Wax pattern tree structure for precision investment casting of titanium alloy joint and manufacturing method of wax pattern tree structure

Abstract

The invention relates to the technical field of titanium alloy investment casting processes, in particular to a wax mold tree structure for titanium alloy joint investment precision casting and a manufacturing method thereof.The wax mold tree structure is characterized in that a sprue is arranged in the length direction of a casting wax mold, one end of the sprue is connected with a runner, the runner is arranged in the direction perpendicular to the sprue, and an ingate is parallel to the sprue; one end of the ingate is connected with one end, far away from the sprue, of the cross gate, the end, far away from the cross gate, of the ingate is connected with the casting wax mold, the exhaust device is arranged at the top end of the casting wax mold, and the slag collecting ball is arranged at the bottom of the casting wax mold. Through the design of the slag collecting ball at the bottom, impurities and slag can be effectively settled and collected in the slag collecting ball and are prevented from entering a casting main body, so that the slag inclusion size of the casting is reduced to be less than or equal to 0.1 mm from 0.5-3 mm in the prior art, the slag inclusion rate is reduced to be less than or equal to 0.8% from 3.2-4.5%, the slag collecting efficiency is as high as 99.5%, and the internal quality and the surface smoothness of the casting are greatly improved.

Description

Technical Field

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

[0002] Due to its characteristics such as low density, high specific strength, high temperature resistance, and corrosion resistance, titanium alloys are widely used in modern industrial fields such as aerospace. Investment precision casting technology is one of the key technologies for manufacturing complex-shaped titanium alloy components. However, it has a high melting point (1660 - 1800 °C), poor fluidity (the melt viscosity is about 10 - 20 times that of steel), and is prone to react with gases such as oxygen and nitrogen to form inclusions, resulting in a relatively high casting defect rate.

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

[0004] In investment casting of titanium alloys, traditional bottom gating systems are prone to casting defects such as shrinkage cavities and porosity. Although the top gating system has a short filling time and good feeding effect, it has problems such as intensified turbulence and impurity dispersion. The probability of slag enrichment in joint products is as high as 25 - 45%, which directly affects the load-bearing performance (such as a 15 - 20% decrease in tensile strength), severely limits the quality and reliability of titanium alloy castings, and increases production costs and scrap rates.

[0005] Publication No.: CN115319026B, an investment counter-gravity casting shell air exhaust and filling method for aluminum alloys, includes: Step S1, using a mold to press an exhaust runner with stepped air exhaust;

[0006] Step S2, pasting the exhaust runner above the casting wax pattern of the casting after preparing the gating system; Step S3, making a mold shell for the casting wax pattern with the exhaust runner and dewaxing it. The casting cavity in the mold shell corresponds to the casting wax pattern before dewaxing, and the exhaust channel in the mold shell corresponds to the exhaust runner before dewaxing. However, this solution uses a top air exhaust and bottom metal liquid injection structure, and there are 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 titanium alloy joint casting. Summary of the Invention

[0008] In view of this, the present invention aims to provide 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 difficult control of titanium liquid flow and difficult removal of impurities in the casting of titanium alloy joints.

[0009] Aiming at the problems such as easy generation of shrinkage cavities and porosity in the traditional bottom gating system, as well as the disadvantages of increased turbulence and impurity dispersion in the top gating system, the present invention proposes an innovative solution. Through the collaborative design of "constant cross-section runner + bottom slag collecting ball + top exhaust needle", the problems of titanium liquid flow control and impurity removal in the casting of titanium alloy joints are solved, the quality and production efficiency of the casting are improved. The slag collecting ball 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. In this way, both the short filling time and good feeding effect are ensured, and the problem of impurity dispersion is solved.

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

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

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

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

[0014] The ingate is arranged parallel to the sprue. At least two ingates are provided. One end of the ingate is connected to the end of the runner far from the sprue, and the end of the ingate far from the runner is connected to the casting wax pattern. The ingate is used to guide the titanium alloy liquid from the runner to the casting wax pattern and control the flow state of the titanium alloy liquid;

[0015] The exhaust device is arranged at the top end of the casting wax pattern, and is used for exhausting and slag discharging at a relatively high superheat temperature during the pouring process;

[0016] The slag collecting ball is arranged at the bottom of the casting wax pattern, and is used for impurity sedimentation and collection.

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

[0018] Furthermore, the cross-sectional area S1 of the sprue = the cross-sectional area S2 of the runner = ∑ the cross-sectional areas S3 of the ingates, and it 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 a single ingate.

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

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

[0025] Furthermore, the ingate is provided with an inclination angle of 15 - 25°, so that the titanium alloy liquid is injected along the tangential direction of the cavity wall to reduce turbulence.

[0026] Furthermore, 2 - 4 exhaust devices are provided. The exhaust device is a round bar with a diameter of Φ3 mm and a height of 30 - 50 mm, and the slope is 1 - 1.5°.

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

[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 pattern through 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 the wax pattern tree structure for investment casting of any of the above - mentioned titanium alloy joints, and specifically includes the following steps:

[0030] S1: Design and preparation: Design the positions and dimensions of the sprue, the runner, the ingate, the exhaust device, the slag collecting ball and the casting wax pattern according to the specific requirements of the casting;

[0031] S2: Making wax pattern components: Use a wax injection machine to inject wax material into the mold to form a wax pattern with the required shape;

[0032] S3: Assembling the wax pattern tree: Fix the made sprue, runner, ingate, exhaust device and slag collecting ball on the casting wax pattern to form a complete wax pattern tree structure.

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

[0034] 1. Through the design of the bottom slag collecting ball in the present invention, impurities and dross can effectively settle and be collected in the slag collecting ball, avoiding entering the main body of the casting. As a result, the slag inclusion size of the casting is reduced from 0.5 - 3 mm in the traditional technology to ≤0.1 mm, 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%. This greatly improves the internal quality and surface finish of the casting.

[0035] 2. By adopting the topological design of "equal cross-section runner + single sprue - single cross runner and multiple ingates" and setting the ingates at a specific inclination angle in the present invention, it helps the titanium liquid to be smoothly injected along the tangential direction of the cavity wall, reducing the turbulent flow phenomenon and ensuring the stable flow and rapid filling of the melt. In addition, the design of the top exhaust needle further enhances the exhaust and slag removal effect during the pouring process, reducing the occurrence probability of casting defects.

[0036] 3. The present invention effectively isolates impurities through the slag collecting ball, eliminating the need for additional manual trimming and cleaning work on the casting. The manual trimming time is reduced to 0 hours, greatly improving production efficiency, reducing the scrap rate and production cost, and being particularly suitable for large-scale industrial production requirements. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0039] Figure 2 is a diagram showing the enrichment of slag and impurities in the slag collecting ball after the wax pattern is poured and the shell is removed in the present invention;

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

[0041] 1. Sprue; 2. Cross runner; 3. Ingate; 4. Exhaust device; 5. Slag collecting ball; 6. Casting wax pattern. DETAILED DESCRIPTION OF THE INVENTION

[0042] In order to make the technical means, achieved purpose and effects of the present invention easy to understand, the embodiments of the present invention will be described in detail below with reference to specific drawings.

[0043] It should be noted that all the terms indicating directionality and position in the present invention, such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "inner", "outer", "top", "bottom", "lateral", "longitudinal", "center", etc., are only used to explain the relative positional relationship and connection situation between components in a specific state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features.

[0044] In the description of the present invention, unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0046] As Figures 1-3 shown, an object of the present invention is to disclose a wax pattern tree structure for precision investment casting of titanium alloy joints, including a sprue 1, a runner 2, ingates 3, an exhaust device 4, and a slag trap ball 5;

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

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

[0049] The ingate 3 is arranged in parallel with the sprue 1. At least two ingates 3 are provided. One end of the ingate 3 is connected to one end of the runner 2 away from the sprue 1, and the end of the ingate 3 away from the runner 2 is connected to the casting wax pattern 6. The ingate 3 is used to guide the titanium alloy liquid from the runner 2 to the casting wax pattern 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 pattern 6 and is used for exhausting gas and slag during pouring at a relatively high superheat degree.

[0051] The slag collecting ball 5 is arranged at the bottom of the casting wax pattern 6 and is used for impurity sedimentation and collection.

[0052] The sprue 1 guides the titanium alloy liquid to smoothly flow from the ladle into the runner 2, ensuring that the titanium alloy liquid has sufficient flow rate and flow volume. At the same time, it controls the flow stability, reduces the turbulent flow phenomenon. The runner 2 evenly distributes the titanium alloy liquid flowing in from the sprue 1 into each ingate 3, ensuring that the titanium alloy liquid can fill each part of the casting smoothly and evenly, maintaining the hydrodynamic balance of the entire gating system. The ingate 3 is designed with an inclination angle of 15 - 25°, so that the titanium alloy liquid is injected along the tangential direction of the cavity wall, reducing the formation of turbulent flow and bubbles. The ingate 3 guides the titanium alloy liquid from the runner 2 to the wax pattern and controls its flow state, ensuring uniform filling of the casting, preventing defects such as shrinkage cavities and shrinkage porosity. The exhaust device 4 is arranged at the top of the wax pattern and is used for exhausting gas and slag at a relatively high superheat degree during pouring, further reducing the occurrence probability of internal defects of the casting and improving the casting quality. The slag collecting ball 5 is located at the bottom of the wax pattern and is specifically used for impurity sedimentation and collection, avoiding 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 simply a combination of each part, but through the collaborative design of "equal cross-section gating + bottom slag collecting ball + top exhaust needle", it solves the problems of titanium liquid flow control and impurity removal in the casting of titanium alloy joints, enabling impurities to be effectively collected during the casting process instead of being dispersed throughout the casting, thereby greatly reducing the slag inclusion rate of the casting, improving the casting quality and reliability. It not only ensures a short filling time and good feeding effect, but also solves the problem of impurity dispersion.

[0054] Specifically, the sprue 1, the runner 2, and the ingate 3 adopt topological design, 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 castings with complex structures or slender pipelines. 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 problems such as 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 per piece, while the patented technology achieves 0 hours of labor time for trimming, improving the degree of automation and overall efficiency of production.

[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 entrapment 3 S3, and 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 ingates 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. Accurate 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 accurately calculates and matches the cross-sectional area of each runner so that the titanium alloy liquid can flow into the casting in the most optimized state, ensuring the integrity and surface quality of the casting, reducing the occurrence of casting defects, and ensuring the predictability and repeatability of the flow state of the titanium alloy liquid 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 serves as the main channel for the titanium alloy liquid to enter the mold from the outside. Its main function is to guide the titanium alloy liquid from the ladle smoothly into the runner 2 and the ingate 3, and finally reach the cavity of the casting. A suitable diameter can ensure that the titanium alloy liquid has sufficient flow velocity and flow rate to ensure the smooth progress of the filling process, help control the flow state of the titanium alloy liquid, reduce the occurrence of turbulent flow phenomena, and is suitable for materials like titanium alloy with poor fluidity, a melt viscosity about 10 - 20 times that of steel, and is prone to react with gases such as oxygen and nitrogen to form inclusions. It helps reduce defects such as shrinkage cavities and porosity that may appear inside the casting.

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

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

[0068] By precisely calculating the length L of the runner 2 = N×l, the length of the runner 2 can be adjusted according to the actual needs of the casting to ensure that the titanium alloy liquid can fill each ingate 3 smoothly and evenly, and then reach all parts of the casting, which helps avoid problems such as local material shortage or uneven filling, improving the overall quality and consistency of the casting. The standardized design of the length of the runner 2 makes the flow state of the titanium alloy liquid more predictable and controllable during each casting process, enhances the stability and repeatability of the process, significantly reduces the scrap rate and improves production efficiency.

[0069] This setting can effectively achieve the uniform distribution of the titanium alloy liquid, optimize the hydrodynamic performance of the entire gating system, and improve the quality of the casting and the stability of production.

[0070] Specifically, the ingate 3 is set with an inclination angle of 15 - 25°, so that the titanium alloy liquid is injected along the tangential direction of the cavity wall to reduce turbulent flow.

[0071] The inclination angle design enables the titanium alloy liquid to enter the casting interior along the tangential direction of 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, thus reducing the occurrence of turbulent flow. The tangential injection method can effectively reduce the chance of contact between the titanium alloy liquid and air, reducing the risk of bubble formation. At the same time, due to the reduction of the violent disturbance of the titanium alloy liquid, the formation probability of oxide inclusions 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 can be filled evenly and sufficiently, and avoiding problems such as local material shortage or insufficient filling.

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

[0073] Specifically, at least two exhaust devices 4 are provided, and the exhaust device 4 is a round bar.

[0074] By providing at least two exhaust devices 4, different areas of the casting can be covered more effectively, ensuring that the gas during the entire pouring process can be fully discharged. It can also promote the discharge of impurities such as slag. The reasonably arranged exhaust device 4 can guide the titanium alloy liquid to flow into the cavity more smoothly, reducing the turbulence phenomenon, thereby improving the overall quality and surface finish of the casting.

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

[0076] Preferably, 2 - 4 exhaust devices 4 are provided. The exhaust device 4 is a round bar with a diameter of Φ3mm and a height of 30 - 50mm, and a slope of 1 - 1.5°.

[0077] Providing 2 - 4 exhaust devices 4 can cover different areas of the casting more comprehensively, ensuring that the gas and slag generated during the pouring process can be effectively discharged, helping to reduce defects such as pores and inclusions. The slope design of 1 - 1.5° makes it easier for the gas and slag to rise with the titanium alloy liquid and be discharged. The design of the exhaust device 4 helps to guide the titanium alloy liquid to flow smoothly into the cavity, avoiding turbulence and impact, thereby improving the filling quality. The round bar design with a diameter of Φ3mm and a height of 30 - 50mm is simple and practical, and is easy to manufacture and install.

[0078] This setting significantly improves the exhaust and slag discharge effects, reduces internal defects of the casting, and also increases the stability and reliability of the casting process, facilitating actual production and maintenance.

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

[0080] The main function of the slag collecting ball 5 is to serve as a sedimentation area for impurities, enabling inclusions, oxides, etc. generated during the pouring process to accumulate here and preventing them from entering the main body of the casting. Through reasonable size design, such as a ball diameter D’ = Φ20 - 30 mm, sufficient space is ensured to accommodate these impurities. The neck diameter d’ = Φ10 - 15 mm, and the neck height h’ = 0.8 - 1.5d’ helps to guide the titanium alloy liquid to flow smoothly into and out of the slag collecting ball 5, reducing turbulence and bubble formation. At the same time, the neck structure also facilitates cutting the slag collecting ball 5 from the casting during subsequent processing without affecting the quality of the casting body. The slag collecting ball 5 is arranged at the bottom end face of the casting wax mold 6, far from the key parts of the casting, which can effectively prevent impurities from entering the important functional areas of the casting, such as flanges and double fork heads, where strict requirements are imposed on mechanical properties, geometric accuracy, and surface quality.

[0081] Experimental data shows that after using the slag collecting ball 5, the slag inclusion size in the casting has decreased from 0.5 - 3 mm in the traditional technology to ≤0.1 mm, and the slag inclusion rate has dropped from 3.2 - 4.5% to ≤0.8%, with a slag collection efficiency as high as 99.5%. This has greatly improved the internal quality and surface finish of the casting. Due to the reduction in the presence of inclusions, the mechanical properties such as the tensile strength of the casting have been significantly improved. For example, the probability of slag inclusion enrichment in the joint product has been greatly reduced, directly enhancing the load-bearing performance and reducing the problem of mechanical property degradation caused by inclusions. In addition, it is convenient for subsequent processing, eliminating the need for additional manual trimming and cleaning work. The traditional technology required 0.35 hours / piece of manual labor time, achieving 0 hours of trimming manual labor time, thus greatly improving the production efficiency.

[0082] This setting effectively solves the problem of impurity removal in the casting of titanium alloy joints, significantly improving the quality and reliability of the casting.

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

[0084] Using the same material as the runner wax ensures that the exhaust device 4 and the slag collecting ball 5 have similar thermophysical properties to the entire wax mold system, which helps to maintain consistent behavior during the entire dewaxing process and avoid deformation or cracking problems caused by material differences. The exhaust device 4 and the slag collecting ball 5 are fixed at specific positions on the casting wax mold 6 through adhesive wax to ensure that they will not shift during subsequent steps such as impregnating refractory material slurries and sanding, thus ensuring the precise forming of the final casting. During the dewaxing process at high temperatures, since the exhaust device 4 and the slag collecting ball 5 use the same fusible material, they can completely melt and flow out of the shell mold without leaving any residues, ensuring the cleanliness and integrity of the casting cavity.

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

[0086] Preferably, the runner wax is wax of model K512.

[0087] Wax of model K512 has good plasticity and stability, which can ensure high precision when making runners, exhaust devices 4 and slag traps 5 with complex shapes, helps to ensure the geometric precision of the entire gating system, thereby improving the quality of the final casting. Moreover, wax of model K512 has a low melting point and good fluidity, and can completely melt and flow out of the shell mold during the high-temperature dewaxing process without leaving any residues, ensuring the cleanliness of the casting cavity, reducing casting defects caused by residues. Using the same type of wax material to make runners, exhaust devices 4 and slag traps 5 ensures the consistent behavior of these components during the entire 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 the stability and repeatability of the process, and produces fewer volatile substances during the dewaxing process, which is beneficial to protecting the working environment and the health of employees.

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

[0090] S1: Design and preparation; design the positions and sizes of the sprue 1, runner 2, ingate 3, exhaust device 4, slag trap 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 the process requirements to optimize the flow path of the titanium alloy liquid and reduce turbulence and inclusions. This setting reduces casting defects, such as gas holes and shrinkage porosity, through reasonable design, and improves the overall quality and reliability of the casting.

[0092] S2: Making wax pattern components: Use a wax injection machine to inject wax material of model K512 into the mold to form wax patterns of the required shapes;

[0093] Wax of model K512 has good plasticity and stability, ensuring high-precision forming of components with complex shapes. Using the same type of wax material simplifies the production process, reduces costs and complexity. In addition, K512 wax is environmentally friendly and produces fewer volatile substances during the dewaxing process, which is beneficial to protecting the environment and the health of workers.

[0094] S3: Assemble the wax pattern tree: Fix the made sprue 1, runner 2, ingate 3, exhaust device 4 and slag trap ball 5 on the casting wax pattern 6 with adhesive wax to form a complete wax pattern tree structure;

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

[0096] Through the collaborative design of "constant cross-section runner + bottom slag trap ball + top exhaust needle", the problems of molten titanium flow control and impurity removal in titanium alloy joint casting are solved, improving the quality and production efficiency of the casting. The slag trap ball 5 can effectively collect impurities, preventing 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 controlling various potential problems during the casting process, greatly improving the quality and production efficiency of the casting. At the same time, simplifying the production process by using a unified type of wax material enhances the stability and repeatability of the process.

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

[0099] S4: Shell making: Immerse the assembled wax pattern tree in the refractory material slurry multiple times and sprinkle refractory sand to gradually form a solid shell. Let the shell mold harden and dry thoroughly under specific conditions to ensure its strength is sufficient to withstand the subsequent high-temperature dewaxing process;

[0100] S5: Dewaxing and baking: Place the hardened shell mold in the furnace for heating to completely melt and flow out the wax pattern, leaving a cavity as the space for filling with titanium alloy liquid. Further increase the temperature to bake the shell mold to enhance its structural strength and prepare it to receive the pouring of titanium alloy liquid;

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

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

[0103] Example 1

[0104] Taking the TC4 titanium alloy joint of aerospace casting as an example, 120 pieces were put into production. The shortest projection length of a single joint is 90 mm, and the wall thickness is 18 mm. The sprue 1 is Φ45 mm, the cross sprue 2 has a cross-sectional size of 45×35 mm, and there are 4 ingates 3, with a single ingate 3 being Φ25 mm. The technical indicators of the joint castings are statistically shown in Table 1 (the values in the table are average single-piece indicators).

[0105] Table 1. Statistical Results of Technical Indicators of Joint Castings

[0106]

[0107] As can be seen from Table 1, the slag inclusion size of the casting has been reduced from 0.5 - 3 mm in the traditional technology to ≤0.1 mm, the slag inclusion rate has been reduced from 3.2 - 4.5% to ≤0.8%, and the slag collection efficiency is as high as 99.5%. This has greatly improved the internal quality and surface finish of the casting, eliminating the need for additional manual trimming and cleaning work on the casting (the original manual trimming time was 0.35 h), achieving 0 hours of manual trimming time, greatly improving production efficiency, reducing the scrap rate and production cost. No slag inclusion defects were detected in the X-ray imaging of the bulk of the batch products.

[0108] The above are only the 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 principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wax pattern tree structure for investment precision casting of a titanium alloy joint, characterized in that, It includes a sprue (1), a runner (2), an ingate (3), an exhaust device (4) and a slag collecting ball (5); The sprue (1) is arranged along the length direction of the casting wax pattern (6). One end of the sprue (1) is connected to the runner (2). The sprue (1) is used to guide the titanium alloy liquid to smoothly flow from the ladle into the runner (2) and the ingate (3); The runner (2) is arranged along the direction perpendicular to the sprue (1), and is used to evenly distribute the titanium alloy liquid flowing in from the sprue (1) to each ingate (3); The ingate (3) is arranged parallel to the sprue (1). At least two ingates (3) are provided. One end of the ingate (3) is connected to the end of the runner (2) far from the sprue (1). The end of the ingate (3) far from the runner (2) is connected to the casting wax pattern (6). The ingate (3) is used to guide the titanium alloy liquid from the runner (2) to the casting wax pattern (6) and control the flow state of the titanium alloy liquid; The exhaust device (4) is arranged at the top of the casting wax pattern (6) and is used for exhausting slag during pouring at a relatively high superheat degree; The slag collecting ball (5) is arranged at the bottom of the casting wax pattern (6) and is used for impurity sedimentation and collection; 2. The wax pattern tree structure for investment precision casting of the titanium alloy joint according to claim 1, characterized in that, The sprue (1), the runner (2) and the ingate (3) adopt topological design, and the three use a "1-1-N" topological layout, where N≥4; 3. The wax pattern tree structure for investment precision casting of a titanium alloy joint according to claim 1, characterized in that, The cross-sectional area S1 of the sprue (1) = the cross-sectional area S2 of the runner (2) = ∑ the cross-sectional area S3 of the ingates (3), 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 ingate (3); 4. The wax pattern tree structure for investment precision casting of the titanium alloy joint according to claim 1, wherein The sprue (1) is a cylinder with a diameter of Φ30-50mm; 5. The wax pattern tree structure for investment precision casting of a titanium alloy joint according to claim 1, characterized in that, The length L of the runner (2) = N×l, where l = 1.2-1.5 times the shortest projected length of the joint; 6. The wax pattern tree structure for investment precision casting of the titanium alloy joint according to claim 1, characterized in that, The ingate (3) is provided with an inclination angle of 15-25°, so that the titanium alloy liquid is injected along the tangential direction of the cavity wall to reduce turbulence; 7. The wax pattern tree structure for precision investment casting of titanium alloy joints according to claim 1, wherein, 2-4 exhaust devices (4) are provided. The exhaust device (4) is a round bar with a diameter of Φ3mm and a height of 30-50mm, and the slope is 1-1.5°; 8. The wax pattern tree structure for investment precision casting of the titanium alloy joint according to claim 1, characterized in that, The ball diameter D' of the slag collecting ball (5) = Φ20-30mm, the neck diameter d' = Φ10-15mm, and the neck height h' = 0.8-1.5d'; 9. The wax pattern tree structure for investment precision casting of a titanium alloy joint according to claim 1, characterized in that, The exhaust device (4) and the slag collecting ball (5) adopt the same wax as the runner wax. The exhaust device (4) and the slag collecting ball (5) are respectively connected to the casting wax pattern (6) through group welding; 10. A method for manufacturing a wax pattern tree for investment precision casting of a titanium alloy joint, characterized in that, A wax pattern tree structure for precision investment casting of a titanium alloy joint according to any one of claims 1-9 above, specifically comprising the following steps: S1: Design and preparation: Design the positions and dimensions of the sprue (1), the runner (2), the ingate (3), the exhaust device (4), the slag collecting ball (5) and the casting wax pattern (6) according to the specific requirements of the casting; S2: Manufacture the wax pattern assembly: Use a wax injection machine to inject wax material into the mold to form a wax pattern with the required shape; S3: Assemble the wax pattern tree: Fix the made sprue (1), the runner (2), the ingate (3), the exhaust device (4) and the skim bob (5) on the casting wax pattern (6) to form a complete wax pattern tree structure.

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