Die for forming titanium alloy leading edge of composite fan blades for aero-engines

Abstract

This invention relates to a titanium alloy leading edge forming mold for composite fan blades of aero-engines. The mold is used for diffusion bonding forming of a first preform (4) and a second preform (5). It includes a lower mold (2) for assembling the second preform (5), a core mold (3) for placing between the first preform (4) and the second preform (5), and an upper mold (1) for pressing on top of the first preform (4). Each of the first preform (4), the second preform (5), and the core mold (3) has an ear piece (7) at its end. This ear piece (7) extends out of the mold when the upper mold (1) and the lower mold (2) are closed. The ear pieces (7) of the first preform (4), the second preform (5), and the core mold (3) are fixed by pins (6). Compared with the prior art, this invention has advantages such as convenient processing and high precision.

Description

Technical Field

[0001] This invention relates to a forming mold, specifically to a forming mold for the titanium alloy leading edge of a composite fan blade for an aero-engine. Background Technology

[0002] To achieve a high thrust-to-weight ratio, aero-engines need to continuously improve their lightweighting capabilities. Composite materials, with their high specific strength, high specific stiffness, and good fatigue resistance, can effectively meet the lightweighting and fatigue resistance requirements of aero-engines. Therefore, the usage and proportion of composite materials in aero-engines are constantly increasing. Aero-engine blades are numerous and heavy, and their lightweighting can effectively meet the actual needs of future engine applications. The reliable and efficient processing of composite fan blades for aero-engines is receiving increasing attention.

[0003] Diffusion bonding technology involves bringing the surfaces to be joined into contact, heating them to a temperature below the melting point of the base material under vacuum or a protective gas atmosphere, and applying pressure. This causes microscopic plastic deformation of the surfaces, increasing the contact area. During subsequent heat and pressure holding, atoms on both sides of the joined surfaces diffuse over a certain period, achieving bonding. Compared to traditional welding techniques, diffusion bonding uses a lower heating temperature, typically 0.4 to 0.8 times the melting point of the base material, without adversely affecting the physicochemical properties of the base material. The mechanical properties of the joint are also superior to those of traditional welding. Since no macroscopic plastic deformation occurs in the joined materials, the dimensional accuracy of the joint is guaranteed. Currently, there are no molds specifically designed for diffusion bonding of the leading edge edge of titanium alloy composite fan blades for aero-engines. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a convenient and high-precision forming mold for the titanium alloy leading edge of aero-engine composite fan blades.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A titanium alloy leading edge forming mold for composite fan blades of aero-engines is characterized in that the mold is used for diffusion bonding forming of a first preform and a second preform, comprising a lower mold for assembling the second preform, a core mold for placing between the first and second preforms, and an upper mold for pressing on top of the first preform.

[0007] The first preform, the second preform, and the core mold are all provided with lugs at their ends. The lugs extend out of the mold when the upper and lower molds are closed. The lugs of the first preform, the second preform, and the core mold are fixed by pins.

[0008] Furthermore, the upper mold has a stepped through hole at the top corner, and the lower mold has a corresponding positioning through hole. The stepped through hole and the positioning through hole are connected by a pin.

[0009] Furthermore, the core mold has a step, and the lower mold has a groove that matches the step.

[0010] Furthermore, when the upper and lower molds are closed, a gap is left between the parting surfaces.

[0011] Furthermore, the mold also includes a spacer for filling the spacer.

[0012] Furthermore, the gasket is provided in multiple portions, and the multiple gaskets have different thicknesses.

[0013] Furthermore, when the upper and lower molds are closed, a prying opening structure is provided between the parting surfaces.

[0014] Furthermore, a notch is provided at at least one apex corner of the parting surface of the upper or lower mold to form the pry hole structure.

[0015] Furthermore, the core mold is provided with a threaded hole that allows the core mold to be unscrewed.

[0016] Furthermore, the pin is a stepped pin.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This invention uses an upper mold, a lower mold, and a core mold to perform diffusion connection forming on a first preform and a second preform to form a titanium alloy leading edge edging product for aero-engine composite fan blades. The upper and lower mold surfaces match the outer surface of the reinforcing edge to ensure the forming accuracy of the outer surface during the forming process. The outer surface of the core mold matches the inner cavity of the reinforcing edge to ensure the forming accuracy of the inner cavity during the forming process. This invention is easy to process and has high forming accuracy.

[0019] 2. The first and second preforms to be connected and the core mold all have lugs extending from both sides, which facilitates the positioning of the product and the mold and improves the reliability of processing; and the positioning lugs of the product and the core mold extend out of the mold and are not compressed during diffusion connection, thus preventing the pin from connecting to the product.

[0020] 3. This invention addresses the deformation of the product during diffusion bonding by designing the compression amount. After assembling the upper and lower molds with the product, a certain gap is left between the parting surfaces. A shim can be added to the gap to control the downward pressure of the mold. When pressure is applied, it ensures that there is a suitable amount of compression between the surfaces to be connected. At the same time, the compression amount of the connecting surfaces can be flexibly controlled to prevent the product from not being connected or from overflowing, thus ensuring the quality of the joint.

[0021] 4. The upper mold of this invention is provided with a stepped through hole at the top corner, and the lower mold is provided with a corresponding positioning through hole. The stepped through hole and the positioning through hole are connected by a pin, so that the mold can be closed reliably.

[0022] 5. The present invention uses stepped pins for positioning between the upper and lower molds and between the ear pieces. Compared with traditional pins, the use of stepped short pins to position the mold and the product makes the pins less prone to deformation and the positioning more accurate. At the same time, the short pins are also easier to demold.

[0023] 6. The present invention has a prying structure at the parting surface between the upper and lower molds, so that a wedge-shaped space is left after the upper and lower molds are closed, which makes it easy to pry open the mold.

[0024] 7. The core mold of the present invention is provided with a threaded hole through which the core mold can be unscrewed, so that the product and the core mold can be demolded through the thread, preventing the prying process from affecting the surface accuracy.

[0025] 8. The final forming accuracy of the parts of the present invention can be controlled within ±0.05mm. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the mold of the present invention;

[0027] Figure 2 This is a schematic diagram of the mold closing mechanism of the present invention;

[0028] Figure 3 This is a schematic diagram of mold positioning;

[0029] Figure 4 This is a schematic diagram of the upper mold;

[0030] Figure 5 This is a schematic diagram of the lower mold;

[0031] Figure 6 This is a schematic diagram showing the control of the downward pressure after mold closing;

[0032] Figure 7 This is a schematic diagram of the core mold;

[0033] In the diagram: 1. Upper mold, 2. Lower mold, 3. Core mold, 4. First preform, 5. Second preform, 6. Pin, 7. Ear piece, 8. Notch, 9. Washer, 10. Threaded hole. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment provides a titanium alloy leading edge forming mold for aero-engine composite fan blades. This mold is used for diffusion bonding forming of a first preform 4 and a second preform 5 to form a titanium alloy reinforcing edge at the leading edge of the composite fan blade. It includes a lower mold 2 for assembling the second preform 5, a core mold 3 for placing between the first preform 4 and the second preform 5, and an upper mold 1 for pressing on top of the first preform 4. The surfaces of the upper and lower molds match the outer surfaces of the reinforcing edge to ensure the forming accuracy of the outer surfaces during the forming process. The outer surface of the core mold matches the inner cavity of the reinforcing edge to ensure the forming accuracy of the inner cavity during the forming process. During forming, the entire mold is placed in a vacuum hot press furnace for heating, and pressure is applied by a press, causing diffusion bonding between the preforms to form the integral composite fan blade leading edge titanium alloy reinforcing edge.

[0041] The upper and lower preforms of the product are manufactured by machining to ensure the surface accuracy of the product before diffusion bonding. Combined with prototype prototyping and point cloud scanning technology, the dimensional accuracy of the product is guaranteed.

[0042] To address the issue of thermal expansion between the product and the mold, the spatial structure between the upper mold 1, lower mold 2, and core mold 3 is designed based on pre-calculated thermal expansion, preventing the product's thermal expansion from affecting the diffusion connection process and the final dimensional accuracy. Specifically, the thermal expansion is calculated through finite element simulation of the theoretical model, yielding the product's thermal deformation at high temperatures.

[0043] In a specific embodiment, the first preform 4, the second preform 5, and the core mold 3 are all provided with lugs 7 at their ends. These lugs 7 extend outside the mold when the upper mold 1 and lower mold 2 are closed. The lugs 7 of the first preform 4, the second preform 5, and the core mold 3 are fixed by pins 6. The pins 6 are stepped pins, and the lugs 7 have pin holes for the pins to pass through. After the upper mold 1 and lower mold 2 are assembled, the core mold 3 and the pin holes on the lugs 7 on both sides of the preform extend out of the mold and are in the same vertical position, controlling the relative position of the preform and the core mold 3, such as... Figure 2 As shown.

[0044] In specific implementations, such as Figure 4 and Figure 5 As shown, the upper mold 1 has a stepped through hole at its apex, divided into two sections of different diameters, larger at the top and smaller at the bottom. A step is formed between the two coaxial cylindrical holes. The lower mold 2 has a corresponding positioning through hole. The stepped through hole and the positioning through hole are connected by a pin 6. The pin 6 is a stepped pin. When the mold is closed, the pin is inserted into the stepped through hole. The lower part of the pin passes through both the upper and lower molds, while the upper part is engaged with the step in the stepped through hole, thus positioning the relative positions of the upper and lower molds. Figure 3 As shown.

[0045] In a specific embodiment, the core mold 3 is provided with a step, and the lower mold 2 is provided with a groove that matches the step. During assembly, the step is inserted into the groove to achieve the positioning of the core mold relative to the upper and lower molds.

[0046] In a preferred embodiment, after assembling the upper and lower molds with the product, a certain gap is left between the parting surfaces. A shim 9 can be added into the gap to control the downward pressure of the mold. Figure 6 As shown, when pressure is applied, a suitable amount of compression is ensured between the surfaces to be joined. Multiple gaskets 9 are provided, each with a different thickness, allowing for the addition of gaskets of varying thicknesses during processing as needed.

[0047] In a preferred embodiment, a pry-out structure is provided between the parting surfaces when the upper mold 1 and the lower mold 2 are closed. Specifically, in this embodiment, a portion is cut off at the four apex corners of the parting surface of the lower mold 2 to form notches 8, such as... Figure 5As shown, this leaves a wedge-shaped space after the upper and lower molds are closed, making it easier to pry open the mold.

[0048] In a preferred embodiment, the core mold 3 is provided with a threaded hole 10 through which the core mold 3 can be unscrewed, such as... Figure 7 As shown. Specifically, multiple threaded holes 10 are provided and distributed on the side of the core mold 3 to facilitate the removal of the core mold by screws and to prevent the prying process from affecting the surface accuracy.

[0049] In this embodiment, 310s stainless steel was used as the mold material and TC4 was used as the product material. The diffusion welding parameters were: temperature 900℃, pressure 2Mpa, and time 2h. The leading edge reinforcement edge of the engine composite blade was fabricated. The forming accuracy of the part was measured to be within ±0.02mm by point cloud scanning.

[0050] Example 2

[0051] refer to Figures 1-7 As shown in this embodiment, in the titanium alloy leading edge forming mold for aero-engine composite fan blades, a portion of the four apex corners of the parting surface of the lower mold 1 is cut off to form notches 8, leaving a wedge-shaped space after the upper and lower molds are closed, which facilitates prying open the mold. The rest is the same as in Embodiment 1.

[0052] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A die for forming the leading edge of a titanium alloy composite fan blade for an aero-engine, characterized in that, The mold is used for diffusion bonding forming of the first preform (4) and the second preform (5), and includes a lower mold (2) for assembling the second preform (5), a core mold (3) for placing between the first preform (4) and the second preform (5), and an upper mold (1) for pressing on the first preform (4), wherein, The first preform (4), the second preform (5) and the core mold (3) are all provided with ear pieces (7) at their ends. The ear pieces (7) extend out of the mold when the upper mold (1) and the lower mold (2) are closed. The ear pieces (7) of the first preform (4), the second preform (5) and the core mold (3) are fixed by pins (6). The upper mold (1) has a stepped through hole at the top corner, and the lower mold (2) has a corresponding positioning through hole. The stepped through hole and the positioning through hole are connected by a pin (6), and the pin (6) is a stepped pin. When the upper mold (1) and the lower mold (2) are closed, a gap is left between the parting surfaces. The mold also includes a gasket (9) for filling the gap. There are multiple gaskets (9), and the multiple gaskets (9) have different thicknesses.

2. The titanium alloy leading edge forming mold for aero-engine composite fan blades according to claim 1, characterized in that, The core mold (3) has a step, and the lower mold (2) has a groove that matches the step.

3. The titanium alloy leading edge forming mold for aero-engine composite fan blades according to claim 1, characterized in that, When the upper mold (1) and the lower mold (2) are closed, a prying opening structure is provided between the parting surfaces.

4. The titanium alloy leading edge forming mold for aero-engine composite fan blades according to claim 3, characterized in that, A notch is provided at at least one apex corner of the parting surface of the upper mold (1) or the lower mold (2) to form the pry hole structure.

5. The titanium alloy leading edge forming mold for aero-engine composite fan blades according to claim 1, characterized in that, The core mold (3) is provided with a threaded hole (10) that can be screwed out of the core mold (3) by thread.

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