of magnetic field sensors to measure, as a function of time during the remelting process, the magnetic field component or magnitude in one or more spatial dimensions at some or all of the corresponding sensor locations; (c) using corresponding additional sensors to measure, as a function of time during the remelting process, (i) the longitudinal or transverse position or velocity of an electrode, or one or more actuators coupled to an electrode; (ii) the weight of the electrode; (iii) the magnitude or variation of the operating current; (iv) the difference between the operating current and the primary current; (v) the voltage drop or variation between the electrode and the ingot; (vi) the electrical resistance across the gap or variation thereof; (vii) the temperature inside the furnace; (viii) one or more temperature gradients in or along the electrode, in or along the ingot, or along or around the crucible; (ix) the gas or vapor inside the furnace. A method comprising measuring one or more or all of the following: (x) pressure or composition, (x) optical spectral characteristic light emitted by one or more current segments, (xi) immersion depth of the electrodes in the molten slag filling the gap or its variation, or (xii) an image of the inside of the furnace; and (d) using a computer system to (i) receive a signal indicating some or all of the magnetic field components measured in part (b), (ii) receive a signal indicating some or all of the quantities measured in part (c), and (iii) change, maintain or control one or more operating parameters of the furnace during the remelting process based at least in part on the received signals in part (b) or (c), or quantities or parameters calculated, estimated or derived therefrom, or (iv) generate and store a longitudinal map or three-dimensional map of the ingot produced by the remelting process based at least in part on the received signals in part (b) or (c), or quantities or parameters calculated, estimated or derived therefrom.

[0073] Example 28. (a) During a remelting process using a remelting furnace, supplying an operating current to the furnace, wherein at least a portion of the operating current flows generally as a primary current in the longitudinal direction as one or more transverse localized current segments spanning (i) at least a portion of metal electrodes positioned in the crucible of the remelting furnace, (ii) at least a portion of the metal ingot formed in the crucible by the melting of the electrodes during the remelting process, and (iii) a gap separating the electrodes and the ingot, wherein one or more current segments are movable in two transverse dimensions within the gap, and as one or more transverse localized current segments, the current flows generally as a primary current in the longitudinal direction; (b) Measuring, as a function of time during the remelting process, magnetic field components or magnetic field magnitudes in one or more spatial dimensions at some or all of the corresponding sensor positions using a plurality of magnetic field sensors positioned at corresponding fixed or movable sensor positions configured around the lateral periphery of the crucible at a plurality of different longitudinal positions and a plurality of different circumferential positions; (c) coupled to the furnace, or on or inside the furnace. Using corresponding sensors positioned at the same location, the system measures, as a function of time during the remelting process, one or more or all of the following: (i) longitudinal or transverse position or velocity of the electrode, or one or more actuators coupled to the electrode; (ii) weight of the electrode; (iii) magnitude or variation of the operating current; (iv) difference between the operating current and the primary current; (v) voltage drop or variation between the electrode and the ingot; (vi) electrical resistance across the gap or variation thereof; (vii) temperature inside the furnace; (viii) one or more temperature gradients in or along the electrode, in or along the ingot, or along or around the crucible; (ix) pressure or composition of the gas or vapor inside the furnace; (x) optical spectral characteristic light emitted by one or more current segments; (xi) immersion depth of the electrode into the molten slag filling the gap or variation thereof; or (xii) images of the inside of the furnace; and (d) comprising one or more electronic processors and one or more digital storage media coupled thereto, structured, connected, and programmed for that purpose.A method comprising using a computer system to (i) receive a signal indicating some or all of the magnetic field components measured in part (b), (ii) receive a signal indicating some or all of the quantities measured in part (c), and (iii) change, maintain, or control one or more operating parameters of the furnace during the remelting process based at least partially on the received signals or quantities or parameters calculated, estimated, or derived therefrom, or (iv) generate and store a longitudinal map or three-dimensional map of the ingot produced by the remelting process based at least partially on the received signals or quantities or parameters calculated, estimated, or derived therefrom.

[0074] Example 29. Based at least in part on the received signal, or quantities or parameters calculated, estimated, or derived therefrom, during the remelting process: (i) abort the remelting process; (ii) temporarily suspend and then resume the remelting process; (iii) reject or downgrade the ingot, or only selected portions of the ingot; (iv) specify or recommend specific post-melting treatments for the ingot, or only specific portions of the ingot; (v) apply a magnetic field to change, maintain, or control the transverse position or transverse distribution of one or more current segments in the gap; (vi) apply a magnetic field to change, maintain, or control the transverse distribution of multiple drip shorts in the gap; (vii) change or maintain the transverse distribution of heat accumulated on the surface of the ingot. The method according to Example 27 or 28, including (viii) applying a magnetic field to attenuate or control a side arc, contraction arc, glow, or long arc; (ix) changing, maintaining, or controlling the distance between the electrode and the ingot across the gap, or the depth of immersion of the electrode into the molten slag filling the gap; (x) changing, maintaining, or controlling the angular or transverse position of the electrode in the crucible; (xi) changing, maintaining, or controlling the voltage across the gap; (xii) changing, maintaining, or controlling the electrical resistance across the gap; (xiii) changing, maintaining, or controlling the current flowing through the electrode and the ingot; or (xiv) changing, maintaining, or controlling the gas pressure or composition in the furnace.

[0075] Example 30. The method provides, as a function of the longitudinal position along the ingot formed by the remelting process in the remelting furnace, (i) the transverse position or transverse distribution of one or more current segments, (ii) the transverse position or transverse distribution of multiple drip shorts, (iii) the angle or transverse position of the electrode in the crucible, (iv) the distance across the gap between the electrode and the ingot, (v) the electrode surface profile obtained by estimating the distance across the gap as a function of the transverse position of the current segments, (vi) the presence or duration or position of one or more side arcs, (vii) the presence or absence of one or more contraction arcs, glows, or long arcs. The method according to any one of Examples 27 to 29, comprising recording one or more of the following: (viii) duration or location, (viii) detection of the presence or location of cracks or defects in the electrode during the corresponding time portion of the remelting process that resulted in the ingot, (ix) longitudinal shape of the electrode, (x) gas pressure or composition in the furnace, (xi) slag depth or composition in the furnace, (xii) occurrence or location of a shelf collapse event into the molten pool, (xiii) transient fluctuations of current or voltage or electrical resistance across the gap, (xiv) one or more magnetic field components, (xv) one or more applied magnetic field components, or (xvi) immersion depth of the electrode into the molten slag filling the gap.

[0076] Example 31. The method of Example 30, wherein the map shows remelting conditions, metal quality, or specified or recommended post-molten treatment as a function of longitudinal or three-dimensional positions within the ingot.

[0077] Example 32. The method according to any one of Examples 25 to 31, wherein the computer system includes an artificial intelligence subsystem, a machine learning subsystem, or a neural network, and the method further comprises (A) providing the artificial intelligence subsystem, a machine learning subsystem, or a neural network with (i) received signals from parts (b) and (c) for a plurality of remelting processes and (ii) observed or measured metal quality as a function of the three-dimensional position in the corresponding ingot brought about by the plurality of remelting processes as training data; (B) providing the artificial intelligence subsystem, a machine learning subsystem, or a neural network with received signals from parts (b) and (c) during subsequent remelting processes; and (C) using the artificial intelligence subsystem, a machine learning subsystem, or a neural network to change, maintain, or control one or more operating parameters of the furnace during subsequent remelting processes.

[0078] Example 33. The method according to any one of Examples 25 to 31, wherein the computer system includes an artificial intelligence subsystem, a machine learning subsystem, or a neural network, and the method further comprises (A) providing the artificial intelligence subsystem, a machine learning subsystem, or a neural network with (i) received signals from parts (b) and (c) for a plurality of remelting processes, and (ii) observed or measured metal quality as a function of the three-dimensional position in the corresponding ingots resulting from the plurality of remelting processes, as training data; (B) providing the artificial intelligence subsystem, a machine learning subsystem, or a neural network with received signals from parts (b) and (c) during subsequent remelting processes; and (C) using the artificial intelligence subsystem, a machine learning subsystem, or a neural network to generate and store a map of the ingots resulting from the subsequent remelting processes, wherein the map indicates remelting conditions, metal quality, or specified or recommended post-melting treatment as a function of the longitudinal position or three-dimensional position in the ingots.

[0079] This disclosure is illustrative and not limiting. Further modifications will be obvious to those skilled in the art in light of this disclosure and will fall within the scope of this disclosure or the appended claims. Equivalents of the exemplary embodiments and methods disclosed, or modifications thereof, will fall within the scope of this disclosure or the appended claims.

[0080] In the modes for carrying out the invention described above, various features may be grouped together into several exemplary embodiments in order to streamline the disclosure. This method of disclosure should not be interpreted as indicating an intention that the claimed embodiments require more features than are explicitly stated in the corresponding claims. Rather, as represented by the appended claims, the subject matter of the invention may consist of fewer features than all the features of a single disclosed exemplary embodiment. Accordingly, this disclosure should be interpreted as implicitly disclosing any embodiments having any preferred subset of one or more features shown, described or claimed in this application, including subsets that may not be expressly disclosed herein. A “preferred” subset of features includes only features that are neither incompatible nor mutually exclusive with respect to other features of that subset. Accordingly, the appended claims as a whole are incorporated into the modes for carrying out the invention as described herein, and each claim stands independently as a separately disclosed embodiment. In addition, each of the attached dependent claims shall be written in multiple dependent forms solely for the purpose of disclosing the claims by incorporating them into modes for carrying out the invention, and shall be construed as dependent on all prior claims that are not inconsistent with the dependent claim. Furthermore, it should be noted that the cumulative scope of the attached claims may, though not necessarily, encompass the entire subject matter disclosed in this application.

[0081] The following interpretations shall apply to the purposes of this disclosure and the attached claims. The words “comprising,” “including,” “having,” and their variations shall be interpreted as open-ended terms, wherever they appear, having the same meaning as if a phrase such as “at least” were added after each instance thereof, unless otherwise specified. The article “a” shall be interpreted as “one or more,” unless the limitation “only one of the,” “a single one of the,” or other similar limitation is explicitly stated or implicit in a particular context. Similarly, the article “the” shall be interpreted as “one or more of the,” unless the limitation “only one of the,” “a single one of the,” or other similar limitation is explicitly stated or implicit in a particular context. The conjunction "or" should be interpreted inclusively unless (i) otherwise explicitly stated, for example, by the use of "either...or," "only one of," or similar phrasing, or (ii) unless it is implicitly or explicitly understood or disclosed that two or more of the listed alternatives should be incompatible or mutually exclusive within a particular context. In the latter case, "or" would be understood to encompass only those combinations with non-mutually exclusive alternatives. For example, "dog or cat," "one or more dogs or cats," and "one or more dogs or cats" would each be interpreted as one or more dogs without cats, or one or more cats without dogs, or one or more of each.

[0082] Wherever numerical quantities are expressed for the purposes of this disclosure or the attached claims (with or without terms such as “about,” “about equal to,” “substantially equal to,” “about greater than,” “about less than,” etc.), unless a different interpretation is expressly stated, or where a different interpretation is implicit or inherent (e.g., any small integer quantity), standard conventions regarding measurement accuracy, rounding errors, and significant figures shall apply. With respect to null quantities described by phrases such as “equal to zero,” “absent,” “erased,” “negligible,” or “hindrance” (with or without terms such as “about,” “substantially”), each such phrase shall indicate, for practical purposes in the context of the intended operation or use of the disclosed or claimed apparatus or method, that the overall behavior or performance of the apparatus or method is no different from what would have occurred if the null quantity had been substantially completely removed, exactly equal to zero, or otherwise exactly nulled. Terms such as “parallel,” “perpendicular,” “orthogonal,” “coplanar,” and “aligned” (with or without terms such as “approximately” or “substantially”) shall be interpreted similarly.

[0083] For the purposes of this disclosure and the accompanying claims, any labeling of embodiments, examples, or elements, steps, limitations, or other parts of a claim (e.g., first, second, third, etc., (a), (b), (c), etc., or (i), (ii), (iii), etc.) is for clarity only and shall not be construed as implying any ordering or priority of the such labeled parts. Where any such ordering or priority is intended, it will be expressly represented in the embodiments, examples, or claims, or, in some cases, it will be implicit or inherent based on the specific content of the embodiments, examples, or claims.

[0084] If it is desired that the provisions of Section 112(f) of the U.S. Patent Act be enforced in an apparatus claim within the attached claims, the word “means” shall appear in that apparatus claim. If it is desired that those provisions be enforced in a method claim, the word “step for” shall appear in that method claim. Conversely, if the words “means” or “step for” do not appear in a claim, the provisions of Section 112(f) of the U.S. Patent Act shall not be enforced for that claim.

[0085] If any one or more disclosures are incorporated herein by reference, and such incorporated disclosures conflict with or differ in scope from this disclosure, in part or in whole, this disclosure shall prevail to the extent of the conflict, the broader disclosure, or the broader definition of the terms. If such incorporated disclosures conflict with each other in part or in whole, the more recent disclosure shall prevail to the extent of the conflict.

[0086] Abstracts are provided as needed to assist those exploring specific subject matter within the patent documents. However, abstracts do not imply that any elements, features, or limitations presented herein are necessarily encompassed by any particular claim. The scope of subject matter covered by each claim shall be determined solely by the presentation of that claim.

Claims

1. (a) A longitudinal first conductor configured as an electrode and a longitudinal second conductor configured as an ingot, positioned end-to-end within a current-containing volume in an arc furnace, through which a primary current flows, (i) through at least portions of the electrode and the ingot, and (ii) across a gap separating the electrode and the ingot, wherein the one or more primary discharges flow mainly longitudinally as one or more primary discharges movable in two transverse dimensions within the gap, the longitudinal first conductor configured as an electrode and the longitudinal second conductor configured as an ingot, (b) (i) configured to measure magnetic field components in two or more spatial dimensions, and (ii) arranged at corresponding sensor positions configured around the lateral periphery of the arc furnace in a plurality of different longitudinal positions and a plurality of different circumferential positions, (c) A computer system comprising one or more electronic processors and one or more digital storage media coupled thereto, wherein the computer system is structured, connected, and programmed to (i) receive corresponding signals from the magnetic field sensors indicating magnetic field components measured at a plurality of corresponding sensor locations; (ii) receive signals indicating the magnitude of the primary current and the furnace voltage across the electrode and the ingot; (iii) detect a drip short between the electrode and the ingot based on a measured transient deviation of the primary current or the furnace voltage indicating a drip short; and (iv) calculate an estimated transverse position of the detected drip short in the gap based on at least two or more partial magnetic field components measured at the time of the detected drip short. A device equipped with the following features.

2. The apparatus according to claim 1, wherein the computer system is further structured, connected, and programmed to calculate estimated transverse positions for a plurality of detected drip shorts and to calculate the transverse spatial distribution of the plurality of estimated drip short positions.

3. The apparatus according to claim 2, wherein the computer system is further structured, connected, and programmed to (i) receive corresponding signals from the magnetic field sensor indicating magnetic field components measured at a plurality of corresponding sensor locations, and (ii) calculate an estimated transverse position or estimated transverse distribution of the one or more primary electrical discharges in the gap based on at least a portion of two or more of the measured magnetic field components.

4. The apparatus according to claim 3, further comprising one or more magnetic field sources positioned at corresponding source positions configured around the lateral peripheral portion of the arc furnace and configured to apply corresponding applied magnetic fields having corresponding non-zero components oriented transversely over at least a portion of the arc furnace including the gap, wherein the computer system is further structured, connected, and programmed to (i) generate one or more applied magnetic field control signals based at least partially on the transverse spatial distribution of the estimated drip-short locations, or on one or both of the estimated transverse locations or estimated transverse distributions of the one or more primary electrical discharges, and (ii) transmit the one or more applied magnetic field control signals to the magnetic field sources to change, maintain, or control the location or distribution of the one or more primary discharges, thereby changing, maintaining, or controlling the transverse spatial distribution of the estimated drip-short locations.

5. (a) A first longitudinal electrical conductor and a second longitudinal electrical conductor positioned end-to-end within a current-containing volume through which a primary current flows (i) through at least portions of the first conductor and the second conductor, and (ii) through one or more transverse localized current segments spanning a gap separating the first conductor and the second conductor, wherein the one or more current segments are movable in two transverse dimensions within the gap, and the first and second longitudinal electrical conductors flow primarily in the longitudinal direction as one or more transverse localized current segments, (b) (i) configured to measure magnetic field components or magnetic field magnitude in one or more spatial dimensions, and (ii) arranged at corresponding sensor positions configured around the lateral periphery of the current-containing volume in a plurality of different longitudinal positions and a plurality of different circumferential positions, (c) A computer system comprising one or more electronic processors and one or more digital storage media coupled thereto, wherein the computer system is structured, connected and programmed to (i) receive corresponding signals from the magnetic field sensors indicating magnetic field components measured at a plurality of corresponding sensor locations, and (ii) calculate an estimated transverse spatial distribution of current segments in the gap, or current in or through one or both of the first conductor and the second conductor, based on at least a portion of two or more of the measured magnetic field components. A device equipped with, (d) The current-containing volume is the internal volume of the remelting furnace, the first conductor is the electrode of the remelting furnace, and the second conductor is the ingot formed by the remelting process in the crucible of the remelting furnace. (e) The apparatus further comprises a corresponding additional sensor coupled to the furnace or positioned on or inside the furnace, wherein the corresponding additional sensor is configured to measure one or more or all of the following: (i) the longitudinal or transverse position or velocity of the electrode or one or more actuators coupled to the electrode; (ii) the weight of the electrode; (iii) the magnitude or variation of the operating current; (iv) the difference between the operating current and the primary current; (v) the voltage drop or variation between the electrode and the ingot; (vi) the electrical resistance across the gap or variation thereof; (vii) the temperature inside the furnace; (viiii) one or more temperature gradients in or along the electrode, in or along the ingot, or along or around the crucible; (ix) the pressure or composition of the gas or vapor inside the furnace; (x) the optical spectral characteristic light emitted by the one or more current segments; or (xi) an image of the inside of the furnace.

6. A method employing the apparatus according to claim 5, wherein the method comprises: (i) transverse position or transverse distribution of one or more current segments, (ii) transverse position or transverse distribution of a plurality of drip shorts, (iii) angle or transverse position of the electrode in the crucible, (iv) distance across the gap between the electrode and the ingot, (v) surface profile of the electrode obtained by estimating the distance across the gap as a function of the transverse position of the current segments, (vi) presence or duration or location of one or more side arcs, (vii) one or A method comprising recording one or more of the following: (vii) the presence, duration, or location of multiple contraction arcs, glows, or long arcs; (viiii) the presence or location of cracks or defects in the electrode during the corresponding time portion of the remelting process that resulted in the ingot; (ix) the longitudinal shape of the electrode; (x) the gas pressure or composition in the furnace; (xi) the slag depth or composition in the furnace; (xi) the occurrence or location of a shelf collapse event into the molten pool; (xiiii) transient fluctuations of current, voltage, or electrical resistance across the gap; (xiv) the immersion depth of the electrode into the molten slag filling the gap; (xv) the measured magnetic field component; or (xvi) the applied magnetic field component.

7. A method employing the apparatus of claim 5, wherein the method, in response to one or more magnetic field components measured by one or more corresponding sensors during the remelting process, or one or more estimates calculated therefrom, (i) halt the remelting process; (ii) temporarily suspend and then resume the remelting process; (iii) reject or downgrade the ingot; (iv) reject or downgrade only selected portions of the ingot; (v) apply a magnetic field to change, maintain or control the transverse position or transverse distribution of one or more current segments in the gap; (vi) apply a magnetic field to change, maintain or control the transverse distribution of a plurality of drip shorts in the gap; (vii) change, maintain or control the transverse distribution of heat accumulated on the surface of the ingot. A method comprising: (vii) applying a magnetic field to attenuate or terminate a side arc, contraction arc, glow, or long arc; (ix) changing, maintaining, or controlling the distance between the electrode and the ingot across the gap; (x) changing, maintaining, or controlling the angular or transverse position of the electrode in the crucible; (xi) changing, maintaining, or controlling the voltage across the gap; (xi) changing, maintaining, or controlling the electrical resistance across the gap; (xiiii) changing, maintaining, or controlling the current flowing through the electrode and the ingot; (xiv) changing, maintaining, or controlling the immersion depth of the electrode in the molten slag filling the gap; or (xv) changing, maintaining, or controlling the gas pressure or composition in the furnace.

8. A method employing the apparatus described in claim 5, wherein the method is (a) During a remelting process using the remelting furnace, supplying an operating current to the furnace such that at least a portion of the operating current flows through the furnace as the primary current. (b) Using the plurality of magnetic field sensors, measuring the magnetic field component or magnitude in one or more spatial dimensions at some or all of the corresponding sensor locations as a function of time during the remelting process, (c) Using the corresponding additional sensors, measure, as a function of time during the remelting process, one or more or all of the following: (i) longitudinal or transverse position or velocity of the electrode or one or more actuators coupled to the electrode; (ii) weight of the electrode; (iii) magnitude or variation of the operating current; (iv) difference between the operating current and the primary current; (v) voltage drop or variation between the electrode and the ingot; (vi) electrical resistance across the gap or variation thereof; (vii) temperature inside the furnace; (viiii) one or more temperature gradients in or along the electrode, in or along the ingot, or along or around the crucible; (ix) pressure or composition of gas or vapor inside the furnace; (x) optical spectral characteristic light emitted by one or more current segments; (xi) immersion depth of the electrode in the molten slag filling the gap or variation thereof; or (xi) images of the inside of the furnace. (d) Using the computer system to (i) receive a signal indicating some or all of the magnetic field components measured in part (b), (ii) receive a signal indicating some or all of the quantities measured in part (c), and (iii) change, maintain or control one or more operating parameters of the furnace during the remelting process based at least in part on the received signals in part (b) or (c), or quantities or parameters calculated, estimated or derived therefrom, or (iv) generate and store a longitudinal map or three-dimensional map of the ingot produced by the remelting process based at least in part on the received signals in part (b) or (c), or quantities or parameters calculated, estimated or derived therefrom. Methods that include...

9. (a) During a remelting process using a remelting furnace, supplying an operating current to the furnace, wherein at least a portion of the operating current is supplied such that it flows as a primary current in the longitudinal direction, generally as one or more transverse localized current segments, each of which is movable in two transverse dimensions within the gap, and is a primary current in the longitudinal direction. (b) Using a plurality of magnetic field sensors positioned at corresponding fixed or movable sensor positions configured around the lateral periphery of the crucible at a plurality of different longitudinal positions and a plurality of different circumferential positions, to measure, as a function of time during the remelting process, the magnetic field component or magnitude in one or more spatial dimensions at some or all of the corresponding sensor positions, (c) Using corresponding sensors coupled to the furnace or positioned on or inside the furnace, as a function of time during the remelting process, (i) the longitudinal or transverse position or velocity of the electrode or one or more actuators coupled to the electrode, (ii) the weight of the electrode, (iii) the magnitude or variation of the operating current, (iv) the difference between the operating current and the primary current, (v) the voltage drop or variation between the electrode and the ingot, (vi) the electrical resistance across the gap or variation therein, (vi i) measuring one or more or all of the following: (vii) the temperature inside the furnace, (ix) one or more temperature gradients in or along the electrode, in or along the ingot, or along or around the crucible, (ix) the pressure or composition of the gas or vapor inside the furnace, (x) the optical spectral characteristic light emitted by the one or more current segments, (xi) the immersion depth of the electrode into the molten slag filling the gap or its variation, or (xii) an image of the inside of the furnace. (d) Using a computer system structured, connected, and programmed for this purpose, comprising one or more electronic processors and one or more digital storage media coupled thereto, to (i) receive signals indicating some or all of the magnetic field components measured in part (b), (ii) receive signals indicating some or all of the quantities measured in part (c), and (iii) change, maintain, or control one or more operating parameters of the furnace during the remelting process based at least in part on the received signals or quantities or parameters calculated, estimated, or derived therefrom, or (iv) generate and store a longitudinal map or three-dimensional map of the ingot produced by the remelting process based at least in part on the received signals or quantities or parameters calculated, estimated, or derived therefrom. Methods that include...

10. Based at least in part on the received signal, or on quantities or parameters calculated, estimated, or derived therefrom, during the remelting process, (i) halt the remelting process; (ii) temporarily suspend and then resume the remelting process; (iii) reject or downgrade the ingot, or only selected portions of the ingot; (iv) specify or recommend a specific post-melting treatment for the ingot, or only specific portions of the ingot; (v) apply a magnetic field to change, maintain, or control the transverse position or transverse distribution of one or more current segments in the gap; (vi) apply a magnetic field to change, maintain, or control the transverse distribution of multiple drip shorts in the gap; (vii) change, maintain, or control the transverse distribution of heat accumulated on the surface of the ingot. The method according to claim 9, comprising: (viii) applying a magnetic field to maintain or control; (ix) applying a magnetic field to attenuate or terminate a side arc, contraction arc, glow, or long arc; (ix) changing, maintaining, or controlling the distance between the electrode and the ingot across the gap, or the immersion depth of the electrode in the molten slag filling the gap; (x) changing, maintaining, or controlling the angular or transverse position of the electrode in the crucible; (xi) changing, maintaining, or controlling the voltage across the gap; (xi) changing, maintaining, or controlling the electrical resistance across the gap; (xiiii) changing, maintaining, or controlling the current flowing through the electrode and the ingot; or (xiv) changing, maintaining, or controlling the gas pressure or composition in the furnace.

11. The method provides, as a function of the longitudinal position along the ingot formed by the remelting process in the remelting furnace, (i) the transverse position or transverse distribution of one or more current segments, (ii) the transverse position or transverse distribution of a plurality of drip shorts, (iii) the angle or transverse position of the electrode in the crucible, (iv) the distance across the gap between the electrode and the ingot, (v) the surface profile of the electrode obtained by estimating the distance across the gap as a function of the transverse position of the current segments, (vi) the presence or duration or location of one or more side arcs, (vii) one or more contraction arcs, glows, or long arcs The method according to claim 9, comprising recording one or more of the following: (viiii) the presence, duration, or location of a crack; (ix) the presence or location of a crack or defect in the electrode during a corresponding time portion of the remelting process that resulted in the ingot; (ix) the longitudinal shape of the electrode; (x) the gas pressure or composition in the furnace; (xi) the slag depth or composition in the furnace; (xi) the occurrence or location of a shelf collapse event into the molten pool; (xiiii) transient fluctuations of current, voltage, or electrical resistance across the gap; (xiv) one or more magnetic field components; (xv) one or more applied magnetic field components; or (xvi) the immersion depth of the electrode into the molten slag filling the gap.

12. The method according to claim 11, wherein the map indicates remelting conditions, metal quality, or specified or recommended post-molten treatment as a function of longitudinal or three-dimensional positions within the ingot.

13. The computer system includes an artificial intelligence subsystem, a machine learning subsystem, or a neural network, and the method is As training data, (i) the received signals from parts (b) and (c) for multiple remelting processes, and (ii) observed or measured metal quality as a function of the corresponding three-dimensional position in the ingot resulting from the multiple remelting processes, are provided to the artificial intelligence subsystem, the machine learning subsystem, or the neural network. During the subsequent remelting process, the received signals from parts (b) and (c) are provided to the artificial intelligence subsystem, the machine learning subsystem, or the neural network. Using the artificial intelligence subsystem, the machine learning subsystem, or the neural network, to modify, maintain, or control one or more operating parameters of the furnace during the subsequent remelting process. The method according to claim 9, further comprising:

14. The computer system includes an artificial intelligence subsystem, a machine learning subsystem, or a neural network, and the method is As training data, (i) the received signals from parts (b) and (c) for a plurality of remelting processes, and (ii) observed or measured metal quality as a function of the three-dimensional position within the corresponding ingot resulting from the plurality of remelting processes, are provided to the artificial intelligence subsystem, the machine learning subsystem, or the neural network. During the subsequent remelting process, the received signals from parts (b) and (c) are provided to the artificial intelligence subsystem, the machine learning subsystem, or the neural network. Using the artificial intelligence subsystem, the machine learning subsystem, or the neural network, generate and store a map of the ingot resulting from the subsequent remelting process, wherein the map indicates remelting conditions, metal quality, or specified or recommended post-melting treatment as a function of longitudinal or three-dimensional positions within the ingot. The method according to claim 9, further comprising:

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