A water soluble core forming method for complex internal cavities of a flask wax pattern

Abstract

The present application relates to the field of investment precision casting, and discloses a water-soluble core forming method for complex inner cavity of a machine case wax mold, comprising the following steps: designing a water-soluble core model, and designing a water-soluble core cold core with a split hollow structure according to the water-soluble core model; designing a reinforcing rib at the hollow position of the water-soluble core cold core; combining and bonding the split water-soluble core cold cores to form an integrated water-soluble core cold core; placing the integrated water-soluble core cold core in a water-soluble core mold to press and form a water-soluble core; placing the water-soluble core in a machine case wax mold; pressing the machine case wax mold; and digging a hole or drilling a hole at the position of the water-soluble core head to expose the internal hollow structure; the water-soluble core cold core is designed as a split hollow structure, which greatly reduces the material cost, ensures the size precision of the complex inner cavity of the machine case wax mold, enables the dissolving liquid to enter the water-soluble core to realize the simultaneous dissolution of the inner and outer surfaces, significantly improves the dissolution rate, and shortens the production cycle.

Description

Technical Field

[0001] This invention relates to the field of investment casting, specifically a method for forming water-soluble cores for complex internal cavities in a casing wax model. Background Technology

[0002] The casing is an important component of aero engines and gas turbines. Due to the large internal space of the casing and the small space at the outlet positions on both sides, the wax mold of the casing's internal cavity cannot be directly formed as a whole using movable blocks. The forming of the complex internal cavity of the casing wax mold has always been a difficult problem in investment casting.

[0003] Existing technologies for complex internal cavities in the casing wax model employ either separate wax model processing and assembly, ceramic core molding, or integral water-soluble core molding. The separate wax model processing and assembly method requires not only wax model molds but also assembly fixtures of the same size as the casing, resulting in high manufacturing costs and difficulties in repairing the joints of complex internal cavities. The ceramic core molding method, with its large internal cavity space, necessitates a large ceramic core size. The overall weight of the ceramic core easily deforms the wax model, and its density differs significantly from the shell obtained through normal shell fabrication, potentially leading to metallurgical defects in the internal cavity. Traditional water-soluble core molding first requires pressing the water-soluble core cold core using a pre-formed water-soluble core cold core mold; then placing the water-soluble core cold core in the water-soluble core mold for further pressing; finally, placing the water-soluble core in the wax model mold for pressing the wax model. After pressing, the wax model needs to be dissolved in a weakly acidic aqueous solution to remove the water-soluble core, typically requiring 12-48 hours for the casing water-soluble core to dissolve; ultimately forming the casing wax model. The larger the inner cavity of the casing wax mold, the more water-soluble core is used, the higher the manufacturing cost, and the longer it takes to dissolve in the weak acid aqueous solution. In addition, the water-soluble core is a disposable material and cannot be recycled.

[0004] In view of the technical problems existing in the prior art, such as high manufacturing cost, long dissolution time of water-soluble core, and easy deformation of wax mold, the present invention provides a novel water-soluble core molding method for complex inner cavity of casing wax mold, so as to solve the above problems. Summary of the Invention

[0005] To address the existing problems, this invention provides a water-soluble core molding method for complex internal cavities of casing wax molds, which can effectively solve the problems mentioned in the background art.

[0006] To solve the above problems, the present invention adopts the following technical solution: A method for forming a water-soluble core for a complex inner cavity in a casing wax model, comprising the following steps: S1. Water-soluble core model design: Based on the three-dimensional configuration of the complex internal cavity of the casing, a water-soluble core model is designed; S2. Design a water-soluble core cold core based on the water-soluble core model, configure the water-soluble core cold core as a split hollow structure, wherein the wall thickness of the water-soluble core is 2 to 5 mm, and the wall thickness of the water-soluble core cold core is 3 to 10 mm; S3. Design reinforcing ribs at the hollow position of the water-soluble core cold core; S4. Assemble and bond each separately designed water-soluble core cold core to form an integrated water-soluble core cold core, then place the complete water-soluble core cold core in a water-soluble core mold to press and form the water-soluble core; S5. Place the water-soluble core in a casing wax pattern mold, press the casing wax pattern, and perform hole digging or drilling at the core head position of the water-soluble core to expose the internal hollow structure.

[0007] As a further solution of the present invention: in step S1, a positioning groove is provided on the water-soluble core model.

[0008] As a further solution of the present invention: in step S2, the parting surface of the water-soluble core cold core is designed as a step structure and / or a groove structure, and the separately designed water-soluble core cold cores are connected in a matching manner via the step structure and the groove structure.

[0009] As a further solution of the present invention: in step S2, a wall thickness core support is arranged on the outer side wall of the water-soluble core cold core, and the height of the wall thickness core support is consistent with the wall thickness of the water-soluble core.

[0010] As a further solution of the present invention: in step S3, the thickness of the reinforcing rib is 2 to 5 mm.

[0011] As a further solution of the present invention: the structure of the reinforcing rib is any one of a straight shape, a cross shape or a grid shape.

[0012] As a further solution of the present invention: in step S3, the draft angle is increased according to the depth of the reinforcing rib.

[0013] As a further solution of the present invention: in step S5, the parting surface of the water-soluble core cold core is arranged at the thick and large position in the middle of the water-soluble core cold core.

[0014] Compared with the prior art, the present invention has the following beneficial effects: by designing the water-soluble core cold core as a split hollow structure, the amount of wax material used for the water-soluble core is reduced by about 50% compared with the traditional solid structure, which significantly reduces the material cost; by arranging the reinforcing ribs at the hollow position, the hollow thin-wall structure is ensured to have sufficient strength, deformation during the wax pattern pressing process is avoided, and the dimensional accuracy of the complex inner cavity of the casing wax pattern is guaranteed; by digging or drilling a hole at the core head position of the water-soluble core after the wax pattern is pressed to expose the internal hollow structure, the dissolving liquid can enter the interior of the water-soluble core to realize simultaneous dissolution of the inner and outer surfaces, which significantly improves the dissolution rate, shortens the production cycle, and effectively solves the technical problems of high manufacturing cost, low dissolution efficiency and easy deformation of the wax pattern in the prior art. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the water-soluble core structure in this invention; Figure 2 This is a schematic diagram of the water-soluble core cold core structure in this invention; Figure 3 This is a schematic diagram of the water-soluble core-cold core split structure in this invention; Figure 4 This is a schematic diagram of one of the split structures of the water-soluble core cooling core in this invention; Figure 5 This is a three-dimensional schematic diagram of the casing wax mold structure in this invention; Figure 6 This is a schematic cross-sectional view of the casing wax mold structure in this invention.

[0016] In the diagram: 1. Water-soluble core; 2. Water-soluble core cold core; 3. Stepped structure; 4. Groove structure; 5. Wall thickness core support; 6. Reinforcing rib; 7. Casing wax model; 8. Positioning structure. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Combination Figures 1 to 6 This embodiment describes a method for forming a water-soluble core for complex internal cavities in a casing wax model, specifically including the following steps: S1, Water-soluble Core Model Design like Figure 1 As shown, based on the three-dimensional configuration of the complex inner cavity of the casing, a water-soluble core model 1 is designed. The overall shape of the water-soluble core model 1 matches the shape of the inner cavity of the casing. At the same time, a positioning structure 8 for the water-soluble core model 1 in the wax mold is designed. The positioning structure 8 is a positioning groove, which has two grooves and is located on the top of the water-soluble core model 1 to ensure the precise positioning of the water-soluble core 1 in the wax mold.

[0019] S2, Water-soluble core cooling structure design like Figures 2-4As shown, based on the water-soluble core model 1 designed in step S1, the structure of the water-soluble core cold core 2 is designed. Specifically, the overall wall thickness of the water-soluble core model 1 is set to 2-5mm, and the water-soluble core cold core 2 is designed as a split hollow structure. In this embodiment, the water-soluble core cold core 2 is set as two split structures, and the wall thickness of the water-soluble core cold core 2 is controlled between 3-10mm. The parting surface of the water-soluble core cold core 2 is designed as a stepped structure 3 or a grooved structure 4. Specifically, one split structure water-soluble core cold core 2 is provided with a stepped structure 3, and the other split structure water-soluble core cold core 2 is provided with a grooved structure 4. The split water-soluble core cold cores 2 are connected by a stepped structure 3 and a grooved structure 4 to improve the dimensional accuracy and connection strength of the assembly surface. The outer wall of the water-soluble core cold core 2 is provided with a wall thickness core support 5. The height of the wall thickness core support 5 is the same as the wall thickness of the water-soluble core 1, which is 2-5mm. An assembly gap of 0.1-0.3mm is reserved in the design to ensure the mold closing accuracy.

[0020] The parting surface is generally designed in the thick part of the water-soluble core 1. When the product dimensional accuracy requirements are not high, the water-soluble core 1 can be designed as a split structure and then bonded together. There is no need to design the water-soluble core cold core 2, thereby reducing the number of molds and reducing manufacturing costs.

[0021] S3, Reinforcing Rib Design like Figure 4 As shown, a reinforcing rib 6 is designed in the hollow position of the water-soluble core 2. The thickness of the reinforcing rib 6 is controlled between 2 and 5 mm. Depending on the depth of the reinforcing rib 6, the draft angle can be appropriately increased to improve the strength and dimensional accuracy of the water-soluble core 1 itself. The structural form of the reinforcing rib 6 is "I" shaped. In other embodiments, a "+" shaped or "well" shaped structure can also be adopted. The "+" shaped reinforcing rib 6 provides support in two directions, further improving the overall strength and deformation resistance of the water-soluble core 2. It is suitable for application scenarios where the water-soluble core 1 is large in size and the stress is complex. The "well" shaped reinforcing rib 6 provides uniform support in multiple directions, which can maximize the structural strength of the water-soluble core 2. It is suitable for application scenarios where the water-soluble core 1 is extremely large in size or has a particularly complex structure.

[0022] S4. Water-soluble core cold core mold closing and pressing molding like Figure 3 As shown, the separate water-soluble cores 2 are molded together and glued together at the parting surface to form an integral water-soluble core 2. The complete water-soluble core 2 is placed in the water-soluble core 1 mold and pressed to form the final water-soluble core 1.

[0023] S5. Wax mold pressing and melting hole processing like Figure 5 , Figure 6As shown, the water-soluble core 1 is placed inside the casing wax mold, the casing wax mold 7 is pressed, and a hole is drilled or cut at the core head of the water-soluble core 1 to expose the internal hollow structure of the water-soluble core 1. In this way, in the subsequent weak acid solution dissolution process, the dissolving liquid can quickly enter the internal hollow structure of the water-soluble core 1 and dissolve the water-soluble core 1 from the inside and outside at the same time, which greatly improves the dissolution rate.

[0024] S6, water-soluble core dissolution The casing wax model 7 with the water-soluble core 1 is placed in a weakly acidic aqueous solution for dissolution. Since the water-soluble core 1 has a hollow structure and a through hole at the core head, the dissolving liquid can quickly enter the interior of the water-soluble core 1, and the dissolution time is significantly shortened compared to the 12 to 48 hours of the traditional solid water-soluble core 1.

[0025] The working principle of this invention is: This invention addresses the technical challenges of high material consumption and low dissolution efficiency of the water-soluble core 1 during the molding of the complex inner cavity of the casing wax mold 7. By designing the water-soluble core cold core 2 as a split hollow structure, the filling volume of the water-soluble core 1 wax material is significantly reduced, achieving cost control from the source of material consumption. The realization of this hollow structure relies on the split design, and each split water-soluble core cold core 2 can be demolded independently, thus enabling the complex hollow structure to be successfully prepared by mold forming, solving the process bottleneck of the traditional one-piece structure that cannot be demolded. On this basis, the split water-soluble core cold core 2 are connected by the step structure 3 and the groove structure 4 to achieve mold closing and positioning. This cooperation method not only provides precise assembly positioning, but also enhances the connection strength at the parting surface, preventing cracking or misalignment of the parting surface due to injection pressure during the subsequent wax mold pressing process. The wall thickness core support 5 structure plays a supporting and positioning role during the mold closing process, ensuring that the wall thickness of the hollow structure is uniform and consistent, thereby ensuring the dimensional accuracy of the final inner cavity of the casing wax mold 7. The reinforcing ribs 6 set in the hollow position of the water-soluble core 2 provide the necessary structural rigidity for the water-soluble core 1 under the premise of thinning the wall thickness, avoiding bending or breakage during handling, assembly and wax mold pressing, and ensuring that the hollow thin-walled structure has sufficient strength to resist external pressure. After the casing wax mold 7 is pressed, a hole is drilled or cut at the core head of the water-soluble core 1 to expose the internal hollow structure. When the traditional solid water-soluble core 1 is dissolved in a weak acid solution, the dissolving liquid can only gradually penetrate from the outer surface of the water-soluble core 1 inward. The dissolution rate is limited by the layer-by-layer dissolution process from the outside to the inside, resulting in a small dissolution area and low efficiency. However, this invention allows the dissolving liquid to directly enter the hollow structure inside the water-soluble core 1 through the opening at the core head, realizing the simultaneous dissolution of the inner and outer surfaces of the water-soluble core 1, significantly increasing the dissolution area, and thus greatly shortening the dissolution time. Through the synergistic effect of the three links of "hollow material reduction, reinforcement and strengthening, and opening to increase speed", the dual technical effects of material saving and efficiency improvement are achieved while ensuring the molding quality and dimensional accuracy of the casing wax mold 7.

[0026] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0027] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for forming a water-soluble core for a complex inner cavity in a casing wax model, characterized in that, comprising the following steps: S1. Water-soluble core model design: designing a water-soluble core model according to the three-dimensional configuration of the complex inner cavity of the casing; S2. Designing a water-soluble core cold core according to the water-soluble core model, the water-soluble core cold core is designed as a split hollow structure, the wall thickness of the water-soluble core is 2 to 5 mm, and the wall thickness of the water-soluble core cold core is 3 to 10 mm; S3. Designing reinforcing ribs at the hollow position of the water-soluble core cold core; S4. Closing and bonding the separately designed water-soluble core cold cores to form an integrated water-soluble core cold core, then placing the complete water-soluble core cold core in a water-soluble core mold to press and form the water-soluble core; S5. Placing the water-soluble core in a casing wax pattern mold, pressing a casing wax pattern, and digging or drilling a hole at the core head position of the water-soluble core to expose the internal hollow structure.

2. The method for forming a water-soluble core for a complex inner cavity of a casing wax model according to claim 1, characterized in that, In step S1, a positioning groove is provided on the water-soluble core model.

3. The method for forming a water-soluble core for a complex inner cavity of a casing wax model according to claim 1, characterized in that, In step S2, the parting surface of the water-soluble core cold core is arranged at the thick and large position in the middle of the water-soluble core cold core.

4. The method for forming a water-soluble core for a complex inner cavity of a casing wax model according to claim 1, characterized in that, In step S2, the parting surface of the water-soluble core cold core is designed as a step structure and / or a groove structure, and the separately designed water-soluble core cold cores are connected in a matching manner through the step structure and the groove structure.

5. The method for forming a water-soluble core for a complex inner cavity of a casing wax model according to claim 1, characterized in that, In step S2, a wall thickness core support is provided on the outer side wall of the water-soluble core cold core, and the structure of the core support is consistent with the wall thickness of the water-soluble core.

6. The method for forming a water-soluble core for a complex inner cavity of a casing wax model according to claim 1, characterized in that, In step S3, the thickness of the reinforcing rib is 2 to 5 mm.

7. The method for forming a water-soluble core for a complex inner cavity of a casing wax model according to claim 1, characterized in that, The structure of the reinforcing rib is any one of a straight shape, a cross shape or a grid shape.

8. The method for forming a water-soluble core for a complex inner cavity of a casing wax model according to claim 1, characterized in that, In step S3, the draft angle is increased according to the depth of the reinforcing rib.

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