A method of making a wax pattern

Abstract

The application discloses a preparation method of a wax mold, which comprises the following steps: designing a wax mold groove in a thick area of the wax mold, so that the wax mold groove is located in a breakable area of a thin-wall core; preparing a metal bump on a wax mold mold, the metal bump being matched with the shape of the wax mold groove, and the first end surface of the metal bump being provided with a first preset distance from the breakable area of the thin-wall core; placing the thin-wall core in the wax mold mold, fixing the relative position of the thin-wall core through a positioning end, and pressing the wax mold mold to form an initial wax mold through wax injection; taking out the metal bump to form a wax mold groove in the initial wax mold; placing the initial wax mold in a wax mold working room environment to cool and form a wax mold body; and checking the integrity of the thin-wall core to screen qualified wax mold bodies. The preparation method of the wax mold provided by the application improves the stability of the size of the wax mold, and avoids the breakage of the structure of the thin-wall core.

Description

Technical Field

[0001] This invention relates to the field of investment casting technology for blades, and more specifically, to a method for preparing a wax model. Background Technology

[0002] As the direct power component of an aircraft, the aero-engine determines its stability and economy, and is a direct reflection of a nation's scientific and technological level and defense capabilities. With the development trend of high-power, low-fuel-consumption aero-engines with high thrust-to-weight ratios, and the continuous increase in turbine inlet temperature, the turbine blades, as key components at the hot end of the aero-engine, are also experiencing increasingly higher operating temperatures. Currently, the turbine inlet temperature of aero-engines exceeds 1500℃. Due to the limitations imposed by the melting point of high-temperature alloys, methods to improve the blade's temperature resistance by increasing the alloy's melting point are nearing their limit. Therefore, optimizing the air-cooling structure of the blades to increase their cooling efficiency has become a trend in blade design and manufacturing. The complex internal cooling channels of the blades require core forming to achieve this.

[0003] In the existing technology, the internal cavity of hollow blades is a slender structure, which requires the use of a core molding. At the same time, the dimensions of the blade structure vary greatly at different locations. In some places, the thickness of the wax material in the wax mold is more than three times that of the core. As a result, after the wax mold body is directly pressed, during the cooling process of the wax mold, the stress caused by the shrinkage of the wax material in the thicker areas will directly lead to the fracture at the stress concentration location caused by the change in the thin-walled core structure.

[0004] Therefore, how to avoid the fracture of thin-walled core structures has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing a wax mold to avoid the breakage of the thin-walled core structure.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a wax model, comprising the following steps:

[0008] Design a wax pattern groove in the thick area of ​​the wax pattern. The wax pattern covers the outer side of the thin-walled core. The thin-walled core includes a breakable area and a positioning end. The wax pattern groove is located in the breakable area of ​​the thin-walled core.

[0009] Prepare a metal bump by preparing a metal bump on a wax mold that matches the shape of the groove of the wax mold, and the first end face of the metal bump is used to have a first preset distance from the easily broken area of ​​the thin-walled core, and the second end face of the metal bump is used to be flush with the outer surface of the wax mold.

[0010] Pressing a wax model involves placing the thin-walled core in the wax model mold, fixing the relative position of the thin-walled core by the positioning end of the thin-walled core, so that the metal protrusion of the wax model mold is located in the easily broken area of ​​the thin-walled core, and forming the first preset distance between the first end face of the metal protrusion and the easily broken area of ​​the thin-walled core. The wax model mold is then pressed and injected with wax using a wax injection device to form an initial wax model.

[0011] After the wax model cools, the metal protrusion is removed from the mold, so that the initial wax model forms the wax model groove at the position of the metal protrusion. The initial wax model is then placed in the wax model working environment to cool and solidify, allowing the wax material to shrink and form the wax model body.

[0012] Inspect the thin-walled core, check the integrity of the thin-walled core on the wax model body, and screen out qualified wax model bodies.

[0013] Optionally, the above preparation method further includes the step of:

[0014] A matching wax block is prepared to match the groove of the wax model. The matching wax block is filled into the groove of the qualified wax model body, and the matching wax block and the wax model body are placed in the wax model working environment to cool and solidify, so as to form the finished wax model.

[0015] Optionally, in the above preparation method, in the step of inspecting the thin-walled core, an X-ray device is used to inspect whether the wax model body breaks during the cooling and shrinkage process.

[0016] Optionally, in the above preparation method, in the step of preparing the metal bump, the first preset distance is not greater than 0.5 mm.

[0017] Optionally, in the above preparation method, the wax mold groove is a stepped groove, the stepped groove includes a first step portion and a second step portion connected to the first step portion, the cross-sectional area of ​​the first step portion is larger than the cross-sectional area of ​​the second step portion, and the cross-sectional area of ​​the first step portion gradually decreases from the cross-sectional area of ​​the second step portion to the cross-sectional area of ​​the second step portion, and the bottom wall of the second step portion has the first preset distance from the thin-walled core.

[0018] Optionally, in the above preparation method, the vertical projected area of ​​the bottom wall of the second step portion is greater than the vertical projected area of ​​the easily broken region of the thin-walled core.

[0019] Optionally, in the above preparation method, in the step of filling the matching wax block, there is a second preset distance between the matching wax block and the sidewall of the wax mold groove, and there is a second preset distance between the matching wax block and the bottom wall of the wax mold groove, so as to facilitate the filling and assembly of the matching wax block.

[0020] Optionally, in the above preparation method, in the step of filling the matching wax block, the matching wax block is filled into the groove of the wax model, and the gap between the matching wax block and the groove of the wax model is filled by molten paraffin wax, and the position filled by the paraffin wax is scraped flat to obtain the finished wax model.

[0021] Optionally, in the above preparation method, the wax mold has a symmetrical structure, and the fragile area of ​​the thin-walled core is symmetrically provided with the wax mold groove.

[0022] Optionally, in the above preparation method, the thin-walled core is made of a high-temperature resistant ceramic material; and / or,

[0023] The draft angle of the wax mold groove (201) along the mold opening direction is 3° to 5°.

[0024] The method for preparing a wax model provided by this invention includes the steps of designing a wax model groove, preparing a metal bump, pressing the wax model, cooling the wax model, and inspecting a thin-walled core. Specifically, in the step of designing the wax model groove, the groove is designed in the thicker area of ​​the wax model, and the groove is located in the easily breakable region of the thin-walled core. In the step of preparing the metal bump, a metal bump matching the shape of the wax model groove is prepared on the wax model mold, and the first end face of the metal bump is positioned at a first predetermined distance from the easily breakable region of the thin-walled core, while the second end face of the metal bump is flush with the outer surface of the wax model. In the step of pressing the wax model, the thin-walled core is placed in the wax model mold, and its relative position is fixed by a positioning end to ensure that the metal bump of the wax model mold is located in the easily breakable region of the thin-walled core. The metal bump has a first preset distance between its first end face and the fragile area of ​​the thin-walled core to prevent the thin-walled core from breaking under equipment pressure during wax injection. The wax mold is pressed and waxed by the wax injection equipment to form an initial wax mold. In the wax mold cooling step, the metal bump is removed so that the initial wax mold forms a wax mold groove at the position of the metal bump. The initial wax mold is then placed in the wax mold working environment to cool and solidify, and the wax shrinks to form the wax mold body. In the thin-walled core inspection step, the integrity of the thin-walled core is inspected on the wax mold body to select qualified wax mold bodies.

[0025] Compared with the prior art, the wax model preparation method provided by the present invention eliminates the need for directly integrally formed thick wax models by designing wax model grooves in the thick area of ​​the wax model and placing the wax model grooves in the easily broken area of ​​the thin-walled core. This reduces the shrinkage stress generated during the cooling and molding of the thick wax model, which can lead to the breakage of the thin-walled core. At the same time, the first end face of the metal protrusion has a first preset distance from the thin-walled core, which can prevent the metal protrusion from causing the thin-walled core to break under equipment pressure during the wax injection process of the wax model mold. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 The preparation method provided in the embodiments of the present invention is as follows: Figure 1 ;

[0028] Figure 2 The preparation method provided in the embodiments of the present invention is as follows: Figure 2 ;

[0029] Figure 3 This is a schematic diagram of the structure of a thin-walled core provided in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the structure of the wax mold groove provided in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of a pressed wax mold provided in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of a filling and matching wax block provided in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of the structure of the matching wax block provided in an embodiment of the present invention.

[0034] Among them, 100 is the thin-walled core, 101 is the easily broken area, and 102 is the positioning end;

[0035] 200 is the wax model, 201 is the wax model groove, 2011 is the first step, 2012 is the second step, and 202 is the matching wax block;

[0036] 300 is a wax mold, and 301 is a metal bump. Detailed Implementation

[0037] The core of this invention is to provide a method for preparing wax molds to avoid breakage of thin-walled core structures.

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] like Figure 1 As shown, this invention discloses a method for preparing a wax model, including step S100 designing a wax model groove, step S101 preparing a metal bump, step S102 pressing the wax model, step S103 cooling the wax model, and step S104 inspecting the thin-walled core. It should be noted that in the prior art, the internal cavity dimensions of hollow blades are slender structures, requiring core molding. Furthermore, the dimensions of the blade itself vary significantly at different locations, with the wax thickness of the wax model exceeding three times the thickness of the core in some areas. This results in stress caused by shrinkage of the wax material at thicker locations during the cooling process after direct pressing of the wax model, directly leading to fracture at stress concentration points caused by changes in the thin-walled core structure. The wax model preparation method disclosed in this invention eliminates the need for directly integrally formed thick wax models by designing wax model grooves 201 in the thick area of ​​the wax model 200 and positioning the wax model grooves 201 in the easily breakable area 101 of the thin-walled core 100. This reduces the risk of breakage of the thin-walled core 100 caused by shrinkage stress generated during cooling and molding of the thick wax model. Simultaneously, a first preset distance is maintained between the first end face of the metal protrusion 301 and the thin-walled core 100, preventing breakage of the thin-walled core 100 under equipment pressure during wax injection and mold closing of the wax model mold 300. The specific steps of the wax model preparation method are as follows:

[0040] S100, designed with grooves for wax molds;

[0041] A wax pattern groove 201 is designed in the thick area of ​​the wax pattern 200. The wax pattern 200 covers the outer side of the thin-walled core 100, and the thin-walled core 100 includes a breakable area 101 and a positioning end 102. The wax pattern groove 201 is located in the breakable area 101 of the thin-walled core 100. Figure 3 and Figure 4 As shown. To ensure easy removal of the wax model 200 after pressing, the draft angle of the wax model groove 201 along the mold opening direction is 3° to 5°, that is, the inclination angle of the side wall of the wax model groove 201 is 3° to 5°. Specifically, as... Figure 5 and Figure 6As shown, the wax model 200 has a thickness of 3mm in the thickest area, and the wax model groove 201 is a stepped groove. The stepped groove includes a first step portion 2011 and a second step portion 2012 connected to the first step portion 2011. The cross-sectional area of ​​the first step portion 2011 is larger than that of the second step portion 2012, and the cross-sectional area gradually decreases from the first step portion 2011 to the second step portion 2012. Simultaneously, the vertical projected area of ​​the bottom wall of the second step portion 2012 is larger than the vertical projected area of ​​the fragile area 101 of the thin-walled core 100, so that the wax model groove 201 completely covers the fragile area 101 caused by stress concentration in the thin-walled core 100. Furthermore, since the wax model 200 has a symmetrical structure, wax model grooves 201 can be symmetrically arranged on both sides of the fragile area 101 of the thin-walled core 100, thereby preventing the thin-walled core 100 from breaking due to shrinkage stress generated during cooling and shrinkage of the wax model 200. It should be noted that the mold opening direction is the opening direction of the wax mold, that is, it is consistent with the vertical central axis of the wax mold groove 201. The vertical central axis is the central axis of the wax mold groove 201 in the vertical direction.

[0042] In this embodiment, the thin-walled core 100 is made of high-temperature resistant ceramic material. The length of the second step portion 2012 is 15 mm, the maximum width of the second step portion 2012 is 5 mm, and the depth of the second step portion 2012 is 2.5 mm. Furthermore, the bottom wall of the first step portion 2011 is 1 mm, meaning the maximum width of the second step portion 2012 extends outward by 1 mm to facilitate filling and assembling the matching wax block 202, and the depth of the first step portion 2011 is 1 mm. Simultaneously, to ensure convenient demolding after pressing the wax mold 200, the draft angle of the first step portion 2011 and the second step portion 2012 along the mold opening direction is 3°.

[0043] S101, fabrication of metal bumps;

[0044] like Figure 5 As shown, a metal bump 301 matching the shape of the wax mold groove 201 is prepared on the wax mold 300, and the first end face of the metal bump 301 is used to have a first preset distance from the fragile area 101 of the thin-walled core 100, and the second end face of the metal bump 301 is used to be flush with the outer surface of the wax mold 200. Specifically, as shown... Figure 7As shown, the metal bump 301 has a first insertion end and a first snap-fit ​​end, and the metal bump 301 and the wax mold 300 are integrally structured. The first end face of the first insertion end of the metal bump 301 is designed to maintain a first preset distance from the fragile area 101 of the thin-walled core 100, preventing the metal bump 301 from contacting and damaging the thin-walled core 100 during the closing of the wax mold 300 and the pressing process. Furthermore, the first insertion end of the metal bump 301 forms a second step 2012 in the wax mold cooling step S103, and the first snap-fit ​​end of the metal bump 301 forms a first step 2011 in the wax mold cooling step S103.

[0045] S102, pressed wax mold;

[0046] A thin-walled core 100 is placed in a wax mold 300. The positioning end 102 of the thin-walled core 100 fixes its relative position, so that the metal protrusion 301 of the wax mold 300 is located in the breakable region 101 of the thin-walled core 100. A first preset distance is formed between the first end face of the metal protrusion 301 and the breakable region 101 of the thin-walled core 100. Wax is injected into the wax mold 300 using a wax injection device to form an initial wax model. In this embodiment, the first preset distance is no greater than 0.5 mm to prevent the metal protrusion 301 from breaking under the pressure of the device during wax injection. Specifically, as shown... Figure 5 As shown, the wax mold includes an upper mold and a lower mold, which form the upper and lower sides of the wax mold 200, respectively. Before mold closing, the dimensions of the thin-walled core 100 are preliminarily checked using a coordinate measuring machine or a blue light device to ensure that the surface deviation of the thin-walled core 100 does not exceed 0.5mm, thereby selecting a qualified thin-walled core 100 to be placed in the wax mold 300. During mold closing, the metal protrusion 301 is pre-positioned at the breakable area 101 of the thin-walled core 100, and the upper mold and lower mold are fixed in relative position through the positioning end 102 of the thin-walled core 100, thereby completing the mold closing. At this time, wax is pressed and injected into the wax mold 300 using a wax injection device to form the initial wax mold.

[0047] S103, Wax mold cooling;

[0048] The metal bump 301 is removed from the mold, allowing the initial wax model to form a wax model groove 201 at the location of the metal bump 301. The initial wax model is then placed in a wax model working environment to cool and solidify, allowing the wax to shrink and form the main body of the wax model. Specifically, after the initial wax model has cooled to a preliminary stage, the wax model mold 300 is opened along the mold opening direction. At this time, the metal bump 301 is simultaneously removed, allowing the initial wax model to form a wax model groove 201 at the location of the metal bump 301. The initial wax model is then placed in a wax model working environment for more than 2 hours to cool to room temperature, allowing the wax to shrink and form the main body of the wax model. Because a wax pattern groove 201 is formed in the thick area of ​​the initial wax pattern, and the wax pattern groove 201 is located in the easily breakable area 101 of the thin-walled core 100, the problem of directly integrally molding a thick wax pattern is eliminated. This reduces the shrinkage stress generated during the cooling and molding process of the wax material in the wax pattern working environment, thus avoiding the breakage of the thin-walled core 100 caused by the shrinkage stress generated during the cooling and molding of the thick wax pattern. It should be noted that the wax pattern working environment is at room temperature, i.e., natural cooling.

[0049] S104, Inspect thin-walled cores;

[0050] The integrity of the thin-walled core 100 within the wax model body is inspected to select qualified wax model bodies. Specifically, since the thin-walled core 100 is enclosed by the wax model 200, its breakage cannot be directly observed visually. Therefore, X-ray equipment is used to inspect whether the thin-walled core 100 located inside the wax model body remains intact and has not broken. If the thin-walled core 100 is broken and fails, the wax model body is a defective product; if the thin-walled core 100 is intact, the wax model body is a qualified product, thus selecting qualified wax model bodies.

[0051] The method for preparing a wax model disclosed in this invention includes step S100 designing a wax model groove, step S101 preparing a metal bump, step S102 pressing the wax model, step S103 cooling the wax model, and step S104 inspecting the thin-walled core. In step S100, the wax mold groove is designed in the thick area of ​​the wax mold 200, and the wax mold groove 201 is located in the easily broken area 101 of the thin-walled core 100. In step S101, the metal bump is prepared on the wax mold 300, and a metal bump 301 matching the shape of the wax mold groove 201 is prepared, such that the first end face of the metal bump 301 is at a first preset distance from the easily broken area 101 of the thin-walled core 100, and the second end face of the metal bump 301 is flush with the outer surface of the wax mold 200. In step S102, the wax mold is pressed, the thin-walled core 100 is placed in the wax mold 300, and the relative position of the thin-walled core 100 is fixed by the positioning end 102 of the thin-walled core 100 to ensure that the metal bump 301 of the wax mold 300 is located in the thin-walled core 101. The metal protrusion 301 has a first preset distance from the first end face of the metal protrusion 301 to the thin-walled core 100 to prevent the thin-walled core 100 from breaking under equipment pressure during wax injection. The wax mold 300 is pressed and waxed by the wax injection equipment to form an initial wax mold. In the wax mold cooling step S103, the metal protrusion 301 is removed from the mold so that the initial wax mold forms a wax mold groove 201 at the position of the metal protrusion 301. The initial wax mold is placed in the wax mold working environment to cool and form the wax shrinkage to form the wax mold body. In the thin-walled core inspection step S104, the integrity of the thin-walled core 100 is inspected to ensure that the thin-walled core 100 has not broken due to the shrinkage of the initial wax mold, thereby screening out qualified wax mold bodies.

[0052] Compared with the prior art, the wax model preparation method disclosed in this embodiment of the invention eliminates the need for directly integrally formed thick wax models by designing wax model grooves 201 in the thick area of ​​the wax model 200 and placing the wax model grooves 201 in the easily breakable area 101 of the thin-walled core 100. This reduces the shrinkage stress generated during the cooling and molding of the thick wax model, which could lead to the breakage of the thin-walled core 100. At the same time, the first end face of the metal protrusion 301 and the thin-walled core 100 have a first preset distance, which can prevent the metal protrusion 301 from breaking under equipment pressure during the wax injection process of the wax model mold 300.

[0053] Furthermore, such as Figure 2 As shown, the method for preparing a wax model also includes the following steps:

[0054] S105, fill with matching wax block;

[0055] like Figure 6and Figure 7 As shown, a matching wax block 202 is prepared to match the groove 201 of the wax model. The matching wax block 202 is filled into the groove 201 of the qualified wax model body, and the matching wax block 202 and the wax model body are placed in a wax model working environment to cool and solidify, thereby forming a finished wax model. Specifically, there is a second preset distance between the matching wax block 202 and the side wall of the groove 201, and there is a second preset distance between the matching wax block 202 and the bottom wall of the groove 201, so as to facilitate the filling and assembly of the matching wax block 202. The wax model body filled with the matching wax block 202 is placed in a wax model working environment to cool, thereby forming a finished wax model. The matching wax block 202 has a second insertion end and a second snap-fit ​​end, and there is a second preset distance between the second insertion end of the matching wax block 202 and the side wall and bottom wall of the second step portion 2012, while there is a third preset distance between the second snap-fit ​​end of the matching wax block 202 and the side wall of the first step portion 2011. In this embodiment, the second preset distance is 0.1 mm and the third preset distance is 0.2 mm. After the matching wax block 202 is filled into the wax mold groove 201, the gap between the matching wax block 202 and the wax mold groove 201 is filled with molten paraffin wax. The surface of the paraffin wax filling position is scraped and trimmed, and then cooled in the wax mold working environment to obtain the finished wax mold.

[0056] The terms "first" and "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units may include steps or units not listed, but rather steps or units not listed.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use 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. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a wax model, characterized in that, Including the following steps: Design a wax mold groove, and design a wax mold groove (201) in the thick area of ​​the wax mold (200). The wax mold (200) covers the outside of the thin-walled core (100). The thin-walled core (100) includes a breakable area (101) and a positioning end (102). The wax mold groove (201) is located in the breakable area (101) of the thin-walled core (100). Prepare a metal bump by preparing a metal bump (301) on a wax mold (300) that matches the shape of the groove (201) of the wax mold. The first end face of the metal bump (301) is used to have a first preset distance from the easily broken area (101) of the thin-walled core (100), and the second end face of the metal bump (301) is used to be flush with the outer surface of the wax mold (200). Press the wax model, place the thin-walled core (100) in the wax model mold (300), fix the relative position of the thin-walled core (100) by the positioning end (102) of the thin-walled core (100), so that the metal protrusion (301) of the wax model mold (300) is located in the breakable area (101) of the thin-walled core (100), and form the first preset distance between the first end face of the metal protrusion (301) and the breakable area (101) of the thin-walled core (100), and press the wax model mold (300) with wax by the wax injection device to form an initial wax model; After the wax model cools, the metal protrusion (301) is removed from the mold so that the initial wax model forms the wax model groove (201) at the position of the metal protrusion (301). The initial wax model is then placed in the wax model working environment to cool and solidify, and the wax shrinks to form the wax model body. Inspect the thin-walled core, check the integrity of the thin-walled core (100) on the wax model body, and screen out qualified wax model bodies; Fill with matching wax blocks, prepare matching wax blocks (202) that match the groove (201) of the wax model, fill the matching wax blocks (202) into the groove (201) of the qualified wax model body, and place the matching wax blocks (202) and the wax model body in the wax model working environment to cool and solidify, so as to form the finished wax model; The wax mold groove (201) is a stepped groove, which includes a first stepped portion (2011) and a second stepped portion (2012) connected to the first stepped portion (2011). The cross-sectional area of ​​the first stepped portion (2011) is larger than the cross-sectional area of ​​the second stepped portion (2012), and the cross-sectional area of ​​the first stepped portion (2011) gradually decreases from the cross-sectional area of ​​the second stepped portion (2012). The bottom wall of the second stepped portion (2012) has the first preset distance between it and the thin-walled core (100).

2. The preparation method according to claim 1, characterized in that, In the step of inspecting the thin-walled core, X-ray equipment is used to check whether the wax model body breaks during the cooling and shrinkage process.

3. The preparation method according to claim 1, characterized in that, In the step of preparing the metal bump, the first preset distance is no greater than 0.5 mm.

4. The preparation method according to claim 1, characterized in that, The vertical projected area of ​​the bottom wall of the second step (2012) is greater than the vertical projected area of ​​the fragile area (101) of the thin-walled core (100).

5. The preparation method according to claim 1, characterized in that, In the step of filling the matching wax block, there is a second preset distance between the matching wax block (202) and the side wall of the wax mold groove (201), and there is a second preset distance between the matching wax block (202) and the bottom wall of the wax mold groove (201), so as to fill and assemble the matching wax block (202).

6. The preparation method according to claim 5, characterized in that, In the step of filling the matching wax block, the matching wax block (202) is filled into the groove (201) of the wax model, and the gap between the matching wax block (202) and the groove (201) of the wax model is filled by molten paraffin wax, and the position filled by the paraffin wax is scraped flat to obtain the finished wax model.

7. The preparation method according to claim 1, characterized in that, The wax mold (200) has a symmetrical structure, and the fragile area (101) of the thin-walled core (100) is symmetrically provided with the wax mold groove (201).

8. The preparation method according to any one of claims 1 to 7, characterized in that, The thin-walled core (100) is made of high-temperature resistant ceramic material; and / or, The draft angle of the wax mold groove (201) along the mold opening direction is 3° to 5°.

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