A wax removal structure for improving the quality of a lifting mold shell and a preparation method of the mold shell

Abstract

The present application belongs to the technical field of investment precision casting, and particularly relates to a wax removal structure for improving the quality of a shell and a preparation method of the shell. The present application standardizes the design of the wax removal hole and the matched sealing plug, so that the working surface is a smooth and tight ceramic surface, successfully avoiding the problem of secondary inclusion of the shell cavity caused by the traditional wax removal hole and its sealing mode, and effectively improving the quality of the shell for investment precision casting. The present application effectively solves the problem of uneven end surface of the shell after opening of the traditional wax removal hole part, the uneven adhesion strength of the refractory material, and the problems of aluminum foil ash falling off and rough mixed refractory mud exposure in the traditional repair method, which easily causes secondary inclusion. The preparation method of the present application is simple and easy to operate, reduces the uncertainty caused by operation differences and other factors in the product shell cleaning and sealing operation process, greatly improves the production efficiency of the product shell, and thus achieves the purpose of reducing cost and increasing benefit.

Description

Technical Field

[0001] This invention belongs to the field of investment casting technology, specifically relating to a wax removal structure for improving the quality of the mold shell and a method for preparing the mold shell. Background Technology

[0002] With the rapid development of my country's aviation and aerospace industries, various complex silica sol-molded investment castings have been widely used in the manufacturing of aviation and aerospace engines. Because these components often operate under harsh conditions such as high temperature, high pressure, and high corrosion, stringent requirements are placed on their internal and surface quality performance indicators. Furthermore, repair of any type of defect is not permitted, and product acceptance is conducted with a near-zero-defect standard.

[0003] One of the core aspects of achieving qualified production of such components using investment casting is the proper fabrication of the silica sol shell. A high-quality silica sol shell must be free of microcracks. This is because microcracks will directly lead to the peeling off of the surface layer on the inner surface of the shell, allowing various tiny particles to be placed inside the shell cavity. Since these components have complex structures and are mostly thin-walled, it is difficult for these tiny particles to be expelled from the shell cavity, resulting in surface or internal inclusion defects in the casting after pouring. This leads to product defects and severely reduces the product qualification rate. To address this issue, on the one hand, multiple wax drainage holes are used to reduce the expansion of the mold shell caused by the high-temperature, high-pressure steam during dewaxing, which prevents the wax from being discharged in time and thus avoids micro-cracks in the mold shell. On the other hand, multiple wax drainage holes provide multiple channels for subsequent cleaning of foreign matter residue inside the mold shell cavity. In other words, the wax drainage holes also serve the function of cleaning and removing impurities from the mold shell cavity, which is conducive to the thorough cleaning of the mold shell cavity. By addressing both the prevention of mold shell expansion and the facilitation of mold shell cavity cleaning, the probability of casting defects can be significantly reduced, and the casting qualification rate can be improved.

[0004] Traditional wax removal holes are simple cylindrical wax blocks, which are pasted onto various parts of the wax model assembly. After the gaps are sealed, the shell is made. After the shell is made, the shell at the wax removal hole is opened at the cutting line before the dewaxing process begins. This ensures that the model wax can be discharged from the shell in a timely and efficient manner during the dewaxing process, avoiding the formation of micro-cracks in the shell caused by the expansion of the model wax due to high temperature and high pressure steam. However, traditional wax removal holes have two drawbacks. First, the shell at the wax removal hole is uneven after opening along the cutting line. The adhesion strength of refractory materials such as sand and powder on the end face is inconsistent, which can easily cause secondary inclusions in the shell cavity. Second, before the casting process, after the shell cavity is blown and cleaned, the wax removal hole needs to be repaired to prevent alloy liquid from overflowing and ignition. The traditional repair method is to wrap the end of the wax removal hole with aluminum foil, and then seal it with refractory mud made of silica sol and refractory materials. After a second firing, the alloy liquid is poured. The drawback of this repair method is that after wrapping the mold with aluminum foil and then sealing it with a mixture of refractory mortar, the aluminum foil "ashes" and falls off after the mold shell undergoes a second high-temperature firing, exposing the rough mixture of refractory mortar to the surface of the mold shell cavity. Both of these factors easily lead to secondary inclusions in the mold shell. Setting multiple wax removal holes of this type significantly increases the risk of inclusions in the mold shell cavity. After the casting operation, surface inclusions and internal inclusions are frequently found during non-destructive testing of the casting products, directly leading to the scrapping of the casting products, seriously affecting the product qualification rate, and causing serious waste of resources. Therefore, there is an urgent need to design and develop a universal, simple wax removal hole and matching sealing plug that can effectively improve the quality of ceramic mold shells.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a wax removal structure and a method for preparing the shell for improving the quality of the shell.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] On one hand, the present invention provides a wax removal structure for improving the quality of the product shell. The wax removal structure includes a wax removal hole and a sealing plug adapted to the wax removal hole. One end of the wax removal hole is disposed on the product shell, and the other end is provided with a flange structure on its outer circumference. A first cutting edge is provided between the flange structure and the wax removal hole, and on the outer circumference of the wax removal hole near the flange structure, to facilitate breaking the flange structure. The sealing plug is U-shaped. The maximum outer diameter of the top end of the sealing plug is adapted to the inner diameter of the wax removal hole, and the maximum diameter of the bottom end is greater than the outer diameter of the wax removal hole. A second cutting edge is provided on the side of the bottom end of the sealing plug on the circumference of the bottom end, and near the top end of the sealing plug.

[0009] During assembly, the end face of the wax discharge hole after removing the flange structure abuts against the bottom end and the side near the top of the sealing plug.

[0010] Specifically, the bottom end of the sealing plug has a raised structure facing the wax discharge hole.

[0011] On the other hand, the present invention provides a method for preparing a shell, the specific preparation steps of which are as follows:

[0012] Step 1: First, according to the specific shapes of the wax discharge holes and sealing plugs in the wax discharge structure as described above, make a wax pressing mold, and then press multiple wax molds for the wax discharge holes and sealing plugs respectively;

[0013] Step 2: According to the design requirements of the shell assembly process, attach the wax mold with the wax discharge hole to the designated part of the product wax mold module;

[0014] Step 3: Attach multiple sealing plug wax molds to the pre-made wax rod to form a sealing plug wax mold module;

[0015] Step 4: Apply coating and shell-making operations to the sealing plug wax mold assembly and the product wax mold assembly with the wax discharge hole bonded together, according to the process requirements.

[0016] Step 5: After the coating and shell-making process is completed, the initial product shell and the initial sealing plug shell are formed. Cut open the part of the flange structure of each wax discharge hole that is away from the initial product shell to let the wax out. Then, perform the regular shell module dewaxing operation with the initial sealing plug shell.

[0017] Step 6: After the initial product shell is dewaxed, use a tool to break off and remove the flange structure of the wax discharge hole along the first cutting edge, and finally form the product shell.

[0018] After the initial sealing plug shell is dewaxed, the excess shell is broken off along the second cutting edge using a tool and removed to form the sealing plug;

[0019] Step 7: Firing the processed product shell and sealing plug, blowing and washing the fired product shell, and then assembling the sealing plug with the wax discharge hole of the product shell and sealing it for use in subsequent casting.

[0020] Specifically, in step 1, the wax pressing mold is made of mold steel or forged aluminum.

[0021] Specifically, in step 6, the tool is pliers.

[0022] Specifically, in step 7, the roasting process is as follows: First, when the furnace temperature is between room temperature and 90°C (where the temperature can also be selected from 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C, etc.), the product shell and sealing plug are put into the furnace, and then the temperature is raised to 840-860°C at a rate of 240°C / h (where the temperature can also be selected from 845°C, 850°C, 855°C, etc.) and held for 2.5h. Finally, the temperature is lowered to room temperature with the furnace and then taken out for use.

[0023] Specifically, in step 7, the blowing and washing operations are as follows: first, compressed air treated by a refrigerated dryer is used to blow air through the wax discharge hole of the product shell to clean the inner cavity of the product shell; then, a crane is used to lift the product shell and immerse it in clean water, moving it up and down 5-10 times to clean the cavity of the product shell.

[0024] Specifically, in step 7, after the sealing plug is assembled with the wax discharge hole of the product shell, it is wrapped and sealed with refractory mud made of silica sol and refractory material, with silica sol: refractory material = 0.3: 1, wherein the refractory material components are: 80# sand: 200# powder = 1: 1.

[0025] Furthermore, this invention provides a method for preparing a mold shell, and the application of the resulting product mold shell in ceramic mold shell investment castings is as follows:

[0026] Step 1: Cast and assemble the product shell with the sealing plug according to the process requirements to obtain the casting and gating system;

[0027] Step 2: Clean the product shell around the casting and gating system, remove the gating system, and clean and grind the surface of the casting;

[0028] Step 3: Perform X-ray transmission inspection and fluorescence penetrant inspection on the obtained castings.

[0029] Specifically, the prepared castings have a fluorescence penetration test pass rate of over 97.6% after fluorescence polishing and an X-ray transmission test pass rate of over 96.2%.

[0030] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0031] This invention, through standardized design of the wax discharge hole and its matching sealing plug, ensures a smooth and dense ceramic surface on its working surface. This successfully avoids the problem of secondary inclusions in the mold cavity caused by traditional wax discharge holes and their sealing methods, significantly improving the quality of molds used in investment casting. This invention effectively solves the problems of unevenness on the rear end face of the mold after opening at the traditional wax discharge hole location, inconsistent adhesion strength of the refractory material, and the tendency for secondary inclusions to occur due to the ashing and detachment of aluminum foil and the rough exposure of the mixed refractory mortar in traditional repair methods.

[0032] The preparation method of the present invention is simple and easy to operate, reduces the uncertainty caused by factors such as operational differences during product shell cleaning and sealing operations, and greatly improves the efficiency of product shell production, thereby achieving the purpose of reducing costs and increasing benefits.

[0033] This invention can be applied to all investment casting production fields, has strong versatility, can ensure excellent shell production quality, and provides a reliable and efficient shell production solution for the investment casting industry. It helps to promote industry development and improve product quality, and meets the needs of different fields for high-quality investment castings. Attached Figure Description

[0034] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the manufacturing process of the wax-removing hole shell of the present invention;

[0037] Figure 2 This is a cross-sectional view of the manufacturing process of the wax-removing hole shell of the present invention;

[0038] Figure 3 This is a schematic diagram of the manufacturing process of the sealing plug of the present invention;

[0039] Figure 4 This is a cross-sectional view of the manufacturing process of the sealing plug of the present invention;

[0040] Figure 5 This is a schematic diagram of the assembly process of the wax discharge hole and sealing plug of the present invention;

[0041] Figure 6 This is a three-dimensional schematic diagram of the wax discharge hole and sealing plug after assembly according to the present invention;

[0042] Figure 7 This is a schematic flowchart of the preparation method of the shell of the present invention. Detailed Implementation

[0043] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0044] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0045] This invention provides a wax removal structure for improving the quality of molded shells. The wax removal structure includes a wax removal hole and a sealing plug adapted to the wax removal hole. One end of the wax removal hole is disposed on the product molded shell, and the other end has a flange structure on its outer periphery. Between the flange structure and the wax removal hole, and on the outer periphery of the wax removal hole near the flange structure, there is a first cutting edge (the corresponding first cutting edge on the wax mold of the wax removal hole) to facilitate breaking the flange structure. See [link to relevant documentation]. Figure 1 As shown; the sealing plug is U-shaped, the maximum outer diameter of the top end of the sealing plug matches the inner diameter of the wax discharge hole, and the maximum diameter of the bottom end is larger than the outer diameter of the wax discharge hole. A second cutting edge is provided on the side of the bottom end of the sealing plug circumferentially and close to the top end of the sealing plug; see also Figure 2 As shown;

[0046] During assembly, the end face of the wax discharge hole after removing the flange structure abuts against the bottom end and the side near the top of the sealing plug.

[0047] Specifically, the bottom end of the sealing plug has a raised structure facing the wax discharge hole.

[0048] See Figure 1-7 As shown, the present invention also provides a method for preparing a shell, the specific preparation steps of which are as follows:

[0049] Step 1: First, according to the shape of the wax discharge hole and the sealing plug in the wax discharge structure as described above, make a wax pressing mold, and then press multiple wax molds for the wax discharge hole and the sealing plug respectively; wherein, the included angle of the first cutting edge of the wax discharge hole wax mold is 27°, the length of the first cutting edge is 2mm, the width of the cutting edge is 1mm, and the radius of the cutting edge R is <0.3mm; the included angle of the second cutting edge of the sealing plug wax mold is 50°, the width of the second cutting edge is 4mm, and the radius of the cutting edge R is <0.3mm.

[0050] Step 2: According to the design requirements of the shell assembly process, attach the wax mold with the wax discharge hole to the designated part of the product wax mold module;

[0051] Step 3: Attach multiple sealing plug wax molds to the pre-made wax rod to form a sealing plug wax mold module;

[0052] Step 4: Apply coating and shell-making operations to the sealing plug wax mold assembly and the product wax mold assembly with the wax discharge hole bonded together, according to the process requirements.

[0053] Step 5: After the coating and shell-making process is completed, the initial product wax model shell and the initial sealing plug wax model shell are formed. Cut open the part of the flange structure of each wax discharge hole that is away from the initial product wax model shell to let the wax out. Then, perform the conventional shell module dewaxing operation with the initial sealing plug model shell.

[0054] Step 6: After the initial product shell is dewaxed, use a tool to break off the flange structure of the wax discharge hole along the first cutting edge, and then remove it to finally form the product shell.

[0055] After the initial sealing plug shell is dewaxed, the excess shell is broken off along the second cutting edge using a tool and then removed to form the sealing plug;

[0056] Step 7: Firing the processed product shell and sealing plug, blowing and washing the fired product shell, and then assembling the sealing plug with the wax discharge hole of the product shell and sealing it for use in subsequent casting.

[0057] Specifically, in step 1, the wax pressing mold is made of mold steel or forged aluminum.

[0058] Specifically, in step 6, the tool is pliers.

[0059] Specifically, in step 7, the roasting process is as follows: First, when the furnace temperature is between room temperature and 90°C (where the temperature can also be selected from 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C, etc.), the product shell and sealing plug are put into the furnace, and then the temperature is raised to 840-860°C at a rate of 240°C / h (where the temperature can also be selected from 845°C, 850°C, 855°C, etc.) and held for 2.5h. Finally, the temperature is lowered to room temperature with the furnace and then taken out for use.

[0060] Specifically, in step 7, the blowing and washing operations are as follows: first, compressed air treated by a refrigerated dryer is used to blow air through the wax discharge hole of the product shell to clean the inner cavity of the product shell; then, a crane is used to lift the product shell and immerse it in clean water, moving it up and down 5-10 times to clean the cavity of the product shell.

[0061] Specifically, in step 7, after the sealing plug is assembled with the wax discharge hole of the product shell, it is wrapped and sealed with refractory mud made of silica sol and refractory material, with silica sol: refractory material = 0.3: 1, wherein the refractory material components are: 80# sand: 200# powder = 1: 1.

[0062] This invention also provides a method for preparing a mold shell, and the application of the product mold shell obtained by this method in ceramic mold shell investment castings, as detailed below:

[0063] Step 1: Cast and assemble the product shell with the sealing plug according to the process requirements to obtain the casting and gating system;

[0064] Step 2: Clean the product shell around the casting and gating system, remove the gating system, and clean and grind the surface of the casting;

[0065] Step 3: Perform X-ray transmission inspection and fluorescence penetrant inspection on the obtained castings.

[0066] Specifically, the prepared castings have a fluorescence penetration test pass rate of over 97.6% after fluorescence polishing and an X-ray transmission test pass rate of over 96.2%.

[0067] To verify the effectiveness of the present invention, the following embodiments were used for verification:

[0068] Example

[0069] This embodiment provides a load-bearing casing for a certain type of aircraft engine. The casting has an outline dimension of φ476mm (diameter) × 635mm (height), a minimum wall thickness of 1.5mm, and a complex thin-walled casting structure consisting of multiple layers of flared shapes and multiple hollow support plates connected through it. Technical requirements: The surface of the casting is not allowed to have defects such as inclusions or slag inclusions; the interior of the casting is not allowed to have inclusions or slag inclusions with a diameter greater than 0.5mm; the casting is not allowed to be repaired by welding. The specific steps are as follows:

[0070] Step 1: Design and manufacture wax pressing molds made of mold steel or forged aluminum according to requirements. The molds are multi-cavity. Use special wax pressing equipment to press wax molds for the wax discharge hole and sealing plug separately, and store them for later use. Among them, the included angle of the first cutting edge of the wax discharge hole wax mold is 27°, the length of the first cutting edge is 2mm, the width of the cutting edge is 1mm, and the radius of the cutting edge R is <0.3mm. The included angle of the second cutting edge of the sealing plug wax mold is 50°, the width of the second cutting edge is 4mm, and the radius of the cutting edge R is <0.3mm.

[0071] Step 2: According to the product assembly process design requirements, attach the wax mold with the wax discharge hole to the designated location of the wax mold module of the engine load-bearing casing;

[0072] Step 3: Attach sealing plug wax molds to the pre-made wax rods, multiple molds per group, and put into production with multiple molds;

[0073] Step 4: Apply coating and shell-making operations to the assembled engine load-bearing casing wax mold assembly and sealing plug wax mold assembly according to the process requirements;

[0074] Step 5: After the coating and shell making operation is completed, the initial engine load-bearing casing wax model shell and the initial sealing plug wax model shell are formed. Cut open the part of the flange structure of each wax discharge hole that is away from the initial product wax model shell to let the wax out. Then, perform the conventional shell module dewaxing operation with the initial sealing plug wax model shell.

[0075] Step 6: After dewaxing the engine load-bearing casing wax model shell, the engine load-bearing casing shell is obtained. Using pliers, break off the flange structure of the wax discharge hole shell along the "first cutting edge" as required. (See below) Figure 1 and 2 As shown, a ceramic-patterned wax discharge hole with a smooth and tight end face is formed, consistent with the surface of the engine load-bearing casing cavity, ultimately forming the engine load-bearing casing; that is, after the initial sealing plug wax model shell is dewaxed, the sealing plug shell is obtained. The sealing plug wax model shell is then cut along the specified cutting line as required, see [reference]. Figure 3 and 4 As shown, the excess shell is then broken off along the "second cutting edge" using pliers to form a sealing plug with a smooth and dense ceramic working surface, which is consistent with the ceramic surface of the engine load-bearing casing shell cavity. Multiple units are produced in a group, and multiple modules are put into production and stored for later use.

[0076] Step 7: The processed engine load-bearing casing and sealing plug are fired according to process requirements. First, when the furnace temperature is between room temperature and 90℃ (selectable temperatures also include 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 60℃, 70℃, 80℃, etc.), the engine load-bearing casing and sealing plug are placed into the furnace. Then, the temperature is increased to 840-860℃ at a rate of 240℃ / h (selectable temperatures also include 845℃, 850℃, 855℃, etc.). The furnace is heated to ℃ (etc.) for 2.5 hours, and then cooled to room temperature to complete the calcination. The calcined engine load-bearing casing shell is then subjected to blowing and washing operations according to process requirements. After blowing and washing, the sealing plug is assembled with the wax discharge hole on the engine load-bearing casing shell and the sealing operation is completed. A refractory mortar mixture of silica sol and refractory material is used for encapsulation and sealing, wherein the ratio of silica sol to refractory material is 0.3:1, and the refractory material composition is 80# Shangdian sand to 200# Shangdian powder = 1:1; see [link / reference]. Figure 5 and 6 As shown, the remaining sealing plugs are stored for future use;

[0077] Step 8: Cast the engine load-bearing casing shell with the sealing plug installed according to the casting method required by the process, and obtain the engine load-bearing casing casting;

[0078] Step 9: Clean the engine load-bearing casing casting and the outer mold shell of the gating system, remove the gating system, and clean and grind the surface of the engine load-bearing casing casting;

[0079] Step 10: Perform X-ray transmission inspection and fluorescence penetrant inspection on the obtained engine load-bearing casing casting.

[0080] Following this method, no foreign matter was found to fall into the mold cavity during the subsequent blowing, washing, and shaking processes of the engine load-bearing casing mold shell made with the wax discharge hole and sealing plug prepared by this method; after X-ray transmission inspection and fluorescence penetrant inspection, more than 90.6% of the engine load-bearing casing castings were free of inclusion defects; more than 97.6% of the engine load-bearing casing castings passed the fluorescence penetrant inspection after fluorescence polishing; and more than 96.2% of the engine load-bearing casing castings passed the X-ray transmission inspection, with an overall first-pass yield rate of more than 94.7%.

[0081] The preparation method of the present invention is not limited to the preparation of engine load-bearing casing shells. The preparation method of the present invention can be used to prepare corresponding shells for a certain type of aluminum alloy turbine end volute casting, a certain type of engine intake casing casting, a certain type of engine diffuser housing casting, a certain type of engine compressor casing casting, etc.

[0082] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0083] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A wax removal structure for improving the quality of shell molds, characterized in that, The wax discharge structure includes a wax discharge hole and a sealing plug adapted to the wax discharge hole. One end of the wax discharge hole is set on the product shell, and the other end has a flange structure on its outer circumference. A first cutting edge is provided between the flange structure and the wax discharge hole, and on the outer circumference of the wax discharge hole near the flange structure, to facilitate breaking the flange structure. The sealing plug is Z-shaped. The maximum outer diameter of the top end of the sealing plug is adapted to the inner diameter of the wax discharge hole, and the maximum diameter of the bottom end is greater than the outer diameter of the wax discharge hole. A second cutting edge is provided on the side of the bottom end of the sealing plug, near the top end of the sealing plug. During assembly, the end face of the wax discharge hole after removing the flange structure abuts against the bottom end and the side near the top of the sealing plug.

2. The wax removal structure according to claim 1, characterized in that, The bottom end of the sealing plug has a raised structure facing the wax discharge hole.

3. A method for preparing a shell, characterized in that, The specific preparation steps are as follows: Step 1: First, according to the specific shape of the wax discharge hole and the sealing plug in the wax discharge structure described in claim 1 or 2, make a wax pressing mold, and then press multiple wax molds of the wax discharge hole and the sealing plug respectively; Step 2: According to the design requirements of the shell assembly process, attach the wax mold with the wax discharge hole to the designated part of the product wax mold module; Step 3: Attach multiple sealing plug wax molds to the pre-made wax rod to form a sealing plug wax mold module; Step 4: Apply coating and shell-making operations to the sealing plug wax mold assembly and the product wax mold assembly with the wax discharge hole bonded together, according to the process requirements. Step 5: After the coating and shell-making process is completed, the initial product shell and the initial sealing plug shell are formed. Cut open the part of the flange structure of each wax discharge hole that is away from the initial product shell to let the wax out. Then, dewaxing is performed on the initial sealing plug shell. Step 6: After the initial product shell is dewaxed, use a tool to break off the flange structure of the wax discharge hole along the first cutting edge to finally form the product shell; After the initial sealing plug shell is dewaxed, the excess shell is broken off along the second cutting edge using a tool to form the sealing plug; Step 7: Firing the processed product shell and sealing plug, blowing and washing the fired product shell, and then assembling the sealing plug with the wax discharge hole of the product shell and sealing it for use in subsequent casting.

4. The preparation method according to claim 3, characterized in that, In step 1, the wax pressing mold is made of mold steel or forged aluminum.

5. The preparation method according to claim 3, characterized in that, In step 6, the tool is pliers.

6. The preparation method according to claim 3, characterized in that, In step 7, the roasting process is as follows: First, when the furnace temperature is between room temperature and 90°C, the product shell and sealing plug are put into the furnace, then the temperature is raised to 840-860°C and held for a certain period of time, and finally the furnace is cooled down to room temperature and taken out for use.

7. The preparation method according to claim 3, characterized in that, In step 7, the blowing and washing operations are as follows: First, compressed air treated by a refrigerated dryer is used to blow air through the wax discharge hole of the product shell to clean the inner cavity of the product shell; then, a crane is used to lift the product shell and immerse it in clean water, moving it up and down 5-10 times to clean the cavity of the product shell.

8. The preparation method according to claim 3, characterized in that, In step 7, after the sealing plug is assembled with the wax discharge hole of the product shell, it is wrapped and sealed with refractory mud made of silica sol and refractory material.

9. The application of the product shell prepared by any one of claims 3-8 in ceramic shell investment castings, characterized in that, Specifically as follows: Step 1: Pour and assemble the product shell with sealing plugs according to the process requirements to obtain the casting and gating system; Step 2: Clean the product shell around the casting and gating system, remove the gating system, and clean and grind the surface of the casting; Step 3: Perform X-ray transmission inspection and fluorescence penetrant inspection on the obtained castings.

10. The application according to claim 9, characterized in that, The prepared castings had a fluorescence penetration test pass rate of over 97.6% after fluorescence polishing and an X-ray transmission test pass rate of over 96.2%.

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