WO2024100665A1 - Open-ring magnetic-flux-concentrator based heating system - Google Patents

Abstract

A heating system for heating a working area of an electrically conductive metallic workpiece includes an induction coil arrangement having at least one induction coil arranged with one or more turns defining at least one core to produce a magnetic field. A magnetic-flux-concentrator (OMFC) is positioned, in part, within the at least one core and has a shape with two open ends and a gap region between the two open ends of the OMFC. The OMFC directs the magnetic field crossing the gap region to graze the electrically conductive metallic workpiece below the gap region, to induce heating in a heated region in the electrically conductive metallic working area.

Description

OPEN-RING MAGNETIC-FLUX-CONCENTRATOR BASED HEATING SYSTEM

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from US provisional patent application 63/382,896, filed November 9, 2022, which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to magnetic induction generally and to induction coil heating systems in particular.

BACKGROUND OF THE INVENTION

[0003] Heating electrically conductive metallic materials is an important industrial process. For example, heating is utilized in surface treatment of metals (to release stress and control crystalline structure) and for melting metals, whether in bulk or locally, such as in welding.

[0004] Induction heating is a method for heating electrically conductive metallic materials, namely metals or semiconductors, which is capable of non-contact, flameless and energetically efficient heating of such conductive substrates.

[0005] As described in the Wikipedia article “Induction heating”, stored at https:// en.wikipedia.org /wiki /Induction_heating, an induction coil is driven by an alternating current (AC), to produce a rapidly alternating electromagnetic field, and is suspended over an electrically conductive metallic material. The rapidly alternating magnetic field penetrates the electrically conductive metallic material and generates electrical currents, known as eddy currents, within the electrically conductive metallic material. Such electrical currents flow through the resistance of the material, and produce a heated region of the substrate by Joule heating.

[0006] Electrical currents tend to flow on the outer surfaces of electrical conductors, a tendency known as the ‘skin effect.” Induced electrical currents act similarly, and such eddy currents as described hereinabove are generated on the outer surface of electrically conductive metallic materials, under the induction coil. During induction heating, the skin effect causes the heating caused by the induced electrical current, to be localized on the outer surface of the conductive material, under the induction coil. Any heating profile deeper within the substrate will be the result of mechanical heating of the substrate by the surface induction heating profile, rather than by electromagnetically induced heating as a result of eddy currents deeper in the material. The ‘skin effect’ is described in the Wikipedia article “Skin Effect”, stored at https:// en.wikipedia.org/ wiki/ Skin_effect.

[0007] The induced electrical currents themselves generate another magnetic field, which acts to oppose the magnetic field produced by the induction coil. Hence, such magnetic fields produced by such eddy currents act to electromagnetically shield the electrically conductive metallic material from the penetrating effects of the magnetic field produced by the induction coil, which becomes limited to near the surface of the substrate. Discussion of such ‘shielding’ may be found in the Wikipedia articles “Electromagnetic shielding”, stored at https:// en.wikipedia.org/ wiki/ Electromagnetic_shielding #Magnetic_shielding, and “Faraday cage” stored at https:// en.wikipedia.org/ wiki/ Faraday_cage.

[0008] As a result of the abovementioned induced currents, skin effect and electromagnetic shielding, induction heating coils generate heating profiles that are localized on the surface area of electrically conductive metallic substrates, and appear to only ‘graze,’ rather than deeply penetrate the surface of such substrates.

[0009] Typically, heating systems comprise of an inductor, typically a coil, an AC power supply, and an optional cooling system for the coil for high power, strong magnetic fields, high frequencies and high current systems and applications.

[0010] The coil geometry is matched to the desired heating application. For example, solenoid coils can be used for the heat treatment of rods, while hairpin coils can be used for flat surfaces.

[0011 ] Typically, the point of maximum heating of the surface is directly under or within a part or winding of the coil. Accessing the heated area typically requires removing the coil from the heated area.

[0012] Flux concentrators, typically materials with high magnetic permeability, are used to direct the magnetic flux within them by providing a path of lower reluctance than air, or whatever surrounds them, and can enhance the electromagnetic field where heating is desired.

SUMMARY OF THE PRESENT INVENTION

[0013] According to first aspect of the present disclosure, there is provided a heating system for heating a working area of an electrically conductive metallic workpiece, the system may include an induction coil arrangement that may include at least one induction coil arranged with one or more turns defining at least one core to produce a magnetic field; a magnetic-flux-concentrator (OMFC) positioned, in part, within the at least one core and having a shape with two open ends and a gap region between the two open ends of the OMFC, to direct the magnetic field within the OMFC, and to direct the magnetic field crossing the gap region to graze the electrically conductive metallic workpiece below the gap region, to induce heating in a heated region in the electrically conductive metallic working area; and an AC (alternating current) current source to supply AC current to the at least one induction coil.

[0014] The magnetic-flux-concentrator (OMFC) may be shaped as an uncomplete ring or as a horseshoe.

[0015] The OMFC may be oriented to form an unobstructed central region above the gap region, to allow line of sight access from above the heating system to the heated region.

[0016] The OMFC may be shaped to form an unobstructed central region above the gap region, to allow line of sight access from above the heating system to the heated region. [0017] The induction coil arrangement may be a single multi-tum solenoid wound around the OMFC. The induction coil arrangement may include two coil rings each wound around the OMFC. The induction coil arrangement may include multiple multi- tum coils, each of the multiple multi-tum coils defining a core. The induction coil arrangement may include one or more multi-tum coil wound around the OMFC. The induction coil arrangement may include a first coil arrangement with a first OMFC inducing heating at a first heated region and a second coil arrangement with a second OMFC inducing heating at a second heated region, wherein the second heated region may be located adjacent to the first heated region. The relative polarity of magnetic flux flowing through the first OMFC and through the second OMFC may be parallel or antiparallel.

[0018] The heating system may further include a cooling arrangement for cooling the induction arrangement. The the cooling arrangement may be a cooling jacket. The induction arrangement may include one or more hollow coils and the cooling arrangement may be arranged to circulate a coolant through the one or more hollow coils. [0019] The AC current may have an amperage of at least 1KA and a frequency of at least lOOKHz.

[0020] The heating system may further include a current source controller configured to control and adjust one or more of: current amplitude, current phase, and current frequency.

[0021] The heated region may not be a footprint of either the OMFC or the at least one induction coil. The geometry of the heated region may be a function of (1) a geometry of the coil arrangement, (2) a geometry of the gap region, (3) an orientation of the OMFC (4) a height of a bottom part of the OMFC above the electrically conductive metallic workpiece; and (5) a number of coil turns in the at least one coil arrangements.

[0022] According to another aspect of the present disclosure, there is provided a casting system for casting a metallic object by constructing a plurality of production layers forming a vertical stack, wherein the production layers have mold regions, wherein the production layers have object regions defined by the mold regions, and wherein a current production layer is constructed upon a top surface of a previous production layer of the vertical stack, the system may include a mold construction system operative to construct a mold region of the current production layer; a metal deposition system operative to construct an object region of the current production layer; a build table for supporting the vertical stack of production layers; and a controller for controlling at least the mold construction system and the metal deposition system, wherein the metal deposition system may include an induction system according to the first aspect of the present disclosure. [0023] The metal deposition system may be configured to deposit molten metal on the previous production layer through the gap of the heating system. The casting system controller may be further configured to control the heating system so as to heat the previous production layer before molten metal deposition, during molten metal deposition or after molten metal deposition.

[0024] The casting system may further include a temperature sensor and/or a height sensor for measuring, through the gap region of the heating system, a temperature and/or a relative height of the working area, and the controller may be further configured to control the metal deposition system in response to readings of the temperature sensor and/or the height sensor.

[0025] According to yet another aspect of the present disclosure, there is provided a surface heating and ablation system for treating a surface of an electrically conductive workpiece that may include a movable surface heater, at least one sensors, and a controller, the controller may be configured to control one or more operational parameters of the surface heater in response to readings of the at least one sensor, wherein the surface heater may be a an heating system according to the first aspect of the present disclosure. The sensors may be a temperature sensor, a distance sensor or a camera. The one or more operational parameters of the surface heater may be one or more of: a distance of the surface heater system from the electrically conductive metallic workpiece, voltage, current amperage, current phase, and current frequency.

[0026] The surface heating and ablation system may further include a motion system for providing a relative movement along a pre-defined heating path between the surface heater and the electrically conductive workpiece, and wherein the controller may be further configured to controlling a pace of the relative movement along a pre-defined heating path in response to readings of the one or more sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

[0028] Figs. 1A and IB are schematic illustrations of a circular open-ring magnetic-flux- concentrator (OMFC) based, magnetic induction heater (OMIH), and a rectangular openring magnetic-flux-concentrator based induction heater (OMIH) constructed and operative according to embodiments of the invention;

[0029] Fig. 1C and ID are schematic illustrations of the magnetic fields produced by the OMIH of Figs. 1A and IB, respectively;

[0030] Fig. 2A is a schematic illustration of an embodiments of the OMIH comprising a pair of current loops.

[0031] Fig. 2B is a schematic illustration of an embodiments of the OMIH comprising a two stacks of current loops;

[0032] Fig. 3A is a schematic illustration of the OMIH of Fig. 1A, comprising a tilted circular OMFC;

[0033] Fig. 3B is a schematic illustration of an OMIH comprising a modified ‘notched’

OMFC; [0034] Figs. 4A, 4B and 4C are schematic illustrations the magnetic fields produced by different gap geometries of the OMFC of Fig. 1A;

[0035] Figs. 5A and 5B are schematic illustrations of alternative embodiments of the OMIH, each comprising adjacently positioned OMIHs;

[0036] Figs. 6A and 6B are schematic illustrations of an alternative OMIH, comprising orthogonally positioned OMIHs;

[0037] Fig. 7 is a schematic illustration of an exemplary OMFC based OMIH system;

[0038] Fig. 8 is a schematic illustration of an additive casting system that incorporates the OMIH system of Fig. 7 ; and

[0039] Fig. 9 is a schematic illustration of a surface heating and ablation system that incorporates the OMIH system.

[0040] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0041] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention. [0042] Applicant has realized that, in heating systems used for localized heating, the position of the heated region is a projection, or footprint, under the induction coil. To heat an area of the substrate outside of the coil footprint requires the induction heater coil to move around the surface of the substrate.

[0043] Applicant has realized that the footprint profile of the heated region is fixed according to the design and implementation of the heating coil and its position with respect to the workpiece.

[0044] Likewise, Applicant has realized that, to gain access to the heated region after heating, for example to provide material to the heated region or to perform additional surface treatment, requires the induction heating coil to be moved out of the way.

Open-Ring Magnetic-Flux-Concentrator based Induction Heater

[0045] Applicant has realized that by using an open-ring, semi-ring, open-loop or ‘horseshoe’ shaped flux concentrator together with a solenoid, a heated region may be located under a gap region between the open ends of the flux concentrator.

[0046] Applicant has realized that by positioning the heated region under a gap created by the geometry of the flux concentrator, line of sight may be maintained to the heated region. Such a line of sight may be used, for example, to allow a sensor to measure the temperature of the heated region, and/or a material to be added to the heated region without removing the induction heater and disrupting the heating or controlled cooling process.

[0047] Applicant has realized that, especially for high-power applications (e.g., AC current with an amperage of at least 1KA and a frequency of at least lOOKHz), magnetic field concentration to a pre-defined heating region/spot will increase energy efficiency and can provide better control over surface treatment with induction heating. [0048] Reference is made to Figs. 1A and IB which are schematic illustrations of two embodiments of magnetic induction heaters (OMIH): a circular OMIH 10 and a rectangular OMIH 11, respectively, constructed and operative according to an embodiment of the invention.

[0049] OMIH 10 comprises a circular shaped open-ring magnetic flux concentrator (OMFC) 101 and a solenoid 102. Solenoid 102 is wound around OMFC 101 such that OMFC 101 resides in the core of solenoid 102. OMFC 101 may have a gap region KR between open ends 104 of OMFC 101. Open ends 104 may be suspended a distance D above a surface or workpiece 12.

[0050] Solenoid 102 may produce a magnetic field MS, which is represented in the following figures as magnetic field lines. These magnetic field lines of field magnetic MS may be concentrated by, and flow through circular OMFC 101. This is due to the lower path of reluctance through OMFC 101 as compared to the space around OMFC 101. The resulting addition of a plurality of magnetic field lines of magnetic field MS within OMFC 101 results in a higher concentration of magnetic field MS within OMFC 101, hence the name magnetic flux concentrator. Concentrated magnetic field MS flows through OMFC 101, and may pass across and around gap region KR. Fig. 1C is a schematic illustration of magnetic field MS produced by OMIH 10. In the illustration, the thickness of magnetic field lines MS denotes relative magnetic field strength, thicker lines representing higher relative magnetic field strength and thinner lines representing lower relative magnetic field strength.

[0051] It should be noted that the illustration of magnetic field MS shown in Fig. 1 A has been reduced to the area around gap region KR for clarity. Magnetic field MS is more fully illustrated in Fig. 1C. [0052] It will be appreciated that the size of gap region KR and the distance between open ends 104 may not be fixed and may vary according to a pattern such as, but not limited to, a discrete size, a plurality of discrete sizes, a plurality of continuous sizes, or a plurality of scanning sizes.

[0053] Depending on the strength of magnetic field MS and on the distance D, a portion of magnetic field MS may penetrate work surface 12 beneath gap region KR and between open ends 104. As is known, magnetic fields induce eddy currents in electrically conductive metallic materials like work surface 12, and the ‘skin affect’ will cause induced current flow at the surface of work surface 12. There is a measurable increase in temperature caused by these induced currents, on the surface of work surface 12 producing a heated region Hl .

[0054] The geometry and temperature profile of heated region Hl may depend on the level of induced current. It will also be appreciated that heated region Hl may have a geometry that is not a footprint of either circular OMFC 101 or solenoid 102.

[0055] It is also known that these induced eddy currents produce another magnetic field which opposes magnetic field MS. This second induced magnetic field shields magnetic field MS from penetrating deeper than the surface of work surface 12.

[0056] It should be noted that as distance D decreases, the geometry of heated region Hl will approach the geometry of gap region KR. It will be appreciated that, by adjusting distance D and the width of gap region KR, the geometry and intensity of heated region Hl may be affected.

[0057] The geometry of the heated region is ,thus, a function of (1) a geometry of the coil arrangement, (2) a geometry of the gap region, (3) an orientation of said OMFC, (4)

Distance D - the height of a bottom part of said OMFC above the electrically conductive metallic workpiece; and (5) the number of coil turns in said at least one coil arrangements.

[0058] In some embodiments, heated region Hl may be of interest and other heated regions may be considered spurious or unwanted, or vice-versa. In some embodiments, unwanted heated regions may be located far away from the heated region of interest, and in other embodiments nearby. It will be appreciated that most of the effective heating generated by OMIH 10 may be directed toward the heated region of interest Hl, while minimizing residual heating to the unwanted heated regions.

[0059] As mentioned hereinabove, circular OMFC 101 may provide a path of lower reluctance to magnetic field MS, than the path through the air space around and within solenoid 102. Similarly, when distance D between circular OMFC 101 and conductive workpiece 12 is similar to a distance KD between open ends 104 of circular OMFC 101, magnetic flux MS may flow from open ends 104 through workpiece 12, rather than flow around and across gap region KR. This may be because workpiece 12 may provide a lower path of reluctance than air in and around gap region KR.

[0060] It will be appreciated that inductive heating may be performed at distance D from the lowest point of semi-ring flux concentrator 101 and work surface 12, and that reducing distance D may increase the heating effect at heated region Hl, as more magnetic field MS may penetrate workpiece 12, inducing higher eddy currents.

[0061] It will be appreciated that distance D may not be fixed and may vary according to a pattern such as, but not limited to, a discrete distance, a plurality of discrete distances, a plurality of continuous distances, or a plurality of scanning distances. For certain applications, for example as will be discussed with reference to Fig. 8, the distance D may range between 2 to 12 millimeters. [0062] Solenoid 102 may be constructed from any suitable material known in the art, such as, but not limited to, water cooled metal tubes or wire-wound coils. Solenoid 102 may be connected to any suitable power source known in the art. Solenoid 102 may also be connected to any suitable cooling system known in the art.

[0063] OMIH 10 may be fed with AC current with an amperage of at least 1KA and a frequency of at least lOOKHz. OMIH 10 may further comprise a current source controller (not shown) configured to control and adjust one or more of: current amplitude, current phase, and current frequency.

[0064] In an alternate embodiment, rectangular OMIH 11 comprises a rectangular OMFC 111 (“horseshoe”) and a solenoid 112, as shown in Fig. IB. Similarly to OMIH 10, OMIH 11 may produce a magnetic field MSR. Fig. ID is a schematic illustration of magnetic field MSR produced by OMIH 11. In the illustration, the thickness of magnetic field lines MSR denotes relative magnetic field strength, thicker lines representing higher relative magnetic field strength and thinner lines representing lower relative magnetic field strength.

[0065] It will be appreciated that the shape of an OMFC may be any shape that accommodates a solenoid and has a gap region. The geometry of an OMFC may affect the size, shape and intensity of the heated region on work surface.

Alternate Current Source Embodiments

[0066] It will be appreciated that solenoid 102 may be replaced in other embodiments with any arrangement of induction loops. Such arrangements may be for example, but not limited to, individual coil turns, or multiple coil-turns, that may be connected to one or more AC power supplies. [0067] It will be appreciated that the direction of current flows in such induction loop(s) may affect the intensity and shape of any magnetic flux produced by such induction loops. Figs. 2A and 2B are schematic illustrations of alternate embodiments of OMIH 21 and OMIH 22 respectively. OMIH 20 may be construed with two ring-like induction coils placed around a horse-show core. It will be appreciated that, to maximize a magnetic field MSS produced by single current loops SCL1 and SCL2, the direction of current flow must be opposite between single current loops SCL1 and SCL2 (i.e. of opposite chirality). Similarly in Fig. 2B, to maximize a magnetic field MSM produced by two individual solenoids MCL1 and MCL2 around the horse show core, the direction of current flow must be opposite between multiple current loops MCL1 and MCL2.

[0068] As with solenoid 102, current loops SCL1, SCL2, MCL1 and MCL2 may be constructed from any suitable material known in the art, such as but not limited to water cooled metal tubes, or wire-wound coils. Current loops SCL1, SCL2, and solenoids MCL1 and MCL2 may be connected to any suitable power source , or multiple power sources (not shown), known in the art. Current loops SCL1, SCL2, and solenoids MCL1 and MCL2C may also be connected to any suitable cooling system known in the art (not shown).

[0069] It will also be appreciated that the polarity and/or frequency of the AC current supplied to multiple current loops (such as SCL1 and SCL2) and solenoids (such as MCL1 and MCL2) may be chosen to minimize cross talk between them. Cross talk is when one of the loops or solenoids induces a current in the other loops or solenoid by the magnetic field of one coil causing induction in the other coil. Cross talk and how to mitigate it is known in the art. Line of Sight Access

[0070] Applicant has realized that in prior art induction heating, to gain access to the heated region after heating, for example, to provide material to the heated region or to perform additional surface treatment, requires the induction heating coil to be moved out of the way.

[0071] Applicant has realized that, by positioning the middle region of the flux concentrator or adjusting the shape of the middle region of the flux concentrator, an unobstructed central region may be made above the gap region, such that a line of sight (LOS) may be maintained through the unobstructed central region, the gap region, and the below gap region to the heated region of the workpiece. Such a line of sight may be used, for example, to allow a sensor to measure the temperature of the heated region, and/or a material to be added to the heated region without removing the induction heater and disrupting the heating or cooling process.

[0072] Applicant has realized that prior art induction coil heating systems, especially those with a small working distance D, may require that an induction coil heater be moved in order for a sensor or surface treatment unit that requires line of sight access to a working area to operate.

[0073] Reference is made to Figs. 3A and 3B, which are schematic illustrations of preferred embodiments of the present invention OMIH 30 and OMIH 31, respectively, with direct line of sight access (LOS) from above the induction heater to heated regions H30 and H31 of a working area W30 or W31.

[0074] OMIH 30 is similar to OMIH 10 (shown in Fig. 1 A) in all respects other than the orientation of open-ring magnetic-flux-concentrator 301 to allow line of sight access to working area 31. To form an unobstructed central region UR30, above a gap region

KR30, circular OMFC 301 may be tilted as shown in Fig. 3A.

[0075] It will be appreciated that line of sight access may not need to be perpendicular to work surface, and line of sight access may be possible for some applications via gap region KR30, without tilting or otherwise modifying circular OMFC 30, or other magnetic concentrator implementations detailed hereinbelow.

[0076] OMIH 31, in Fig. 3B, is also similar to OMIH 10 in all respects other than that notched OMFC 311 has been structurally modified with a notch of width N31 to allow line of sight access (LOS) to heated region H31 of working area W31 from above notched OMFC 311. It will be appreciated that any structural modification may be made to notched OMFC 311 that leaves an unobstructed central region UR31, above gap region KR31, and is not limited to the design shown in Fig. 3B.

[0077]

[0078] Such line of sight access could be used, for example, for a sensor S suspended above or in any of unobstructed central regions UR30 or UR31, gap regions KR30 and KR31, and below gap regions KR30 and KR31, to measure the temperature of heated regions H30 and H31. In another embodiment, a surface treatment unit (not shown) may be suspended above or in any of unobstructed central regions UR30 or UR31 , gap regions KR30 and KR31, and below gap regions KR30 and KR31, to provide surface treatment to heated regions H30 and H31. Another application may be to enable a laser to operate through gap regions KR30 and KR31 to provide surface treatment to heated regions H30 and H31 concurrently with heating. Heating systems according to embodiments of the invention may facilitate surface treatment concurrently with heating, if such heating systems would be incorporated, for example, in a high rate material deposition system as described in US Patent publication US2016/0271732A1, dated September 22, 2016 and additive casting system as described in PCT Patent publication WO2019053712A1, dated March 21, 2019.

[0079] It will also be appreciated that the invention is not limited by the type of unit suspended above or in any of unobstructed central regions UR30 or UR31, gap regions KR30 and KR31, and below gap regions KR30 and KR31. For example, a material depositor (not shown) may be suspended above or in any of the abovementioned regions, to deposit material, in the form of solids (e.g. powder), liquids, gases or plasma, on top of heated regions HH30 and H31.

[0080] It will also be appreciated that applications that do not require access to heated areas from above the magnetic concentrator, may gain access to heated areas at an angle less than 90 degrees to the surface of worksurface 12. These application may or may not require the flux contractor to be modified or tilted to enable such angled access.

[0081] It will be appreciated that line of sight access may not be fixed and may vary according to a pattern such as, but not limited to, a discrete line of access, a plurality of discrete lines of access, a plurality of continuous lines of access, or a plurality of scanning lines of access.

OMFC Gap Region Geometry

[0082] Applicant has realized that the geometry of the gap region of an OMFC may affect the magnetic field profile produced in and around the gap region of an OMFC. Reference is made to Figs. 4 A to 4C which are simulations of the magnetic fields resulting from OMFCs with different gap region profiles. In Fig. 4A, OMFC 040 of OMIH 40 has an unbiased gap region geometry in gap region KR40, formed by open ends 104 with parallel surfaces 141 and 142. In Fig. 4B, OMFC 041 of OMIH 41 has an outer-biased gap region geometry in gap region KR41, formed by open ends 104 with non-parallel surfaces 143 and 144. Surfaces 143 and 144 are closer at the side of gap region KR41 towards the outside of OMFC 041. In Fig. 4C, OMFC 042 of OMIH 42 has an inner-biased gap region geometry in gap region KR42, formed by open ends 104 with non-parallel surfaces 145 and 146. Surfaces 145 and 146 are closer at the side of gap region KR42 towards the inside of OMFC 042.

[0083] In the illustrations, the thickness of the magnetic field lines denotes relative magnetic field strength, thicker lines representing higher relative magnetic field strength and thinner lines representing lower relative magnetic field strength.

[0084] Applicant has realized that by adjusting the gap region geometry, the resulting magnetic field in the gap region and projected around the gap region may be controlled, and by increasing the distance between surfaces, a magnetic field strength may be reduced.

[0085] It will be appreciated that gap region geometry is not limited to unbiased, inner- biased and outer-biased profiles. Gap region geometries may range from simple parallel or unbiased geometries to complex 3 dimensional surface geometries. Such complex geometries may produce complex magnetic field profiles which may induce complex heated region profiles on work surfaces.

[0086] It will also be appreciated that the gap region geometry may not be fixed during a heating cycle, and may change dynamically in response to sensor, programmatic, or operator input. Gap geometry may have a discrete geometry, a plurality of discrete geometries, a plurality of continuous geometries, or a plurality of scanning geometries. Multiple Open-Ring Magnetic Flux Concentrators

[0087] Applicant has realized that, by combining multiple OMIHs, heated region profiles may be expanded beyond the heating limitations of a single OMIH.

[0088] Reference is made to Fig. 5A which details an alternative embodiment, labeled OMIH 50A, and to Fig. 5B which details an alternative embodiment, labeled OMIH 50B, each comprising adjacently positioned OMIHs. In Fig. 5A, OMIH 50A comprises a first OMIH 51 placed adjacently along a line TU to a second OMIH 52, such that their respective heating zones H51 and H52 are adjacent. The phases of a magnetic field MS51 produced by OMIH 51 and a magnetic field MS52 produced by OMIH 52 may be the same, and such parallel aligned electromagnetic fields may merge to form a single large heated area H50A.

[0089] It will be appreciated that the shape of OMFC 051 of OMIH 51 and OMFC 052 of OMIH 52 may be designed such that heated areas H51 and H52 may be positioned close to one another, so as to maximize the size of combined heated region H50A. It will also be appreciated that the phase and/or frequency of the AC current supplied to each of OMIH 51 and 52 units may be chosen to minimize cross talk between heating units, as is known in the art.

[0090] It will be appreciated that such combined heating affects may provide for a combined heating profile that overcomes heating limitations to individual OMIH units 51 and 52, such as pixilated control of the heating region itself, and a larger combined heated area.

[0091] In Fig. 5B, similar to Fig. 5A, a first OMIH 53 is placed adjacently to a second OMIH 54 such that their respective heating zones H53 and H54 are proximal. However, in this embodiment, the phase of one of the magnetic fields, in this case magnetic field MS54 of OMIH 54, is reversed relative to that of magnetic field MS53 of OMIH 53, but either magnetic field could be reversed relative to the other. In contrast to the case above where heated regions H51 and H52 joined to form a single heated region 50A, in this case, parallel electromagnetic fields with opposite phase may interfere destructively, and a blind spot BS may be formed between heated areas H53 and H54, where no induction heating may take place.

[0092] It will be appreciated that, by controlling the relative polarities of parallel electromagnetic fields, the profile and temperature of a heated region may be controlled without moving or removing induction heaters, while maintaining line of sight to heated regions.

[0093] Reference is made to Figs. 6 A and 6B which detail an alternative embodiment, labeled OMIH 60, and to Fig. 6C which details an alternative embodiment, labeled OMIH 61, both comprising orthogonally positioned induction heating units. In Figs. 6A and 6B, an OMIH 64 comprising an OMFC 064 and a solenoid S64 may produce a magnetic field MS64. OMIH 64 may be positioned along a plane PQ. A second OMIH 65 comprising an OMFC 065 and a solenoid S65 may produce a magnetic flux MS65. OMFC 065 may be positioned along a plane RS. Planes PQ and RS may be orthogonal. When operated simultaneously, magnetic field MS64 from OMIH 64 and magnetic field MS65 from OMIH 65 may interfere to create a combined magnetic field parallel to diagonal axis Z60, whereby the flux density at the center heated area H60 may be the result of the additive nature of heated regions H60A and H60B produced by electromagnetic fields MS64 and MS65 (similar to those in Fig. 5A). It will be appreciated that such additive heating may increase the rate of heating of metal surface

12 compared to a single heating unit. [0094] In Fig. 6C, OMIH 64 and OMIH 65 of Figs. 6A and 6B may be positioned as in Fig. 6B. However in this embodiment, the phase of magnetic field MS65R is reversed compared to the phase of magnetic field MS65 in Figs. 6A and 6B. When operated simultaneously, magnetic field MS64 from OMIH 64 and magnetic field MS65R from OMIH 65 may interfere to create a combined magnetic field parallel to diagonal axis Z61 (at a 90 degree offset from diagonal axis Z60 of Fig. 6B), whereby the flux density at the center heated area H61 may be the result of the additive nature of heated regions H61A and H61B produced by electromagnetic fields MS64 and MS65R.

[0095] It will be appreciated that, unlike embodiments OMIH 50A and OMIH 50B discussed hereinabove, in embodiments OMIH 60 and OMIH 61, regardless of the relative phase of magnetic fields, the resulting heated region is always additive, and no blind spot may be produced.

OMIH System

[0096] Reference is made to Fig. 7 which illustrates an exemplary OMFC based induction heater system (OMIH system) 100. OMIH system 100 comprises OMIH 30 (from Fig. 3A), a power controller 1002, a cooling controller 1003, an OMIH position controller 1004, a workpiece position controller 1005 and an OMFC gap geometry controller 1006.

[0097] It will be appreciated that OMFC 301 of OMIH system 100 may have a gap region KR30 between open ends 104 of OMFC 301, and may be designed or oriented to have an unobstructed central region UR30 above gap region KR30. The lowest extreme of OMFC 301 may be a distance D above working surface W30. [0098] Unobstructed central region UR30 and gap region KR30 may provide uninterrupted line of sight access from above OMIH system 100 to heated region H30 situated below OMIH system 100 on work surface W30.

[0099] It will be appreciated that OMIH system 100 may comprise any of the abovementioned OMIH embodiments 10, 11, 30, 31, 40, 41, 42, 50A, 50B, 51, 52, 53, 54, 60, 61, 64, and 65.

[00100] Power controller 1002 may independently control a power source (not shown), to control the amplitude, the frequency, and the relative phase of current supplied to solenoid 302.

[00101] Cooling controller 1003 may control a coil cooler (not shown) that provides coolant to solenoid 302 and/or OMFC 301.

[00102] OMIH position controller 1004 may control the position of flux concentrator 301, in any of the six degrees of freedom on a path MFC, via OMIH positioner(s) (not shown), with respect to the position of work piece W30, and hence may control the size of distance D.

[00103] Workpiece position controller 1005 may control the position of workpiece W30 in any of the six degrees of freedom on a path MWP, via workpiece positioner(s) (not shown), with respect to flux concentrator 301, and hence control the size of distance D.

[00104] OMFC gap geometry controller 1006 may control the gap geometry of OMFC 301 ranging from extreme inner-bias to extreme outer-bias, via open end positioner(s) (not shown).

[00105] It will be appreciated that controllers 1002, 1003, 1004, 1005 and 1006 may adjust outputs in order to, for example, adjust the heated region H30 to a desired temperature and profile; adjust the position of the current heating spot H30 (assuming that the desired heated region is larger than the heating spot size of OMIH 30); adjust the height of flux concentrator 301 from the workpiece W30; or produce any other desired outcome.

[00106] It will also be appreciated that controllers 1002, 1003, 1004, 1005 and 1006 may adjust outputs in response to operator intervention, as well as automatically in response to, for example, temperature inputs from sensor S, suspended above OMIH system 100, with line of sight to heated region H30; power levels from power supply (not shown); temperature readings of the cooling water running through the coils (not shown), the strength and orientation of magnetic field MS; and/or measurements of distance D between flux concentrator 301 and worksurface W30.

It will be appreciated that controllers 1002, 1003, 1004, 1005 and 1006 may adjust outputs in a dynamic scanning and/or continuous mode during heating, as well as between static heating states.

Casting System

[00107] It will be appreciated that OMIH system 100 may operate as a workpiece heater for a metal casting system. An exemplary additive casting system 300 is described in PCT Patent Applications publication numbers WO2019053712A1, WO2022243921A, and W02023002468, all of which are incorporated herein by reference. It will be appreciated that OMIH system 110 may operate as a workpiece heater (surface heater) for a casting system. Fig. 8, to which reference is now made, illustrates an additive casting system 300 that may incorporate MIH system 110 as described hereinabove. [00108] Additive casting system 300 comprises a movable mold dispensing unit 230, a movable metal deposition system 220, a build table 216, and a controller 253.

[00109] System 300 may be configured to additively produce a vertical stack of multiple production layers, one currently-produced production layer 201 after the other, on build table 216. For each currently-produced production layer 201, movable mold dispensing unit 230 moving along a mold path MP, at a working distance Wd above currently-produced production layer 201, may construct mold regions 202. Mold regions 202 include at least one cavity 203 into which the molten metal may be deposited.

[00110] Once mold region/s 202 of a production layer 201 are complete, movable deposition unit 220 may deposit molten metal 204 along a deposition path DP, at working distance Wd above currently -produced production layer 201, in working areas in object regions 205 to be fabricated. Working distance Wd may be dictated by the height of mold region 202 of production layer 201, and may typically be 2-20mm and specifically 4- 8mm.

[00111] Movable deposition unit 220 comprises a movable molten metal deposition module 206 for depositing molten metal 204 in multiple working areas in object regions 205. One working area in the currently-produced object region in shown in Fig. 8 as heated region HR. Molten metal may be deposited as a single drop, a plurality of drops or as a stream 204. It will be appreciated that build table 216 may be moved relative to movable mold dispensing unit 230 and/or to movable deposition unit 220 along worktable path WTP.

[00112] The working area (heated region HR) may be heated prior to molten metal deposition (a process known as pre-heating), during deposition, and/or after molten metal deposition (a process known as post heating). Thus, the casting system employs area heating systems, e.g., heating systems.

[00113] In prior art casting systems that imply prior art induction systems for area heating, the working area receiving the molten metal to be deposited must be placed beneath the area heater for heating, and beneath the molten metal depositor for receiving the deposited molten metal. This is achieved e.g., by moving the area heater/s and molten metal depositor/s over the object region and depositing the molten metal on a specific working area once the area heater passes it.

[00114] By incorporating any of the OMIH systems of the present disclosure, the heated region HR can be heated concurrently with the deposition of molten metal into the heated region. This enables operational flexibility. For example, the amount of heating provided to the working area may be reduced as there is no need to compensate for the cooldown of the working area while the heaters move out of the area and the molten metal depositor moves into place. Further, the geometry of the superimposed magnetic field generated by the OMIH, which dictates the geometry of the heated region HR, may be adjusted and controlled by controlling various operational parameters of the OMIH. Further still, accurate measurements, e.g., temperature measurements and height measurements of e.g., the depositor, the OMIH and additional elements above the working area, may be measured concurrently with molten metal deposition.

[00115] As a non-limiting example, the casting system may be used for casting gray iron objects of small, medium and large part sizes and masses; the production layers may range in thickness from about 2 millimeters to 12, 15 and 20 millimeters. The grey iron source (e.g., a grey iron rod) may be heated to melting; and the surface of previously produced grey iron regions may be heated to melting (for example, heated to 1100-1300 C deg.); The working areas to be heated may have a length (along the deposition path) in a range of 3 to 50mm, a width equal to or larger than a diameter of the molten metal deposited by the molten metal depositor (2- 12mm), and a depth in a range of 1 to 20mm; the area heaters, realized as induction heaters, may operate at high AC current of at least 1 KA (Kilo Ampere) at a frequency of at least 100 KHz (Kilo Hertz).

[00116] Thus, according to aspects of the invention, movable deposition unit 220 further comprises OMIH system 100 that may be attached or coupled to deposition module 206 so as to heat working area 212 and to produce heated region HR accessible through an unobstructed central region UR100, and a gap region KR100 between open ends OE100 of OMFC FC 100.

[00117] It will be appreciated that heated region HR may have a static or a dynamic profile, as controlled by a controller 253. Controller 253 may adjust controllable aspects of OMIH system 100 as described hereinabove. Controllable aspects may include voltage, current, phase, gap, gap geometry, and working distance as described hereinabove. As such, the shape, temperature and position of heated region may be fixed or vary dynamically during heating and cooling cycles.

[00118] Once heated region HR is at the desired temperature and dimensions, molten metal 204 may be deposited directly onto heated region HR.

[00119] In the embodiment illustrated in Fig. 8, deposition unit 220 may be moved laterally across the surface of the metal in a linear or other pattern, while molten metal 204 is deposited. The motion may be in a direction parallel to the axis connecting the centers of the coils or in a perpendicular direction. OMIH system 100 that is part of deposition unit 220 or otherwise coupled to deposition module 206 (for example, carried by a common motion unit, not shown), may follow the movement of deposition unit 220. [00120] It will be appreciated that OMIH system 100 may provide line of sight access from above OMIH system 100 to heated region HR, thereby to enable deposition module 206 to deposit molten metal 204 directly onto heated region HR, once heated region HR is at the desired temperature and dimensions.

[00121] Movable dispensing unit 230 and movable metal deposition system 220 may be controlled (e.g., by controller 253) to deposit material (e.g., first, second, third, fourth, etc. portions) layer by layer. OMIH 100 may be controlled by (e.g., by controller 253) to adjust controllable aspects of OMIH 100 as described hereinabove. Controllable aspects may include voltage, current, phase, tilt angle, gap, working distance of coils as described hereinabove. As such, the shape, temperature and position of heated region may be fixed or vary dynamically during heating and cooling cycles.

[00122] In the embodiment illustrated in Fig. 8, deposition unit 220 may be moved laterally across the surface of the metal in a linear or other pattern, while molten metal 204 is deposited. The motion may be in a direction parallel to the axis connecting the centers of the coils, in a perpendicular direction or in a rotational direction. OMIH system 100 that is part of deposition unit 220 or otherwise coupled to deposition module 206 (for example, carried by a common motion unit, not shown), may follow the movement of deposition unit 220. It will be appreciated that deposition unit 220 may make a plurality of passes per deposition layer in, for example, a discrete, a continuous or a scanning profile.

[00123] It will be appreciated that additive casting system 300 may deposit molten metal directly onto a preheated region without overheating, and may continue heating during the deposition. [00124] In operational scenarios involving cooling the working areas after molten metal deposition (“post-heating”), MIH system 110 may be used for post heating. Heating can be adjusted to control the cooling rate of the deposited material, thus affecting and controlling the crystalline structure into which it may form.

[00125] Movable dispensing unit 230 and movable metal deposition system 220 may be controlled (e.g., by controller 253) to deposit material (e.g., first, second, third, fourth, etc. portions) layer by layer. OMIH 100 may be controlled by (e.g., by controller 253) to adjust controllable aspects of OMIH 100 as described hereinabove.

Surface Heating and Ablation System

[00126] It will be appreciated that OMIH system 100 may operate as a workpiece heater for a metal surface heating and ablation system. Fig. 9, to which reference is now made, illustrates a surface heating and ablation system 400 that may incorporate OMIH system 100 as described hereinabove.

[00127] Surface heating and ablation system 400 comprises a movable surface heater system 420, a build table 416, and a controller 453.

[00128] System 400 may be configured to heat areas of a metallic substrate 401 positioned on build table 416, or to remove molten metal areas of, and thus, shaping or smoothing metallic substrate 401 as described herein below.

[00129] Surface heater unit 420 may move along a heater path HP, at a working distance Wd above metallic substrate 401 heating working areas 402. Working distance Wd may be dictated by the shape or profile of metallic substrate 401 , or some other factor. Heater unit 420 itself may move in any direction on path HP relative to build table 416, or build table 416 may move in any direction on table path TP relative to heater unit 420. Movement may be before, during or after a heating cycle and may be controlled by controller 453.

[00130] Surface heater unit 420 may comprise OMIH system 100, a temperature sensor module 404, a distance sensor module 405, a camera module 406, or other sensing, measuring or controlling modules (not shown). Modules 404, 405 and 406 may be used by controller 453 to sense and adjust any controllable aspects of OMIH system 100 accessible through gap region KR between open ends 104 of OMIH system 100 as described hereinabove. Controllable aspects may include voltage, current, phase, gap, gap geometry, working distance as described hereinabove. As such, the shape, temperature and position of heated region 402 may be fixed or vary dynamically during heating, cooling and ablation cycles.

[00131] For example, temperature sensor 404 may be used to adjust power settings to ensure substrate 401 becomes molten and ablation occurs. Distance sensor 405 may be used by controller 453 to control Wd, to create a uniform surface as measured from sensor 405. It will be appreciated that module functionality may not be limited to sensing and measuring, and that other types of application modules may be used for other applications. For example a laser module (not shown) may be used to add high rate deposition functionality as described in US Patent Publication US2016/0271732A1, dated September 22, 2016.

[00132] It will be appreciated that heated region 402 may have a static or a dynamic profile, as controlled by controller 453. Controller 453 may adjust controllable aspects of OMIH system 100, such as voltage, current, phase, tilt angle, gap, and working distance of coils as described hereinabove. As such, the shape, temperature and position of heated region 402 may be fixed or vary dynamically during heating, cooling and ablation cycles.

[00133] In the embodiment illustrated in Fig. 9, heater unit 420 may be moved laterally across the surface of the metal 401 (or any electrically conductive workpiece) in a linear or other heating path pattern. The motion may be in a direction parallel to the axis connecting the centers of the coils, in a perpendicular direction or rotational. OMIH system 100 may follow the movement of heater unit 420. It will be appreciated that heater unit 420 may make a plurality of passes in, for example, a discreet, a continuous or a scanning profile.

[00134] In operational scenarios involving controlled cooling of working area 402 after heating or ablation (“post-heating”), OMIH system 100 may be used for post heating. Heating may be adjusted to control the cooling rate, thus affecting and controlling the crystalline structure into which it may form.

[00135] For simplicity, Fig. 9 depicts a heater system movable over a stationary workpiece placed over a build table, but this is not necessarily so. A relative movement along a pre-defined heating path between the surface heater and the electrically conductive workpiece can be provided in various manners known in the art. The controller may be further configured to controlling a pace of the relative movement along a pre-defined heating path in response to readings of the one or more sensors.

Foil Container Sealing System (not shown)

[00136] It will be appreciated that OMIH system 100 may be used for other metallic substrate heating applications, such as foil container sealing. In this embodiment, a thin metallic foil substrate may be heated, to be used to seal the opening of a bottle or other container using a weld, hot glue or other sealing method known in the art. [00137] In this embodiment, build table 416 may be modified with, for example, a channel, to position containers in the gap, under heating system 420 and under metallic substrate 402. A cutting system may be in the gap of heating system 420 or another module, to cut the foil seals to a desired shape before, during or after sealing.

[00138] It will be appreciated that the coils used in such a system may not be energized with high currents and may use coils that are wire-wound, rather than shaped water cooled metallic tubes.

[00139] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

[00140] As used throughout the specification, the terms "metal" or "metallic" refers to any metals and/or mellitic alloys which are suitable for melting and casting, for example, ferrous alloys, aluminum alloys, copper alloys, nickel alloys, magnesium alloys, and the like.

[00141] Any reference in the specification to a method should be applied mutatis mutandis to a system capable of executing the method and should be applied mutatis mutandis to a non-transitory computer-readable medium that stores instructions that, once executed by a computer, result in the execution of the method. Any reference in the specification to a system should be applied mutatis mutandis to a method that may be executed by the system and should be applied mutatis mutandis to a non-transitory computer-readable medium that stores instructions that may be executed by the system. [00142] The terms "front," "back," "top," "bottom," "over," "under", and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the present disclosure described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

[00143] The subject matter regarded as the technique of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. The technique of the present disclosure, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the detailed description when read with the accompanying drawings.

[00144] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[00145] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word 'comprising' does not exclude the presence of other elements or operations and stages than those listed in a claim. Furthermore, the terms "a" or "an," as used herein, are defined as one or more than one. Also, the use of introductory phrases such as "at least one" and "one or more" in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The same holds true for the use of definite articles. Unless stated otherwise, terms such as "first" and "second" are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS What is claimed is:

1. An heating system for heating a working area of an electrically conductive metallic workpiece, the system comprising: an induction coil arrangement comprising at least one induction coil arranged with one or more turns defining at least one core to produce a magnetic field; a magnetic-flux-concentrator (OMFC) positioned, in part, within said at least one core and having a shape with two open ends and a gap region between the two open ends of said OMFC, to direct said magnetic field within said OMFC, and to direct said magnetic field crossing said gap region to graze said electrically conductive metallic workpiece below said gap region, to induce heating in a heated region in said electrically conductive metallic working area; and an AC (alternating current) current source to supply AC current to said at least one induction coil.

2. The heating system of claim 1 wherein the shape is an uncomplete ring or a horseshoe shape.

3. The heating system of claim 1 wherein said OMFC is oriented to form an unobstructed central region above said gap region, to allow line of sight access from above said heating system to said heated region.

4. The heating system according to claim 1 wherein said OMFC is shaped to form an unobstructed central region above said gap region, to allow line of sight access from above said heating system to said heated region.

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SUBSTITUTE SHEET (RULE 26)

5. The heating system of claim 1 wherein the induction coil arrangement is a single multi-tum solenoid wound around said OMFC.

6. The heating system of claim 1 wherein the induction coil arrangement comprises two coil rings each wound around said OMFC.

7. The heating system of claim 1, wherein the induction coil arrangement comprises multiple multi-turn coils, each of said multiple multi-tum coils defining a core.

8. The heating system of claim 1, wherein the induction coil arrangement comprises one or more multi-turn coil wound around said OMFC.

9. The heating system of claim 1 wherein the induction coil arrangement comprises a first coil arrangement with a first OMFC inducing heating at a first heated region and a second coil arrangement with a second OMFC inducing heating at a second heated region, wherein the second heated region is located adjacent to the first heated region.

10. The heating system of claim 9 wherein a relative polarity of magnetic flux flowing through the first OMFC and through the second OMFC is parallel or anti-parallel.

11. The heating system of claim 1 further comprising a cooling arrangement for cooling said induction arrangement.

12. The heating system of claim 11 wherein said cooling arrangement comprises a cooling jacket.

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SUBSTITUTE SHEET (RULE 26)

13. The heating system of claim 11 wherein the induction arrangement comprises one or more hollow coils and wherein said cooling arrangement is arranged to circulate a coolant through the one or more hollow coils.

14. The heating system of claim 1 wherein said AC current has an amperage of at least 1KA and a frequency of at least lOOKHz.

15. The heating system of claim 1 further comprising a current source controller configured to control and adjust one or more of: current amplitude, current phase, and current frequency.

16. The heating system according to any one of claims 1 to 15 wherein said heated region is not a footprint of either said OMFC or said at least one induction coil.

17. The heating system according to any one of claims 1 to 16 wherein a geometry of said heated region is a function of (1) a geometry of the coil arrangement, (2) a geometry of the gap region, (3) an orientation of said OMFC (4) a height of a bottom part of said OMFC above the electrically conductive metallic workpiece; and (5) a number of coil turns in said at least one coil arrangements.

18. A casting system for casting a metallic object by constructing a plurality of production layers forming a vertical stack, wherein the production layers have mold regions, wherein the production layers have object regions defined by the mold regions, and wherein a current production layer is constructed upon a top surface of a previous production layer of the vertical stack, the system comprising: a mold construction system operative to construct a mold region of the current production layer;

36

SUBSTITUTE SHEET (RULE 26) a metal deposition system operative to construct an object region of the current production layer; a build table for supporting the vertical stack of production layers; and a controller for controlling at least the mold construction system and the metal deposition system, wherein the metal deposition system comprises a heating system according to any of claims 1 to 17.

19. The casting system according to claim 18 wherein the metal deposition system is configured to deposit molten metal on the previous production layer through said gap of the heating system.

20. The casting system according to claim 18 wherein the controller is further configured to control the heating system so as to heat the previous production layer before molten metal deposition, during molten metal deposition or after molten metal deposition.

21. The casting system according to claim 18 further comprising a temperature sensor and/or a height sensor for measuring, through said gap region of the heating system, a temperature and/or a relative height of said working area, and wherein the controller is further configured to control the metal deposition system in response to readings of said temperature sensor and/or said height sensor.

22. A surface heating and ablation system for treating a surface of an electrically conductive workpiece, comprising a movable surface heater, at least one sensors, and a controller, the controller is configured to control one or more operational parameters of said surface heater in

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SUBSTITUTE SHEET (RULE 26) response to readings of said at least one sensor, wherein the surface heater is a heating system according to any of claims 1 to 17.

23. The surface heating and ablation system of claim 22 wherein said at least one sensor is a temperature sensor, a distance sensor or a camera.

24. The surface heating and ablation system of claim 22 wherein the one or more operational parameters of said surface heater are from among a group consisting of: a distance of the surface heater system from the electrically conductive metallic workpiece, voltage, current amperage, current phase, and current frequency.

25. The surface heating and ablation system of claim 22 further comprising a motion system for providing a relative movement along a pre-defined heating path between said surface heater and said electrically conductive workpiece, and wherein the controller is further configured to controlling a pace of said relative movement along a pre-defined heating path in response to readings of the one or more sensors.

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SUBSTITUTE SHEET (RULE 26)