Multi-material sand mold and ceramic hot-cold integrated conformal manufacturing method and apparatus

Abstract

This invention relates to a method and apparatus for the integrated hot and cold conformal manufacturing of multi-material sand molds and ceramics, comprising a freely height-adjustable printing platform; a sand-laying guide rail fixed on a printing support; a nozzle guide rail moving along the sand-laying guide rail; a sand-laying groove fixed on the nozzle guide rail; and ceramic powder nozzles and binder nozzles moving along the nozzle guide rail. Utilizing additive manufacturing principles, a casting sand mold with a hollowed-out and conformal ceramic pipe structure is produced, reducing the weight of the sand mold, reducing material usage, increasing the venting performance of the sand mold, and enhancing the cooling capacity of the metal. During the molten metal pouring process, high-temperature media such as water, oil, and air are supplied to the conformal ceramic pipes, increasing the temperature of the mold, reducing the heat conduction and heat radiation of the molten metal, and improving the filling capacity of the molten metal.

Description

Technical Field

[0001] This invention relates to the field of sand mold additive manufacturing, and in particular to a method and apparatus for the integrated hot and cold conformal manufacturing of multi-material sand molds and ceramics. Background Technology

[0002] The ability of molten metal to fill the mold cavity during the casting process, resulting in a casting with a complete shape and clear outline, is called filling capacity. Poor filling capacity can lead to defects such as incomplete filling and cold shuts. Currently, the casting industry mostly improves filling capacity by controlling the temperature of the molten metal, a relatively simplistic approach. New methods need to be developed to further enhance filling capacity. After the molten metal has filled the mold, it slowly cools to room temperature. The cooling process of the casting within the mold plays a crucial role in its quality. Slow cooling, especially for larger castings, can lead to defects such as coarse grains, segregation, cracks, and difficulty in feeding, resulting in poor mechanical properties. In actual production, finer grains are typically obtained by adding trace elements or increasing the cooling rate during solidification, thereby improving the strength, plasticity, toughness, and other mechanical properties of the casting and producing high-quality castings. Currently, the foundry industry typically uses materials with strong heat storage capacity, such as chilled iron, chromite sand, and metal molds, to enhance cooling through heat storage and dissipation. However, this cannot fully meet the purpose of enhanced cooling and increases production costs and operational difficulties. Summary of the Invention

[0003] To address the aforementioned issues, this invention discloses a multi-material sand mold and ceramic integrated hot and cold conformal manufacturing method and apparatus, which improves the mold filling and enhanced cooling capacity during the casting process.

[0004] A multi-material sand mold and ceramic hot-cold integrated conformal manufacturing device includes a freely lifting printing platform; a sand-laying guide rail fixed on the printing bracket; a nozzle guide rail moving along the sand-laying guide rail; a sand-laying groove fixed on the nozzle guide rail; and ceramic powder nozzles and binder nozzles moving along the nozzle guide rail.

[0005] Furthermore, the printing platform, sand-laying guide rail, nozzle guide rail, sand-laying trough, ceramic powder nozzle, and adhesive nozzle are all in a horizontal position.

[0006] Furthermore, a heating device is installed at the bottom of the printing platform, and a fan is provided to blow hot air out through small holes in the printing platform, so that the adhesive can solidify and bond during printing. After printing, there is no need to wait for solidification time, and the deformation caused by subsequent heat treatment is reduced.

[0007] Furthermore, the printing platform can be freely raised and lowered to meet the needs of different printing layer thicknesses.

[0008] Furthermore, the sand-laying trough has both sand-laying and sand-scraping functions. It uses a brush sand scraper to lay sand first and then scrape sand, ensuring that the printed sand layer is flat and dense. The bottom of the sand-laying port can be controlled to open and close. When sand-laying is not needed, the sand-laying port is closed.

[0009] Furthermore, the ceramic powder nozzle and the binder nozzle share a nozzle guide rail, and the translational movement on the nozzle guide rail and the translational movement of the nozzle guide rail on the sand-laying guide rail ensure that the ceramic powder nozzle and the binder nozzle cover any position on the printing platform.

[0010] Furthermore, the ceramic powder nozzle can be controlled to open and close via a cylinder, and also has a vibration-based powder-falling function to ensure the quality of ceramic powder placement. A cylinder is fixed to the outside of the ceramic powder nozzle, with its cylinder shaft connected to a connecting rod inside the nozzle. A sealing plate is located at the bottom of the connecting rod. The cylinder drives the internal connecting rod to open and close the nozzle when necessary. An ultrasonic transducer is integrated inside the ceramic powder nozzle, generating high-frequency vibrations that cause the ceramic powder to fall. The ceramic powder nozzle is conical; in its closed state, the nozzle performs a powder-scraping function, removing most of the powder from the inside of the conformal ceramic pipe.

[0011] This invention also provides a method for manufacturing multi-material sand molds and ceramic hot and cold integrated conformal molding, which is carried out according to the following steps:

[0012] Step 1: Design the three-dimensional model of the sand mold based on the geometric characteristics of the casting;

[0013] Step 2: The three-dimensional sand mold design is divided into sections for design and manufacturing. The cavity part retains the solid structure, while the rest is transformed into a hollow dot matrix structure.

[0014] Step 3: Merge the hollow dot matrix structure model with the cavity solid model;

[0015] Step 4: Design and add conformal ceramic pipe structures close to the solid structure in the hollow structure to form the final sand mold shape;

[0016] Step 5: Perform layered slicing on the conformal ceramic pipe section and the remaining section respectively, with a slice thickness of 0.1-0.5 mm;

[0017] Step 6: Control the ceramic powder nozzle to lay ceramic powder on the printing platform according to the layered slicing data of the conformal ceramic pipeline;

[0018] Step 7: Lay molding sand in the sand-laying trough and level it;

[0019] Step 8: The adhesive nozzle sprays adhesive according to the cut data of the conformal ceramic tube and the remaining parts;

[0020] Step 9: The ceramic powder nozzle cleans the internal powder material along the pipe path according to the cut data of the conformal ceramic pipe;

[0021] Step 10: Scrape the sand layer in the sand trough to remove the loose sand generated in step 9;

[0022] Step 11: Lower the printing platform to the slice thickness height, and repeat steps 6-10 until the sand mold is finally formed;

[0023] Step 12: Clean up the fallen sand and remove the sand mold.

[0024] Furthermore, in step 2, the thinnest wall thickness of the cavity should be greater than or equal to 5mm to ensure that the cavity has a certain strength. The hollow lattice structure can take various forms, including but not limited to those generated by lattices of regular tetrahedrons, regular hexahedrons, regular octahedrons, regular dodecahedrons, and irregular shapes, without limitation on the size of the lattice. The hollow lattice structure mainly serves to support the solid cavity, and can also reduce material usage, shorten manufacturing time, make mold making easier, and increase the permeability of the sand mold.

[0025] Furthermore, in step 4, the diameter of the conformal ceramic pipe can be variable. In areas with a larger casting wall thickness, the diameter of the conformal ceramic pipe can be increased to enhance the temperature control effect of the conformal ceramic pipe. The minimum wall thickness of the conformal ceramic pipe should be greater than or equal to 1 mm.

[0026] Furthermore, in steps 6 to 10, when any one of the ceramic powder nozzle, sand spreading trough, and adhesive nozzle is working, the other two components do not operate until the operating component and the nozzle guide rail have returned to the zero position, at which point the other component can operate.

[0027] Furthermore, in step 7, when spreading powder, the sand spreading trough can be adjusted according to the thickness of the slice, the size of the sand spreading opening, and the moving speed of the sand spreading trough to save material usage and improve forming efficiency.

[0028] Furthermore, in step 12, the floating sand inside the conformal ceramic pipe needs to be cleaned by slowly introducing circulating water after the sand mold is removed.

[0029] This invention utilizes inkjet 3D printing to create a hollowed-out sand mold with conformal ceramic tubing, improving the mold's venting capacity, reducing material usage, and increasing molding efficiency. During molten metal filling, high-temperature media such as water, oil, or air are introduced into the conformal ceramic tubing to raise the mold temperature. Furthermore, the hollowed-out sand mold's superior venting capacity significantly enhances the molten metal filling process. Once the molten metal filling is complete and the cooling phase begins, low-temperature media such as water, oil, air, dry ice, or liquid nitrogen are introduced into the conformal ceramic tubing to force-cool the casting, refining the grain structure, reducing crack defects, shortening mold-making time, and improving production efficiency. This invention provides a rapid manufacturing method and apparatus for hollow structure sand molds, which can improve the filling capacity and forced cooling capacity of molten metal, significantly reduce defects such as incomplete filling, cold shut, coarse grain structure, cracks, and difficulty in feeding in castings, improve the mechanical properties of castings, obtain high-quality castings, and the invention has a fast forming speed, high production efficiency, saves molding sand, and can form complex molds.

[0030] The beneficial effects of this invention are:

[0031] 1. The device of the present invention can form a hollow dot matrix structure sand mold with conformal ceramic pipes, realize multi-material composite molding, form quickly, save sand usage, shorten box making time, and improve production cycle.

[0032] 2. The sand mold produced by the method of the present invention has good air permeability, can realize mold temperature control, is more suitable for different casting and forming stages of casting, improves the filling capacity of molten metal, increases the cooling rate of casting, shortens the overall solidification time of casting, reduces component segregation in thick-walled parts of casting, improves casting grain size, reduces casting defects, significantly improves the dimensional and shape accuracy of casting, and obtains superior mechanical properties. Attached Figure Description

[0033] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0034] Figure 2 This is a side view of the structure of the present invention;

[0035] Figure 3 This is a side view of the sand spreader of the present invention;

[0036] Figure 4 This is an enlarged view of the ceramic powder nozzle of the present invention;

[0037] Figure 5 This is a cross-sectional view of the ceramic powder nozzle of the present invention;

[0038] Figure 6 This is a cross-sectional view of the ceramic powder nozzle of the present invention;

[0039] Figure 7This is a flowchart illustrating the implementation of the present invention;

[0040] Figure 8 This is a schematic diagram illustrating a specific example of the present invention.

[0041] List of reference numerals in the attached diagram:

[0042] 1-Printing platform, 2-Sand spreading guide rail, 3-Printer bracket, 4-Nozzle guide rail, 5-Sand spreading trough, 6-Ceramic powder nozzle, 7-Laser, 8-Irregular ceramic pipeline, 9-Hollow structure area, 10-Cavity solid area. Detailed Implementation

[0043] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0044] Figure 1-6 The image shown is a multi-material sand mold and ceramic hot and cold integrated conformal manufacturing device according to this embodiment; it mainly includes a printing platform 1, a sand spreading guide rail 2, a printer bracket 3, a nozzle guide rail 4, a sand spreading trough 5, a ceramic powder nozzle 6, and an adhesive nozzle 7.

[0045] The printer bracket 3, as the main structure of the device, supports and fixes other components and is the main factor limiting the printing range of the printing platform. Components such as the printing platform 1, sand-laying guide rail 2, nozzle guide rail 4, sand-laying trough 5, ceramic powder nozzle 6, and adhesive nozzle 7 must be kept horizontal to ensure printing accuracy.

[0046] The printing platform 1 can be freely raised and lowered according to the slice thickness to meet printing needs. A heating device and a fan are installed at the bottom of the printing platform 1, allowing hot air to be blown out through small holes in the platform. This accelerates the curing and bonding of the adhesive during printing, eliminating the need for curing time after printing and reducing deformation caused by subsequent heat treatment. The ceramic powder nozzle 6 lays ceramic powder on the printing platform 1 according to the slice data of the conformal ceramic tube. The sand-laying trough 5 lays a sand layer across the entire surface of the printing platform 1; the speed of the sand-laying trough and the opening size of the sand-laying opening vary depending on the slice thickness.

[0047] Adhesive nozzle 7 sprays adhesive evenly onto the conformal ceramic pipes and the areas where the sand mold needs to be formed, allowing the ceramic powder and molding sand to bond and form the desired shape. Ceramic powder nozzle 6 cleans the pipe sections of the conformal ceramic pipes to ensure unobstructed flow. After cleaning the conformal ceramic pipes, sand is scraped from the sand-laying trough 5 to ensure a clean sand layer.

[0048] like Figure 7 As shown, the specific implementation steps of the method of the present invention are as follows:

[0049] Step 1: Determine the dimensions of the sand mold based on the three-dimensional shape of the casting, and design the three-dimensional shape of the sand mold;

[0050] Step 2: Divide the designed three-dimensional sand mold into a cavity solid area 10 and a hollow structure area 9, ensuring that the thinnest wall thickness of the cavity should be greater than or equal to 5mm, and convert the hollow structure area into a hollow lattice structure generated by the crystal lattice.

[0051] Step 3: Merge the converted hollow dot matrix structure with the cavity solid model;

[0052] Step 4: Design and add conformal ceramic tubes (8 structures) close to the solid structure within the hollow structure. The wall thickness of the conformal ceramic tubes should be greater than or equal to 1mm to form the final sand mold shape. Example: Figure 4 As shown;

[0053] Step 5: Perform layered slicing on the 8 parts of the conformal ceramic pipe and the remaining part respectively. The slicing thickness can be selected from 0.1 to 0.5 mm depending on the complexity of the forming casting and other special structural requirements.

[0054] Step 6: Control the ceramic powder nozzle 6 to lay ceramic powder on the printing platform according to the layered slicing data of the conformal ceramic pipeline 8;

[0055] Step 7: Sand spreading trough 5: Lay molding sand in sand spreading trough 5 according to the set sand spreading opening size and sand spreading speed, and scrape it flat to form a sand layer in which ceramic powder and molding sand coexist.

[0056] Step 8: Adhesive nozzle 7 sprays adhesive according to the conformal ceramic pipe and other slice data, so that the ceramic powder and molding sand of the part to be formed are bonded together.

[0057] Step 9: Ceramic powder nozzle 6 cleans the internal ceramic powder along the pipe according to the cut data of the conformal ceramic pipe to ensure that the conformal ceramic pipe is unobstructed;

[0058] Step 10: Scrape the sand layer in sand trench 5 to remove the loose sand generated in step 9;

[0059] Step 11: Lower the slice thickness height on printing platform 1, and repeat steps 6 to 10 until the sand mold is finally formed;

[0060] Step 12: Clean up the fallen sand, remove the sand mold, and after the sand mold is completely bonded, slowly flow cleaning water into the conformal ceramic pipe 8 to clean the inside of the conformal ceramic pipe.

[0061] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A method for integrated conformal manufacturing of multi-material sand molds and ceramics for hot and cold heating, characterized in that, The device is prepared by a multi-material sand mold and ceramic hot and cold integrated conformal manufacturing process, including a printing platform (1), a sand-laying guide rail (2), and a printer bracket (3); the printing platform (1) is controlled by a lead screw and a servo motor to achieve free lifting and lowering; the sand-laying guide rail (2) consists of two parallel guide rails and is installed on the printer bracket (3); it also includes a printhead guide rail (4), a sand-laying groove (5), a ceramic powder printhead (6), and an adhesive printhead (7); the printhead guide rail (4) is controlled by two servo motors to move horizontally on the sand-laying guide rail (2); the sand-laying groove (5) is installed on the printhead guide rail (4) and moves with the printhead guide rail; the ceramic powder printhead (6) is installed on the printhead guide rail (4) and is driven by a servo motor to achieve horizontal movement; the adhesive printhead (7) is a piezoelectric inkjet printhead, installed on the printhead guide rail (4), and is driven by a servo motor to achieve horizontal movement; the specific steps include the following: Step 1: Design the three-dimensional model of the sand mold based on the geometric characteristics of the casting; Step 2: The three-dimensional model of the sand mold is designed and manufactured in sections. The part close to the casting retains the solid structure, while the rest is transformed into a hollow dot matrix structure. Step 3: Merge the hollow dot matrix structure model with the solid structure model that is close to the casting; Step 4: Design and add conformal ceramic pipe structures close to the solid structure in the hollow structure to form the final sand mold shape; Step 5: Perform layered slicing on the conformal ceramic pipe (8) and the remaining part respectively. The slicing thickness is adjustable from 0.1 to 0.5 mm. Step 6: Control the ceramic powder nozzle (6) to lay ceramic powder on the printing platform (1) according to the layered slicing data of the conformal ceramic pipeline (8); Step 7: Sand Laying Trench (5) Lay out molding sand and level it; Step 8: The adhesive nozzle (7) sprays adhesive according to the conformal ceramic pipe (8) and the remaining slice data; Step 9: Ceramic powder nozzle (6) cleans the internal powder material along the pipeline path according to the conformal ceramic pipeline slice data; Step 10: Sand trough (5) scrape the sand layer to remove the loose sand generated in step 9; Step 11: The printing platform (1) lowers the slice thickness height, and repeats steps 6 to 10 until the sand mold is finally formed; Step 12: Clean up the fallen sand and remove the sand mold.

2. The method for integrated conformal manufacturing of multi-material sand molds and ceramics with hot and cold processes according to claim 1, characterized in that, In step 2, the thinnest wall thickness of the solid structure close to the casting should be greater than or equal to 5mm. The hollow dot matrix structure has various forms, including regular tetrahedron, regular hexahedron, regular octahedron, regular dodecahedron, and irregular shapes.

3. The method for integrated conformal manufacturing of multi-material sand molds and ceramics with hot and cold heating as described in claim 1, characterized in that: In step 4, the diameter of the conformal ceramic pipe can be varied. The diameter of the conformal ceramic pipe is increased in the parts with larger casting wall thickness to increase the flow rate and flow of high / low temperature media, and enhance the temperature control effect of the conformal ceramic pipe. The minimum wall thickness of the conformal ceramic pipe is greater than or equal to 1 mm.

4. The method for integrated conformal manufacturing of multi-material sand molds and ceramics with hot and cold heating according to claim 1, characterized in that: In steps 6 to 10, when any one of the ceramic powder nozzle (6), sand spreading trough (5), and adhesive nozzle (7) is working, the other two parts do not move until the moving parts and nozzle guide rail (4) have returned to the zero position, then the other part can move.

5. The method for integrated conformal manufacturing of multi-material sand molds and ceramics with hot and cold processes according to claim 1, characterized in that: In step 7, when the sand spreading trough (5) spreads powder, it feeds back to the predetermined program according to the thickness of the slice, and adjusts the size of the sand spreading opening and the moving speed of the sand spreading trough by controlling the linkage mechanism through the servo motor.

6. The method for integrated conformal manufacturing of multi-material sand molds and ceramics with hot and cold processes according to claim 1, characterized in that: In step 12, after removing the sand mold, the floating sand inside the conformal ceramic pipe (8) can be cleaned by slowly introducing circulating water.

7. The method for integrated conformal manufacturing of multi-material sand molds and ceramics with hot and cold heating according to claim 1, characterized in that: The printing platform (1), sand-laying guide rail (2), nozzle guide rail (4), sand-laying trough (5), ceramic powder nozzle (6), and adhesive nozzle (7) are in a horizontal position to ensure forming accuracy; the sand-laying trough (5) is provided with a sand-scraping brush on the rear side of its sand-laying opening; the sand-laying opening is controlled by a servo motor to open and close the baffle, and when sand-laying is not required, the baffle closes the sand-laying opening.

8. The method for integrated conformal manufacturing of multi-material sand molds and ceramics with hot and cold processes according to claim 1, characterized in that: The bottom of the printing platform (1) is equipped with a heating device and a fan to blow hot air out through the small holes on the printing platform (1).

9. The method for integrated conformal manufacturing of multi-material sand molds and ceramics with hot and cold processes according to claim 1, characterized in that: A cylinder is fixed on the outside of the ceramic powder nozzle (6), wherein the cylinder shaft is connected to the connecting rod inside the ceramic powder nozzle (6), and a sealing plate is provided at the bottom of the connecting rod. The cylinder drives the internal connecting rod to open and close the nozzle, thereby realizing the opening and closing of the nozzle. An ultrasonic transducer is integrated inside the ceramic powder nozzle (6). The nozzle of the ceramic powder nozzle (6) is conical, and the closed state of the ceramic powder nozzle realizes the function of scraping powder.

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