A method for preparing a hollow blade

Abstract

A method for manufacturing a hollow blade, using a hot isostatic pressing (HIP) process, includes the following steps: dividing the blade into upper and lower parts, providing a jacket and a core, respectively; filling the upper and lower jackets with powder, respectively, and performing warm isostatic pressing to obtain upper and lower powder blanks; cutting the jacket at the connecting portion, removing the core, and welding the upper and lower jackets together to form a single jacket, thereby connecting the upper and lower powder blanks; installing a pressurizing fixture on the single jacket and performing HIP to obtain a single hollow blade. This method can simplify the hollow blade manufacturing process and improve the quality of the finished product.

Description

Technical Field

[0001] The invention belongs to the field of aviation engines, and particularly relates to a method for preparing a hollow blade. Background Art

[0002] As load-bearing components of the intermediate casing, aircraft engine fan outlet guide vanes (FGVs) must resist vibration, impact damage, and withstand high loads. They are crucial components of modern high-bypass-ratio turbofan engines. With the development of the aviation industry, the demand for engine weight reduction is increasing. Currently, hollow FGVs are a trend in engine design and manufacturing. For example, the FGVs in the RB211-535E4 engine from British RR utilize hollow titanium alloy structures filled with vibration-damping materials. The aluminum alloy FGVs in the Leap X engine are manufactured using bonding or welding processes, significantly reducing blade weight. Currently, hollow blades are typically manufactured by milling the hollow structure onto a baseplate. The cover and baseplate are then joined using bonding, diffusion welding, friction stir welding, or electron beam welding. These processes suffer from low bonding strength, which can lead to debonding during service. Welding can result in significant part deformation and an inability to control the dimensions of the internal cavity. Furthermore, the processing steps are complex, resulting in low material utilization and a long manufacturing cycle.

[0003] Hot isostatic pressing (HIP) technology has developed rapidly in recent years, finding widespread application in applications such as engine rotor blade manufacturing. Parts manufactured using HIP exhibit uniform microstructure, excellent mechanical properties, and near-net-shape properties. The process is simple and suitable for the manufacture of complex structures. However, due to the unique structural characteristics of hollow blades, a direct HIP solution for their production is currently lacking. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a hollow blade, wherein the hollow blade is prepared in a near-net-shape manner by a hot isostatic pressing process, so as to improve the quality of the finished blade and simplify the manufacturing process.

[0005] According to one aspect of an embodiment of the present invention, a method for preparing a hollow blade is provided, the method comprising the following steps:

[0006] a) dividing the hollow blade into two parts, an upper part and a lower part, and providing a cover and a core for the hollow blade, wherein the cover includes an upper cover and a lower cover;

[0007] b) filling the upper and lower jackets with powdered raw materials and inserting cores, respectively, and welding the jackets to seal them;

[0008] c) performing warm isostatic pressing on the upper and lower packages respectively, so that the powder raw materials are combined into upper and lower powder blanks with fixed shapes;

[0009] d) cutting off the sheath on the connection surface between the upper and lower parts and removing the core, splicing and welding the upper and lower sheaths along the cut surface to form a blade sheath, so that the upper powder blank and the lower powder blank are connected as a whole within the blade sheath;

[0010] e) drilling a hole at one end of the blade cover to connect the cavity left after the core is removed to the outside;

[0011] f) installing a pressure fixture on the blade cover to apply additional pressure to the blade cover from both ends along the height direction;

[0012] g) placing the blade cover and the pressurizing fixture together into a hot isostatic pressing furnace for hot isostatic pressing, so that the metal powders in the upper powder blank and the lower powder blank are connected to form an integral hollow blade.

[0013] This method can be used to produce near-net-shape hollow blades using a hot isostatic pressing process. The finished blades have uniform structure, good strength, and low deformation and internal stress. The equipment required for the processing is simple, and there is no need for complex processes such as milling, resulting in a high material utilization rate.

[0014] Furthermore, there are two cores respectively installed in the upper and lower covers. The two cores can form two independent cavities in the blade, thereby improving the strength of the blade while reducing its weight.

[0015] Furthermore, the core is made of steel or ceramic, which is easy to manufacture and demould.

[0016] Furthermore, the dividing position between the upper and lower parts of the hollow blade is the position where the stress along the height direction is the lowest when the blade is in service. Setting the dividing position at the position where the stress is the lowest can improve the reliability of the component in long-term service.

[0017] Furthermore, the surface of the blade cover is provided with a reinforcement structure along the blade height direction to increase the rigidity of the blade cover along the blade height direction. The reinforcement structure can prevent the blade cover from being easily bent or damaged when subjected to additional pressure.

[0018] Furthermore, the additional pressure in step f) is ≥30 MPa at the interface between the upper and lower powder blanks. Since the pressure inside and outside the casing is the same after drilling, the additional pressure is required to provide the pressure necessary for the powders on the interface to recrystallize and fuse. Sufficient pressure is required to ensure sufficient recrystallization.

[0019] Furthermore, the powder raw material is composed of aluminum alloy or titanium alloy powder. Aluminum alloy or titanium alloy has the advantages of being light and high-strength, and is suitable for manufacturing blades.

[0020] Furthermore, the powder raw material also includes reinforcing particles, which can further improve the mechanical properties of the blade.

[0021] Furthermore, step d) further includes step d-2) prior to welding: heating the surfaces of the upper and lower powder blanks to combine the surface powder raw materials into a dense layer. Since the internal and external pressures of the can are the same after drilling, the external pressure required for recrystallization of the powder blank depends on the airtightness of the blank's surface. Preheating the surface to sinter the surface powder can improve the airtightness of the powder blank.

[0022] Furthermore, the welding method in step d) is argon arc welding. Considering the structural characteristics of the sheath, argon arc welding has good welding accessibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of an upper sheath and a lower sheath in one embodiment;

[0024] Figure 2 A schematic cross-sectional view of a casing after being filled with powder and a core in one embodiment;

[0025] Figure 3 This is a schematic diagram of the blade cover structure in one embodiment;

[0026] Figure 4 This is a schematic cross-sectional view of the casing after being filled with powder and core in another embodiment.

[0027] Figure 5 Schematic diagram of the blade cover structure in another embodiment.

[0028] The purpose of the above-mentioned drawings is to illustrate the technical solutions of the present invention in detail so that those skilled in the art can understand the technical concepts of the present invention, and is not intended to limit the present invention. It should be understood that for the sake of clarity and simplicity, the above-mentioned drawings only schematically depict certain technical features related to the technical solutions of the present invention and do not depict all detailed features and complete devices strictly to scale. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below through embodiments with reference to the accompanying drawings.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art; the terms used herein are only for describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" and their synonyms in the specification and claims and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0031] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present invention. The appearance of the term "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. Those skilled in the art will appreciate that the embodiments described herein may be combined with other embodiments.

[0032] In the description of the embodiments herein, directions or positional relationships indicated by “horizontal,” “vertical,” “length,” “height,” “radial,” “circumferential,” “upper,” and “lower” are only for the purpose of facilitating the description of the embodiments and simplifying the description, and are not intended to indicate or limit that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction, and are therefore not intended to limit the embodiments of the invention.

[0033] In the description of the embodiments herein, unless otherwise specified or indicated, the terms "mounted," "connected," and "connected" should be understood broadly, such as referring to fixed, detachable, or integrated connections; mechanical or electrical connections; and direct or through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments herein based on the specific circumstances.

[0034] According to one embodiment of the present invention, a method for preparing a hollow blade is provided for preparing a fan outlet guide vane for a turbofan engine. The method comprises the following steps:

[0035] a) Divide the hollow blade into two parts, upper and lower, along the height direction, and provide a cover and a core for them, such as Figure 1 As shown. Preferably, the upper and lower decomposition positions are set at the position where the stress along the height direction is minimized when the blade is in service. The sheath includes an upper sheath 1 and a lower sheath 2. The sheath opening is set at the docking position of the upper and lower parts of the blade. The sheath structure is made of carbon steel according to the external structure design of the blade to be manufactured. The cavity within the sheath is used to form the outer contour of the blade. The reserve required for subsequent processing is taken into account during the design.

[0036] b) Fill 2009 aluminum alloy powder and SiC reinforced particle powder in the upper and lower packages 1 and 2 respectively by vibration, and combine Figure 2, two steel cores 5 are respectively placed in the upper and lower sleeves 1 and 2. After filling, the upper and lower sleeves 1 and 2 are vacuumed and welded closed.

[0037] c) The upper and lower packages 1 and 2 are subjected to warm isostatic pressing at a pressure of 80 MPa-200 MPa for ≥5 min, so that the raw powder in the packages is combined into an upper powder blank 3 and a lower powder blank 4 of fixed shape.

[0038] d-1) The sheath at the connection surface 6 of the upper powder blank 3 and the lower powder blank 4 is removed to expose the connection surface 6 of the powder blank and the core 5, and the core 5 is pulled out.

[0039] d-2) Optionally, the upper powder blank 3 and the lower powder blank 4 are surface heated using an acetylene torch or an induction furnace to combine the powder raw materials on the surface into a dense layer to avoid insufficient airtightness of the powder blank during the subsequent hot isostatic pressing process.

[0040] d-3) If Figure 3 As shown, the upper sheath 1 and the lower sheath 2 are spliced along the cut surface and welded together along the splicing interface 8 by argon arc welding to form a blade sheath 10, so that the upper powder blank 3 and the lower powder blank 4 are connected as a whole in the blade sheath 10.

[0041] e) A through hole 7 is drilled at one end of the blade cover 10, such as the outer edge plate, so that each cavity left after the core 5 is removed is connected to the outside, so as to balance the air pressure inside and outside the blade during hot isostatic pressing.

[0042] f) Install a pressure fixture, such as a vise-like fixture with adjustable chuck spacing via a screw mechanism, on the blade wrap 10. Apply inward pressure to the blade wrap 10 from both ends of the inner and outer edge plates. Preferably, the pressure at the interface between the upper and lower powder blanks 3 and 4 is ≥ 30 MPa.

[0043] g) Place the blade cover 10 and the press fixture together in a hot isostatic pressing furnace for hot isostatic pressing at a heating temperature of 550°C-600°C, a pressure ≥80 MPa, and a holding time ≥2 hours, so that the powder inside the upper powder blank 3 and the lower powder blank 4 and on the connecting surface 6 undergo plastic deformation and diffusion creep, and are finally connected to form an integral hollow blade.

[0044] h) Remove the blisk cover 10 by mechanical treatment, and heat treat the entire hollow blade according to the heat treatment system for SiC-reinforced 2009 aluminum alloy composite materials. Specific parameters include: solution treatment at 510°C ± 5°C for 5 h ± 0.5 h, followed by water quenching for no more than 15 seconds, and natural aging at room temperature for no less than 96 h. The entire hollow blade is then subjected to water immersion testing, dimensional modification, and stress relief, completing the finished hollow blade.

[0045] Optionally, the surface of the blade cover 10 can be provided with a reinforcement structure along the height direction of the blade, such as a reinforcement plate integrally formed with the cover or welded reinforcement ribs, so as to enhance the stiffness of the blade disc cover in the height direction when the pressurizing clamp applies additional pressure to the blade cover to avoid bending and deformation.

[0046] Optionally, according to design requirements, the reinforcing particles in the raw material powder may also be TiB2, Al2O3, etc.

[0047] According to another embodiment of the present invention, a method for preparing a hollow blade is provided, comprising the following steps:

[0048] a) Divide the hollow blade into two parts, upper and lower, along the height direction, and provide a cover and a core for them, such as Figure 1 As shown. Preferably, the upper and lower decomposition positions are set at the locations where the blade has the lowest stress along the height direction when in service. The sheath comprises an upper sheath 1 and a lower sheath 2. The sheath structure is made of carbon steel according to the external structure design of the blade to be manufactured. The cavity within the sheath forms the outer contour of the blade, and the design takes into account the reserve required for subsequent processing.

[0049] b) Fill the upper and lower jackets 1 and 2 with TC4 titanium alloy powder by vibration, and combine Figure 4 , a ceramic core 5 is respectively placed in the upper cover 1 and the lower cover 2. After the filling is completed, the upper cover 1 and the lower cover 2 are vacuumed and welded closed.

[0050] c) The upper and lower packages 1 and 2 are subjected to warm isostatic pressing to combine the powder in the packages into an upper powder blank 3 and a lower powder blank 4 with fixed shapes.

[0051] d) Remove the sheath at the connection surface 6 of the upper powder blank 3 and the lower powder blank 4 to expose the connection surface 6 of the powder blank and the core 5, and then pull out the core 5. Figure 5 As shown, the upper cover 1 and the lower cover 2 are spliced along the cut surface and laser welded together along the splicing interface 8 to form a blade cover 10, so that the upper powder blank 3 and the lower powder blank 4 are connected as a whole in the blade cover 10.

[0052] e) A through hole 7 is drilled at one end of the blade cover 10, such as the outer edge plate side or the inner edge plate side, so that the cavity left after the core 5 is removed is connected to the outside, so as to balance the air pressure inside and outside the blade during hot isostatic pressing.

[0053] f) Install a pressure fixture, such as a vise-like fixture with adjustable chuck spacing via a screw mechanism, on the blade wrap 10. Apply inward pressure to the blade wrap 10 from both ends of the inner and outer edge plates. Preferably, the pressure at the interface between the upper and lower powder blanks 3 and 4 is ≥ 40 MPa.

[0054] g) Place the blade cover 10 and the pressurizing fixture together in a hot isostatic pressing furnace for hot isostatic pressing at a heating temperature of 910°C-930°C, a pressure of 120MPa-200MPa, and a holding time of 2.5h-3.5h, so that the powder inside the upper powder blank 3 and the lower powder blank 4 and on the connecting surface 6 undergo plastic deformation and diffusion creep, and are finally connected to form an integral hollow blade.

[0055] h) The blade cover 10 is removed by mechanical or acid treatment, and the entire hollow blade is heat treated according to the heat treatment system for TC4 titanium alloy composite materials, with specific parameters: homogenization at 840°C-860°C for 2 hours and furnace cooling. The entire hollow blade is then subjected to water immersion inspection, dimensional modification, and stress relief processing, finally completing the finished hollow blade.

[0056] It should be understood that the purpose of the above-described embodiments is to provide a detailed explanation of the technical solutions of the present invention in conjunction with the accompanying drawings, and is not intended to limit the present invention. Within the scope of the claims of the present invention, optimization or equivalent replacement of the parts, structures, and method steps involved in the various embodiments of the present invention, or combination of different embodiments without causing any conflict in principle or structure, all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a hollow blade, characterized in that: The following steps are involved: a) dividing the hollow blade into two parts, an upper part and a lower part, and providing a cover and a core for the hollow blade, wherein the cover includes an upper cover and a lower cover; b) filling the upper and lower jackets with powdered raw materials and inserting cores, respectively, and welding the jackets to seal them; c) performing warm isostatic pressing on the upper and lower cans respectively to combine the powder raw materials into upper and lower powder blanks with fixed shapes; d) heating the surfaces of the upper and lower powder blanks to combine the surface powder materials into a dense layer; Cutting off the sheath on the connection surface between the upper and lower parts and removing the core, splicing and welding the upper and lower sheaths along the cut surface to form a blade sheath, so that the upper powder blank and the lower powder blank are connected as a whole within the blade sheath; e) drilling a hole at one end of the blade cover to connect the cavity left after the core is removed to the outside; f) installing a pressure fixture on the blade cover to apply additional pressure to the blade cover from both ends along the height direction; g) placing the blade cover and the pressurizing fixture together into a hot isostatic pressing furnace for hot isostatic pressing, so that the metal powders in the upper powder blank and the lower powder blank are connected to form an integral hollow blade.

2. The method for preparing a hollow blade according to claim 1, characterized in that: There are two cores respectively placed in the upper and lower jackets.

3. The method for preparing a hollow blade according to claim 1 or 2, characterized in that: The material of the core is steel or ceramic.

4. The method for preparing a hollow blade according to claim 1, wherein: The dividing position of the upper and lower parts of the hollow blade is the position where the stress along the height direction is the smallest when the blade is in service.

5. The method for preparing a hollow blade according to claim 1, characterized in that: The surface of the blade cover is provided with a reinforcement structure along the blade height direction to increase the rigidity of the blade cover along the blade height direction.

6. The method for preparing a hollow blade according to claim 1 or 5, characterized in that: The additional pressure in step f) is ≥30 MPa on the bonding surface of the upper powder blank and the lower powder blank.

7. The method for preparing a hollow blade according to claim 1, characterized in that: The powder raw material is composed of aluminum alloy or titanium alloy powder.

8. The method for preparing a hollow blade according to claim 7, characterized in that: The powder raw material also includes reinforcing particles.

9. The method for preparing a hollow blade according to claim 1, characterized in that: The welding method in step d) is argon arc welding.

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