Reinforced shaping method of photocured 3D printed ceramic cores

Abstract

The application relates to a reinforcing forming method of a photocured 3D printing ceramic core, which comprises the following steps: adding an outer frame model to the periphery of a three-dimensional model of the ceramic core, connecting the outer frame model and the side wall of the three-dimensional model through a plurality of connecting column models, and constructing an integrated reinforcing model; adding printing support to the reinforcing model; slicing the reinforcing model after the support is added, to generate slicing data required for photocured 3D printing; adopting ceramic slurry, photocured 3D printing according to the slicing data, integrally forming the ceramic core, the outer frame and the connecting column, and obtaining a green body of the ceramic core; removing the outer frame and the connecting column in the green body, and performing cleaning, degreasing and sintering treatment on the ceramic core. The outer frame model and the uniformly distributed connecting column model are added to the periphery of the three-dimensional model of the ceramic core, the rigidity of the green body is enhanced, the stress is uniform during the pressing process, defects caused by swinging of the green body are avoided, and the quality is effectively improved.

Description

Technical Field

[0001] This application relates to the field of 3D printing technology, and in particular to a method for reinforcing and forming a photopolymer 3D printed ceramic core. Background Technology

[0002] With the rapid development of industries such as aerospace, medical, and semiconductors, the demand for ceramic parts with complex three-dimensional structures is becoming increasingly urgent. In the process of preparing ceramic cores using photopolymer 3D printing technology, the surface quality and dimensional accuracy of the printing process have a decisive impact on the performance of the final sintered ceramic core.

[0003] In related technologies, high-solids-content ceramic slurries are typically used for printing to obtain high-density sintered bodies. However, the unglazed ceramic cores printed with such high-solids-content slurries tend to be soft and lack structural strength. Furthermore, because some ceramic core products are designed with thin-walled structures and uneven wall thickness, the already formed unglazed portion experiences uneven stress during the repeated pressing process on the printing platform. This can cause the unglazed portion to wobble after printing to a certain height.

[0004] In summary, the above printing methods suffer from defects such as misalignment, deformation, ghosting, and severe layering caused by the oscillation of the blank, which affect the quality of the final product. Summary of the Invention

[0005] Therefore, it is necessary to provide a reinforcement forming method for photopolymer 3D printed ceramic cores to address the problems of defects such as misalignment and deformation of molded parts in existing ceramic core printing methods, which affect product quality.

[0006] A method for reinforcing and forming a photopolymerizable 3D printed ceramic core, comprising:

[0007] An outer frame model is added around the three-dimensional model of the ceramic core, and the outer frame model is connected to the side wall of the three-dimensional model through multiple connecting column models to construct an integrated reinforced model.

[0008] Add printing support to the reinforced model;

[0009] The reinforced model with added support is sliced ​​to generate the slice data required for photopolymerization printing;

[0010] Using ceramic slurry, photopolymerization 3D printing is performed based on the slice data to integrally form the ceramic core, outer frame, and connecting pillars, thus obtaining the unglazed ceramic core.

[0011] Remove the outer frame and connecting pillars from the green blank, and clean, degrease and sinter the ceramic core.

[0012] In one embodiment, the connection point between the connecting column model and the sidewall of the three-dimensional model is located 40mm above the height of the sidewall of the three-dimensional model.

[0013] In one embodiment, the connecting column models are arranged at 20mm intervals on the sidewalls of the three-dimensional model.

[0014] In one embodiment, the connecting column model is symmetrically arranged on two opposite sides of the three-dimensional model.

[0015] In one embodiment, at least two of the connecting column models are provided on each side of the three-dimensional model.

[0016] In one embodiment, the outer frame model is a square or annular shape.

[0017] In one embodiment, the step of adding printing supports to the reinforced model includes: uniformly adding support models to the 3D model, the connecting column model, and the outer frame model.

[0018] In one embodiment, the step of generating the slice data required for photopolymerization printing includes: performing bitmap processing on the slice data to generate slice projection image data.

[0019] In one embodiment, the unglazed ceramic core is separated from the printing platform by machining.

[0020] In one embodiment, the ceramic slurry is a silicon-based ceramic slurry with a solid content greater than 65 vol%.

[0021] The above-mentioned reinforcement forming method for photopolymer 3D printed ceramic cores enhances the rigidity of the blank by adding an outer frame model and uniformly distributed connecting column models around the three-dimensional model of the ceramic core. This ensures that the blank is subjected to uniform force during the pressing process, avoids defects caused by blank swaying, and effectively improves the quality. Attached Figure Description

[0022] Figure 1 This is a schematic flowchart of a reinforcement molding method according to an embodiment of this application. Detailed Implementation

[0023] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0024] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0025] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0028] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0029] See Figure 1 , Figure 1 A schematic flowchart of a reinforcement molding method according to an embodiment of this application is shown.

[0030] An embodiment of this application provides a method for reinforcing and forming a photopolymerizable 3D printed ceramic core, comprising the following steps:

[0031] Step S1: Add an outer frame model around the three-dimensional model of the ceramic core, and connect the outer frame model to the side wall of the three-dimensional model through multiple connecting column models to construct an integrated reinforced model;

[0032] Step S2: Add printing supports to the reinforced model;

[0033] Step S3: Slice the reinforced model after adding support to generate the slice data required for photopolymerization printing;

[0034] Step S4: Using ceramic slurry, perform photopolymerization 3D printing according to the slice data to integrally form the ceramic core, outer frame and connecting column, and obtain the ceramic core blank;

[0035] Step S5: Remove the outer frame and connecting pillars from the green blank, and clean, degrease and sinter the ceramic core.

[0036] First, a three-dimensional model of the ceramic core was designed using 3D modeling software. This 3D model has a complex thin-walled structure with uneven wall thickness.

[0037] Subsequently, the 3D model of the ceramic core is imported into the pre-processing software for photopolymer 3D printing. The placement angle and position of the 3D model of the ceramic core are adjusted to optimize the printing process, reduce the need for supports, and ensure dimensional accuracy.

[0038] A rectangular outer frame model is constructed 5mm around the perimeter of the 3D model of the ceramic core. The bottom surface of this rectangular frame model is at the same level as the bottom surface of the ceramic core model, and its top surface is higher than the highest point of the 3D model of the ceramic core.

[0039] Then, multiple cylindrical connecting column models are constructed. Specifically, in the thin-walled area of ​​the ceramic core's 3D model where the height reaches more than 40mm, multiple cylindrical connecting column models are evenly added to the front and back sides of the model. The two ends of the connecting column models are fixedly connected to the side walls of the ceramic core's 3D model and the inner walls of the outer square frame model, respectively, forming an integrated reinforced model that includes the ceramic core, the outer frame model, and the connecting column models.

[0040] Further add the support structure required for printing to the reinforced model obtained in step S1. In this step, small dot-shaped or line-shaped supports need to be added to the bottom and overhanging parts of the 3D model of the ceramic core itself, all connecting column models, and the outer square model to ensure that the entire reinforced structure can be firmly attached to the printing platform at the start of printing, preventing it from falling off due to insufficient adhesion during the printing process.

[0041] Import the reinforced model with added support into the slicing software, set the layer thickness, and perform slicing. Then, import the printing process parameters, such as exposure time, bottom layer exposure time, and lift-off speed, and perform bitmap (BP) processing on the slice data to generate slice projection image data that the printer can recognize, such as .png format files.

[0042] In the photopolymer 3D printing process, a silicon-based ceramic slurry with a solid content greater than 65 vol% is prepared. This slurry consists of silica powder, photosensitive resin, dispersant, and photoinitiator, and is thoroughly mixed and degassed using a mixer. The processed slice projection data is imported into the photopolymer 3D printing equipment. The ceramic slurry is poured into the resin tank of the equipment. The equipment is started, and layer-by-layer exposure printing is performed according to preset parameters. During the printing process, the ceramic core, all connecting pillars, and the surrounding frame are integrally formed through the layer-by-layer curing of the slurry, forming a complete ceramic core blank.

[0043] After printing, use a scraper or similar tool to separate the entire preform structure from the printing platform. Remove the outer frame and connecting pillars from the ceramic core body, and remove the small printing supports. Immerse the preform of the ceramic core, after removing the reinforcing structure, in an organic solvent, such as anhydrous ethanol, for ultrasonic cleaning to remove any remaining uncured paste from the surface.

[0044] The cleaned green body is placed in a degreasing furnace for thermal degreasing to remove organic components. Subsequently, the degreased green body is transferred to a high-temperature sintering furnace for densification under a set atmosphere and temperature profile, ultimately obtaining the finished ceramic core.

[0045] By using the above-mentioned reinforcement and forming method, when printing the high model, the outer frame and evenly distributed connecting columns enhance the overall rigidity of the relatively soft blank and make it uniformly stressed during the pressing process. This avoids the swaying of the ceramic core blank during the printing process, ensuring that the ceramic core product is free from defects such as misalignment, deformation, and ghosting, and effectively improving the product qualification rate and quality.

[0046] In one embodiment, the connection point between the connecting column model and the sidewall of the three-dimensional model is located 40mm above the height of the sidewall of the three-dimensional model.

[0047] Specifically, all connecting pillars are connected to the sidewalls of the ceramic core's 3D model at a height of 40mm or more. When the 3D model's printing height is less than 40mm, the green blank itself has sufficient stability to resist downward pressure; however, when the 3D model's printing height exceeds 40mm, the risk of the green blank swaying increases significantly. Therefore, setting connecting pillars from the 40mm height position of the 3D model can effectively provide preventative reinforcement before problems occur.

[0048] In one embodiment, the connecting column models are arranged at 20mm intervals on the sidewalls of the three-dimensional model.

[0049] Specifically, the connecting columns are spaced 20mm apart on the sidewalls of the 3D model. If the spacing is too large, there will be insufficient support points, which will not be able to suppress the local deformation of the thin-walled structure; if the spacing is too small, the connecting columns will be too dense, wasting materials, increasing the workload of post-processing, and may also pose risks due to local stress concentration or excessive curing heat.

[0050] In one embodiment, the connecting column model is symmetrically arranged on two opposite sides of the three-dimensional model.

[0051] Specifically, the connecting column model is set on two opposite sides of the three-dimensional model of the ceramic core, such as the front and rear sides, and is symmetrically distributed to ensure that the force on the three-dimensional model in the front-back and left-right directions is balanced during the pressing process of the printing platform, thereby avoiding tilting or torsional deformation caused by unilateral force.

[0052] In one embodiment, at least two of the connecting column models are provided on each side of the three-dimensional model.

[0053] Specifically, on each side of the 3D model that needs reinforcement, at least two connecting column models are set up to form a stable support line or support surface on one side, thereby effectively constraining the displacement and sway of that side in all directions.

[0054] In one embodiment, the outer frame model is rectangular.

[0055] Specifically, the outer frame model is a rectangular frame. This frame surrounds the 3D model of the ceramic core. The rectangular frame has a simple structure, is easy to create and modify in modeling software, and its straight edges facilitate the addition of support structures. The four right-angled structures of the rectangular frame provide stress points, and through cooperation with connecting columns, effectively limit the swaying of the 3D model of the ceramic core.

[0056] In one embodiment, the outer frame model is annular.

[0057] Specifically, the outer frame model is annular. This annular frame is concentrically positioned with the 3D model of the ceramic core. The annular frame has no stress concentration points and can evenly bear forces from all directions. When the outline of the ceramic core model is close to a circle, using an annular frame ensures that the lengths of the connecting columns remain consistent, resulting in a more uniform stress distribution, optimized force balance, and prevention of excessive local stress.

[0058] In one embodiment, step S2, which involves adding printed supports to the reinforced model, includes step S21: adding support models to the three-dimensional model, the connecting column model, and the outer frame model.

[0059] Specifically, support points with a certain contact diameter are added to the bottom edge of the outer frame model, or at the four corners, to ensure that it can be anchored on the printing platform.

[0060] At the root area where the connecting column model connects to the outer frame model or the 3D model of the ceramic core, small supports are added according to their overhang angle to enhance their molding stability.

[0061] Supports are added to the overhanging structures and deep grooves of the 3D model of the ceramic core. By adding support models, it is ensured that the composite structure of the ceramic core, connecting pillars, and outer frame adheres to the printing platform, and the outer frame and connecting pillars are prevented from falling off during the layer-by-layer printing process.

[0062] Furthermore, the support model can be either tree-like or point-like. For the outer frame, supports with slightly higher density and larger contact points can be used; for the connecting columns and ceramic core, smaller, easier-to-remove supports are used.

[0063] In one embodiment, step S3, which generates the slice data required for photopolymerization printing, includes step S31: performing bitmap processing on the slice data to generate slice projection image data.

[0064] Specifically, bitmap processing is performed on the slice data to generate slice projection image data. By generating projection image data, it is ensured that the structure of the ceramic core body can be accurately formed during the photopolymerization 3D printing process, and its outer frame structure and connected pillars can also be formed synchronously and integrally, thereby ensuring that the reinforced structure can enhance rigidity and ensure uniform stress distribution.

[0065] In one embodiment, the unglazed ceramic core is separated from the printing platform by machining.

[0066] Specifically, after the photopolymerization 3D printing process is completed, the printing platform holds the cured preform, which includes the ceramic core body, connecting pillars, outer frame structure, and all printing supports. The preform is then separated from the printing platform using mechanical methods, such as scrapers or chisels. For large or complex preforms, a multi-point, segmented cutting approach can be used to gradually separate them, ensuring uniform stress release.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for reinforcing and forming a photopolymerizable 3D printed ceramic core, characterized in that, include: An outer frame model is added around the 3D model of the ceramic core. The bottom surface of the outer frame model is at the same level as the bottom surface of the 3D model, and the top surface of the outer frame model is higher than the highest point of the 3D model. The outer frame model is connected to the side wall of the 3D model through multiple connecting pillar models. The two ends of the connecting pillar models are fixedly connected to the inner wall of the outer frame model and the side wall of the 3D model, respectively, to construct an integrated reinforced model. Adding printing support to the reinforced model includes: uniformly adding support models to the 3D model, connecting column model, and outer frame model; The reinforced model after adding support is sliced ​​to generate slice data required for photopolymerization printing, including: bitmap processing of the slice data to generate slice projection image data; Using ceramic slurry, photopolymerization 3D printing is performed based on the slice data to integrally form the ceramic core, outer frame, and connecting pillars, thus obtaining the unglazed ceramic core. Remove the solidified outer frame and connecting pillars from the green blank, and clean, degrease and sinter the ceramic core.

2. The method for reinforcing and forming a photopolymerizable 3D printed ceramic core according to claim 1, characterized in that, The connection point between the connecting column model and the side wall of the three-dimensional model is located 40mm above the height of the side wall of the three-dimensional model.

3. The method for reinforcing and forming a photopolymerizable 3D printed ceramic core according to claim 2, characterized in that, The connecting column models are arranged at 20mm intervals on the sidewalls of the three-dimensional model.

4. The method for reinforcing and forming a photopolymerizable 3D printed ceramic core according to claim 2, characterized in that, The connecting column model is symmetrically arranged on two opposite sides of the three-dimensional model.

5. The method for reinforcing and forming a photopolymerizable 3D printed ceramic core according to claim 4, characterized in that, At least two of the connecting column models are provided on each side of the three-dimensional model.

6. The method for reinforcing and forming a photopolymerizable 3D printed ceramic core according to claim 1, characterized in that, The outer frame model is either square or circular.

7. The method for reinforcing and forming a photopolymerizable 3D printed ceramic core according to claim 1, characterized in that, The unglazed ceramic core is separated from the printing platform by mechanical processing.

8. The method for reinforcing and forming a photopolymerizable 3D printed ceramic core according to claim 1, characterized in that, The ceramic slurry is a silicon-based ceramic slurry with a solid content greater than 65 vol%.

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