Method and apparatus for integral forming of an aeroengine lip

Abstract

The application provides a method and equipment for integrally forming an aero-engine lip, which replaces a plurality of plate blank materials used in a traditional process of first stamping and then welding with a prepared tubular blank material, and through flanging forming in a hot state, material stress of the plate material is changed from a two-way stretching state to a tensile-compressive state, so that material thinning in the forming process is reduced, compactness of internal material organization is ensured, weakening of a weld on structural strength is eliminated, and probability of micro-crack generation is greatly reduced, which is beneficial to improving comprehensive mechanical properties of the integrally formed lip. On the other hand, the application also overcomes the drawbacks of a complex process, uneven wall thickness of a finished lip product, low design margin and the like of a current inflation integrally forming mode, breaks a technical prejudice in the field that a relative depth ratio is difficult to be increased to more than 0.5, and therefore better forming effect of the lip part can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic forming technology for aero-engines, specifically relating to an integral forming method and special equipment for the lip of a large aero-engine. Background Technology

[0002] The engine lip is a crucial component of the engine's air intake. It is typically a double-flanged, deep-cavity sheet metal part. Due to its complex service conditions, requiring it to withstand high-speed airflow and resonance for extended periods, it demands extremely high standards for drawing depth, shape accuracy, and surface roughness. Driven by the urgent need for new high-performance aircraft engines, lip components are currently trending towards integration, lightweighting, precision, and low-damage designs. This is specifically manifested in the use of larger relative depth ratios (maximum drawing depth H / maximum equivalent diameter D, such as...). Figure 1 The design achieves laminar flow nacelles and reduces drag, and adopts more integral molding to enhance the structure and reduce weight. Some designs further optimize the spatial irregular curved surface structure of the lip to improve the required engine performance.

[0003] The aforementioned development trends undoubtedly place higher demands on the performance indicators of lip products and significantly increase the difficulty of manufacturing, making the shortcomings of traditional processing and forming methods increasingly prominent. For example, to manufacture engine lip parts with a large relative depth ratio, the industry currently mostly adopts a method of first forming by segmented stamping and then welding. That is, the lip-type parts are divided into two or more fan-shaped components, formed separately, and then assembled by welding. The resulting finished products generally have many problems such as poor surface quality, low post-weld precision, and insufficient mechanical properties at the weld. To prevent weld breakage, circumferential reinforcing structural components are also required, which leads to increased engine weight, safety hazards, and reduced efficiency. The integral forming method of high-pressure fluid expansion forming mostly uses thin plate forming. During the process, multiple expansion and deep drawing can be used for shaping. Although this method can improve the forming limit to a certain extent by utilizing the advantages of fluid overflow, and can also strengthen the structure and reduce weight without welds, the complicated process is prone to uneven wall thickness distribution, and the lip design margin is also limited, especially for cases where the relative depth ratio is greater than 0.5, it is still not feasible. It is evident that the existing lip forming methods for aero-engines cannot meet the requirements, hindering the full realization of the performance of engine components and the achievement of comprehensive design goals. There is an urgent need in this field for a new method for integral forming of lip parts. Summary of the Invention

[0004] In view of the above, and to address the technical problems existing in this field, the present invention provides a method for integral forming of an aero-engine lip, specifically including the following steps:

[0005] Step 1, tube blank preparation: Select a plate with a wall thickness greater than 1*t, and perform rolling and welding in sequence to prepare an initial tube blank with an initial diameter of d; where t represents the target wall thickness of the lip and d represents the target inner diameter of the lip.

[0006] Step 2, Stepped tube blank preparation: The initial tube blank is placed in a mold, and the two ends of the initial tube blank are sealed by the sealing end; the initial tube blank is heated, and when the first specified temperature is reached, the upper and lower molds of the mold are closed and a closing force is applied; during the mold closing, a high-pressure expansion medium is injected into the initial tube blank from at least one end, and the sealing end is supplied from at least one end along the axis of the initial tube blank towards the middle, thus preparing a stepped tube blank with at least one thinner tube end;

[0007] Step 3, Preparation of inner flange tube blank: The stepped tube blank is installed on the flange mold; the flange mold and the stepped tube blank are heated, and the flange mold is closed when the second specified temperature is reached to complete the inner flange under hot condition and obtain the inner flange tube blank.

[0008] Step 4: Cutting and shaping the inner-flanged tube blank: After cutting the inner-flanged tube blank to obtain the specified shape, it is then shaped.

[0009] Step 5: Adjust wall thickness: Perform milling or other processes as needed to adjust the wall thickness or remove excess parts to better meet the lip design requirements; at this point, the overall forming of the aero-engine lip is completed.

[0010] Furthermore, in step two, during mold closing, the sealing end is supplied from both ends of the initial tube blank to its middle, and the stepped tube blank with thinner ends and thicker middle is prepared.

[0011] Furthermore, in step three, for the stepped tube blank that is thinner at both ends and thicker in the middle, a cutting step is also included before it is installed on the flanging mold. Specifically, the thicker middle part of the stepped tube blank is cut along a plane perpendicular to its axis.

[0012] Furthermore, the flanging die used in step three is provided with a lower flanging die that abuts against the inner wall of the thicker end of the stepped tube blank, and a plurality of upper flanging dies corresponding to each lobe contained in the target lip shape; each upper flanging die includes a force-applying surface that abuts against the thinner end face of the stepped tube blank; the upper flanging die and the lower flanging die perform a specified relative movement and close the die when the second specified temperature is reached.

[0013] Furthermore, through the flanging and molding in step three and / or the shaping in step four, different target shapes and / or target dimensions are formed in various parts of the inner and outer surfaces of the lip.

[0014] Furthermore, the plate material is specifically selected from metal materials such as aluminum and steel, alloy materials such as aluminum alloys, or composite materials such as resin-based carbon fiber.

[0015] Furthermore, the shaping in step five is carried out using either high-pressure bulging or a rigid mold closing method.

[0016] Accordingly, the present invention also provides an integral forming apparatus for an aero-engine lip that performs the above-described method.

[0017] Accordingly, the present invention also provides an aircraft engine lip, manufactured using the above-described method.

[0018] The integral forming method for aero-engine lips provided by the present invention replaces the multi-plate blanks used in the traditional multi-lobed stamping and welding process with a tubular blank. Through a hot-state flanging forming process, the material stress on the sheet metal is transformed from a biaxial tensile state to a tensile-compressive state. This reduces material thinning during forming, ensures the density of the internal structure, and eliminates the weakening of structural strength by welds, thereby significantly reducing the probability of microcrack formation and improving the overall mechanical properties of the integral lip. Furthermore, the present invention overcomes the drawbacks of existing integral forming methods, such as complex processes, uneven wall thickness of the finished lip, and low design margin. It also breaks the technical prejudice in the field that it is difficult to increase the relative depth ratio to above 0.5, thus enabling the lip part to achieve better forming results. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the principle of the relative depth ratio of lips and mouth.

[0020] Figure 2 This is a flowchart illustrating the method provided by the present invention;

[0021] Figure 3 This is a schematic diagram illustrating the step-by-step tube blank preparation process in the method provided by the present invention.

[0022] Figure 4 This is a schematic diagram illustrating the internal flanging blank preparation steps in the method provided by the present invention.

[0023] Figure 5 This is a schematic diagram illustrating the principle of the inner flange tube blank cutting and shaping steps in the method provided by the present invention;

[0024] Figure 6 A schematic diagram of the existing traditional lip structure;

[0025] Figure 7 This is a schematic diagram of a novel lip structure. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0027] The integral forming method for the aero-engine lip provided by this invention, such as Figure 1 , 2 As shown, the specific steps include:

[0028] Step 1, tube blank preparation: Select a plate with a wall thickness greater than 1*t, and perform rolling and welding in sequence to prepare an initial tube blank with an initial diameter of d; where t represents the target wall thickness of the lip and d represents the target inner diameter of the lip.

[0029] Step 2, Stepped tube blank preparation: (e.g.) Figure 3 As shown, the initial tube blank is placed in a mold, and the openings at both ends of the initial tube blank are sealed by a sealing end; the initial tube blank is heated, and when a first specified temperature is reached, the upper and lower molds of the mold are closed and a closing force is applied; during the mold closing, a high-pressure expansion medium is injected into the initial tube blank from at least one end, and the sealing end is supplied from at least one end along the axis of the initial tube blank towards the middle, thereby preparing a stepped tube blank with at least one thinner tube end;

[0030] Step 3: Preparation of the inner-flanged tube blank: (e.g.) Figure 4 As shown, the stepped tube blank is installed on the flanging die; the flanging die and the stepped tube blank are heated, and the flanging die is closed when the second specified temperature is reached, thus completing the hot internal flanging to obtain the internally flanged tube blank.

[0031] Step 4: Cutting and Shaping the Inwardly Flanged Tube Blank: After cutting the inwardly flanged tube blank to obtain the specified shape, it is then shaped. Figure 5 This illustrates an optional shaping method using a rigid mold for mold closing;

[0032] Step 5: Adjust wall thickness: Perform milling or other processes as needed to adjust the wall thickness or remove excess material to better meet the lip design requirements; if the finished product obtained from the previous steps already meets the expected specifications, this step can be omitted. At this point, the overall forming of the aero-engine lip is complete.

[0033] In a preferred embodiment of the present invention, during step two, when the mold is closed, the sealing end is supplied from both ends of the initial tube blank to the middle, and the stepped tube blank with thinner ends and thicker middle is prepared. Figure 3The image shows a stepped tube blank that is thinner at both ends and thicker in the middle. For this stepped tube blank, it can be cut from the thicker middle part of the stepped tube blank along a plane perpendicular to its axis to obtain two stepped tube blanks that are thinner at one end and thicker at the other end. These blanks can be installed on a flanging die to perform hot flanging. The specific cutting position is not limited to the midpoint of the axis and can be flexibly adjusted according to actual needs.

[0034] In a preferred embodiment of the present invention, in step four, the molding and shaping process is used to make each part of the outer surface of the lip have a different target shape or size. Figure 7 This illustrates a novel optional lip design that can be ultimately obtained, featuring a structure with a small circumferential curvature and a wide axial width in the upper half of the outer surface, and a large circumferential curvature and a narrow axial width in the lower half. This structure can be formed either solely in the inward flanging step of this invention, or solely through high-pressure inflation shaping or... Figure 5 The rigid mold shown can be used to shape the material, or it can be achieved by combining the inner flanging and shaping processes.

[0035] The flanging mold used for the inner flanging can be a large, integral mold pre-manufactured to target the lip design, or it can be the preferred multi-lobed flanging mold provided by this invention, the specific structure of which is as follows: Figure 4 As shown, it is provided with a lower flanging die that abuts against the inner wall of the thicker end of the stepped tube blank, and a plurality of upper flanging dies corresponding to the lobes included in the target lip shape; each of the upper flanging dies includes a force-applying surface that abuts against the thinner end face of the stepped tube blank; the upper flanging die and the lower flanging die perform a specified relative movement and close the mold when the second specified temperature is reached.

[0036] For certain novel lip designs, such as curved surfaces that are recessed towards their axis or protrude outwards near or in the middle of the front and rear ends of the inner flange, those skilled in the art, based on the teachings of this invention, should understand that some auxiliary means known in the art should also be adopted in specific implementations. For example, for the aforementioned curved surface structures, an additional inner flange step can be used to form a rear sealing flange to improve the degree of heat sealing during the preparation process of the target inner flanged tube blank or high-pressure bulging forming. The shape of the flanged die can also be adjusted as needed to form appropriate contact between it and the inner wall of the inner flange to ensure the forming effect. These optional auxiliary means do not constitute any limitation on the scope of protection of the claims of this application.

[0037] In comparison Figure 6 The traditional style of the lip shown, with its relatively regular spatial curved surface and low relative depth ratio, is gradually no longer in line with the current design trends and performance requirements, especially for large aero-engines.

[0038] In a preferred embodiment of the present invention, the plate material is specifically selected from metal materials such as aluminum and steel, alloy materials such as aluminum alloys, or composite materials such as resin-based carbon fiber.

[0039] It should be understood that the sequence number of each step in the embodiments of the present invention does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for integral forming of an aero-engine lip, characterized in that: Specifically, the following steps are included: Step 1, tube blank preparation: Select a plate with a wall thickness greater than 1*t, and perform rolling and welding in sequence to prepare an initial tube blank with an initial diameter of d; where t represents the target wall thickness of the lip and d represents the target inner diameter of the lip. Step 2, Stepped tube blank preparation: The initial tube blank is placed in a mold, and the two ends of the initial tube blank are sealed by the sealing end; the initial tube blank is heated, and when the first specified temperature is reached, the upper and lower molds of the mold are closed and a closing force is applied; during the mold closing, a high-pressure expansion medium is injected into the initial tube blank from at least one end, and the sealing end is supplied from at least one end along the axis of the initial tube blank towards the middle, thus preparing a stepped tube blank with at least one thinner tube end; Step 3, Preparation of inner flange tube blank: The stepped tube blank is installed on the flange mold; the flange mold and the stepped tube blank are heated, and the flange mold is closed when the second specified temperature is reached to complete the inner flange under hot condition and obtain the inner flange tube blank. Step 4: Cutting and shaping the inner-flanged tube blank: After cutting the inner-flanged tube blank to obtain the specified shape, it is then shaped. Step 5: Adjust wall thickness: Adjust the wall thickness or remove excess material as needed; The overall forming of the aircraft engine lip is now complete.

2. The method as described in claim 1, characterized in that: In step two, when the mold is closed, the sealing end is supplied from both ends of the initial tube blank to the middle, and the stepped tube blank with thinner ends and thicker middle is formed.

3. The method as described in claim 2, characterized in that: Step three includes a cutting step for the stepped tube blank, which is thinner at both ends and thicker in the middle, before it is installed on the flanging mold. Specifically, the thicker part of the stepped tube blank is cut along a plane perpendicular to its axis.

4. The method as described in claim 1, characterized in that: The flanging die used in step three is provided with a lower flanging die that abuts against the inner wall of the thicker end of the stepped tube blank, and a plurality of upper flanging dies corresponding to the lobes included in the target lip shape; each of the upper flanging dies includes a force-applying surface that abuts against the thinner end face of the stepped tube blank; the upper flanging die and the lower flanging die perform a specified relative movement and close the die when the second specified temperature is reached.

5. The method as described in claim 1, characterized in that: Through the flanging and molding in step three and / or the shaping described in step four, different target shapes and / or target dimensions are formed in various parts of the inner and outer surfaces of the lip.

6. The method as described in claim 1, characterized in that: The sheet material is specifically selected from aluminum, steel, aluminum alloy, and resin-based carbon fiber.

7. The method as described in claim 1, characterized in that: The shaping in step five is carried out using either high-pressure bulging or rigid mold closing.

8. An integral forming device for an aircraft engine lip, characterized in that: The lip and mouth are integrally shaped by performing the method as described in any one of claims 1-7.

9. An aircraft engine lip, characterized in that: Manufactured using the method described in any one of claims 1-7.

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