Preparation method of large single-crystal guide blade

Abstract

The invention discloses a preparation method of a large single crystal guide vane, which comprises the following steps: designing a tool, pre-burying a chassis embedded part of the tool in a chassis wax mold, connecting a pouring cup embedded part with the chassis embedded part by using a connecting rod to support the whole module and ensure the strength of the module, and distributing the connecting rod on the outer side of the chassis to ensure the stability of the module. Therefore, an effective mold assembling area is a whole base plate circular area, a blade wax mold can be drawn close to the middle of the base plate when installed, the outer contour of the blade wax mold cannot exceed the whole base plate range, the whole mold assembly can be smoothly installed in a hearth, and directional pouring of the large-size single crystal blade is achieved. According to the invention, by adding a set of tooling for die assembly, the preparation of the large-size single crystal blade is realized on the premise that the existing directional solidification furnace does not need to be transformed.

Description

Technical Field

[0001] The invention belongs to the technical field of high-temperature alloy single crystal blade preparation, and in particular relates to a method for preparing a large single crystal guide blade. Background Art

[0002] Large-sized single crystal blades can maintain excellent comprehensive mechanical properties, structural stability and anti-oxidation and corrosion properties in high-temperature environments. This makes them key components in high-temperature applications such as aircraft engines and gas turbines, and can withstand higher turbine inlet temperatures and thrust-to-weight ratios, thereby improving the efficiency and performance of the engine. However, due to the size limitations of the company's directional solidification furnace, the existing mold assembly process cannot achieve direct production of large-sized single crystal blades. This is because the existing mold assembly scheme, in order to ensure the strength of the module, will install a central column tube structure in the center of the chassis, resulting in an effective mold assembly area of ​​a circular ring area. The radial size of the module will exceed the effective mold assembly area of ​​the chassis, resulting in the inability to load the furnace. Therefore, it is necessary to transform the existing directional solidification furnace to increase its furnace chamber, but the transformation of the existing equipment will increase the manufacturing cost on the one hand, and on the other hand, due to the increase in the furnace chamber space, the temperature field is more unstable, and large-sized single crystal blades are more likely to produce stray crystal defects during the solidification process, especially in specific areas of the casting, such as sudden sections and corners, where the supercooling phenomenon is more obvious, leading to the formation of stray crystals.

[0003] In summary, how to directly use the existing directional solidification furnace to produce large-sized single crystal blades is a key technical problem that needs to be solved urgently. Summary of the invention

[0004] To this end, the main purpose of the present invention is to provide a method for preparing large single crystal guide vanes, which achieves the preparation of large-sized single crystal blades by increasing the effective mold assembly area of ​​the chassis without the need to modify the existing directional solidification furnace.

[0005] To this end, the present invention provides a method for preparing a large single crystal guide blade, comprising the following steps: Step 1, making a tooling, which includes a chassis embedded part, a connecting rod, a pouring cup embedded part, a pouring cup cover plate and a T-shaped handle; Step 2: Wax pressing Pressing a chassis wax mold, a pouring cup wax mold and a blade wax mold; wherein the chassis embedded parts are embedded in the chassis wax mold, and the pouring cup embedded parts are embedded in the pouring cup wax mold; Step 3: Assemble the model The chassis wax model, the pouring cup wax model and a plurality of blade wax models are combined by using tooling to form a module; wherein a plurality of connecting rods are evenly distributed around the outside of the chassis wax model, and the two ends are detachably fixedly connected to the chassis embedded parts and the pouring cup cover plate respectively, the docking screw of the pouring cup embedded parts matches and passes through the center hole of the pouring cup cover plate and is threadedly connected to the T-handle, the T-handle abuts against the upper end of the pouring cup cover plate, the pouring cup wax model is close to the pouring cup cover plate, the lower end of each blade wax model is connected to the chassis wax model through the crystallization section wax model, and the upper end is connected to the pouring cup wax model through the runner wax model; Step 4: Seal the gap between the pouring cup wax mold and the pouring cup cover with wax liquid, and brush wax on the surfaces of all parts of the tooling except the T-shaped handle; Step 5: The entire module is clamped by a robot or manually held by a T-shaped handle, and the entire module is dipped in slurry, sprinkled with sand, and dried multiple times to form an initial mold shell; Step 6: Remove the T-shaped handle and the pouring cup cover, invert the entire initial mold shell for dewaxing, and after dewaxing is completed, remove the other parts of the tooling to obtain a casting mold shell with a cavity; Step 7: Insert the seed crystal from the bottom of the casting mold into the seed crystal cavity formed after the wax mold of the crystallization section is dewaxed, and then use the casting mold to prepare a single crystal casting.

[0006] Specifically, the blade wax mold is formed on the mold set in an inclined manner, and the crystallization section wax mold is arranged on the chassis at an inclination direction parallel to the blade body axis of the blade wax mold.

[0007] Specifically, a plurality of ceramic support rods for supporting the blade wax model are welded on the wax model chassis.

[0008] Specifically, threaded columns are provided at both ends of the connecting rod, and the diameter of the threaded columns is smaller than the diameter of the connecting rod. When assembling the mold, the chassis gasket is first connected to the corresponding threaded holes on the chassis embedded parts through the connecting screws, and then the threaded columns at the lower end are matched and passed through the connecting holes on the chassis gasket and locked with locking nuts. After that, the docking screws of the pouring cup embedded parts are passed through the pouring cup cover plate, and the T-shaped handles are tightened to make them abut against the pouring cup cover plate, and the pouring cup wax mold is suspended and fixed under the pouring cup cover plate, and then the threaded columns at the upper end are matched and passed through the connecting holes on the pouring cup cover plate and locked with locking nuts to fix the pouring cup cover plate to the upper end of the connecting rod.

[0009] Specifically, a groove is provided on the upper surface of the chassis embedded part.

[0010] Specifically, when the initial mold shell is inverted for dewaxing, the dewaxing pad is covered on the initial mold shell, and the threaded column of the connecting rod is matched and passed through the corresponding connecting hole on the dewaxing pad and then connected to the locking nut. While the dewaxing pad is fixed, its lower surface is pressed against the initial mold shell. A wax drainage hole is provided on the dewaxing pad at the position of the pouring cup wax mold. After loosening and unscrewing the docking screw from the pouring cup embedded part, the entire initial mold shell is inverted, and the dewaxing pad is used to support the initial mold shell for dewaxing.

[0011] Specifically, the following steps are also included: Determine the seed crystal diameter to be used in directional solidification of the casting according to the casting mold assembly plan; Prepare wax molds, each wax mold includes a base plate, a center column tube and a number of wax rods of the same size, the diameter of the wax rods being the same as the diameter of the seed crystal to be used for directional solidification of the casting; Then the wax mold is dipped in slurry and sanded to obtain a preliminary ceramic shell; Afterwards, the preliminary ceramic shell is dewaxed and fired to obtain an experimental shell, and the cavity formed after the wax rod is dewaxed constitutes the seed crystal cavity; An experimental seed crystal is matched and inserted into each seed crystal cavity of the experimental mold shell. The length of the experimental seed crystal inserted into each seed crystal cavity is inconsistent. The lower end of each experimental seed crystal is flush with the bottom plate of the mold shell. The side of each experimental seed crystal is degassed to form a channel for the flow of molten metal between the seed crystal cavities. The material of the experimental seed crystal is the same as the seed crystal material to be used in the directional solidification of the casting. The experimental mold shell is then placed in a solidification furnace to simulate the actual pouring process of the casting; After the experiment, the shell was removed, the experimental seed crystal was cleaned, and the surface state of the experimental seed crystal was observed and recorded. The seed crystal with alloy liquid flowing on the measured surface was axially sectioned, and the section surface was polished and corroded to observe the metallographic structure, and the remelting interface of the experimental seed crystal was determined. Then, the length from the remelting interface to the bottom of the experimental seed crystal was measured, and the original length of the seed crystal was subtracted from this length to obtain the length of the seed crystal remelting section. The experimental seed crystal with a seed crystal remelting section length of 3-4mm was used to prepare the final casting.

[0012] Compared with the prior art, the present invention has the following beneficial effects: by designing tooling, and embedding the chassis embedded parts of the tooling in the chassis wax mold, and then connecting the pouring cup embedded parts with the chassis embedded parts with connecting rods, support is provided for the entire module to ensure the strength of the module, and the connecting rods are distributed on the outside of the chassis and will not occupy the chassis space. Therefore, the effective mold assembly area is the entire circular area of ​​the chassis. When the blade wax mold is installed, it can be close to the middle of the chassis so that its outer contour will not exceed the entire chassis range. The entire module can be smoothly loaded into the furnace to achieve directional casting of large-sized single crystal blades. The present invention achieves the preparation of large-sized single crystal blades by adding a set of mold assembly tooling without modifying the existing directional solidification furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 It is a schematic diagram of the tooling structure provided by an embodiment of the present invention; Figure 2 This is an assembly diagram of a pouring cup cover plate and a tooling provided in an embodiment of the present invention; Figure 3 is a schematic diagram of a module provided by an embodiment of the present invention; Figure 4 It is a schematic diagram of the installation of a dewaxing pad when dewaxing a mold shell according to an embodiment of the present invention; Figure 5 It is the front view of the experimental wax model of the present invention; Figure 6 is a top view of the experimental wax model of the present invention; Figure 7 It is the experimental shell diagram of the present invention; Among them: 1. Chassis embedded parts; 2. Connecting rods; 3. Pouring cup embedded parts; 4. Pouring cup cover plate; 5. Docking screw; 6. T-handle; 7. Chassis wax mold; 8. Pouring cup wax mold; 9. Blade wax mold; 10. Crystallization section wax mold; 11. Runner wax mold; 12. Ceramic support rod; 13. Threaded column; 14. Chassis gasket; 15. Locking nut; 16. Groove; 17. Dewaxing pad; 18. Wax drain hole. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] In the description of the present invention, it is to 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”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0017] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, 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, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0018] A method for preparing a large single crystal guide blade comprises the following steps: Step 1, making a tool, which includes a chassis embedded part 1, a connecting rod 2, a pouring cup embedded part 3, a pouring cup cover plate 4 and a T-shaped handle 6. The chassis embedded part 1 is a disc-shaped part with the same size as the water-cooled copper disc of the directional solidification furnace, such as Figure 1 As shown; Step 2: Wax pressing The chassis wax mold 7, the pouring cup wax mold 8 and the blade wax mold 9 are pressed; wherein the chassis embedded part 1 is embedded in the chassis wax mold 7, and the pouring cup embedded part 3 is embedded in the pouring cup wax mold 8, such as Figure 2 As shown; Step 3: Assemble the model The chassis wax model 7, the pouring cup wax model 8 and the plurality of blade wax models 9 are combined by using a tool to form a module. Figure 2 and Figure 3 As shown; wherein, a plurality of connecting rods 2 are evenly distributed around the outside of the chassis wax mold 7, and the two ends are detachably fixedly connected to the chassis embedded parts 1 and the pouring cup cover plate 4, respectively; the docking screw 5 of the pouring cup embedded parts 3 matches and passes through the center hole of the pouring cup cover plate 4 and is threadedly connected to the T-shaped handle 6; the T-shaped handle 6 abuts against the upper end of the pouring cup cover plate 4; the pouring cup wax mold 8 is close to the pouring cup cover plate 4; the lower end of each blade wax mold 9 is connected to the chassis wax mold 7 through the crystallization section wax mold 10, and the upper end is connected to the pouring cup wax mold through the runner wax mold 11; Step 4, seal the gap between the pouring cup wax mold 8 and the pouring cup cover plate 4 with wax liquid, and brush wax on the surfaces of all parts of the tooling except the T-shaped handle 6; Step 5: The robot clamps or the manual T-handle 6 is used to dip the entire module into slurry, sprinkle sand, and dry it multiple times to form an initial mold shell; Step 6, remove the T-shaped handle 6 and the pouring cup cover 4, invert the entire initial mold shell for dewaxing, remove the other parts of the tooling after the dewaxing is completed, obtain a casting mold shell with a cavity, and wipe and clean the removed tooling for next recycling; Step 7: insert the seed crystal from the bottom of the casting mold into the seed crystal cavity formed after the crystallization wax mold 10 is dewaxed, and then use the casting mold to prepare a single crystal casting.

[0019] The present invention designs a tooling and embeds the chassis embedded part 1 of the tooling in the chassis wax mold 7, and then uses a connecting rod 2 to connect the pouring cup embedded part 3 with the chassis embedded part 1, so as to provide support for the entire module and ensure the strength of the module. The connecting rod 2 is distributed on the outside of the chassis and does not occupy the chassis space. Therefore, the effective mold assembly area is the entire circular area of ​​the chassis. When the blade wax mold 9 is installed, it can be moved closer to the middle of the chassis so that its outer contour does not exceed the range of the entire chassis. The entire module can be smoothly loaded into the furnace to achieve directional casting of large-sized single crystal blades. The present invention realizes the preparation of large-sized single crystal blades by adding a set of mold assembly tooling without modifying the existing directional solidification furnace.

[0020] It is understandable that in actual production, there is a small amount of residual wax in the casting mold cavity after dewaxing. Before pouring, it needs to be roasted to burn off the residual wax, and the strength of the ceramic mold is improved by roasting. During pouring, the casting mold is placed in a directional solidification furnace for alloy pouring. The pouring temperature is about 1500-1550℃. After pouring, it is pulled at a speed of 2-4mm / min until the pulling is completed and it is taken out of the furnace. After air cooling for 2h after being taken out of the furnace, it can be shelled to obtain a large single crystal guide blade casting blank.

[0021] See also Figure 3 In some embodiments, the blade wax mold 9 is formed on the mold in an inclined manner, and the crystallization section wax mold 10 is arranged on the chassis at an angle, and the inclination direction is parallel to the blade body axis of the blade wax mold 9. This design method can effectively avoid the formation of stray crystals on the one hand, and on the other hand, it can ensure the casting's requirements for dendrite orientation.

[0022] In order to improve the strength of the entire module and prevent the wax mold from deforming during the slurry and sanding process, a plurality of ceramic support rods 12 for supporting the blade wax mold 9 are welded on the wax mold chassis.

[0023] See also Figure 1 and Figure 3In some embodiments, the detachable connection structure of the connecting rod 2, the pouring cup cover plate 4 and the chassis embedded part 1 can be adopted as follows: threaded columns 13 are provided at both ends of the connecting rod 2, and the diameter of the threaded column 13 is smaller than the diameter of the connecting rod 2. When assembling the mold, the chassis gasket 14 is first connected to the corresponding threaded hole on the chassis embedded part 1 through the connecting screw, and then the threaded column 13 at the lower end is matched and passed through the connecting hole on the chassis gasket 14 and locked with the locking nut 15, so that the connecting rod 2 is vertically fixed on the chassis embedded part 1. The number of connecting rods 2 can be three, four, or even more. Afterwards, after the docking screw 5 of the pouring cup embedded part 3 is passed through the pouring cup cover plate 4, the T-shaped handle 6 is tightened to make it abut against the pouring cup cover plate 4, and the pouring cup wax mold 8 is suspended and fixed under the pouring cup cover plate 4. Then, the threaded column 13 at the upper end is matched and passed through the connecting hole on the pouring cup cover plate 4 and then locked with the locking nut 15, so that the pouring cup cover plate 4 is clamped and fixed between the locking nut 15 and the connecting rod 2, and the pouring cup cover plate 4 is firmly fixed to the upper end of the connecting rod 2.

[0024] See also Figure 1 In order to improve the bonding strength between the wax material and the chassis embedded part 1, a groove 16 is provided on the upper surface of the chassis embedded part 1. In order to facilitate the inversion of the module for dewaxing, when the initial mold shell is inverted for dewaxing, the dewaxing pad 17 is covered on the initial mold shell, and the threaded column 13 of the connecting rod 2 is matched and passed through the corresponding connecting hole on the dewaxing pad 17 and connected with the locking nut 15. While fixing the dewaxing pad 17, its lower surface is tightly attached to the initial mold shell. A wax discharge hole 18 is provided on the dewaxing pad 17 at the position corresponding to the pouring cup wax mold. After loosening and unscrewing the docking screw 5 from the pouring cup embedded part 3, the entire initial mold shell is inverted, and the dewaxing pad 17 is used to support the initial mold shell for dewaxing. Figure 4 shown.

[0025] The inventors further discovered that during the casting preparation process, for seed crystals of different diameters, it is usually required that 3-4 mm of the top of the seed crystal melt back. This ensures that the seed crystal can be successfully seeded without wasting materials or limiting the space of the wax mold. This is because if the seed crystal inserted into the bottom of the mold shell is too short, it will not melt back during insulation and will only remain solid, and crystal phase transfer cannot be achieved. When the inserted seed crystal is too long, although it can ensure that the top of the seed crystal melts back, there will be problems of limiting the space of the wax mold and wasting materials. In order to quickly determine the seed crystal length required for directional solidification of this model of large single crystal guide blades, the present application proposes the following innovative solution:, which specifically includes the following processes: Determine the seed crystal diameter to be used in directional solidification of the casting according to the casting mold assembly plan; Prepare wax models, such as Figure 5 and Figure 6As shown, each wax mold includes a base plate, a center column tube and a plurality of wax rods of the same size, and the diameter of the wax rods is the same as the diameter of the seed crystal to be used for directional solidification of the casting; Then the wax mold is dipped in slurry and sanded to obtain a preliminary ceramic shell; After that, the preliminary ceramic shell is dewaxed and fired to obtain the experimental shell, such as Figure 7 As shown, the cavity formed after the wax stick is dewaxed constitutes the seed crystal cavity; An experimental seed crystal is matched and inserted into each seed crystal cavity of the experimental mold shell. The length of the experimental seed crystal inserted into each seed crystal cavity is inconsistent. The lower end of each experimental seed crystal is flush with the bottom plate of the mold shell. The side of each experimental seed crystal is degassed to form a channel for the flow of molten metal between the seed crystal cavities. The material of the experimental seed crystal is the same as the seed crystal material to be used in the directional solidification of the casting. The experimental mold shell is then placed in a solidification furnace to simulate the actual pouring process of the casting; After the experiment, the shell is removed, the experimental seed crystal is cleaned, and the surface state of the experimental seed crystal is observed and recorded. If the temperature at the top of the seed crystal reaches below the liquidus temperature, the top surface and the degassed surface of the seed crystal are flat, which is equivalent to a heat treatment. If the temperature at the top of the seed crystal reaches above the liquidus temperature, the seed crystal starts to melt back from the top, the top surface is uneven, and the molten alloy liquid will flow along the gap between the seed crystal cavity and the degassed surface of the seed crystal, and solidify on the degassed surface of the seed crystal during subsequent pulling, forming an obvious seam layer. Therefore, it is possible to infer and predict whether there will be any meltback during mold casting based on the surface state of the seed crystal. Then, the seed crystal with alloy liquid flowing on the measuring surface will be axially sectioned, and the section surface will be polished and corroded to observe the metallographic structure, and the meltback interface of the experimental seed crystal will be determined. Then, the length L from the meltback interface to the bottom of the experimental seed crystal will be measured, and the length L will be subtracted from the original length of the seed crystal to obtain the length of the seed crystal meltback section. The shortest length required for effective seeding is determined by comparing the meltback conditions of seed crystals at different heights, and the experimental seed crystal with a seed crystal meltback section length of 3-4mm (that is, the shortest length seed crystal required for effective seeding) is used to prepare castings.

[0026] The present invention prepares a high-throughput experimental mold shell and obtains multiple groups of seed crystal melt-back data at different heights through a single directional solidification experiment. Then, by sectioning the experimental seed crystal and polishing and corroding the section surface to observe the metallographic structure, the melt-back interface of the experimental seed crystal can be determined, and the shortest length required for effective seed crystal induction can be quickly determined.

[0027] When preparing the experimental mold shell, the wax mold does not require a pouring system, which reduces the difficulty of mold assembly, and does not need to prepare the master alloy before the experiment, which reduces the pouring cost. At the same time, compared with the usual pouring, the experiment saves the time of heating, melting and pouring the master alloy, and the pulling distance is short, which shortens the experimental time. By removing the amount from the side of the seed crystal, a flow surface for the molten metal to flow is formed, so there is no need to grind and corrode the cross section of the seed crystal to observe the metallographic structure to judge the remelting situation. Only by comparing the surface state of the removed surface of the seed crystal at different heights, it can be quickly determined whether the seed crystal has remelted. When the seed crystal remelting length is determined, the number of experimental seed crystal sections can be greatly reduced.

[0028] Specifically, by changing the wax rod size of the wax mold and the alloy type of the seed crystal and repeating the above process, the actual pouring process of seed crystals of different heights, different diameters and different alloy types can be simulated.

[0029] Unless otherwise stated, any technical solution disclosed in the present invention disclosed above, if it discloses a numerical range, then the disclosed numerical range is a preferred numerical range, and any technician in the field should understand that the preferred numerical range is only a numerical value with a more obvious technical effect or representative value among many implementable numerical values. Since there are too many numerical values ​​to be exhaustive, the present invention discloses some numerical values ​​to illustrate the technical solution of the present invention, and the numerical values ​​listed above should not constitute a limitation on the scope of protection of the present invention.

[0030] At the same time, if the above-mentioned invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connected by bolts or screws), and can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integrated structure (for example, manufactured by one-piece molding using a casting process) (except when it is obviously impossible to use an one-piece molding process).

[0031] In addition, the terms used in any technical solution disclosed in the present invention to indicate positional relationships or shapes include states or shapes that are similar, similar or close to them unless otherwise stated. Any component provided by the present invention may be assembled from multiple separate components or may be a separate component manufactured by an integrated molding process.

[0032] The above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a large single crystal guide blade, characterized in that: The steps include: Step 1, making a tooling, which includes a chassis embedded part, a connecting rod, a pouring cup embedded part, a pouring cup cover plate and a T-shaped handle; Step 2: Wax pressing Pressing a chassis wax mold, a pouring cup wax mold and a blade wax mold; wherein the chassis embedded parts are embedded in the chassis wax mold, and the pouring cup embedded parts are embedded in the pouring cup wax mold; Step 3: Assemble the model The chassis wax model, the pouring cup wax model and a plurality of blade wax models are combined by using tooling to form a module; wherein a plurality of connecting rods are evenly distributed around the outside of the chassis wax model, and the two ends are detachably fixedly connected to the chassis embedded parts and the pouring cup cover plate respectively, the docking screw of the pouring cup embedded parts matches and passes through the center hole of the pouring cup cover plate and is threadedly connected to the T-handle, the T-handle abuts against the upper end of the pouring cup cover plate, the pouring cup wax model is close to the pouring cup cover plate, the lower end of each blade wax model is connected to the chassis wax model through the crystallization section wax model, and the upper end is connected to the pouring cup wax model through the runner wax model; Step 4: Seal the gap between the pouring cup wax mold and the pouring cup cover with wax liquid, and brush wax on the surfaces of all parts of the tooling except the T-shaped handle; Step 5: The entire module is clamped by a robot or manually held by a T-shaped handle, and the entire module is dipped in slurry, sprinkled with sand, and dried multiple times to form an initial mold shell; Step 6: Remove the T-shaped handle and the pouring cup cover, invert the entire initial mold shell for dewaxing, and after dewaxing is completed, remove the other parts of the tooling to obtain a casting mold shell with a cavity; Step 7: Insert the seed crystal from the bottom of the casting mold into the seed crystal cavity formed after the wax mold of the crystallization section is dewaxed, and then use the casting mold to prepare a single crystal casting.

2. The method for preparing a large single crystal guide blade according to claim 1, characterized in that: The blade wax mold is formed on the mold set in an inclined manner, and the crystallization section wax mold is arranged on the chassis wax mold in an inclined direction, and the inclined direction is parallel to the blade body axis of the blade wax mold.

3. The method for preparing a large single crystal guide blade according to claim 1 or 2, characterized in that: A plurality of ceramic support rods for supporting the blade wax model are welded on the wax model chassis.

4. The method for preparing a large single crystal guide blade according to claim 1 or 2, characterized in that: Threaded columns are provided at both ends of the connecting rod, and the diameter of the threaded columns is smaller than the diameter of the connecting rod. When assembling the mold, the chassis gasket is first connected to the corresponding threaded holes on the chassis embedded parts through the connecting screws, and then the threaded columns at the lower end are matched and passed through the connecting holes on the chassis gasket and locked with locking nuts. After that, the docking screws of the pouring cup embedded parts are passed through the pouring cup cover plate, and the T-shaped handle is tightened to make it abut against the pouring cup cover plate, and the pouring cup wax mold is suspended and fixed under the pouring cup cover plate. Then, the threaded columns at the upper end are matched and passed through the connecting holes on the pouring cup cover plate and locked with locking nuts to fix the pouring cup cover plate to the upper end of the connecting rod.

5. The method for preparing a large single crystal guide blade according to claim 1 or 2, characterized in that: The upper surface of the chassis embedded part is provided with a groove.

6. The method for preparing a large single crystal guide blade according to claim 1 or 2, characterized in that: There is a small amount of residual wax in the casting mold cavity after dewaxing, and it needs to be calcined before pouring to burn off the residual wax.

7. The method for preparing a large single crystal guide blade according to claim 6, characterized in that: (8) The casting mold shell is placed in a directional solidification furnace for alloy casting at a pouring temperature of about 1500-1550°C. After casting, the casting mold shell is pulled at a speed of 2-4 mm / min until the casting is completed and the casting is taken out of the furnace. After being air-cooled for 2 hours, the casting mold shell is removed to obtain a large single crystal guide blade casting.

8. The method for preparing a large single crystal guide blade according to claim 1 or 2, characterized in that: When the initial mold shell is inverted for dewaxing, the dewaxing pad is covered on the initial mold shell, and the threaded column of the connecting rod is matched and passed through the corresponding connecting hole on the dewaxing pad and then connected to the locking nut. While fixing the dewaxing pad, its lower surface is tightly attached to the initial mold shell. A wax drainage hole is provided on the dewaxing pad at the position of the pouring cup wax mold. After loosening and unscrewing the docking screw from the pouring cup embedded part, the entire initial mold shell is inverted, and the dewaxing pad is used to support the initial mold shell for dewaxing.

9. The method for preparing a large single crystal guide blade according to claim 1 or 2, characterized in that: The following steps are also included: Determine the seed crystal diameter to be used in directional solidification of the casting according to the casting mold assembly plan; Prepare wax molds, each wax mold includes a base plate, a center column tube and a number of wax rods of the same size, the diameter of the wax rods being the same as the diameter of the seed crystal to be used for directional solidification of the casting; Then the wax mold is dipped in slurry and sanded to obtain a preliminary ceramic shell; Afterwards, the preliminary ceramic shell is dewaxed and fired to obtain an experimental shell, and the cavity formed after the wax rod is dewaxed constitutes the seed crystal cavity; An experimental seed crystal is matched and inserted into each seed crystal cavity of the experimental mold shell. The length of the experimental seed crystal inserted into each seed crystal cavity is inconsistent. The lower end of each experimental seed crystal is flush with the bottom plate of the mold shell. The side of each experimental seed crystal is degassed to form a channel for the flow of molten metal between the seed crystal cavities. The material of the experimental seed crystal is the same as the seed crystal material to be used in the directional solidification of the casting. The experimental mold shell is then placed in a solidification furnace to simulate the actual pouring process of the casting; After the experiment, the shell was removed, the experimental seed crystal was cleaned, and the surface state of the experimental seed crystal was observed and recorded. The seed crystal with alloy liquid flowing on the measured surface was axially sectioned, and the section surface was polished and corroded to observe the metallographic structure, and the remelting interface of the experimental seed crystal was determined. Then, the length from the remelting interface to the bottom of the experimental seed crystal was measured, and the original length of the seed crystal was subtracted from this length to obtain the length of the seed crystal remelting section. The experimental seed crystal with a seed crystal remelting section length of 3-4mm was used to prepare the final casting.

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