A method for manufacturing a single crystal casting and a mold for the same

Abstract

The application relates to the technical field of single-crystal alloy, in particular to a fused mold and a single-crystal casting preparation method. Specifically, the fused mold comprises a mold body, a first cavity in the mold body is used for injecting molten wax, and the mold body is made of a material with a melting point higher than 150 DEG C, 200 DEG C, 250 DEG C or 500 DEG C; a first through hole in communication with the first cavity is arranged on the mold body, so that the first cavity is in communication with the outside of the mold body; and a second through hole in communication with the first cavity is arranged on the mold body and has a seed crystal inlet away from the first cavity and a seed crystal outlet close to the first cavity. According to the technical scheme, the second through hole is arranged to make the seed crystal extend into the first cavity, the relative positional relationship between the seed crystal and the first cavity is ensured, the axial direction of the seed crystal is kept consistent with the axial direction of the second through hole, a better quality mold shell is obtained, and a single-crystal casting with better crystal orientation precision is prepared.

Description

Technical Field

[0001] This application relates to the field of single crystal alloy technology, specifically to an investment mold and a method for preparing single crystal castings. Background Technology

[0002] The main methods for fabricating single-crystal blades include the selective crystal method and the seed crystal method. However, the traditional selective crystal method results in random crystal orientation, and deviations in orientation can severely affect the high-temperature mechanical properties of the blades, thus limiting engine performance to some extent. The seed crystal method allows for precise control of crystal orientation in any direction, reducing the scrap rate and improving the performance of single-crystal blades; however, its high manufacturing complexity limits its current engineering applications. Therefore, it is essential to improve and optimize existing technologies.

[0003] Therefore, there is an urgent need in the field for an investment mold and a method for preparing single crystal castings that can solve the above problems, hence this application is proposed.

[0004] Application content

[0005] The purpose of this application is to provide an investment mold and a method for preparing single crystal castings to solve at least one of the technical problems described in the background art.

[0006] Specifically, in the first aspect of this application, an investment mold is provided for preparing single-crystal castings, comprising:

[0007] The mold body has a first cavity inside for injecting molten wax. The mold body is made of a material with a melting point higher than 150°C, 200°C, 250°C, or 500°C.

[0008] A first through hole communicating with the first cavity, wherein the first through hole is opened on the mold body, so that the first cavity communicates with the outside of the mold body;

[0009] A second through hole communicating with the first cavity is opened on the mold body. The second through hole has a seed crystal inlet away from the first cavity and a seed crystal outlet close to the first cavity. The second through hole is used to place the seed crystal that cooperates with it. When the seed crystal penetrates into the first cavity through the seed crystal outlet to a first distance, it does not contact the inner wall of the opposite side of the first cavity.

[0010] By adopting the above technical solution, the seed crystal is inserted into the first cavity by setting a second through hole, which ensures the relative orientation relationship between the seed crystal and the first cavity, and makes the axial direction of the seed crystal consistent with the axial direction of the second through hole, so as to obtain a mold shell with better quality, thereby producing a single crystal casting with better crystal orientation accuracy.

[0011] Preferably, the first through hole and the second through hole are disposed on opposite sides of the mold body.

[0012] Preferably, the cross-sectional area of ​​the first through hole is smaller than the cross-sectional area of ​​the second through hole.

[0013] Preferably, the inner wall of the second through hole is provided with an anti-wear layer to reduce the wear of the seed crystal when it enters the second through hole.

[0014] Preferably, the investment mold is provided with a guide block, which is located at the seed crystal entrance and is used to adjust the relative orientation between the seed crystal and the first cavity.

[0015] Preferably, the guide block includes a first guide block and a second guide block, which are respectively disposed on the slide rail so that the first guide block and the second guide block can move in a direction perpendicular to the extension direction of the second through hole.

[0016] Preferably, the inner wall of the guide block is provided with a guide groove or guide rib parallel to the direction of seed crystal movement.

[0017] A second aspect of this application provides a pre-set seed crystal investment mold for preparing single-crystal castings, comprising:

[0018] As described in the first aspect of this application, the investment mold

[0019] The seed crystal has a first end and a second end along its length. The seed crystal is disposed within a second through hole, and its first end extends into the first cavity by a first distance.

[0020] The wax fills the first cavity.

[0021] Preferably, a flexible layer is provided on the outside of the seed crystal, and the flexible layer does not enter the interior of the first cavity.

[0022] Preferably, the outer wall of the seed crystal is covered with a first non-metallic layer, and the roughness of the first non-metallic layer is greater than that of the seed crystal.

[0023] Preferably, the second end of the seed crystal is not covered by the first non-metallic layer.

[0024] Preferably, the first non-metallic layer is a paraffin layer.

[0025] A third aspect of this application provides a method for preparing a single-crystal casting, comprising the steps of:

[0026] Insert a seed crystal, insert the seed crystal into the investment mold as described in the first aspect of this application through the second through hole, and the seed crystal penetrates into the first cavity by a first distance;

[0027] Wax material is injected into the investment mold through the first through hole to obtain the investment mold with the pre-set seed crystal. When the wax material is injected through the first through hole, the wax material will not seep out from the second through hole.

[0028] Prepare the mold shell by using the investment casting shell-making process to prepare the casting mold shell and obtain the mold shell with pre-placed seed crystal;

[0029] To prepare a single crystal casting, the mold shell of the pre-placed seed crystal is used to prepare the single crystal casting.

[0030] Preferably, the step of preparing the single-crystal casting includes:

[0031] The pre-set seed crystal mold is placed in a directional solidification furnace. The holding temperature of the single crystal furnace is adjusted to 1450-1550℃. After holding for 2-30 minutes, high-temperature alloy liquid is poured in and left to stand for 2-20 minutes. Then, it is pulled downwards at a speed of 20-200μm / s. After the crystal pulling is completed, it is taken out after the heating furnace cools down to obtain a single crystal casting.

[0032] Preferably, the method for preparing the single-crystal casting further includes the step of:

[0033] The seed crystal is coated with wax. The seed crystal is then immersed in the molten wax and kept for 1-10 seconds before being removed from the wax and cooled. The length of the seed crystal not coated with wax is between 3-15 mm, and the thickness of the wax coating on the seed crystal surface is 0.01-0.25 mm.

[0034] Preferably, the method for preparing the single-crystal casting further includes the step of:

[0035] The seed crystal with wax coating on its surface is fitted with a flexible layer and placed in the second through hole, ensuring that the end without wax coating is located away from the first cavity.

[0036] Preferably, the method for preparing the single-crystal casting further includes the step of:

[0037] The guide block is pressed down to make the seed crystal axis parallel to the seed crystal segment axis in the mold. Wax material is injected into the mold through the first through hole to obtain a casting mold with a pre-placed seed crystal.

[0038] In summary, this application has the following beneficial effects:

[0039] 1. The investment mold provided in this application allows the seed crystal to extend into the first cavity by setting a second through hole. The position of the seed crystal is limited by the anti-wear layer and the guide block to ensure the orientation relationship between the seed crystal and the first cavity, thereby producing single crystal castings with more precise orientation control and higher yield.

[0040] 2. The investment mold with pre-set seed crystal provided in this application ensures the integrity of the seed crystal by setting a first non-metallic layer on the outside of the seed crystal and cooperating with the anti-wear layer of the mold. At the same time, it can avoid the influence of the seed crystal surface on the subsequent shell-making process. Furthermore, the first non-metallic layer can be melted when preparing single crystal castings, which simplifies the single crystal casting production process and improves the success rate of single crystal casting preparation.

[0041] 3. The method for preparing single crystal castings provided in this application can produce single crystal castings with more precise orientation control and higher yield by using the mold provided in this application to prepare the mold shell, thereby reducing the overall cost of single crystal castings. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of a casting mold in one embodiment of this application;

[0044] Figure 2 This is a schematic diagram of the investment mold after the seed crystal is placed in one embodiment of this application;

[0045] Figure 3 This is a schematic diagram of removing the wax casting mold after wax is injected, according to one embodiment of this application.

[0046] Figure 4 This is a schematic diagram showing the seed crystal through-hole formed by the first guide block and the second guide block in one embodiment of this application;

[0047] Figure 5 This is a front view of a guide block in one embodiment of this application;

[0048] Figure 6 This is a bottom view of the guide block in one embodiment of this application;

[0049] Figure 7 This is a top view of the guide block in one embodiment of this application.

[0050] The attached figures are labeled as follows:

[0051] 1. First cavity; 2. First through hole; 3. Second through hole; 31. Seed crystal inlet; 32. Seed crystal outlet; 33. Anti-wear layer; 4. Seed crystal; 41. Boss; 42. First end; 43. Second end; 44. First non-metallic layer; 5. Guide block; 51. First guide block; 52. Second guide block; 53. Guide groove; 6. Slide rail; 7. Seed crystal through hole. Detailed Implementation

[0052] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0053] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0054] To address the technical problems existing in the preparation of single-crystal blades in the background art, the inventive concept of this application is to provide an investment mold for preparing single-crystal castings, comprising: a mold body having a first cavity for injecting molten wax, the mold body being made of a material with a melting point higher than 150℃, 200℃, 250℃, or 500℃; a first through hole communicating with the first cavity, the first through hole being formed on the mold body to connect the first cavity with the outside of the mold body; and a second through hole communicating with the first cavity, the second through hole being formed on the mold body, having a seed crystal inlet away from the first cavity and a seed crystal outlet close to the first cavity, the second through hole being used to place a seed crystal that mates with it, and when the seed crystal penetrates into the first cavity through the seed crystal outlet to a first distance, it does not contact the opposite inner wall of the first cavity. According to this inventive concept, by setting the second through hole to allow the seed crystal to extend into the first cavity, the direction of seed crystal growth is guided, resulting in single-crystal castings with better performance and higher yield.

[0055] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0056] The present application will be described in detail below through examples.

[0057] In some preferred embodiments of this application, reference is made to Figures 1-3A casting mold is provided, comprising: a mold body having a first cavity 1 for injecting molten wax, wherein the mold body is made of a material with a melting point higher than 150°C, 200°C, 250°C, or 500°C; a first through hole 2 communicating with the first cavity, the first through hole 2 being formed on the mold body to connect the first cavity 1 with the outside of the mold body; and a second through hole 3 communicating with the first cavity 1, the second through hole 3 being formed on the mold body, having a seed crystal inlet 31 away from the first cavity 1 and a seed crystal outlet 32 ​​close to the first cavity 1, the second through hole 3 being used to place a seed crystal 4 that cooperates with it, and when the seed crystal 4 penetrates into the first cavity 1 through the seed crystal outlet 32 ​​to a first distance, it does not contact the opposite inner wall of the first cavity 1.

[0058] In specific implementation, the mold body can be selected from materials with melting points higher than 150℃, 200℃, 250℃, or 500℃, such as elemental metals like iron and copper, or metal-containing mixtures like stainless steel, cast iron, and carbon steel; wherein, the shape of the first cavity 1 of the mold body corresponds to the single crystal casting to be produced, such as blades, and is used to fill the mold material such as paraffin wax; the first through hole 2 has a smaller diameter and communicates with the first cavity 1, used for injecting paraffin wax from the outside; the second through hole 3 is used to insert and fix the seed crystal. In some embodiments, the second through hole 3 and the first through hole 1 are located on opposite sides of the mold body to facilitate the injection and shaping of paraffin wax; see reference. Figure 2 Seed crystal 4 enters the first cavity 1 through the second through hole 3, forming a boss 41 for crystal growth in subsequent processes.

[0059] By adopting the above technical solution, the seed crystal 4 is inserted into the first cavity 1 by setting the second through hole 3, ensuring the relative orientation relationship between the seed crystal 4 and the first cavity 1, and keeping the axial direction of the seed crystal 4 consistent with the axial direction of the second through hole 3, so as to obtain a mold shell with better quality, thereby producing a single crystal casting with better crystal orientation accuracy.

[0060] In some preferred embodiments, the cross-sectional area of ​​the first through hole 2 is smaller than that of the second through hole 3. In specific implementations, the diameter of the first through hole 2 can be less than half that of the second through hole 3 to facilitate mold production and improve the effect of paraffin wax injection.

[0061] In some preferred embodiments, an anti-wear layer 33 is provided on the inner wall of the second through hole 3 to reduce the wear of the seed crystal 4 when it enters the second through hole 3.

[0062] In specific implementation, the wear-resistant layer 33 can be made of elastic material, such as rubber or latex, and fixed to the inner wall of the second through hole 3. The fixing method can be bonding. In some embodiments, the wear-resistant layer 33 can be a wear-resistant ring made of elastic material and disposed on the inner wall of the second through hole 3.

[0063] By adopting the above technical solution and setting the anti-wear layer 33, on the one hand, the seed crystal 4 can be more tightly bonded to the second through hole 3, and on the other hand, the friction experienced by the seed crystal 4 when it extends into the first cavity 1 from the second through hole 3 can be reduced, thus ensuring the integrity of the seed crystal 4.

[0064] In some preferred embodiments, reference Figures 4-7 The investment mold is equipped with a guide block 5, which is located at the seed crystal entrance and is used to adjust the relative orientation between the seed crystal 4 and the first cavity 1. In specific implementation, the guide block includes a first guide block 51 and a second guide block 52, which are respectively mounted on the slide rail 6 so that the first guide block 51 and the second guide block 52 can move in a direction perpendicular to the extension direction of the second through hole 3 and form the seed crystal through hole 7.

[0065] In specific implementation, the slide rail 6 is fixedly installed at one end of the mold body where the second through hole 3 is located. The first guide block 51 and the second guide block 52 are slidably installed on the slide rail 6. The user can adjust the size of the seed crystal through hole 7 by adjusting the distance between the first guide block 51 and the second guide block 52 to guide the seed crystal 4 so that the seed crystal 4 can enter the first cavity 1 at a suitable angle, thereby adjusting the relative orientation relationship between the seed crystal 4 and the first cavity 1 and ensuring the accuracy of crystal growth orientation in subsequent processes. In some embodiments, the end of the slide rail 6 near the second through hole 3 has a limiting platform to limit the movement range of the first guide block 51 and the second guide block 52.

[0066] In some embodiments, reference Figures 5-7 The inner walls of the first guide block 51 and the second guide block 52 are provided with guide grooves 53 or guide ribs parallel to the moving direction of the seed crystal 4, which are used to cooperate with the ribs or grooves of the slide rail 6 to limit the first guide block 51 and the second guide block 52.

[0067] In some embodiments, reference Figures 5-7 The first guide block 51 and the second guide block 52 are provided with protruding ribs 54 on the surfaces away from the mold body. The protruding ribs 54 extend from the opening of the slide rail 6 and are used by the user to apply force to move the first guide block 51 and the second guide block 52, which facilitates operation in production.

[0068] In some other embodiments of this application, a pre-set seed crystal investment mold is provided for preparing single crystal castings, comprising: an investment mold as described in the above embodiments; a seed crystal 4 having a first end 42 and a second end 43 in its length direction, the seed crystal 4 being disposed in a second through hole 3, and its first end 42 extending into a first cavity by a first distance; and wax material filling the first cavity 1.

[0069] In specific implementation, the seed crystal 4 can be in the shape of a cylinder, cuboid, etc., and can match the shape of the second through hole 3.

[0070] By adopting the above technical solution, by setting a second through hole 3, the first end 42 of the seed crystal 4 is allowed to extend into the first cavity 1, thereby guiding the growth direction of the seed crystal 4 and producing a single crystal casting with better performance and higher yield.

[0071] In some preferred embodiments, a flexible layer is fitted over the seed crystal 4, and this flexible layer does not enter the interior of the first cavity 1. Specifically, the flexible layer can be made of flexible materials such as rubber or latex to prevent damage to the seed crystal 4. At the same time, placing the flexible layer outside the first cavity 1 can reduce the influence of the flexible material on the paraffin wax shaping and ensure the completion of the process.

[0072] In some preferred embodiments, reference Figures 1-3 The seed crystal outer wall is covered with a first non-metallic layer 44. The first non-metallic layer 44 can create a gap between the mold shell and the seed crystal 4, thereby improving the accuracy of crystal orientation control in the single crystal casting. On the other hand, the gap between the mold shell and the seed crystal 4 can also prevent the mold shell from being compressed and cracked during subsequent manufacturing processes. Furthermore, the roughness of the first non-metallic layer 44 is greater than that of the seed crystal, so as to increase the friction coefficient between the seed crystal 4 and the inner wall of the second through hole 3, so that it can more stably guarantee the crystal growth angle.

[0073] In specific implementation, the wetting angle between the first non-metallic layer material and the seed crystal in the molten state is not less than 90°, and the melting point of the first non-metallic layer material is lower than that of the seed crystal material. The wetting angle usually refers to the angle between the liquid-solid interface and the tangent of the liquid surface at the contact point between the liquid and solid phases. After a large number of experiments, the applicant unexpectedly discovered that when the wetting angle between the first non-metallic layer outside the seed crystal body in the molten state and the seed crystal is not less than 90°, it can make the surface of the seed crystal easier to coat with slurry during shell making, thereby ensuring the excellent performance of the seed crystal segment mold shell after shell making. In some embodiments, the material of the first non-metallic layer 44 can be a material with a melting point not exceeding 200°, such as paraffin wax or palm wax; in some embodiments, the second end 43 of the seed crystal 4 is not covered by the first non-metallic layer.

[0074] In some preferred embodiments, the second end 43 of the seed crystal is not covered by the first non-metallic layer 44. Specifically, the area of ​​the seed crystal 4 not covered by the first non-metallic layer 44 can be no less than 1 / 10 of the total length of the seed crystal 4, and no more than 1 / 2 of the total length. By adopting the above technical solution, the portion of the seed crystal 4 not covered by the first non-metallic layer 44 can facilitate the operation of clamping the seed crystal 4, and can also avoid damage to the first non-metallic layer 44 by the guide block 5 when fixing the seed crystal 4.

[0075] In other embodiments of this application, a method for preparing a single-crystal casting is provided, comprising the steps of:

[0076] S301, Insert seed crystal 4. Insert seed crystal 4 into the investment mold as described in the above embodiment through the second through hole 3, and the seed crystal 4 penetrates into the first cavity 1 by a first distance.

[0077] In specific implementation, the seed crystal 4 can be in the shape of a cylinder, cuboid, etc., and can match the shape of the second through hole 3.

[0078] S401, Inject wax material. The wax material is injected into the casting mold through the first through hole 2 to obtain the casting mold with the pre-set seed crystal. When the wax material is injected through the first through hole 2, the wax material will not seep out from the second through hole 3.

[0079] In the specific implementation process, the wax is in a molten state, but since the first non-metallic layer 44 on the surface of the seed crystal 4 is paraffin wax, the first non-metallic layer 44 will not melt when the wax is injected into the investment mold. In addition, since the investment mold has an anti-wear layer 33, the seed crystal 4 can seal the second through hole 3 so that the wax will not seep out from the second through hole 3, thus ensuring the stability of the mold when the wax is injected.

[0080] S501, Prepare the mold shell. Use the investment casting shell-making process to prepare the casting mold shell and obtain the mold shell with pre-placed seed crystal.

[0081] In the specific implementation process, the investment mold is removed, and the investment mold with the pre-set seed crystal is used to make a shell according to the standard shell making process, thereby obtaining the shell of the pre-set seed crystal.

[0082] S601, Prepare a single crystal casting by using the pre-placed seed crystal mold shell.

[0083] In the specific implementation process, the pre-set seed crystal mold shell obtained in step S501 is used to prepare single crystal castings, so that the casting material grows in a single phase from the seed crystal to obtain finished single crystal castings. These castings can be used for products such as engine blades that have higher requirements for crystal orientation.

[0084] In some preferred embodiments, the steps for preparing the single crystal casting include: placing the pre-set seed crystal mold shell into a directional solidification furnace, adjusting the holding temperature of the single crystal furnace to 1450-1550℃, holding for 2-30 minutes, pouring in high-temperature alloy liquid, letting it stand for 2-20 minutes, and then pulling it downwards at a speed of 20-200μm / s. After the crystal pulling is completed, the casting is removed after the heating furnace has cooled down to obtain the single crystal casting.

[0085] In some preferred embodiments, the method for preparing the single-crystal casting further includes the step of:

[0086] S101, the seed crystal surface is coated with wax, the seed crystal part is immersed in the molten wax, and after holding for 1-10 seconds, it is taken out of the wax and cooled. The length of the seed crystal not coated with wax is between 3-15mm, the thickness of the wax on the seed crystal surface is 0.01-0.25mm, which is the first non-metallic layer, and the end not coated with wax is the second end of the seed crystal.

[0087] In some preferred embodiments, the method for preparing the single-crystal casting further includes the step of:

[0088] S102, the seed crystal with wax coating on its surface is fitted with a flexible layer and placed in the second through hole 3, ensuring that the end without wax coating is located on the side away from the first cavity 1.

[0089] In some preferred embodiments, the method for preparing the single-crystal casting further includes the step of:

[0090] S302, tighten the guide block to make the seed crystal axis parallel to the seed crystal segment axis in the mold, i.e., the extension direction of the second through hole 3. Inject the wax material into the mold through the first through hole to obtain the investment mold with the pre-placed seed crystal.

[0091] In the specific implementation process, after preparing the investment mold, the investment mold containing the seed crystal is removed, and a mold shell matching its structure is prepared based on the investment mold. After obtaining the mold shell, heating is used to melt the investment mold and the first non-metallic layer surrounding the seed crystal, and the liquid wax and the first non-metallic layer material are removed. Due to the melting of the first non-metallic layer material, there will be a certain gap between the seed crystal and the mold shell at this time, which improves the stability of the mold shell when the seed crystal expands due to heat and prevents the mold shell from cracking. Based on this, a mold shell with a seed crystal is prepared, and metal material is poured to prepare a single crystal casting to obtain the finished product. According to the applicant's experimental results, in this embodiment, the thickness of the first non-metallic layer outside the seed crystal body is directly related to the success rate of single crystal preparation and the success rate of crystal orientation control. Detailed data are shown in Table 1.

[0092] Table 1. Relationship between the thickness of the first non-metallic layer and product quality.

[0093]

[0094] Based on the results in Table 1, the applicant unexpectedly discovered the following: First, if no first non-metallic layer is formed on the seed crystal surface, the orientation control success rate will be lower; however, if the thickness of the first non-metallic layer is too large, it will seriously affect the orientation success rate. Second, an excessively thick first non-metallic layer will also reduce the success rate of single crystal preparation, leading to a decrease in yield. Therefore, based on the experimental results in Table 1, the first non-metallic layer thickness should be between 0.01 and...

[0095] Within the range of 0.25 mm, there is a good impact on the success rate of single crystal preparation and the success rate of orientation control, while within the range of 0.08-0.19 mm, the success rate is higher and more stable.

[0096] It should be noted that, for those skilled in the art, the technical features in the above embodiments can be freely combined, and the resulting technical solutions also belong to the embodiments disclosed in this application.

[0097] Furthermore, without departing from the principles of this application, several improvements and modifications may be made to this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. An investment mold for preparing single-crystal castings, characterized in that, include: The mold body has a first cavity inside for injecting molten wax, and the mold body is made of a material with a melting point higher than 150°C; A first through hole communicating with the first cavity, wherein the first through hole is opened on the mold body, so that the first cavity communicates with the outside of the mold body; A second through hole communicating with the first cavity is opened on the mold body. The second through hole has a seed crystal inlet away from the first cavity and a seed crystal outlet close to the first cavity. The second through hole is used to place the seed crystal that cooperates with it. When the seed crystal penetrates into the first cavity through the seed crystal outlet to a first distance, it does not contact the inner wall of the opposite side of the first cavity. The investment mold is equipped with a guide block, which is located at the seed crystal entrance and is used to adjust the relative orientation between the seed crystal and the first cavity.

2. The investment mold according to claim 1, characterized in that: The first through hole and the second through hole are arranged opposite each other on both sides of the mold body.

3. The investment mold according to claim 1, characterized in that: The cross-sectional area of ​​the first through hole is smaller than the cross-sectional area of ​​the second through hole.

4. The investment mold according to claim 1, characterized in that: The inner wall of the second through hole is provided with an anti-wear layer to reduce the wear of the seed crystal when it enters the second through hole.

5. The investment mold according to claim 1, characterized in that: The guide block includes a first guide block and a second guide block, which are respectively disposed on the slide rail so that the first guide block and the second guide block can move in a direction perpendicular to the extension direction of the second through hole.

6. The investment mold according to claim 1, characterized in that: The mold body is made of a material with a melting point higher than 500℃.

7. A pre-set seed crystal investment mold for preparing single crystal castings, characterized in that, include: The investment mold as described in any one of claims 1-6, A seed crystal is disposed within the second through hole and extends into the first cavity by a first distance. The wax fills the first cavity.

8. The investment casting mold for the pre-placed seed crystal according to claim 7, characterized in that: The seed crystal is covered with a flexible layer, and the flexible layer does not enter the first cavity.

9. The investment mold for pre-placed seed crystals according to claim 7, characterized in that: The outer wall of the seed crystal is provided with a first non-metallic layer, and the roughness of the first non-metallic layer is greater than that of the seed crystal.

10. A method for preparing a single-crystal casting, characterized in that, Including the following steps: Insert a seed crystal, insert the seed crystal into the investment mold as described in any one of claims 1-6 through the second through hole, and the seed crystal penetrates into the first cavity by a first distance; Wax material is injected into the investment mold through the first through hole to obtain the investment mold with the pre-set seed crystal. When the wax material is injected through the first through hole, the wax material will not seep out from the second through hole. Prepare the mold shell by using the investment casting shell-making process to prepare the casting mold shell and obtain the mold shell with pre-placed seed crystal; To prepare a single crystal casting, the mold shell of the pre-placed seed crystal is used to prepare the single crystal casting.

Images