A method for liquid expansion forming of an air engine nozzle

Abstract

The present application relates to the technical field of aircraft engine accessory machining equipment, and particularly relates to a liquid expansion forming method of an aircraft engine flow guide pipe. The present application provides a liquid expansion forming method of an aircraft engine flow guide pipe, which solves the technical problem of high processing cost of the flow guide pipe processing method in the prior art. The liquid expansion forming method of the aircraft engine flow guide pipe comprises the following steps: manufacturing a blank, and the present application adopts liquid to replace the existing technology of filling tin, lead and other methods for forming, which reduces the number of steps and greatly improves the efficiency. Compared with the filling method of tin, lead and other methods, since the materials of tin, lead and other metals are not the same as those of the blank, even if tin, lead is filled, the forming precision of the flow guide pipe cannot be effectively guaranteed. However, since the compression ratio of the liquid is small, especially the compression ratio of hydraulic oil and cutting fluid can be ignored, the pressure of the liquid in the blank can be effectively maintained, and the forming precision of the flow guide pipe is improved.

Description

Technical Field

[0001] This invention relates to the field of aero-engine component processing equipment technology, and in particular to a method for hydraulic expansion forming of aero-engine guide tubes. Background Technology

[0002] The engine air intake is a thin-walled cylindrical component with an elliptical cross-section and an appearance like... Figure 1 As shown, based on its structural characteristics, it is divided into the following parts: large end, small end, blade basin, blade back, and raised rib structure. The guide tube is installed inside the cavity of the low-pressure first-stage guide vane of the engine, with its upper and lower end faces tightly fitting the flanges of the blade end faces. Its shape is an arc-shaped, bent, and flat tube structure. The guide tube is a key component of third- and fourth-generation aero-engines, operating in a high-temperature, high-pressure, and high-oxygen environment for extended periods. Therefore, it places extremely high demands on the high-temperature resistance, oxidation resistance, and fatigue resistance of the materials used.

[0003] The guide tube is usually made by the traditional method of ordinary thermoforming and welding. This method has the following disadvantages: (1) The scrap rate of ordinary thermoforming is high and the quality is unstable. (2) Due to the presence of welds, the fatigue limit of the guide tube is low in high temperature environment, resulting in a short service life of the aero engine and the need for frequent overhaul, which seriously affects the sortie rate of the fighter jet.

[0004] To improve the yield of guide tubes, existing technologies employ a metal-filling method. This involves adding molten metal to the guide tube blank, allowing the metal to cool and solidify, then pressure-forming the blank. After forming, the solidified metal is melted down to obtain the finished product. While this method effectively increases the yield, it is cumbersome and produces low-yield products. It requires multiple fillings of the blank with metals of different melting points; at least two types of metals are needed to produce a single guide tube. The first metal is used for initial forming, followed by a second metal for a second forming process. Furthermore, the melting process may generate harmful gases, further increasing the manufacturing cost of the guide tubes.

[0005] Therefore, the existing methods for processing guide tubes have the technical problem of high processing costs. Summary of the Invention

[0006] The present invention provides a method for hydraulic expansion forming of an aero-engine guide tube, which solves the technical problem of high processing cost in the existing guide tube processing methods.

[0007] Some implementation schemes for solving the above-mentioned technical problems include:

[0008] A method for hydraulic expansion forming of an aero-engine guide tube includes the following steps:

[0009] Manufacture the blank according to the shape of the guide tube before bending, and leave cutting allowance at both ends of the blank.

[0010] The blank is machined by machining mating parts that mate with the sealer at both ends of the finished blank to obtain the finished blank.

[0011] Install sealers at both ends of the finished blank, the sealers being provided with injection nozzles for injecting liquid into the finished blank;

[0012] The process blank is obtained by adding liquid to the finished blank after the sealer is installed through the injection nozzle, and the pressure of the liquid in the finished blank is equal to the compressive strength of the blank.

[0013] Preliminary forming: The preliminary forming mold is used to preliminarily form the process blank to obtain a rough finished product, wherein the liquid pressure in the process blank during the preliminary forming process is equal to the compressive strength of the blank.

[0014] Shaping involves using a shaping mold to shape the rough product into a finished product, wherein the liquid pressure in the rough product during the shaping process is equal to the compressive strength of the blank.

[0015] Remove the excess, remove the seals at both ends of the finished product, drain the liquid from the finished product, and then remove the excess from the finished product to obtain the guide tube.

[0016] Preferably, the initial forming mold includes a roller and an elastic layer disposed outside the roller. The roller contacts the process blank through the elastic layer, and the elastic layer makes surface contact with the process blank after elastic deformation.

[0017] Preferably, the initial forming includes the following steps:

[0018] The process blank is fixed by using a fixing clamp to fix both ends of the process blank, wherein the fixing clamp and the two ends of the process blank are in surface contact.

[0019] Roll forming involves rolling the process blank from one end to the other along the bending direction of the guide tube using rollers. The distance the rollers move along the bending direction of the guide tube in a single operation is no more than 5 millimeters. Furthermore, the pressure of the liquid in the process blank is monitored in real time during the initial forming process, and the pressure of the liquid in the process blank is kept constant.

[0020] Preferably, during the roll forming process, the distance that the roller moves along the bending direction of the guide tube in a single step gradually decreases.

[0021] Preferably, the thickness of the elastic layer is no more than 5 mm.

[0022] Preferably, the shaping mold includes a first half and a second half, the first half being provided with a protrusion arranged along the bending direction of the guide tube, and the second half being provided with a shaping cavity that cooperates with the protrusion to shape the rough finished product.

[0023] Preferably, in the shaping process, the rough finished product is first placed in the shaping cavity of the second half, and then the first half is moved to fit with the second half, and the position of the first half is maintained for at least 120 seconds.

[0024] Preferably, the length of the mating portion is not less than the length of the seal extending into the mating portion.

[0025] Preferably, the mating part is truncated cone in shape, and the taper of the mating part is a Morse taper.

[0026] Preferably, the sealer includes an extension extending into the mating portion, and a sealing gasket is provided between the extension and the mating portion. The sealing gasket extends toward the middle of the finished blank in the length direction, and the sealing gasket is pressed against the side wall of the mating portion by the pressure of the liquid filled in the finished blank. The liquid filled in the finished blank is hydraulic oil, or the liquid filled in the finished blank is cutting fluid.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] This solution uses liquid instead of tin or lead as fillers in existing technologies for molding, reducing multiple process steps and significantly improving efficiency. Furthermore, because the pressure of the liquid in the blank can be easily controlled, it maintains a reasonable pressure value at all times. In contrast, using tin or lead, where the metals are different from the blank material, cannot effectively guarantee the molding accuracy of the guide tube. With liquid filling, the low compressibility of liquids, especially hydraulic oil and cutting fluids (whose compressibility is negligible), effectively maintains the liquid pressure in the blank, improving the molding accuracy of the guide tube and reducing its manufacturing cost.

[0029] By using liquid instead of metals such as tin and lead, the pollution and health hazards to workers caused by the repeated heating and liquefaction of heavy metals such as tin and lead are reduced. Furthermore, the liquid in the guide tube forming process effectively ensures uniform wall thickness across the curved surfaces of the parts, avoiding risks such as cracking and inconsistent wall thickness, thus maximizing the optimization of part machining accuracy.

[0030] The guide tube is processed in two steps: initial forming and final forming. This results in higher forming accuracy and improved product yield. Attached Figure Description

[0031] For illustrative purposes, several embodiments of the invention are illustrated in the following figures. These figures are incorporated herein by reference and form part of the detailed description. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring the concept of the subject matter of the invention.

[0032] Figure 1 This is a cross-sectional view of the sealer after it has been installed on the blank, i.e., the shape of the process blank before the liquid has been added.

[0033] Figure 2 for Figure 1 A schematic diagram.

[0034] Figure 3 This is a schematic diagram of the seal at the first angle.

[0035] Figure 4 This is a schematic diagram of the second angle of the seal.

[0036] Figure 5 This is a schematic diagram of the roller.

[0037] Figure 6 This is a process flow diagram of the present invention.

[0038] As shown in the figure:

[0039] 1. Drainage tube.

[0040] 2. Sealer, 21. Sealing gasket, 22. Injection nozzle.

[0041] 3. Rollers. Detailed Implementation

[0042] The specific embodiments shown below are intended to describe various configurations of the subject matter of the invention and are not intended to represent the only configuration in which the subject matter of the invention can be practiced. The specific embodiments include particular details intended to provide a thorough understanding of the subject matter of the invention. However, it will be clear and apparent to those skilled in the art that the subject matter of the invention is not limited to the specific details shown herein and can be practiced without these specific details.

[0043] Understandably, in this document, relational terms such as “first” and “second” are intended to distinguish one entity or operation from another, and are not intended to expressly or imply any actual relationship or order between these entities or operations.

[0044] The terms “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0045] Reference Figures 1 to 6 As shown, a method for hydraulic expansion forming of an aero-engine guide tube includes the following steps:

[0046] Manufacture the blank according to the shape of the guide tube 1 before bending, and leave cutting allowance at both ends of the blank.

[0047] The blank is processed by machining mating parts that mate with the sealer 2 at both ends of the finished blank to obtain the finished blank.

[0048] Install sealer 2 at both ends of finished blank, the sealer 2 being provided with injection nozzle 22 for injecting liquid into finished blank;

[0049] Liquid is added to the finished blank after the sealer 2 is installed through the injection nozzle 22 to obtain a process blank, and the pressure of the liquid in the finished blank is equal to the compressive strength of the blank.

[0050] Preliminary forming: The preliminary forming mold is used to preliminarily form the process blank to obtain a rough finished product, wherein the liquid pressure in the process blank during the preliminary forming process is equal to the compressive strength of the blank.

[0051] Shaping involves using a shaping mold to shape the rough product into a finished product, wherein the liquid pressure in the rough product during the shaping process is equal to the compressive strength of the blank.

[0052] Remove the excess, remove the seals 2 at both ends of the finished product, drain the liquid from the finished product, and then remove the excess from the finished product to obtain the guide tube 1.

[0053] In some embodiments, excess material can be removed by wire cutting or electrical discharge machining. That is, during the process of removing excess material, the finished product should be subjected to the smallest possible force to prevent deformation of the finished product and thus scrapping it.

[0054] In some initial draft examples, the initial forming mold includes a roller 3 and an elastic layer disposed outside the roller 3. The roller 3 contacts the process blank through the elastic layer, and the elastic layer makes surface contact with the process blank after elastic deformation.

[0055] In some embodiments, the initial molding includes the following steps:

[0056] The process blank is fixed by using a fixing clamp to fix both ends of the process blank, wherein the fixing clamp and the two ends of the process blank are in surface contact.

[0057] Roll forming involves rolling the process blank from one end to the other along the bending direction of the guide tube 1 using rollers 3. The distance that the rollers 3 move in a single step along the bending direction of the guide tube 1 is no more than 5 mm. Furthermore, during the initial forming process, the pressure of the liquid in the process blank is monitored in real time and kept constant.

[0058] In some embodiments, the fixing fixture may adopt a split structure, that is, the fixing fixture includes at least two clamping arms, both of which are in surface contact with the process blank to ensure uniform force on the process blank. The process blank is fixed when at least two clamping arms are in contact with the process blank, and the process blank is released when at least two clamping arms are out of contact with the process blank.

[0059] In some embodiments, during the roll forming process, the distance that the roller 3 moves in a single step along the bending direction of the guide tube 1 gradually decreases. Since the shape of the process blank is closer to the end of the roll forming process than the guide tube 1, using a smaller moving distance for the roller 3 can prevent damage to the process blank or other forms of failure.

[0060] In some embodiments, the thickness of the elastic layer is no greater than 5 mm. The thickness of the elastic layer can be determined based on the distance the roller 3 moves in a single movement; that is, the greater the distance the roller 3 moves in a single movement, the thicker the elastic layer can be.

[0061] Understandably, the elastic layer is mainly used to increase the contact area between the roller 3 and the process blank, preventing defects from occurring on the process blank due to a small contact area. Therefore, the thickness of the elastic layer is not limited. When the material of the guide tube 1 does not require the use of a process blank, or when the roller 3 can maintain a reasonable contact area with the process blank, the elastic layer may not be required.

[0062] In some embodiments, roll forming refers to using rollers 3 to contact the process blank, causing the process blank to bend and deform. Specifically, taking the bending of the process blank in the negative Y-axis direction as an example, rollers 3 reciprocate along the X-axis, where the X-axis and Y-axis are perpendicular to each other. When rollers 3 move along the X-axis, they advance a certain distance in the negative Y-axis direction each time, which is the distance that rollers 3 move in a single bending direction along the guide tube 1. Using this method for initial forming results in a smaller deformation of the process blank per cycle, making it less prone to defects.

[0063] In some embodiments, the shaping mold includes a first half and a second half, the first half being provided with a protrusion disposed along the bending direction of the guide tube 1, and the second half being provided with a shaping cavity that cooperates with the protrusion to shape the rough finished product.

[0064] In some embodiments, during the shaping process, the rough finished product is first placed in the shaping cavity of the second half, and then the first half is moved to mate with the second half, and the position of the first half is maintained for at least 120 seconds.

[0065] Understandably, the longer the first half is held, the higher the precision of the finished product.

[0066] In some embodiments, the length of the mating portion is not less than the length of the seal 2 extending into the mating portion. The mating portion is completely removed during subsequent processing, which can effectively ensure the overall accuracy of the guide tube 1.

[0067] In some embodiments, the mating part is truncated cone-shaped, and the taper of the mating part is a Morse taper. The Morse taper has a certain sealing performance, which makes the sealer 2 have better sealing characteristics and the liquid pressure in the blank more stable.

[0068] In some embodiments, the sealer 2 includes an extension extending into the mating portion, and a sealing gasket 21 is disposed between the extension and the mating portion. The sealing gasket 21 extends toward the middle of the finished blank in the length direction, and the sealing gasket 21 is pressed against the side wall of the mating portion by the pressure of the liquid filled into the finished blank.

[0069] In some embodiments, the liquid filling the finished blank is hydraulic oil, or the liquid filling the finished blank is cutting fluid.

[0070] The technical solution of the present invention will be further described below with reference to a specific application example:

[0071] Reference Figures 1 to 6 As shown, in step 1, a blank is manufactured using the material of the guide tube 1. The blank is manufactured according to the shape of the guide tube 1 before bending, and a cutting allowance is reserved at both ends of the blank. The cutting allowance can be determined according to the length of the sealer 2 extending into the blank.

[0072] Step 5: Machining the blank. After the blank is manufactured, machining mating parts that mate with the sealer 2 at both ends to obtain the finished blank. At this time, the blank is in the shape of a straight rod, and the mating parts can be machined using a lathe or other machining equipment. The mating parts are located on the relatively smooth inner walls at both ends of the blank, so that the mating parts can mate with the sealer 2 to effectively seal the blank and prevent liquid leakage inside the blank.

[0073] Step 10: Install the sealer 2. Install the sealer 2 at both ends of the finished blank. The sealer 2 is equipped with an injection nozzle 22 for injecting liquid into the finished blank. The sealer 2 can be installed at both ends of the finished blank in any way and mate with the mating part. For example, other limiting tools can be used to limit the sealer 2 to prevent it from detaching from the finished blank. Alternatively, threaded fasteners or other fasteners can be used to fix the sealer 2 to the finished blank.

[0074] Step 15: Fill the blank with liquid through the injection nozzle 22. A one-way valve can be installed inside the injection nozzle 22 to prevent liquid leakage. The liquid can be hydraulic oil or environmentally friendly cutting fluid. The liquid is added to the finished blank after the sealer 2 is installed through the injection nozzle 22 to obtain the process blank. The pressure of the liquid in the finished blank is equal to the compressive strength of the blank. The liquid can be added to the finished blank using an injection pump. The injection pump can be equipped with a pressure sensor to detect the liquid pressure in the blank. When the liquid pressure in the blank changes, the injection pump works in time to keep the liquid pressure in the blank constant.

[0075] Step 20: Use roller 3 to complete the initial forming. Use the initial forming mold to initially form the process blank to obtain the rough finished product. In the initial forming process, the liquid pressure in the process blank is equal to the compressive strength of the blank. The forming method parameters have been introduced above and will not be repeated here.

[0076] Step 25: Final shaping. The rough product is shaped using a shaping mold to obtain the finished product. During the shaping process, the liquid pressure in the rough product is equal to the compressive strength of the blank. The shaping mold is a copying mold, that is, the shaping mold and the rough product are in surface contact.

[0077] Step 30: Remove excess material by wire cutting or EDM, remove the seals 2 at both ends of the finished product, drain the liquid from the finished product, and then remove the excess material from the finished product to obtain the guide tube 1.

[0078] In this specification, "blank," "finished blank," "rough finished product," and "finished product" all refer to different states of the blank and are used only to clearly describe the different names used for blanks in different states. However, in the accompanying drawings, for clarity, the uniform reference 'guide tube 1' is used to represent blanks in different states and the guide tube 1.

[0079] The technical solution of the present invention and its corresponding details have been described above. It is understood that the above description is only some implementation schemes of the technical solution of the present invention, and some details may be omitted in the specific implementation.

[0080] Furthermore, in some embodiments of the above invention, multiple embodiments may be combined; however, due to space limitations, all such combinations will not be listed here. Those skilled in the art can freely combine and implement the above embodiments according to their needs to obtain a better application experience.

[0081] When implementing the subject matter of this invention, those skilled in the art can obtain other detailed configurations or drawings based on the subject matter and drawings. Obviously, these details are still within the scope of the subject matter of this invention without departing from it.

Claims

1. A method for hydraulic expansion forming of an aero-engine guide tube, characterized in that, Includes the following steps: To manufacture a blank, the blank is manufactured according to the shape of the guide tube (1) before bending, and a cutting allowance is reserved at both ends of the blank. Process the blank, and process the mating parts that mate with the sealer (2) at both ends of the blank after the manufacturing is completed to obtain the finished blank; Install seals (2) at both ends of the finished blank, the seals (2) being provided with injection nozzles (22) for injecting liquid into the finished blank; Filling liquid: Liquid is added to the finished blank after the sealer (2) is installed through the injection nozzle (22) to obtain a process blank, and the pressure of the liquid in the finished blank is equal to the compressive strength of the blank. Preliminary forming: The preliminary forming mold is used to preliminarily form the process blank to obtain a rough finished product, wherein the liquid pressure in the process blank during the preliminary forming process is equal to the compressive strength of the blank. Shaping involves using a shaping mold to shape the rough product into a finished product, wherein the liquid pressure in the rough product during the shaping process is equal to the compressive strength of the blank. Remove the excess, remove the seals (2) at both ends of the finished product, drain the liquid from the finished product, and then remove the excess from the finished product to obtain the guide tube (1); The initial forming mold includes a roller (3) and an elastic layer disposed outside the roller (3). The roller (3) contacts the process blank through the elastic layer, and the elastic layer makes surface contact with the process blank after elastic deformation. The initial molding process includes the following steps: The process blank is fixed by using a fixing clamp to fix both ends of the process blank, wherein the fixing clamp and the two ends of the process blank are in surface contact. Roll forming: along the bending direction of the guide tube (1), the process blank is rolled from one end to the other end by rollers (3). The distance that the rollers (3) move along the bending direction of the guide tube (1) in a single operation is no more than 5 mm. In addition, during the initial forming process, the pressure of the liquid in the process blank is monitored in real time and the pressure of the liquid in the process blank is kept constant. During the roll forming process, the distance that the roller (3) moves along the bending direction of the guide tube (1) in a single step gradually decreases.

2. The method for forming aero-engine guide tube by hydraulic expansion according to claim 1, characterized in that: The thickness of the elastic layer is no more than 5 mm.

3. The method for forming aero-engine guide tube by hydraulic expansion according to claim 1, characterized in that: The shaping mold includes a first half and a second half. The first half is provided with a protrusion arranged along the bending direction of the guide tube (1), and the second half is provided with a shaping cavity that cooperates with the protrusion to shape the rough finished product.

4. The method for hydraulic expansion forming of an aero-engine guide tube according to claim 3, characterized in that: In the shaping process, the rough finished product is first placed in the shaping cavity of the second half, and then the first half is moved to fit with the second half, and the position of the first half is maintained for at least 120 seconds.

5. The method for hydraulic expansion forming of an aero-engine guide tube according to claim 1, characterized in that: The length of the mating part is not less than the length of the seal (2) extending into the mating part.

6. The method for forming aero-engine guide tube by hydraulic expansion according to claim 5, characterized in that: The mating part is shaped like a frustum, and the taper of the mating part is a Morse taper.

7. The method for hydraulic expansion forming of an aero-engine guide tube according to claim 6, characterized in that: The seal (2) includes an extension extending into the mating part, and a sealing gasket (21) is provided between the extension and the mating part. The sealing gasket (21) extends toward the middle of the finished blank in the length direction, and the sealing gasket (21) is pressed against the side wall of the mating part by the pressure of the liquid filled into the finished blank. The liquid filled into the finished blank is hydraulic oil, or the liquid filled into the finished blank is cutting fluid.

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