Titanium alloy casting with long and narrow pipe structure and preparation method and application thereof

Abstract

The application provides a titanium alloy casting with a long and narrow pipe structure and a preparation method and application thereof. In the preparation method, a through hole is formed on a prepared shell at a position corresponding to the two ends of the long and narrow pipe structure; then a graphite pipe is penetrated through the two corresponding through holes on the shell and the two ends of the graphite pipe are exposed; then the shell is poured, the graphite pipe is removed after pouring and forming, and the titanium alloy casting with the long and narrow pipe structure is prepared. The preparation method can effectively reduce the fracture of the ceramic core in the wax mold and the coating process, and the cleaning difficulty after pouring is greatly lower than that of the inlaid ceramic core.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy investment casting technology, specifically to a titanium alloy casting with a narrow and elongated pipe structure, its preparation method, and its application. Background Technology

[0002] Titanium alloy castings for aero engines have multiple cavities, with narrow, elongated pipes being one type of structure. In titanium alloy investment casting, achieving a natural coating for this narrow, elongated pipe structure is difficult, and forming it is also challenging.

[0003] Currently, narrow and long pipe structures are generally formed by inserting ceramic cores. However, ceramic cores are prone to breakage during the coating process, are difficult to clean after casting, and can easily damage the casting body.

[0004] Therefore, it is essential to develop a novel method for forming elongated pipe structures in titanium alloy investment casting processes. Summary of the Invention

[0005] To address the problems in the prior art, the main objective of this invention is to provide a titanium alloy casting with a narrow and elongated pipe structure, its preparation method, and its application. This preparation method can effectively reduce the breakage of ceramic cores during wax molding and coating processes, and the cleaning difficulty after casting is much lower than that of inlaid ceramic cores.

[0006] To achieve the above objectives, according to a first aspect of the present invention, a method for preparing titanium alloy castings with a narrow and elongated pipe structure is provided.

[0007] The method for preparing this titanium alloy casting with a narrow, elongated tubular structure includes the following steps:

[0008] Provide wax models of titanium alloy castings with narrow pipe structures;

[0009] The elongated pipe structure is filled with wax to form a wax rod, with both ends of the wax rod exposed.

[0010] A mold shell is fabricated, and through holes are formed on the mold shell at positions corresponding to both ends of the elongated pipe structure;

[0011] A graphite tube is used to penetrate two corresponding through holes on the shell, with both ends of the graphite tube exposed.

[0012] A casting process is used to cast the shell, and after casting, the graphite tube is removed to obtain a titanium alloy casting with a narrow and long tubular structure.

[0013] Furthermore, the process of creating the molded shell includes the following steps:

[0014] A shell covering the outer side of the wax model of the titanium alloy casting is prepared by a coating sand coating process; wherein both ends of the wax rod are exposed.

[0015] The shell is obtained by dewaxing and baking.

[0016] Furthermore, the diameter of the exposed portion of the wax rod is 0.5 mm larger than the diameter of the elongated tubular structure; the length of the exposed portion of the wax rod is ≥30 mm.

[0017] Furthermore, the diameter of the through hole is the same as the diameter of the exposed portion of the wax rod.

[0018] Furthermore, titanium wire is used as a guide to guide the graphite tube through the two corresponding through holes on the shell.

[0019] Furthermore, the outer diameter of the graphite tube is 7–12 mm; the length of the exposed portion of the graphite tube is ≥30 mm.

[0020] Furthermore, the diameter of the titanium wire is 1 / 3 of the diameter of the through hole;

[0021] Preferably, the length of the titanium wire is greater than or equal to the length of the graphite tube, and the diameter of the titanium wire is less than the inner diameter of the graphite tube.

[0022] Furthermore, a rapid coating process is used to secure the connection between the graphite tube and the shell.

[0023] To achieve the above objectives, according to a second aspect of the present invention, a titanium alloy casting having a narrow tubular structure is provided.

[0024] The titanium alloy casting with a narrow, elongated tubular structure was prepared using the method described above; wherein,

[0025] The diameter of the elongated pipe structure is 7–12 mm, and the length is 200–350 mm.

[0026] To achieve the above objectives, according to a third aspect of the present invention, an application of a titanium alloy casting having a narrow tubular structure is provided.

[0027] Application of titanium alloy castings with narrow tubular structures prepared by the above method in aero-engines.

[0028] This invention proposes a novel method for forming a narrow tubular structure in titanium alloy investment casting. First, through holes are formed on the shell at corresponding positions at both ends of the narrow tubular structure. Then, graphite tubes are used to penetrate the corresponding two through holes on the shell. After casting, the shell is cast using a pouring process. After casting, the graphite tubes are removed, resulting in a titanium alloy casting with a narrow tubular structure. This method can effectively reduce the breakage of ceramic cores during wax pattern and coating processes, and the cleaning difficulty after casting is much lower than that of inlaid ceramic cores.

[0029] Advantages of this invention:

[0030] 1. The compressive strength of high-purity graphite is generally 45Mpa to 80Mpa, while the compressive strength of ceramic materials is generally above 200Mpa. Graphite is easier to clean than ceramic.

[0031] 2. Graphite is prone to oxidation in atmospheric and high-temperature environments. This invention employs a method of placing a graphite tube into a calcined shell to prevent graphite from oxidizing in the atmosphere or during the calcination process.

[0032] 3. The present invention forms a casting by vacuum melting and casting. Taking advantage of the low compressive strength and easy cleaning of graphite, the graphite is cleaned to form a narrow and elongated pore structure. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0034] Figure 1 A schematic cross-sectional view of a titanium alloy casting wax model with a narrow and elongated pipe structure provided in an embodiment of the present invention;

[0035] Figure 2 for Figure 1 A schematic diagram of the cross-section along the AA direction;

[0036] Figure 3 A schematic cross-sectional view of the titanium alloy casting wax model after forming the wax rod in an embodiment of the present invention;

[0037] Figure 4 A schematic cross-sectional view of a titanium alloy casting with a graphite tube after casting in an embodiment of the present invention;

[0038] Figure 5 for Figure 4 Enlarged view of the structure of section K in the middle.

[0039] In the picture:

[0040] 1. Narrow and elongated pipe structure; 2. Titanium alloy casting wax model; 3. Wax rod; 4. Graphite tube;

[0041] 5. Titanium wire; 6. Titanium alloy castings. Detailed Implementation

[0042] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0043] This invention provides a novel method for preparing titanium alloy castings with narrow and elongated tubular structures using investment casting.

[0044] The method for preparing titanium alloy castings with elongated tubular structures in this invention specifically includes the following steps:

[0045] 1) Provide 2 wax models of titanium alloy castings, such as Figures 1-2 As shown, the titanium alloy casting wax model 2 has a narrow and elongated pipe structure 1.

[0046] In an embodiment of the present invention, the diameter of the elongated pipe structure 1 is in the range of 7 to 12 mm, and the length is in the range of 200 to 350 mm.

[0047] In some embodiments of the present invention, the elongated pipe structure 1 has a diameter of 7 mm and a length of 300 mm.

[0048] 2) Fill the narrow pipe structure 1 with wax to form a wax rod 3, with both ends of the wax rod 3 exposed, such as... Figure 3 As shown.

[0049] In an embodiment of the present invention, the wax rod 3, which is designed to be a solid structure for filling the elongated tube structure 1 with wax, has a diameter greater than the diameter of the elongated tube structure 1.

[0050] In some embodiments of the present invention, the diameter of the exposed portion of the wax rod 3 is 0.5 mm larger than the diameter of the elongated tubular structure 1.

[0051] In some embodiments of the present invention, the length of the exposed portion of the wax rod 3 is ≥30mm.

[0052] Of course, the diameter and length of the exposed part of wax rod 3 can be adjusted according to the actual operational needs to meet the actual production requirements.

[0053] 3) A shell is made by coating and sand coating process to cover the outer side of the wax model 1 of the titanium alloy casting; wherein both ends of the wax rod 3 are exposed.

[0054] It is worth mentioning that during the production process, the exposed part of the wax rod 3 is protected when each layer of coating is applied. When drying, the protective measures are removed. This process is repeated until a shell is finally produced that wraps around the outside of the titanium alloy casting wax mold 1 and exposes both ends of the wax rod 3.

[0055] 4) Dewaxing and firing to obtain a mold shell, and forming through holes at positions corresponding to both ends of the elongated tube structure 1 on the mold shell. The diameter of the through hole is the same as the diameter of the exposed part of the wax rod 3.

[0056] In an embodiment of the present invention, after baking and dewaxing, the exposed wax rods 3 at both ends, that is, the exposed parts of the wax rods 3, are liquefied and flow out. Through holes are formed on the shell at the positions corresponding to the two ends of the narrow tube, such as through holes with a diameter of 7.5 mm.

[0057] It is worth mentioning that, in the embodiments of the present invention, electro-dewaxing can be used, with a dewaxing temperature of 300-400℃ and a dewaxing time of not less than 2.0h; and calcination at a temperature above 1000℃ for a high-temperature calcination time of not less than 4h.

[0058] 5) The graphite tube 4 penetrates the two corresponding through holes on the shell, and both ends of the graphite tube 4 are exposed.

[0059] In an embodiment of the present invention, a titanium wire 5 can be used as a guide to pass the graphite tube 4 through two corresponding through holes on the shell. That is, the graphite tube 4 is inserted into one through hole on the shell and exits from the other through hole corresponding to that through hole, and both ends of the graphite tube 4 are exposed.

[0060] In some embodiments of the present invention, the length of the exposed portion of the graphite tube 4 is ≥30mm.

[0061] In an embodiment of the present invention, the outer diameter of the graphite tube 4 is in the range of 7 to 12 mm.

[0062] In an embodiment of the present invention, the diameter of the titanium wire 5 is 1 / 3 of the diameter of the through hole.

[0063] In an embodiment of the present invention, the length of the titanium wire 5 is greater than or equal to the length of the graphite tube 4, and the diameter of the titanium wire 5 is less than the inner diameter of the graphite tube 4.

[0064] In some embodiments of the present invention, the titanium wire 5 has a diameter of 2.5 mm and a length of 400 mm.

[0065] It is worth mentioning that, in order to improve the firmness of the graphite tube 4 after it passes through the corresponding two through holes on the shell, a rapid coating process can be used to fix the two ends of the graphite tube 4 to secure the connection between the graphite tube 4 and the shell.

[0066] 6) The casting process is used, such as static casting, to cast the shell. See the attached diagram for the structure after casting. Figures 4-5 As shown, the graphite tube 4 can then be broken and cleaned by vibration, and finally a titanium alloy casting 6 with a narrow tube structure is obtained.

[0067] It should be noted that the rapid coating process and static casting process in this invention are conventional production processes in the prior art, and their process parameters can be designed according to actual needs, which will not be elaborated further.

[0068] According to a specific embodiment of the present invention, the present invention also provides a titanium alloy casting with a narrow pipe structure.

[0069] The titanium alloy casting with a narrow, elongated tubular structure is prepared using the method described above. The diameter of the narrow, elongated tubular structure in the titanium alloy casting is 7–12 mm, and its length is 200–350 mm.

[0070] According to a specific embodiment of the present invention, the titanium alloy casting with a narrow and elongated pipe structure prepared by the preparation method of the present invention can be applied to aero engines as a titanium alloy casting for aero engines.

[0071] It should be noted that the term "comprising" and any variations thereof in the specification and claims of this invention are intended to cover non-exclusive inclusion, for example, including a series of components that are not necessarily limited to those explicitly listed, but may include other components that are not explicitly listed or that are inherent to the component.

[0072] In this invention, the terms "upper," "lower," "bottom," "top," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0073] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0074] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0075] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of producing a titanium alloy casting having a long and narrow pipe structure, characterized by, The method comprises the following steps: providing a wax mold of a titanium alloy casting with a long and narrow pipe structure; filling the long and narrow pipe structure with wax along the axial direction to form a wax rod, and the two ends of the wax rod are exposed; making a mold shell with two through holes corresponding to the two ends of the long and narrow pipe structure, wherein the two ends of the wax rod are exposed, and the mold shell is made by using a coating sand hanging process to obtain a shell body wrapped outside the wax mold of the titanium alloy casting, and then decanning and baking to obtain the mold shell; using a graphite pipe to pass through the two corresponding through holes of the mold shell, and the two ends of the graphite pipe are exposed; using a pouring process to pour the mold shell, removing the graphite pipe after pouring and shaping to obtain a titanium alloy casting with a long and narrow pipe structure.

2. The method of producing a titanium alloy casting having a long and narrow pipe structure according to claim 1, wherein The diameter of the exposed part of the wax rod is 0.5 mm larger than the diameter of the long and narrow pipe structure, and the length of the exposed part of the wax rod is greater than or equal to 30 mm.

3. The method of producing a titanium alloy casting having a long and narrow pipe structure according to claim 1 or 2, characterized in that, The diameter of the through hole is the same as the diameter of the exposed part of the wax rod.

4. The method of producing a titanium alloy casting having a long and narrow pipe structure according to claim 1, characterized by, Titanium wire is used to guide the graphite pipe to pass through the two corresponding through holes of the mold shell.

5. The method of producing a titanium alloy casting having a long and narrow pipe structure according to claim 1 or 4, characterized in that, The outer diameter of the graphite pipe is 7-12 mm, and the length of the exposed part of the graphite pipe is greater than or equal to 30 mm.

6. The method of producing a titanium alloy casting having a long and narrow pipe structure according to claim 4, wherein The diameter of the titanium wire is 1 / 3 of the diameter of the through hole.

7. The method of producing a titanium alloy casting having a long and narrow pipe structure according to claim 4, wherein The length of the titanium wire is greater than the length of the graphite pipe, and the diameter of the titanium wire is less than the inner diameter of the graphite pipe.

8. The method of producing a titanium alloy casting having a long and narrow pipe structure according to claim 1, wherein The graphite pipe is fastened at the connection with the mold shell by using a rapid coating process.

9. A titanium alloy casting having an elongated tubular structure, characterized by, The titanium alloy casting with a long and narrow pipe structure is prepared by using the preparation method of any one of claims 1-8, wherein The diameter of the long and narrow pipe structure is 7-12 mm, and the length is 200-350 mm.

10. The titanium alloy casting with a long and narrow pipe structure prepared by the preparation method of any one of claims 1-8 is applied in an aero-engine.

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