A conformal machining design method suitable for thick-section titanium alloy blisk forgings

Abstract

The present application belongs to the field of titanium-based alloys, and particularly relates to a conformal machining design method suitable for thick-section titanium alloy integral blade disc forgings, which comprises applicable alloy types, blade disc feature structure forms and size design and other constituent elements. The conformal machining design method is suitable for TC25G, TA33, TA37, TA38 and other titanium alloy thick-section integral blade disc forgings, can maximize the retention of key performance such as strength, and ensures that the mechanical properties of the thick-section forgings meet the design requirements. The patent technology can be used for conformal machining design of large-size thick-section integral blade disc forgings with an integral or local thickness of more than 100 mm, and meets the application requirements of advanced aero-engines for large-size thick-section integral blade disc forgings.

Description

Technical Field

[0001] This invention belongs to the field of titanium-based material processing and manufacturing, and specifically relates to a conformal machining design method suitable for thick-section titanium alloy integral bladed disk forgings. Background Technology

[0002] Titanium alloys possess advantages such as high specific strength, corrosion resistance, and heat resistance, making them widely used in aerospace, petroleum, chemical, energy, automotive, medical, and sports and leisure industries. With the development of aerospace technology, the demand for titanium alloys, especially high-temperature titanium alloys, is gradually expanding, and the technical requirements are also gradually increasing, such as requiring higher temperature resistance, higher strength, and good processability.

[0003] Integrated structural design is a new design concept proposed in recent years, with the main purpose of reducing the number of parts and improving structural efficiency. Structural integration implies increased part size and structural complexity, leading to a significant increase in manufacturing difficulty. Therefore, integrated structural design requires the support of advanced materials and process technologies.

[0004] In recent years, advanced aero-engines have generated a strong demand for high-temperature, large-size integral bladed disk forgings. For example, the diameter of a traditional titanium alloy integral bladed disk is approximately 700mm, while newer engines require an integral bladed disk diameter of ≥1100mm. This has increased the weight of the required forging blank from ≥200kg to ≥400kg, and the thickness from ≤80mm to over 100mm. Simultaneously, from the perspective of weight reduction and minimizing the number of parts, it is necessary to adopt an integral disk-drum structure whenever possible. The characteristic of the integral disk-drum structure is that the disk and drum are formed as a single unit without mechanical connection. It can be manufactured using direct die forging followed by CNC machining, significantly simplifying the process and reducing the number of parts. However, because the disk and drum are manufactured together, the dimensions of the forging, especially in the thickness direction, increase significantly. Depending on the structural form, such as a single-sided or double-sided drum, the thickest part of the integral bladed disk ranges from 140mm to 500mm, increasing the requirements for raw material quality and posing significant challenges to the uniformity of the microstructure and performance control of different locations within the forging. Summary of the Invention

[0005] The purpose of this invention is to provide a conformal machining design method for thick-section titanium alloy integral bladed disk forgings. The technical principle is applicable to high-temperature titanium alloy materials such as TC25G, TA32, TA33, TA37, and TA38.

[0006] A conformal machining design method is applicable to thick-section titanium alloy integral bladed disk forgings. The conformal machining design method is applicable to high-temperature titanium alloy materials such as TC25G, TA33, TA37, and TA38. Its feature is that it is applicable to the preparation of integral bladed disk forgings for aero-engines, and its mechanical properties are sensitive to the cooling rate after heat treatment.

[0007] The preferred embodiment of the conformal machining design method for thick-section titanium alloy integral bladed disk forgings is as follows: the preparation process route of the conformal machining forging is: billet preparation → die forging and air cooling → rough machining → ultrasonic flaw detection → conformal machining → heat treatment → finish machining.

[0008] The preferred embodiment of the conformal machining design method for thick-section titanium alloy integral bladed disk forgings is as follows:

[0009] Step 1: First, design the forging blank drawing based on the part drawing, and give the longitudinal section dimensions of the forging blank;

[0010] Step 2: Determine the thickness of different areas of the forging blank, such as blades, rims, spokes, and hubs;

[0011] Step 3: Design the conformal machining of the integral bladed disk forging blank. Based on the part drawing, add a single-sided allowance for the conformal machining part, and give the initial sample drawing of conformal machining accordingly.

[0012] Step 4: If the conformal machining part includes blades, the conformal machining dimension design of the blade part must meet the constraint condition 2π(r+15~25) / n+δ≥40mm, where r is the blade root radius, n is the number of blades, and δ is the maximum thickness of the blade.

[0013] Step 5: The leaf base and underside allowances are designed asymmetrically;

[0014] Step Six: The transition zone includes the hub-spoke transition, spoke-blade transition, and rim-drum connection area, etc., and the dimensions of the transition zone are optimized.

[0015] Step 7: Based on the aforementioned steps 1 to 6, provide the final design scheme for conformal machining.

[0016] The preferred embodiment of the conformal machining design method for thick-section titanium alloy integral bladed disk forging is as follows: in step three, the minimum dimension in different directions of any part or position of the conformal machining forging is set as the thickness, and a allowance of ≥13mm is left on one side according to the dimensions of the part drawing.

[0017] The preferred embodiment of the conformal machining design method for thick-section titanium alloy integral bladed disk forgings is as follows: in step two, the portion with a size exceeding 100mm is defined as the conformal machining area; and this conformal machining design method is applicable to integral bladed disk forgings with an overall or partial thickness ≥100mm.

[0018] The preferred embodiment of the conformal machining design method for thick-section titanium alloy integral bladed disk forging is as follows: in step five, the allowances left for the blade base and blade back are different, with the blade back having a machining allowance of 1mm to 4mm more than that for the blade base.

[0019] The preferred embodiment of the conformal machining design method for thick-section titanium alloy integral bladed disk forgings is that, in step six, the feature dimension at any position of the conformal machining forging is ≤100mm.

[0020] The advantages and beneficial effects of this invention are:

[0021] This application addresses the design and application requirements of large-size, high-temperature titanium alloy bladed disks and their integrated structures in advanced aero-engines, proposing a conformal machining design method suitable for thick-section titanium alloy integral bladed disk forgings. The basic idea is to first process the forging blank (with attached...) Figure 1 (Attached) Figure 2 The process involves removing excess material to bring the local dimensions of large, thick-section forgings to a level comparable to traditional small-sized forgings before heat treatment. However, the shape of forgings produced by conformal machining is very complex, with stress concentrations, thin walls, and localized suspended areas. It is necessary to comprehensively consider the potential dimensional inconsistencies and stress cracking problems that may arise during subsequent high-temperature heat treatment. Therefore, creative design of the shape and dimensions of conformal machining is required to fully utilize its advantages and minimize its associated problems.

[0022] The conformal machining design method of the present invention can bring the following beneficial effects and conveniences:

[0023] 1. The dimensional constraints of integral bladed disk parts design and fabrication are significantly reduced, providing a technical basis for the design and application of large-size, thick, high-performance integral bladed disk forgings;

[0024] 2. The design method is relatively simple and easy to operate;

[0025] 3. It will promote the emergence of a series of new technologies (such as ultra-large size forging preparation technology), new methods (such as the conformal machining forging design method described in this application), and new standards (such as the inspection and acceptance standards for conformal machining forgings), which will be beneficial to the technological progress of the industry. Attached Figure Description

[0026] Appendix Figure 1 Schematic diagram of a traditional integral bladed disk forging blank;

[0027] Appendix Figure 2 Schematic diagram of conformal forging;

[0028] Appendix Figure 3 Schematic diagram of blade conformal machining location design;

[0029] Appendix Figure 4 Schematic diagram of asymmetrical design of leaf base and leaf back in conformal machining;

[0030] Appendix Figure 5 Example 1 of this application shows the hardness variation curve of the forging from the surface to the core;

[0031] Appendix Figure 6 Creep curve of the forging near 1000°C in Example 2 of this application;

[0032] Appendix Figure 7 Example of conformal machining in Embodiment 3 of this application;

[0033] Appendix Figure 8 Example 4 of this application is a conformal machining example. Detailed Implementation

[0034] This invention provides a conformal machining design method for thick-section titanium alloy integral bladed disk forgings, including applicable materials, characteristic structural forms and dimensional design principles, and methods. Specifically, it includes the following steps:

[0035] 1) Based on the shape and dimensions of the target part, design and provide a forging blank drawing;

[0036] 2) Based on the forging blank drawing, determine the conformal machining parts based on whether the characteristic thickness of the forging is ≥100mm;

[0037] 3) Based on the dimensions of the target part, and taking into account the minimum allowance of no less than 13mm on one side of the part's conformal machining area (generally the thickness direction), an initial sample drawing is produced.

[0038] 4) Optimize the design of the initial sample: 1) For conformal blades, the radius r at the blade root, the number of blades n, and the maximum thickness δ of the blades shall be subject to the constraint condition 2π(r+15~25) / n+δ≥40; 2) The blade base and blade back shall adopt an asymmetric allowance design, with the blade back having a machining allowance of 1~4mm more than the blade base; 3) The feature dimensions of the remaining parts of the overall bladed disk shall be controlled within 100mm.

[0039] 5) Determine the final conformal machining scheme and drawings.

[0040] The characteristics of the above design method are: 1) combining the size effect of material mechanical properties with structural design methods to better realize the performance and function of structural components; 2) comprehensively considering the cold and hot working of structural components and reflecting it in the structural design. Currently, the cold and hot working of titanium alloy parts are completely separate. The process before heat treatment of forgings is considered hot working, while the subsequent turning is considered cold working. This application sets some roughing processes, which belong to traditional cold working, before the heat treatment of forgings, organically integrating cold and hot working, so that ultra-large size and ultra-thickness forgings can not only be manufactured, but also the function and performance of materials can be maximized.

[0041] The present invention will be further described in detail below through embodiments.

[0042] Example 1

[0043] The experimental material was a 120mm thick heat-treated integral bladed disk forging. Specimens were taken along the longitudinal section, and hardening was performed radially from the outer surface towards the center at half the thickness. The HRC curve as a function of distance from the surface is shown in the appendix. Figure 5 It can be seen that the HRC of heat-treated forgings shows a trend of first decreasing and then flattening from the surface to the core. There is a region of sharp hardness change at a distance of 13mm from the outer surface. To avoid this region, when designing the blank drawing of conformal machining forgings, the machining allowance on one side of the conformal machining blank should not be less than 13mm.

[0044] Example 2

[0045] The experimental material was a 120mm thick heat-treated integral bladed disk forging. Chordular specimens were taken near 1 / 2 thickness and 1 / 2R. Creep deformation over time was measured within the temperature range of 980℃ to 1030℃. (See attached figure.) Figure 6 It is evident that under high-temperature conditions near 1000℃, even under low stress of 2–5 MPa, significant creep deformation will occur. To avoid dimensional deviations due to high-temperature creep deformation during high-temperature heat treatment, approximately 2% creep deformation is considered in the conformal machining design, corresponding to a deformation of 1–4 mm.

[0046] Example 3

[0047] The integral bladed disk component comprises three parts: hub, spokes, and blades. The disk diameter is 1070mm, hub thickness is 42mm, spoke thickness is 12mm, blade width is 94mm, blade length is 138mm, and blade thickness ranges from 1.0 to 2.2mm. There are 42 blades. The forged blank dimensions are: disk diameter 1100mm, hub and spoke thickness 52mm, and blade thickness 110mm. The conformal machining part is the blade body.

[0048] Conformal machining scheme: 1) The hub and spokes are left unmachined, maintaining the initial thickness of the forging blank at 52mm; 2) The blade portion is expanded 20mm outward from the blade root, with a designed machining allowance of 14mm at the blade head and 17mm at the blade back. 2π(r+15~25) / n+δ=74.8mm. The characteristic dimensions of different parts of the conformal-machined forging blank are controlled within 54mm. See attached example. Figure 7 .

[0049] Example 4

[0050] The integral bladed disk component comprises four parts: hub, spokes, drum, and blades. The bladed disk has a diameter of 1120mm, a hub thickness of 40mm, and spoke thickness of 16mm. The left drum height is 148mm, the right drum height is 174mm, and the drum wall thickness is 3.2mm. The blades are 108mm wide, 340mm long, and 1.2-2.6mm thick, with a quantity of 24 blades. The designed forging blank dimensions are: bladed disk diameter of 1160mm, hub and spoke thickness of 60mm, and blade thickness of 130mm. The conformal machining parts are the integral bladed disk drum and blade.

[0051] Conformal machining solution: see appendix Figure 8 Example. The outermost solid line in the figure is the forging blank drawing, the middle dashed line is the conformal machining drawing, and the innermost part is the part drawing. Specifically: 1) The hub and spokes are not conformally machined, retaining the original blank thickness of 60mm; 2) A 20mm allowance is left on the outer surface of the drum, and a 35mm allowance is left on the inner surface (15mm allowance is left relative to the inner side of the mounting edge). The dimension of this area after conformal machining is controlled between 58 and 60mm; 3) A 20mm machining allowance is left at the blade root (same as in Example 3). The machining allowances on the blade base and blade back are designed asymmetrically, with a 14mm machining allowance on the blade base and an 18mm machining allowance on the blade back. The thickness of a single conformally machined blade is 33.2 to 34.6mm, 2π(r+15~25) / n+δ=107mm; Other parts, such as the transition between the blade and the drum, have a ≥20mm allowance, and the conformal machining feature dimensions are controlled between 30 and 80mm.

[0052] In summary, increasing component size and integrating structural design are among the future directions for optimizing aircraft and engine component design. Conformal machining is a necessary means to address the application of low thermal conductivity materials in thick-section forgings. This invention proposes a conformal machining design method suitable for thick-section titanium alloy integral bladed disk forgings, from the perspective of design and application of large-size integral bladed disk forgings made of high-temperature titanium alloys. Using this method, the core strength of the forging can be significantly improved, thereby meeting the strength design requirements of the component. The technical means of this application will strongly promote the technological development of large-size, thick-section components, further drive the expanded application of high-temperature titanium alloy materials such as TA33, TA37, and TA38 in aero-engines, and also have broad prospects for application in other models and structures.

Claims

1. A conformal machining design method for thick-section titanium alloy integral bladed disk forgings, characterized in that: The conformal machining design method is applicable to high-temperature titanium alloy materials such as TC25G, TA33, TA37, and TA38. These high-temperature titanium alloy materials are suitable for the preparation of integral bladed disk forgings for aero-engines, and their mechanical properties are sensitive to the cooling rate after heat treatment. The preparation process route of the conformal forging is as follows: billet preparation → die forging and air cooling → rough machining → ultrasonic flaw detection → conformal machining → heat treatment → finish machining; The design process is as follows: Step 1: First, design the forging blank drawing based on the part drawing, and give the longitudinal section dimensions of the forging blank; Step 2: Determine the thickness of different parts of the forging blank, including the blade, rim, spokes, and hub; Step 3: Design the conformal machining of the integral bladed disk forging blank. Based on the part drawing, add a single-sided allowance for the conformal machining part, and give the initial sample drawing of conformal machining accordingly. Step 4: The conformal machining dimensions of the blade section must meet the following requirements. The constraint conditions are given by the formula, where r is the root radius of the leaf, n is the number of leaves, and δ is the maximum thickness of the leaf. Step 5: The leaf base and underside allowances are designed asymmetrically; Step Six: Optimize the dimensions of the transition zone; the transition zone includes the hub-spoke transition, the spoke-blade transition, and the rim-drum transition; Step 7: Based on the aforementioned steps 1 to 6, provide the final design scheme for conformal machining.

2. The conformal machining design method for thick-section titanium alloy integral bladed disk forgings according to claim 1, characterized in that: In step three, the minimum dimension of any part or position of the conformal forging in different directions is set as the thickness, and a margin of ≥13mm is designed according to the dimensions of the part drawing on one side.

3. The conformal machining design method for thick-section titanium alloy integral bladed disk forgings according to claim 1, characterized in that: In step two, the portion with a size exceeding 100mm is defined as the conformal machining area; and this conformal machining design method is applicable to integral bladed disk forgings with an overall or partial thickness ≥100mm.

4. The conformal machining design method for thick-section titanium alloy integral bladed disk forgings according to claim 1, characterized in that: In step five, the allowances left for the leaf base and the leaf back are different, with the leaf back having 1mm to 4mm more processing allowance than the leaf base.

5. The conformal machining design method for thick-section titanium alloy integral bladed disk forgings according to claim 1, characterized in that: In step six, ensure that the feature dimension at any position of the conformally machined forging is ≤100mm.

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