Method for preparing shells containing multi-angle irregular cavities

Abstract

This invention provides a method for preparing a shell mold containing multi-angle irregularly shaped cavities. The method includes: assembling a core with multiple segmented wax molds, such that the core is placed within the multi-angle irregularly shaped cavity formed by the combined wax molds; at least a portion of the core's tubular body has the same inner diameter as the corresponding segmented wax mold cavity for precise fit; the remaining portion of the core's tubular body is suspended within the multi-angle irregularly shaped cavity, resulting in a casting wax film; preparing a surface shell and a back shell sequentially on the surface of the casting wax film; and then employing segmented continuous dewaxing and firing to obtain the shell mold. This invention utilizes the multi-angled tubular bodies of the core to form a multi-dimensional fit with the segmented wax molds, ensuring both precise fit between the segmented wax molds and the core, and leveraging the core's dimensional accuracy to guarantee the dimensional accuracy of the casting's internal cavity later.

Description

Technical Field

[0001] This invention relates to the field of casting mold preparation technology, specifically to a method for preparing a mold containing multi-angle irregularly shaped cavities. Background Technology

[0002] Titanium alloy precision castings are prepared using investment casting, also known as lost-wax casting. Investment casting typically involves creating a pattern from a fusible material, coating the pattern with several layers of refractory material to form a shell, melting the pattern and removing it from the shell, then firing it at high temperature to obtain the final casting. Molten metal is then poured into the shell to obtain the casting. The process generally includes wax pressing, shell preparation, dewaxing, pouring molten metal, and post-treatment. Therefore, the quality of the titanium alloy shell has a significant impact on the forming of titanium alloy castings.

[0003] For precision titanium alloy castings, due to the requirement for unified structure and function, the internal structure is complex, often containing blind cavities. This necessitates the use of ceramic cores to form these complex internal cavities. After casting, the cores are removed to create the internal cavity structure. Therefore, during the wax pressing process, a core is placed in the wax pressing mold before wax is poured in, forming a wax model with the core. For castings with complex internal cavities, a method of preparing segmented wax models in different areas and then assembling them into a single, integral wax model is typically used. Since the integral wax model is composed of multiple parts, misalignment can easily occur during assembly when fitting the segmented wax models and multi-angled cavity cores due to dimensional accuracy issues. This can prevent precise assembly of the segmented wax models with the cores, thus affecting the dimensional accuracy of the casting. For wax models with internal cores, the cores are susceptible to displacement and breakage due to the impact of molten wax during the wax pressing process. Meanwhile, since the shell needs to be made by high-temperature baking, the high-temperature baking process has a certain impact on the core. For shells with an internal core, after dewaxing, the core is only connected to the shell by the fixed end, and the rest is a suspended structure. During high-temperature baking, it is prone to cracking or displacement due to thermal expansion and contraction. The baking process needs to be controlled to stabilize the quality of the shell and core. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the main objective of the present invention is to provide a method for preparing a shell containing multi-angle irregularly shaped cavities. In this method, multiple tubes distributed at multiple angles of the core are used to form a multi-dimensional fit with the segmented wax mold, which not only ensures the precise fit between the segmented wax mold and the core, but also ensures the dimensional accuracy of the inner cavity of the casting by utilizing the dimensional accuracy of the core.

[0005] To achieve the above objectives, the present invention provides a method for preparing a shell containing multi-angle irregularly shaped cavities, comprising the following steps: preparing a core according to the cavity structure of a casting, the core comprising multiple tubes distributed at multiple angles; designing multiple segmented wax molds according to the cavity structure of the casting, and assembling the core with the multiple segmented wax molds, such that the core is placed within the multi-angle irregularly shaped cavity formed by the multiple segmented wax molds, thereby obtaining a casting wax film; wherein, at least a portion of the tubes of the core has the same inner diameter as the corresponding multi-angle irregularly shaped cavity for precise fit, and at least a portion of the remaining portion of the tubes is suspended in the multi-angle irregularly shaped cavity; preparing a surface shell and a back shell sequentially on the surface of the casting wax film, followed by segmented continuous dewaxing and firing to obtain the shell containing multi-angle irregularly shaped cavities.

[0006] In some embodiments of the present invention, the preparation of the surface shell includes: applying a surface slurry to the surface of the casting wax model, then removing excess surface slurry; then performing surface sanding, and after drying, forming the surface shell.

[0007] In some embodiments of the present invention, the preparation of the back layer shell includes: coating the surface of the surface layer shell with a back layer slurry, removing excess back layer slurry; then performing back layer sandblasting, and after drying, forming a first back layer shell; repeating the steps of coating the back layer slurry and back layer sandblasting in the preparation of the back layer shell multiple times to form a multi-layer back layer shell.

[0008] In some embodiments of the present invention, the segmented continuous dewaxing and roasting includes: dewaxing, heating to a first roasting temperature, holding at the temperature, and allowing the wax liquid to flow out from the dewaxing port; roasting, sequentially heating to a second, third, and fourth roasting temperature, and holding at the second, third, and fourth roasting temperatures respectively, and then cooling and removing from the furnace.

[0009] In some embodiments of the present invention, the first calcination temperature is 100°C to 200°C, and the holding time at the first calcination temperature is 3h to 6h.

[0010] In some embodiments of the present invention, the wax flows out from the wax outlet in the middle or side of the bottom region of the mold shell.

[0011] In some embodiments of the present invention, the second calcination temperature is 400℃~500℃, and the holding time at the second calcination temperature is ≥3h, preferably 3h~6h.

[0012] In some embodiments of the present invention, the third calcination temperature is 650°C to 750°C, and the holding time at the third calcination temperature is ≥3h, preferably 3h to 6h.

[0013] In some embodiments of the present invention, the fourth calcination temperature is 950℃~1200℃, and the holding time at the fourth calcination temperature is ≥3h, preferably 3h~8h.

[0014] In some embodiments of the present invention, the furnace is cooled to room temperature before being removed from the furnace, or cooled to below 300°C before being removed from the furnace.

[0015] In some embodiments of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is ≤10mm, the distance between the suspended portion of the tube body and the cavity wall of the multi-angle irregular tube cavity at the corresponding position is ≤1mm; when the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is >10mm, the distance between the suspended portion of the tube body and the cavity wall of the multi-angle irregular tube cavity at the corresponding position is ≤2mm.

[0016] In some embodiments of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended portion of the tube body is ≤3mm, the distance between the suspended portion of the tube body and the cavity wall of the multi-angle irregular tube cavity at the corresponding position is ≤0.5mm.

[0017] In some embodiments of the present invention, designing multiple segmented wax models according to the structure of the casting cavity includes: dividing the multiple tubes of the core into X tubes, Y tubes, and Z tubes according to the extension direction of the tubes; using the plane formed by the center lines of the X tubes and the Y tubes as a first dividing plane, and the plane formed by the center lines of the X tubes and the part of the Z tubes connected to the X tubes as a second dividing plane, dividing the multiple segmented wax models at corresponding positions of the casting wax model, and respectively serving as the bottom wax model, the rear wax model, and the front wax model.

[0018] In some embodiments of the present invention, the X-tube, the Y-tube, and the Z-tube represent the three-dimensional coordinate axes X-axis, Y-axis, and Z-axis where the tube is located, and there is at least one X-tube, Y-tube, and Z-tube.

[0019] In some embodiments of the present invention, a first pipe groove is provided on the bottom wax mold, a second pipe groove is provided on the rear wax mold, and a third pipe groove is provided on the front wax mold; the first pipe groove, the second pipe groove, and the third pipe groove together form the multi-angle irregular cavity.

[0020] In some embodiments of the present invention, the assembly of the core and the plurality of segmented wax molds includes: placing the X-tube, Y-tube and part of the Z-tube of the core in the first channel groove of the bottom wax mold for positioning in the X, Y and Z directions; assembling the front wax mold and the rear wax mold onto the bottom wax mold respectively, with the front wax mold and the rear wax mold aligned, such that part of the second channel groove and part of the third channel groove surround to form a cavity for sleeved part of the Z-tube, and such that the first channel groove and part of the third channel groove and part of the second channel groove surround to form a cavity for sleeved X-tube, Y-tube and part of the Z-tube.

[0021] In some embodiments of the present invention, the Z tube body further includes a Z1 tube body connected to the Y tube body, and the rear wax mold is further provided with a through-tube cavity for fitting the Z1 tube body.

[0022] In some embodiments of the present invention, a portion of the Z1 tube body has the same inner diameter as the corresponding sleeve cavity for precise fit, while the remaining portion of the Z1 tube body is suspended in the sleeve cavity.

[0023] In some embodiments of the invention, at least a portion of the core tube passes through the inner cavity of the shell and protrudes outside the shell.

[0024] In some embodiments of the present invention, the shell preparation method further includes: after dewaxing and baking, performing quality testing on the core; and cleaning the interior of the shell by blowing air.

[0025] In some embodiments of the present invention, an endoscope is used to inspect the interior of the shell.

[0026] Advantages of this invention:

[0027] In this invention, the multi-dimensional fit between the multi-angled tubes of the core and the segmented wax mold ensures precise fit between the segmented wax mold and the core, and the dimensional accuracy of the core can be used to ensure the dimensional accuracy of the inner cavity of the casting later.

[0028] The method of preparing the core by suspending at least a portion of the tube body in a multi-angle irregular cavity in the present invention can avoid the problem that the core cannot be assembled with the multi-angle cavity in a certain dimension due to the multiple tube bodies distributed at multiple angles.

[0029] This invention utilizes the plane formed by the centerlines of the X, Y, and Z tubes of the core as the dividing surface of the wax model, separating the wax model containing multi-angled cavities into a front wax model, a rear wax model, and a bottom wax model. Therefore, the splicing of the front, rear, and bottom wax models inevitably involves the positioning of the wax models in the X, Y, and Z three-dimensional directions, which helps to ensure accurate positioning of the wax model containing multi-angled cores in all three dimensions during the splicing process. This, in turn, ensures accurate positioning of the complex internal cavities of the shell.

[0030] In this invention, the dewaxing temperature is higher than that of conventional electric dewaxing, allowing the wax to be quickly removed from the mold shell and reducing the impact of the wax removal process on the core's positional displacement. Simultaneously, increasing the first firing temperature preheats the mold shell, which helps to reduce the second firing holding time.

[0031] In this invention, the dewaxing and firing processes of the mold shell are carried out continuously. By continuously and progressively increasing the firing temperature, the wax inside the mold shell is removed and the shell is ceramicized through high-temperature firing. Furthermore, because the mold shell is heated gradually, core deformation or displacement caused by thermal expansion and contraction during the heating process is reduced. Simultaneously, continuous dewaxing and firing improves heating efficiency and effectively reduces the heating and holding time at each stage. Attached Figure Description

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings:

[0033] Figure 1 This is a schematic diagram of the core structure in an embodiment provided by the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of the bottom wax mold in the embodiments provided by the present invention;

[0035] Figure 3 This is a schematic diagram of the structure after the bottom wax mold and the core are assembled in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the structure of the front wax model in the embodiment provided by the present invention;

[0037] Figure 5 This is a schematic diagram of the structure of the core, bottom wax model and front wax model after assembly in the embodiment provided by the present invention;

[0038] Figure 6 Schematic diagram of the post-wax mold structure in the embodiments provided by the present invention Figure 1 ;

[0039] Figure 7 Schematic diagram of the post-wax mold structure in the embodiments provided by the present invention Figure 2 ;

[0040] Figure 8 This is a schematic diagram of the wax model structure of the casting provided in the embodiments of the present invention.

[0041] In the picture:

[0042] 1. Core; 11. X tube body; 12. Y tube body; 13. Z1 tube body; 14. Z2 tube body; 15. Z3 tube body; 16. Z4 tube body;

[0043] 2. Bottom wax mold; 21. First pipe groove; 22. First positioning protrusion; 23. Second positioning protrusion;

[0044] 3. Rear wax mold; 31. Second pipe groove; 32. Through-sleeve cavity;

[0045] 4. Front wax model; 41. Third pipe groove;

[0046] 5. Splice the top surface. Detailed Implementation

[0047] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0048] Reference Figures 1-8 As shown, the method for preparing the shell containing multi-angle irregular cavities in this embodiment of the invention is carried out according to the following steps.

[0049] (1) Preparation of core 1.

[0050] In an embodiment of the present invention, core 1 is prepared according to the casting cavity structure.

[0051] In an embodiment of the present invention, the core 1 includes multiple tubes distributed at multiple angles. The multiple tubes are distributed in different orientations in the X, Y, and Z three dimensions, which can be understood as the core 1 having a multi-angled pipe-like structure.

[0052] Figure 1 The diagram shows a specific structural schematic of a core 1.

[0053] According to the extension direction of the tube body, the multiple tube bodies that make up the core 1 are divided into X tube body 11, Y tube body 12 and Z tube body, wherein: Z tube body includes Z1 tube body 13, Z2 tube body 14, Z3 tube body 15 and Z4 tube body 16.

[0054] In an embodiment of the present invention, Z1 tube 13 is connected to Y tube 12, Z2 tube 14 is connected to X tube 11, and Z1 tube 13 and Z2 tube 14 are arranged in opposite directions.

[0055] In an embodiment of the present invention, tube Z3 15 is connected at the junction of tube X 11 and tube Y 12, and tube Z4 16 is connected at the junction of tube X 11 and tube Y 12.

[0056] In some embodiments of the present invention, the X tube 11 includes the X1 tube and the X2 tube; the Y tube 12 includes the Y1 tube and the Y2 tube.

[0057] (2) Design multiple segmented wax molds according to the structure of the casting cavity.

[0058] The wax model of the casting containing multi-angle irregular cavities in this invention is obtained by assembling multiple segmented wax models and core 1.

[0059] In an embodiment of the present invention, each segmented wax mold has a pipe groove formed thereon, and multiple segmented wax molds together form a multi-angle irregular cavity. The core 1 is placed in the multi-angle irregular cavity, thereby obtaining a casting wax film containing a multi-angle irregular cavity.

[0060] In some embodiments of the present invention, designing multiple segmented wax molds according to the structure of the casting cavity includes the following steps: dividing the multiple tubes of the core 1 into X tubes, Y tubes, and Z tubes according to the extension direction of the tubes; using the plane formed by the center lines of the X tubes and Y tubes as the first dividing surface to divide the casting wax mold at the corresponding position to obtain the bottom wax mold 2; and using the plane formed by the center lines of the X tubes and the part of the Z tubes connected to the X tubes as the second dividing surface to divide the remaining wax mold at the corresponding position to obtain the rear wax mold 3 and the front wax mold 4.

[0061] Therefore, the splicing of the front wax model 4, the rear wax model 3 and the bottom wax model 2 inevitably involves the positioning of the wax models in the three-dimensional directions of X, Y and Z, which helps to ensure that the wax models containing multi-angle cores are accurately positioned in all three dimensions during the splicing process.

[0062] The bottom wax model 2 has a first pipe groove 21, the rear wax model 3 has a second pipe groove 31, and the front wax model 4 has a third pipe groove 41. The core 1 is assembled with the bottom wax model 2, the rear wax model 3, and the front wax model 4, and the core 1 is placed in the multi-angle irregular cavity formed by the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41.

[0063] (3) Assemble the core 1 with multiple segmented wax molds to prepare the casting wax film.

[0064] In an embodiment of the present invention, at least a portion of the tube body of the core 1 has the same inner diameter as the multi-angle irregular cavity at the corresponding position for precise fit, and the remaining portion of the tube body is suspended in the multi-angle irregular cavity.

[0065] The present invention employs a method in which at least a portion of the core 1 is suspended in a multi-angle irregular cavity, which avoids the problem that the core 1 cannot be assembled with the multi-angle cavity in a certain dimension due to the presence of multiple tubes distributed at multiple angles.

[0066] In this invention, the multi-dimensional fit between the tube body of the core 1 and the segmented wax mold is formed by the multi-angle distribution of the tube body. This ensures that the segmented wax mold and the core 1 fit precisely, and the dimensional accuracy of the core 1 can be used to ensure the dimensional accuracy of the inner cavity of the casting later.

[0067] In some embodiments of the present invention, the inner diameter at the port of at least a portion of the core 1 is the same as the inner diameter at the port of the multi-angle shaped cavity for precise fit, and the remaining portion of at least a portion of the core is suspended in the multi-angle cavity.

[0068] The present invention employs a method in which the port of the multi-angle irregular cavity is precisely matched with the port of at least part of the tube body of the core 1, while the remaining part of the tube body is suspended in the multi-angle irregular cavity. This method avoids the problem that the core 1 cannot be assembled with the multi-angle cavity in a certain dimension due to the multiple tube bodies distributed at multiple angles.

[0069] In an embodiment of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended part of the pipe body is ≤10mm, the distance between the suspended part of the pipe body and the cavity wall of the multi-angle irregular pipe cavity at the corresponding position is ≤1mm. It can also be understood that the distance between the suspended part of the pipe body and the groove walls of the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41 at the corresponding position is ≤1mm.

[0070] In an embodiment of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended part of the pipe body is >10mm, the distance between the suspended part of the pipe body and the cavity wall of the multi-angle irregular pipe cavity at the corresponding position is ≤2mm. It can also be understood that the distance between the suspended part of the pipe body and the groove walls of the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41 at the corresponding position is ≤2mm.

[0071] In some embodiments of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended part of the tube body is ≤3mm, the distance between the suspended part of the tube body and the cavity wall of the multi-angle irregular tube cavity at the corresponding position is ≤0.5mm. It can also be understood that the distance between the suspended part of the tube body and the groove walls of the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41 at the corresponding position is ≤0.5mm.

[0072] In an embodiment of the present invention, the spacing design between the suspended part of the tube body and the cavity wall of the multi-angle special-shaped tube cavity at the corresponding position can meet the assembly requirements of the core 1 and also meet the requirements of shrinkage and deformation of the wax mold.

[0073] It is worth mentioning that in the present invention, the spacing between the suspended part of the tube body and the cavity wall of the multi-angle special-shaped tube cavity can also be designed according to the proportional relationship between the spacing d between the suspended part of the tube body and the cavity wall of the multi-angle special-shaped tube cavity and the wall thickness x of the wax mold corresponding to the suspended part of the tube body.

[0074] Among them, the proportional relationship formula is: d = kx;

[0075] In the formula, k is the proportionality coefficient, d is the spacing between the suspended part of the tube body and the cavity wall of the multi-angle special-shaped tube cavity at the corresponding position, and x is the wall thickness of the wax mold.

[0076] In some embodiments of the present invention, when 1 mm ≤ x ≤ 8 mm, 0.4 ≤ k ≤ 0.5.

[0077] In some embodiments of the present invention, when 8 mm < x ≤ 20 mm, 0.1 ≤ k ≤ 0.15.

[0078] In some embodiments of the present invention, the length of the tube body with the same inner diameter at the port of the tube body ≥ 8 mm to ensure high-precision fitting.

[0079] As an implementation manner of the present invention, the combined assembly of the core 1 and multiple segmented wax molds includes the following steps:

[0080] (3-1) Assemble the core 1 onto the bottom wax mold 2 to obtain a combined structure of the core 1 and the bottom wax mold 2.

[0081] Figure 3 A schematic structural diagram of a bottom wax mold 2 is shown, Figure 4 A schematic diagram of the combined structure of assembling the core 1 onto the bottom wax mold 2 is shown.

[0082] In an embodiment of the present invention, place the core 1 corresponding to the first pipe groove 21 of the bottom wax mold 2, place part of the tube body in the first pipe groove 21, and achieve positioning in the X, Y, and Z directions to prevent the core 1 from sliding in the first pipe groove 21.

[0083] In some embodiments of the present invention, place the X tube body 11, Y tube body 12 and part of the Z tube body of the core 1 corresponding to the first pipe groove 21 of the bottom wax mold 2 for positioning in the X, Y, and Z directions.

[0084] In some embodiments of the present invention, the X tube 11, Y tube 12, and Z2 tube 14 of the core 1 are placed correspondingly in the first channel groove 21 of the bottom wax mold 2. The X tube 11 and Y tube 12 respectively mate with a portion of the first channel groove 21 (which can be called the first core groove) to be positioned in the X and Y directions; the Z2 tube 14 mates with a portion of the first channel groove 21 (which can be called the first positioning groove) to be positioned in the Z direction. At this time, the core 1 is positioned in the X, Y, and Z directions by the X tube 11, Y tube 12, and Z2 tube 14, preventing the core 1 from sliding in the first channel groove 21.

[0085] It is worth mentioning that the inner diameters at the ports of the X tube 11 and Y tube 12 of the core 1 are the same as the inner diameters at the ports of the first pipe groove 21 at the corresponding positions, which is a precision fit.

[0086] The inner diameter of the remaining parts of the X tube 11 and Y tube 12 of the core 1 is smaller than the inner diameter of the first pipe groove 21 at the corresponding position. After the core 1 is assembled into the first pipe groove 21, the X tube 11 and Y tube 12 are fixed only through the port of the first pipe groove 21, and the remaining parts of the X tube 11 and Y tube 12 are suspended in the first pipe groove 21.

[0087] In some embodiments of the present invention, the inner diameter of the Z2 tube 14 is the same as the inner diameter of the first pipe groove 21 at the corresponding position for a precise fit, ensuring accurate positioning in the Z direction.

[0088] In some embodiments of the present invention, when the wall thickness of the casting wax model corresponding to the suspended portion of the X-tube 11 and Y-tube 12 is ≤10mm, the distance between the suspended portion of the X-tube 11 and Y-tube 12 and the cavity wall of the multi-angle irregular cavity at the corresponding position is ≤1mm. It can also be understood that the distance between the suspended portion of the X-tube 11 and Y-tube 12 and the groove wall of the first pipe groove 21 at the corresponding position is ≤1mm.

[0089] In some embodiments of the present invention, when the wall thickness of the casting wax model corresponding to the suspended portion of the X-tube 11 and Y-tube 12 is >10mm, the distance between the suspended portion of the X-tube 11 and Y-tube 12 and the cavity wall of the multi-angle irregular cavity at the corresponding position is ≤2mm. It can also be understood that the distance between the suspended portion of the X-tube 11 and Y-tube 12 and the groove wall of the first pipe groove 21 at the corresponding position is ≤2mm.

[0090] In some embodiments of the present invention, when the wall thickness of the casting wax model corresponding to the suspended portion of the X-tube 11 and Y-tube 12 is ≤3mm, the distance between the suspended portion of the X-tube 11 and Y-tube 12 and the cavity wall of the multi-angle irregular cavity at the corresponding position is ≤0.5mm. It can also be understood that the distance between the suspended portion of the X-tube 11 and Y-tube 12 and the groove wall of the first pipe groove 21 at the corresponding position is ≤0.5mm.

[0091] (3-2) Assemble the front wax mold 4 onto the bottom wax mold 2 to obtain the combined structure of the core 1, the bottom wax mold 2 and the front wax mold 4.

[0092] Figure 5 A schematic diagram of a front wax mold 4 is shown. The structure of the core 1, bottom wax mold 2, and front wax mold 4 after assembly is as follows. Figure 6 As shown.

[0093] In an embodiment of the present invention, the third pipe groove 41 of the front wax mold 4 is provided in a corresponding part of the pipe body, and the front wax mold 4 is assembled onto the bottom wax mold 2.

[0094] In some embodiments of the present invention, a portion of the third pipe groove 41 corresponds to a portion of the first pipe groove 21 and surrounds it for connecting the X pipe body 11 and the Y pipe body 12.

[0095] In some embodiments of the present invention, a portion of the third pipe groove 41 is provided corresponding to the Z3 pipe body 15 and the Z4 pipe body 16.

[0096] After the front wax mold 4 is assembled with the X tube 11, Y tube 12 and Z2 tube 14 of the core 1, it is assembled onto the bottom wax mold 2. Therefore, the front wax mold 4 and the bottom wax mold 2 are positioned in the X and Y directions, and the front wax mold 4 cannot move in the X and Y directions, thus ensuring accurate assembly in the X and Y directions.

[0097] It is worth mentioning that the inner diameter of the port of the third pipe groove 41 of the front wax mold 4 is the same as the inner diameter of the port of the corresponding fitting pipe body, which is a precision fit.

[0098] The inner diameter of the remaining part of the third pipe groove 41 is larger than the inner diameter of the corresponding pipe body. After the current wax model 4 is assembled onto the bottom wax model 2, the X pipe body 11, Y pipe body 12 and part of the Z pipe body, such as Z3 pipe body 15 and Z4 pipe body 16, are fixed only through the port of the third pipe groove 41. The remaining parts of the X pipe body 11, Y pipe body 12 and part of the Z pipe body are suspended in the third pipe groove 41.

[0099] In some embodiments of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 is ≤10mm, the distance between the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 and the groove wall of the third pipe groove 41 at the corresponding position is ≤1mm.

[0100] In some embodiments of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 is >10mm, the distance between the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 and the groove wall of the third pipe groove 41 at the corresponding position is ≤2mm.

[0101] In some embodiments of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 is ≤3mm, the distance between the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 and the groove wall of the third pipe groove 41 at the corresponding position is ≤0.5mm.

[0102] In an embodiment of the present invention, a second positioning protrusion 23 is also provided on the bottom wax mold 2. The second positioning protrusion 23 is used for positioning and assembly with the front wax mold 4, so that the front wax mold 4 and the bottom wax mold 2 form a positioning assembly.

[0103] (3-3) Assemble the rear wax mold 3 onto the bottom wax mold 2 to obtain the combined structure of core 1, bottom wax mold 2, front wax mold 4 and rear wax mold 3.

[0104] Figure 7 A schematic diagram of the structure of a post-wax mold 3 is shown. Figure 1 , Figure 8 A schematic diagram of the structure of a post-wax mold 3 is shown. Figure 2 The overall structure after assembling the core 1, bottom wax mold 2, front wax mold 4, and rear wax mold 3 is as follows: Figure 8 As shown.

[0105] In an embodiment of the present invention, the second pipe groove 31 of the rear wax mold 3 is placed corresponding to a portion of the tube body of the core 1, and the rear wax mold 3 is assembled onto the bottom wax mold 2. The front wax mold 4 and the rear wax mold 3 are aligned, such that a portion of the second pipe groove 31 of the rear wax mold 3 and a portion of the third pipe groove 41 of the front wax mold 4 enclose a cavity for a sleeved portion of the Z tube body, such as the cavity of the Z3 tube body 15 and the Z4 tube body 16. At the same time, the first pipe groove 21 of the bottom wax mold 2, a portion of the third pipe groove 41 and a portion of the second pipe groove 31 enclose a cavity for a sleeved X tube body 11, Y tube body 12 and a portion of the Z tube body, such as the Z2 tube body 14.

[0106] After the rear wax mold 3 is assembled with the X tube 11, Y tube 12 and Z4 tube 16 of the core 1, it is assembled onto the bottom wax mold 2 and the front wax mold 4. Therefore, the rear wax mold 3, the front wax mold 4 and the bottom wax mold 2 are positioned in the X and Y directions, and the rear wax mold 3 cannot move in the X and Y directions, thus ensuring accurate assembly in the X and Y directions.

[0107] It is worth mentioning that the inner diameter of the port of the second pipe groove 31 of the rear wax mold 3 is the same as the inner diameter of the port of the corresponding fitting pipe body, which is a precision fit.

[0108] The inner diameter of the remaining part of the second pipe groove 31 is larger than the inner diameter of the corresponding pipe body. After the rear wax model 3 is assembled onto the bottom wax model 2, the X pipe body 11, Y pipe body 12 and part of the Z pipe body, such as Z3 pipe body 15 and Z4 pipe body 16, are fixed only through the port of the second pipe groove 31. The remaining parts of the X pipe body 11, Y pipe body 12 and part of the Z pipe body are suspended in the second pipe groove 31.

[0109] In some embodiments of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 is ≤10mm, the distance between the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 and the groove wall of the second pipe groove 31 at the corresponding position is ≤1mm.

[0110] In some embodiments of the present invention, when the wall thickness of the casting wax model corresponding to the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 is >10mm, the distance between the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 and the groove wall of the second pipe groove 31 at the corresponding position is ≤2mm.

[0111] In some embodiments of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 is ≤3mm, the distance between the suspended portion of the X-tube 11, Y-tube 12, Z3-tube 15, and Z4-tube 16 and the groove wall of the second pipe groove 31 at the corresponding position is ≤0.5mm.

[0112] In some embodiments of the present invention, the inner diameter of the Z2 tube 14 is the same as the inner diameter of the second pipe groove 31 at the corresponding position for a precise fit.

[0113] It can be understood that the inner diameter of Z2 tube body 14 is the same as the inner diameter of the multi-angle irregular cavity at the corresponding position for precise fit.

[0114] In an embodiment of the present invention, the rear wax model 3 is further provided with at least one through-tube cavity 32, which is sleeved on the corresponding Z-tube body. Through the through-tube cavity 32, the front wax model 4 and the rear wax model 3 are fixed as a whole, restricting the movement of the front wax model 4 and the rear wax model 3 in the Z direction, ensuring the integrity of the sequentially spliced ​​front wax model 4 and the rear wax model 3, and forming the positioning of the front wax model 4 and the rear wax model 3 in the Z direction.

[0115] As one embodiment of the present invention, the rear wax mold 3 is provided with a through-tube cavity 32 for sleeved onto the Z1 tube body 13.

[0116] It is worth mentioning that a portion of the Z1 tube body 13 has the same inner diameter as the corresponding sleeve cavity 32 for precise fit, while the remaining portion of the Z1 tube body 13 is suspended in the sleeve cavity 32.

[0117] In an embodiment of the present invention, at least a portion of the core 1 tube passes through a multi-angle irregularly shaped cavity and protrudes outside the casting wax model, that is, the core 1 tube has a portion protruding from the casting wax model.

[0118] (3-4) Melt at least part of the joint between the bottom wax model 2, the rear wax model 3, and the front wax model 4 and fuse them together.

[0119] In an embodiment of the present invention, after the overall assembly is completed, a cover is set outside the position where the core 1 and the segmented wax molds are spliced ​​and the casting wax mold is exposed. The cover is made of an elastic material that can tightly fix at least two segmented wax molds and the core 1.

[0120] Then, at point 5 on the top surface of the splicing, the wax model in the local area of ​​the splicing seam is melted, and the splicing seam is fused together, splicing the segmented wax models into a whole.

[0121] Finally, remove the envelope.

[0122] In embodiments of the present invention, a soldering iron can be selected as the tool for melting the seam.

[0123] (4) The surface shell and the back shell are prepared sequentially on the wax film surface of the casting.

[0124] The preparation of the surface shell includes: applying a surface slurry to the surface of the wax model of the casting, and then removing the excess surface slurry; then applying surface sand, and after drying, forming the surface shell.

[0125] The preparation of the back layer shell includes: coating the surface of the surface layer shell with back layer slurry and removing excess back layer slurry; then performing back layer sanding and drying to form the first back layer shell; repeating the coating and sanding steps in the preparation of the back layer shell multiple times to form a multi-layer back layer shell.

[0126] It is worth mentioning that during the application of the top and back layers of slurry, the tubes that pass through the multi-angle irregularly shaped cavities and protrude outside the casting wax mold are protected, ensuring that this part of the tubes of the core 1 is always exposed outside the shell.

[0127] It should be noted that the surface of the wax model can be cleaned before applying the topcoat slurry to prepare the topcoat shell to remove surface stains.

[0128] (5) A shell containing multi-angle irregular cavities was obtained by adopting segmented continuous dewaxing and baking.

[0129] (5-1) Dewaxing: Heat to the first firing temperature, keep warm, and let the wax flow out from the dewaxing port.

[0130] In embodiments of the present invention, the first firing temperature is 100℃ to 200℃, for example, it can be one of 100℃, 110℃, 117℃, 120℃, 150℃, 180℃, 200℃ or any value satisfying the above range; the holding time is 3h to 6h, for example, it can be one of 3h, 4h, 5h, 6h or any value satisfying the above range. The dewaxing temperature is higher than the conventional electric dewaxing temperature, which allows the wax liquid to be quickly removed from the inside of the mold shell, reducing the impact of the wax liquid removal process on the core position displacement. At the same time, increasing the first firing temperature has a preheating effect on the mold shell, which helps to reduce the second firing holding time.

[0131] In an embodiment of the present invention, the wax flows out from the wax outlet in the middle or side of the bottom area of ​​the mold shell; the wax flows out from the wax outlet in the middle or side of the bottom area of ​​the mold shell by gravity, avoiding the mold shell tilting and causing surface or local cracking of the internal core.

[0132] (5-2) Roasting.

[0133] In an embodiment of the present invention, in order to avoid cracking of the core 1 due to rapid sintering, a segmented continuous sintering method is adopted, which raises the temperature to the second, third and fourth sintering temperatures, and holds the temperature at the second, third and fourth sintering temperatures respectively, and then cools and removes it from the furnace.

[0134] In an embodiment of the present invention, the second calcination temperature is 400℃~500℃, for example, it can be one of 400℃, 420℃, 450℃, 480℃, 500℃ or any value that meets the above range; the holding time at the second calcination temperature is ≥3h, for example, it can be 3h~6h; specifically, the holding time can be one of 3h, 4h, 5h, 6h or any value that meets the above range.

[0135] In embodiments of the present invention, the third calcination temperature is 650°C to 750°C, for example, it can be one of 650°C, 680°C, 700°C, 720°C, and 750°C or any value that satisfies the above range; the holding time at the third calcination temperature is ≥3h, for example, it can be 3h to 6h; specifically, the holding time can be one of 3h, 4h, 5h, and 6h or any value that satisfies the above range.

[0136] In embodiments of the present invention, the fourth calcination temperature is 950℃~1200℃, for example, it can be one of 950℃, 980℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃ or any value satisfying the above range; the holding time at the fourth calcination temperature is ≥3h, for example, it can be 3h~8h; specifically, the holding time can be one of 3h, 4h, 5h, 6h, 7h, 8h or any value satisfying the above range.

[0137] In embodiments of the present invention, the furnace is cooled to room temperature before being removed from the furnace, or cooled to below 300°C before being removed from the furnace. Room temperature refers to a temperature range of 20°C to 30°C.

[0138] Because the dewaxing and firing processes of the mold shell are carried out continuously, the firing temperature is gradually increased in stages. This process removes the wax from the inside of the mold shell and ceramicizes it through high-temperature firing. Furthermore, the gradual heating of the mold shell reduces the risk of core deformation or displacement caused by thermal expansion and contraction during the heating process. Simultaneously, continuous dewaxing and firing improves heating efficiency and effectively reduces the heating and holding time at each stage.

[0139] (6) After the shell is dewaxed and baked, the surface of the core 1 is inspected with an endoscope to prevent cracks from appearing on the surface of the core 1.

[0140] (7) Use an air gun to clean the inside of the shell.

[0141] It should be noted that the term "comprising" and any variations thereof in the specification and claims of this invention are intended to cover non-exclusive inclusion, for example, including a series of components that are not necessarily limited to those explicitly listed, but may include other components that are not explicitly listed or that are inherent to the component.

[0142] In this invention, the terms "upper," "lower," "bottom," "top," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0143] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0144] Furthermore, the descriptions of "first," "second," etc., involved in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0145] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0146] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a shell containing a multi-angle irregularly shaped cavity, characterized in that, It includes the following steps: Prepare a core according to the cavity structure of the casting. The core includes multiple interconnected pipe bodies distributed at multiple angles. Design multiple segmented wax patterns according to the cavity structure of the casting, and assemble the core and the multiple segmented wax patterns so that the core is placed in a multi-angle special-shaped cavity formed by surrounding the multiple segmented wax patterns to obtain a casting wax pattern. Among them, the inner diameters of partial regions of at least part of the pipe bodies of the core are the same as those of the corresponding positions of the multi-angle special-shaped cavity for precise fit, and the remaining partial regions of at least part of the pipe bodies are suspended in the multi-angle special-shaped cavity. The ratio of the distance d between the suspended part of the pipe body and the cavity wall of the multi-angle special-shaped cavity to the wall thickness x of the wax pattern corresponding to the suspended part of the pipe body is: d = kx, where k is a proportionality coefficient. When 1 mm ≤ x ≤ 8 mm, 0.4 ≤ k ≤ 0.5; when 8 mm < x ≤ 20 mm, 0.1 ≤ k ≤ 0.

15. Prepare a surface layer shell and a backing layer shell on the surface of the casting wax pattern in sequence, and then use segmented continuous dewaxing and roasting to obtain the shell containing a multi-angle special-shaped cavity.

2. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 1, characterized in that, The preparation of the surface layer shell includes: Coat the surface of the casting wax pattern with a surface layer slurry, and then remove the excess surface layer slurry. After that, perform surface layer sand pouring, and after drying, form the surface layer shell.

3. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 2, characterized in that, The preparation of the backing layer shell includes: Coat the surface of the surface layer shell with a backing layer slurry, and remove the excess backing layer slurry. After that, perform backing layer sand pouring, and after drying, form the first backing layer shell. Repeat the steps of coating the backing layer slurry and backing layer sand pouring in the preparation of the backing layer shell multiple times to form multiple backing layer shells.

4. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 1, characterized in that, The segmented continuous dewaxing and roasting includes: Dewaxing, heating up to the first roasting temperature, and keeping warm to make the wax liquid flow out from the dewaxing port. Roasting, heating up to the second, third, and fourth roasting temperatures in sequence, and keeping warm at the second, third, and fourth roasting temperatures respectively, and then cooling and taking out of the furnace.

5. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 4, characterized in that, The first roasting temperature is 100°C to 200°C, and the holding time at the first roasting temperature is 3 h to 6 h.

6. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 4, characterized in that, The wax liquid flows out from the wax outlet in the middle or on the side of the bottom area of the shell.

7. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 4, characterized in that, The second roasting temperature is 400°C to 500°C, and the holding time at the second roasting temperature ≥ 3 h.

8. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 4, characterized in that, The third roasting temperature is 650°C to 750°C, and the holding time at the third roasting temperature ≥ 3 h.

9. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 4, characterized in that, The fourth roasting temperature is 950°C to 1200°C, and the holding time at the fourth roasting temperature ≥ 3 h.

10. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 4, characterized in that, Cool in the furnace to room temperature and then take out of the furnace, or cool in the furnace to below 300°C and then take out of the furnace.

11. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 1, characterized in that, When the wall thickness of the casting wax pattern corresponding to the suspended part of the pipe body ≤ 10 mm, the distance between the suspended part of the pipe body and the cavity wall of the corresponding position of the multi-angle special-shaped cavity ≤ 1 mm. When the wall thickness of the casting wax pattern corresponding to the suspended part of the pipe body > 10 mm, the distance between the suspended part of the pipe body and the cavity wall of the corresponding position of the multi-angle special-shaped cavity ≤ 2 mm.

12. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 11, characterized in that, When the wall thickness of the wax mold corresponding to the suspended part of the tube is ≤3 mm, the distance between the suspended part of the tube and the cavity wall of the multi-angle irregular tube at the corresponding position is ≤0.5 mm.

13. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 1, characterized in that, Based on the structure of the casting cavity, multiple segmented wax models are designed, including: The multiple tubes of the core are divided into X tubes, Y tubes, and Z tubes according to the extension direction of the tubes; The multiple segmented wax models are obtained by dividing the wax model at corresponding positions using the plane formed by the center lines of the X tube and the Y tube as the first dividing plane, and the plane formed by the center lines of the X tube and the part of the Z tube connected to the X tube as the second dividing plane, and these segments serve as the bottom wax model, the rear wax model, and the front wax model, respectively.

14. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 13, characterized in that, The bottom wax model is provided with a first pipe groove, the rear wax model is provided with a second pipe groove, and the front wax model is provided with a third pipe groove; the first pipe groove, the second pipe groove, and the third pipe groove together form the multi-angle irregular cavity.

15. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 14, characterized in that, The assembly of the core and the plurality of segmented wax molds includes: The X tube, Y tube and part of the Z tube of the core are placed in the first pipe groove of the bottom wax mold to be positioned in the X, Y and Z directions. The front wax model and the rear wax model are respectively assembled onto the bottom wax model, and the front wax model and the rear wax model are aligned so that a portion of the second pipe groove and a portion of the third pipe groove surround to form a cavity that sleeves a portion of the Z pipe body, and the first pipe groove and a portion of the third pipe groove and a portion of the second pipe groove surround to form a cavity that sleeves the X pipe body, the Y pipe body and a portion of the Z pipe body.

16. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 15, characterized in that, The Z tube body also includes a Z1 tube body connected to the Y tube body, and the rear wax mold is further provided with a through-tube cavity for fitting the Z1 tube body.

17. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 16, characterized in that, A portion of the Z1 tube body has the same inner diameter as the corresponding sleeve cavity for precise fit, while the remaining portion of the Z1 tube body is suspended in the sleeve cavity.

18. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 1, characterized in that, At least a portion of the core tube passes through the inner cavity of the shell and protrudes from the outer side of the shell.

19. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 1, characterized in that, The shell preparation method further includes: After dewaxing and firing, the core is subjected to quality inspection; and the inside of the shell is cleaned.

20. The method for preparing a shell containing a multi-angle irregularly shaped cavity as described in claim 19, characterized in that, An endoscope was used to inspect the interior of the shell.

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