An integrated casting method for titanium alloy components and a ceramic core coating apparatus

Abstract

The application discloses a kind of integral casting methods of titanium alloy component, it is related to the field of precision casting, the application adopts titanium alloy investment casting or graphite precision casting process scheme, and the ceramic core of the alkaline ceramic core such as calcium oxide (or magnesium oxide) + yttrium oxide composite structure is directly placed into the cavity of grid-shaped framework, and the grid-shaped framework and skin contained in titanium alloy rudder core product are directly cast into shape, then the ceramic core is removed by acid boiling or dilute acid soaking process;The scheme can replace the manufacturing scheme of casting framework + framework precision machining + upper and lower two surface skin laser welding currently widely used in the industry, and direct 3D printing process scheme.The application has the advantages of short process flow, high product forming precision, manufacturing cost is far lower than the above two manufacturing schemes and the like.

Description

Technical Field

[0001] This invention relates to the field of precision casting, specifically to an integral casting method for titanium alloy components and a ceramic core coating device. Background Technology

[0002] Titanium alloys possess excellent properties such as high specific strength, high heat resistance, and excellent corrosion resistance, making them high-quality lightweight metal structural materials that are widely used in aerospace and other fields.

[0003] Air rudders are critical components of aircraft, controlling their flight attitude through rotation. Mounted externally, they withstand harsh thermal environments and force loads during high-speed flight, requiring designs focused on heat insulation and load-bearing capacity. Air rudders typically consist of a rudder core and a rudder shaft. During flight, aerodynamic pressure acts on the rudder core, providing the power for control. To improve flight distance, the rudder core weight must be strictly controlled, and its internal cavity is usually designed with a mesh-like skeleton structure. Currently, there are generally two manufacturing methods for titanium alloy rudder cores: Method 1 involves casting the mesh skeleton, which is then machined and laser-welded to the upper and lower skins. This method has many production steps, a long cycle, and high costs. After casting, the skeleton requires precision machining before laser welding to the skin. Method two involves directly 3D printing titanium alloy rudder cores. This method directly prints the mesh skeleton and skin, eliminating the machining process of the mesh skeleton and the laser welding process between the mesh skeleton and the skin. Its advantages are fewer production steps and a shorter production cycle; its disadvantages are the high cost of titanium alloy powder and the expensive price of 3D printing equipment. Aircraft air intake ducts are the air intake and exhaust systems of aircraft engines, typically with complex internal structures.

[0004] As aircraft performance requirements continue to rise, the internal cavity structure of air intake products is evolving towards thinner wall thicknesses, higher surface quality requirements, and higher dimensional accuracy. Previously used titanium alloy casting processes are insufficient to produce qualified air intake products with complex structures; currently, the commonly adopted manufacturing process is 3D printing for direct molding.

[0005] Investment casting is an effective method for producing high-precision, low-roughness, and complex-shaped castings, particularly suitable for casting expensive and difficult-to-machine metals. As a primary method for producing ceramic-core artificial joints, high-temperature alloy guide vanes, and complex structural components, it has become an important aspect of advanced manufacturing technology. In investment casting, the internal cavity is mostly formed along with the external shape through methods such as applying coatings and sprinkling molding sand. When the internal cavity is too narrow, has a complex shape, or cannot be dried and hardened, a pre-prepared ceramic core must be used to form the internal cavity. In the precision casting of hollow products, the ceramic core largely determines the dimensional accuracy, yield rate, and casting cost. Titanium alloy investment casting is more complex than investment casting for other materials. Currently, the industry commonly uses a process to prefabricate zirconia or silica ceramic cores to form the inner cavity of the casting. After casting, the ceramic cores remaining in the inner cavity are removed by an alkaline boiling process. This process has several drawbacks: zirconia ceramic cores are too expensive, and the alkaline boiling process is lengthy and complex, leading to a significant increase in casting costs, which is unsuitable for the current cost-saving requirements of aircraft products. Furthermore, the silica ceramic cores react violently with the molten titanium alloy, resulting in poor surface roughness of the casting, requiring welding and polishing, which is insufficient to meet the surface quality and dimensional accuracy requirements of the inner cavity of current aircraft castings. Summary of the Invention

[0006] The purpose of this invention is to provide an integral casting method for titanium alloy components, which overcomes the technological problems and high mass production costs encountered in the prior art for complex component products.

[0007] The technical solution adopted in this invention is as follows: A method for integral casting of titanium alloy components, comprising the following steps:

[0008] S1. Core preparation: Based on the cavity size and structure of the product, use calcium oxide or magnesium oxide to manufacture a ceramic core that conforms to its cavity size and structure.

[0009] S2. Preparation of composite ceramic core: Yttrium oxide slurry is uniformly coated on the surface of the ceramic core and baked at high temperature to prepare composite ceramic core;

[0010] S3. Wax model preparation: The above-mentioned composite ceramic core is placed in a metal mold, and a wax model is prepared using a wax injection machine. The cavity of the prepared grid-like skeleton wax model with surface skin is occupied by the composite ceramic core.

[0011] S4. Shell mold preparation: After cleaning and welding the wax mold, the shell mold is prepared according to the investment casting shell making process. Normal steam dewaxing and baking are carried out to finally complete the shell mold preparation.

[0012] S5. Vacuum casting: Casting is carried out using a vacuum consumable arc casting furnace, and titanium liquid is poured into the shell mold using a static pouring process;

[0013] S6. Removal of composite ceramic core: After casting, the gating system of the casting is removed and sandblasted. Then, the casting is soaked in dilute sulfuric acid to remove the composite ceramic core.

[0014] Furthermore, in step S2, the ceramic core is baked at a temperature of 1050°C for 6 hours.

[0015] Furthermore, in step S5, the casting material used is ZTA15, the melting current is 21000-21000A, and the melting voltage is 38-40V.

[0016] Furthermore, in step S6, the casting is immersed in sulfuric acid for 20-30 minutes.

[0017] A ceramic core coating device includes a frame, a slurry tank, a coating mechanism, support legs, a cylinder, a pressure pipe, and a material placement platform;

[0018] The cylinder is installed below the frame, and the slurry tank is installed at the end of the cylinder's telescopic rod. The coating mechanism is evenly installed on the lower surface of the slurry tank. The material placement platform for preventing the ceramic core from being placed is provided below the coating mechanism, and the material placement platform is supported by the support legs.

[0019] The coating mechanism includes a valve core, valve hole, tension spring, liquid guide tube, sponge block, limit cap, and valve body;

[0020] The valve core is coaxially arranged inside the valve body, and the valve hole is opened on the outside of the valve core. The lower end of the valve body is provided with a limiting cover for limiting the axial position of the valve core. The tension spring is provided between the limiting cover and the valve core. The liquid guide tube is connected to the bottom of the valve core. The liquid guide tube passes through the limiting cover and is fitted with the sponge block.

[0021] Furthermore, the liquid guiding tube includes a first liquid guiding tube, a limiting ring, a spring, and a tension spring 6;

[0022] The lower end of the first liquid guide tube is inserted into the tension spring, and the limiting ring is sleeved on the outside of the first liquid guide tube. The spring is arranged between the limiting ring and the end of the tension spring, and the elastic coefficient of the spring is greater than that of the tension spring.

[0023] Furthermore, a guide rod is provided on the upper surface of the slurry tank in the vertical direction. The guide rods are diagonally distributed, and their upper ends pass through the frame and extend out of the frame.

[0024] Furthermore, the outer side of the material placement platform is uniformly provided with positioning devices for fixing the position of the ceramic core. The positioning device includes a mounting plate and a positioning cylinder. The mounting plate is fixed on the material placement platform, the cylinder body of the positioning cylinder is fixed on the mounting plate, and its telescopic rod passes through the mounting plate and is fixed with a fixing block.

[0025] Furthermore, the outrigger includes a support rod, a positioning bolt, and a sleeve, with the lower end of the support rod extending into the sleeve, and the positioning bolt passing through the sleeve and abutting against the support rod.

[0026] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0027] 1. This invention employs a titanium alloy investment casting or graphite precision casting process, directly placing an alkaline ceramic core (such as calcium oxide) + yttrium oxide composite structure into the cavity of a mesh-like skeleton, directly casting the mesh-like skeleton and skin of the titanium alloy rudder core product. The ceramic core is then removed via acid boiling or dilute acid immersion. This method can replace the currently prevalent industry manufacturing methods of casting the skeleton + precision machining of the skeleton + laser welding of the upper and lower skins, as well as direct 3D printing. This invention has significant advantages such as a shorter process flow, higher product forming accuracy, and manufacturing costs far lower than the above two methods.

[0028] 2. The ceramic core coating equipment of the present invention, by bringing the slurry tank with coating mechanism all over it into contact with the ceramic core, only the solid part of the ceramic core will trigger the coating mechanism, so that the yttrium oxide slurry can be coated onto the surface of the ceramic core through the coating mechanism. Therefore, it is suitable for most complex shaped ceramic cores, and at the same time, it will not cause slurry waste.

[0029] 3. In this invention, to prevent excessive impact between the liquid guide tube and the ceramic core during the upward movement of the liquid guide tube, which could lead to bending of the liquid guide tube, the liquid guide tube is divided into two parts, a first liquid guide tube and a second liquid guide tube, which are inserted into each other. When the liquid guide tube is impacted, the first liquid guide tube can be submerged in the second liquid guide tube. At the same time, to prevent the valve core from being unable to be pushed upward after the first liquid guide tube is submerged in the second liquid guide tube, a spring is provided between the second liquid guide tube and the limiting ring sleeved on the outside of the first liquid guide tube. The elastic coefficient of the spring is greater than that of the tension spring, so as to ensure that only the impact that the liquid guide tube continues to suffer after the valve core is pushed upward will cause the first liquid guide tube to be submerged in the second liquid guide tube.

[0030] 4. In order to ensure the stability of the slurry bucket when it moves downward, the present invention provides guide rods on the upper surface of the slurry bucket in the vertical direction. The guide rods are diagonally distributed, and their upper ends pass through the frame and extend out of the frame. The guide rods guide the slurry bucket when it moves up and down, so as to make its movement stable and thus improve the coating quality.

[0031] 5. In this invention, since the volume of each ceramic core is different, but the extension distance of the cylinder is fixed, if the ceramic core is too large or too small, it will not be able to effectively trigger the coating mechanism. Therefore, the height of the support leg is adjustable, and the height of the support leg can be adjusted according to the volume of the ceramic core, so as to ensure the distance between the ceramic core and the coating mechanism. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the titanium alloy rudder core described in this invention;

[0033] Figure 2 This is a front view of the ceramic core coating equipment in this invention;

[0034] Figure 3 This is a left view of the ceramic core coating equipment in this invention;

[0035] Figure 4 This is a schematic diagram of the coating mechanism in this invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Frame; 2. Slurry tank; 3. Coating mechanism; 301. Valve core; 302. Valve hole; 303. Tension spring; 304. First liquid guide tube; 306. Limiting ring; 307. Spring; 308. Tension spring; 309. Sponge block; 310. Limiting cover; 311. Valve body; 4. Positioning cylinder; 5. Support leg; 51. Support rod; 52. Positioning bolt; 53. Sleeve; 6. Mounting plate; 7. Guide rod; 8. Feed port; 9. Cylinder; 10. Pressurization pipe; 11. Material placement platform. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0040] Example 1

[0041] A method for integral casting of a titanium alloy rudder core product includes the following steps:

[0042] S1. Core preparation: Based on the cavity size and structure of the product, use calcium oxide or magnesium oxide to manufacture a ceramic core that conforms to its cavity size and structure.

[0043] S2. Preparation of composite ceramic core: Yttrium oxide slurry is uniformly coated on the surface of the ceramic core and baked at high temperature to produce composite ceramic core;

[0044] S3. Wax model preparation: The above-mentioned composite ceramic core is placed in a metal mold, and a wax model is prepared using a wax injection machine. The cavity of the prepared grid-like skeleton wax model with surface skin is occupied by the composite ceramic core.

[0045] S4. Shell mold preparation: After cleaning and welding the wax mold, the shell mold is prepared according to the investment casting shell making process. Normal steam dewaxing and baking are carried out to finally complete the shell mold preparation.

[0046] S5. Vacuum casting: Casting is carried out using a vacuum consumable arc casting furnace, and titanium liquid is poured into the shell mold using a static pouring process;

[0047] S6. Removal of composite ceramic core: After casting, the gating system of the casting is removed and sandblasted. Then, the casting is soaked in dilute sulfuric acid to remove the composite ceramic core.

[0048] Example 2

[0049] The difference between this embodiment and embodiment 1 is that in step S2, the baking temperature of the ceramic core is 6 hours and the baking temperature is 1050℃.

[0050] Example 3

[0051] The difference between this embodiment and embodiment 1 is that in step S5, the casting material used is ZTA15, the melting current is 21000-21000A, and the melting voltage is 38-40V.

[0052] Example 4

[0053] The difference between this embodiment and Embodiment 1 is that in step S6, the immersion time of the casting in sulfuric acid is 20-30 minutes.

[0054] Example 5

[0055] In step S2 of the embodiment, when applying yttrium oxide to the surface of the ceramic core, since the ceramic core is made according to the shape of the component and the shape of the ceramic core is relatively complex, applying it over a large area can increase the application efficiency, but applying the slurry to some openings on the surface of the ceramic core will cause waste of the slurry. Therefore, the application process is cumbersome and affects work efficiency.

[0056] A ceramic core coating device includes a frame 1, a slurry tank 2, a coating mechanism 3, support legs 5, a cylinder 9, a pressure pipe 10, and a material placement platform 11.

[0057] A cylinder 9 is installed below the frame 1. A slurry tank 2 is installed at the end of the telescopic rod of the cylinder 9. A coating mechanism 3 is evenly installed on the lower surface of the slurry tank 2. A material placement platform 11 for preventing the ceramic core from being placed is set below the coating mechanism 3. The material placement platform 11 is supported by support legs 5.

[0058] The coating mechanism 3 includes a valve core 301, a valve hole 302, a tension spring 303, a liquid guide tube, a sponge block 309, a limit cover 310, and a valve body 311;

[0059] A valve core 301 is coaxially arranged inside the valve body 311. A valve hole 302 is opened on the outside of the valve core 301. A limiting cover 310 for limiting the axial position of the valve core 301 is provided at the lower end of the valve body 311. A tension spring 303 is provided between the limiting cover 310 and the valve core 301. A liquid guide tube is connected below the valve core 301. After the liquid guide tube passes through the limiting cover 310, a sponge block 309 is installed.

[0060] The ceramic core to be coated with yttrium oxide is placed on the material placement platform 11. The cylinder 9 drives the slurry tank 2 to move downward. When the slurry tank 2 moves downward, the coating mechanism 3 on its lower surface first touches the ceramic core. When the solid part of the ceramic core touches the coating mechanism 3, it pushes the valve core 301 upward through the liquid guide tube. At the same time as the valve core 301 moves upward, the tension spring 303 is stretched, pushing the valve core 301 into the slurry tank 2. The yttrium oxide slurry stored in the slurry tank 2 enters the valve core 301 through the valve hole 302 and reaches the sponge block 309 at its lower end along the liquid guide tube. The sponge block 309 is soaked with yttrium oxide slurry, thereby applying the yttrium oxide slurry to the surface of the ceramic core. When the cylinder 9 drives the slurry tank 2 to reset, the tension spring 303 returns to its original state, pulling the valve core 301 back into the valve body 311, preventing the slurry from continuing to flow into the liquid guide tube.

[0061] To facilitate slurry discharge, the slurry tank 2 is connected to a pressurizing device via a pressurizing pipe 10, and the slurry tank 2 is equipped with a feeding port 8 for adding yttrium oxide slurry.

[0062] Example 6

[0063] The difference between this embodiment and embodiment 5 is that, in order to avoid excessive movement range when the liquid guide tube comes into contact with the ceramic core, which would cause damage to the liquid guide tube, the liquid guide tube is set as a split type, wherein the liquid guide tube includes a first liquid guide tube 304, a limiting ring 306, a spring 307 and a second liquid guide tube 308.

[0064] The lower end of the first liquid guide tube 304 is inserted into the second liquid guide tube 308. A limiting ring 306 is sleeved on the outside of the first liquid guide tube 304. A spring 307 is provided between the limiting ring 306 and the end of the second liquid guide tube 308. The elastic coefficient of the spring 307 is greater than that of the tension spring 303.

[0065] During the upward movement of the liquid guide tube, if the impact between it and the ceramic core is too great, it may cause the liquid guide tube to bend. Therefore, the liquid guide tube is divided into two parts, the first liquid guide tube 304 and the second liquid guide tube 308, which are inserted into each other. When the liquid guide tube is impacted, the first liquid guide tube 304 can be submerged in the second liquid guide tube 308. At the same time, in order to prevent the valve core 301 from being unable to be pushed upward after the first liquid guide tube 304 is submerged in the second liquid guide tube 308, a spring 307 is set between the second liquid guide tube 308 and the limiting ring 306 sleeved on the outside of the first liquid guide tube 304. The elastic coefficient of the spring 307 is greater than that of the tension spring 303. This ensures that only the impact that the liquid guide tube continues to suffer after pushing the valve core 301 upward will cause the first liquid guide tube 304 to be submerged in the second liquid guide tube 308.

[0066] Example 7

[0067] The difference between this embodiment and embodiment 5 is that, in order to ensure the stability of the slurry bucket 2 when it moves downward, a guide rod 7 is provided on the upper surface of the slurry bucket 2 in the vertical direction. The guide rod 7 is diagonally distributed, and its upper end passes through the frame 1 and extends out of the frame 1. The guide rod 7 guides the slurry bucket 2 when it moves up and down, so that its movement is stable and thus improves the coating quality.

[0068] Example 8

[0069] The difference between this embodiment and embodiment 5 is that: positioning devices for fixing the position of ceramic cores are evenly arranged on the outer side of the material placement platform 11. The positioning devices include a mounting plate 6 and a positioning cylinder 4. The mounting plate 6 is fixed on the material placement platform 11, and the cylinder body of the positioning cylinder 4 is fixed on the mounting plate 6. Its telescopic rod passes through the mounting plate 6 and is fixed with a fixing block. The ceramic core is placed between the positioning devices, and the telescopic rod of the positioning cylinder 4 is controlled to extend to fix the ceramic core.

[0070] Example 9

[0071] The difference between this embodiment and embodiment 5 is that the volume of each ceramic core is different, but the extension distance of the cylinder 9 is fixed. If the ceramic core is too large or too small, it cannot effectively trigger the coating mechanism 3. Therefore, the height of the support leg 5 is adjustable. The height of the support leg 5 is adjusted according to the volume of the ceramic core to ensure the distance between the ceramic core and the coating mechanism 3.

[0072] The outrigger 5 includes a support rod 51, a positioning bolt 52, and a sleeve 53. The lower end of the support rod 51 extends into the sleeve 53, and the positioning bolt 52 passes through the sleeve 53 and abuts against the support rod 51.

Claims

1. A ceramic core coating device, comprising a frame (1), a slurry tank (2), a coating mechanism (3), support legs (5), a cylinder (9), a pressure pipe (10), and a material placement platform (11); The cylinder (9) is installed below the frame (1), the slurry tank (2) is installed at the end of the telescopic rod of the cylinder (9), the coating mechanism (3) is evenly installed on the lower surface of the slurry tank (2), and the material placement platform (11) for placing ceramic cores is set below the coating mechanism (3). The material placement platform (11) is supported by the support leg (5). The coating mechanism (3) includes a valve core (301), a valve hole (302), a tension spring (303), a liquid guide tube, a sponge block (309), a limiting cap (310), and a valve body (311). The valve core (301) is coaxially arranged inside the valve body (311), and the valve hole (302) is opened on the outside of the valve core (301). The lower end of the valve body (311) is provided with the limiting cover (310) for limiting the axial position of the valve core (301). The tension spring (303) is provided between the limiting cover (310) and the valve core (301). The liquid guide tube is connected below the valve core (301). The liquid guide tube passes through the limiting cover (310) and the sponge block (309) is installed thereon. The liquid guide tube includes a first liquid guide tube (304), a limiting ring (306), a spring (307), and a second liquid guide tube (308); The lower end of the first liquid guide tube (304) is inserted into the second liquid guide tube (308). The limiting ring (306) is sleeved on the outside of the first liquid guide tube (304). The spring (307) is provided between the limiting ring (306) and the end of the second liquid guide tube (308). The elastic coefficient of the spring (307) is greater than that of the tension spring (303).

2. The ceramic core coating equipment according to claim 1, characterized in that: The upper surface of the slurry tank (2) is provided with guide rods (7) in the vertical direction. The guide rods (7) are diagonally distributed, and their upper ends pass through the frame (1) and extend out of the frame (1).

3. The ceramic core coating equipment according to claim 1, characterized in that: The outer side of the material placement platform (11) is uniformly provided with positioning devices for fixing the position of the ceramic core. The positioning device includes a mounting plate (6) and a positioning cylinder (4). The mounting plate (6) is fixed on the material placement platform (11), and the cylinder body of the positioning cylinder (4) is fixed on the mounting plate (6). Its telescopic rod passes through the mounting plate (6) and is fixed with a fixing block.

4. The ceramic core coating equipment according to claim 1, characterized in that: The outrigger (5) includes a support rod (51), a positioning bolt (52) and a sleeve (53). The lower end of the support rod (51) extends into the sleeve (53), and the positioning bolt (52) passes through the sleeve (53) and abuts against the support rod (51).

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