A wax pattern tree structure for investment precision casting of titanium alloy joints and a manufacturing method thereof

Abstract

The present invention relates to the technical field of titanium alloy investment casting process, specifically a wax mold tree structure for titanium alloy joint investment precision casting and a manufacturing method thereof, comprising a sprue arranged along the length direction of the casting wax mold, one end of the sprue connected to the runner, the runner arranged in a direction perpendicular to the sprue, an entgate arranged parallel to the sprue, one end of the entgate connected to the end of the runner away from the sprue, the end of the entgate away from the runner connected to the casting wax mold, an exhaust device arranged at the top of the casting wax mold, and a slag collecting ball arranged at the bottom of the casting wax mold. The present invention adopts the design of the slag collecting ball at the bottom, so that impurities and slag can be effectively settled and collected in the slag collecting ball to avoid entering the main body of the casting, so that the slag inclusion size of the casting is reduced from 0.5~3mm of the traditional technology to ≤0.1mm, and the slag inclusion rate is reduced from 3.2-4.5% to ≤0.8%, and the slag collection efficiency is as high as 99.5%, which greatly improves the internal quality and surface finish of the casting.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy investment casting technology, in particular to a wax pattern tree structure for titanium alloy joint investment precision casting and a manufacturing method thereof. Background Art

[0002] Titanium alloys are widely used in modern industries such as aerospace due to their low density, high specific strength, high-temperature resistance, and corrosion resistance. Investment casting is a key technology for manufacturing complex titanium alloy components. However, titanium alloys have a high melting point (1660-1800°C), poor fluidity (melt viscosity is approximately 10-20 times that of steel), and are prone to reacting with gases such as oxygen and nitrogen to form inclusions, resulting in a high rate of casting defects.

[0003] The joint is one of the important components of aerospace equipment. Its main functions are connection and load-bearing. It is a casting product commonly encountered in the field of investment casting in the aerospace industry. The part has a double-pronged structure with an overall size of 220×150×80mm. The wall thickness of the double-pronged connecting flange is 17~20mm. The flange and double-pronged head of this part are important parts that cooperate with other load-bearing parts, so strict requirements are placed on mechanical properties, geometric accuracy and surface quality.

[0004] In titanium alloy investment casting, traditional bottom pouring systems are prone to casting defects such as shrinkage cavities and porosity. While top pouring systems offer shorter filling times and better shrinkage compensation, they also present challenges such as increased turbulence and impurity dispersion. The probability of slag inclusion in joint products can reach as high as 25-45%, directly impacting bearing performance (e.g., a 15-20% decrease in tensile strength). This severely limits the quality and reliability of titanium alloy castings, increasing production costs and scrap rates.

[0005] Publication No.: CN115319026B A method for exhausting and filling a mold shell for investment counter-gravity casting of an aluminum alloy, comprising: step S1, using a mold to press out an exhaust runner with stepped exhaust;

[0006] In step S2, the vent runner is affixed to the wax mold that will form the casting after the gating system is prepared. In step S3, the wax mold with the vent runner is molded into a shell and dewaxed. The casting cavity within the shell corresponds to the wax mold before dewaxing, and the vent channel within the shell corresponds to the vent runner before dewaxing. However, this solution uses a top-venting and bottom-metal injection structure, which can easily lead to casting defects such as shrinkage cavities and porosity.

[0007] Therefore, there is an urgent need for a new wax pattern tree structure for investment precision casting of titanium alloy joints and a manufacturing method thereof to solve the problems of difficult control of titanium liquid flow and difficult removal of impurities in the casting of titanium alloy joints. Summary of the Invention

[0008] In view of this, the present invention aims to propose a wax pattern tree structure for investment precision casting of titanium alloy joints and a manufacturing method thereof, so as to solve the problems of difficulty in controlling the flow of titanium liquid and removing impurities in the casting of titanium alloy joints.

[0009] In view of the problems of shrinkage cavities and shrinkage in traditional bottom pouring systems, as well as the shortcomings of top pouring systems such as increased turbulence and impurity dispersion, the present invention proposes an innovative solution. Through the collaborative design of "equal-section runner + bottom slag collecting ball + top exhaust needle", the difficult problems of titanium liquid flow control and impurity removal in titanium alloy joint casting are solved, and the quality of castings and production efficiency are improved. The slag collecting ball can effectively collect impurities to prevent them from entering the main body of the casting, significantly reducing the slag inclusion rate and improving the purity and mechanical properties of the casting. This not only ensures short filling time and good shrinkage compensation effect, but also solves the problem of impurity dispersion.

[0010] The technical solution of the present invention is achieved as follows:

[0011] One object of the present invention is to disclose a wax pattern tree structure for investment precision casting of a titanium alloy joint, comprising a sprue, a runner, an ingrate, an exhaust device and a slag collecting ball;

[0012] The sprue is arranged along the length direction of the casting wax mold, one end of the sprue is connected to the runner, and the sprue is used to guide the titanium alloy liquid to flow smoothly from the ladle into the runner and the ingrown;

[0013] The runner is arranged in a direction perpendicular to the sprue, and is used to evenly distribute the titanium alloy liquid flowing from the sprue to each of the ingrowns;

[0014] The ingrown is arranged in parallel with the sprue, and at least two ingrowns are provided. One end of the ingrown is connected to the end of the runner away from the sprue, and the other end of the ingrown is connected to the casting wax mold. The ingrown is used to guide the titanium alloy liquid from the runner to the casting wax mold and control the flow state of the titanium alloy liquid;

[0015] The exhaust device is arranged at the top of the casting wax mold and is used for exhausting and removing slag at a high superheat during the pouring process;

[0016] The slag collecting balls are arranged at the bottom of the casting wax mold and are used for settling and collecting impurities.

[0017] Furthermore, the sprue, the runner and the ingrown runner adopt a topological design, and the three use a "1-1-N" topological layout, where N≥4.

[0018] Furthermore, the sprue cross section S1 = the runner cross section S2 = ∑ the ingrate cross section S3, which is verified by the formula: S1 = πD2 / 4=W×H=n×πd 2 / 4;

[0019] Wherein: D is the diameter of the sprue;

[0020] W×H is the width×height of the runner;

[0021] n is the number of ingates;

[0022] d is the diameter of the single sprue.

[0023] Furthermore, the sprue is a column with a diameter of Φ30-50 mm.

[0024] Furthermore, the length of the runner L=N×l, where l=1.2-1.5 times the shortest projection length of the joint.

[0025] Furthermore, the ingrown channel is set at an inclination angle of 15-25 degrees, so that the titanium alloy liquid is injected along the tangent direction of the cavity wall to reduce turbulence.

[0026] Furthermore, 2-4 exhaust devices are provided, and each exhaust device is a round rod with a diameter of Φ3mm, a height of 30-50mm, and a slope of 1-1.5°.

[0027] Furthermore, the diameter of the slag collecting ball is D'=Φ20-30 mm, the neck diameter is d'=Φ10-15 mm, and the neck height is h'=0.8-1.5 d'.

[0028] Furthermore, the exhaust device and the slag collecting ball are made of the same wax as the runner wax, and the exhaust device and the slag collecting ball are respectively connected to the casting wax mold by group welding.

[0029] Another object of the present invention is a method for manufacturing a wax pattern tree for investment casting of a titanium alloy joint, which is used to manufacture any of the above-mentioned wax pattern tree structures for investment casting of a titanium alloy joint, and specifically comprises the following steps:

[0030] S1: Design and preparation: Design the positions and sizes of the sprue, runner, ingates, exhaust device, slag collecting balls and casting wax mold according to the specific requirements of the casting;

[0031] S2: Making wax model components: using a wax injection machine to inject wax into the mold to form a wax model of the desired shape;

[0032] S3: Assembling the wax model tree: fixing the prepared sprue, runner, ingates, exhaust device and slag collecting ball on the casting wax model to form a complete wax model tree structure.

[0033] Compared with the prior art, the wax pattern tree structure for investment precision casting of a titanium alloy joint of the present invention and the manufacturing method thereof have the following advantages:

[0034] 1. The present invention uses the design of the slag collecting ball at the bottom to effectively settle and collect impurities and slag in the slag collecting ball, preventing it from entering the main body of the casting. This reduces the slag inclusion size of the casting from 0.5-3mm in traditional technology to ≤0.1mm, and the slag inclusion rate from 3.2-4.5% to ≤0.8%. The slag collection efficiency is as high as 99.5%, greatly improving the internal quality and surface finish of the casting.

[0035] 2. This invention utilizes a topological design of "constant cross-section runner + single sprue - single runner and multiple ingates," and features ingates with specific angles. This facilitates smooth injection of the titanium melt along the tangent of the cavity wall, reducing turbulence and ensuring stable melt flow and rapid mold filling. Furthermore, the top vent pin design further enhances degassing and slag removal during the pouring process, reducing the likelihood of casting defects.

[0036] 3. The present invention effectively isolates impurities by collecting slag balls, eliminating the need for additional manual finishing and cleaning of castings, achieving 0 hours of labor time for finishing, greatly improving production efficiency, reducing scrap rate and production costs, and is particularly suitable for large-scale industrial production needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0038] Figure 1 It is a schematic diagram of the wax pattern structure of the present invention;

[0039] Figure 2 The slag and impurities are enriched in the slag ball after the wax mold casting and shell cleaning of the present invention;

[0040] Figure 3 This is an X-ray flaw detection image of the casting body of the product after pouring of the present invention.

[0041] 1. Sprue; 2. Horizontal runner; 3. Ingate; 4. Exhaust device; 5. Slag ball; 6. Casting wax mold. DETAILED DESCRIPTION

[0042] In order to make the technical means, objectives and effects of the present invention easier to understand, embodiments of the present invention are described in detail below with reference to specific figures.

[0043] It should be noted that all directional and positional terms in the present invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inside," "outside," "top," "low," "lateral," "longitudinal," and "center," are used only to explain the relative positional relationships and connections between components in a specific state. They are intended solely to facilitate the description of the present invention and do not require that the present invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, terms such as "first" and "second" in the present invention are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly indicating the number of the technical features indicated.

[0044] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical connections; direct connections or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0045] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0046] like Figure 1-3 As shown, one purpose of the present invention is to disclose a wax mold tree structure for investment precision casting of a titanium alloy joint, comprising a sprue 1, a runner 2, an ingrate 3, an exhaust device 4 and a slag collecting ball 5;

[0047] The sprue 1 is arranged along the length direction of the casting wax mold 6, and one end of the sprue 1 is connected to the runner 2. The sprue 1 is used to guide the titanium alloy liquid from the ladle to flow smoothly into the runner 2 and the ingrate 3;

[0048] The runner 2 is arranged in a direction perpendicular to the sprue 1 and is used to evenly distribute the titanium alloy liquid flowing from the sprue 1 to each ingrown 3;

[0049] The ingrowth 3 is arranged parallel to the sprue 1, and at least two ingrowths 3 are provided. One end of the ingrowth 3 is connected to the end of the runner 2 away from the sprue 1, and the end of the ingrowth 3 away from the runner 2 is connected to the casting wax mold 6. The ingrowth 3 is used to guide the titanium alloy liquid from the runner 2 to the casting wax mold 6 and control the flow state of the titanium alloy liquid;

[0050] The exhaust device 4 is arranged at the top of the casting wax mold 6 and is used for exhausting and removing slag at a high superheat during the pouring process;

[0051] The slag collecting balls 5 are arranged at the bottom of the casting wax mold 6 for settling and collecting impurities.

[0052] The sprue 1 guides the titanium alloy liquid to flow smoothly from the ladle into the runner 2, ensuring that the titanium alloy liquid has sufficient flow rate and flow rate, while controlling the flow stability and reducing turbulence. The runner 2 evenly distributes the titanium alloy liquid flowing from the sprue 1 to each entendre 3, ensuring that the titanium alloy liquid can smoothly and evenly fill each part of the casting and maintain the fluid dynamics balance of the entire casting system. The entendre 3 is designed with an inclination angle of 15-25° to inject the titanium alloy liquid along the tangential direction of the cavity wall, reducing turbulence and bubble formation. The entendre 3 guides the titanium alloy liquid from the runner 2 to the wax mold and controls its flow state to ensure that the casting is evenly filled and prevent defects such as shrinkage cavities and shrinkage. The exhaust device 4 is arranged at the top of the wax mold to discharge gas and slag at a high superheat during the pouring process, further reducing the probability of internal defects in the casting and improving the quality of the casting. The slag ball 5 is located at the bottom of the wax mold and is specifically used for impurity sedimentation and collection to prevent impurities from entering the main body of the casting, significantly reducing the slag inclusion rate, and improving the purity and mechanical properties of the casting.

[0053] This setting is not a simple combination of various parts, but through the collaborative design of "equal-section runner + bottom slag ball + top exhaust needle", it solves the problems of titanium liquid flow control and impurity removal in titanium alloy joint casting, so that impurities can be effectively collected during the casting process instead of being dispersed throughout the casting, thereby greatly reducing the slag inclusion rate of the casting and improving the quality and reliability of the casting. It not only ensures short filling time and good shrinkage compensation effect, but also solves the problem of impurity dispersion.

[0054] Specifically, the sprue 1 , the runner 2 , and the ingrate 3 are topologically designed, and the three use a “1-1-N” topological layout, where N ≥ 4.

[0055] The "1-1-N" topological layout ensures that the titanium alloy liquid can quickly and smoothly fill all parts of the casting. It is suitable for complex structures or slender pipeline castings. It optimizes fluid dynamics and reduces the possibility of turbulence and inclusion formation, thereby reducing the incidence of common casting defects such as shrinkage cavities and shrinkage, improving the overall quality and reliability of the casting, and helping to avoid local material shortages or insufficient filling. In addition, the efficient pouring system design reduces the scrap rate and the need for manual trimming. For example, traditional technology requires 0.35 hours of labor time per piece, while the patented technology achieves 0 hours of labor time for trimming, improving the degree of production automation and overall efficiency.

[0056] This setting optimizes the flow path and speed of the titanium alloy liquid, effectively controls various potential problems in the casting process, and greatly improves the quality of castings and production efficiency.

[0057] Specifically, the cross section of sprue 1 S1 = cross section of runner 2 S2 = ∑ cross section of ingrate 3 S3. A ±5% tolerance is allowed between S1, S2 and S3, which can be verified by the formula: S1 = πD 2 / 4=W×H=n×πd 2 / 4;

[0058] Where: D is the diameter of sprue 1;

[0059] W×H is the width × height of the runner;

[0060] n is the number of ingates 3;

[0061] d is the diameter of single ingrate 3.

[0062] By matching the cross-sectional areas of the sprue 1, runner 2 and all ingates 3, it is possible to ensure that the flow of the titanium alloy liquid in the entire casting system is smooth and continuous, avoiding turbulence and uneven filling caused by local excessive speed or slowness. Precise control of the cross-sectional area of ​​each part helps to achieve uniform distribution of the titanium alloy liquid, ensuring that all areas of the casting are fully filled. Balanced fluid dynamics conditions reduce the probability of formation of bubbles and oxide inclusions, thereby reducing the risk of internal defects such as shrinkage cavities and shrinkage.

[0063] This setting enables the titanium alloy liquid to flow into the casting in an optimized state by accurately calculating and matching the cross-sectional area of ​​each runner, thus ensuring the integrity and surface quality of the casting, reducing the occurrence of casting defects, and ensuring the predictability and repeatability of the titanium alloy liquid flow state during each casting process, significantly reducing the scrap rate and improving production efficiency.

[0064] Specifically, the sprue 1 is a column with a diameter of Φ30-50 mm.

[0065] The sprue 1 is the main channel for the titanium alloy liquid to enter the casting from the outside. Its main function is to guide the titanium alloy liquid to flow smoothly from the ladle into the cross runner 2 and the ingrowth 3, and finally reach the casting cavity. The appropriate diameter can ensure that the titanium alloy liquid has sufficient flow rate and flow to ensure the smooth progress of the filling process, help control the flow state of the titanium alloy liquid, and reduce the occurrence of turbulence. It is suitable for titanium alloy, which has poor fluidity, a melt viscosity of about 10 to 20 times that of steel, and is easy to react with gases such as oxygen and nitrogen to form inclusions. It helps to reduce defects such as shrinkage cavities and shrinkage that may appear inside the casting.

[0066] The diameter range of Φ30-50mm can provide sufficient cross-sectional area to ensure the smoothness of titanium alloy liquid, but not be too large to cause unnecessary heat loss or too small to increase flow resistance, thereby improving the quality and efficiency of filling, reducing the turbulence and oxidation risks formed by titanium alloy liquid during the flow process, and thus reducing the possibility of inclusion formation.

[0067] Specifically, the length of the runner 2 is L=N×l, where l=1.2-1.5 times the shortest projection length of the joint.

[0068] By accurately calculating the length of runner 2 (L = N × l), it can be adjusted according to the actual needs of the casting, ensuring that the titanium alloy liquid can smoothly and evenly fill each ingrown 3 and, in turn, reach all parts of the casting. This helps avoid localized material shortages or uneven filling, and improves the overall quality and consistency of the casting. The standardized runner 2 length design makes the flow state of the titanium alloy liquid more predictable and controllable during each casting process, improving the stability and repeatability of the process, significantly reducing scrap rates, and improving production efficiency.

[0069] This setting can effectively achieve uniform distribution of titanium alloy liquid, optimize the fluid dynamics performance of the entire pouring system, and improve the quality of castings and production stability.

[0070] Specifically, the ingrowth channel 3 is set at an inclination angle of 15-25 degrees, so that the titanium alloy liquid is injected along the tangent direction of the cavity wall to reduce turbulence.

[0071] The tilt angle design allows the titanium alloy liquid to enter the casting in a tangential direction along the cavity wall, which helps reduce the direct impact of the titanium alloy liquid on the cavity wall or the previously injected titanium alloy liquid, thereby reducing the occurrence of turbulence. The tangential injection method can effectively reduce the chance of the titanium alloy liquid coming into contact with the air and reduce the risk of bubble formation. At the same time, since the violent disturbance of the titanium alloy liquid is reduced, the probability of oxide inclusion formation is also reduced. By controlling the inflow angle of the titanium alloy liquid, the titanium alloy liquid can fill the entire cavity more smoothly, ensuring that all parts of the casting are evenly and fully filled, avoiding the problem of local material shortage or insufficient filling.

[0072] This setting can effectively reduce turbulence, the formation of bubbles and oxide inclusions, and significantly improve the quality of castings and production efficiency.

[0073] Specifically, at least two exhaust devices 4 are provided, and the exhaust devices 4 are round rods.

[0074] By setting up at least two exhaust devices 4, different areas of the casting can be covered more effectively, ensuring that the gas in the entire pouring process can be fully discharged, and promoting the discharge of impurities such as slag. Reasonable arrangement of the exhaust device 4 can guide the titanium alloy liquid to flow more smoothly into the mold cavity, reduce turbulence, and thus improve the overall quality and surface finish of the casting.

[0075] This setting can significantly improve the exhaust and slag removal effects, reduce internal defects of castings, and increase the stability and reliability of the casting process. It is simple and practical in design and easy to manufacture and install.

[0076] Preferably, 2-4 exhaust devices 4 are provided, and the exhaust devices 4 are round rods with a diameter of Φ3 mm, a height of 30-50 mm, and a slope of 1-1.5°.

[0077] The installation of two to four exhaust devices (4) provides comprehensive coverage across different areas of the casting, ensuring that gas and slag generated during the pouring process are effectively exhausted, helping to reduce defects such as porosity and inclusions. A 1-1.5° slope allows gas and slag to rise and be exhausted more easily with the titanium alloy liquid. The design of the exhaust devices (4) helps guide the titanium alloy liquid into the mold cavity smoothly, avoiding turbulence and impact, thereby improving filling quality. The round rod, with a diameter of Φ3 mm and a height of 30-50 mm, is simple, practical, and easy to manufacture and install.

[0078] This setting significantly improves the exhaust and slag removal effects, reduces internal defects in castings, and increases the stability and reliability of the casting process, making it easier for actual production and maintenance.

[0079] Specifically, the diameter of the slag ball 5 is D'=Φ20~30mm, the neck diameter is d'=Φ10~15mm, and the neck height is h'=0.8~1.5d'.

[0080] The main function of the slag ball 5 is to serve as a sedimentation area for impurities, so that inclusions, oxides, etc. generated during the pouring process can be gathered here to prevent them from entering the main body of the casting. Through reasonable size design, such as the ball diameter D'=Φ20~30mm, sufficient space is ensured to accommodate these impurities. The neck diameter d'=Φ10~15mm and the neck height h'=0.8~1.5d' help guide the titanium alloy liquid to flow smoothly into and out of the slag ball 5, reducing turbulence and bubble formation. At the same time, the neck structure also makes it easy to cut the slag ball 5 from the casting in subsequent processing without affecting the quality of the casting body. The slag ball 5 is set at the bottom end face of the casting wax mold 6, away from the key parts of the casting. This can effectively prevent impurities from entering important functional areas of the casting, such as flanges and double-pronged heads, which have strict requirements on mechanical properties, geometric accuracy and surface quality.

[0081] Experimental data shows that after using slag collecting balls 5, the slag inclusion size of castings is reduced from 0.5-3mm with traditional technology to ≤0.1mm, and the slag inclusion rate is reduced from 3.2-4.5% to ≤0.8%, with a slag collection efficiency of up to 99.5%. This greatly improves the internal quality and surface finish of the castings. Due to the reduction of inclusions, the mechanical properties of the castings, such as tensile strength, have been significantly improved. For example, the probability of slag enrichment in joint products is greatly reduced, which directly improves the bearing capacity and reduces the problem of mechanical property degradation caused by inclusions. In addition, it facilitates subsequent processing and eliminates the need for additional manual finishing and cleaning work. Traditional technology requires 0.35 hours of labor time per piece, while 0 hours of labor time for finishing is achieved, greatly improving production efficiency.

[0082] This setting effectively solves the problem of impurity removal in titanium alloy joint casting and significantly improves the quality and reliability of castings.

[0083] Specifically, the exhaust device 4 and the slag collecting ball 5 are made of the same wax as the sprue wax, and the exhaust device 4 and the slag collecting ball 5 are respectively connected to the casting wax mold 6 by welding.

[0084] Using the same material as the sprue wax ensures that the exhaust device 4 and the slag ball 5 have similar thermophysical properties to the entire wax pattern system, helping to maintain consistent behavior throughout the dewaxing process and avoiding deformation or cracking caused by material differences. The exhaust device 4 and the slag ball 5 are fixed to specific positions on the casting wax pattern 6 by adhesive wax, ensuring that they will not shift during subsequent steps such as impregnation with refractory slurry and sanding, thereby ensuring the precise formation of the final casting. During the high-temperature dewaxing process, since the exhaust device 4 and the slag ball 5 are made of the same fusible material, they can completely melt and flow out of the shell mold without leaving any residue, ensuring the cleanliness and integrity of the casting cavity.

[0085] This setup reduces the risk of internal defects in castings, such as pores and inclusions, improves the overall quality and surface finish of castings, simplifies the production process, eliminates the need for additional preparation of components made of different materials, and reduces production costs and complexity. At the same time, the standardized design also facilitates operation and maintenance.

[0086] Preferably, the sprue wax is K512 model wax.

[0087] K512 type wax has good plasticity and stability, which can ensure high precision when making complex-shaped runners, exhaust devices 4 and slag collecting balls 5, helping to ensure the geometric accuracy of the entire casting system, thereby improving the quality of the final casting. In addition, K512 type wax has a low melting point and good fluidity. During the high-temperature dewaxing process, it can completely melt and flow out of the shell mold without leaving any residue, ensuring the cleanliness of the casting cavity and reducing casting defects caused by residues. Using the same type of wax material to make the runner, exhaust device 4 and slag collecting balls 5 ensures that these components behave consistently throughout the dewaxing process, avoiding deformation or cracking problems caused by differences in the thermophysical properties of different materials.

[0088] This setting reduces production and management costs, enhances process stability and repeatability, and produces fewer volatiles during the dewaxing process, which is beneficial to protecting the working environment and employee health.

[0089] Another object of the present invention is to disclose a method for manufacturing a wax pattern tree for investment casting of a titanium alloy joint, based on the above-mentioned wax pattern tree structure, specifically comprising the following steps:

[0090] S1: Design and preparation; design the positions and dimensions of the sprue 1, runner 2, ingates 3, exhaust device 4, slag collecting balls 5, and casting wax pattern 6 according to the specific requirements of the casting;

[0091] Ensure that the size and position of each component meet process requirements to optimize the flow path of the titanium alloy liquid and reduce turbulence and inclusions. This setting reduces casting defects such as porosity and shrinkage through reasonable design, improving the overall quality and reliability of the casting.

[0092] S2: Making wax model components: Use a wax injection machine to inject K512 model wax into the mold to form a wax model of the desired shape;

[0093] K512 wax offers excellent plasticity and stability, ensuring high-precision molding of complex-shaped components. Using a single wax material simplifies the production process, reducing cost and complexity. Furthermore, K512 wax is environmentally friendly, producing fewer volatiles during the dewaxing process, which is beneficial for protecting the environment and worker health.

[0094] S3: Assembling the wax model tree: Fix the prepared sprue 1, runner 2, ingates 3, exhaust device 4 and slag collecting balls 5 on the casting wax model 6 by bonding wax to form a complete wax model tree structure;

[0095] All components use the same type of wax material to ensure consistent behavior throughout the dewaxing process, avoiding deformation or cracking. K512 wax completely melts and flows out of the shell mold at high temperature without leaving any residue, ensuring the cleanliness of the casting cavity. The standardized design facilitates operation and maintenance, improving work efficiency.

[0096] Through the collaborative design of "equal-section runner + bottom slag collecting ball + top exhaust needle", the problems of titanium liquid flow control and impurity removal in titanium alloy joint casting are solved, and the quality of castings and production efficiency are improved. The slag collecting ball 5 can effectively collect impurities and prevent them from entering the main body of the casting, significantly reducing the slag inclusion rate and improving the purity and mechanical properties of the casting.

[0097] This setting optimizes the flow path and speed of the titanium alloy liquid, effectively controls various potential problems in the casting process, and greatly improves the quality of castings and production efficiency. At the same time, by using a uniform model of wax material, it simplifies the production process and enhances the stability and repeatability of the process.

[0098] After the wax pattern is completed, it can be used for investment casting. The specific steps are as follows:

[0099] S4: Shell making: The assembled wax model tree is immersed in refractory material slurry multiple times and sprinkled with refractory sand to gradually form a solid shell. The shell mold is allowed to harden and fully dry under specific conditions to ensure that it is strong enough to withstand the subsequent high-temperature dewaxing process;

[0100] S5: Dewaxing and calcining: The hardened shell mold is placed in a furnace and heated to completely melt the wax mold and flow out, leaving a cavity as a space for the titanium alloy liquid to be filled. The temperature is further increased to calcine the shell mold to enhance its structural strength and prepare it to receive the titanium alloy liquid pouring;

[0101] S6: Pouring and cooling: The molten titanium alloy liquid flows into the casting cavity through the sprue 1, runner 2, and ingates 3 according to the designed path. The exhaust device 4 helps to exhaust the gas, and the slag ball 5 collects impurities. After the titanium alloy liquid is completely filled and solidified, the shell mold is carefully removed and the casting is taken out;

[0102] S7: Post-processing: Clean the casting, remove the residual shell mold material on the surface, and check whether the casting quality meets the design standards.

[0103] Example 1

[0104] For example, a TC4 titanium alloy joint for aerospace castings was put into production. 120 pieces were produced. The shortest projection length of a single joint was 90 mm, and the wall thickness was 18 mm. Sprue 1 was Φ45 mm, runner 2 had a cross-sectional dimension of 45 × 35 mm, and four ingates were used, with a single ingate measuring Φ25 mm. Table 1 summarizes the technical specifications of the joint casting (average per piece).

[0105] Table 1. Technical index statistics of joint castings

[0106]

[0107] As shown in Table 1, the slag inclusion size of the castings was reduced from 0.5-3mm in traditional technology to ≤0.1mm, and the slag inclusion rate was reduced from 3.2-4.5% to ≤0.8%. The slag collection efficiency reached 99.5%, greatly improving the internal quality and surface finish of the castings. No additional manual finishing and cleaning work was required for the castings (the original finishing labor time was 0.35h), achieving 0 hours of finishing labor time. This greatly improved production efficiency, reduced scrap rate and production costs, and no slag inclusion defects were detected in the castings of batch products using X-ray imaging.

[0108] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wax pattern tree structure for investment casting of titanium alloy joints, characterized in that: It includes a sprue (1), a runner (2), an inner runner (3), an exhaust device (4) and a slag collecting ball (5). The sprue (1) is arranged along the length direction of the casting wax mold (6), one end of the sprue (1) is connected to the runner (2), and the sprue (1) is used to guide the titanium alloy liquid to flow smoothly from the ladle into the runner (2) and the ingrown (3); The runner (2) is arranged in a direction perpendicular to the sprue (1) and is used to evenly distribute the titanium alloy liquid flowing from the sprue (1) to each of the ingrowns (3); The ingrowth (3) is arranged in parallel with the sprue (1), and at least two ingrowths (3) are provided. One end of the ingrowth (3) is connected to the end of the runner (2) away from the sprue (1), and the end of the ingrowth (3) away from the runner (2) is connected to the casting wax mold (6). The ingrowth (3) is used to guide the titanium alloy liquid from the runner (2) to the casting wax mold (6) and control the flow state of the titanium alloy liquid. The exhaust device (4) is arranged at the top of the casting wax mold (6) and is used for exhausting and slag removal at a high superheat during the pouring process; The slag collecting ball (5) is arranged at the bottom of the casting wax mold (6) and is used for settling and collecting impurities; The cross section S1 of the sprue (1) = the cross section S2 of the runner (2) = ∑ the cross section S3 of the ingrown runner (3), and a ±5% tolerance is allowed between S1, S2 and S3, which is verified by the formula: S1 = πD 2 / 4=W×H=n×πd 2 / 4; Wherein: D is the diameter of the sprue (1); W×H is the width×height of the runner (2); n is the number of the ingates (3); d is the diameter of the inner runner (3).

2. The wax pattern tree structure for investment casting of titanium alloy joint according to claim 1, characterized in that: The sprue (1), the runner (2) and the ingrown (3) are designed in a topological manner, and the three use a "1-1-N" topological layout, where N is greater than or equal to 4.

3. The wax pattern tree structure for investment casting of titanium alloy joint according to claim 1, characterized in that: The sprue (1) is a column with a diameter of Φ30-50 mm.

4. The wax pattern tree structure for investment casting of titanium alloy joint according to claim 1, characterized in that: The length of the runner (2) is L=N×l, where l=1.2-1.5 times the shortest projection length of the joint.

5. The wax pattern tree structure for investment casting of titanium alloy joint according to claim 1, characterized in that: The ingrown channel (3) is set at an inclination angle of 15-25 degrees, so that the titanium alloy liquid is injected along the tangent direction of the cavity wall to reduce turbulence.

6. The wax pattern tree structure for investment casting of titanium alloy joint according to claim 1, characterized in that: The exhaust devices (4) are provided in 2-4 pieces, and are round rods with a diameter of Φ3 mm, a height of 30-50 mm, and a slope of 1-1.5°.

7. The wax pattern tree structure for investment casting of titanium alloy joint according to claim 1, characterized in that: The slag collecting ball (5) has a ball diameter D'=Φ20~30mm, a neck diameter d'=Φ10~15mm, and a neck height h'=0.8~1.5d'.

8. The wax pattern tree structure for investment casting of titanium alloy joint according to claim 1, characterized in that: The exhaust device (4) and the slag collecting ball (5) are made of the same wax as the sprue wax, and the exhaust device (4) and the slag collecting ball (5) are respectively connected to the casting wax mold (6) by group welding.

9. A method for manufacturing a wax pattern tree for investment casting of a titanium alloy joint, characterized in that: The wax pattern tree structure for manufacturing the titanium alloy joint investment casting according to any one of claims 1 to 8 specifically comprises the following steps: S1: Design and preparation: Design the positions and sizes of the sprue (1), the runner (2), the ingrown runner (3), the exhaust device (4), the slag collecting ball (5) and the casting wax mold (6) according to the specific requirements of the casting; S2: Making wax model components: using a wax injection machine to inject wax into the mold to form a wax model of the desired shape; S3: Assembling the wax model tree: fixing the prepared sprue (1), the runner (2), the ingrown runner (3), the exhaust device (4) and the slag collecting ball (5) on the casting wax model (6) to form a complete wax model tree structure.

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