Strengthening and forming method for photocuring 3D printing ceramic core

Abstract

The invention relates to a reinforcing and forming method for a photocuring 3D printing ceramic core, which comprises the following steps: additionally arranging an outer frame model on the periphery of a three-dimensional model of the ceramic core, and connecting the outer frame model with the side wall of the three-dimensional model through a plurality of connecting column models to construct an integrated reinforcing model; adding a printing support to the strengthened model; slicing the reinforced model added with the support to generate slice data required by photocuring printing; ceramic slurry is adopted, photo-curing 3D printing is conducted according to the slicing data, the ceramic core, the outer frame and the connecting columns are integrally formed, and a biscuit of the ceramic core is obtained; and the outer frame and the connecting columns in the biscuit are removed, and the ceramic core is subjected to cleaning, degreasing and sintering treatment. The outer frame model and the uniformly distributed connecting column models are additionally arranged on the periphery of the three-dimensional model of the ceramic core, so that the rigidity of a biscuit is enhanced, the biscuit is uniformly stressed in the pressing process, defects caused by swinging of the biscuit are avoided, and the quality is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of 3D printing, in particular to a reinforcing forming method for photocuring 3D printed ceramic cores. BACKGROUND

[0002] With the rapid development of aerospace, medical and semiconductor industries, the demand for ceramic parts with complex three-dimensional structures is increasingly urgent. In the process of preparing ceramic cores by photocuring 3D printing technology, the surface quality and dimensional accuracy of the printing forming link have a decisive influence on the performance of the ceramic cores sintered finally.

[0003] In related technologies, high solid content ceramic slurry is usually prepared for printing to obtain high density sintered bodies. However, the green body of the ceramic core printed by such high solid content slurry has the problem of soft texture and insufficient structural strength. At the same time, since some ceramic core products are designed with thin-walled structure and uneven wall thickness, the formed green body is unevenly stressed in the forming process of repeated pressing of the printing forming platform. When printing to a certain height, the green body will swing.

[0004] In summary, the above-mentioned printing method has the problem that the swing of the green body leads to defects such as misregistration, deformation, ghosting and serious layer lines of the finally formed parts, thereby affecting the product quality. SUMMARY

[0005] Therefore, it is necessary to provide a reinforcing forming method for photocuring 3D printed ceramic cores in view of the defects such as misregistration and deformation of the formed parts existing in the existing ceramic core printing method, which affects the product quality.

[0006] A reinforcing forming method for photocuring 3D printed ceramic cores, comprising:

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

[0008] Printing support is added to the reinforced model;

[0009] The reinforced model with the added support is sliced to generate slicing data required for photocuring 3D printing;

[0010] Ceramic slurry is used to perform photocuring 3D printing according to the slicing data, so that the ceramic core, the outer frame and the connecting column are integrally formed to obtain a green body of the ceramic core;

[0011] The outer frame and the connecting column in the green body are removed, and the ceramic core is cleaned, degreased and sintered.

[0012] In one embodiment, the connection column model is higher than the 40mm position of the three-dimensional model sidewall height.

[0013] In one embodiment, the connection column model is spaced at intervals of 20mm on the three-dimensional model sidewall.

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

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

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

[0017] In one embodiment, in the step of adding printing support to the reinforcement model, a support model is uniformly added to the three-dimensional model, connection column model and outer frame model.

[0018] In one embodiment, the step of generating slice data required for light-cured printing includes: bitmapping the slice data to generate slice projection picture data.

[0019] In one embodiment, the green body of the ceramic core is separated from the printing forming platform by mechanical processing.

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

[0021] The above-mentioned light-cured 3D printing ceramic core reinforcement forming method enhances the rigidity of the green body by adding an outer frame model and uniformly distributed connection column models to the periphery of the three-dimensional model of the ceramic core, so that the green body is uniformly stressed during the pressing process, avoiding defects caused by green body swinging, and effectively improving the quality. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The above-mentioned light-cured 3D printing ceramic core reinforcement forming method enhances the rigidity of the green body by adding an outer frame model and uniformly distributed connection column models to the periphery of the three-dimensional model of the ceramic core, so that the green body is uniformly stressed during the pressing process, avoiding defects caused by green body swinging, and effectively improving the quality. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below. In the following description, a large number of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0024] In the description of the present application, it should be understood that, if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0025] In addition, if there are terms such as "first", "second" appear, these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can include at least one of the features explicitly or implicitly. In the description of the present application, if the term "multiple" appears, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0026] In the present application, unless otherwise explicitly specified and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be interpreted broadly. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] In the present application, unless otherwise explicitly specified and limited, if there are similar descriptions such as "first feature on" or "under" the second feature, the meaning can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0028] It is to be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be an intervening element. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar expressions, if used, are used for explanation only and are not intended to be limiting.

[0029] Referring to Figure 1 , Figure 1 A flowchart of a reinforcing forming method in an embodiment of the present application is shown.

[0030] An embodiment of the present application provides a reinforcing forming method of a photocured 3D printed ceramic core, comprising the following steps:

[0031] Step S1, an outer frame model is added outside 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 a plurality of connecting column models, thereby constructing an integrated reinforcing model;

[0032] Step S2, printing support is added to the reinforcing model;

[0033] Step S3, the reinforcing model after adding the support is sliced to generate slice data required for photocured printing;

[0034] Step S4, ceramic slurry is used to perform photocured 3D printing according to the slice data, so that the ceramic core, the outer frame, and the connecting column are integrally formed, thereby obtaining a green body of the ceramic core;

[0035] Step S5, the outer frame and the connecting column in the green body are removed, and the ceramic core is cleaned, degreased, and sintered.

[0036] Firstly, a three-dimensional model of the ceramic core is designed by using a three-dimensional modeling software. The three-dimensional model has a complex thin-walled structure and uneven wall thickness.

[0037] Subsequently, the three-dimensional model of the ceramic core is imported into a pre-processing software of photocured 3D printing. The placement angle and position of the three-dimensional model of the ceramic core are adjusted to optimize the printing process, reduce the support, and ensure the accuracy of the size.

[0038] An outer frame model in the shape of a square frame is constructed at a distance of 5mm from the periphery of the three-dimensional model of the ceramic core. The bottom surface of the square frame model is at the same level as the bottom surface of the ceramic core model, and the top surface is higher than the highest point of the three-dimensional 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 printing 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 at 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 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. Add printing support to the reinforced model; The reinforced model with added support is sliced ​​to generate the slice data required for photopolymerization printing; 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 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 pillar 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 step of adding printing supports to the reinforced model includes: uniformly adding support models to the 3D model, connecting column model and outer frame model.

8. The method for reinforcing and forming a photopolymerizable 3D printed ceramic core according to claim 1, characterized in that, 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.

9. 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.

10. 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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