Dewaxing structure for improving quality of shell and preparation method of shell

Abstract

The invention belongs to the technical field of precision investment casting, and particularly relates to a dewaxing structure for improving the quality of a shell and a preparation method of the shell. According to the invention, the dewaxing hole and the matched sealing plug are subjected to standardized design, so that the working surface of the dewaxing hole is a smooth and compact ceramic surface, the problem of secondary inclusion of a shell cavity caused by a traditional dewaxing hole and a sealing mode thereof is successfully avoided, and the quality of the shell for precision investment casting is powerfully improved. According to the method, the problems that the end face is uneven after a mold shell at the traditional dewaxing hole part is opened, the adhesion strength of a refractory material is different, aluminum foil paper in a traditional repairing mode is ashed and falls off, mixed refractory mortar is rough and exposed, and secondary inclusion is easily caused are effectively solved. The preparation method has the advantages that the operation is simple and easy, the uncertainty caused by factors such as operation difference in the product shell cleaning and sealing operation process is reduced, and the product shell manufacturing efficiency is greatly improved, so that the purposes of reducing the cost and increasing the benefit are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of investment casting, and in particular relates to a wax removal structure for improving the quality of a mold shell and a method for preparing the mold shell. Background Art

[0002] With the in-depth development of my country's aviation and aerospace industries, various complex silica sol shell investment castings have been widely used in the manufacturing of aviation and aerospace engines. Since these components often serve in harsh working conditions such as high temperature, high pressure, and high corrosion, they have strict requirements on performance indicators in terms of internal quality and surface quality, and are not allowed to repair any kind of defects. Product acceptance is carried out with a near-zero defect standard.

[0003] One of the core points of using investment casting to achieve qualified production of such components is the qualified production of silica sol mold shell; high-quality silica sol mold shell cannot have microcracks, because the presence of microcracks in the mold shell will directly lead to peeling of the surface layer on the inner surface of the shell, which will then place various tiny particles in the shell cavity. Since such components have complex structures and are mostly thin-walled components, it is difficult for tiny particles to be discharged from the shell cavity, resulting in surface or internal slag inclusion defects in the casting after pouring, causing product failure and seriously reducing the product qualification rate. To address this type of problem, on the one hand, multiple wax drainage holes are set up to reduce the expansion of the mold shell caused by the high-temperature and high-pressure steam during dewaxing, which causes the model wax to expand and cannot be discharged out of the mold shell in time, resulting in micro cracks in the mold shell; on the other hand, multiple wax drainage holes can provide multiple channels for subsequent cleaning of foreign matter residues in the mold shell cavity, that is, the wax drainage holes also have the function of cleaning and removing impurities in the subsequent mold shell cavity, which is conducive to the full implementation of the cleaning work of the mold shell and cavity. Starting from both preventing mold shell expansion and facilitating the cleaning of the mold shell and cavity, the probability of defects in castings can be greatly reduced and the qualified rate of castings can be improved.

[0004] The traditional wax draining holes are simple cylindrical wax blocks. They are pasted at various parts of the wax mold module, and after the gaps are closed, the shell-making operation is carried out. After the shell-making is completed, along the cutting line, the shell at the wax draining hole part is opened before the dewaxing work starts, ensuring that the model wax can be discharged from the shell in a timely and efficient manner when the module is dewaxed, and avoiding the generation of micro-cracks in the shell caused by the expansion of the model wax due to high-temperature and high-pressure steam in the module. However, the traditional wax draining holes have two disadvantages. Firstly, after the shell at the wax draining hole part is opened along the cutting line, the end face is uneven, and the adhesion strength of refractory materials such as sand grains and powder materials on the end face is different, which is likely to cause secondary inclusions in the shell cavity. On the other hand, before the pouring operation, after the shell cavity is blown and cleaned, the holes of the wax draining holes need to be repaired to avoid alloy liquid overflow and running fire. The traditional repair method is to wrap the end of the shell wax draining hole with aluminum foil paper, and then wrap and seal it with refractory mud made of silica sol and refractory materials. After secondary calcination, the alloy liquid pouring operation is carried out. The disadvantage of this repair scheme is that after wrapping with aluminum foil paper and then using the mixed refractory mud for wrapping and sealing, after the shell undergoes secondary high-temperature calcination, the aluminum foil paper "ashes" and falls off, and the rough mixed refractory mud is exposed to the surface of the shell cavity. Both are likely to cause secondary inclusions in the shell. Setting such wax draining holes at multiple positions will greatly increase the risk of inclusions in the shell cavity. After the pouring operation, surface inclusions, internal inclusions and other defect problems are often found in the non-destructive inspection of the castings, directly resulting in the scrapping of the castings, seriously affecting the product qualification rate and causing serious waste of resources. Therefore, at present, there is an urgent need to design and develop a general, simple and effective wax draining hole and supporting sealing plug that can improve the quality of the ceramic shell.

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

[0006] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a wax draining structure for improving the quality of the shell and a preparation method of the shell.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] On the one hand, the present invention provides a wax draining structure for improving the quality of the shell. The wax draining structure includes a wax draining hole and a sealing plug adapted to the wax draining hole. One end of the wax draining hole is arranged on the product shell, and a flanging structure is arranged on the outer circumference of the other end. A first cutting edge for easily breaking the flanging structure is arranged between the flanging structure and the wax draining hole and on the outer circumference of the wax draining hole close to the flanging structure. The sealing plug is in a U-shape. The maximum outer diameter of the top end of the sealing plug is adapted to the inner diameter of the wax draining hole, and the maximum diameter of the bottom end is larger than the outer diameter of the wax draining hole. A second cutting edge is arranged on the circumferential direction of the bottom end of the sealing plug and on one side close to the top end of the sealing plug.

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

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

[0011] In another aspect, the present invention provides a method for preparing a mold shell, and the specific preparation steps are as follows:

[0012] Step 1: First, according to the specific shapes of the wax discharge holes and the sealing plugs in the wax discharge structure as described above, a wax pressing mold is made, and then a plurality of wax discharge hole wax molds and sealing plug wax molds are pressed respectively;

[0013] Step 2: According to the requirements of the shell assembly process design, the wax pattern of the wax hole is bonded to the designated position of the product wax pattern module;

[0014] Step 3, bonding a plurality of sealing plug wax molds on the prefabricated wax stick to form a sealing plug wax mold module;

[0015] Step 4, respectively coating and shelling the sealing plug wax mold module and the product wax mold module bonded with the wax drain hole wax mold according to the process requirements;

[0016] Step 5: After the coating and shell making operation is completed, the initial product shell and the initial sealing plug shell are formed, and the flange structure of each wax discharge hole is cut away from the initial product shell to leak the wax, and then the initial sealing plug shell is subjected to conventional shell module dewaxing operation;

[0017] Step 6: After the initial product shell is dewaxed, a tool is used to break off the flange structure of the wax discharge hole along the first cutting edge and then remove it, thereby finally forming a product shell;

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

[0019] Step 7: calculate the processed product shell and the sealing plug, and perform shell blowing and shell washing operations on the calcified product shell. After the operation, assemble the sealing plug and the wax discharge hole of the product shell accordingly, and complete the sealing operation for subsequent casting.

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

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

[0022] Specifically, in step 7, the roasting process is as follows: first, when the furnace temperature is between room temperature and 90°C (wherein, the optional temperatures also include 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C, etc.), put the product shell and the sealing plug into the furnace, and then heat it to 840-860°C (wherein, the optional temperatures also include 845°C, 850°C, 855°C, etc.) at a rate of 240°C / h and keep it warm for 2.5 hours, and finally cool it to room temperature with the furnace and take it out of the furnace for use.

[0023] Specifically, in step 7, the shell blowing and shell washing operations are as follows: first, compressed air treated by a refrigerated dryer is used to blow and clean the inner cavity of the product shell through the wax discharge hole of the product shell; then the product shell is hoisted by a crane and immersed in clean water, and moved 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 correspondingly with the wax discharge hole of the product shell, refractory mud mixed with silica sol and refractory material is used for wrapping and sealing, silica sol: refractory material = 0.3:1, wherein the refractory material components: 80# Shangdian sand: 200# Shangdian powder = 1:1.

[0025] In another aspect, the present invention provides a method for preparing a mold shell and an application of the mold shell obtained by the method in a ceramic mold shell investment casting, as follows:

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

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

[0028] Step 3: Perform X-ray transillumination and fluorescent penetrant inspection on the obtained casting.

[0029] Specifically, the qualified rate of the prepared castings after fluorescent polishing and fluorescent penetrant inspection is above 97.6%, and the qualified rate of the prepared castings after X-ray transillumination inspection is above 96.2%.

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

[0031] The present invention standardizes the design of the wax discharge hole and the matching sealing plug, so that the working surface is a smooth and tight ceramic surface, successfully avoiding the problem of secondary inclusions in the shell cavity caused by the traditional wax discharge hole and its sealing method, and effectively improving the quality of the shell for investment casting. The present invention effectively solves the problem of uneven rear end surface of the shell after opening at the traditional wax discharge hole, uneven adhesion strength of refractory materials, and the problem of aluminum foil ash falling off and mixed refractory mud being rough and exposed in the traditional repair method, which is easy to cause secondary inclusions.

[0032] The preparation method of the present invention is simple and easy to operate, reduces the uncertainty caused by factors such as operation 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] The present invention can be applied to all investment casting production fields, has strong versatility, can ensure excellent quality of mold shell production, provides a reliable and efficient mold shell production solution for the investment casting industry, helps promote the development of the industry and improve product quality, and meets the needs of different fields for high-quality investment castings. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0036] Figure 1 It is a schematic diagram of the process of making the wax removal hole shell of the present invention;

[0037] Figure 2 A cross-sectional view of the wax removal hole shell manufacturing process of the present invention;

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

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

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

[0041] Figure 6 It is a three-dimensional schematic diagram of the wax drain hole and the sealing plug after being assembled according to the present invention;

[0042] Figure 7 It is a schematic flow chart of the method for preparing the mold shell of the present invention. DETAILED DESCRIPTION

[0043] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention as detailed in the appended claims.

[0044] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0045] The present invention provides a wax discharge structure for improving the quality of a mold shell, the wax discharge structure comprising a wax discharge hole and a sealing plug matched with the wax discharge hole, one end of the wax discharge hole is arranged on the product mold shell, and a flange structure is arranged on the outer circumference of the other end, and a first cutting edge (corresponding to the first cutting edge on the wax discharge hole wax mold) for facilitating breaking off the flange structure is arranged between the flange structure and the wax discharge hole and on the outer circumference of the wax discharge hole close to the flange structure, see Figure 1 As shown; the sealing plug is in the shape of a Chinese character "X", the maximum outer diameter of the top of the sealing plug is adapted to the inner diameter of the wax discharge hole, the maximum diameter of the bottom is larger than the outer diameter of the wax discharge hole, and a second cutting edge is provided on one side of the bottom circumference of the sealing plug and close to the top of the sealing plug; see Figure 2 As shown;

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

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

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

[0049] Step 1, firstly, according to the shapes of the wax discharge holes and the sealing plugs in the wax discharge structure as described above, a wax pressing mold is made, and then a plurality of wax discharge hole wax molds and sealing plug wax molds are pressed respectively; wherein, the angle of the first edge of the wax discharge hole wax mold is 27°, the edge length of the first edge is 2mm, the edge width is 1mm, and the radius R of the blade tip is less than 0.3mm; the angle of the second edge of the sealing plug wax mold is 50°, the edge width of the second edge is 4mm, and the radius R of the blade tip is less than 0.3mm;

[0050] Step 2: According to the requirements of the shell assembly process design, the wax pattern of the wax hole is bonded to the designated position of the product wax pattern module;

[0051] Step 3, bonding a plurality of sealing plug wax molds on the prefabricated wax stick to form a sealing plug wax mold module;

[0052] Step 4, respectively coating and shelling the sealing plug wax mold module and the product wax mold module bonded with the wax drain hole wax mold according to the process requirements;

[0053] Step 5: After the coating and shell making operation is completed, the initial product wax model shell and the initial sealing plug wax model shell are formed, and the flange structure of each wax discharge hole is cut away from the initial product wax model shell to leak the wax, and then the conventional shell mold module dewaxing operation is carried out with the initial sealing plug shell;

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

[0056] Step 7: calculate the processed product shell and the sealing plug, and perform shell blowing and shell washing operations on the calcified product shell. After the operation, assemble the sealing plug and the wax discharge hole of the product shell accordingly, and complete the sealing operation for subsequent casting.

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

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

[0059] Specifically, in step 7, the roasting process is as follows: first, when the furnace temperature is between room temperature and 90°C (wherein, the optional temperatures also include 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C, etc.), put the product shell and the sealing plug into the furnace, and then heat it to 840-860°C (wherein, the optional temperatures also include 845°C, 850°C, 855°C, etc.) at a rate of 240°C / h and keep it warm for 2.5 hours, and finally cool it to room temperature with the furnace and take it out of the furnace for use.

[0060] Specifically, in step 7, the shell blowing and shell washing operations are as follows: first, compressed air treated by a refrigerated dryer is used to blow and clean the inner cavity of the product shell through the wax discharge hole of the product shell; then the product shell is hoisted by a crane and immersed in clean water, and moved 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 correspondingly with the wax discharge hole of the product shell, it is wrapped and sealed with refractory mud mixed with silica sol and refractory material, silica sol: refractory material = 0.3:1, wherein the refractory material components: 80# Shangdian sand: 200# Shangdian powder = 1:1.

[0062] The present invention also provides a method for preparing a mold shell and an application of the mold shell obtained by the method in ceramic mold shell investment casting, which is as follows:

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

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

[0065] Step 3: Perform X-ray transillumination and fluorescent penetrant inspection on the obtained casting.

[0066] Specifically, the qualified rate of the prepared castings after fluorescent polishing and fluorescent penetrant inspection is above 97.6%, and the qualified rate of the prepared castings after X-ray transillumination inspection is above 96.2%.

[0067] To verify the effect of the present invention, the following examples are used for verification:

[0068] Example

[0069] This embodiment provides a certain type of engine bearing casing for aviation, the casting outline size is φ476mm (diameter) × 635mm (height), the thinnest wall thickness is 1.5mm, the structure is a complex thin-walled casting with multiple layers of trumpet-shaped + multiple hollow support plates connected through, the technical requirements are: no inclusions, slag inclusions and other defects are allowed on the casting surface, no inclusions, slag inclusions and other defects with a diameter greater than 0.5mm and above are allowed inside the casting, and no repair welding is allowed for the casting, and the specific steps are as follows:

[0070] Step 1, design and manufacture a wax pressing mold of die steel or forged aluminum according to requirements, and manufacture multiple cavities in one mold. Use special wax pressing equipment to press the wax mold for the wax hole and the wax mold for the sealing plug respectively, and store them for standby; wherein, the angle of the first edge of the wax mold for the wax hole is 27°, the length of the first edge is 2mm, the width of the edge is 1mm, and the radius of the blade tip is R<0.3mm; the angle of the second edge of the wax mold for the sealing plug is 50°, the width of the second edge is 4mm, and the radius of the blade tip is R<0.3mm;

[0071] Step 2: According to the product combination process design requirements, glue the wax pattern of the wax hole to the designated position of the engine bearing casing wax pattern module;

[0072] Step 3, bonding the sealing plug wax mold on the prefabricated wax stick, one group of multiple, multi-module group production;

[0073] Step 4, respectively coating and shelling the assembled engine bearing casing wax mold module and sealing plug wax mold module according to the process requirements;

[0074] Step 5: After the coating and shell making operation is completed, the initial engine bearing casing wax model shell and the initial sealing plug wax model shell are formed, and the flange structure of each wax discharge hole is cut away from the initial product wax model shell to leak the wax, and then the conventional shell mold group dewaxing operation is carried out with the initial sealing plug wax model shell;

[0075] Step 6: After the dewaxing of the wax model shell of the engine bearing casing is completed, the engine bearing casing shell is obtained. According to the requirements, the flange structure of the wax discharge hole shell is broken off along the "first cutting edge" using pliers, see Figure 1 and 2 As shown, a smooth and tight ceramic surface wax discharge hole is formed on the end face, which is consistent with the surface of the engine bearing casing shell cavity, and finally the engine bearing casing shell is formed; that is, after the initial sealing plug wax model shell is dewaxed, a sealing plug shell is obtained, and the sealing plug wax model shell is cut along the specified cutting line as required, see Figure 3 and 4 As shown, pliers are then used to break off the excess shell along the "second cutting edge" to form a sealing plug with a smooth and tight ceramic working surface, which is consistent with the ceramic surface of the engine load-bearing casing shell cavity. Multiple groups and multiple modules are put into production and stored for standby use.

[0076] Step 7: The processed engine bearing casing shell and the sealing plug are roasted according to the process requirements. First, when the furnace temperature is between room temperature and 90°C (wherein the optional temperature also includes 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C, etc.), the engine bearing casing shell and the sealing plug are put into the furnace, and then the temperature is raised to 840-860°C (wherein the optional temperature also includes 845°C, 850°C, 855°C, etc.) at a rate of 240°C / h. ℃, etc.) for 2.5h, and finally cool down to room temperature with the furnace to complete the roasting. The roasted engine bearing casing shell is subjected to shell blowing and shell washing operations according to the process requirements. After the shell blowing and shell washing operations are completed, the sealing plug is assembled with the wax discharge hole on the engine bearing casing shell according to the requirements and the sealing operation is completed. The refractory mud mixed with silica sol and refractory material is used for wrapping and sealing, wherein the silica sol: refractory material = 0.3:1, and the refractory material components: 80# Shangdian sand: 200# Shangdian powder = 1:1; see Figure 5 and 6 As shown, the remaining sealing plugs are stored for future use;

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

[0078] Step 9, clean the engine bearing casing casting and the outer mold shell of the pouring system, remove the pouring system, and clean and polish the surface of the engine bearing casing casting;

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

[0080] According to this method, in the engine bearing case mold shell made of the wax drainage hole and the sealing plug thereof prepared by the preparation method, no foreign matter was found to fall out of the mold shell cavity during the subsequent blowing, washing and shaking of the mold shell; after the engine bearing case castings were subjected to X-ray transillumination inspection and fluorescent penetration inspection, more than 90.6% of the engine bearing case castings were free of inclusion defects; more than 97.6% of the engine bearing case castings passed the fluorescent penetration inspection after fluorescent polishing inspection; more than 96.2% of the engine bearing case castings passed the X-ray transillumination inspection, and the comprehensive first-time inspection pass rate was more than 94.7%.

[0081] The preparation method of the present invention is not limited to the preparation of engine load-bearing casing mold shells. The preparation method of the present invention can be used to prepare corresponding mold 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 only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0083] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may 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, characterized in that: The wax discharging structure includes a wax discharging hole and a sealing plug adapted to the wax discharging hole. One end of the wax discharging hole is arranged on the product shell mold, and a flanging structure is arranged on the outer circumference of the other end. A first cutting edge for easily breaking the flanging structure is arranged between the flanging structure and the wax discharging hole and on the outer circumference of the wax discharging hole close to the flanging structure; the sealing plug is in a U-shape. The maximum outer diameter of the top end of the sealing plug is adapted to the inner diameter of the wax discharging hole, and the maximum diameter of the bottom end is larger than the outer diameter of the wax discharging hole. A second cutting edge is arranged on the outer circumference of the bottom end of the sealing plug and on one side close to the top end of the sealing plug; During assembly, the end face of the wax discharging hole after removing the flanging structure abuts against the bottom end of the sealing plug and on one side close to the top end.

2. The wax removal structure according to claim 1, characterized in that: The bottom end of the sealing plug is a翘起 structure facing the wax discharging hole.

3. A method for preparing a mold shell, characterized in that: The specific preparation steps are as follows: Step 1. First, according to the specific shapes of the wax discharging hole and the sealing plug in the wax discharging structure described in Claim 1 or 2, a wax pressing mold is made, and then a plurality of wax discharging hole wax molds and sealing plug wax molds are respectively pressed; Step 2. According to the design requirements of the shell mold combination process, the wax discharging hole wax mold is bonded to the specified part of the product wax mold module; Step 3. A plurality of sealing plug wax molds are bonded to a prefabricated wax rod to form a sealing plug wax mold module; Step 4. The sealing plug wax mold module and the product wax mold module bonded with the wax discharging hole wax mold are respectively subjected to the shell making operation of coating and hanging according to the process requirements; Step 5. After the shell making operation of coating and hanging is completed, an initial product shell mold and an initial sealing plug shell mold are formed. The part of the flanging structure of each wax discharging hole far from the initial product shell mold is cut open to leak the wax, and then the dewaxing operation is carried out with the initial sealing plug shell mold; Step 6. After the dewaxing of the initial product shell mold is completed, the flanging structure of the wax discharging hole is broken along the first cutting edge by using a tool to finally form a product shell mold; After the dewaxing of the initial sealing plug shell mold is completed, the redundant shell mold is broken along the second cutting edge by using a tool to form a sealing plug; Step 7. The processed product shell mold and the sealing plug are baked. After the baking of the product shell mold is completed, the shell mold is blown and washed. After the operation is completed, the sealing plug is correspondingly assembled with the wax discharging hole of the product shell mold, and the sealing operation is completed for subsequent casting of castings.

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

5. The preparation method according to claim 3, characterized in that: In Step 6, the tool is a pair of pliers.

6. The preparation method according to claim 3, characterized in that: In Step 7, the specific baking process is as follows: First, when the furnace temperature is from room temperature to 90 °C, the product shell mold and the sealing plug are put into the furnace, then the temperature is raised to 840 - 860 °C and kept for a certain time, and finally the temperature is lowered to room temperature with the furnace and taken out for standby.

7. The preparation method according to claim 3, characterized in that: In Step 7, the specific operations of blowing and washing the shell mold are as follows: First, compressed air treated by a refrigerated dryer is used to blow and clean the inner cavity of the product shell mold through the wax discharging hole of the product shell mold; then the product shell mold is hoisted by a crane and immersed in clean water and reciprocated up and down 5 - 10 times to wash the cavity of the product shell mold.

8. The preparation method according to claim 3, characterized in that: In Step 7, after the sealing plug is correspondingly assembled with the wax discharging hole of the product shell mold, a refractory mud mixed with silica sol and refractory material is used for wrapping and sealing.

9. Application of the product shell obtained by the preparation method according to any one of claims 3 to 8 in ceramic shell investment casting, characterized in that: Specifically as follows: Step 1: Cast and assemble the product shell with the sealing plug according to the process requirements to obtain the casting and the pouring system; Step 2: clean the product shell around the casting and the gating system, remove the gating system, and clean and polish the casting surface; Step 3: Perform X-ray transillumination and fluorescent penetrant inspection on the obtained casting.

10. The use according to claim 9, characterized in that: The qualified rate of the prepared castings after fluorescent polishing and fluorescent penetration inspection is above 97.6%, and the qualified rate of the prepared castings after X-ray transillumination inspection is above 96.2%.

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