Additive manufacturing method for titanium alloy complex shell structure and hot sizing tool

Abstract

The invention provides an additive manufacturing method and a hot sizing tool for a titanium alloy complex shell structure, and the method comprises the following steps: (1) adopting multi-technology fusion, and formulating a total additive manufacturing process scheme with less support and hot sizing for the titanium alloy complex shell structure; (2) obtaining the size of the molded surface of the hot sizing tool and the shell printing shape control requirement; (3) designing the structure of a hot sizing tool; (4) obtaining a shell model with a shape control support; (5) printing and forming a shell blank with a shape control support by using selective laser melting forming equipment; (6) the shell blank is subjected to powder cleaning; (7) the inner molded surface of the shell blank subjected to powder removal is coated with a solder resist, a hot shape correction tool is installed in the shell blank, heat treatment is conducted, and hot shape correction is achieved; and (8) the shell blank is separated from the base plate, and the titanium alloy complex shell blank is obtained. The technical problems that in the prior art, a titanium alloy complex shell structure additive manufacturing method is high in cost and low in product quality can be solved.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, and particularly relates to an additive manufacturing method and thermal shaping tooling for complex titanium alloy shell structures. Background Technology

[0002] The titanium alloy shell has a spherical end cap structure at one end, and the remaining section is a cylindrical body with a wall thickness of 2.5mm. Four square window openings and boss structures are evenly distributed on the outer cylindrical surface. Traditionally, casting can be used to manufacture the blank. For engine parts, such as titanium alloy shells, traditional casting requires pre-machining with allowances throughout to ensure dimensional accuracy. In small-batch, multi-state trial production stages, casting requires specialized molds, resulting in high costs and long lead times.

[0003] Selective laser melting (additive manufacturing) technology uses lasers to selectively melt metal powder and then stacks it layer by layer according to the product's digital model to form parts. It is not affected by the complexity of the parts, does not rely on molds, and has the characteristics of short manufacturing cycle and fast response speed.

[0004] Using additive manufacturing to print titanium alloy shell parts during the pilot production phase can effectively reduce costs and time. However, relying solely on the time-saving advantage of additive manufacturing during the pilot phase is not inexpensive and results in poor consistency. To achieve the design requirement of ±0.5mm in the printing of titanium alloy shells, a large number of shape control supports are needed, weighing up to 9kg, accounting for 69% of the weight of the shell blank. While the cost of these numerous shape control supports is not a major concern during the pilot production phase due to their high consumption of powder materials and printers, this disadvantage becomes more pronounced in mass production. The advantages compared to traditional casting processes gradually diminish, and the cost may even exceed that of traditional processes. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0006] According to one aspect of the present invention, an additive manufacturing method for complex titanium alloy shell structures is provided, the method comprising:

[0007] (1) Based on the characteristics of complex titanium alloy shell structures, a multi-technology integration approach was adopted to develop an overall additive manufacturing process scheme for complex titanium alloy shell structures with minimal support and thermal straightening.

[0008] (2) Based on the overall additive manufacturing process scheme, combined with the material parameters of the complex titanium alloy shell and the thermal straightening tooling, the dimensions of the thermal straightening tooling surface and the shell printing shape control requirements are obtained;

[0009] (3) Based on the dimensions of the hot-forming tooling surface and the complex titanium alloy shell structure, design the structure of the hot-forming tooling;

[0010] (4) Based on the overall additive manufacturing process scheme and combined with the complex titanium alloy shell structure, a preliminary shape control support structure is designed; the shape control support structure is optimized by simulation iteration, and a shell model with shape control support is obtained in combination with the shell printing shape control requirements;

[0011] (5) Use laser selective melting forming equipment to print a shell blank with shape control support;

[0012] (6) Clean the shell blank;

[0013] (7) Apply solder resist to the inner surface of the shell blank after powder removal, install the heat-correcting fixture into the shell blank, and perform heat treatment to achieve heat correction.

[0014] (8) Separate the shell blank from the substrate, remove the shape control support on the outside of the shell blank, grind the outer surface of the shell, and obtain a complex titanium alloy shell blank.

[0015] Furthermore, the complex titanium alloy shell is made of TA15 titanium alloy, and the hot-forming tooling is made of stainless steel.

[0016] Further, in step (2), the shell printing shape control requirements are obtained based on the difference between the outer diameter of the thermal correction tool at room temperature and the inner diameter of the shell cylinder; the outer diameter of the thermal correction tool at room temperature is obtained based on D'T=D't / (a'×(tT)+1), where D'T is the diameter of the outer circle of the thermal correction tool at room temperature, D't is the outer diameter of the thermal correction tool at high temperature, a' is the linear expansion coefficient of the thermal correction tool material, t is the high temperature state temperature, and T is the room temperature state temperature.

[0017] Furthermore, the outer diameter D't of the high-temperature heat-correcting tooling is consistent with the inner diameter Dt of the shell cylinder at high temperature, where Dt = a × (tT) × DT + DT, and a is the linear expansion coefficient of the shell material, and DT is the diameter of the inner diameter of the shell cylinder at room temperature.

[0018] Furthermore, the thermal straightening fixture includes a central body and multiple sub-body parts. The sub-body parts are evenly distributed around the central body and are detachably connected to the central body. The structure of the outer side of the sub-body parts is adapted to the structure of the inner surface of the shell cylinder.

[0019] Furthermore, in step (4), Simufact Additive is used to perform simulation iteration optimization of the shape control support structure.

[0020] Furthermore, after iterative optimization, a V-shaped thin plate shape control support structure is adopted and attached to the outer surface of the complex titanium alloy shell.

[0021] Further, in step (5), the shell model obtained in step (4) is sliced ​​using a large layer thickness parameter to obtain a printing package. TA15 titanium alloy powder is used to print the shell in a laser selective melting forming equipment to obtain a deposited shell blank with a shape control support structure grown on a titanium alloy substrate.

[0022] Furthermore, in step (7), the hot-forming tooling is subjected to vacuum heat treatment along with the shell blank, the product is annealed to relieve stress, and the mechanical properties are adjusted. The high expansion coefficient of the hot-forming tooling material is used to fit the complex inner wall of the shell at high temperature for hot-forming. The shell size tolerance is no more than ±0.5mm.

[0023] According to another aspect of the present invention, a thermal straightening fixture is provided, which is applicable to the additive manufacturing method for complex titanium alloy shell structures as described above. The thermal straightening fixture includes a central body and a plurality of sub-body parts, which are evenly distributed around the central body and detachably connected to the central body. The dimensions of the central body are adjustable to accommodate product deformation.

[0024] This invention provides an additive manufacturing method and thermal forming tooling for complex titanium alloy shell structures. This method establishes a comprehensive additive manufacturing process scheme for complex titanium alloy shell structures with minimal support and thermal forming capabilities. It combines additive manufacturing with thermal forming, avoiding the need for complex support control required by relying solely on additive manufacturing, and also avoiding multiple sets of tooling and repeated thermal forming processes relying solely on thermal forming technology. The dimensions and structure of the thermal forming tooling surface, as well as the shell printing shape control requirements, were further designed. The shape control support structure was iteratively optimized through simulation, and based on this, forming printing, powder removal, and heat treatment were performed. This invention's technical solution is based on the consideration of high-quality, low-cost batch production, employing multi-technology integration to achieve high-quality, low-cost, and rapid additive manufacturing of products. Compared with existing technologies, this invention's technical solution can solve the technical problems of high cost and low product quality in existing additive manufacturing methods for complex titanium alloy shell structures. Attached Figure Description

[0025] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0026] Figure 1 A schematic diagram of a complex titanium alloy shell structure according to a specific embodiment of the present invention is shown;

[0027] Figure 2It shows along Figure 1 Schematic diagram of the cross section of the middle BB line;

[0028] Figure 3 A schematic diagram of the structure of the thermal straightening fixture provided according to a specific embodiment of the present invention is shown;

[0029] Figure 4 A top view of a thermal alignment fixture provided according to a specific embodiment of the present invention is shown;

[0030] Figure 5 A front view of a thermal alignment fixture provided according to a specific embodiment of the present invention is shown.

[0031] The above figures include the following reference numerals:

[0032] 1. Central body; 2. Components. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. 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 a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0036] like Figures 1 to 5 As shown, according to a specific embodiment of the present invention, an additive manufacturing method for complex titanium alloy shell structures is provided, the method comprising:

[0037] (1) Based on the characteristics of complex titanium alloy shell structures, a multi-technology integration approach was adopted to develop an overall additive manufacturing process scheme for complex titanium alloy shell structures with minimal support and thermal straightening.

[0038] (2) Based on the overall additive manufacturing process scheme, combined with the material parameters of the complex titanium alloy shell and the thermal straightening tooling, the dimensions of the thermal straightening tooling surface and the shell printing shape control requirements are obtained;

[0039] (3) Based on the dimensions of the hot-forming tooling surface and the complex titanium alloy shell structure, design the structure of the hot-forming tooling;

[0040] (4) Based on the overall additive manufacturing process scheme and combined with the complex titanium alloy shell structure, a preliminary shape control support structure is designed; the shape control support structure is optimized by simulation iteration, and a shell model with shape control support is obtained in combination with the shell printing shape control requirements;

[0041] (5) Use laser selective melting forming equipment to print a shell blank with shape control support;

[0042] (6) Clean the shell blank;

[0043] (7) Apply solder resist to the inner surface of the shell blank after powder removal, install the heat-correcting fixture into the shell blank, and perform heat treatment to achieve heat correction.

[0044] (8) Separate the shell blank from the substrate, remove the shape control support on the outside of the shell blank, grind the outer surface of the shell, and obtain a complex titanium alloy shell blank.

[0045] This configuration provides an additive manufacturing method for complex titanium alloy shell structures. The method establishes a comprehensive additive manufacturing process scheme for complex titanium alloy shell structures with minimal support and thermal shaping. It further designs the dimensions and structure of the thermal shaping tooling surface, as well as the shell printing shape control requirements. The shape control support structure is iteratively optimized through simulation, and based on this, forming printing, powder removal, and heat treatment are performed. The technical solution of this invention is based on the consideration of high quality and low cost in batch production, employing the integration of multiple technologies to achieve high-quality, low-cost, and rapid additive manufacturing of products.

[0046] like Figures 1 to 2 As shown, the additive manufacturing method of the present invention is aimed at complex titanium alloy shell structures. Typically, one end of the titanium alloy shell is a spherical end cap structure, and the remaining section is a cylindrical body with a wall thickness of 2.5mm. Multiple square window openings and boss structures are evenly distributed on the outer cylindrical surface.

[0047] For the complex titanium alloy shell structure mentioned above, the first step (1) is to implement the following: Based on the characteristics of the complex titanium alloy shell structure and considering the idea of ​​high quality and low cost in batch production, multiple technologies are integrated to formulate an overall additive manufacturing process scheme of less support printing and thermal correction to ensure that the cylinder size meets the technical requirements.

[0048] Among them, multi-technology integration refers to the integration of technologies such as additive manufacturing, heat treatment, and thermal expansion of materials in terms of physical properties.

[0049] The overall additive manufacturing process includes: adopting a low-support printing method, allowing the deformation of the cylinder to be slightly greater than the design specifications, reducing the amount of shape control supports, and lowering the difficulty of product printing; and then controlling the deformation of the cylinder within the design specifications through post-processing thermal correction.

[0050] Furthermore, in this invention, step (2) is performed: based on the material thermal expansion coefficient of the complex titanium alloy shell and the thermal correction tooling, the dimensions of the thermal correction tooling surface and the shell printing shape control requirements are obtained for the overall process scheme obtained in step (1).

[0051] Among them, the complex titanium alloy shell is usually made of TA15 titanium alloy, and the hot-forming tooling is usually made of stainless steel.

[0052] The diameter of the inner surface of the shell cylinder at high temperature is based on D t = a×(tT)×D T +D T Obtain, where D t D is the diameter of the inner surface of the shell cylinder at high temperature, a is the coefficient of linear expansion of the shell material, t is the high-temperature state temperature, T is the room temperature state temperature, and D is the diameter of the inner surface of the shell cylinder at high temperature. T This is the diameter of the inner surface of the shell cylinder at room temperature.

[0053] The outer diameter of the high-temperature heat-correcting fixture is consistent with the inner diameter of the shell cylinder under high temperature.

[0054] The outer diameter of the heat-forming fixture at room temperature is based on D' T =D' t / (a'×(tT)+1) is obtained, where D' T D' is the diameter of the outer circle of the heat-forming fixture at room temperature. t denoted as the outer diameter of the high-temperature heat-forming fixture, a' as the coefficient of linear expansion of the heat-forming fixture material, t as the high-temperature state temperature, and T as the room-temperature state temperature.

[0055] The shell printing shape control requirements can be obtained by comparing the outer diameter of the hot-calibration tooling with the inner diameter of the shell cylinder at room temperature.

[0056] Furthermore, in this invention, step (3) is performed: based on the dimensions of the thermal straightening tooling surface obtained in step (2), and based on the structural features of the complex titanium alloy shell cylinder with square window, the thermal straightening tooling is designed as a split structure, which is convenient for installation and disassembly, and also convenient for adapting to the actual deformation of the shell.

[0057] As a specific embodiment of the present invention, a thermal straightening fixture can be designed including a central body and multiple sub-body parts. The multiple sub-body parts are evenly distributed around the central body and are detachably connected to the central body. The structure of the outer side of the sub-body parts is adapted to the structure of the inner surface of the shell cylinder.

[0058] Furthermore, in this invention, step (4) is performed: based on the complex shell structure characteristics of titanium alloy, a preliminary shape control support structure is designed for the overall process scheme obtained in step (1). The shape control support structure is then optimized by simulation using software. Under the condition that the shell printing shape control requirements obtained in step (2) are met, the shell model with shape control support is obtained by using the minimum shape control support structure.

[0059] Simufact Additive can be used to perform simulation iteration optimization of the shape control support structure.

[0060] After iterative optimization, this invention adopts a V-shaped thin plate shape control support structure attached to the outer surface of a complex titanium alloy shell.

[0061] Further, in this invention, step (5) is performed: the shell model obtained in step (4) is sliced ​​using a large layer thickness parameter to obtain a printing package, and TA15 titanium alloy powder is used to print the shell in a laser selective melting forming equipment to obtain a deposited shell blank with a shape control support structure grown on a titanium alloy substrate.

[0062] Furthermore, in this invention, step (6) is performed: the printed shell blank obtained in step (5) is cleaned of residual powder to clean the inner cavity of the product head and the support structure, so as to avoid heat treatment caking.

[0063] Further, in this invention, step (7) is performed: The shell blank obtained in step (6) after removing residual powder is coated with solder resist on the inner surface of the shell, and a heat-forming fixture is installed (the surface of the heat-forming fixture can also be coated with solder resist). The heat-forming fixture undergoes vacuum heat treatment along with the shell blank, the product is annealed to relieve stress, and its mechanical properties are adjusted. The high coefficient of thermal expansion of the heat-forming fixture material is used to heat-form the complex inner wall of the shell at high temperature. This invention ensures that the shell dimensional tolerance is no greater than ±0.5mm. After vacuum heat treatment, the heat-forming fixture on the outside of the shell is removed after cooling.

[0064] Further, in this invention, step (8) is performed: the heat-treated shell blank obtained in step (7) is separated from the substrate by electrical discharge wire cutting, and then the shape control support supporting the shell blank is removed by manual operation by a fitter, and the outer surface of the shell is ground and the dimensions are measured and inspected to obtain a complex titanium alloy shell blank.

[0065] According to another aspect of the present invention, a thermal shaping fixture is provided, which is applicable to the additive manufacturing method for complex titanium alloy shell structures as described above. The thermal shaping fixture includes a central body and a plurality of sub-body parts, which are evenly distributed around the central body and detachably connected to the central body. The size and specifications of the central body can be adjusted to accommodate product deformation.

[0066] The structure on the outer side of the split body is adapted to the structure of the inner surface of the shell cylinder.

[0067] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0068] (1) The laser selective melting forming process of the present invention can be used to prepare titanium alloy shell blanks, and the products can be delivered in 45 days. This avoids the problems of high cost and long cycle of traditional casting process. At the same time, it can respond quickly and agilely to structural changes in the design department.

[0069] (2) Based on the characteristics of the complex shell structure of titanium alloy, and considering the idea of ​​high quality and low cost in batch production, the present invention has formulated an overall process scheme of less support printing forming + hot straightening to ensure that the cylinder size meets the technical requirements.

[0070] (3) This invention designs a split-type thermal correction fixture based on the difference in thermal expansion coefficients of different materials. The product is installed in the fixture before annealing and undergoes thermal correction during annealing. The fixture ensures the consistency of product dimensions without changing the product process route.

[0071] (4) This invention adopts a low-support printing process, which reduces the amount of shape control support powder by 35%, printing time by 21%, and manufacturing cost savings of 17%. The printing process allows for a cylinder deformation of ±1.2mm, and the cylinder deformation is controlled within ±0.5mm through post-processing thermal correction, thus meeting the design requirements.

[0072] (5) This invention can be extended to other similar products. Even under the premise of comprehensively considering the heat treatment cost, the cost of printing powder raw materials and machine time, the product can be printed without adding shape control support, allowing the product to deform freely during printing. In the post-processing stage, multiple thermal correction operations are performed to adjust the size to meet the delivery requirements.

[0073] To gain a further understanding of the present invention, the additive manufacturing method for complex titanium alloy shell structures of the present invention will be described in detail below with reference to specific embodiments.

[0074] like Figures 1 to 5 As shown in the figure, an additive manufacturing method for complex titanium alloy shell structures is provided according to a specific embodiment of the present invention, which specifically includes the following steps.

[0075] Step (1): Based on the characteristics of the complex shell structure of titanium alloy and considering the idea of ​​high quality and low cost in batch production, a multi-technology integration was adopted to formulate an overall process plan of less support printing forming + thermal correction to ensure that the cylinder size meets the technical requirements.

[0076] Step (2): Based on the overall process scheme obtained in step (1), and the thermal expansion coefficient of the titanium alloy complex shell and the thermal correction tooling, obtain the dimensions of the thermal correction tooling surface and the shell printing shape control requirements.

[0077] In this embodiment, the inner diameter D of the shell cylinder at room temperature T 385mm.

[0078] The diameter of the inner surface of the shell cylinder at high temperature is obtained based on the tooling dimension calculation parameters in Table 1:

[0079] Table 1 Tooling Dimension Calculation Parameters

[0080]

[0081]

[0082] Diameter of the inner surface of the shell / cylinder at high temperature:

[0083] D t =10.9×10 -6 ×(800-25)×385+385=388.25mm.

[0084] The outer diameter of the high-temperature heat-forming fixture is consistent with the inner diameter of the shell / cylinder, D' t =D t = 388.25mm.

[0085] Outer diameter of the heat-setting fixture at room temperature:

[0086] D' T =388.25÷(19.0×10 -6 ×(800-25)+1)=382.6mm.

[0087] The clearance between the thermal straightening fixture and the inner surface of the shell / cylinder at room temperature is:

[0088] (385-382.6)÷2=1.2mm,

[0089] Therefore, the required shape control for shell printing is ±1.2mm.

[0090] Step (3): Based on the dimensions of the thermal straightening tooling surface obtained in step (2), and based on the structural features of the complex titanium alloy shell cylinder with square window, the thermal straightening tooling is designed as a split structure, which is convenient for installation and disassembly, and also convenient for adapting to the actual deformation of the shell.

[0091] like Figures 3 to 5 As shown, in this embodiment, the thermal straightening fixture includes a central body 1 and four sub-body 2. The four sub-body 2 are evenly distributed around the central body 1 and are detachably connected to the central body 1.

[0092] Step (4): Based on the complex shell structure characteristics of titanium alloy, the overall process scheme obtained in step (1) is initially designed with a shape control support structure. SimufactAdditive is used to simulate and iteratively optimize the shape control structure. The minimum shape control support is used to ensure that the shape control is within ±1.2mm. After optimization, a V-shaped thin plate shape control structure is attached to the outer surface of the cylinder with a weight of 4kg to obtain a shell model with shape control support.

[0093] Step (5): The shell model obtained in step (4) is sliced ​​using a large layer thickness parameter of 0.1 mm to obtain a printing program package. TA15 titanium alloy powder with a specification of 20-75 μm is used to print the shell model in a laser selective melting forming equipment to obtain a deposited shell blank with a controlled shape structure grown on a titanium alloy substrate.

[0094] Step (6): Perform a powder cleaning operation on the printed shell blank obtained in step (5) to clean the residual powder in the inner cavity of the product head and the support structure to avoid heat treatment caking.

[0095] Step (7): Apply solder resist to the inner circumference of the shell blank obtained in step (6) after removing residual powder, and install it into a heat-forming fixture (the surface of the fixture is coated with solder resist). The fixture is then subjected to vacuum heat treatment along with the shell blank. In this embodiment, the vacuum heat treatment regime is: 800±10℃, holding for 2 hours, and furnace cooling.

[0096] The product undergoes stress relief annealing and mechanical property adjustment. Utilizing the high expansion coefficient of stainless steel, it is thermally shaped at high temperatures by bonding with the inner wall of the cylinder, ensuring the cylinder's dimensional tolerance is no greater than ±0.5mm. After vacuum heat treatment and cooling, the cylinder's thermal shaping fixture is removed.

[0097] Step (8): The heat-treated shell blank obtained in step (7) is separated from the substrate by electrical discharge wire cutting. Then, the shape control support supporting the shell blank is removed by manual operation by a fitter, and the outer surface of the shell is ground. The dimensions are measured and inspected to obtain a complex titanium alloy shell blank.

[0098] In summary, this invention provides an additive manufacturing method and thermal shaping tooling for complex titanium alloy shell structures. This method establishes a comprehensive additive manufacturing process scheme for complex titanium alloy shell structures with minimal support and thermal shaping. It further designs the dimensions and structure of the thermal shaping tooling surface, as well as the shell printing shape control requirements. The shape control support structure is iteratively optimized through simulation, and based on this, forming printing, powder removal, and heat treatment are performed. The technical solution of this invention is based on the consideration of high-quality, low-cost batch production, and adopts the integration of multiple technologies to achieve high-quality, low-cost, and rapid additive manufacturing of products.

[0099] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An additive manufacturing method for complex titanium alloy shell structures, characterized in that, The additive manufacturing method for complex titanium alloy shell structures includes: (1) Based on the characteristics of complex titanium alloy shell structures, a multi-technology integration approach was adopted to develop an overall additive manufacturing process scheme for complex titanium alloy shell structures with minimal support and thermal straightening. (2) Based on the overall additive manufacturing process scheme, combined with the material parameters of the complex titanium alloy shell and the thermal straightening tooling, the dimensions of the thermal straightening tooling surface and the shell printing shape control requirements are obtained; (3) Based on the dimensions of the hot-forming tooling surface and the complex titanium alloy shell structure, design the structure of the hot-forming tooling; (4) Based on the overall additive manufacturing process scheme and combined with the complex titanium alloy shell structure, a preliminary shape control support structure is designed; the shape control support structure is optimized by simulation iteration, and a shell model with shape control support is obtained in combination with the shell printing shape control requirements; (5) Use laser selective melting forming equipment to print a shell blank with shape control support; (6) Clean the shell blank; (7) Apply solder resist to the inner surface of the shell blank after powder removal, install the heat-correcting fixture into the shell blank, and perform heat treatment to achieve heat correction. (8) Separate the shell blank from the substrate, remove the shape control support on the outside of the shell blank, grind the outer surface of the shell, and obtain a complex titanium alloy shell blank.

2. The additive manufacturing method for complex titanium alloy shell structures according to claim 1, characterized in that, The complex titanium alloy shell is made of TA15 titanium alloy, and the hot-forming tooling is made of stainless steel.

3. The additive manufacturing method for complex titanium alloy shell structures according to claim 1, characterized in that, In step (2), the shell printing shape control requirements are obtained based on the difference between the outer diameter of the thermal calibration fixture at room temperature and the inner diameter of the shell cylinder; the outer diameter of the thermal calibration fixture at room temperature is based on D' T =D' t / (a'×(tT)+1) is obtained, where D' T D' is the diameter of the outer circle of the heat-forming fixture at room temperature. t denoted as the outer diameter of the high-temperature heat-forming fixture, a' as the coefficient of linear expansion of the heat-forming fixture material, t as the high-temperature state temperature, and T as the room-temperature state temperature.

4. The additive manufacturing method for complex titanium alloy shell structures according to claim 3, characterized in that, High-temperature heat-correction tooling outer diameter D' t To match the inner diameter D of the shell cylinder at high temperatures t Consistent, D t = a×(tT)×D T +D T Where a is the coefficient of linear expansion of the shell material, and D T This is the diameter of the inner surface of the shell cylinder at room temperature.

5. The additive manufacturing method for complex titanium alloy shell structures according to claim 1, characterized in that, The thermal alignment fixture includes a central body and multiple sub-body parts. The sub-body parts are evenly distributed around the central body and are detachably connected to the central body. The structure on the outside of the sub-body parts is adapted to the structure of the inner surface of the shell cylinder.

6. The additive manufacturing method for complex titanium alloy shell structures according to claim 1, characterized in that, In step (4), SimufactAdditive is used to perform simulation iteration optimization of the shape control support structure.

7. The additive manufacturing method for complex titanium alloy shell structures according to claim 6, characterized in that, After iterative optimization, a V-shaped thin plate shape control support structure is adopted and attached to the outer surface of the complex titanium alloy shell.

8. The additive manufacturing method for complex titanium alloy shell structures according to claim 1, characterized in that, In step (5), the shell model obtained in step (4) is sliced ​​using a large layer thickness parameter to obtain a printing package. TA15 titanium alloy powder is used to print the shell in a laser selective melting forming equipment to obtain a deposited shell blank with a shape control support structure grown on a titanium alloy substrate.

9. The additive manufacturing method for complex titanium alloy shell structures according to claim 1, characterized in that, In step (7), the hot-forming tooling is vacuum heat-treated along with the shell blank, the product is annealed to relieve stress, and the mechanical properties are adjusted. The high expansion coefficient of the hot-forming tooling material is used to fit the complex inner wall of the shell at high temperature for hot-forming. The shell size tolerance is no more than ±0.5mm.

10. A heat-adjusting tooling, characterized in that, The thermal forming fixture is applicable to the additive manufacturing method for complex titanium alloy shell structures as described above. The thermal forming fixture includes a central body and multiple sub-body parts, which are evenly distributed around the central body and detachably connected to it. The size of the central body is adjustable to accommodate product deformation.

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