Laminated metal casting system and method

Abstract

To provide a multilayer metal casting system and method that facilitates the application of inoculants and additives during multilayer metal fabrication, enabling mass production at low cost, with increased throughput, and high metallurgical quality and consistency. [Solution] A multilayer metal casting system is provided for casting a metal object by producing a stack of production layers having mold regions and object regions, wherein the mold regions constitute a mold in progress, and the object regions constitute a casting in progress retained within the mold in progress, and the system comprises a metal processing system in the casting in progress comprising: a surface melter for melting a first volume of previously solidified metal; a metal depositor for dropping a second volume of molten metal into the first volume; and a powder introduction unit for delivering an allocated amount of at least one casting property modification powder, wherein the first and second volumes accumulate in a molten zone of at least a minimum volume of molten material required for the casting property modification process.

Description

[Technical Field]

[0001] This disclosure relates to additive metal fabrication in general, and more specifically to additive metal casting employing molten metal deposition and the provision of inoculants and additives. [Background technology]

[0002] Inoculants and additives are two types of materials used in metal casting to modify the properties of the molten metal and improve the final quality of the casting.

[0003] Inoculants are materials primarily used in cast iron and added to molten metal to modify the size, shape, and distribution of graphite in the cast iron. After being added to the molten metal, the inoculant dissolves and reacts with the molten metal to modify the microstructure of the resulting casting. Inoculants are typically made from materials containing elements such as silicon, aluminum, barium, strontium, cerium, and others that react with the molten metal to provide nucleation sites for graphite formation. Inoculants are added to the molten metal immediately before or during injection. Proper graphite inoculation can improve the mechanical properties of castings, such as strength and toughness, and can also reduce the occurrence of defects such as shrinkage and porosity.

[0004] Additives are materials added to molten metal to alter its chemical composition or physical properties. Alloying elements such as manganese, chromium, and nickel are added to molten metal to improve its strength, corrosion resistance, or other specific properties.

[0005] In conventional casting, molten metal deposition involves completely removing the molten metal into the manufactured mold, preferably as quickly as possible and in a single burst. The molten metal flow is often designed to overcome flow obstructions associated with holes, windows, and additional metal casting features. Inoculants and additives are added to the molten metal before or during injection.

[0006] U.S. Patent No. 5,755,271 discloses a post-inoculation method in which an additive is placed in a passage of molten metal between an injection cap and a mold. U.S. Patent Application Publication No. 2005 / 0189083A1 discloses a mold and a method of using it to achieve in-mold modification of a cast metal. One or more chambers are located within the runner system of the mold. Each chamber may contain a metallurgical modifier to adjust the chemical composition of the metal and improve the mechanical and physical properties of an article cast from the metal. When the mold is assembled for use, one or more modifiers can be placed in the chambers. When the molten metal is introduced into the mold, the molten metal passes through the chambers and liquefies the modifiers.

[0007] Several articles discuss the challenges of metal additive manufacturing. Amit Bandyopadhyay, Kellen D.Traxel, Invited commentary paper: Metal-additive manufacturing-Modeling strategies for application-optimized designs, Additive Manufacturing, Volume 22, 2018, Pages 758-774, ISSN 2214-8604, David Svetlizky, Baolong Zheng, Tali Buta, Yizhang Zhou, Oz Golan, Uri Breiman, Rami Haj-Ali,Julie M.Schoenung,Enrique J.Lavernia,Noam Eliaz,Directed energy deposition of Al5xxx alloy using Laser Engineered Net Shaping(LENS(registered trademark)),Materials&Design,Volume192,2020,108763,ISSN0264-1275,Ahn,DG.Directed Energy Deposition(DED)Process:State of the Art.Int.J.of Precis.Eng.and Manuf.-Green Tech.8,703-742(2021), and Scott M.Thompson,Linkan Bian,Nima Shamsaei,Aref Yadollahi,An overview of Direct Laser Deposition for additive manufacturing;Part I:Transport phenomena, modeling and diagnostics,Additive Manufacturing,Volume8,2015,Pages36-62,ISSN2214-8604.

[0008] There is a need for a multilayer metal casting method and apparatus that facilitates the application of inoculants and additives during multilayer metal fabrication, enabling mass production at low cost, with increased throughput, and with high metallurgical quality and consistency. These objectives are met by embodiments of the present disclosure. [Overview of the project]

[0009] According to one aspect of the present disclosure, a multilayer metal casting system is provided for casting a metal object by producing a stack of production layers having mold regions and object regions, wherein the mold regions constitute a mold in progress, and the object regions constitute a casting in progress retained within the mold in progress, and the multilayer metal casting system comprises a metal processing system including a surface melter for melting a first volume of previously solidified metal in the casting in progress, a metal depositor for dropping a second volume of molten metal into the first volume, and a powder introduction unit for delivering an allocated amount of at least one casting property modification powder, wherein the first and second volumes accumulate in a molten zone of at least a minimum volume of molten material required for a casting property modification process.

[0010] In some embodiments, the powder introduction unit comprises a supply nozzle configured to output casting property modifying powder at a powder delivery angle and standoff distance relative to the molten zone, the molten zone having a molten zone boundary, and the powder delivery angle and standoff distance are pre-selected to ensure that the spot size of the delivered input amount of the accumulated amount on the molten zone is within the molten zone boundary. The powder nozzle may be configured to maintain a powder spot size in the range of 2 to 50 mm in diameter with a powder nozzle standoff distance of 12 to 150 mm and a delivery angle in the range of 15 to 75°.

[0011] In some embodiments, the powder introduction unit comprises a feeder (feeder unit) for feeding one or more feeding amounts of at least one casting property modification powder. The feeder may comprise a powder reservoir for containing the casting property modification powder, a feeding mechanism configured to release a predetermined amount of powder from the powder reservoir, an inspection volume for collecting the amount of powder released before delivery to the melting zone, and a delivery system. The feeding mechanism may be configured to provide powder feeding amounts ranging from 1 microgram to 10 grams per feeding amount. The delivery system may be a pressurized gas delivery system, and the feeder may further include a pressurized gas supply operably connected to the inspection volume for propelling the collected amount of powder toward the melting zone. The feeder may comprise a plurality of powder reservoirs, each containing a different casting property modification powder, and the feeding mechanism is configured to selectively release a predetermined amount from one or more of the powder reservoirs according to the desired casting properties.

[0012] In some embodiments, the system further comprises a controller operably connected to a molten metal depositor, a surface melter, and a powder introduction unit, the controller being configured to adjust the molten metal depositor, the surface melter, and the powder introduction unit to maintain a predetermined minimum volume of molten zone in a molten state for at least a minimum duration sufficient to cause a desired casting property modification process in the minimum volume of molten material allocated to it.

[0013] In some embodiments, the depositor deposits a first volume of molten metal by releasing droplets of molten metal in the form of (1) discrete droplets, (2) continuous dripping, or (3) continuous flow.

[0014] In some embodiments, the multilayer metal casting system further comprises at least one temperature sensor for sensing the temperature of at least the molten zone, the at least one temperature sensor communicating data with a controller, the controller further configured to adjust the melter, metal depositor, and powder introduction unit based on the temperature data received from the at least one temperature sensor.

[0015] The controller may further be configured to implement a continuous scanning mode in which the metalworking assembly moves continuously along the processing path while maintaining a dynamic melting zone, and a discrete scanning mode in which the metalworking assembly sequentially processes separate work areas, the controller selecting the scanning mode based on at least one of the part's geometry, thermal requirements, or material properties.

[0016] The controller may be further configured to adjust scanning parameters in response to real-time thermal feedback, maintain a minimum melt zone volume specific to each scanning mode, adjust the timing of powder introduction depending on the selected scanning mode, and manage thermal conditions at the boundaries between adjacent working areas.

[0017] In some embodiments, the controller is further operably connected to the mold builder, the controller is further configured to control the mold builder to build the mold in progress, and the controller is further configured to adjust the mold builder to build the current mold area of ​​the current production layer on the casting in progress before processing the current material area of ​​the current production layer.

[0018] In some embodiments, the multilayer metal casting system may further comprise an inert environment unit, in which at least a portion of the depositor, surface melter, and powder introduction unit adjacent to the molten zone and free-fall molten metal is maintained in an inert environment. In some embodiments, the depositor, surface melter, powder introduction unit, and inert environment unit are physically connected and arranged as a single processing assembly that is movable over the surface of the casting in progress.

[0019] In some embodiments, the depositor is rotatable around the feed axis of an integrated processing assembly and includes a metal rod capable of lifting the feed axis up and down; the surface melter includes an induction heating unit having a planar closed coil with an opening positioned concentrically with the feed axis; an inert environment unit is positioned around the induction heating unit; and a powder introduction unit has a feed nozzle positioned close to the depositor, through which molten metal and casting property modifying powder free-falling from the depositor are supplied to the melting zone.

[0020] In some embodiments, the laminated metal casting system further comprises a motion unit, and a controller is further configured to control the motion unit to provide relative movement of at least the depositor, surface melter, and powder introduction unit across the upper surface of the casting in progress.

[0021] In some embodiments, the surface melter is further configured to supply heat to the molten zone after a first volume and a second volume have been accumulated, thereby influencing the cooling rate of the molten zone from the melting temperature. In some embodiments, the surface melter is further configured to supply heat to the molten zone after a first volume and a second volume have been accumulated, thereby maintaining the molten zone in a molten state for a predetermined duration.

[0022] In some embodiments, for each production layer, the second volume of free-falling molten metal corresponds to the height of the current object region and the geometric shape of the inner wall of the mold region. The first volume for remelting can be calculated based on a predetermined cross-sectional area defined by a predetermined height of the casting in progress and the geometric shape of the inner wall of the mold in progress corresponding to the predetermined height of the casting in progress. The predetermined height of the casting in progress for remelting may be in the range of 0.5 mm to 200 mm. The predetermined height of the casting in progress may be equal to one of the group consisting of (1) half the height of the object region, (2) the height of the object region, (3) twice the height of the object region, (4) three times the height of the object region, and (5) four times the height of the object region.

[0023] In some embodiments, the controller is configured to (1) determine a relative movement path of the depositor and the surface melter across the upper surface of the ongoing casting, thereby setting a deposition plan for the first volume and the second volume, and (2) determine one or more powder introduction sites along the movement path, such that when a metallurgical modification powder is delivered to one of the powder introduction sites, at least a minimum volume is accumulated in each melting zone. The height of the current object region may be in the range of 2 mm to 50 mm.

[0024] In some embodiments, the controller is further configured to affect the cooling rate of a predetermined minimum volume when cooling from its melting temperature by setting one or more of (1) the first volume, (2) the second volume, (3) the deposition rate of the depositor, and (4) the melting rate of the melter.

[0025] According to one aspect of the present disclosure, a laminated metal casting system for casting a metal object by producing a stack of production layers having a mold region and an object region, wherein the mold region constitutes the ongoing mold, the object region constitutes the ongoing casting retained within the ongoing mold, and the laminated metal casting system includes, in the ongoing casting, a surface melter for melting a first volume of previously solidified metal, and a metal depositor for dropping a second volume of molten metal into the first volume, wherein the first volume and the second volume accumulate within a melting zone of at least a minimum volume of molten material, a powder introduction unit for delivering an assigned amount of at least one casting property modifying powder, and an inert environment unit, wherein the depositor, the surface melter, the powder introduction unit, and the inert environment unit are physically connected and arranged as an integrated processing assembly movable across the upper surface of the ongoing casting, the depositor is rotatable about a supply axis of the integrated processing assembly and includes a metal rod capable of lifting the supply axis vertically, the surface melter includes an induction heating unit having a planar closed-loop coil with an aperture positioned concentrically with the supply axis, the inert environment unit is arranged around the induction heating unit, the powder introduction unit has an off-axis supply nozzle placed in proximity to the depositor, and the molten metal and the casting property modifying powder falling freely from the depositor are provided to the melting zone through the aperture, and a controller operatively connected to the molten metal depositor, the surface melter, and the powder introduction unit, configured to adjust the molten metal depositor, the surface melter, and the powder introduction unit to maintain the minimum volume of the melting zone in a molten state for at least a minimum duration sufficient for the assigned amount to cause a desired casting property modification process in the minimum volume of the molten material, a laminated metal casting system for casting a metal object is provided.

[0026] According to one aspect of the present disclosure, a multilayer metal casting method is provided for producing a metallic object by generating a stack of production layers having mold regions and object regions, wherein the mold regions constitute a mold in progress, and the object regions constitute a casting in progress retained within the mold in progress, and the method comprises, for each production layer, iteratively constructing a mold region of the current production layer on top of a stack of production layers, and processing the object region of the current production layer, wherein processing the object region of the current production layer comprises, in the casting in progress, melting a first volume of previously solidified metal, dropping a second volume of molten metal into the first volume, providing an allocated amount of at least one casting property modification powder into the molten zone, optionally maintaining the molten zone in a molten state for a predetermined minimum duration, and maintaining the molten zone in an inert environment while it is in a molten state, wherein the first and second volumes are accumulated in the molten zone in a minimum volume of molten material required for the casting property modification process.

[0027] In some embodiments, the casting property modification powder includes chemical modification materials and / or metallurgical modification materials.

[0028] In some embodiments, the casting property modification process includes at least one of the following: (1) controlled graphite nucleation and growth to achieve a predetermined graphite morphology and / or distribution; (2) controlled phase transformation to result in a predetermined phase ratio; (3) in-situ chemical composition modification to achieve a predetermined local material property; (4) grain refinement to result in enhanced mechanical properties; (5) precipitation hardening; or (6) a controlled solidification process to result in a predetermined dendrite arm spacing.

[0029] In some embodiments, the casting property modification process is controlled by one or more of the following: (1) maintaining a minimum volume at a predetermined temperature within a specific range for a predetermined residence time, or (2) maintaining a predetermined temperature gradient across the minimum volume.

[0030] In some embodiments, the molten metal is a cast iron alloy, and at least one powder material is selected from (1) grain refiners consisting of titanium alloys, zirconium alloys, and niobium alloys, and / or (2) inoculants consisting of ferrosilicon, aluminum, silicone carbide, calcium, strontium, cerium, sodium, barium, and rare earth elements, and / or (3) deoxidizers consisting of aluminum, silicon, manganese, and calcium, and / or (4) microstructure modifiers consisting of magnesium, cerium, lanthanum, and yttrium, and / or (5) carbide-forming agents consisting of vanadium, titanium, tellurium, tungsten, and molybdenum.

[0031] In some embodiments, the molten metal is steel and / or a steel alloy, and at least one powder material is selected from (1) grain refiners consisting of aluminum alloys, titanium alloys, zirconium alloys, and niobium alloys, and / or (2) oxygen scavengers consisting of aluminum, silicon, manganese, and calcium, and / or (3) microstructure modifiers consisting of magnesium, cerium, lanthanum, and yttrium, and / or (4) carbide-forming agents consisting of vanadium, titanium, tungsten, molybdenum, and niobium, and / or (5) corrosion-resistant modifiers consisting of chromium, nickel, molybdenum, silicon, aluminum, titanium, niobium, and phosphorus.

[0032] In some embodiments, the allocated amount of casting property modification material is adjusted based on a predetermined fading rate of the casting property modification powder during remelting.

[0033] In some embodiments employing an iron alloy, the minimum volume is at least 2 cubic centimeters.

[0034] In some embodiments employing an iron alloy, the minimum volume has a cooling rate of 2°C / second (or 100k / second) or less when cooled from its melting temperature.

[0035] In some embodiments, a predetermined minimum duration is sufficient for the allocated amount to induce the desired casting property modification process in a minimum volume of molten material. In some embodiments, a predetermined minimum duration is sufficient to allow complete melting and homogenization of the allocated amount of casting property modification material in the molten zone. In some embodiments employing an iron alloy, the predetermined minimum duration is at least 1 second.

[0036] In some embodiments, during the drop-out process, the molten metal droplets and the molten zone are maintained within a predetermined temperature difference not exceeding 100°C.

[0037] In yet another aspect of the present disclosure, a method for producing a final casting by a metalworking assembly, in which an allocated amount of at least one casting property modification powder is allocated to a molten zone in a casting in progress, wherein the production layer has a mold area and a body area, the mold area constitutes a mold in progress, the body area constitutes a casting in progress held within the mold in progress, and the molten zone consists of a first volume of molten, previously solidified metal and a second volume of newly added molten metal in the casting in progress, and the method is based on at least the following data items, A method is provided which includes determining the amount of powder allocated to the production layer, and determining the number and location of powder introduction points and the allocation of powder to specific molten zones generated in the current production layer by optimizing the synchronization of: (1) the target properties desired in the final casting and at least one casting property modifying powder to be used, (2) the volume of the object area, (3) the volume of previously solidified metal to be remelted, and (4) the operating parameters of the metal processing assembly, and the following: (1) molten zone accumulation time, (2) powder introduction delay time; and (3) optionally, maintaining the values ​​of the operating parameters of the metal processing assembly within an acceptable range.

[0038] The data items for at least one casting property modification powder used may include the fading characteristics of at least one casting property modification powder under reheating and remelting. The data items for the operating parameters of the metalworking assembly may include data relating to at least the processing path, metalworking assembly speed, metal deposition rate, and melter current supply parameters. The operating parameters of the metalworking assembly may include at least the speed of the metalworking assembly, the working distance of the metalworking assembly over the current production layer, metal deposition rate, surface heater current supply, and source heater current supply. [Brief explanation of the drawing]

[0039] The subject matter considered to be the present invention is specifically pointed out and explicitly claimed in the concluding section of this specification. However, the present invention, with respect to both its organization and method of operation, along with its object, features, and advantages, can be best understood by referring to the following detailed description when read together with the accompanying drawings.

[0040] [Figure 1a] Figure 1a is a schematic diagram illustrating a metal processing system and its operation according to embodiments of the present disclosure in two production scenarios. [Figure 1b] Figure 1b is a schematic diagram illustrating a metal processing system and its operation according to embodiments of the present disclosure in two production scenarios. [Figure 1c] Figure 1c is a system-level block diagram showing the functional components of an additive casting system according to an embodiment of the present disclosure, incorporating the metal processing systems shown in Figures 1a and 1b. [Figure 1d] Figure 1d is a schematic diagram showing a metalworking assembly that can be used in conjunction with the multilayer metal casting shown in Figure 1c. [Figure 1e] Figure 1e is a detailed view of the bottom of the metal processing assembly shown in Figure 1d, illustrating the powder introduction unit. [Figure 1f] Figure 1f is a detailed bottom view of another embodiment of a metal processing assembly incorporating a dual powder supply configuration. [Figure 1g]Figure 1g is a flowchart illustrating a method of multilayer metal casting according to an embodiment of the present disclosure. [Figure 2a] Figure 2a is a schematic diagram showing the components of a powder introduction system according to an embodiment of the present disclosure. [Figure 2b] Figure 2b is a flowchart illustrating a method for assigning casting property modification powder according to an embodiment of the present disclosure. [Figure 3a] Figure 3a shows microscopic images and data plots illustrating the experimental results of adding an inoculant to cast iron in Experiment 1. [Figure 3b] Figure 3b shows microscopic images and data plots illustrating the experimental results of adding an inoculant to cast iron in Experiment 1. [Figure 4a] Figure 4a shows the results of Experiment 2, including a microscopic image, chemical analysis results, hardness measurement values, and tensile test data, illustrating the experimental results of copper alloy addition to cast iron. [Figure 4b] Figure 4b shows the results of the experiment in Experiment 2 involving the addition of copper alloy to cast iron, including microscopic images, chemical analysis results, hardness measurements, and tensile test data. [Figure 4c] Figure 4c shows the results of Experiment 2, including a microscopic image, chemical analysis results, hardness measurement values, and tensile test data, illustrating the experimental results of copper alloy addition to cast iron. [Figure 4d] Figure 4d shows the results of Experiment 2, including a microscopic image, chemical analysis results, hardness measurement values, and tensile test data, illustrating the experimental results of copper alloy addition to cast iron. [Figure 4e] Figure 4e shows the results of Experiment 2, including a microscopic image, chemical analysis results, hardness measurement values, and tensile test data, illustrating the experimental results of copper alloy addition to cast iron. [Figure 4f] Figure 4f shows the results of the experiment in Experiment 2 involving the addition of copper alloy to cast iron, including microscopic images, chemical analysis results, hardness measurements, and tensile test data. [Figure 4g] Figure 4g shows the results of the experiment in Experiment 2 involving the addition of copper alloy to cast iron, including microscopic images, chemical analysis results, hardness measurements, and tensile test data. [Figure 4h]Figure 4h shows the results of the experiment in Experiment 2 involving the addition of copper alloy to cast iron, including microscopic images, chemical analysis results, hardness measurements, and tensile test data. [Figure 5a] Figure 5a shows microscopic images and graphic data illustrating the experimental results of magnesium treatment of ductile iron in Experiment 3. [Figure 5b] Figure 5b shows microscopic images and graphic data illustrating the experimental results of magnesium treatment of ductile iron in Experiment 3.

[0041] For the sake of brevity and clarity in the illustrations, it should be understood that the elements shown in the figures are not necessarily shown to scale. For example, some dimensions of elements may be exaggerated relative to others for clarity. Furthermore, where deemed appropriate, reference numbers may be repeated between drawings to indicate corresponding or similar elements. [Modes for carrying out the invention]

[0042] Additives in metal additive manufacturing While the use of inoculants and additives in conventional metal casting is well known, the addition of inoculants and additives in metal additive manufacturing presents significant technical challenges that affect process stability, product quality, and manufacturing efficiency.

[0043] The fundamental technical challenge concerns the timing and distribution control of additives and inoculants within the molten metal during the additive manufacturing process. Unlike conventional casting methods, additive manufacturing typically involves a small molten pool and a substantially rapid solidification rate, thereby providing limited time for proper chemical and metallurgical processes. This time constraint can lead to a non-uniform distribution of introduced materials, resulting in inconsistent material properties in the fabricated components.

[0044] Temperature control presents another significant technical hurdle. The rapid heating and cooling cycles characteristic of additive manufacturing (e.g., DED) can substantially affect the melting rate of the introduced material, thus requiring precise control within a narrow processing window. Temperature gradients within the molten pool can lead to premature solidification or undesirable reactions, particularly at high temperatures where thermal decomposition of sensitive additives can occur.

[0045] Process-specific technical challenges vary depending on the additive manufacturing method employed. Powder bed systems present limitations in achieving on-site material addition, while pre-mixing with powder raw materials introduces complexities related to powder handling, separation, and fluidity. Directed energy deposition (DED) systems face distinct challenges, including feed rate synchronization, management of multiple powder feeds, potential nozzle clogging, and complex powder flow interactions.

[0046] Processing of iron and iron alloys in additive manufacturing Iron (and steel) is commonly used in many industrial applications due to its high strength and durability. However, iron and iron alloys are more difficult to process in additive manufacturing (compared to, for example, aluminum). Processing iron and iron alloys in additive manufacturing (AM) presents distinct metallurgical challenges, mainly caused by rapid solidification and the complex phase transformations and microstructure evolution during subsequent thermal cycling. During cooling, iron undergoes multiple solid phase transformations. These transformations are highly sensitive to the cooling rate and thermal gradient. The resulting transformation products are susceptible to damage from the formation of non-equilibrium phases, exhibiting diverse particle morphologies and complex transformation products, and may be prone to residual stress generation and potential cracking.

[0047] The handling of iron and iron alloys in additive manufacturing technologies such as laser powder bed fusion (L-PBF), electron beam powder bed fusion (EB-PBF), and directed energy deposition (DED) remains unresolved on an industrial scale, and AM iron and iron alloy products are prone to distortion, strain, cracking, or porosity during the additive manufacturing process. Because iron is brittle, it cannot be processed into a wire form suitable for wire arc additive manufacturing (WAAM). The molten pool width produced in DED technology is typically about 0.5–2 mm and the depth is 0.2–0.8 mm. The volume of the molten pool is about 0.1–0.5 cubic millimeters (0.0001–0.0005 cc). The cooling rate of the molten pool in DED is typically very rapid, 10³–10⁵ K / sec, and the solidification time of the molten pool is on the order of milliseconds to microseconds. Therefore, there is limited time for metallurgical transitions and homogenization. The rapid solidification process of the added molten metal in DED significantly limits the feasibility of complete dissolution of the additive, proper nucleation and growth of the desired microstructure, and uniform distribution of alloying elements and control of phase transformation. Furthermore, the powder capture efficiency in DED is in the range of 20% to 30%.

[0048] Voxel casting, particularly voxel casting of iron and iron alloys using casting property modifiers. This disclosure focuses on the layered casting of voxels of molten metal, particularly the layered casting of voxels of iron and iron alloys. Embodiments of this disclosure are illustrated with respect to gray cast iron and ductile iron.

[0049] The applicant has found that additive treatment of metal voxels having a minimum volume for individual processing (voxelized additive manufacturing) can result in castings having metallic properties characteristic of conventional castings. For illustrative purposes, embodiments of the present disclosure facilitate the treatment of molten metal voxels in the range of 2 to 100 cc each with additives and / or inoculants. Molten metal voxels exceeding the minimum volume can be treated individually, resulting in cooling profiles ranging from 1, 2, or more seconds to several minutes. Such cooling profiles are longer compared to, for example, the cooling profiles of other additive manufacturing techniques (e.g., DED, SLM), and therefore facilitate metallurgical and chemical processes.

[0050] The applicant found that the additive treatment of voxels of molten metal requires (1) remelting of previously solidified metal, and (2) a combined treatment of the volume of newly added molten metal and the volume of remelted, previously solidified metal. Therefore, the minimum volume that facilitates the metallurgical and chemical processes is due to the volume of newly added molten metal and the remelting of previously solidified metal.

[0051] A minimum volume of approximately 2 cubic centimeters represents a critical threshold linked to mold area containment. The mold area provides the necessary mechanical and thermal boundary conditions for handling these volumes, while the volume itself provides the thermal mass required for proper metallurgical control. Without mold containment, it would be impossible to handle such volumes of molten metal in a geometrically stable manner. Without sufficient volume, even with mold containment, it would be impossible to properly control or achieve a proper metallurgical process.

[0052] According to one aspect of the present disclosure, a multilayer metal casting system and method are provided for enabling the localized, controlled, and iterative application of inoculants, additives, and other casting property modifiers to voxels of molten metal during the multilayer casting of metal (metallic) parts.

[0053] According to one aspect of the present disclosure, a metal processing system is provided that facilitates the controlled supply of casting property modification powder to molten metal as part of a multilayer casting process. The metal processing system processes metal voxels present in the mold region (cavity) in synchronization with a mold construction system.

[0054] Another aspect of the present disclosure provides a metallizing system that enables, as needed, control of the mechanical and / or chemical and / or physical and / or metallurgical properties of a casting to ensure an optimal process in terms of both quality (metallurgical and geometric) and throughput. Another aspect of the present disclosure provides a metallizing method for layered casting that incorporates operating a metallizing system that enables control of the mechanical and / or chemical and / or physical and / or metallurgical properties of a casting.

[0055] The voxelized layered casting systems and methods described herein are based on two interconnected fundamental principles that enable the successful processing of iron alloys. First, processing of the metal within a limited mold area, which allows for the controlled melting and processing of a considerable volume of molten metal while maintaining geometric stability. Second, processing of a considerable volume of molten metal (2 cc or more) allows for proper metallurgical control and modification of the casting properties through controlled thermal conditions and appropriate processing time. These principles work in conjunction, with the mold area enabling the processing of larger volumes by providing containment and thermal control, while the larger volumes enable proper metallurgical processes by providing sufficient thermal mass and processing time.

[0056] Figure 1a is a block diagram of the functional units and functional processing structure of a metal processing system 100 for molten metal additive casting according to one embodiment of the present invention.

[0057] The metal processing system 100 comprises at least a metal depositor 102, a surface melter 104, and a powder introduction system 106. An example of production scenario 10 is shown in Figure 1a, and the production layer PL produced by the metal processing 100. i The production process is illustrated. Mold layeri After it is constructed, the metal layer i Production layer PL during production i The intermediate production stage is shown. Metal layer i The material is produced on top of the in-progress casting 14. The in-progress casting 14 is positioned within the in-progress mold 16 on a forming table (not shown). The in-progress mold 16 is intended to shape the in-progress casting 14 and create a boundary for the molten zone 22 from sliding down.

[0058] During the operation, while the metal layer is being processed, elements 102, 104, and 106 are physically positioned in close proximity to the upper surface of the casting 14 in progress. A voxel of molten metal (molten zone 22) is produced by remelting previously solidified metal, indicated as a first volume 180, and adding new molten metal, indicated as a second volume 20. The volume of molten metal in the molten zone MZ accumulates as a portion of the casting 14 in progress is remelted (first volume) and new molten metal is added (second volume). In the intermediate production stage illustrated in Figure 1a, approximately half of the second volume has already been provided.

[0059] The metal depositor 102 comprises a source melting heater (multiple times) (not shown in Figure 1a) and an input metal source (not shown in Figure 1a), and is arranged to drop molten metal (e.g., free-fall discrete molten metal droplets, a continuous flow of molten metal droplets, or a stream of molten metal). Several free-fall molten metal droplets MD are shown in Figure 1a. The newly added molten metal MD constitutes a second volume. The metal depositor 102 may provide molten metal to the surface of the progressing casting 14 at a single deposit location, at several deposit locations, or while continuously scanning the surface of the progressing casting 14.

[0060] The surface melter 104 comprises a heater (e.g., an induction heater) arranged to heat and melt a previously solidified portion of the ongoing casting 14 before, during, and / or after the addition of molten metal MD. For example, the surface melter 104 is arranged as a planar coil existing on the upper surface of the ongoing casting 14. After the first volume and the second volume are accumulated within the complete melting zone, the melting zone can be maintained in a molten state for a predetermined duration.

[0061] The powder introduction system 106 is arranged to provide an allocated amount of the casting property modification powder into the melting zone MZ. The supply of the allocated amount of the casting property modification powder may be realized as a single dosage provided at a single supply site, or as multiple dosages provided at a single supply site or multiple supply sites. For example, the provision of a single dosage of the casting property modification powder from three series is illustrated.

[0062] FIG. 1b illustrates another example of the production scenario 12 implemented by the metal processing system 100 shown in FIG. 1a. During operation, during the processing of the metal layer, the elements 102, 104, and 106 are positioned physically close to the upper surface of the ongoing casting 14 and move thereon along the processing path PP (scanning). During the movement, a series of voxels MV are generated, each remelting a first volume V1 of the previously solidified metal st j and adding a second volume V2 of new molten metal MD nd j resulting from this. The powder input amount PD is provided to the molten metal voxel MVj.

[0063] In each production scenario, the allocated amount of the casting property modification powder corresponds to the volume of the melting zone resulting from the first volume and the second volume. The applicant has found that the volume of the melting zone must be at least a minimum volume.

[0064] The determination of the minimum volume in layered casting is fundamentally driven by the metallurgical requirements of the solidification and transformation processes of the iron alloy. For example, a minimum volume of approximately 2 cubic centimeters for gray cast iron represents a critical threshold at which a suitable metallurgical process cannot be adequately controlled or achieved. This threshold is governed by several interconnected metallurgical phenomena, as follows:

[0065] (1) Thermal mass requirements: A sufficient volume of molten metal is essential to maintain the thermal conditions necessary for controlled solidification and transformation. Smaller volumes (0.0001-0.0005 cc), such as those seen in DED processes, experience extremely rapid heat dissipation, which hinders (i) nucleation and growth of the graphite phase, (ii) formation and morphology of pearlite, and (iii) proper control of the distribution and dissolution of inoculants and additives.

[0066] (2) Control of solidification time: The voxel volume directly affects the solidification time due to its thermal mass. A minimum volume of 2 cc of iron alloy provides (i) a cooling rate that starts slowly on the order of 1°C / second, allowing sufficient time for carbon diffusion and graphite formation; (ii) a processing window that starts on the order of a few seconds, 1 to 10 seconds, preferably 2 to 5 seconds, which is essential for the complete dissolution of the inoculant; and (iii) a controlled temperature gradient that prevents premature freezing and allows for proper phase transformation.

[0067] (3) Chemical homogenization: Proper dissolution and distribution of inoculants and additives requires (i) a sufficient volume of liquid metal for complete dissolution, (ii) sufficient time for chemical homogenization by both diffusion and convection, and (iii) thermal conditions to prevent premature precipitation or separation.

[0068] (4) Control of graphite morphology: In the case of cast iron, the formation of the desired graphite morphology (whether flake, nodule, or compressed) requires (i) stable thermal conditions during nucleation and growth, (ii) sufficient time for carbon diffusion and graphite deposition, and (iii) an appropriate volume for unimpeded growth of the graphite structure.

[0069] (5) Development of microstructure: The achievement of the desired matrix structure (pearlite, ferrite, or mixed) depends on (i) controlled cooling by the eutectoid transformation temperature, (ii) sufficient time for the formation and growth of pearlite colonies, and (iii) a volume-dependent thermal gradient that affects the transformation kinetics.

[0070] These metallurgical requirements establish a lower limit of approximately 2 cc for voxel volume. Volumes below this 2 cc threshold can result in excessive cooling rates that hinder proper phase transformation, insufficient time for complete dissolution of additives, poor control of graphite morphology and distribution, inconsistent matrix microstructure, and poor mechanical properties.

[0071] The 100cc upper limit, in some embodiments, represents an upper volume that can be effectively and practically controlled while ensuring a desired fabrication throughput for a particular application, while maintaining (i) a uniform temperature distribution across the entire molten zone, (ii) a consistent cooling rate across the entire volume, (iii) a uniform distribution of additives and inoculants, and (iv) predictable and reproducible microstructure development. Embodiments of the present disclosure are not limited to the 100cc upper limit, and higher metal volumes can be processed in a voxelized manner.

[0072] According to embodiments of the present disclosure, the critical voxel volume is accumulated by (1) remelting metal present in a previously cast production layer and (2) depositing new molten metal.

[0073] Figure 1b shows the next voxel to be processed, MV j+1 Further examples are given. Figure 1b shows the first volume V1 melted by the surface melter 104. st j+1 (causes) new molten metal is added (V2 nd j+1 ), showing a working area WAj+1, which is part of the upper surface of the casting 14 in progress, thereby generating molten metal voxels MVj+1.

[0074] The term "voxelized" is used herein to indicate the ability of the additive casting embodiments presented in this disclosure to process specific voxels of molten metal. Voxelized metal processing can be achieved by processing the casting in progress (previously solidified metal and newly added metal) within the mold cavity (the mold in progress).

[0075] A particular voxel being processed is located in a specific portion of a particular production layer ("work area"). Processing a particular work area creates a molten zone by heating and melting the metal previously produced in the work area. The molten zone may further contain newly added molten metal, for example, dripped into the molten zone created in the work area by a melter. The volume of molten metal present in the molten zone of a particular work area is indicated as a "molten metal voxel" or "voxel".

[0076] The term “work area” is used herein to refer to a specific portion of the upper surface of the production layer currently being processed under a metalworking system. In the case of a small production layer, or a production layer having an object area with the same geometric dimensions of length and width as the surface heater of the metalworking system, the entire production layer may constitute a single “work area.” In the case of a large production layer, for example, a production layer having an object area with greater length and width than the geometric dimensions of the surface heater of the metalworking system, processing of the entire production layer involves processing of multiple work areas within that production layer.

[0077] In some embodiments of the present disclosure, processing of multiple work areas within a production layer involves moving across the production layer in a continuous scanning pattern or a discrete scanning pattern.

[0078] In a continuous scanning pattern, the working area includes a dynamically moving area that follows the movement of the processing assembly and, in the case of induction-based melting, the melter footprint. This dynamically moving working area is characterized by the dimensions and operating parameters used for process planning and process control. For example, the dimensions of the heating area, processing depth (combining layer height and remelting depth), heating time, melter footprint (heating area in progress), and deposition period. The continuous scanning pattern features the gradual movement of the melting zone with continuous overlap between adjacent working areas, facilitating continuous metal deposition and continuous or discrete powder delivery. This pattern can operate with constant or varying movement speeds, continuous heat input, and synchronized powder delivery.

[0079] The discrete scanning pattern utilizes separate static work areas where processing takes place, with clear boundaries between adjacent work areas. The dimensions of these discrete work areas are primarily determined by the fixed geometric shape and processing depth of the surface heater. In this pattern, complete processing of one area is performed before moving to the next area, and separate start / stop operations are involved. The discrete pattern allows for individual parameter control and separate process optimization for each work area, operating by residence times defined for each location and discrete powder delivery event.

[0080] Embodiments of the present disclosure are further illustrated by reference to continuous scanning patterns and discrete powder introduction patterns of a metal processing system (molten metal depositor, surface melter, and powder introduction unit).

[0081] The term "molten zone" is used herein to describe the change in the work area under the influence of a molten unit depositor, a surface heater, and a powder introduction unit, with the aim of generating a molten zone of at least a minimum volume. The volume of the molten zone within the work area grows to a desired critical minimum volume MV (voxels) under the combined influence of the molten unit depositor and the surface heater, and as a result, the powder introduction unit delivers powder to the voxels. In other words, the critical minimum volume MV (voxels) of the molten metal is used in process planning, while the molten zone volume is a measure that changes dynamically during processing. The development of the molten zone can be sensed, monitored, and controlled in real time. In a particular application, a molten zone of 2 cc of gray iron develops by melting and dripping in 1 to 10 seconds.

[0082] The production scenarios illustrated in Figures 1a and 1b are carried out under inert environmental conditions facilitated by an inert environment unit (not shown in Figure 1a).

[0083] Figure 1c is a schematic diagram of a multilayer casting system 110 according to one embodiment of the present disclosure. The multilayer casting system 110 is arranged in a dual production assembly configuration of a metalworking assembly 112 (for example, a metalworking system 100 considered with reference to Figures 1a-1b) and a mold production assembly 126. Each production assembly is assigned a dedicated XYZR motion system 134, for example, a large 6-axis articulated robotic arm or a gantry system capable of handling heavy objects. Embodiments of the present disclosure are not limited by the type of motion system used.

[0084] Not shown in Figure 1c are the molding table on which the production layer stack is produced, optional production chambers, optional production chamber heaters and coolers, optional molding table heaters, and supply and support systems such as power supplies, metal supplies, mold material supplies, gas supplies, powder supplies, and electronic equipment.

[0085] A system controller 136 is also shown in Figure 1c. The system controller 136 may be implemented digitally or via one or more analog control systems. The system controller 136 may include a processor with executable modules for controlling assemblies 112, 126, and units 114, 116, 118, 120, 122, 124, 128, 130, 132, and 134. The executable modules cover surface heating 138, surface melting 140, metal deposition 142, powder introduction 144, motion 146, inert environment 148, mold construction 152, and surface and wall finishing 154. The executable code includes algorithms and routines necessary to perform specific actions outlined by a specific molding plan of the laminated metal casting according to the present invention.

[0086] The system controller 136 also receives sensor and feedback data from various sensors and detectors 122. Sensors 122 may include sensors for temperature, flow rate, position, velocity, pressure, cumulative mass, and material composition. Sensors 122 may include other sensors such as infrared (IR) cameras, visible wavelength cameras, weight sensors (e.g., source weight sensors and / or molding table weight sensors), stereoscopic sensors (e.g., for measuring layer thickness), and distance sensors. The system controller 136 may also receive operator inputs (not shown) to precisely set and control the laminated metal casting process according to the present invention. The system controller 136 relies on a molding plan (not shown in Figure 1c) for data, details, and parameters that control the laminated casting operation.

[0087] The system controller 136 controls and coordinates the operation of the metalworking assembly 112 and the mold construction assembly 126 to produce a stack of production layers, each having mold regions and object regions. In each production layer, the mold construction assembly 126 manufactures the mold regions, thereby defining the shape and boundaries of each object region. Once the mold regions of a particular production layer are prepared, the metalworking assembly 112 manufactures the respective object regions. The mold regions of consecutive production layers constitute the ongoing mold 16, and the object regions of consecutive production layers constitute the ongoing casting 14 held within the ongoing mold 16. The main operations of mold region manufacturing and object region processing are interchangeable and performed under different thermal and environmental conditions.

[0088] The mold 16 in progress is configured to withstand the expansion and contraction forces exerted by the casting 14 in progress during the metalworking process.

[0089] It should be understood that the construction and operation of the mold construction assembly 126 do not form part of this disclosure and are therefore not described in detail herein, except that the production of the mold area may be carried out on-site or off-site. In various on-site embodiments, the mold production assembly 126 comprises a mold builder 128. The mold builder 128 may comprise a mold material reservoir and a mold depositor (not shown in Figure 1c), or may be fluidly connected to the mold material reservoir and mold depositor. In other embodiments, the mold production assembly 126 receives mold material from remote storage. In off-site embodiments, the mold production assembly 126 receives manufactured mold areas and / or mold frames, each assigned a number of production layers, from a remote source. The mold material may include mold material in paste form, powder form, granular form, slurry form, and mold material mixed with binders, release agents, activators, UV-absorbing particles, crosslinking agents, heat-absorbing particles, or other additives to facilitate the manufacture and use of the mold. According to embodiments of the present disclosure, the mold material includes, but is not limited to, ceramics (e.g., zirconia, alumina, magnesia, etc.), sand, clay, metal powders, and any combination thereof.

[0090] In some embodiments, the mold production assembly 126 further comprises a mold surface and wall finishing and treatment unit 130, which includes, but is not limited to, drying, hardening, milling, grinding, and polishing components for finishing the inner walls of the mold area (cavity) before metal deposition, or for semi-hardening or hardening the mold area before metal deposition.

[0091] In some embodiments, the mold surface treatment unit 130 can, for example, treat the upper surface of the mold area of ​​the current production layer before constructing the mold area of ​​a successive production layer.

[0092] PCT Patent Publications WO2023 / 275857 (filed April 14, 2022), WO2023 / 166506 (filed March 1, 2023), WO2024 / 100644, and WO2024 / 100642 (filed November 9, 2022) disclose additional information relating to the production of mold areas, and these are incorporated herein by reference.

[0093] Inert environmental conditions for metal processing can be achieved, for example, by a global inert environment unit 132 configured to promote inert conditions within the production chamber, a mobile inert environment unit 118 housed within the metal processing assembly 112 and configured to promote inert conditions, for example, adjacent to the melting zone, or a combination thereof.

[0094] In various embodiments, the surface melter 104 comprises one or more induction heaters, plasma heaters, electric resistance heaters, and torch heaters. Embodiments of the present disclosure will be further described with reference to surface melters including induction heaters.

[0095] In various embodiments, the molten metal depositor 102 includes a crucible, a remote molten metal reservoir, a wire or rod stock for melting, a powder for melting, or a combination thereof.

[0096] Embodiments of this disclosure will be described with reference to input metal in the form of a metal rod, for example, a certified gray cast iron rod. Using a metal rod, in particular a certified gray cast iron rod, as a raw material for layered casting offers significant technical advantages over powder-based approaches. The use of a metal rod ensures complete metallurgical integrity, as the deposited material maintains the exact composition and properties of the raw material, and the molten material is deposited, without any intermediate processing steps that could affect the material properties. This approach leverages established foundry-certified raw materials and provides complete traceability, verified material properties, and reliable chemical composition that meet industry standards. The melting process itself benefits from enhanced control when using a metal rod. The system can precisely control the melting of small volumes at the rod tip while maintaining a consistent temperature. A vertical feed arrangement allows for gravity-induced droplet formation, and rotation of the rod ensures uniform melting.

[0097] Figure 1d shows a metal production assembly 160. The metal production assembly 160 is movable by a motion system 134, for example, shown in Figure 1c. The metal depositor 120 is shown in Figure 1d as a metal source in the form of a metal rod 164, a rod holder 166, and a source heater 168 (source melter). The source melter 168 is implemented, for example, as a solenoid-shaped induction heater surrounding the rod 164. The metal rod 164 is supported by a rod holder 166, which can adjust the vertical position of the rod 164 within the metal processing assembly 160 (moving the rod up and down along the supply axis PA of the metal processing assembly 160). The rod holder 166 can rotate the rod 164 around the supply axis PA.

[0098] In the embodiment shown in Figure 1d, the metal depositor, surface heater, powder introduction unit, and inert environment unit are physically connected, for example, by being attached to a common frame 162 or by being physically mounted to one another.

[0099] In some embodiments, a system controller 136 (shown in Figure 1c) controls the generation and accumulation (deposit rate) of a second volume by controlling the operation of the source heater 168, the vertical arrangement of the rods 164 within the metal production assembly 160 (by element 166), and the spatial arrangement of the metal production assembly 160 relative to the upper surface of the casting in progress (by element 134).

[0100] In the embodiment shown in Figure 1d, the surface melter 116 (shown in Figure 1a) is realized as a pancake-shaped induction heater 172 having an opening O. The induction surface heater 172 is physically connected to the depositor 120 (e.g., connected to a common frame 162) and positioned so that the feed axis PA crosses the opening O. Preferably, the induction heater 172 has circular symmetry and is arranged concentrically around the feed axis PA, but this is not necessarily the case. The induction heater 172 may comprise single-turn or multi-turn induction coils. In some embodiments, the surface induction heater 172 comprises a circular multi-turn coil having an inner diameter of at least 30, 40, or 50 mm and an outer diameter in the range of 40 to 120 mm. The size and shape of the surface induction heater 172 affect the size and shape of the melting zone 22 (shown in Figure 1a) generated by the surface induction heater 172 within the working area WA (shown in Figure 1b). In the example of continuous melter / depositor scanning, the size and shape (width, length, depth) of the melting zone 22 generated by the surface induction heater 172 within the work area WA is further determined by operating parameters controllable by the system controller 136, such as the movement speed of the surface induction heater 172 generated by the motion system 134 (which is the same as the speed of the depositor when the surface induction heater 172 is physically connected to the depositor 120), the height above the work area (adjustable by the motion system 134), and electrically and magnetically controlled parameters (e.g., current, frequency, etc.).

[0101] The powder introduction unit 124 shown in Figure 1c is realized in the embodiment of Figure 1d as a powder introduction unit 170 having an off-axis nozzle 170a directed to deliver an amount of at least one casting property modification powder onto the melting zone 22 through the opening O of the surface melter 172.

[0102] Figure 1e shows additional details of the bottom of the metal production assembly 160 in Figure 1d. The following elements of the powder introduction unit 170 are shown in Figure 1e, with the supply straw 177 ending at the supply nozzle 178. The supply straw 177 is placed in a supply straw cover 177a made of heat-resistant material, at least in part. The supply nozzle 178 is placed at a standoff distance SD on the object region 184 and is inclined with respect to the molten zone at an angle α. The supply nozzle 178 is positioned so that a desired spot size of the casting property modification powder input amount PD is introduced onto the molten zone 182 through the opening O and in proximity to the supply axis PA of the metal processing system 160.

[0103] In the exemplary embodiment shown in Figure 1e, the powder nozzle 178 is shown to extend slightly into the opening O of the surface heater 172. However, this is not necessarily the case. In some embodiments, the powder nozzle 178 extends deep into the opening O. In other embodiments, the powder nozzle 178 passes through the opening O and extends slightly below the bottom surface of the surface heater 172.

[0104] Figure 1f is a bottom section of another embodiment of the present disclosure, showing a metalworking assembly 190 incorporating a dual feed configuration. Two feed straws 192-1 and 192-2 are shown, each ending in respective feed nozzles 194-1 and 194-2 positioned at different locations in the XY plane. The feed straws 192-1 and 192-2 have an azimuthal displacement of 90° with respect to the feed axis PA, but this is not necessarily the case, and other spatial arrangements can be implemented. In some embodiments, some powder is delivered through powder nozzle 194-1 and some through powder nozzle 194-2. The powder straws 192-1 and 192-2 may have similar or different powder delivery angles. The powder straws 192-1 and 192-2 may extend into the opening O in the same or different ways. The respective powder spot sizes delivered through feed nozzles 194-1 and 194-2 may be similar or different. In some embodiments, physically connected surface heaters and metal depositors have rotational degrees of freedom around the supply axis PA, and each powder nozzle is actuated according to its rotational position. In some embodiments, powder nozzles 194-1 and 194-2 can be operated in parallel, for example, each delivering different powders or the same powder. The disclosure is not limited to the number of supply nozzles, and two or more supply nozzles may be incorporated.

[0105] In some embodiments, a coaxial supply configuration (coaxial with respect to the supply axis PA) is incorporated. The coaxial supply configuration may include one or more feeders.

[0106] During the operation of the system illustrated in Figures 1d-1f, the source heater 168 heats the rod 164, for example, heating the tip and shoulder regions of the rod 164 (source heating). Accordingly, the molten metal MD drips onto the work area / melting zone 182 (deposit location) in discrete droplets, continuous droplets, or flow. The melting heater 172 heats and melts the previously solidified metal in the work area, creating the melting zone 182. The position, volume, shape, and temperature of the molten metal voxels 182 (melting zone) under the influence of the melting heater 172 and the source heater 168 can be sensed (sensor 176 shown in Figure 1d). The readings of the sensed parameters may be used by the system controller 136 (shown in Figure 1c) to control the source heater 168 and the surface heater 172. The deposit flow rate is a function of the moving speed of the rod in the metal production assembly 160 on the work area. The readings of the sensed parameters may be used by the system controller to control the movement speed of the metal production assembly 160 on the work area.

[0107] The system controller 136 may further be configured to implement a continuous scanning mode in which the metalworking assembly moves continuously along a processing path while maintaining a dynamic melting zone, and a discrete scanning mode in which the metalworking assembly sequentially processes separate work areas, the controller selecting the scanning mode based on at least one of the geometric shape, thermal requirements, or material properties of the part.

[0108] The system controller 136 may be further configured to adjust scanning parameters in response to real-time thermal feedback, maintain a minimum melt zone volume specific to each scanning mode, adjust the timing of powder introduction depending on the selected scanning mode, and manage thermal conditions at the boundaries between adjacent work areas.

[0109] Referring here to Figure 1g, flow chart 1000 illustrates a method of multilayer metal casting according to an embodiment of the present disclosure. The method is intended to produce a metal object by generating a stack of production layers having mold regions and object regions, the mold regions comprising a mold in progress, and the object regions comprising a casting in progress retained within the mold in progress.

[0110] This method involves iteratively constructing a continuous production layer, each production layer consisting of two main operations. In the first main operation 1002, the template area of ​​the current production layer is constructed on top of the production layer stack. In the second main operation 1004, the object area of ​​the current production layer is processed.

[0111] The processing of object region 1004 involves a series of operations performed on one or more work areas within the object region. These operations include, in 1006, melting a first volume of previously solidified metal in the casting in progress and dropping a second volume of molten metal into the first volume. The first and second volumes accumulate in a molten zone having at least a predetermined minimum volume of molten material necessary for the casting property modification process.

[0112] Once the molten zone is established, the method proceeds to operation 1008, in which an allocated amount of at least one casting property modifying powder is delivered into the molten zone. The method continues with an optional operation 1010 to maintain the molten zone in a molten state for a predetermined minimum duration, and in operation 1012, to maintain the molten zone in an inert environment while it is in a molten state. For a single work area, surface heating may occur before (pre-deposition heating) and / or after (post-deposition heating) metal deposition. Melting may be achieved during pre-deposition heating, during metal deposition, and during post-deposition heating.

[0113] As indicated by the annotation in Figure 1g, these operations are performed on one or more work areas within the object area, and the entire process is repeated for all production layers until the metal object is complete. The hierarchical arrangement of operations 1006, 1008, 1010, and 1012 within operation 1004 illustrates the sequential and simultaneous nature of the metalworking processes performed within one or more work areas constituting the object area of ​​each production layer.

[0114] The sequence of operations 1006, 1008, 1010, and 1012 is performed until the entire object region of the current production layer is prepared. In production scenario 10 shown in Figure 1a, where the entire object region of the current production layer is processed together, the sequence of operations 1006, 1008, 1010, and 1012 is performed once for the current production layer. In production scenario 12 illustrated in Figure 1b, where a portion of the object region of the current production layer is processed sequentially while the metal processing system scans the current production layer, the sequence of operations 1006, 1008, 1010, and 1012 is performed several times for each production layer.

[0115] As shown in relation to embodiments considered with reference to Figures 1d-1f, the casting property modification powder is supplied discretely while the depositor continuously drops molten metal, and the melter continuously melts the working area as the metalworking assembly scans the current production layer. Some embodiments of the present disclosure are not limited to this method of operation.

[0116] After the entire material area of ​​the current production layer has been processed and before proceeding to the construction of the mold area of ​​the next production layer, the casting in progress is cooled (operation 1014). In some embodiments of the present disclosure, the casting in progress is cooled from a metalworking temperature, e.g., 1150-1300°C for iron and iron alloys, to a mold construction temperature, e.g., approximately 700, 600, 500, 400, 300, and 200°C for in-situ mold construction using ceramic materials. In some embodiments, the temperature of the top surface of the casting in progress is sensed, for example, by a thermal camera (sensor 176 shown in Figure 1d), and method 1000 repeats the mold construction (operation 1002) to metalworking (operation 1004) only if the temperature of the top surface of the casting in progress indicates an appropriate temperature.

[0117] Different metal cool-down durations and different mold construction temperatures may be set for different production layers.

[0118] Powder distribution and introduction Figure 2a is a schematic diagram of the powder introduction system 200 (generally shown as element 106 in Figure 1a, element 124 in Figure 1c, and partially shown in Figures 1d-1e). The powder introduction system 200 serves to introduce the casting property modification powder (inoculant and / or additive powder), abbreviated herein as “powder” (as described with reference to Figures 1a-1e), into the molten zone. In some embodiments, the powder introduction system 200 is gas-assisted. The casting property modification powder is delivered by spraying one or more powder shots / intakes into the molten zone. Each powder shot is delivered with sufficient kinetic energy to overcome the surface tension of the molten zone. Upon delivery, the powder melts into the molten zone. The molten metal dripping into the molten zone can impart additional heat to the molten zone and support agitation and homogeneous dissolution of the powder particles in the molten material.

[0119] Various elements of the gas-assisted powder introduction system 200 are shown in Figure 2a. These include a gas (N2) reservoir 202, a pressure gauge 204, an N2 flow meter 206, and an N2 valve 208. Each also includes a powder injector for inoculants / additives and other casting property modifiers (reservoir) 210i (i=1, ..., n), equipped with an injection mechanism (e.g., valve 212i (i=1, ..., n)) for providing a desired amount of powder and monitoring the remaining powder, and a sensor (not shown). Micro-injections are provided at levels ranging from a few micrograms to several maggrams per injection. For example, from 1-2 micrograms to 2, 5, and 10 grams per injection.

[0120] The powder content to be delivered is collected and included in the inspection volume 214.

[0121] Upon delivery, the delivered powder is pressurized through the connector 216 toward the powder nozzle 218. The powder nozzle 218 is physically connected to the depositor (element 126 shown in Figure 1a). The powder nozzle 218 is directed toward the work area. The center of the powder nozzle 218 may be directed toward the center of the work area (molten zone). The powder flow / input amount PD is discharged, for example, blown into the molten material.

[0122] Depending on the geometric specifications of the deposition area (e.g., the geometric specifications of the rod tip, melting heater, surface heater, working distance of various elements corresponding to the melting zone, etc.) and the powder characteristics (e.g., particle size), the respective powder delivery force (gas pressure), powder delivery angle α, and powder nozzle standoff distance SD are defined.

[0123] The powder delivery angle α is crucial for optimal powder penetration and distribution in the molten zone. Typically, the delivery angle ranges from 15° to 75° from the horizontal, with the optimal range being 30° to 60° for most applications. The powder delivery angle α range is determined based on factors such as (i) the surface tension characteristics of the molten zone, (ii) the required powder penetration depth, and (iii) the dynamics of the gas flow.

[0124] The standoff distance (SD) depends on the desired powder delivery spot size, as well as the spatial relationships between the mold area, the object area, and various layered casting system elements, such as the surface heater and the molten metal depositor. Powder flow divergence and gas forcing characteristics should also be considered.

[0125] The powder delivery spot size 226 can be set considering the following factors: melting zone dimensions and thermal conditions, required powder distribution pattern, and additive distribution and concentration requirements.

[0126] For example, the spot size 226 of the powder nozzle 218 may be in the range of 2-50 mm in diameter, and the standoff distance SD may be in the range of 12-60 mm. The powder delivery angle α may be in the range of 15-75° with respect to the melting zone.

[0127] This system achieves a powder capture efficiency in the range of 75-95%, which is significantly higher than conventional powder-based additive manufacturing methods. This high efficiency is achieved, for example, by (i) geometric optimization: precise alignment of the powder flow with the center of the melting zone, optimization of the delivery angle relative to the melting surface tension, and control of the consistency of the powder flow; (ii) optimization of process parameters such as gas pressure, powder particle size distribution, and gas flow rate; and (iii) timing synchronization of, for example, melting zone formation and powder delivery delay time.

[0128] In embodiments of the present disclosure not shown in Figure 2a, the powder delivery system may further include one or more of the following: (1) real-time powder flow rate monitoring, (2) feedback control of the powder delivery rate, and (3) thermal protection elements.

[0129] The casting property modification powder may include chemical modification materials and / or metallurgical modification materials.

[0130] Regarding the treatment of cast iron alloys, the casting property modification powder material may be one or more powder materials selected from the group consisting of (1) grain refiners made of titanium alloys, zirconium alloys, and niobium alloys, and / or (2) inoculants made of ferrosilicon, aluminum, silicone carbide, calcium, strontium, cerium, sodium, barium, and rare earth elements, and / or (3) deoxidizers made of aluminum, silicon, manganese, and calcium, and / or (4) microstructure modifying agents made of magnesium, cerium, lanthanum, and yttrium, and / or (5) carbide forming agents made of vanadium, titanium, tellurium, tungsten, and molybdenum.

[0131] For the treatment of steel and / or steel alloys, the casting property modification powder material may be one or more powder materials selected from the following: (1) grain refiners consisting of aluminum alloys, titanium alloys, zirconium alloys, and niobium alloys; and / or (2) oxygen scavengers consisting of aluminum, silicon, manganese, and calcium; and / or (3) microstructure modifiers consisting of magnesium, cerium, lanthanum, and yttrium; and / or (4) carbide-forming agents consisting of vanadium, titanium, tungsten, molybdenum, and niobium; and / or (5) corrosion resistance modifiers consisting of chromium, nickel, molybdenum, silicon, aluminum, titanium, niobium, and phosphorus.

[0132] Casting property modification powder is provided to a treated metal to initiate a casting property modification process, such as (1) controlled graphite nucleation and growth to achieve a predetermined graphite morphology and / or distribution, (2) controlled phase transformation resulting in a predetermined phase ratio, (3) in-situ chemical composition modification to achieve predetermined local material properties, (4) grain refinement resulting in enhanced mechanical properties, (5) precipitation hardening, or (6) a controlled solidification process resulting in a predetermined dendrite arm spacing, or a combination thereof.

[0133] The quantitative relationship between additive concentration and the resulting properties has been established through decades of industrial practice and academic research. These established relationships provide a reliable basis for predicting and controlling the effects of additives in casting metals, making them particularly suitable for implementation in controlled voxelization casting processes. The challenge lies not in understanding what effects will be achieved, but rather in precisely delivering the known amount of additive at the right time and place during the voxelization casting process.

[0134] According to embodiments of the present disclosure, the type and mass of the casting property modifying powder for a given volume of metal in a particular production layer are obtained based on known additive concentrations.

[0135] The amount of powder delivered to a specific work area within a particular production layer correlates with the molten metal voxel, which is the volume of molten metal in the molten zone ready to receive that amount of casting property modifying powder, according to the additive concentrations and geometric configuration details of the system known in the art (powder nozzle standoff distance, powder delivery angle, and capture efficiency).

[0136] For optimal process control, powder introduction should be performed when the melting zone conditions are optimal, the desired voxel volume (at least the minimum voxel volume) is accumulated, and the appropriate melting zone temperature is achieved.

[0137] In some embodiments of the present disclosure, the introduction of powder into a molten zone generated in a specific work area during processing is defined by a production layer powder supply plan. According to embodiments of the present disclosure, the powder supply plan is determined by a two-step determination process illustrated in Figure 2b. In the first step, the allocation of a specific production layer and a specific input amount to the supply area are determined for the specific production layer. In the second step, the allocation of a specific input amount to the supply area is determined for the specific production layer.

[0138] Figure 2b shows a method 1200 for allocating an allocated amount of at least one casting property modification powder to the molten zone in a casting in progress while generating the molten zone of the current production layer of a production layer stack having a mold region and a molten zone, the mold region comprising the mold in progress, the molten zone comprising the casting in progress held within the mold in progress, and the molten zone comprising a first volume of molten, previously solidified metal and a second volume of newly added molten metal in the casting in progress. Method 1200 begins with operation 1202 for each production layer, acquiring the following data items. (1) a target property desired in the final casting, and (1a) fading characteristics of at least one casting property modifying powder used, (2) object area volume, (3) volume of previously solidified metal to be remelted, and (4) operating parameters of the metal processing assembly (processing path, metal processing assembly rate, deposition rate, heater parameters) that affect the melting rate of the volume of previously solidified metal.

[0139] Volume of previously solidified metal to be remelted: As described, the operations performed in the production of the material region of the currently produced production layer affect the previously produced material region of the previously produced production layer. In some embodiments of this disclosure, the depth of the melting zone is designed to extend the height of the currently produced production layer. Thus, the previously produced material region of the previously produced production layer is remelted.

[0140] For illustrative purposes, in some embodiments, the height of the production layer currently being produced may be in the range of, for example, 3 mm to 12 mm. For example, in the case of a layer height of 8 mm, the production of production layer i involves, for example, remelting the metal deposited during the production of production layers i-1 and i-2.

[0141] Fading characteristics of at least one casting property modifying powder under reheating and remelting: The type of casting property modifying powder, in particular its response to heating and remelting, is also considered. Some casting property modifying powders are heat-sensitive and are affected by fading during subsequent reheating and remelting cycles inherent in the layered casting process. When a portion of previously solidified metal treated with a heat-sensitive casting property modifying powder is reheated above its melting temperature, the effectiveness of the pre-added powder decreases according to a characteristic fading rate. This fading is due to various metallurgical phenomena, including oxidation, evaporation, and chemical decomposition of active elements in the powder. To compensate for this fading effect, embodiments of the present disclosure implement an adaptive powder introduction strategy, where the allocated amount of casting property modifying powder delivered to a particular molten zone is adjusted based on (1) a predetermined fading rate of the particular powder used, (2) the thermal history of the previously solidified metal in the molten zone, including the number and intensity of reheating cycles experienced, and (3) the desired target properties in the final casting. This adaptive strategy ensures consistent metallurgical and mechanical properties throughout the casting, despite the cumulative effects of repeated thermal cycling on the active elements in the casting property modification powder.

[0142] For example, in a production scenario that includes an xy production plan (homogeneous distribution within a specific production layer) and a homogeneous distribution of target characteristics along the Z direction (uniform distribution across all production layers), as well as one remelting cycle of the first volume with the same value for the second volume, each production plan using fading powder A and non-fading powder B may include providing amounts of fading powder A allocated to the first volume (remelting) and the second volume (newly added), and providing amounts of fading powder B allocated only to the second volume (newly added).

[0143] Processing Path - Definition of the Working Area to be Processed: With reference to the scanning patterns provided with reference to Figures 1a-1b, and with regard to embodiments of the present disclosure employing continuous scanning patterns and discrete powder introduction patterns for a metal processing system, the definition of the working area to be processed includes the following data items for each production layer: (4.1) Melting Zone Creation Plan - Number of working areas (e.g., referring to a molten zone planned as “Current Working Area”); (4.2) xy position of each working area - e.g., used by the system controller to control and adjust the operation of at least the metal depositor, melter, and powder introduction unit while the metal processing system scans the current production layer; (4.3)(4.4) Volume of the molten zone generated in the working area, including a first volume of previously solidified metal to be remelted, and (4.5) a second volume of molten metal to be added to the molten zone generated in this working area.

[0144] The amount of powder allocated to the current production layer is determined based on the above data items and the known quantitative relationship between the concentration of the casting property modifier and the resulting properties.

[0145] After the amount of powder allocated to the current production layer is determined in operation 1202, the method proceeds to operation 1204, which determines the number and location of powder introduction points and the allocation of powder to specific melt zones generated in the current production layer.

[0146] In some embodiments of this disclosure, the production layer powder supply plan includes determining the number and location of powder introduction points and allocating powder to specific melting zones. This can be done by ensuring synchronization of powder allocation and melting zone creation by optimizing the synchronization of the conditions listed below.

[0147] (1) Melting Zone Accumulation Time: Timing of the supply of powder to the molting zone: Ensure that the minimum period required for the formation and stabilization of the minimum volume (metallurgically viable molten metal voxel within the work area) is provided. This condition reflects the accumulation nature of molten zone formation, which is the time required for the accumulation of molten metal due to melting and deposition. For example, in the case of gray cast iron with 2 cc voxels, the accumulation time is in the range of 1 to 10 seconds.

[0148] (2) Powder introduction delay time: This time is used to time the introduction of the powder amount after the powder introduction delay time has elapsed. The powder introduction delay time represents the total time required between consecutive powder discharges. The powder introduction delay time consists of the time required for various components of the powder introduction unit to operate during consecutive operations. For example, the delay of the powder introduction unit is affected by, for example, the mechanical response time of the dosing mechanism (valve, actuator), the powder properties (flowability, particle size), and the amount of powder to be discharged. Other factors include the time it takes for the powder to pass through the delivery tube, inspection volume, and supply nozzle. Other factors include the geometric shape of the system and the characteristics of the gas flow. According to embodiments of this disclosure, the powder introduction delay time is, for example, in the range of 0.1 to 1 second, which results in the supply of 1 to 100 powder amounts per 2cc melt zone.

[0149] In some embodiments of this disclosure, the following conditions are also considered to simplify process control over dynamic parameters (e.g., current supplied to surface heaters, heater speeds in their progression across the working area along the deposition path (which are the same as the deposition speed), and working distance (associated with the deposition distance), deposition rate, current supplied to source heaters, and deposition distance:

[0150] (3) Optionally, maintain the values ​​of the operating parameters of the metalworking assembly within an acceptable range. For example, maintain substantially fixed operating parameter values ​​for each production layer; fixed depositor / surface heater speed, fixed depositor / surface heater working distance, and fixed surface heater and source heater current supply, and allow the operating parameters to be adjusted within a predefined threshold around these fixed operating parameter values.

[0151] In some embodiments, the powder may be introduced into the work area in a single pass, with a single shot being delivered to the molten zone generated in the work area. In other embodiments, the powder may be introduced into the work area in several passes, with multiple shots being delivered to the molten zone. In yet another embodiment, the powder may be introduced into multiple work areas in a single pass, for example, two, three, or four work areas. The powder mass in each shot is adjusted as needed.

[0152] In some embodiments employing one or more feed nozzles, multiple shots may be assigned between different feed nozzles, thereby enabling additional operational flexibility.

[0153] Simultaneously with metal deposition and metal remelting, the powder nozzle 184 selectively delivers casting property modification powder to the currently producing work area (molten zone). In some embodiments, the casting property modification powder can be delivered to any work area (continuous powder delivery mode). In other embodiments, the casting property modification powder can be delivered to a selected work area (discrete powder delivery mode).

[0154] In some embodiments, a single powder input per work area is provided in both continuous and discrete powder delivery modes. In other embodiments, multiple powder shots are provided per work area.

[0155] In some embodiments, the coverage area (spot size) of the powder shot depends on the delivery plan, and the powder shot coverage area in discrete powder delivery mode may be larger than that in continuous powder delivery mode.

[0156] In some embodiments, the coverage area of ​​the powder shot may have a diameter in the range of 2 to 50 mm.

[0157] In some embodiments, all delivered powder shots have the same contents of the casting property modification powder. In other embodiments, the exact contents of the casting property modification powder delivered to a particular work area differ from those delivered to a different work area in order to provide the desired microstructure, geometric shape, composition, and mechanical properties as defined by the molding plan.

[0158] Precise powder delivery to a properly formed molten zone is key to optimal casting property modification, consistent metallurgical results, and process reproducibility.

[0159] Accordingly, according to embodiments of the present invention, the following operating parameters are sensed (for example, by the sensor 140 shown in Figure 1a): for example, the position of the depositor and surface heater by a position sensor, and the operating distance; for example, the deposit rate by a weight sensor that senses the weight of the metal source (metal rod); current supply; and the temperature of the melting zone (for example, a thermal camera). The powder introduction unit may also be equipped with appropriate sensors (not shown in Figures 1c, 2a-2b) for sensing the presence of powder in various elements of the powder introduction unit, such as the feeder, inspection volume, supply connection, straw, and nozzle.

[0160] According to an embodiment of the present invention employing a motion sensor, the satisfaction of the operating conditions for powder introduction is dynamically sensed. If the operating conditions for powder introduction are not met, the system controller may adjust one or more of the following operating parameters: deposition / surface heating rate, deposition / surface heating working distance, surface heating current supply, and source heating current supply.

[0161] Embodiments of this disclosure are useful for processing large metal parts. For illustrative purposes, in some embodiments, 3, 5, 10, 20, 30, 40, and more layer-forming iterations can be performed. In some embodiments, the layer height may range from 2 mm to 12, 15, or 20 mm. The molten zone width may range from 4 to 100 mm, the molten zone length from 4 to 100 mm, and the molten zone depth from 2 to 50 mm or more. For example, the depth of the molten zone can be extended up to a maximum of 120 mm (the upper limit of the volume of voxels to be melted and remelted depends, among other factors, in particular, on the ability of each mold area to withstand the metal heating and reheating cycles without failure). The amount of molten metal to be reheated and remelted in the production of a single working area (voxel) may be 1 cc, 2 cc, 5 cc, 10 cc, and more, up to a maximum of 100 cc (about 14 to 720 grams of gray cast iron).

[0162] Discussion of experimental results: Multilayer metal casting with the application of additives and inoculants Aspects of this disclosure will be further described with reference to Figures 3a-3b, 4a-4g, and 5a-5b showing experimental results. Two experiments were conducted to demonstrate the effects of applying inoculants and additives on the mechanical, physical, chemical, and microstructure properties of as-cast gray cast iron produced according to embodiments of this disclosure. A third experiment was conducted to illustrate the implementation of Mg treatment of ductile iron according to embodiments of this disclosure.

[0163] Experiment 1 involved casting a metal test block and a metal reference block measuring 40 mm in length, 100 mm in width, and 40 mm in height. Each component was made from five metal layers, each 8 mm high. Experiment 2 involved casting a metal test block and a reference block measuring 40 mm in length, 100 mm in width, and 88 mm in height. Each component was made from eleven metal layers, each 8 mm high. The average process temperature in the metal region was 1320°C. The rate of the metal depositor (and the surface heater connected to it) ranged from 2.5 to 8.3 mm / second.

[0164] Metal test blocks were cast using a gray iron rod with the addition of casting property modifying powder, employing a casting machine employing the embodiments of this disclosure as discussed with reference to Figures 1a-1g and 2a-2b. Various test blocks were produced by adding powder under various test plans. The added powder was introduced using an automated powder introduction system and powder allocation method as discussed with reference to Figures 2a-2b. The powder introduction system provided the powder at a predetermined concentration into a continuous molten zone during the part lamination casting process. A set of reference blocks manufactured without the addition of casting property modifying powder was produced.

[0165] The amount of molten metal treated in the production of one production layer of the test block ranged from 2.5 to 100 cc (15 to 700 grams). Discrete application of powder (2 to 10 powder shots along the production layer) was performed. The same input metal (similar gray cast iron rods) was used in the production of the reference block and the test block. The properties of the reference block and the test block were analyzed according to the ASTM E3 Standard Guide for Preparation of Metallographic Specimens.

[0166] Figures 3a-3b relate to Experiment 1, in which additional inoculi were added to affect the distribution of graphite in various parts of the test block and its relevant impact on performance. Commercially available reactive inoculi that are effective in small amounts and have short dissolution times were investigated. Representative results are shown in Figures 3a-3b.

[0167] Microstructure images 302, 304, and 306, taken at 50x magnification from the top, middle, and bottom of the test block, respectively, and microstructure image 308 of the bulk portion of the test block, taken at 200x magnification, show a uniform distribution of graphite types A and B, as well as a fine matrix of complete perlite. This is also shown in microstructure images 332, 334, and 336, taken at 100x magnification from the top, middle, and bottom of the test block, respectively, and microstructure images 338 and 340 of the bulk portion of the test block, as well as microstructure images 338 and 340, taken at 500x and 100x magnification, respectively. Block section labels 330 label each microstructure image.

[0168] The tensile measurement results 310 and hardness profile 320 reflect the microstructure results, indicating that enhanced mechanical properties (hardness and tensile strength) have been obtained in the bulk material.

[0169] The results of Experiment 1 demonstrate that the addition of the inoculant according to the embodiments of this disclosure is carried out with good control of the addition rate, good stirring of the inoculant in the molten material, and homogeneous dissolution.

[0170] Figures 4a-4h relate to Experiment 2, in which a Cu alloy (Cu-based additive) was added to affect the distribution of pearlite in the casting. Chemical analysis, chemical composition distribution, microstructure, and mechanical properties were performed on the test block and reference block.

[0171] Table 400 shows the chemical composition results for comparison between the reference sample, test sample, and source sample (the input gray cast iron rod). Chemical composition analysis was performed using optical emission spectroscopy (OES-HITACHI Optical emission spectrometer FOUNDRY-MASTER smart), and carbon content was specifically analyzed using thermal analysis.

[0172] The results reveal several important findings.

[0173] Baseline element consistency: The major elements (C, Si, Mn) showed clear consistency across all samples. Carbon was maintained at 3.15–3.18 wt%, silicon at 2.62–2.75 wt%, and manganese at 0.748–0.76 wt%. This consistency validates the stability of the process and confirms that the introduction of additives did not alter the base composition.

[0174] Intentional compositional modification: The test samples showed a significant increase in specific elements: copper increased from 0.083% (reference) to 1.03% (test), and tin increased from 0.075% (reference) to 0.20% (test). These increases directly correspond to the intentional addition of Cu-based additives.

[0175] Other elements remained remarkably consistent between the reference and test samples: chromium was at a level of 0.063% in both samples, nickel: 0.0311% vs. 0.0302%, and titanium: 0.0133% vs. 0.0136%. The carbon equivalent (CE) values ​​remained stable across all samples: source sample: 4.08, reference: 4.03, test: 4.06. This stability indicates that the introduction of additives did not significantly affect the overall solidification properties.

[0176] Figure 4b shows the results of chemical composition distribution analysis performed along the XZ cross-section of the test sample. Multiple measurement points were systematically positioned at various heights from the bottom of the sample across cross-section 410(a), and optical emission spectroscopy (OES) measurements were performed. By distributing the analysis points, both vertical (Z direction) and horizontal (X direction) distributions were captured. A schematic diagram of the OES trace analysis with the corresponding analyzed chemical composition (Cu%) is shown in Figure 410(b).

[0177] The analysis reveals consistent Cu concentrations across different locations. In the bottom production layer constituting the test specimen, the Cu concentration is approximately 1.040–1.120 wt%. In the center of the test specimen, the Cu concentration is approximately 1.040 wt%. In the upper production layer, the Cu concentration is approximately 0.976–0.930 wt%. The measurements demonstrate a nearly uniform distribution of additive elements along the z direction, consistent with (1) the addition of a fixed amount of copper in all molten zones of all production layers, and (2) the thermal cycling and mixing variations experienced by each of the production layers. Due to the layered nature of production, the bottom production layer experienced additional thermal cycling compared to the upper production layer. Thus, the overall mixing of copper in the molten metal of the bottom production layer is improved compared to the mixing of copper in the molten metal of the upper production layer. Minimal variation was observed between different spatial locations along the x direction. Similar results are obtained in measurements performed along the yz cross section (not shown). The results suggest that if the amount of additive supplied to the molten zone of a particular production layer correlates with the height (distance from the bottom) of that particular production layer, a uniform distribution of additive elements across the entire test block may be achieved.

[0178] Figures 4c and 4d show the metallographic examination results of the test specimen (Figure 4c) and the reference specimen (Figure 4d). Metallographic examination was performed on specimens prepared according to the ASTM E3 standard specification, which included cutting perpendicularly along the XZ plane and grinding and polishing to a surface finish of 1 μm. The specimens were examined under both unetched and etched conditions, and etching was performed using a 3% Nital solution. Microstructure characteristics were evaluated using an optical microscope at magnifications of 50x for representative fields, 100x for graphite size evaluation, and 500x for detailed matrix examination. A comparison of the microstructure between the test specimen and the reference specimen after chemical etching at high magnification is shown in Figure 4e.

[0179] Results I and II are the metallographic examination results, which are evident in Figures 4c and 4e.

[0180] Results I - Evaluation of the microstructural characteristics of the two parts showed a clear pattern of graphite distribution along the Z direction for both the reference sample (Figure 4c) and the test sample (Figure 4d).

[0181] (1) The bottom and vicinity of the component (0-30 mm from the molded plate) exhibited type VII graphite, mainly type A morphology and isolated type D regions, with graphite size evolving from class 3 to class 5-6. The matrix structure of this region showed evidence of eutectic cells rich in partially dissolved pearlite and ferrite.

[0182] (2) The microstructure in the 40-70 mm range is characterized by a fine D / E type graphite distribution of class 5-7 size.

[0183] (3) The upper microstructure is characterized by an A / D / E type graphite distribution of class 5-6 size.

[0184] The graphite distribution pattern along the Z-direction for both the reference and test samples is primarily due to the thermal circulation properties of the additive casting technique.

[0185] Results II - Microstructural analysis revealed clear differences in the matrix structure between the reference sample and the test sample.

[0186] In the reference sample, examination from the bottom to the center (0–40 mm from the building plate) revealed significant pearlite degradation, characterized by randomly oriented dendritic structures and ferrite-rich eutectic cells against a background of partially dissolved pearlite. This reduction in microstructure may be attributable to the cumulative effect of repeated thermal cycling and prolonged exposure to high temperatures inherent in the lamination casting process. The central height region (60–70 mm from the building plate) maintained a similar randomly oriented dendritic structure with ferrite-rich eutectic cells, but with a marked transition to a background of lamellar pearlite. The upper region (approximately 80 mm from the building plate) exhibited a complete lamellar pearlite structure.

[0187] In contrast, test specimens treated with Cu-based additives demonstrated significantly improved microstructural stability and refinement. The addition of Cu-based additives resulted in three major microstructural modifications: (i) a substantial reduction in pearlite dissolution, (ii) refined interlayer spacing within the pearlite structure, and (iii) an increase in the pearlite-to-ferrite ratio, effectively eliminating the formation of ferrite-rich eutectic cells observed in the reference specimen. The bottom to central region (0–40 mm from the molded plate) exhibited only minimal pearlite dissolution, with the matrix primarily consisting of lamellar pearlite. The central to upper region (40 mm to the top surface) featured a consistent, fine lamellar pearlite structure, demonstrating excellent microstructural stability throughout the entire height of the molded product.

[0188] The clear differences in matrix structure between the reference sample and the test sample revealed in microstructural analysis indicate that the addition of Cu-based additives according to the embodiments of this disclosure reproduced the effect of Cu on the casting microstructure, as expected in conventional castings.

[0189] Figure 4f shows macroscopic images of the reference sample (Image 476) and the test sample (Image 477) after chemical etching.

[0190] (1) Observation of the macrostructure shows good metallurgical bonding between all metal layers produced by the additive casting technique of this disclosure. Both samples exhibited sound metallurgical bonding between consecutive layers, and there were no observable casting defects such as cracking, lack of fusion, shrinkage, or porosity. The sound metallurgical bonding between consecutive layers obtained for both the test and reference samples demonstrates the reproducibility of the additive casting process during intralayer metalworking (XY plane: successive working areas within the same production layer) and interlayer metalworking (Z direction: one production layer on another production layer).

[0191] (2) Macrostructure observation further reveals ferrite-rich zones observed in the etched cross-section of the reference sample. This is also evident from the 50x magnified image shown in Figure 4c. The addition of Cu alloy during the fabrication of the test sample eliminated the formation of ferrite-rich eutectic cells. This is also evident from the 50x magnified image shown in Figure 4d and the 500x magnified image shown in Figure 4e.

[0192] Figure 4g shows the Brinell hardness measurement results for the reference and test samples as a function of distance from the bottom of the sample. Hardness measurements were performed using the Brinell hardness test method, with a SUN TEC Brinell hardness tester model DLC-3100, in accordance with ASTM E10. The test parameters used were a 2.5 mm indenter (HBW2.5 / 187.5) with a load of 187.5 kgf, selected due to the constraints of the sample width, excluding the standard 3000 kgf load specified in ASTM E10.

[0193] Results III - Hardness measurements revealed a significant improvement in hardness properties due to the addition of Cu-based additives. While the reference sample exhibited an average hardness value of 183 ± 22 HBW, the test sample demonstrated a considerably higher average hardness value of 247 ± 23 HBW. This indicates that the addition of Cu-based additives increased hardness by approximately 35%.

[0194] Result IV - The hardness distribution along the molding direction (Z-axis) showed a characteristic pattern.

[0195] (1) The reference sample shows significant variation throughout the height of the molded product. Lower region (0-20 mm): Relatively consistent hardness values ​​in the range of 148-170 HBW. Middle region (20-50 mm): Varying values ​​of 170-225 HBW. Upper region (50-82 mm): Varying between 175-220 HBW.

[0196] (2) The test specimens show a more consistent hardness profile, with a tendency to increase towards the top surface. Lower region (0-20 mm): stable value around 220-230 HBW. Middle region (20-50 mm): increasing trend from 230 to 245 HBW. Upper region (50-82 mm): highest value reaching 270-290 HBW.

[0197] The enhanced hardness properties in the test specimen may be due to several microstructural factors: (i) an increase in the pearlite-to-ferrite ratio in the matrix, (ii) a reduction in pearlite decomposition, (iii) a refined lamellar pearlite structure, and (iv) a modified graphite distribution and size classification.

[0198] Figure 4h shows the tensile measurement results for four cast samples: one reference sample with no added Cu, and three test samples: Test 1-0.5% target Cu alloy addition, Test 2-0.75%, and Test 3-1%. Tensile tests were performed at seven extraction locations on circular vertical samples with a φ4 mm parallel section and a cross-sectional length of 64 mm. Tensile tests were performed using a SHIMADZU tensile machine model AGS-100kNX in accordance with ASTM E8. The tensile measurement results obtained at the three Cu addition levels are consistent with the expected gradual strengthening of mechanical properties in response to gradual Cu addition.

[0199] The average tensile stress values ​​(MPa) of the vertical samples of the reference sample and the samples from Tests 1 to 3 are shown. The results show an increase in the average tensile stress in each vertical sample in proportion to the amount of added Cu. The tensile strength of Test 1 is 7% higher than the reference tensile strength, the tensile strength of Test 2 is 22% higher, and the tensile strength of Test 3 is 27% higher.

[0200] The results shown in Figures 4a–4h demonstrate, according to this disclosure, that the addition of Cu alloy to the molten metal during processing yields several beneficial effects. First, it significantly increases the overall hardness. Second, it promotes more consistent mechanical properties throughout the height of the molded product, as evidenced by the hardness profile. Third, microstructural analysis reveals that adding Cu alloy from a nominal 1% Cu substantially reduces pearlite decomposition, refines the interlayer spacing of the pearlite structure, and increases the pearlite-to-ferrite ratio throughout the height of the molded product. These improvements were achieved by introducing a fixed concentration of Cu-based additives during the lamination casting process, resulting in a uniform distribution of additive elements, as confirmed by chemical analysis. Enhanced microstructural stability and refined pearlite structures were observed across all production layers, demonstrating good control of the additive rate.

[0201] Figures 5a-5b refer to Experiment 3, which deals with ductile iron. Ductile iron is characterized by graphite in the form of nodules rather than flakes, like gray iron. Nodule formation is achieved by adding nodule-forming elements, most commonly magnesium (Mg). Mg boils at 1100°C.

[0202] In Experiment 3, ductile iron ingots were used as input materials for five experimental steps. In the first step of Experiment 3, the properties and microstructure of the input ductile iron were measured, and the results are shown in result set (1).

[0203] In the second step of Experiment 3, the input ductile iron ingot was heated and scanned by a surface heater (e.g., surface melter 104 shown in Figure 1a) according to an embodiment of the present disclosure. The effect of remelting on the microstructure and properties of the input ductile iron is shown in result set (2). Morphological changes of graphite due to Mg fading, oxidation, and sulfur reaction are evident. The nodularity decreases from 95% to 55%. The remelted ductile iron input serves as a reference for the third and fourth steps of Experiment 3.

[0204] In the third step of Experiment 3, the input ductile iron ingot was heated and scanned with a surface heater to provide a high-Mg concentration additive alloy according to embodiments of the present disclosure. The effects of the heat and high-Mg additive treatment on the microstructure and properties of the input ductile iron are shown in result set (3). Nodularity increases compared to the reference (result set (2)) and is maintained with a slight increase compared to the input ductile iron (result set (1)).

[0205] In the fourth step of Experiment 3, the input ductile iron ingot was heated and scanned with a surface heater to provide a low Mg concentration additive alloy according to the embodiments of the present disclosure. The surface heating conditions were applied in the fourth step, as in the third step. The effects of the heat and low Mg additive treatment on the microstructure and properties of the input ductile iron are shown in result set (4). Nodularity is increased compared to the reference (result set (2)) and maintained with a slight decrease compared to the input ductile iron (result set (1)).

[0206] In the fifth step of Experiment 3, the input ductile iron ingot was heated and scanned with a surface heater to provide a high Mg concentration additive alloy according to the embodiments of the present disclosure. Different surface heating conditions were applied compared to the third and fourth steps. The effects of heat and high Mg additive treatment on the microstructure and properties of the input ductile iron are shown in result set (5). It exhibits the microstructure and properties of compressed and denser graphite iron.

[0207] Experiment 3 demonstrates that the application of the material treatment techniques and motion control according to the embodiments of this disclosure reproduces the expected theoretical and experimental results of the general technique, for example, as shown in graph (6) of Figure 5b (quoted from Dr. Steve Dawson and Tom Schroeder, “Compacted Graphite Iron: A Viable Alternative,” published in Engineered Casting Solutions AFS Spring 2000, SinterCast 09 / 02 B-15-15-0.3).

[0208] Experiments 1, 2, and 3 demonstrate the reproducibility of additive and / or inoculation-based layered casting according to embodiments of the present disclosure. Experiments 1, 2, and 3 further demonstrate the ability to control and influence the casting microstructure and properties by controlling the operating parameters of the casting system and by processing the molten metal in a voxelized manner.

[0209] Embodiments of the present invention have been described in relation to the layered casting of gray cast iron. The present invention is not limited to the type of casting material. The present invention is applicable to the layered casting of iron alloys and other metals, including ductile iron, steel, and other metals, with appropriate modifications.

[0210] For clarity, in Figure 1a, units 126, 124, 120, and 122, and the motion system 134 are shown as single, separate entities; however, this disclosure is not limited by the type and number of each type of motion unit.

[0211] For example, in some embodiments in which one or more molten metal materials are used, multiple molten metal depositors are provided. In other embodiments in which one or more mold materials are used, multiple mold constructors are provided.

[0212] Depending on the geometric shape of the object area and the molding plan, the volume of molten metal in the molten zone of different work areas may not be identical. Therefore, the amount of inoculant and / or additive delivered to a particular work area may not be the same as the amount of inoculant and / or additive delivered to other work areas.

[0213] In the examples in Figures 1a, 1c, and 2a-2b, the powder nozzle 218 (element 184, also shown in Figure 1c) is implemented as a linear tube, but this is not always the case. Other nozzle configurations, such as a coaxial nozzle configuration, may be used.

[0214] In the examples in Figures 1c, 2a-2b, the powder nozzle 184 is shown to have a fixed powder delivery angle and a fixed standoff distance, but this is not necessarily the case. In some embodiments, the powder delivery angle and / or standoff distance may be controlled and adjusted according to the molding plan (not shown in Figure 1c).

[0215] While the application under pressure is illustrated in Figures 1c, 2a-2b, other release techniques such as powder puffing can also be used.

[0216] In some embodiments, the powder is continuously supplied to any work area. In some embodiments, the powder is supplied in a discontinuous and discrete manner within a selected work area. In one embodiment, a single powder shot is supplied to the discharge position. In other embodiments, multiple pulsed powder shots are delivered to the discharge position. The amount of powder in a shot, whether a single shot or one of multiple shots, may be adjusted as needed. Discrete, discrete powder discharge facilitates tighter control over the amount of powder supplied.

[0217] Total production throughput can be increased by operating one or more forming tables, two or more depositors per forming table, two or more mold building units per forming table, and so on. In some embodiments, several units of the same type operate simultaneously at different positions relative to the forming table 116 to handle different areas of the casting in progress. Other such configurations are possible, in particular, when there are multiple forming tables 116.

[0218] For ease of explanation and illustrative purposes, under Experiment 2 described herein, the processing plan for the entire box-shaped casting involves substantially the same processing for all production layers and substantially similar processing for all working areas within the production layers. Thus, the same amount of powder was introduced into the molten zone of the working area. It should be noted that embodiments of this disclosure are not limited to this exemplary forming plan, and other forming plans, including those involving complex geometric shapes, functions, and applications, can be implemented.

[0219] The aspects of this disclosure have been described with reference to the casting of complete parts. The additive casting techniques described herein are suitable for hybrid casting applications. In hybrid casting, a portion of the final casting is formed on top of a portion of the final part that has been fabricated by conventional casting techniques. Compared with, for example, SLM (Selective Laser Melting) and DED (Directed Energy Deposition) which have been investigated for hybrid casting, the molten metal additive casting described herein may be more suitable for hybrid casting applications.

[0220] Embodiments of the present disclosure facilitate the treatment of voxels of molten metal in amounts of 1 cc, 2 cc, 5 cc, 10 cc, and up to 100 cc by iteratively adding inoculants and / or additives in a locally controlled and highly repeatable manner at the production layer level and work area level. According to embodiments of the present disclosure, locally controlled and highly repeatable addition of inoculants and additives makes it possible to improve the microstructure, mechanical properties, and physical properties of a casting with appropriate inoculants and additives; to design and fabricate a casting with specific microstructure and mechanical properties at specific locations within the casting; to bring about the location of ductile iron in ductile cast iron or gray cast iron by magnesium treatment; and to bring about the location of white iron in white cast iron or gray cast iron by carbide accelerator treatment. As described in detail herein, the additive processes according to the present invention ensure that the continuously deposited material areas of the casting metal comply with metallurgical, mechanical, and compositional requirements.

[0221] Embodiments of this disclosure accept a metal rod as input (other forms of solid input, such as ingots, pebbles, etc., and liquid input, such as incorporating a crucible, are also preferred).

[0222] Additional embodiments of systems and methods for additive casting are described, for example, in PCT Patent Publication WO2019 / 053712A1 filed on 6 September 2018, WO2022 / 243921A1 filed on 19 May 2022, and WO2023 / 002468A1 filed on 15 May 2022, all of which are incorporated herein by reference.

[0223] Unless otherwise specified, as is evident from the foregoing discussion, throughout this specification, any discussion using terms such as “processing,” “computing,” “calculating,” and “decision” is understood to refer to actions and / or processes of any type of general-purpose computer, including client / server systems, mobile computing devices, smart appliances, cloud computing units, or similar electronic computing devices that manipulate data in the registers and / or memory of a computing system and / or convert it into other data in the memory, registers, or other such information storage, transmission, or display devices of a computing system.

[0224] Embodiments of this disclosure may include an apparatus for performing the operations described herein. This apparatus may include a computing device or system, typically having at least one processor and at least one memory, which may be specifically constructed for a desired purpose or selectively activated or reconfigured by a computer program stored in a computer. The resulting apparatus, when instructed by software, can transform a general-purpose computer into an element of the present invention as considered herein. The instruction may define the device of the present invention operating on a desired computer platform. Such computer programs may be stored on computer-readable storage media, including, but not limited to, optical disks, any type of disk including magneto-optical disks, read-only memory (ROM), volatile and non-volatile memory, random-access memory (RAM), electrically programmable read-only memory (EPROM), electrically erasable and programmable read-only memory (EEPROM), magnetic or optical cards, flash memory, disk-on-key, or any other type of medium suitable for storing electronic instructions and which can be linked to a computer system bus. Computer-readable storage media may also be implemented in cloud storage.

[0225] Some general-purpose computers may include at least one communication element to enable communication with data networks and / or mobile communication networks.

[0226] The processes and displays presented herein are not inherently related to any particular computer or other device. Various general-purpose systems may be used with the program in accordance with the teachings herein, or it may be convenient to construct more specialized devices to perform the desired method. Desired structures for various such systems can be found in the following description. Furthermore, embodiments of this disclosure are not described with reference to any particular programming language. It will be understood that the teachings of this disclosure as described herein can be implemented using various programming languages.

[0227] While certain features of this disclosure have been illustrated and described herein, those skilled in the art will likely come up with numerous modifications, substitutions, alterations, and equivalents. It should be understood that the appended claims are intended to encompass all such modifications and alterations that fall within the true spirit of this disclosure.

Claims

1. A multilayer metal casting system for casting a metal object by producing a stack of production layers having mold regions and object regions, wherein the mold regions constitute a mold in progress, and the object regions constitute a casting in progress held within the mold in progress, and the multilayer metal casting system In the casting in progress, a surface melting vessel for melting a first volume of previously solidified metal, A metal depositor for dropping a second volume of molten metal into the first volume, A metal processing system comprising a powder introduction unit for delivering an allocated amount of at least one casting property modification powder, A multilayer metal casting system in which the first volume and the second volume are accumulated within a molten zone containing at least the minimum volume of molten material required for the casting property modification process.

2. The laminated metal casting system according to claim 1, wherein the casting property modification powder includes a chemical modification material and / or a metallurgical modification material.

3. The multilayer metal casting system according to claim 1, wherein the casting property modification process includes at least one of: (1) controlled graphite nucleation and growth to achieve a predetermined graphite morphology and / or distribution; (2) controlled phase transformation to result in a predetermined phase ratio; (3) in-situ chemical composition modification to achieve predetermined local material properties; (4) grain refinement to result in enhanced mechanical properties; (5) precipitation hardening; or (6) a controlled solidification process to result in a predetermined dendrite arm spacing.

4. The laminated metal casting system according to claim 1, wherein the casting property modification process is controlled by one or more of the following: (1) maintaining the minimum volume at a predetermined temperature within a specific range for a predetermined residence time; and (2) maintaining a predetermined temperature gradient over the minimum volume.

5. The laminated metal casting system according to claim 1, wherein the molten metal is a cast iron alloy, and the powder introduction unit is configured to deliver at least one powder material selected from (1) a group of grain refiners consisting of titanium alloys, zirconium alloys, and niobium alloys, and / or (2) a group of inoculants consisting of ferrosilicon-based inoculants, aluminum-based inoculants, silicone carbide-based inoculants, calcium-based inoculants, strontium-based inoculants, cerium-based inoculants, sodium-based inoculants, barium-based inoculants, and rare earth elements, and / or (3) a group of deoxidizers consisting of aluminum, silicon, manganese, and calcium, and / or (4) a group of microstructure modifying agents consisting of magnesium, cerium, lanthanum, and yttrium, and / or (5) a group of carbide-forming agents consisting of vanadium, titanium, tellurium, tungsten, and molybdenum.

6. The laminated metal casting system according to claim 1, wherein the molten metal is steel and / or a steel alloy, and the powder introduction unit is configured to deliver at least one powder material selected from (1) a group of grain refiners consisting of aluminum alloys, titanium alloys, zirconium alloys, and niobium alloys, and / or (2) a group of oxygen scavengers consisting of aluminum, silicon, manganese, and calcium, and / or (3) a group of microstructure modifiers consisting of magnesium, cerium, lanthanum, and yttrium, and / or (4) a group of carbide-forming agents consisting of vanadium, titanium, tungsten, molybdenum, and niobium, and / or (5) a corrosion-resistant modifier consisting of chromium, nickel, molybdenum, silicon, aluminum, titanium, niobium, and phosphorus.

7. The laminated metal casting system according to any one of claims 1 to 6, wherein the molten metal is composed of an iron alloy and the minimum volume is at least 2 cubic centimeters.

8. The laminated metal casting system according to any one of claims 1 to 6, wherein the molten metal is composed of an iron alloy, and the minimum volume has a cooling rate of 2°C / second or less when cooled from its melting temperature.

9. The laminated metal casting system according to any one of claims 1 to 8, wherein the powder introduction unit comprises a supply nozzle configured to output the casting property modifying powder at a powder delivery angle and standoff distance to the molten zone, the molten zone having a molten zone boundary, and the powder delivery angle and standoff distance are pre-selected to ensure that the spot size of the delivered input amount of the accumulated amount on the molten zone is within the molten zone boundary.

10. The laminated metal casting system according to claim 9, wherein the powder nozzle is configured to maintain a powder spot size in the range of 2 to 50 mm in diameter with a powder nozzle standoff distance of 12 to 150 mm and a delivery angle in the range of 15 to 75°.

11. The laminated metal casting system according to any one of claims 1 to 10, wherein the powder introduction unit includes a feeder for introducing one or more amounts of the at least one casting property modifying powder.

12. The aforementioned feeder, - A powder reservoir for containing the casting property modification powder, - An input mechanism configured to release a predetermined amount of powder from the powder reservoir, - An inspection volume for collecting the amount of powder released before delivery to the melting zone, - A delivery system, comprising the laminated metal casting system according to claim 11.

13. The laminated metal casting system according to claim 12, wherein the input mechanism is configured to provide a powder input amount in the range of 1 microgram to 10 grams per input.

14. The laminated metal casting system according to claim 12, wherein the delivery system is a pressurized gas delivery system, and the feeder further includes a pressurized gas supply operably connected to the inspection volume for propelling the collected amount of powder toward the melting zone.

15. The laminated metal casting system according to any one of claims 9 to 14, wherein the feeder comprises a plurality of powder reservoirs, each containing a different casting property modifying powder, and the feed mechanism is configured to selectively release a predetermined amount from one or more of the powder reservoirs according to desired casting properties.

16. The system further comprises a molten metal depositor, the surface melter, and a controller operably connected to the powder introduction unit, wherein the controller A layered metal casting system according to any one of claims 1 to 15, wherein the molten metal depositor, the surface melter, and the powder introduction unit are configured to maintain a predetermined minimum volume of the molten zone in a molten state for at least a minimum duration sufficient to cause a desired casting property modification process in the minimum volume of the molten material.

17. The laminated metal casting system according to claim 16, wherein the minimum duration is sufficient to allow the allocated amount of the casting property modifying material to be completely melted and homogenized in the molten zone.

18. The laminated metal casting system according to claim 16, wherein the molten metal is composed of an iron alloy and the minimum duration is at least 1 second.

19. The laminated metal casting system according to any one of claims 16 to 18, wherein the controller is further configured to adjust the depositor and the surface melter so that when dropping and discharging, the molten metal droplets and the melting zone are maintained within a predetermined temperature difference not exceeding 100°C, while dropping the molten metal into the melting zone.

20. The laminated metal casting system according to any one of claims 16 to 19, wherein the allocated amount of the casting property modifying material is adjusted based on a predetermined fading rate of the casting property modifying powder during remelting.

21. The laminated metal casting system according to any one of claims 16 to 20, wherein the depositor deposits a first volume of molten metal by discharging droplets of molten metal in the form of (1) discrete droplets, (2) continuous dripping, or (3) continuous flow.

22. A multilayer metal casting system according to any one of claims 16 to 21, further comprising at least one temperature sensor for sensing the temperature of at least the melting zone, the at least one temperature sensor communicating data with the controller, and the controller being further configured to adjust the melter, metal depositor, and powder introduction unit based on temperature data received from the at least one temperature sensor.

23. The aforementioned controller In a continuous scanning mode, the metal processing assembly moves continuously along the processing path while maintaining a dynamic dissolution zone, The metalworking assembly is configured to implement a discrete scanning mode in which separate work areas are processed sequentially, The laminated metal casting system according to claim 22, wherein the controller selects the scanning mode based on at least one of the geometric shape of the part, thermal requirements, or material properties.

24. The aforementioned controller - To adjust scanning parameters in response to real-time thermal feedback, - To maintain a minimum melting zone volume specific to each scanning mode, - The timing of powder introduction is adjusted according to the selected scanning mode, and - The laminated metal casting system according to claim 23, further configured to manage thermal conditions at the boundary between adjacent work areas.

25. A laminated metal casting system according to any one of claims 16 to 24, wherein the controller is further operably connected to a mold builder, the controller is further configured to control the mold builder to construct the mold in progress, and the controller is further configured to adjust the mold builder to construct the current mold area of ​​the current production layer on the casting in progress before processing the current material area of ​​the current production layer.

26. The laminated metal casting system according to any one of claims 1 to 25, further comprising an inert environment unit, wherein at least a portion of the depositor, surface melter, and powder introduction unit adjacent to the molten zone and the free-fall molten metal is maintained in an inert environment.

27. The laminated metal casting system according to any one of claims 1 to 25, further comprising an inert environment unit, wherein the depositor, surface melter, powder introduction unit, and inert environment unit are physically connected and arranged as a single processing assembly movable over the upper surface of the casting in progress.

28. The laminated metal casting system according to claim 27, wherein the depositor is rotatable around the supply shaft of the integrated processing assembly and comprises a metal rod capable of lifting the supply shaft up and down, the surface melter comprises an induction heating unit having a planar closed coil with an opening positioned concentrically with the supply shaft, the inert environment unit is positioned around the induction heating unit, and the powder introduction unit has a supply nozzle positioned close to the depositor, and molten metal and the casting property modifying powder free-falling from the depositor are supplied to the molten zone through the opening.

29. A multilayer metal casting system according to any one of claims 16 to 28, further comprising a motion unit, wherein the controller is further configured to control the motion unit to provide relative movement of at least the depositor, the surface melter, and the powder introduction unit over the upper surface of the casting in progress.

30. The laminated metal casting system according to any one of claims 1 to 29, wherein the surface melter is further configured to provide heat to the molten zone after the first volume and the second volume have been accumulated, thereby influencing the cooling rate of the molten zone from its melting temperature.

31. The laminated metal casting system according to any one of claims 1 to 29, wherein the surface melter is further configured to provide heat to the molten zone after the first volume and the second volume have been accumulated, thereby maintaining the molten zone in a molten state for a predetermined duration.

32. A laminated metal casting system according to any one of claims 1 to 31, wherein for each production layer, the second volume of free-falling molten metal corresponds to the height of the current object region and the geometric shape of the inner wall of the mold region.

33. A laminated metal casting system according to any one of claims 1 to 32, wherein for each production layer, the first volume for remelting is calculated based on a predetermined cross-sectional area defined by a predetermined height of the casting in progress and the geometric shape of the inner wall of the mold in progress corresponding to the predetermined height of the casting in progress.

34. The laminated metal casting system according to claim 33, wherein the predefined height of the casting in progress is equal to one of the group consisting of (1) half the height of the object region, (2) the height of the object region, (3) twice the height of the object region, (4) three times the height of the object region, and (5) four times the height of the object region.

35. A multilayer metal casting system according to any one of claims 16 to 34, wherein the controller is configured to (1) determine the relative motion path of the depositor and surface melter over the upper surface of the casting in progress, thereby setting up the accumulation plan for the first and second volumes, and (2) determine one or more powder introduction sites along the motion path, such that when metallurgical modification powder is delivered to one of the powder introduction sites, at least the minimum volume is accumulated in each melting zone.

36. The laminated metal casting system according to any one of claims 31 to 35, wherein the height of the current object region is in the range of 2 mm to 50 mm.

37. The laminated metal casting system according to any one of claims 32 to 36, wherein the predefined height of the ongoing casting for remelting is in the range of 0.5 mm to 200 mm.

38. The laminated metal casting system according to any one of claims 16 to 37, wherein the controller is further configured to influence the cooling rate of a predetermined minimum volume when cooling from its melting temperature by setting one or more of (1) the first volume, (2) the second volume, (3) the deposition rate of the depositor, and (4) the melting rate of the melter.

39. A multilayer metal casting system for casting a metal object by producing a stack of production layers having mold regions and object regions, wherein the mold regions constitute a mold in progress, and the object regions constitute a casting in progress held within the mold in progress, and the multilayer metal casting system In the casting in progress, a surface melting vessel for melting a first volume of previously solidified metal, A metal depositor for dropping a second volume of molten metal into a first volume, wherein the first and second volumes accumulate within a molten zone of at least a minimum volume of the molten material; A powder introduction unit for delivering an allocated amount of at least one casting property modification powder, It includes an inert environment unit, The depositor, surface melter, powder introduction unit, and inert environment unit are physically connected and arranged as a single, movable processing assembly across the upper surface of the casting in progress. The depositor is rotatable around the supply shaft of the integrated processing assembly and includes a metal rod capable of lifting the supply shaft up and down; the surface melter includes an induction heating unit having a planar closed coil with an opening positioned concentrically with the supply shaft; the inert environment unit is positioned around the induction heating unit; the powder introduction unit has an off-axis supply nozzle positioned close to the depositor; and molten metal and the casting property modification powder, free-falling from the depositor, are supplied to the melting zone through the opening. and A controller operably connected to the molten metal depositor, the surface melter, and the powder introduction unit, A layered metal casting system for casting a metal object, comprising a controller configured to adjust the molten metal depositor, the surface melter, and the powder introduction unit to maintain the minimum volume of the molten zone in a molten state for at least a minimum duration sufficient to cause a desired casting property modification process in the minimum volume of the molten material.

40. A multilayer metal casting method for producing a metal object by generating a stack of production layers having mold regions and object regions, wherein the mold regions constitute a mold in progress, and the object regions constitute a casting in progress held within the mold in progress, and the method provides for each production layer: Iteratively, this includes constructing a template region of the current production layer on top of the production layer stack and processing the object region of the current production layer, Processing the object region of the current production layer, - In the casting in progress, a first volume of previously solidified metal is melted, and a second volume of molten metal is dropped into the first volume. - To provide an allocated amount of at least one casting property modification powder to the molten zone, -Optionally, maintain the molten zone in a molten state for a predetermined minimum duration, - This includes maintaining the molten zone in an inert environment while it is in a molten state, A multilayer metal casting method for producing a metallic object, wherein the first volume and the second volume are accumulated within a molten zone of at least the minimum volume of molten material required for the casting property modification process.

41. The method for multilayer metal casting according to claim 38, wherein the casting property modification powder includes a chemical modification material and / or a metallurgical modification material.

42. The method for multilayer metal casting according to claim 38 or 39, wherein the casting property modification process includes at least one of: (1) controlled graphite nucleation and growth to achieve a predetermined graphite morphology and / or distribution; (2) controlled phase transformation to result in a predetermined phase ratio; (3) in-situ chemical composition modification to achieve predetermined local material properties; (4) grain refinement to result in enhanced mechanical properties; (5) precipitation hardening; or (6) a controlled solidification process to result in a predetermined dendrite arm spacing.

43. The method for layered metal casting according to any one of claims 38 to 40, wherein the casting property modification process is controlled by one or more of the following: (1) maintaining the minimum volume at a predetermined temperature within a specific range for a predetermined residence time; and (2) maintaining a predetermined temperature gradient over the minimum volume.

44. The method for casting a laminated metal according to claim 38, wherein the molten metal is a cast iron alloy, and the at least one powder material is selected from the group consisting of (1) grain refiners comprising titanium alloys, zirconium alloys, and niobium alloys, and / or (2) inoculants comprising ferrosilicon, aluminum, silicone carbide, calcium, strontium, cerium, sodium, barium, and rare earth elements, and / or (3) deoxidizers comprising aluminum, silicon, manganese, and calcium, and / or (4) microstructure modifiers comprising magnesium, cerium, lanthanum, and yttrium, and / or (5) carbide forming agents comprising vanadium, titanium, tellurium, tungsten, and molybdenum.

45. The method for casting a laminated metal according to claim 38, wherein the molten metal is steel and / or a steel alloy, and the at least one powder material is selected from (1) a group of grain refiners consisting of aluminum alloys, titanium alloys, zirconium alloys, and niobium alloys, and / or (2) a group of oxygen scavengers consisting of aluminum, silicon, manganese, and calcium, and / or (3) a group of microstructure modifiers consisting of magnesium, cerium, lanthanum, and yttrium, and / or (4) a group of carbide forming agents consisting of vanadium, titanium, tungsten, molybdenum, and niobium, and / or (5) a corrosion resistance modifier consisting of chromium, nickel, molybdenum, silicon, aluminum, titanium, niobium, and phosphorus.

46. The laminated metal casting method according to any one of claims 38 to 43, wherein the molten metal is composed of an iron alloy and the minimum volume is at least 2 cubic centimeters.

47. The laminated metal casting method according to any one of claims 38 to 43, wherein the molten metal is composed of an iron alloy, and the minimum volume has a cooling rate of 2°C / second or less when cooled from its melting temperature.

48. The laminated metal casting method according to any one of claims 38 to 45, wherein the predetermined minimum duration is sufficient for the allocated amount to cause a desired casting property modification process in the minimum volume of the molten material.

49. The laminated metal casting method according to any one of claims 38 to 45, wherein the predetermined minimum duration is sufficient to allow the allocated amount of the casting property modification material in the molten zone to be completely dissolved and homogenized.

50. The method for casting laminated metal according to any one of claims 38 to 45, wherein the molten metal is composed of an iron alloy and the minimum duration is at least 1 second.

51. The method for casting laminated metal according to any one of claims 38 to 48, further comprising maintaining the molten metal droplet and the molten zone within a predetermined temperature difference not exceeding 100°C during the drop discharge.

52. The laminated metal casting method according to any one of claims 38 to 49, further comprising sensing the temperature of the upper surface of the ongoing casting after metal treatment of the current production layer, and proceeding to the next current production layer after the temperature of the upper surface of the ongoing casting reaches a predetermined value.

53. A method for layered metal casting according to any one of claims 38 to 50, wherein the provision includes outputting the casting property modifying powder at a powder delivery angle and standoff distance to the molten zone to ensure that the spot size of the allocated amount of provided input on the molten zone is within the boundary of the molten zone.

54. The laminated metal casting method according to any one of claims 38 to 51, wherein the allocated amount of the casting property modifying material is adjusted based on a predetermined fading rate of the casting property modifying powder during remelting.

55. The method for casting laminated metal according to any one of claims 38 to 52, wherein the dropping is in the form of (1) discrete droplets, (2) continuous dropping, or (3) continuous flow.

56. Processing the aforementioned object region - A continuous scanning pattern in which the work area moves dynamically with the processing assembly, or - This includes implementing at least one of a discrete scanning pattern that utilizes separate static work regions having defined boundaries, The laminated metal casting method according to any one of claims 38 to 52, wherein each scanning pattern maintains the molten zone at or above the minimum volume.

57. The aforementioned continuous scanning pattern is - Gradually moving the melting zone with continuous overlap between adjacent work areas, - Synchronizing metal deposition, surface heating, and powder delivery during transit, - Maintaining the molten zone volume by adjusting the heat input and metal addition, - A method for casting laminated metal according to claim 54, comprising operating at at least one of a constant or changing speed based on local thermal conditions.

58. The discrete scanning pattern is, - Sequentially processing separate work areas with defined boundaries, - Before moving to an adjacent area, complete the metal deposition, surface heating, and powder delivery in each work area. - Maintain a static melt zone for a predetermined residence time, - A method for casting laminated metal according to claim 54, comprising individually controlling the process parameters of each work area.

59. A method for producing a final casting by assigning an allocated amount of at least one casting property modification powder to a molten zone in a casting in progress while producing the object region of the current production layer of a production layer stack by a metalworking assembly, wherein the production layer has a mold region and an object region, the mold region constitutes a mold in progress, the object region constitutes a casting in progress held within the mold in progress, and the molten zone consists of a first volume of molten, previously solidified metal and a second volume of newly added molten metal in the casting in progress, and the method is The amount of the powder allocated to the current production layer is determined based on at least the following data items: (1) Desired target properties in the final casting, and at least one casting property modifying powder used, (2) Volume of the object region, (3) The volume of metal that was solidified before being remelted, and (4) Operating parameters of the metal processing assembly, The number and location of powder introduction points, and the allocation of powder to specific molten zones generated within the current production layer, are determined by optimizing the following synchronization: (1) Melting zone accumulation time, (2) Powder introduction delay time, and (3) A method comprising optionally maintaining the values ​​of the operating parameters of the metalworking assembly within an acceptable range.

60. The method according to claim 54, wherein the data item of the at least one casting property modification powder used includes fading characteristics of the at least one casting property modification powder under reheating and remelting.

61. The method according to claim 54 or 55, wherein the data items of the operating parameters of the metal processing assembly include data relating to at least the processing path, the metal processing assembly speed, the metal deposition rate, and the melter current supply parameters.

62. The method according to any one of claims 54 to 57, wherein the operating parameters of the metal processing assembly include the speed of the metal processing assembly, the working distance of the metal processing assembly over the current production layer, the metal deposition rate, the surface heater current supply, and the source heater current supply.

Images