A method and mold for preparing castings with complex cavities

Abstract

This invention relates to the field of metal casting technology, and specifically to a method and mold for preparing castings with complex cavities. The preparation method includes core preparation, wax pattern design, basic wax pattern preparation, integral wax pattern preparation, shell preparation, and melting and pouring. Basic wax pattern preparation includes designing multiple segmented wax patterns according to the cavity structure of the casting. Integral wax pattern preparation includes assembling the core with the multiple segmented wax patterns using splicing fixtures, so that the core is placed within the multi-angle irregular cavity formed by the multiple segmented wax patterns, resulting in the integral wax pattern. At least a portion of the core's tube body has the same inner diameter as the corresponding multi-angle irregular cavity for precise fit, while the remaining portion of the core's tube body is suspended within the multi-angle irregular cavity. The preparation method of this invention ensures both precise fit between the segmented wax patterns and the core, and utilizes the dimensional accuracy of the core to guarantee the dimensional accuracy of the casting's internal cavity later.

Description

Technical Field

[0001] This invention relates to the field of metal casting technology, and specifically to a method for preparing castings with complex cavities and a mold. Background Technology

[0002] Titanium alloy precision castings are widely used in the aerospace, weaponry, and shipbuilding industries. Due to the stringent environmental requirements, high quality is essential for their production. Investment casting, also known as lost-wax casting, is typically employed. This method involves creating a pattern from a fusible material, coating the pattern with several layers of refractory material to form a shell, melting the pattern, removing it from the shell, and then firing it at high temperature to obtain the final casting. Molten metal is then poured into the shell to produce the final casting. The process generally includes wax pressing, shell preparation, dewaxing, molten metal pouring, and post-processing. Therefore, the quality of the titanium alloy shell significantly impacts the final casting quality.

[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.

[0004] During core removal, there may be instances where the core is not completely removed or the inner wall of the casting is damaged. Since the casting is made from a mold shell and is finally formed after the core is removed, the above processes all affect the overall forming, dimensional accuracy, and internal cavity quality of the casting, seriously impacting the reliability of the casting in use.

[0005] Therefore, this invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method and mold for preparing castings with complex cavities. In this method, multiple tubes with multi-angle distribution of the core are used to form a multi-dimensional fit with the segmented wax pattern, which not only ensures the precise fit between the segmented wax pattern and the core, but also ensures the dimensional accuracy of the inner cavity of the casting by utilizing the dimensional accuracy of the core.

[0007] To achieve the above objectives, the present invention provides a method for preparing a casting with a complex cavity, comprising the following steps:

[0008] A core is prepared according to the shape of the casting cavity, the core comprising multiple tubes distributed at multiple angles;

[0009] Multiple segmented wax molds were designed based on the structure of the casting cavity.

[0010] The core and multiple segmented wax molds are assembled using splicing fixtures to form an integral wax mold with multi-angle irregular cavities, and the core is placed inside the multi-angle irregular cavity; wherein, at least a portion of the core tube body has the same inner diameter as the corresponding position of the multi-angle irregular cavity for precise fit, and the remaining portion is suspended in the multi-angle irregular cavity.

[0011] The surface of the integral wax model is coated with a slurry, dried, dewaxed, and fired to form a casting shell.

[0012] The casting shell is melted and poured, and then the internal core is removed to obtain the casting.

[0013] In one specific embodiment of the present invention, melting and pouring a wax model of a casting to obtain a casting includes:

[0014] Castings are poured using a casting mold to obtain castings with a core.

[0015] Remove the core from the casting to obtain a casting with multi-angled cavities.

[0016] In one specific embodiment of the present invention, vibration and grinding are used to remove the core inside the casting.

[0017] In one specific embodiment of the present invention, the mold shell is preheated before casting, and the preheating temperature is between 300-500℃.

[0018] In one specific embodiment of the present invention, the integral wax model surface is coated with a slurry, and after drying, a shell is formed, comprising:

[0019] Surface shell preparation: Apply a surface layer slurry to the surface of the integral wax model, and then remove the excess surface layer slurry;

[0020] The overall wax model is subjected to surface sanding and dried to form a surface shell.

[0021] Preparation of back layer shell: The surface of the surface layer shell is coated with back layer slurry, and excess back layer slurry is removed; then the back layer is sandblasted, and after drying, the back layer shell is formed.

[0022] The back-shell preparation steps are repeated multiple times to form a multi-layered back-shell.

[0023] In one specific embodiment of the present invention, the shell dewaxing includes:

[0024] After heating to the dewaxing temperature, the temperature is maintained so that the wax flows out from the dewaxing port, and then the mold shell is cooled to room temperature with the furnace.

[0025] Preferably, the dewaxing temperature is 100-250°C and the holding time is 3-8 hours; preferably, the wax flows out from the wax outlet in the middle or side of the bottom area of ​​the mold shell.

[0026] In one specific embodiment of the present invention, the shell calcination includes:

[0027] After heating to the first, second, and third firing temperatures, hold the temperature at each temperature, and then cool and remove from the oven.

[0028] Preferably, the first calcination temperature is 500-600℃, and the holding time is ≥3h; the holding time is preferably 3-6h.

[0029] Preferably, the second calcination temperature is 600–800℃, and the holding time is ≥3h; the holding time is preferably 3–8h.

[0030] Preferably, the third calcination temperature is 900–1200℃, and the holding time is ≥3h; the holding time is preferably 4–12h.

[0031] Preferably, the cooling process can involve cooling the furnace to room temperature before unloading, or cooling the furnace to below 450°C before unloading.

[0032] In one specific embodiment of the present invention, the design of multiple segmented wax molds based on the cavity structure of the casting includes:

[0033] The core tube is divided into X tube, Y tube, and Z tube according to the extension direction;

[0034] The plane formed by the center lines of the X tube and the Y tube is used 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 is used as the second dividing plane. Multiple segmented wax models are obtained at the corresponding positions of the casting wax model, and they are respectively used as the bottom wax model, the rear wax model and the front wax model.

[0035] Preferably, the bottom wax mold is provided with a first pipe groove, the rear wax mold is provided with a second pipe groove, and the front wax mold 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.

[0036] In one specific embodiment of the present invention, when the wall thickness of the casting wax mold corresponding to the suspended part of the tube body is ≤10mm, 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 ≤1mm;

[0037] When the wall thickness of the casting wax mold corresponding to the suspended part of the tube body is >10mm, 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 ≤2mm.

[0038] Preferably, 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.

[0039] In one specific embodiment of the present invention, the splicing fixture includes a base plate with a fixing ring, a sliding plate slidably connected to the base plate, and a top pressure plate corresponding to the fixing ring;

[0040] The assembly of the core and multiple segmented wax molds using splicing fixtures includes the following steps:

[0041] Rear wax model fixing: The rear wax model is installed on the fixing ring of the base plate accordingly;

[0042] Core fixing: Place the X tube, Y tube and Z tube of the core into the second core groove of the rear wax mold;

[0043] Front wax mold fixing: The front wax mold is installed on the rear wax mold, and part of the third core groove and part of the second core groove are enclosed to form a cavity that sleeves part of the Z tube body;

[0044] Bottom wax mold fixing: Place the bottom wax mold on the sliding plate and push the sliding plate to splice the bottom wax mold with the rear wax mold and the front wax mold, and make the first pipe groove and part of the third core groove and part of the second core groove surround to form a cavity for sleeve of the X tube body and Z tube body;

[0045] Top pressure plate fixing: Install top pressure plates on the front wax mold and bottom wax mold, connect them to the fixing rings with screws, and fix them with nuts;

[0046] Melting and fixing: melting at least a portion of the joints between the base wax model, the rear wax model, and the front wax model to fuse them together.

[0047] In one specific embodiment of the present invention, the splicing fixture further includes a plurality of support columns disposed on the outer periphery of the fixing ring, the support columns being used to support the second pipe groove of the rear wax mold; and / or

[0048] The sliding plate is provided with a positioning block, a support block, and a side baffle. The bottom wax mold is mounted on the sliding plate via the positioning block, the support block, and the side baffle; and / or

[0049] The fixing ring has a screw hole, and the top plate has a bolt. The bolt passes through the center hole of the front and rear films and the rear wax mold and is bolted to the screw hole. The top plate is fixed with the nut on the bolt, and the front and rear films and the rear wax mold are fixed.

[0050] 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.

[0051] 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.

[0052] In this invention, a core is used to assemble the bottom wax mold, the rear wax mold, and the front wax mold with the help of splicing fixtures, which can improve splicing efficiency and splicing accuracy.

[0053] This invention enhances the stability of the mold shell and internal core through the fixing effect of the coating zone. During the casting process, when molten metal is poured into the mold shell, the coating zone and casting equipment are fixed, while the core portion protruding from the outer side of the mold shell is directly connected to the coating zone. This enhances the stability of the core under the impact of molten metal, preventing displacement that could affect the internal dimensions of the casting. Simultaneously, during centrifugal casting, it prevents the mold shell from shifting position on the centrifugal disc due to centrifugal force, thus preventing turbulent flow of the molten metal or incomplete filling. Attached Figure Description

[0054] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0055] Figure 1-2 This is a schematic diagram of the overall structure of the casting wax model from different perspectives in an embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of the core structure in an embodiment of the present invention;

[0057] Figure 4 for Figure 1 Schematic diagram of the midsole wax model;

[0058] Figure 5-6 for Figure 1 Schematic diagram of the structure of the front and middle wax mold;

[0059] Figure 7-8 for Figure 1 Schematic diagram of the structure of the mid-to-late stage wax model;

[0060] Figure 9 This is a schematic diagram of the splicing tooling in an embodiment of the present invention;

[0061] Figure 10-13 This is a schematic diagram showing the fit between the splicing tooling and the casting wax model in an embodiment of the present invention.

[0062] Explanation of reference numerals in the attached figures:

[0063] 1-core; 11-X pipe body; 12-Y pipe body; 13-Z pipe body; 14-Z1 pipe body; 15-Z2 pipe body; 16-Z3 pipe body; 17-Z4 pipe body;

[0064] 2- Bottom wax mold, 21- First pipe groove, 22- First positioning protrusion, 23- Second positioning protrusion;

[0065] 3-Rear wax mold, 31-Second pipe groove, 32-Through-sleeve cavity;

[0066] 4-Front wax model, 41-Third pipe groove;

[0067] 5-Assembly fixture, 51-Base plate, 511-Fixing ring, 512-Support column, 513-Second slide rail, 52-Sliding plate, 53-Top pressure plate, 54-Support block, 55-Positioning block, 56-Side baffle, 57-Screw. Detailed Implementation

[0068] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0069] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0070] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0071] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0072] like Figure 1-13 As shown, the method for preparing a casting with a complex cavity according to the first aspect of the present invention includes the following steps:

[0073] Step 100: Core Preparation

[0074] The core preparation includes preparing core 1 according to the shape of the casting cavity, core 1 including multiple tubes distributed at multiple angles.

[0075] Furthermore, to facilitate the fixing of the core 1 to the subsequent shell, the length of some tubes is greater than the corresponding cavity length, so that the tubes can be exposed during the preparation of the shell.

[0076] Step 200: Wax Model Design

[0077] The wax model of the casting is divided into a bottom wax model 2, a rear wax model 3 and a front wax model 4. A first pipe groove 21 is formed on the bottom wax model 2, a second pipe groove 31 is formed on the rear wax model 3, and a third pipe groove 41 is formed on the front wax model 4.

[0078] Specifically, according to the extension direction, the tube body of the core 1 is divided into X tube body 11, Y tube body 12, and Z tube body 13; X tube body 11, Y tube body 12, and Z tube body 13 represent the three-dimensional coordinate axes X-axis, Y-axis, and Z-axis where the tube body is located, and there is at least one of each type of X tube body, Y tube body, and Z tube body; the bottom wax model 2 is separated at the corresponding position of the casting wax model by the plane formed by the center line of X tube body 11 and Y tube body 12; the remaining wax model is divided into the rear wax model 3 and the front wax model 4 at the corresponding position of the casting wax model by the plane formed by the center line of X tube body 11 and the part of Z tube body 13 connected to X tube body 11.

[0079] 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.

[0080] In the bottom wax model 2, the rear wax model 3, and the front wax model 4, the planes corresponding to the separating surfaces are the splicing surfaces. The multi-dimensional cavities form grooves on the corresponding splicing surfaces. The diameter of the grooves is reset as needed, ensuring that the groove diameter at the cavity port is the same as the tube diameter corresponding to the core 1, facilitating a precise fit with the core 1 during subsequent assembly. The groove diameters at other locations are larger than the tube diameter so that the core 1 is suspended above the cavity during subsequent assembly, thus forming the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41.

[0081] Specifically, when the wall thickness h of the wax model corresponding to the suspended portion of the pipe body is ≤3mm, the distance l between the suspended portion of the pipe body and the walls of the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41 is ≤0.5mm. When the wall thickness h of the wax model corresponding to the suspended portion of the pipe body is 3mm≤h≤10mm, the distance l between the suspended portion of the pipe body and the walls of the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41 is ≤1mm; when the wall thickness h of the wax model corresponding to the suspended portion of the pipe body is >10mm, the distance l between the suspended portion of the pipe body and the walls of the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41 is ≤2mm.

[0082] By precisely fitting a portion of the core 1 tube body with the inner diameter of the corresponding multi-angle cavity, and by suspending a portion of the tube body in the multi-angle cavity, the precision requirements for the casting wax model of the multi-angle cavity are reduced, the assembly difficulty of the casting wax model and the core 1 is reduced, and the problem of the core 1 being unable to be assembled with the pipe groove in a certain dimension due to the multi-angle cavity is avoided.

[0083] To facilitate the positioning of the bottom wax model 2, the rear wax model 3, and the front wax model 4, the splicing surface of the bottom wax model 2 is provided with a first positioning protrusion 22 and a second positioning protrusion 23. The rear wax model 3 is provided with a positioning hole that matches the first positioning protrusion 22, and the front wax model 4 is provided with a positioning hole that matches the second positioning protrusion 23.

[0084] It should be noted that when designing the dividing surface, the tube with the most connected tubes in core 1 can be designated as tube X 11. Then, tube Y 12 and tube Z 13 are set based on tube X 11.

[0085] It should be noted that the X-tube 11 is not necessarily a single tube, but can be multiple continuous tubes. In this embodiment, the X-tube 11 includes connected X1 tubes and X2 tubes, which are arranged at an obtuse angle. The Y-tube 12 includes a Y1 tube connected to the X1 tube and a Y2 tube connected to the X2 tube. The Z-tube 13 includes a Z1 tube 14 connected to the X1 tube and the Y1 tube, and a Z2 tube 15 connected to the X2 tube and the Y2 tube.

[0086] It should be noted that the X tube 11, Y tube 12, and Z tube 13 in this invention are not necessarily perpendicular to each other. That is, the X tube 11, Y tube 12, and Z tube 13 can be perpendicular to each other or set at an angle of 0-90°. For example, the Z tube 13 also includes a Z4 tube 17 connected to the connection position of the X1 tube and the X2 tube. Correspondingly, the bottom wax mold 2 and the rear wax mold 3 are also provided with corresponding limiting grooves.

[0087] It should be noted that the Y tube 12 and Z tube 13 in this invention are not necessarily connected to the X tube 11. For example, the Z tube 13 also includes the Z3 tube 16 connected to the Y tube 12. The wax mold 3 is also provided with a through-tube cavity 32 for fitting the Z3 tube 16. A portion of the Z3 tube 16 has the same inner diameter as the corresponding through-tube cavity 32 for precise fit. The remaining portion of the Z3 tube 16 is suspended in the through-tube cavity 32.

[0088] It should be noted that the length of the tube body in the portion used for precise fitting with the multi-angled lumen is ≥8mm.

[0089] It should be noted that the tube body includes a connecting end for connecting to each other and a free end relative to the connecting end. In this method, a portion of the tube body for precise fitting with the multi-angle cavity is located near the free end; in other embodiments, the portion of the tube body for precise fitting with the multi-angle cavity may also be located near the connecting end.

[0090] It should be noted that, since the X-tube 11, Y-tube 12, and Z-tube 13 of the core are located on different planes, assembly interference is unavoidable when assembling the bottom wax model 2, front wax model 4, rear wax model 3, and core 1. For example, after the X-tube 11 and Y-tube 12 are assembled with the bottom wax model 2, due to the shrinkage and deformation of the wax model, the front wax model 4 and rear wax model 3 cannot be assembled with the X-tube 11 and Y-tube 12 simultaneously with the Z-tube 13 in multiple directions. In this case, the gap between the suspended part of the tube and the cavity wall of the multi-angled cavity can be used as space to adjust the interference.

[0091] Step 300: Preparation of the basic wax model

[0092] Wax molds are prepared based on the designed base wax mold 2, rear wax mold 3, and front wax mold 4. The base wax mold 2, rear wax mold 3, and front wax mold 4 can be prepared by 3D printing. The basic wax mold prepared by 3D printing has an outline that meets the design requirements and has a hollow internal structure to reduce the overall weight of the 3D printed wax mold.

[0093] Clean the bottom wax model 2, the rear wax model 3, and the front wax model 4, and perform local surface repairs.

[0094] Step 400: Preparation of the overall wax model

[0095] The core 1 is assembled with the bottom wax model 2, the rear wax model 3, and the front wax model 4 using the splicing fixture 5, and the core 1 is placed in the multi-angle cavity formed by the first pipe groove 21, the second pipe groove 31, and the third pipe groove 41 to obtain an overall wax model with a multi-angle cavity; and at least a part of the tube body of the core 1 has the same inner diameter as the corresponding multi-angle cavity for precise fit, and the remaining part of the core 1 is suspended in the multi-angle cavity.

[0096] Specifically, the splicing fixture 5 includes a base plate 51 with a fixing ring 511, a sliding plate 52 slidably connected to the base plate 51, and a top pressure plate 53 corresponding to the fixing ring 511.

[0097] The process of assembling the core 1 with the bottom wax model 2, the rear wax model 3, and the front wax model 4 using the splicing fixture 5 includes the following steps:

[0098] Fixing the rear wax model 3: The rear wax model 3 is installed on the fixing ring 511 of the base plate 51; wherein, the shape of the fixing ring 511 is adapted to the shape of the center hole of the rear wax model 3, so that the rear wax model 3 can be placed on the base plate 51 with the splicing surface facing upward.

[0099] At this time, the X and Y directions of the rear wax mold 3 are fixed because they are in contact with the fixing ring 511. The Z direction is further limited by the support column 512 to ensure that the rear wax mold 3 is accurately positioned in the X, Y and Z directions.

[0100] Core 1 fixing: The X tube 11, Y tube 12 and Z tube 13 of the core 1 are placed in the second pipe groove 31 of the rear wax mold 3, the Z3 tube 16 is sleeved in the through tube cavity 32 of the rear wax mold 3, and the Z4 tube 17 is located in the limiting groove of the rear wax mold 3, so that the XYZ directions of the core 1 are all positioned and connected to the rear wax mold 3.

[0101] Front wax mold 4 is fixed: the front wax mold 4 is installed on the rear wax mold 3, and part of the third pipe groove 41 and part of the second pipe groove 31 are enclosed to form a cavity for the sleeve part of the Z pipe body 13; the Z direction of the spliced ​​rear wax mold 3 and the front wax mold 4 is limited by the support column 512, so as to achieve accurate positioning of the spliced ​​rear wax mold 3 and the front wax mold 4 in the XYZ directions.

[0102] Fixing the bottom wax mold 2: Place the bottom wax mold 2 on the sliding plate 52 and push the sliding plate 52 to splice the bottom wax mold 2 with the rear wax mold 3 and the front wax mold 4, so that the first pipe groove 21, part of the third pipe groove 41 and part of the second pipe groove 31 surround and form a cavity for sleeved X tube body 11 and Z tube body 13, and Z4 tube body 17 is located in the limiting groove of the bottom wax mold 2. Specifically, the base plate 51 is provided with a second slide rail 513 and a slider slidably connected to the second slide rail 513. The sliding plate 52 is connected to the slider to slide relative to each other on the base plate 51. The bottom wax mold 2 is fixed at a preset angle by the positioning block 55, the support block 54 and the side baffle 56 provided on the sliding plate 52. Since the bottom wax mold 2 is fixed at a preset angle after positioning, the positioning accuracy of the rear wax mold 3 and the front wax mold 4 can be ensured during the splicing process, and it is easier to assemble with the rear wax mold 3 and the front wax mold 4 by the sliding device on the sliding plate 52.

[0103] During assembly, the first positioning protrusion 22 and the second positioning protrusion 23 on the bottom wax mold 2 are respectively matched and positioned with the positioning holes at the corresponding positions of the front wax mold 4 and the rear wax mold 3, further ensuring assembly accuracy.

[0104] Top pressure plate 53 fixing: After the bottom wax mold 2, front wax mold 4, and rear wax mold 3 are assembled into a whole, the top pressure plate 53 is installed on the front wax mold 4 and bottom wax mold 2, and connected to the fixing ring 511 by screws 57. Specifically, the fixing ring 511 has threaded holes, the top pressure plate 53 has through holes, and screws 57 are inserted into the through holes of the top pressure plate 53. The screws 57 pass through the center holes of the rear wax mold 3 and the front wax mold 4 in sequence to connect with the threaded holes on the fixing ring 511. The top pressure plate 53 and the fixing ring 511 are locked together by using nuts above the through holes of the top pressure plate 53, thereby achieving a tight splicing of the bottom wax mold 2, front wax mold 4, and rear wax mold 3. At this time, the combined action of the top pressure plate 53 and the support column 512 further ensures accurate positioning of the spliced ​​bottom wax mold 2, front wax mold 4, and rear wax mold 3 in the XYZ directions.

[0105] Enclosure fixing: An elastic envelope is used to fit onto the outside of the tubular splicing structure formed by the first pipe groove 21, the second pipe groove 31 and / or the third pipe groove 41; the envelope is made of elastic material and can tightly fix at least two segmented wax molds and the core 1.

[0106] Melting and fixing: At least part of the joints between the base wax model 2, the rear wax model 3, and the front wax model 4 are melted and fused together. Specifically, the joints can be melted with a soldering iron to achieve the melting and fusion connection of the wax models, the rear wax model 3, and the front wax model 4.

[0107] It should be noted that the splicing fixture 5 also includes multiple support columns 512. The support columns 512 are disposed on the outer periphery of the fixing ring 511 and are used to support the second pipe groove 31 of the rear wax mold 3. In this embodiment, there are four support columns 512, which are respectively disposed at the pipe ends of the X1 pipe body, X2 pipe body, Y1 pipe body and Y2 pipe body.

[0108] Step 500: Shell Preparation

[0109] Surface shell preparation

[0110] A surface layer slurry is applied to the surface of the wax model of the casting, and then the excess surface layer slurry is removed; then a surface layer sand is applied, and after drying, a surface layer shell is formed.

[0111] The preparation of the back shell includes:

[0112] The surface of the shell is coated with the back layer slurry, and the excess back layer slurry is removed; then the back layer is sand-sprayed, and after drying, the first back layer shell is formed.

[0113] The back layer slurry coating and back layer sanding steps in the preparation of the back layer shell are repeated multiple times to form a multi-layer back layer shell.

[0114] 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 casting shell.

[0115] 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.

[0116] In one specific embodiment of the present invention, the shell dewaxing includes:

[0117] After heating to the dewaxing temperature, the temperature is maintained so that the wax flows out from the dewaxing port, and then the mold shell is cooled to room temperature with the furnace.

[0118] Preferably, the dewaxing temperature is 100–250°C, and the holding time is 3–8 hours;

[0119] Preferably, the wax flows out from the wax outlet in the middle or side of the bottom area of ​​the mold shell.

[0120] In one specific embodiment of the present invention, the segmented shell calcination includes:

[0121] After heating to the first, second, and third firing temperatures, hold the temperature at each temperature, and then cool and remove from the oven.

[0122] Preferably, the first calcination temperature is 500-600℃, and the holding time is ≥3h; the holding time is preferably 3-6h.

[0123] Preferably, the second calcination temperature is 600–800℃, and the holding time is ≥3h; the holding time is preferably 3–8h.

[0124] Preferably, the third calcination temperature is 900–1200℃, and the holding time is ≥3h; the holding time is preferably 4–12h.

[0125] Preferably, the cooling process can involve cooling the furnace to room temperature before unloading, or cooling the furnace to below 450°C before unloading.

[0126] In some embodiments of the present invention, the dewaxing temperature is 100-250°C and the holding time is 3-8 hours.

[0127] For example, the dewaxing temperature is one of 100℃, 110℃, 117℃, 150℃, 250℃, or any value within the above range. The holding time is one of 3, 4, 5, 6, 7, 7.3, 7.5, 8 hours, or any value within the above range. Preferably, after dewaxing and before firing, the tube body of the core that passes through the inner cavity of the mold shell and protrudes outside the mold shell of the casting is covered with the same material as the mold shell, and the covered area connects to part of the mold shell.

[0128] After dewaxing the mold shell and before firing, the tube body of the core that passes through the inner cavity of the mold shell and protrudes outside the mold shell of the casting is covered. This can avoid the situation where the dewaxing temperature is too low, and the covered area can only be partially dried and cannot be ceramicized when heated at this temperature. The heating and cooling process of dewaxing involves the thermal expansion and contraction of the covered area, which makes it impossible for the covered area to be completely connected with the mold shell and the tube body of the core that protrudes outside the mold shell.

[0129] After the shell is fired, use an endoscope to inspect the inner cavity of the shell and the surface of the core 1 to prevent cracking.

[0130] The inside of the casting mold shell is cleaned by blowing air with an air gun.

[0131] Step 600 and smelting and casting

[0132] Casting is performed using a casting mold shell to obtain a casting with core 1; before pouring the molten metal, the mold shell is preheated, and the preheating temperature is between 300-500℃ to ensure the stability of the mold shell.

[0133] Preferably, the shell covering area can serve as the fixing area between the shell and the casting equipment.

[0134] The stabilizing effect of the coating zone enhances the stability of the mold shell and internal core. During the casting process, when molten metal is poured into the mold shell, the coating zone and the casting equipment are fixed, while the core portion protrudes from the outside of the mold shell and is directly connected to the coating zone. This enhances the stability of the core under the impact of molten metal, preventing displacement that could affect the internal dimensions of the casting. Furthermore, for centrifugal casting, it prevents the mold shell from shifting position on the centrifugal disc due to centrifugal force during centrifugal casting, thus preventing turbulent flow of the molten metal or incomplete filling.

[0135] Preferably, the casting is performed by gravity or centrifugal casting.

[0136] Remove the core 1 from the casting to obtain a casting with multi-angled cavities. Specifically, remove the core 1 from the casting using vibration or corrosion. Remove any remaining core 1 inside the casting by grinding.

[0137] Furthermore, after the casting is poured, the internal core 1 of the casting is removed.

[0138] A second aspect of the present invention also provides a shell mold, which is mainly prepared using the shell preparation method described above. Since the shell mold in this embodiment shares the same technical concept as the preparation method described above, it also possesses the beneficial effects of the preparation method described above.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a casting with complex tubular cavities, characterized in that, Includes the following steps: A core is prepared according to the shape of the casting cavity, the core comprising multiple interconnected tubes distributed at multiple angles; Multiple segmented wax molds were designed based on the cavity structure of the casting. The core and multiple segmented wax molds are assembled using splicing fixtures to form an integral wax mold with multi-angle irregular cavities, and the core is placed inside the multi-angle irregular cavity; wherein, at least a portion of the core tube body has the same inner diameter as the corresponding position of the multi-angle irregular cavity for precise fit, and the remaining portion is suspended in the multi-angle irregular cavity. The surface of the integral wax model is coated with a slurry, dried, dewaxed, and fired to form a casting shell. The casting shell is melted and poured, and then the internal core is removed to obtain the casting. When the wall thickness of the casting wax model corresponding to the suspended part of the tube body is ≤10mm, 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 ≤1mm. When the wall thickness of the casting wax model corresponding to the suspended part of the tube body is >10mm, 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 ≤2mm. 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.

2. The method for preparing a casting with complex cavities according to claim 1, characterized in that, The process of melting and pouring the wax model of the casting to obtain the casting includes: Castings are poured using a casting mold to obtain castings with a core. Remove the core from the casting to obtain a casting with multi-angled cavities.

3. The method for preparing a casting with complex cavities according to claim 2, characterized in that, The core inside the casting is removed by vibration and grinding; and / or The mold shell is preheated before casting, with a preheating temperature between 300-500℃.

4. The method for preparing a casting with complex cavities according to claim 2, characterized in that, The process of coating the surface of the integral wax model with a slurry and drying it to form a shell includes: Surface shell preparation: Apply a surface layer slurry to the surface of the integral wax model, and then remove the excess surface layer slurry; The overall wax model is subjected to surface sanding and dried to form a surface shell. Preparation of back layer shell: The surface of the surface layer shell is coated with back layer slurry, and excess back layer slurry is removed; then the back layer is sandblasted, and after drying, the back layer shell is formed. The back-shell preparation steps are repeated multiple times to form a multi-layered back-shell.

5. The method for preparing a casting with complex cavities according to claim 1, characterized in that, The shell dewaxing process includes: After heating to the dewaxing temperature, the temperature is maintained so that the wax flows out from the dewaxing port, and then the mold shell is cooled to room temperature with the furnace. The dewaxing temperature is 100~250℃, and the holding time is 3~8h; the wax flows out from the wax outlet in the middle or side of the bottom area of ​​the mold shell; and / or The shell baking includes: After heating to the first, second, and third firing temperatures, hold the temperature at each temperature, and then cool and remove from the oven. The first calcination temperature is 500~600℃, and the holding time is ≥3h; The second calcination temperature is 600~800℃, and the holding time is ≥3h; The third calcination temperature is 900~1200℃, and the holding time is ≥3h; The cooling process can involve cooling the furnace to room temperature before unloading, or cooling the furnace to below 450°C before unloading.

6. The method for preparing a casting with complex cavities according to claim 1, characterized in that, Based on the structure of the casting cavity, multiple segmented wax models are designed, including: The core tube is divided into X tube, Y tube, and Z tube according to the extension direction; The plane formed by the center lines of the X tube and the Y tube is used 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 is used as the second dividing plane. Multiple segmented wax models are obtained at the corresponding positions of the casting wax model, and they are respectively used as the bottom wax model, the rear wax model and the front wax model. 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.

7. The method for preparing a casting with complex cavities according to claim 6, characterized in that, The splicing fixture includes a base plate with a fixing ring, a sliding plate slidably connected to the base plate, and a top pressure plate corresponding to the fixing ring; The assembly of the core and multiple segmented wax molds using splicing fixtures includes the following steps: Rear wax model fixing: The rear wax model is installed on the fixing ring of the base plate accordingly; Core fixing: Place the X tube, Y tube and Z tube of the core into the second pipe groove of the rear wax mold; Front wax mold fixing: The front wax mold is installed on the rear wax mold, and part of the third pipe groove and part of the second pipe groove are enclosed to form a cavity that sleeves part of the Z-tube body; Bottom wax mold fixing: Place the bottom wax mold on the sliding plate and push the sliding plate to splice the bottom wax mold with the rear wax mold and the front wax mold, and make the first pipe groove and part of the third pipe groove and part of the second pipe groove surround to form a cavity for sleeved X pipe body and Z pipe body; Top pressure plate fixing: Install top pressure plates on the front wax mold and bottom wax mold, connect them to the fixing rings with screws, and fix them with nuts; Melting and fixing: melting at least a portion of the joints between the base wax model, the rear wax model, and the front wax model to fuse them together.

8. The method for preparing a casting with complex cavities according to claim 7, characterized in that, The assembly fixture also includes multiple support columns, which are disposed on the outer periphery of the fixing ring and are used to support the second pipe groove of the rear wax mold; and / or The sliding plate is provided with a positioning block, a support block, and a side baffle. The bottom wax mold is mounted on the sliding plate via the positioning block, the support block, and the side baffle; and / or The fixing ring has a screw hole, and the top pressure plate has a bolt. The bolt passes through the center hole of the front wax model and the rear wax model and is bolted to the screw hole. The top pressure plate is fixed with the nut on the bolt, and the front wax model and the rear wax model are fixed.

9. A casting mold with complex cavities, characterized in that, It is prepared by the casting preparation method according to any one of claims 1-8.

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