Precision casting process of turbine blade based on local heat dissipation adjustment of ceramic mold shell

Abstract

The application relates to a turbine blade precision casting process based on local heat dissipation adjustment of a ceramic mold shell, and relates to the technical field of turbine blade precision casting.The turbine blade precision casting process comprises the following steps: preparing a tooling, the tooling comprising a base provided with a containing cavity, a recess, and a pouring opening and an exhaust opening communicated to the recess; locking the base with the convex surface adjustment area facing upwards; spraying silicon carbide particles from the pouring opening so that the silicon carbide particles adhere to the convex surface adjustment area; then injecting polyurethane foam; after the polyurethane foam is solidified, polyurethane blocks and polyurethane protrusions filling the pouring opening and the exhaust opening are formed; after the tooling is removed, slurry adhesion and sand spraying are carried out; after baking, the silicon carbide particles form a heat exchange layer, the polyurethane blocks are decomposed to form cavities, and the polyurethane protrusions are decomposed to form two air vents; and during casting, the two air vents are connected to an air cooling system to perform heat exchange. According to the application, the heat exchange layer and the air cooling heat dissipation enable the heat of the convex surface adjustment area to be quickly conducted out, the formation of inclusions and freckle defects is effectively inhibited, and the yield of turbine blades is improved.

Description

Technical Field

[0001] This application relates to the technical field of precision casting of turbine blades, and in particular to the local performance adjustment of precision casting of turbine blades. Background Technology

[0002] The turbine blades of aero-engines and ground-based gas turbines have twisted profiles and complex structures, making them impossible to form through conventional machining. Therefore, they must be manufactured using precision casting. A ceramic mold shell serves as the carrier for the precision forming of turbine blades. Its preparation process involves: first, preparing a wax model of the turbine blade; then, subjecting the wax model to a cyclical process of applying slurry and sand, increasing the mold shell thickness by one layer with each cycle. After multiple cycles, the desired forming thickness is achieved. Finally, the ceramic mold shell is obtained through dewaxing and firing. This ceramic mold shell is then used for casting the turbine blades.

[0003] However, ceramic mold shells are typically designed and manufactured as a single, uniform structure, with roughly the same wall thickness across all parts. This makes it difficult to tailor localized adjustments to the varying heat dissipation requirements of different sections of the turbine blade. Particularly at the junction of the blade and the blade body, the complex geometry leads to heat accumulation and a significant temperature gradient between this area and other parts. This results in uneven solidification of the casting, increasing the risk of solidification defects such as impurities and freckles. Therefore, a process is urgently needed to precisely adjust the localized heat dissipation performance of the ceramic mold shell. Summary of the Invention

[0004] The purpose of this invention is to provide a precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell, so as to solve at least one of the above-mentioned technical problems.

[0005] The technical problem solved by this invention can be achieved by the following technical solutions:

[0006] The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shells includes applying slurry and sand to turbine blade wax molds to form an inner mold shell blank layer.

[0007] The inner mold shell blank layer has an inner mold shell blank transition section at the connection between the flange forming position and the blade forming position. The inner mold shell blank transition section has a convex adjustment area corresponding to the root of the convex side of the blade and the root of the flange.

[0008] Prepare work clothes:

[0009] The tooling includes a base with a downward-opening receiving cavity that accommodates the inner mold shell blank transition section;

[0010] The base is equipped with a locking mechanism to lock the inner mold shell blank layer;

[0011] The base has a recess above the receiving cavity, and the opening edge of the recess covers the convex adjustment area;

[0012] The base is fitted with a sealing ring surrounding the recessed opening;

[0013] The base is provided with an injection port and an exhaust port, which are connected to the recessed area through the recessed upper bottom;

[0014] S1: The convex adjustment area faces upward, and the base is set above the inner mold shell blank layer;

[0015] A layer of paraffin is sprayed onto the inner wall of the recess, the base is locked to the transition section of the inner mold blank, and the sealing ring seals the recess above the convex adjustment area.

[0016] A nozzle extends into the recess from the injection port, spraying silicon carbide particles mixed with an inorganic binder. The silicon carbide particles adhere to the convex adjustment area through the inorganic binder.

[0017] Remove the nozzle and inject polyurethane foam into the depression through the injection port to form a polyurethane block covered with silicon carbide particles. The air in the depression is discharged from the exhaust port.

[0018] At least a section of the polyurethane foam filling inlet and outlet forms a polyurethane protrusion connected to the polyurethane block;

[0019] After removing the tooling, the inner wall of the recess was separated from the polyurethane block through the paraffin layer.

[0020] S2: The inner mold shell blank layer and polyurethane block are subjected to slurry and sand-spraying cycles, avoiding the top of the polyurethane protrusions, until the firing thickness is reached. During firing, the polyurethane block and polyurethane protrusions decompose, and a ceramic mold shell is obtained after firing.

[0021] Silicon carbide particles mixed with inorganic binder form a porous heat exchange layer. The ceramic mold shell forms a cavity that contacts the heat exchange layer at the decomposition point of the polyurethane block. At the two polyurethane protrusions, it decomposes into vents that connect to the cavity.

[0022] S3: The ceramic mold shell is used for casting process. The two vents are connected to the air inlet and air outlet of an air-cooling system, respectively. The cooling gas enters the cavity from one of the vents, exchanges heat with the heat exchange layer, and then exits from the other vent.

[0023] This application selects the convex surface adjustment area at the junction of the blade's convex side root and the cusp root, primarily based on considerations of heat dissipation geometry. The convex shape of the surface determines that the path of heat dissipation along the surface is shorter and more dispersed than that of a concave surface. In other words, under the same cooling conditions, the heat dissipation efficiency of the convex surface is inherently higher than that of the concave surface. Therefore, applying cooling to the convex surface further amplifies the cooling efficiency, resulting in a higher return on investment in cooling resources. Thus, this application focuses on the convex surface area for heat dissipation adjustment, fully utilizing its inherent heat dissipation geometry and coordinating it with the silicon carbide heat exchange layer and air-cooled cavity to enhance the heat dissipation performance of this area.

[0024] This application creates a wall thickness reduction zone in the convex adjustment area of ​​the inner mold shell blank layer to shorten the heat conduction path from the casting surface to the outer wall of the ceramic mold shell, reducing the thermal resistance in this area. Subsequently, silicon carbide particles are introduced at specific points on the thinned area to construct a porous heat exchange layer. The filling of polyurethane foam and the exhaust port on the base are achieved through coordinated operation, thus preventing the pressure inside the storage cavity from increasing during polyurethane foam injection, which could lead to separation between the base and the inner mold shell blank layer. Furthermore, after the polyurethane foam cures, the polyurethane protrusions in the filling port and exhaust port are completely preserved and remain exposed during subsequent shell-making processes. Finally, after calcination and decomposition, two vents are simultaneously formed, laying the foundation for the subsequent integration of an air-cooling system and heat dissipation through this system.

[0025] When the air-cooling system introduces cooling gas into the cavity through these two vents, the cooling gas can fully contact the surface of the heat exchange layer, achieving heat exchange between the cooling gas and the heat exchange layer. Since the heat exchange layer is composed of silicon carbide particles with high thermal conductivity, the heat accumulated at the root of the convex side of the blade and the root of the blade edge is quickly dissipated, significantly reducing the accumulation of heat in this area. This effectively suppresses solidification defects in this area and significantly improves the yield of turbine blades.

[0026] Preferably, the injection port is conical, and the inner diameter of the end of the injection port facing the recess is larger than the inner diameter of the end of the injection port away from the recess.

[0027] The exhaust port is conical, and the inner diameter of the end of the exhaust port facing the recess is larger than the inner diameter of the end of the exhaust port away from the recess.

[0028] By setting the inlet and outlet to be conical with a larger inner diameter towards the concave end than towards the convex end, the flow velocity of the cooling gas decreases as it enters the cavity from the outside through the expansion section. This facilitates uniform diffusion of the cooling gas within the cavity, preventing the formation of concentrated jets and ensuring effective heat exchange across the entire heat exchange layer surface. As the gas, carrying heat, exits the cavity after heat exchange, its flow velocity gradually increases through the contraction section, rapidly dissipating the high temperature and thus enhancing the heat exchange efficiency within the cavity.

[0029] Meanwhile, the injection port and vent are designed to be tapered, with the inner diameter of the concave end being larger than that of the venting end. This allows the tapered wall to separate smoothly from the polyurethane protrusions when the tooling is removed, preventing damage to the two polyurethane protrusions during tooling removal. This improves heat exchange efficiency while ensuring the practicality of the heat dissipation solution.

[0030] Preferably, the recessed upper bottom of the base is provided with a downwardly protruding stop;

[0031] The stop block is located between the line connecting the injection port and the vent port;

[0032] The S1 further includes: injecting polyurethane foam into the recess from the injection port to form a polyurethane block covering silicon carbide particles, and forming a recess at the top of the polyurethane block at the stop.

[0033] The S2 further includes: performing a cyclic operation of applying slurry and applying sand to the pit until the firing thickness is reached, and forming a ceramic protrusion protruding into the cavity at the pit after firing. The ceramic protrusion is used to block the cooling gas from flowing directly from one vent to another.

[0034] The baffle on the base is positioned between the inlet and outlet. After the polyurethane foam cures, a pit forms on the top of the polyurethane block. After slurry application, sanding, and firing, it transforms into a ceramic protrusion located between the two outlets. When cooling gas is introduced into the cavity, the ceramic protrusion blocks the straight path between the two outlets, forcing the cooling gas to bypass the side of the ceramic protrusion after entering through the inlet to reach the outlet. This makes the entire cavity an effective airflow area, allowing the heat exchange layer surface to fully contact the cooling gas. Consequently, under the same airflow, the amount of heat carried away by the cooling gas increases significantly, greatly enhancing the actual heat dissipation efficiency of the air-cooled system.

[0035] Preferably, the inner mold shell blank transition section has a concave surface area corresponding to the root of the concave side of the blade and the root of the fin plate;

[0036] The locking mechanism includes a clamping block;

[0037] The clamping block has a clamping surface covering the concave area, and an elastic rubber layer is provided on the clamping surface of the clamping block;

[0038] The clamping block is provided with at least two bolts, and the receiving cavity of the base is provided with at least two screw holes at intervals along its edge;

[0039] At least two screw holes and at least two bolts, with their positions corresponding one-to-one;

[0040] The bolts on the clamping block are threaded into the screw holes of the base;

[0041] This results in a locking mechanism in which the clamping block locks the inner mold shell blank layer to the base.

[0042] In this application, the locking mechanism uses a combination of clamping blocks and bolts to lock the inner mold shell blank layer to the base. The clamping surface of the clamping block covers the concave root area of ​​the blade side and the concave area of ​​the flange root. The elastic rubber layer on the clamping surface undergoes elastic deformation when the bolt is tightened, which can distribute the bolt tightening force into a uniform surface pressure, avoiding excessive local stress that could cause cracks in the unbaked inner mold shell blank layer. At the same time, the elastic rubber layer can adaptively fill the microscopic gap between the clamping surface and the concave area, enabling a tight fit between the clamping block and the inner mold shell blank layer, further improving the stability of the tooling locking.

[0043] Preferably, the surface of the receiving cavity of the base is provided with an elastic rubber layer.

[0044] When the base is locked, the elastic rubber layer undergoes elastic deformation to actively fill the uneven areas on the surface of the inner mold shell blank, achieving a large-area tight fit between the base and the inner mold shell blank, effectively eliminating local gaps and significantly improving the stability of the tooling positioning. At the same time, the flexible cushioning of the elastic rubber layer avoids rigid contact between the base and the inner mold shell blank, preventing the risk of cracks in the inner mold shell blank caused by rigid contact.

[0045] Preferably, the receiving cavity has a supporting structure that supports the convex adjustment area;

[0046] The recess is provided on the supporting structure;

[0047] The injection port and vent of the base are both connected to the recess of the supporting structure.

[0048] The surface shape of the supporting structure can be precisely customized according to the actual contour of the convex adjustment area, so that the edge of the recessed opening precisely matches the boundary of the convex adjustment area, ensuring that the silicon carbide particles are precisely confined to the area where heat dissipation needs to be enhanced during spraying.

[0049] Preferably, the supporting structure and the base are separate structures;

[0050] The supporting structure is detachably installed within the receiving cavity of the base;

[0051] An O-ring is provided at the joint surface between the base and the supporting structure, and the O-ring surrounds the injection port and the vent port.

[0052] When the base and the supporting structure are assembled, the O-ring seals the gap between the base and the supporting structure.

[0053] The support structure can be independently designed and manufactured according to the convex adjustment area of ​​different turbine blade models or the contour of different special parts, while the base remains unchanged as a universal component. When different products need to be processed, only the support structure matching the target area needs to be replaced to quickly complete the tooling conversion. There is no need to remanufacture the entire set of tooling, which greatly reduces production costs.

[0054] Meanwhile, the O-rings surrounding the injection port and vent at the interface between the base and the supporting structure are compressed and fill the microscopic gaps in the interface after assembly and locking, effectively preventing silicon carbide particles and polyurethane foam from leaking along the interface during injection and ensuring the shape accuracy of the heat exchange layer.

[0055] Preferably, the base has a groove in its receiving cavity, and the supporting structure has a slider that slides in cooperation with the groove.

[0056] The base has a pin hole that runs horizontally through the sliding groove; this pin hole is called the base pin hole.

[0057] The slider has a pin hole that extends laterally through it; this pin hole is called the slider pin hole.

[0058] It also includes a positioning pin;

[0059] The positioning pin passes through the base pin hole and the slider pin hole, and fixes the support structure to the base.

[0060] When the support structure slides along the slide to the predetermined position, the base pin hole and the slider pin hole are automatically aligned coaxially. Inserting the positioning pin will complete the precise locking and fixing. The entire installation process does not require measuring and adjustment tools, and the operation is extremely simple. Pulling out the positioning pin will allow the support structure to slide out along the slide for quick disassembly, which greatly improves the efficiency of replacing the support structure.

[0061] In summary, this application includes at least one of the following beneficial technical effects:

[0062] 1. This application selects the convex surface adjustment area at the junction of the blade's convex side root and the edge plate root, primarily based on considerations of heat dissipation geometry. The convex shape of the surface determines that the path of heat dissipation along the surface is shorter and more dispersed than that of a concave surface. In other words, under the same cooling conditions, the heat dissipation efficiency of the convex surface is higher than that of the concave surface. Therefore, applying cooling to the convex surface further amplifies the cooling efficiency, resulting in a higher return on investment in cooling resources. Thus, this application uses the convex surface area as the target for heat dissipation adjustment, fully utilizing the inherent heat dissipation geometry of the convex surface, and coordinating it with the silicon carbide heat exchange layer and air-cooled cavity of this solution to enhance the heat dissipation performance of this area.

[0063] 2. This application forms a wall thickness reduction zone in the convex adjustment area of ​​the inner mold shell blank layer to shorten the heat conduction path from the casting surface to the outer wall of the ceramic mold shell, reducing the thermal resistance in this area. Subsequently, silicon carbide particles are introduced at specific points on the thinned area to construct a porous heat exchange layer. The filling of polyurethane foam and the exhaust port on the base are achieved through the coordinated operation of the filling port and the exhaust port, thereby avoiding the pressure increase in the storage cavity during the polyurethane foam injection process, which would lead to the separation of the base and the inner mold shell blank layer. After the polyurethane foam cures, the polyurethane protrusions in the filling port and the exhaust port are completely preserved and remain exposed during the subsequent shell making process. Finally, after calcination and decomposition, two vents are formed simultaneously, which lays the foundation for the subsequent connection of the air cooling system and the heat dissipation through the air cooling system.

[0064] 3. When the air-cooling system introduces cooling gas into the cavity through these two vents, the cooling gas can fully contact the surface of the heat exchange layer, realizing heat exchange between the cooling gas and the heat exchange layer. Since the heat exchange layer is composed of silicon carbide particles with high thermal conductivity, the heat accumulated at the root of the convex side of the blade and the root of the blade edge is quickly dissipated, significantly reducing the accumulation of heat in this area. This effectively suppresses solidification defects in this area and significantly improves the yield of turbine blades. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the tooling and inner mold shell blank layer in Embodiment 1 of this application;

[0066] Figure 2 This first embodiment of the application is a schematic diagram showing the positional relationship between the base, the supporting structure, and the sealing ring;

[0067] Figure 3 for Figure 1 The cross-sectional view along AA shows the positional relationship of the recess, injection port, vent, and stop block;

[0068] Figure 4This is a schematic diagram of the tooling structure in Embodiment 2 of this application, showing the separate structure of the base and the supporting structure.

[0069] Reference numerals in the attached drawings: 1. Inner mold shell blank layer; 2. Base; 3. Recess; 4. Sealing ring; 5. Injection port; 6. Vent; 7. Stop block; 8. Clamping block; 9. Bolt; 10. Supporting structure; 11. O-ring; 12. Slider; 13. Locating pin. Detailed Implementation

[0070] The following is in conjunction with the appendix Figure 1 -Appendix Figure 4 This application will be described in further detail.

[0071] Reference Figure 1 , Figure 2 and Figure 3 The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell includes applying slurry and sand to the turbine blade wax mold to form an inner mold shell blank layer 1. The inner mold shell blank layer 1 has an inner mold shell blank transition section at the connection between the flange forming position and the blade forming position. The inner mold shell blank transition section has a convex adjustment area corresponding to the root of the convex side of the blade and the root of the flange.

[0072] Prepare work clothes:

[0073] The fixture includes a base 2 with a downward-facing receiving cavity that accommodates the inner mold shell blank transition section. The base 2 is equipped with a locking mechanism for locking the inner mold shell blank layer 1. A recess 3 is provided above the receiving cavity on the base 2, and the opening edge of the recess 3 covers the convex adjustment area. A sealing ring 4 is fitted around the opening of the recess 3 on the base 2. The base 2 has a filling port 5 and a venting port 6, which are connected to the recess 3 via the upper bottom of the recess 3.

[0074] S1: The convex adjustment area faces upwards, and the base 2 is positioned above the inner mold shell blank layer 1. A paraffin wax layer is sprayed onto the inner wall of the recess 3. The base 2 is locked to the transition section of the inner mold shell blank, and the sealing ring 4 seals the recess 3 above the convex adjustment area. A nozzle extends into the recess 3 through the injection port 5, spraying silicon carbide particles mixed with an inorganic binder. The silicon carbide particles adhere to the convex adjustment area through the inorganic binder. The nozzle is removed, and polyurethane foam is injected into the recess 3 through the injection port 5, forming a polyurethane block covering the silicon carbide particles. Air within the recess 3 is discharged through the vent port 6. The polyurethane foam fills at least a section of both the injection port 5 and the vent port 6, forming polyurethane protrusions connected to the polyurethane block. The fixture is removed, and the inner wall of the recess 3 separates from the polyurethane block through the paraffin wax layer.

[0075] S2: The inner mold shell blank layer 1 and polyurethane block are subjected to a cyclic process of slurry application and sand application, avoiding the top of the polyurethane protrusions, until the firing thickness is reached. During firing, the polyurethane block and polyurethane protrusions decompose, resulting in a ceramic mold shell. Silicon carbide particles mixed with inorganic binder form a porous heat exchange layer. The ceramic mold shell forms cavities that contact the heat exchange layer at the decomposition points of the polyurethane block, and vents connecting to the cavities are formed at the two polyurethane protrusions.

[0076] S3: The ceramic mold shell is used for casting process. The two vents are connected to the air inlet and air outlet of an air-cooling system, respectively. The cooling gas enters the cavity from one of the vents, exchanges heat with the heat exchange layer, and then exits from the other vent.

[0077] This application selects the convex surface adjustment area at the junction of the blade's convex side root and the cusp root, primarily based on considerations of heat dissipation geometry. The convex shape of the surface determines that the path of heat dissipation along the surface is shorter and more dispersed than that of a concave surface. In other words, under the same cooling conditions, the heat dissipation efficiency of the convex surface is inherently higher than that of the concave surface. Therefore, applying cooling to the convex surface further amplifies the cooling efficiency, resulting in a higher return on investment in cooling resources. Thus, this application focuses on the convex surface area for heat dissipation adjustment, fully utilizing its inherent heat dissipation geometry and coordinating it with the silicon carbide heat exchange layer and air-cooled cavity to enhance the heat dissipation performance of this area.

[0078] This application creates a wall thickness reduction zone in the convex adjustment area of ​​the inner mold shell blank layer 1 to shorten the heat conduction path from the casting surface to the outer wall of the ceramic mold shell, reducing the thermal resistance in this area. Subsequently, silicon carbide particles are introduced at specific points on the thinned area to construct a porous heat exchange layer. The filling of polyurethane foam and the exhaust port 6 on the base 2 are achieved through coordinated operation, thus preventing the pressure inside the storage cavity from increasing during polyurethane foam injection, which could lead to separation between the base 2 and the inner mold shell blank layer 1. Furthermore, after the polyurethane foam cures, the polyurethane protrusions in the filling port 5 and exhaust port 6 are completely preserved and remain exposed during subsequent shell-making processes. Finally, after calcination and decomposition, two vents are simultaneously formed, laying the foundation for the subsequent integration of an air-cooling system and heat dissipation through this system.

[0079] When the air-cooling system introduces cooling gas into the cavity through these two vents, the cooling gas can fully contact the surface of the heat exchange layer, achieving heat exchange between the cooling gas and the heat exchange layer. Since the heat exchange layer is composed of silicon carbide particles with high thermal conductivity, the heat accumulated at the root of the convex side of the blade and the root of the blade edge is quickly dissipated, significantly reducing the accumulation of heat in this area. This effectively suppresses solidification defects in this area and significantly improves the yield of turbine blades.

[0080] Example 1

[0081] Reference Figure 1 , Figure 2 and Figure 3 The inner mold shell blank layer 1 is a ceramic mold shell intermediate body that has been coated with slurry and sanded before firing, representing the turbine blade wax model. The thickness of the inner mold shell blank layer 1 is generally 1-5 mm. The edge plate forming position of the inner mold shell blank layer 1 corresponds to the part of the turbine blade edge plate, and the blade body forming position corresponds to the part of the inner mold shell blank layer 1 corresponding to the turbine blade body. The transition section of the inner mold shell blank at the junction of the two corresponds to the abrupt change in cross-section between the turbine blade edge plate and the blade body. The area in the transition section of the inner mold shell blank corresponding to the root of the convex side of the turbine blade body and the root of the edge plate is the convex adjustment area.

[0082] The contour shape of the receiving cavity of the base 2 is adapted to the outer contour of the inner mold shell blank transition section, allowing the base 2 to cover the outside of the inner mold shell blank transition section from above. The base 2 is recessed inward at the receiving cavity, forming a recess 3. The opening edge of the recess 3 covers the boundary of the convex adjustment area when the base 2 covers the inner mold shell blank transition section. At the same time, the base 2 is provided with an annular groove around the opening of the recess 3, and a sealing ring 4 is embedded in the annular groove. Part of the sealing ring 4 protrudes from the surface of the base 2. When the base 2 is locked to the inner mold shell blank transition section, the sealing ring 4 is compressed and tightly adheres to the surface of the inner mold shell blank layer 1, thereby sealing the gap between the opening edge of the recess 3 and the convex adjustment area. In this embodiment, to improve the reliability of the seal, two annular grooves are provided around the opening of the recess 3, and a sealing ring 4 is provided in both annular grooves.

[0083] The base 2 is provided with an injection port 5 and an exhaust port 6. Both the injection port 5 and the exhaust port 6 are tubular channels that penetrate the interior of the base 2. The injection port 5 and the exhaust port 6 are connected to the interior space of the recess 3 through the upper bottom of the recess 3. The injection port 5 is used to inject material into the recess 3, and the exhaust port 6 is used to expel the gas in the recess 3 when the material is injected, so as to prevent the pressure in the recess 3 from increasing and causing the base 2 to separate from the inner mold shell blank layer 1.

[0084] The convex adjustment area faces upward, meaning the inner mold shell blank layer 1 is set with the convex adjustment area facing upward. The base 2 is set above the inner mold shell blank layer 1, aligning the receiving cavity with the transition section of the inner mold shell blank and covering the outside of the transition section of the inner mold shell blank with the base 2.

[0085] Before the base 2 is assembled to the inner mold shell blank layer 1, a paraffin layer is sprayed onto the inner wall of the recess 3. The paraffin layer serves as a demolding isolation layer during subsequent tooling removal, allowing the cured polyurethane block to be easily separated from the inner wall of the recess 3. After the paraffin layer is sprayed onto the inner wall of the recess 3, the base 2 is locked to the transition section of the inner mold shell blank. The sealing ring 4 is compressed and seals the recess 3 above the convex adjustment area. The recess 3 and the outer surface of the convex adjustment area together form a sealed chamber.

[0086] Subsequently, a nozzle is inserted into the recess 3 through the injection port 5. The nozzle's spray nozzle extends into the internal space of the recess 3 and sprays silicon carbide particles mixed with an inorganic binder toward the convex adjustment area. The inorganic binder can be silica sol or water glass. The silicon carbide particles adhere to the outer surface of the convex adjustment area through the inorganic binder, forming a silicon carbide particle layer covering the convex adjustment area.

[0087] After spraying, remove the nozzle and inject polyurethane foam into the depression 3 through the injection port 5. During injection, the polyurethane foam gradually expands and fills the internal space of the depression 3, covering the silicon carbide particles. During the polyurethane foam injection process, air inside the depression 3 is expelled through the vent port 6. Simultaneously, at least a section of both the injection port 5 and the vent port 6 is filled during the injection process. The operator can determine whether the polyurethane foam has been completely filled through the vent port 6. After the polyurethane foam is fully injected and has cured, the polyurethane foam covering the silicon carbide particles solidifies to form a polyurethane block, while the polyurethane foam in the injection port 5 and the vent port 6 forms polyurethane protrusions connected to the polyurethane block.

[0088] After the polyurethane foam has fully cured, the fixture is removed. Because the inner wall of the recess 3 is coated with a paraffin layer, the adhesion between the polyurethane block and the inner wall of the recess 3 is extremely low, and the base 2 can be easily lifted upwards and separated from the polyurethane block. Furthermore, during the upward demolding process of the base 2, the polyurethane protrusions are released from the injection port 5 and the vent port 6.

[0089] The inner mold shell blank layer 1 and the polyurethane blocks attached to it undergo a cyclical process of applying slurry and applying slurry. Each time the slurry and slurry application is completed, the mold shell thickens by one layer. During the slurry and slurry application process, the tops of the polyurethane protrusions are avoided; that is, the tops of the polyurethane protrusions are not subjected to slurry and slurry application, keeping them exposed and not covered by ceramic slurry. This cyclical process continues until the mold shell reaches the predetermined firing thickness.

[0090] After reaching the required thickness, a firing process is performed. During firing, the polyurethane block and polyurethane protrusions undergo thermal decomposition at high temperatures. After firing, a ceramic mold shell is obtained. During firing, the silicon carbide particles mixed with an inorganic binder undergo sintering, connecting the silicon carbide particles to form a porous heat exchange layer. A cavity is formed at the decomposition point of the polyurethane block in the ceramic mold shell, located above the heat exchange layer; the bottom wall of the cavity forms the heat exchange layer. Two vents are formed at the decomposition points of the two polyurethane protrusions in the ceramic mold shell, both of which connect to the cavity.

[0091] The turbine blades are cast using a pre-fired ceramic mold shell, into which molten high-temperature alloy is poured. Two vents are connected to the inlet and outlet pipes of an air-cooling system, which includes a fan, piping, and control valves. Cooling gas enters the cavity through one vent, flows through the heat exchange layer, exchanges heat with it, and then exits through the other vent, thus completing the heat dissipation of the convex area of ​​the inner mold shell blank layer 1.

[0092] Furthermore, the injection port 5 is conical, and the inner diameter of the end of the injection port 5 facing the recess 3 is larger than the inner diameter of the end of the injection port 5 away from the recess 3. The vent port 6 is conical, and the inner diameter of the end of the vent port 6 facing the recess 3 is larger than the inner diameter of the end of the vent port 6 away from the recess 3.

[0093] By setting the inlet 5 and outlet 6 as cones with an inner diameter greater than that of the end facing the recess 3, the flow velocity of the cooling gas decreases as it enters the cavity from the outside through the expansion section. This facilitates uniform diffusion of the cooling gas within the cavity without forming a concentrated jet, allowing the entire surface of the heat exchange layer to effectively participate in heat exchange. As the gas, carrying heat, exits the cavity after heat exchange, its flow velocity gradually increases through the contraction section, enabling rapid removal of high-temperature gases and thus enhancing the heat exchange efficiency within the cavity.

[0094] Meanwhile, the injection port 5 and the exhaust port 6 are set as cones with an inner diameter facing the recess 3 that is larger than the inner diameter away from the recess 3. This allows the cone wall to be easily separated from the polyurethane protrusion when the tooling is removed, avoiding damage to the two polyurethane protrusions during tooling removal. This improves heat exchange efficiency while ensuring the practicality of the heat dissipation solution.

[0095] A downward protruding stop 7 is provided on the upper bottom of the recess 3 of the base 2, and the stop 7 is located between the line connecting the injection port 5 and the vent port 6.

[0096] S1 also includes: injecting polyurethane foam into the recess 3 from the injection port 5 to form a polyurethane block covering silicon carbide particles, with a recess formed on the top of the polyurethane block at the stop 7.

[0097] S2 also includes: performing a cycle of applying slurry and applying sand to the pit until the firing thickness is reached. After firing, the ceramic mold shell forms a ceramic protrusion protruding into the cavity at the pit. The ceramic protrusion is used to block the cooling gas from flowing directly from one vent to another.

[0098] In this embodiment, the stop block 7 and the base 2 are integrally formed. The stop block 7 protrudes downward from the upper bottom surface of the recess 3, and the height of the downward protrusion of the stop block 7 is less than the depth of the recess 3. The shape of the stop block 7 can be cylindrical, inverted frustum, or streamlined. In this embodiment, the stop block 7 is inverted frustum, that is, the diameter of the part where the frustum connects to the lower bottom of the recess 3 is large, and the diameter of the downward protrusion part is small.

[0099] The baffle 7 on the base 2 is positioned between the inlet 5 and the outlet 6. After the polyurethane foam cures, a pit is formed on the top of the polyurethane block. After slurry application, sanding, and firing, it transforms into a ceramic protrusion located between the two outlets. When cooling gas is introduced into the cavity, the ceramic protrusion blocks the straight path between the two outlets, forcing the cooling gas to pass around the side of the ceramic protrusion after entering from the inlet to reach the outlet 6. This makes the entire cavity an effective airflow area, allowing the heat exchange layer surface to fully contact the cooling gas. As a result, under the same airflow, the amount of heat carried away by the cooling gas increases significantly, greatly enhancing the actual heat dissipation efficiency of the air-cooled system.

[0100] Furthermore, the receiving cavity has a supporting structure 10 that supports the convex adjustment area, and a recess 3 is provided on the supporting structure 10. The injection port 5 and the vent port 6 of the base 2 are both connected to the recess 3 of the supporting structure 10.

[0101] In this embodiment, the support structure 10 and the base 2 are integrally molded structures. That is, the support structure 10 is a support structure that partially protrudes from the surface of the receiving cavity. The surface shape of the support structure 10 is adapted to the outer surface contour of the convex adjustment area. The integrally molded support structure 10 and base 2 can be formed by 3D printing. The recess 3 is provided on the support structure 10. That is, the recess 3 is formed by recessing 3 from the surface of the support structure 10 inward. The opening of the recess 3 is located on the surface of the support structure 10.

[0102] The inner mold shell blank transition section also has concave areas corresponding to the root of the concave side of the blade and the root of the flange. The locking mechanism includes a clamping block 8, which has a clamping surface covering the concave area, and an elastic rubber layer is provided on the clamping surface of the clamping block 8. At least two bolts 9 are provided on the clamping block 8, and at least two threaded holes are provided at intervals along the edge of the receiving cavity of the base 2. The at least two threaded holes and at least two bolts 9 are positioned in a one-to-one correspondence. The bolts 9 on the clamping block 8 are threadedly connected to the threaded holes of the base 2, thereby forming a locking mechanism in which the clamping block 8 locks the inner mold shell blank layer 1 to the base 2.

[0103] The locking mechanism uses a clamping block 8 and a bolt 9 to lock the inner mold shell blank layer 1 to the base 2. The clamping surface of the clamping block covers the concave root area of ​​the blade side and the concave area of ​​the flange root. The elastic rubber layer on the clamping surface undergoes elastic deformation when the bolt 9 is tightened, which can distribute the tightening force of the bolt 9 into a uniform surface pressure, avoiding excessive local stress that could cause cracks in the unbaked inner mold shell blank layer 1. At the same time, the elastic rubber layer can adaptively fill the micro gap between the clamping surface and the concave area, so that the clamping block and the inner mold shell blank layer can fit tightly together, further improving the stability of the tooling locking.

[0104] An elastic rubber layer is provided on the surface of the receiving cavity of the base 2. In this embodiment, the material of the elastic rubber layer is EPDM rubber. When the base 2 is locked, the elastic rubber layer undergoes elastic deformation to actively fill the uneven areas on the surface of the inner mold shell blank layer 1, so that the base 2 and the inner mold shell blank layer 1 achieve a large-area tight fit, effectively eliminating local gaps and significantly improving the stability of tooling positioning. At the same time, the flexible cushioning of the elastic rubber layer avoids rigid contact between the base 2 and the inner mold shell blank layer 1, avoiding the risk of cracks in the inner mold shell blank layer 1 caused by rigid contact.

[0105] Example 2

[0106] Reference Figure 4 The difference between this second embodiment and the first embodiment is that the supporting structure 10 and the base 2 are separate structures. The supporting structure 10 is detachably installed in the receiving cavity of the base 2. An O-ring 11 is provided at the mating surface of the base 2 and the supporting structure 10, and the O-ring 11 surrounds the injection port 5 and the vent port 6. When the base 2 and the supporting structure 10 are assembled, the O-ring 11 seals the gap between the base 2 and the supporting structure 10.

[0107] The support structure 10 can be independently designed and manufactured according to the convex adjustment area of ​​different turbine blades or the contour of different special parts, while the base 2 remains unchanged as a general-purpose part. When different products need to be processed, only the support structure 10 that matches the surface of the target area needs to be replaced to quickly complete the tooling conversion. There is no need to remanufacture the entire tooling, which greatly reduces the production cost.

[0108] Meanwhile, the O-ring 11, which surrounds the injection port 5 and the vent port 6 at the joint surface of the base 2 and the supporting structure 10, is compressed and fills the micro gaps of the joint surface after assembly and locking. This effectively prevents silicon carbide particles and polyurethane foam from leaking along the joint surface during the injection process, thus ensuring the shape accuracy of the heat exchange layer.

[0109] Furthermore, a sliding groove is provided within the receiving cavity of the base 2, and a slider 12 that slides in conjunction with the sliding groove is provided on the supporting structure 10. The base 2 has a pin hole that extends laterally through the sliding groove; this pin hole is called the base pin hole. The slider 12 also has a pin hole that extends laterally through the slider 12; this pin hole is called the slider pin hole. A positioning pin 13 is also included, which passes through both the base pin hole and the slider pin hole, fixing the supporting structure 10 and the base 2 together.

[0110] In use, first align the slider 12 of the support structure 10 with the groove in the receiving cavity of the base 2, then push the support structure 10 to slide the slider 12 along the groove to the predetermined installation position. When the support structure 10 slides to the predetermined position, the base pin hole and the slider pin hole automatically align coaxially. At this time, insert the positioning pin 13 through the base pin hole and the slider pin hole to fix the support structure 10 and the base 2. After the base 2 and the support structure 10 are assembled and locked, the O-ring 11 is compressed and fills the micro gaps at the mating surface to achieve a reliable seal. After assembly, follow the steps S1 to S3 in Example 1 to perform silicon carbide particle spraying, polyurethane foam injection, slurry sanding, calcination, and air cooling operations. When it is necessary to replace the support structure 10 to adapt to different models of turbine blades or different special parts, simply pull out the positioning pin 13 to slide the support structure 10 out along the groove, then replace the new support structure 10 and repeat the above installation operation. Throughout the process, the base 2 remains unchanged as a universal component. Installation and disassembly do not require measuring and adjustment tools. The support structure 10 can be quickly replaced simply by using the guide groove and locking with the positioning pin 13.

[0111] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell, comprising applying slurry and sand to a turbine blade wax model to form an inner mold shell blank layer (1), characterized in that, The inner mold shell blank layer (1) has an inner mold shell blank transition section at the connection between the flange forming position and the blade forming position. The inner mold shell blank transition section has a convex adjustment area corresponding to the root of the convex side of the blade and the root of the flange. Prepare work clothes: The tooling includes a base (2), which has a downward-facing receiving cavity that accommodates the inner mold shell blank transition section; The base (2) is provided with a locking mechanism for locking the inner mold shell blank layer (1); The base (2) has a recess (3) above the receiving cavity, and the opening edge of the recess (3) covers the convex adjustment area; The base (2) is fitted with a sealing ring (4) surrounding the opening of the recess (3); The base (2) is provided with a filling port (5) and an exhaust port (6), and the filling port (5) and the exhaust port (6) are connected to the recess (3) through the upper bottom of the recess (3); S1: The convex adjustment area faces upward, and the base (2) is set above the inner mold shell blank layer (1); The inner wall of the recess (3) is sprayed with a layer of paraffin wax, the base (2) is locked to the transition section of the inner mold blank, and the sealing ring (4) seals the recess (3) above the convex adjustment area. A nozzle extends from the injection port (5) into the recess (3) and sprays silicon carbide particles mixed with inorganic binder. The silicon carbide particles adhere to the convex adjustment area through the inorganic binder. Remove the nozzle and inject polyurethane foam into the depression (3) from the injection port (5) to form a polyurethane block covering silicon carbide particles. The air in the depression (3) is discharged from the exhaust port (6). At least one section of the polyurethane foam filling port (5) and the vent (6) is respectively formed as a polyurethane protrusion connected to the polyurethane block; Remove the tooling, and the inner wall of the recess (3) is separated from the polyurethane block through the paraffin layer; S2: Perform cyclic operations of slurry application and sand application on the inner mold shell blank layer (1) and polyurethane block, avoiding the top of the polyurethane protrusion, until the firing thickness is reached. During firing, the polyurethane block and polyurethane protrusion decompose, and a ceramic mold shell is obtained after firing. Silicon carbide particles mixed with inorganic binder form a porous heat exchange layer. The ceramic mold shell forms a cavity that contacts the heat exchange layer at the decomposition point of the polyurethane block. At the two polyurethane protrusions, it decomposes into vents that connect to the cavity. S3: The ceramic mold shell is used for casting process. The two vents are connected to the air inlet and air outlet of an air-cooling system, respectively. The cooling gas enters the cavity from one of the vents, exchanges heat with the heat exchange layer, and then exits from the other vent.

2. The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell according to claim 1, characterized in that, The injection port (5) is conical, and the inner diameter of the end of the injection port (5) facing the recess (3) is greater than the inner diameter of the end of the injection port (5) away from the recess (3). The exhaust port (6) is conical, and the inner diameter of the end of the exhaust port (6) facing the recess (3) is greater than the inner diameter of the end of the exhaust port (6) away from the recess (3).

3. The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell according to claim 1, characterized in that, A downwardly protruding stop (7) is provided on the upper bottom of the recess (3) of the base (2); And the stop block (7) is located between the line connecting the injection port (5) and the exhaust port (6); The S1 further includes: injecting polyurethane foam into the recess (3) from the injection port (5) to form a polyurethane block covering silicon carbide particles, and forming a recess at the top of the polyurethane block at the stop (7). The S2 further includes: performing a cyclic operation of applying slurry and applying sand to the pit until the firing thickness is reached, and forming a ceramic protrusion protruding into the cavity at the pit after firing. The ceramic protrusion is used to block the cooling gas from flowing directly from one vent to another.

4. The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell according to claim 1, characterized in that, The inner mold shell blank transition section has concave areas corresponding to the root of the concave side of the blade and the root of the rim plate; The locking mechanism includes a clamping block (8); The clamping block (8) has a clamping surface covering the concave area, and an elastic rubber layer is provided on the clamping surface of the clamping block (8); The clamping block (8) is provided with at least two bolts (9), and the receiving cavity edge of the base (2) is provided with at least two screw holes at intervals; At least two screw holes and at least two bolts (9) are in one-to-one correspondence; The bolts (9) on the clamping block (8) are threaded into the screw holes of the base (2); This results in a locking mechanism in which the clamping block (8) locks the inner mold shell blank layer (1) to the base (2).

5. The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell according to claim 1, characterized in that, The surface of the receiving cavity of the base (2) is provided with an elastic rubber layer.

6. The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell according to claim 1, characterized in that, The receiving cavity has a supporting structure (10) for supporting the convex adjustment area; The recess (3) is provided on the supporting structure (10); The injection port (5) and vent port (6) of the base (2) are both connected to the recess (3) of the supporting structure (10).

7. The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell according to claim 6, characterized in that, The supporting structure (10) and the base (2) adopt a separate structure; The supporting structure (10) is detachably installed in the receiving cavity of the base (2); An O-ring (11) is provided at the joint surface between the base (2) and the supporting structure (10), and the O-ring (11) surrounds the injection port (5) and the vent (6). When the base (2) and the support structure (10) are assembled, the O-ring (11) seals the gap between the base (2) and the support structure (10).

8. The precision casting process for turbine blades based on local heat dissipation adjustment of ceramic mold shell according to claim 7, characterized in that, The base (2) is provided with a sliding groove in its receiving cavity, and the supporting structure (10) is provided with a slider (12) that slides in cooperation with the sliding groove; The base (2) has a pin hole that runs horizontally through the slide groove. This pin hole is called the base pin hole. The slider (12) has a pin hole that extends horizontally through the slider (12), and this pin hole is called the slider pin hole; It also includes a positioning pin (13); The positioning pin (13) passes through the base pin hole and the slider pin hole, and fixes the support structure (10) and the base (2).

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