3D printing ceramic core with self-collapsing structure and preparation method of 3D printing ceramic core

Abstract

The invention discloses a 3D printing ceramic core of a self-collapsing structure and a preparation method of the 3D printing ceramic core, and belongs to the technical field of 3D printing ceramics. According to the 3D printing ceramic core, an internal locking structure is arranged in an overall structure of the ceramic core, the internal locking structure and a main body structure of the ceramic core are integrally formed, the main body structure of the ceramic core is composed of a plurality of forming units, the forming units provide structural strength for the ceramic core, and each forming unit is at least connected with one locking structure. The internal locking structure is connected with the main body structure of the mold core, so that the internal locking structure can be automatically damaged and collapsed after being triggered by a preset external force or a specific condition in a specific direction, a forming unit in the main body structure in the ceramic mold core is further driven to be collapsed, and the whole ceramic mold core can be collapsed in a mold cavity; the internal locking of the structure can enhance the overall strength of the core while effectively maintaining the structural stability of the ceramic core under the conditions of high temperature and high pressure.

Description

Technical Field

[0001] The present invention belongs to the technical field of 3D printing ceramics, and in particular relates to a 3D printing ceramic core with a self-collapsing structure and a preparation method thereof. Background Art

[0002] Ceramic cores are special ceramic products used to form complex and precise inner cavities in investment casting. They have a wide range of technical backgrounds and applications, especially in the manufacture of turbine blades for aircraft engines and gas turbines, because turbine blades require complex internal cooling structures that cannot be manufactured by traditional machining methods. Aircraft engines and gas turbines are the crystallization of high technology and have an important impact on the country's industrial technology level. As a key consumable in these engines, the development of ceramic core technology is of great significance to improving engine performance and promoting industrial upgrading. The development of ceramic core technology can not only promote the advancement of investment casting technology, but also provide technical support for the manufacture of key components such as aircraft engines and gas turbines. With the continuous advancement of new materials and molding technology, the application prospects of ceramic cores will be broader.

[0003] In the investment casting process, the matching of ceramic core performance and core removal is the most critical link, which directly affects the precision and yield of the casting. However, since the ceramic core needs to remain stable at a high temperature of 1500-1600℃, in order to ensure high temperature strength, it is generally chosen to lose a part of the core removal performance. However, poor core removal performance will make it difficult to completely remove the ceramic core from the casting after the casting cools, thereby affecting the internal structure accuracy of the casting, and prolonging the production cycle, increasing the difficulty and cost of operation during the core removal process, thereby reducing the overall production efficiency and economic benefits. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a 3D printed ceramic core with a self-collapsing structure and a preparation method thereof, so as to solve the technical problem that the ceramic core is difficult to remove in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A 3D printed ceramic core with a self-collapsing structure, wherein the internal support structure in the ceramic core is a metastable structure, and the support structure includes a plurality of locking structures; the locking structures and a main structure for molding in the ceramic core are integrally formed, and the main structure is composed of a plurality of molding units, and each molding unit is integrally connected to at least one locking structure; at least one end of the locking structure extends to the opening of the cavity.

[0006] A further improvement of the present invention is: Preferably, the locking structure is any one of columnar, annular or block-shaped structures or a combination of two or more structures.

[0007] Preferably, the locking structure is provided with a force-bearing end at the end of the cavity opening, and the cross-sectional area of ​​the force-bearing end is larger than the cross-sectional area of ​​the locking structure.

[0008] Preferably, the number and positions of the locking structures are determined by numerical simulation.

[0009] Preferably, the locking structure is arranged at the main load-bearing axis of the entire cavity filling structure.

[0010] Preferably, the cross-sectional area of ​​the connection position between the locking structure and the molding unit is larger than the cross-sectional area of ​​other positions.

[0011] Preferably, the locking structure can collapse when subjected to external force or when external conditions change.

[0012] Preferably, the external force is a mechanical force applied to the end of the locking structure; and the external condition is a chemical reaction or a temperature change.

[0013] A method for preparing a 3D printed ceramic core of the self-collapsing structure according to any one of the above items, comprising the following steps: Step 1, weighing and preparing raw materials; Step 2, mixing the raw materials according to a set ratio to form a ceramic slurry; Step 3, 3D printing the ceramic slurry according to the set shape through 3D printing to obtain a molded part; Step 4: Dewaxing and sintering the molded part to obtain a ceramic core.

[0014] Preferably, in step 2, the ceramic slurry composition ratios of the support structure and the main structure are different.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a 3D printed ceramic core with a self-collapsing structure, wherein the 3D printed ceramic core is provided with an internal locking structure in the overall structure of the ceramic core, and the internal locking structure and the main structure of the ceramic core are integrally formed and are a part of the ceramic core. The main structure of the ceramic core is composed of a plurality of molding units, and the molding units serve as molding molds, and each molding unit is connected to at least one locking structure. The internal locking can effectively maintain the structural stability of the ceramic core under high temperature and high pressure conditions, and at the same time, can enhance the overall strength of the core, and better withstand the impact force and static pressure of the metal liquid during the pouring process; while improving the overall stability of the ceramic core, the internal locking structure is connected to the main structure of the core, so that one end thereof can be automatically destroyed and collapsed after being triggered by a predetermined external force or a specific condition, and further drives the molding units in the main structure of the ceramic core to collapse, and then the entire ceramic core can collapse in the cavity.

[0016] The self-collapsing structure can improve the core removal performance, significantly reduce the scrap rate of castings, and improve production efficiency. It reduces the extra operation steps and time consumption caused by the difficulty of core removal, thereby reducing production costs. The above two self-collapsing structures of 3D printed ceramic cores are not only suitable for traditional investment casting processes, but can also be extended to other manufacturing fields that require complex internal structures.

[0017] Furthermore, through numerical simulation optimization, the shape and size of the ceramic core can be precisely controlled to improve material utilization. More precise design and production processes reduce material waste and further improve economic benefits.

[0018] The self-collapsing 3D printed ceramic core and the preparation method thereof of the present invention have significant technical advantages in terms of structural stability, core removal performance, production efficiency, cost-effectiveness, material utilization rate and application scope, and can promote the rapid development of ceramic core manufacturing technology; BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Schematic diagram of a 3D printed ceramic core with a self-collapsing structure in Example 2. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings: Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0020] Example 1 This embodiment provides a 3D printed ceramic core with a self-collapsing structure. The main structure of the ceramic core structure usually changes with the different structures of the molded parts. The main structure is usually composed of multiple molding units, and these molding units are usually separated by gaps. The gaps not only provide channels for the immersion molding of the casting liquid, but also enable the connection relationship and position relationship between the molding units to be flexibly adjusted according to the final molded part structure. The connection relationship and position relationship between the molding units are also determined by the final molded part structure. The ceramic core structure is arranged in the mold cavity.

[0021] Based on the above-mentioned main structure, the present invention is provided with an internal support structure, which is a metastable structure, and the support structure includes a plurality of locking structures; the internal locking structure is used to support the entire main structure, and is connected to all molding units inside the main structure at the same time, so that it can provide support force for the molding units, and at least one end of the internal locking structure is outside the entire cavity, so that the internal locking structure can apply pressure to it from the outside. This structure enables the internal locking structure to improve the overall stability of the ceramic core, while one end of the internal locking structure can automatically destroy and collapse after being triggered by a predetermined external force or specific conditions, and further can drive the balance force of the molding unit that can be connected to it to be destroyed. If both ends of a locking structure are at the opening of the cavity, it is more conducive to the destruction of the entire locking structure.

[0022] In some specific embodiments of the present invention, the locking structure can be a columnar, annular or other simple and regular structure, and the cross-sectional size is determined according to the actual needs of the core structure. The structure can be connected to multiple molding units, and the outer end is easy to apply external force. At the same time, the locking structure with a regular structure rather than a special-shaped structure is selected to ensure that the locking structure can first self-collapse under the action of external force, to prevent the self-collapse of other supporting structures from being difficult to achieve due to the complex structure when the external force is applied. For example, a columnar linear locking structure is prone to self-collapse when an external force is applied at one end, but if the locking structure is a bent or other complex structure, even if one end is subjected to external force, the interior cannot be guaranteed to be completely destroyed.

[0023] It should be understood that the basic principle of setting the locking structure needs to ensure that each internal main structure is stable during the metal casting process, but the direction of the force applied by the locking structure is unstable.

[0024] In some specific embodiments of the present invention, the locking structure is provided with a force-bearing end at the end of the cavity opening, and the cross-section of the force-bearing end is larger than the cross-section supporting the locking structure, so as to facilitate the application of external force. The setting of the force-bearing end makes it easy to apply external force to the locking structure.

[0025] In some specific embodiments of the present invention, the number and position of the locking structure are obtained through numerical simulation. The principle of the numerical simulation process is that the locking structure can stabilize the molding unit so that the molding unit is evenly stressed and does not affect the metal casting process. The other end of the molding unit can be at the opening of the cavity. Figure 1 The opening is set at the lower end of the entire cavity structure. If the pouring port of the cavity structure is at the side end or the upper end, the setting direction of the locking structure can be changed according to the actual situation, and one end of the locking structure can be set at the side end or the upper end. Therefore, based on the above principle, it can be known that one end of the locking structure in the present invention is adjusted with the opening position of the cavity, or the opening position of the cavity is adjusted with the end of the locking structure.

[0026] As a preferred solution, the opening position of the end of the locking structure is as far away from the pouring port of the cavity as possible to prevent the pouring process from affecting the stability of the locking structure.

[0027] In some specific embodiments of the present invention, the locking structures are distributed in an array with equal spacing within the main structure, so as to provide uniform support force for the molding unit.

[0028] In some specific embodiments, the location and number of the locking structures arranged in an equidistant array are determined by numerical simulation.

[0029] In some specific embodiments of the present invention, the cross-sectional area of ​​the connection position between the locking structure and the molding unit is larger than the cross-sectional area of ​​other positions, see Figure 1 In the figure, the connection position between the columnar locking structure and the molding unit is umbrella-shaped. The locking structure is thickened at this position, which can strengthen the connection force with the molding unit and provide a more stable supporting force for the molding unit. At the same time, when collapse occurs, due to the strong connection force, once the locking unit collapses, it is easy to drive the molding unit to collapse.

[0030] When casting is completed and core removal is required, the destruction condition of the internal locking structure is triggered to achieve self-collapse of the component. The locking structure collapses when subjected to external force or changes in external conditions. The predetermined external force includes mechanical force or thermal energy, and the specific condition is a chemical reaction or temperature change. Specifically, the external force is an external force applied to the end of the locking structure. For example, in an umbrella-shaped self-collapsing structure, a torque or pressure is applied to the umbrella-shaped handle structure, so that the ceramic truss pressure-bearing structure becomes tensile, breaks, and then collapses. For example, changing the temperature environment of the entire cavity, or applying a certain external force to the entire cavity. Once the locking structure receives the external force, it will help the entire molding unit to self-collapse. In a specific embodiment, a plurality of locking structures are provided, and an external force needs to be applied to each locking structure so that the internal molding unit can collapse.

[0031] To sum up, the internal locking structure in this embodiment is used to maintain the structural stability of the ceramic core; the internal locking structure can be destroyed after being triggered by a predetermined external force or specific conditions; the component can self-collapse after the internal locking structure is destroyed, so that it can be removed from the inside of the metal part.

[0032] As a preferred solution, in order to ensure that the locking structure itself has a strong connection force while other molding units are easy to collapse, the formula of the locking structure during printing can be adjusted during the 3D printing process to strengthen the connection between its own ceramics, while the main structure of the molding unit itself can be slightly sparse while ensuring that it can withstand the pressure of the pouring process; this solution allows the externally applied force to be stably transmitted to the entire locking structure, and the entire locking structure can drive other molding units, making the molding units more likely to collapse.

[0033] Example 2 This embodiment provides a method for preparing a 3D printed ceramic core with a self-collapsing structure. The main structure of the ceramic core structure usually changes with the different structures of the molded parts. The main structure is usually composed of multiple molding units. There are usually gaps between these molding units for immersion molding of the casting liquid. The connection relationship and position relationship between the molding units are also determined by the final molded part structure. The ceramic core structure is set in the mold cavity. The preparation method of the ceramic core includes the following steps: Step 1: Select raw materials and prepare them according to the target ingredients.

[0034] The raw materials of ceramic cores mainly include refractory matrix materials, mineralizers and additives. Commonly used refractory matrix materials include quartz, corundum, etc., mineralizers include zircon powder, magnesium oxide, yttrium oxide, etc., and additives may include plasticizers, reinforcing agents, pore formers, etc. The ratio of these raw materials needs to be selected according to the specific use and performance requirements of the ceramic core.

[0035] Step 2: Raw material mixing and slurry preparation The selected raw materials are mixed evenly in a certain proportion to form a ceramic slurry with good fluidity. This step usually involves mixing processes such as ball milling to ensure sufficient mixing of the raw materials and uniformity of the slurry.

[0036] Step 3: Forming through three-dimensional (3D) printing technology.

[0037] Step 4: Dewaxing and sintering For ceramic core blanks containing wax, dewaxing treatment is required. After dewaxing, the blank is placed in a sintering furnace for high-temperature sintering to obtain a dense ceramic core.

[0038] Step 5: Shaping and strengthening In the method of the present invention, since a locking structure is provided inside the entire ceramic core, the structure of the ceramic core is more complex than that of a general ceramic core. Therefore, 3D printing helps to form a complex ceramic core.

[0039] Example 3 In a specific embodiment of the present invention, see Figure 1 , Figure 1 The main structure of the ceramic core inside the medium-sized cavity is composed of molding units. The molding units are sheets with a certain thickness. There are gaps between the upper and lower adjacent molding units. The molding units are inclined relative to the locking structure. One end of all the molding units is integrally connected to the middle locking structure. An opening structure is provided on a side wall of the cavity structure, so one end of the locking structure is arranged at the opening. The main body of the locking structure is columnar. The locking structure is arranged on the main load-bearing axis of the entire cavity filling structure. According to the connection position of the molding unit, it is arranged as an umbrella-shaped structure that is integrally connected and stacked in sequence up and down, and the side end of each umbrella-shaped structure is connected to the supporting structure.

[0040] From the above-mentioned Examples 1 to 3, it can be seen that the core of the ceramic core of the present invention is a self-collapsing structure, and the interior of the ceramic core is a semi-stable load-bearing structure optimized by numerical simulation. It is stable in one force direction and unsteady in another force direction. Figure 1 As shown, when the intermediate locking structure is not under pressure, the internal supporting structure is stable, but when it is under pressure, the original structure will be destroyed, causing self-collapse.

[0041] The internal locking structure in this embodiment is not only used to maintain the structural stability of the ceramic core, but also because a locking structure is provided, the 3D printing process is simpler. The structure can also be destroyed when triggered by a predetermined external force or specific conditions, so that the component can self-collapse after the internal locking structure is destroyed, thereby being easily removed from the inside of the metal part.

[0042] The printed ceramic cores can be used in the aerospace, automotive, electronics or medical fields.

[0043] The 3D printed ceramic core with a self-collapsing structure disclosed by the present invention can ensure the high temperature performance of the ceramic core without losing the core removal performance, and has the following characteristics: (1) Structural stability Internal locking structure: The internal locking structure optimized by numerical simulation can effectively maintain the structural stability of the ceramic core under high temperature and high pressure conditions.

[0044] Load-bearing capacity: This structure not only enhances the overall strength of the core, but also better withstands the impact force and static pressure of the molten metal during the pouring process.

[0045] (2) Core stripping performance Self-collapse characteristics: The internal locking structure can automatically destroy and collapse after being triggered by a predetermined external force or specific conditions (such as temperature change, chemical reaction, etc.).

[0046] Easier to remove: The collapsed ceramic core fragments can be more fully mixed and reacted with the core removal solution, resulting in a cleaner and more efficient core removal process.

[0047] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, the first feature "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features not being in direct contact but being in contact through another feature between them.

[0048] In the description of the present invention, “on”, “over” and “above” a first feature from a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0049] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0051] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A 3D printed ceramic core with a self-collapsing structure, characterized in that: The internal support structure in the ceramic core is a metastable structure, and the support structure includes a plurality of locking structures; the locking structure and the main structure used for molding in the ceramic core are integrally formed, and the main structure is composed of a plurality of molding units, and each molding unit is integrally connected to at least one locking structure; at least one end of the locking structure extends to the opening of the cavity.

2. A 3D printed ceramic core with a self-collapsing structure according to claim 1, characterized in that: The locking structure is any one of columnar, annular or block-shaped structures or a combination of two or more structures.

3. A 3D printed ceramic core with a self-collapsing structure according to claim 2, characterized in that: The locking structure is provided with a force-bearing end at the end of the cavity opening, and the cross-sectional area of ​​the force-bearing end is larger than the cross-sectional area of ​​the locking structure.

4. A 3D printed ceramic core with a self-collapsing structure according to claim 1, characterized in that: The number and positions of the locking structures are determined through numerical simulation.

5. The 3D printed ceramic core with a self-collapsing structure according to claim 1, characterized in that: The locking structure is arranged at the main load-bearing axis of the entire cavity filling structure.

6. The 3D printed ceramic core with a self-collapsing structure according to claim 1, characterized in that: The cross-sectional area of ​​the connection position between the locking structure and the molding unit is larger than the cross-sectional area of ​​other positions.

7. The 3D printed ceramic core with a self-collapsing structure according to claim 1, characterized in that: The locking structure can collapse when subjected to external forces or changes in external conditions.

8. The 3D printed ceramic core with a self-collapsing structure according to claim 7, characterized in that: The external force is a mechanical force applied to the end of the locking structure; the external condition is a chemical reaction or a temperature change.

9. A method for preparing the 3D printed ceramic core of the self-collapsing structure according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1, weighing and preparing raw materials; Step 2, mixing the raw materials according to a set ratio to form a ceramic slurry; Step 3, 3D printing the ceramic slurry according to the set shape through 3D printing to obtain a molded part; Step 4: Dewaxing and sintering the molded part to obtain a ceramic core.

10. The method for preparing a 3D printed ceramic core with a self-collapsing structure according to claim 9, characterized in that: In step 2, the ceramic slurry composition ratios of the support structure and the main structure are different.

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