Reinforced open composite centrifugal impeller and manufacturing method thereof

Abstract

The application belongs to the technical field of composite material manufacturing, and particularly relates to a reinforced open-type composite centrifugal impeller and a manufacturing method thereof. The method comprises the following steps: dividing an upper structure of the impeller into a plurality of groove-shaped blade-disc modules, respectively pre-preparing the modules, arranging a pin insertion area at a splicing section of adjacent modules, laying reinforcing prepreg, and arranging a Z-PIN array intersecting with the splicing section according to the arrangement; the Z-PINs are arranged along a predetermined folding direction of the adjacent modules as a whole, part of the Z-PINs are inclined relative to the normal direction of the splicing section in a plane perpendicular to the rotating shaft of the impeller to a predetermined interface main shear load direction, and the inclination does not hinder the folding assembly of the adjacent modules; a blade-disc upper assembly with a thick bridge connection effect is formed through secondary curing, and then the assembly is integrally cured with an unsolidified hub-disc lower structure to obtain the reinforced open-type composite centrifugal impeller. The application improves the interlayer anti-peeling and shear capacity of the module splicing section, and is suitable for the open-type composite centrifugal impeller under high-speed working conditions.

Description

Technical Field

[0001] This invention belongs to the field of composite material manufacturing technology, specifically relating to a reinforced open composite material centrifugal impeller and its manufacturing method. Background Technology

[0002] As a core component of rotating machinery (such as fans, compressors, turbochargers, and centrifugal compressors), the performance of centrifugal impellers directly determines the efficiency, reliability, and lifespan of the equipment. With the development of industrial equipment towards higher speeds, lighter weight, and higher efficiency, centrifugal impellers typically bear high centrifugal loads, aerodynamic alternating loads, and vibration loads. High-speed impellers place higher demands on the specific strength, specific stiffness, fatigue performance, dynamic balance accuracy, and manufacturing consistency of materials. Although traditional metal impellers are technologically mature, they suffer from problems such as high density, high centrifugal stress at high speeds, limited corrosion resistance, and limitations in yield strength and specific strength, making it difficult to achieve significant improvements in mass, strength, and speed margin.

[0003] Carbon fiber reinforced resin matrix composites possess high specific strength, high specific stiffness, and designability, making them suitable for lightweight high-speed rotor structures. For open centrifugal impellers, which lack a front cover plate for constraint, the blades are directly connected to the discs or hub. The blade surfaces are complex, with significant variations in root thickness, and they simultaneously withstand centrifugal tension, blade bending-torsional coupling, aerodynamic alternating loads, and vibration loads during high-speed operation. If integral layup molding is used, the mold, layup, and demolding processes are all quite challenging. Modular split molding followed by integration is a feasible way to reduce manufacturing difficulty, but it creates splicing sections between adjacent modules. If these splicing sections are primarily connected by adhesive films, epoxy resin, or ordinary reinforcing prepregs, the interface mainly bears resin bonding and in-plane shear loads. At high speeds, this can easily lead to delamination, interlaminar crack propagation, or fatigue damage, making these splicing sections vulnerable to delamination, shear fatigue, and crack propagation.

[0004] The prior art document CN104791297A discloses a method for decomposing a centrifugal fan impeller into three independent parts: the impeller cover, the blades, and the impeller disc, and then using an epoxy resin system for curing and connecting them. This method can reduce the molding difficulty, but the joints still mainly rely on resin film bonding, lacking a thick-strength reinforcing member that spans the joint section. In high-speed composite impellers, it is still difficult to fully suppress interfacial delamination, interlaminar crack propagation, and shear fatigue failure.

[0005] Z-PIN thickness reinforcement technology can form fiber bridging in the thickness direction of composite laminates or joints to suppress interlaminar delamination and improve damage tolerance. However, existing Z-PIN technologies are mostly designed for flat laminates, T-joints, or skin-stringer joints, and have not developed specific manufacturing solutions for the circumferential modular splicing sections, high centrifugal loads at the blade roots, and impeller dynamic balance constraints of open composite centrifugal impellers.

[0006] In summary, there is an urgent need for a manufacturing method for reinforced open composite centrifugal impellers that can simultaneously meet the requirements of modular molding, interfacial peel strength, and high-speed rotor dynamic balance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes a reinforced open composite material centrifugal impeller and its manufacturing method, which includes:

[0008] S1: Prepare multiple slotted blade-disc modules 3, each slotted blade-disc module 3 including two circumferential blade sections and an upper disk sector 3c connecting the root of the circumferential blade section; the circumferential blade section is provided with a pin insertion area;

[0009] S2: Assemble multiple slotted blade-disc modules 3 in a circumferential direction, so that adjacent first slotted blade-disc modules 31 and second slotted blade-disc modules 32 are joined at the splicing section with the first splicing blade portion 31a and the second splicing blade portion 32b respectively.

[0010] S3: Lay reinforcing prepreg 5 at the splicing section, so that the reinforcing prepreg 5 fills the gap between the first splicing blade section 31a and the second splicing blade section 32b and covers the pin area; insert multiple Z-PINs 4 into the pin area, the axis of the Z-PINs 4 intersects the splicing section, and a part of the Z-PINs 4 is embedded in the first splicing blade section 31a of the first grooved blade-disc module 31, and another part is embedded in the second splicing blade section 32b of the second grooved blade-disc module 32;

[0011] S4: Pressurize and heat the grooved blade-disc module 3, the reinforcing prepreg 5 and Z-PIN4 to form the upper blade-disc assembly 2;

[0012] S5: Prepare the uncured hub-disc lower structure 1 and combine it with the blade-disc upper assembly 2 and cure it as a whole to obtain a reinforced open composite centrifugal impeller.

[0013] Preferably, in step S1, the pin insertion area is a region with multiple pin holes. During the preparation of the slotted blade-disc module, the slotted blade-disc module reserves pin holes before curing, or the pin holes are processed by micro-drilling, laser, ultrasound or water jet after the slotted blade-disc module is cured. The diameter of the pin holes is 1.02 to 1.30 times the diameter of Z-PIN 4.

[0014] Preferably, in step S3, multiple Z-PINs 4 inserted into the pin area form several Z-PIN rows along the height direction of the splicing section. Each Z-PIN 4 is generally arranged along the predetermined closing direction of the first grooved blade-disc module 31 and the second grooved blade-disc module 32. Some Z-PINs 4 are deflected in a plane perpendicular to the impeller rotation axis relative to the normal direction of the splicing section towards the predetermined interface main shear load direction. The deflection is limited to not hindering the first grooved blade-disc module 31 and the second grooved blade-disc module 32 from completing the assembly along the predetermined closing direction.

[0015] Furthermore, the diameter of Z-PIN4 is 0.2mm to 2.0mm, and the length is 1mm to 20mm; the center distance between the axes of adjacent Z-PIN4 in the same row is 1.5 to 10 times the diameter of Z-PIN4, and the row spacing between two adjacent rows of Z-PIN4 is 1.5 to 10 times the diameter of Z-PIN4.

[0016] Preferably, the Z-PIN 4 insertion density in the splicing section area near the root of the circumferential blade distribution or near the outer edge of the upper disk sector 3c is greater than the Z-PIN 4 insertion density in the middle region of the splicing section.

[0017] Preferably, Z-PIN 4 is one or more of carbon fiber composite needles, glass fiber composite needles, aramid fiber composite needles, ceramic fiber needles, or titanium alloy needles; the outer surface of Z-PIN 4 is a roughened surface, a resin-coated surface, or a surface with a spiral texture.

[0018] Preferably, the reinforcing prepreg 5 includes a 0-degree fiber layer laid along the blade span and positive and negative angle fiber layers laid at an angle relative to the blade span; the reinforcing prepreg 5 is disposed between the first spliced ​​blade section 31a and the second spliced ​​blade section 32b, the Z-PIN 4 passes through the reinforcing prepreg 5, and the two ends of the Z-PIN 4 are respectively embedded in the first spliced ​​blade section 31a and the second spliced ​​blade section 32b; after curing, the resin matrix of the reinforcing prepreg 5 covers the middle section of the Z-PIN 4 across the splicing section and fills the splicing gap.

[0019] Preferably, in step S5, before combining the blade-disc upper assembly 2 with the hub-disc lower structure 1, a reinforcing prepreg 5 or adhesive film is laid at the annular assembly interface between the two; the Z-PIN 4 is arranged in multiple rows along the annular assembly interface using a pin tooling, and a portion of the Z-PIN 4 is embedded in the blade-disc upper assembly 2, while another portion is embedded in the hub-disc lower structure 1, thereby forming a thick-strength reinforced connection across the interface between the two.

[0020] Preferably, in step S5, after the upper blade-disc assembly 2 and the lower hub-disc structure 1 are combined and cured as a whole, the circumferential blade portion of the obtained reinforced open composite centrifugal impeller is machined or finely repaired; the splicing section of the adjacent grooved blade-disc modules and the area where the annular assembly interface of the upper blade-disc assembly 2 and the lower hub-disc structure 1 is located are subjected to ultrasonic, industrial CT or impact testing to remove the reinforced open composite centrifugal impellers that do not meet the preset requirements; and the reinforced open composite centrifugal impellers are dynamically balanced.

[0021] A reinforced open composite centrifugal impeller includes an upper blade-disc assembly 2 and a lower hub-disc structure 1. The upper blade-disc assembly 2 and the lower hub-disc structure 1 are combined and connected. The upper blade-disc assembly 2 is formed by splicing multiple grooved blade-disc modules 3 in a circumferential direction. Each grooved blade-disc module 3 includes two circumferential side blade sections and an upper disk sector 3c connecting the roots of the circumferential blade sections. The splicing section of adjacent grooved blade-disc modules 3 has a thick-direction reinforced connection area formed by reinforcing prepreg 5 and multiple Z-PINs 4.

[0022] The beneficial effects of this invention are as follows:

[0023] First, the reinforced open composite centrifugal impeller manufactured by this invention uses Z-PINs spanning the joint sections of adjacent modules, which can form a bridging and pull-out energy dissipation mechanism when cracks initiate, suppressing the peeling propagation of the joint interface. Second, the Z-PINs are cured together with the reinforcing prepreg, so that the interface connection no longer relies solely on resin film bonding. The load-bearing method of the joint interface is transformed from simple resin bonding to joint load-bearing by resin matrix bonding, reinforcing fiber lay-up, and Z-PIN thickness bridging, which is suitable for bearing the composite tensile, shear, and vibration loads in high-speed impellers. Third, the Z-PINs are small-diameter distributed reinforcements, which can avoid the large openings, large mass eccentricity, and aerodynamic surface disturbances caused by traditional rivets or bolts. Fourth, the manufacturing scheme of this invention is compatible with modular prefabrication, secondary curing, and overall curing processes, and can retain the original manufacturing convenience. In summary, this invention can take into account the requirements of modular molding, interface peel strength, and high-speed rotor dynamic balance, improve the interlayer peel and shear resistance at the module joints, and is suitable for open composite centrifugal impellers under high-speed conditions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an open composite material centrifugal impeller structure according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the grooved blade-disc module structure according to an embodiment of the present invention;

[0026] Figure 3This is a magnified cross-sectional view of the splicing point of adjacent slotted blade-disc modules and the Z-PIN array in an embodiment of the present invention.

[0027] Figure 4 This is a top view of the splicing point between adjacent first grooved blade-disc modules and second grooved blade-disc modules according to an embodiment of the present invention.

[0028] In the diagram: 1. Hub-disc lower structure; 2. Blade-disc upper assembly; 3. Grooved blade-disc module; 3a. First circumferential blade section of a single grooved module; 3b. Second circumferential blade section of a single grooved module; 3c. Upper disk sector; 31. First grooved blade-disc module; 32. Second grooved blade-disc module; 31a. Spliced ​​blade section of the first grooved module; 32b. Spliced ​​blade section of the second grooved module; 4. Z-PIN; 5. Reinforcing prepreg. Detailed Implementation

[0029] 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. 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.

[0030] This invention proposes a reinforced open composite material centrifugal impeller and its manufacturing method, such as... Figure 1 As shown, the reinforced open composite centrifugal impeller includes a hub-disc lower structure 1 and a blade-disc upper assembly 2. The blade-disc upper assembly 2 is located above the hub-disc lower structure 1 and is integrally cured and connected to the hub-disc lower structure 1.

[0031] The overall approach to manufacturing a reinforced open composite centrifugal impeller is as follows: the upper working surface of the impeller is divided into multiple grooved blade-disc modules, and each grooved blade-disc module is prefabricated. When assembling adjacent modules, reinforcing prepreg is laid at the splicing section, and multiple rows of Z-PIN arrays are inserted. Then, a secondary curing process is performed to form the upper blade-disc assembly. When combining the upper blade-disc assembly with the lower hub-disc structure, reinforcing prepreg or adhesive film is laid at the annular assembly interface, and a Z-PIN array (a micro-rod-shaped reinforcement that spans the composite splicing section or assembly interface and is embedded in the composite components on both sides of the interface) is inserted across the interface. Finally, the entire assembly is cured to obtain the reinforced open composite centrifugal impeller.

[0032] Unlike simple epoxy resin bonding, this invention forms a reinforced connection zone at the splicing cross-section of adjacent grooved modules and at the annular assembly interface between the blade-disc upper assembly 2 and the hub-disc lower structure 1. This zone is jointly supported by resin matrix bonding, reinforcing fiber lay-up, and Z-PIN thick-axis bridging, so that the interface load is no longer borne solely by the adhesive layer or resin film. The manufacturing method specifically includes the following:

[0033] S1: Prepare multiple slotted blade-disc modules 3, each slotted blade-disc module 3 including two circumferential blade sections and an upper disk sector 3c connecting the root of the circumferential blade section; the circumferential blade section is provided with a pin insertion area.

[0034] The grooved blade-disc module 3 is fabricated using a grooved module molding die. Specifically, carbon fiber reinforced prepreg is laid inside the die cavity to integrally form two circumferential side blade sections (3a and 3b) and an upper disk sector 3c. A first heating and curing process is then performed, followed by demolding to obtain multiple cured, independent grooved blade-disc modules 3. Figure 2 As shown, the two circumferential blades are located on both sides of the upper disk sector.

[0035] The circumferential blade section is provided with a pin insertion area, which is an area with multiple pin holes. During the preparation of the slotted blade-disc module, the slotted blade-disc module is pre-reserved with pin holes before curing, or the pin holes are processed by micro-drilling, laser, ultrasonic or water jet after the slotted blade-disc module is cured. The diameter of the pin hole is 1.02 to 1.30 times the diameter of the Z-PIN.

[0036] S2: Assemble multiple slotted blade-disc modules 3 in a circumferential direction, so that adjacent first slotted blade-disc modules 31 and second slotted blade-disc modules 32 are joined at the splicing section with the first splicing blade portion 31a and the second splicing blade portion 32b respectively.

[0037] The first splicing blade portion 31a of the first grooved blade-disc module 31 and the second splicing blade portion 32b of the adjacent second grooved blade-disc module 32 can be spliced ​​at a designed angle. Multiple grooved blade-disc modules 3 are assembled in a circumferential direction, so that the adjacent first grooved blade-disc module 31 and second grooved blade-disc module 32 are connected at the splicing section with the first splicing blade portion 31a and the second splicing blade portion 32b respectively. The splicing section can be a straight section, a skewed section, a stepped section or a partially curved section.

[0038] Preferably, the splicing section is set at a position that avoids the thin, pointed areas of the leading and trailing edges of the blade, so as to allow for subsequent insertion of the Z-PIN and ensure the continuity of the blade's aerodynamic shape.

[0039] In some preferred embodiments of the present invention, before the adjacent grooved blade-disc modules are docked, the splicing section is treated with release agent removal, roughening, cleaning and drying; if necessary, plasma, flame or chemical activation treatment is performed to improve the bonding ability between the reinforcing prepreg 5 and the surface of the cured composite material.

[0040] S3: Lay reinforcing prepreg 5 at the splicing section, so that the reinforcing prepreg 5 fills the gap between the first splicing blade section 31a and the second splicing blade section 32b and covers the pin area; insert multiple Z-PINs into the pin area, the axis of the Z-PIN intersects the splicing section, and a part of the Z-PIN is embedded in the first splicing blade section 31a of the first grooved blade-disc module 31, and another part is embedded in the second splicing blade section 32b of the second grooved blade-disc module 32.

[0041] like Figure 3 As shown, reinforcing prepreg 5 is laid at the splicing section, so that the reinforcing prepreg 5 fills the gap between the first splicing blade section 31a and the second splicing blade section 32b and covers the pin area.

[0042] In some preferred embodiments of the present invention, the reinforcing prepreg 5 includes a 0-degree fiber layer laid along the blade spanwise and positive and negative angle fiber layers laid at an angle relative to the blade spanwise; wherein, the 0-degree direction is arranged along the blade spanwise or the main force transmission direction, and the positive and negative angle fiber layers are used to bear the interfacial shear load. The reinforcing prepreg 5 is disposed between the first spliced ​​blade section 31a and the second spliced ​​blade section 32b, and the Z-PIN passes through the reinforcing prepreg 5, with both ends of the Z-PIN embedded in the first spliced ​​blade section 31a and the second spliced ​​blade section 32b respectively; after curing in step S4, the resin matrix of the reinforcing prepreg 5 covers the middle section of the Z-PIN across the spliced ​​section and fills the splicing gap.

[0043] Using a pin fixture with guide holes arranged along a predetermined closing direction, multiple Z-PINs are inserted into the pin holes in the first splicing blade section 31a of the first slotted blade-disc module 31, so that one end of each Z-PIN is embedded in the first splicing blade section 31a, and the other end extends out of the first splicing blade section 31a and passes through the reinforcing prepreg 5. The corresponding pin holes in the second splicing blade section 32b of the second slotted blade-disc module 32 are aligned with the extended ends of each Z-PIN, and the second slotted blade-disc module 32 is moved along the predetermined closing direction until the extended ends of each Z-PIN enter the second splicing blade section 32b and the two slotted modules are joined. During the subsequent curing process, the Z-PINs are covered by the resin matrix of the reinforcing prepreg 5, thereby forming a reinforced connection area at the splicing section, which is supported by the resin matrix bonding, the reinforcing fiber layup, and the Z-PIN thickness bridging.

[0044] Figure 3 The enlarged partial cross-sectional view on the right is a frontal projection. In the figure, Z-PIN is represented by multiple rows of horizontal short rods located within the splicing material area. The reinforcing prepreg 5 and the split materials on both sides are shown in cross-section. Figure 3 A typical implementation with approximately parallel Z-PIN arrangement is shown; when at least a portion of the Z-PIN is skewed within the assembly tolerances, the skew direction lies in a plane perpendicular to the impeller rotation axis, and this slight skew does not affect... Figure 3 The figures are shown to scale.

[0045] In some preferred embodiments of the present invention, multiple Z-PINs inserted into the pin area form several Z-PIN rows along the height direction of the splicing section. Each Z-PIN is generally arranged along a predetermined closing direction of the first grooved blade-disc module 31 and the second grooved blade-disc module 32. At least some Z-PINs can be deflected relative to the normal direction of the splicing section towards a predetermined main interface shear load direction in a plane perpendicular to the impeller rotation axis, and this deflection does not hinder the closing assembly of adjacent modules. The remaining Z-PINs can be arranged along the normal direction of the splicing section or the predetermined closing direction. Each row of Z-PINs is spaced apart along the height direction of the splicing section to cover the main load-bearing area of ​​the splicing section.

[0046] The deflection angle is determined based on the Z-PIN length, pin hole diameter and depth, assembly gap of adjacent slotted modules, and predetermined closing path. It is limited to the point that the protruding end of the Z-PIN can enter the corresponding pin hole of the second splicing blade section 32b, and that bending or compression exceeding permissible limits does not occur during closing. By deflecting at least a portion of the Z-PIN towards the predetermined main interfacial shear load direction, the Z-PIN axis forms a load-bearing component in that load direction. When adjacent slotted modules exhibit a relative slippage tendency along the splicing section, the Z-PIN, in addition to bearing transverse shear and bending forces, also transmits loads through axial tension and interfacial bridging, thereby improving the shear bearing capacity of the splicing interface and suppressing the propagation of Type II or mixed-type interfacial cracks.

[0047] Figure 4 This indicates the reinforcing prepreg layer, Z-PIN arrangement, direction of the principal shear load at the interface, Z-PIN axis skew angle, and impeller rotation direction; such as Figure 4 As shown, in a top-view projection perpendicular to the impeller rotation axis, the first grooved blade-disc module 31 and the second grooved blade-disc module 32 are joined at the splicing section through the first splicing blade section 31a and the second splicing blade section 32b, respectively. The reinforcing prepreg 5 fills the splicing gap between the two in the form of a thin layer, and multiple rows of Z-PINs 4 span the reinforcing prepreg 5 and are respectively embedded in the composite material on both sides of the splicing section. Figure 4 middle, Indicates the direction of impeller rotation. and The Z-PIN axis represents the principal shear loads at the interface with opposite directions when adjacent modules tend to slip relative to each other along the splice section; the horizontal reference line extending from the splice section to one side of the interface represents the normal of the splice section. The acute angle relative to the normal reference line is the deflection angle. Therefore, the deflected Z-PIN axis forms a bearing component in the direction of the main shear load at the interface.

[0048] In some preferred embodiments of the present invention, the diameter of the Z-PIN is 0.2 mm to 2.0 mm, and the length is 1 mm to 20 mm; the center distance between adjacent Z-PIN axes in the same row is 1.5 to 10 times the Z-PIN diameter, and the row spacing between two adjacent rows of Z-PINs is 1.5 to 10 times the Z-PIN diameter. Preferably, the center distance between adjacent Z-PINs in the same row and the row spacing between two adjacent rows of Z-PINs are both 1 mm to 6 mm, and the selected center distance and row spacing should also simultaneously meet the ratio requirement of 1.5 to 10 times the Z-PIN diameter; the specific values ​​are determined according to the Z-PIN diameter, splicing section size, local load level, and pin insertion process. The Z-PIN insertion density in the splicing section area near the root of the circumferential side blade distribution or near the outer edge of the upper disk sector 3c is greater than the Z-PIN insertion density in the middle area of ​​the splicing section, that is, a higher arrangement density is adopted in the stress concentration area; preferably, the center distance or row spacing in the same row can be appropriately increased in the low load area to control the additional mass while improving the interface strength.

[0049] In some preferred embodiments of the present invention, the Z-PIN is one or more of carbon fiber composite needles, glass fiber composite needles, aramid fiber composite needles, ceramic fiber needles or titanium alloy needles; preferably, the Z-PIN adopts a carbon fiber composite needle compatible with the impeller body resin system to reduce density difference and reduce dynamic balance correction; the outer surface of the Z-PIN is a roughened surface, a resin film coated surface or a surface with spiral texture.

[0050] S4: Pressurize and heat the grooved blade-disc module 3, the reinforcing prepreg 5 and the Z-PIN to form the upper blade-disc assembly 2.

[0051] Vacuum bagging, molding, or autoclave pressure is applied to the slotted blade-disc module 3, reinforcing prepreg 5, and Z-PIN, and the resin system of the reinforcing prepreg 5 is heated and cured (second curing). During the curing process, the resin of the reinforcing prepreg 5 flows and wets the gaps around the Z-PIN. After curing, a reinforced connection area is formed by adjacent modules, reinforcing prepreg 5, and Z-PIN, resulting in a structurally complete blade-disc upper assembly 2.

[0052] The present invention uses multiple rows of Z-PINs arranged along a predetermined closing direction and deflected toward the predetermined interface main shear load direction to form a thick-axis bridging of the splicing section of adjacent modules; when the interface cracks extend along the splicing section, the Z-PINs generate energy dissipation through bridging, stretching, pull-out or fracture; at the same time, the reinforcing prepreg (5) coats the Z-PINs and forms a continuous resin matrix during the secondary curing process, thereby improving the interlayer peel strength and shear fatigue resistance of the splicing section.

[0053] S5: Prepare the uncured hub-disc lower structure and combine it with the blade-disc upper assembly 2 and cure it as a whole to obtain a reinforced open composite centrifugal impeller.

[0054] Using the impeller final forming bottom mold, uncured carbon fiber reinforced prepreg for forming the hub-disc lower structure 1 is laid in the bottom mold to form the uncured hub-disc lower structure.

[0055] A reinforcing prepreg 5 or film is laid at the annular assembly interface between the uncured hub-disc lower structure and the blade-disc upper assembly 2, and the blade-disc upper assembly 2 is positioned on the hub-disc lower structure 1 for assembly, with the reinforcing prepreg 5 overlapping at the annular assembly interface between the two.

[0056] In some preferred embodiments of the present invention, before laying the reinforcing prepreg 5 or adhesive film at the annular assembly interface of the blade-disc upper assembly 2 and the hub-disc lower structure 1, the upper surface of the hub-disc lower structure 1 and the lower surface of the blade-disc upper assembly 2 to be joined are roughened, cleaned and activated.

[0057] Before or after assembly, the Z-PIN is arranged in multiple rows along the annular assembly interface using a pin tooling, and a portion of the Z-PIN is embedded in the upper blade-disc assembly 2, while another portion is embedded in the lower hub-disc structure 1, thereby forming a thick-strength reinforced connection across the interface between the two.

[0058] Z-PIN is preferably inclined at a small angle along the impeller axis or relative to the impeller axis and arranged symmetrically in the circumferential direction to avoid introducing obvious mass eccentricity; then a third overall curing is performed to combine the blade-disc upper assembly 2 and the hub-disc lower structure 1 into an impeller whole, resulting in a reinforced open composite centrifugal impeller.

[0059] In some preferred embodiments of the present invention, for the impeller blank obtained after overall curing and demolding, the leading edge, trailing edge, hub hole and outer circle of the blade are machined or finely repaired; the splicing section of the adjacent slotted module and the area where the annular assembly interface of the blade-disc upper assembly 2 and the hub-disc lower structure 1 is located are subjected to ultrasonic, industrial CT or knocking tests, so as to check the insertion state of Z-PIN (4) and interface porosity, delamination or debonding defects, and the impeller blank is judged according to the preset acceptance standard; the impeller blank that does not meet the preset acceptance standard is re-inspected or scrapped, and the impeller blank that meets the preset acceptance standard is dynamically balanced to obtain the finished reinforced open composite centrifugal impeller.

[0060] The present invention also proposes a reinforced open composite centrifugal impeller, which is manufactured according to the above-described manufacturing method. It includes an upper blade-disc assembly 2 and a lower hub-disc structure 1. The upper blade-disc assembly 2 and the lower hub-disc structure 1 are integrally cured and connected. The upper blade-disc assembly 2 is obtained by splicing multiple grooved blade-disc modules 3 in a circumferential direction. Each grooved blade-disc module 3 includes two circumferential side blade sections and an upper disk sector 3c connecting the roots of the circumferential blade sections. The splicing section of adjacent grooved blade-disc modules 3 has a thick-direction reinforced connection area formed by reinforcing prepreg 5 and multiple Z-PINs.

[0061] In summary, this invention decomposes the upper structure of the impeller into multiple easily manufactured grooved blade-disc modules, and introduces Z-PINs and reinforcing prepregs 5 to be cured together at the splicing sections of adjacent modules and at the annular assembly interface between the upper blade-disc assembly 2 and the lower hub-disc structure 1 to form a reinforced connection area, which has the following advantages:

[0062] (1) Improve the interlayer anti-peeling ability of the splicing section and the upper and lower assembly interface. The Z-PIN spans the splicing area of ​​the first splicing blade section 31a and the second splicing blade section 32b, and can further span the annular assembly interface of the blade-disc upper assembly 2 and the hub-disc lower structure 1; when the interface cracks initiate or extend, the Z-PIN can form a bridging, pull-out and fracture energy dissipation mechanism, thereby suppressing the peeling extension of the splicing interface and the annular assembly interface.

[0063] (2) Improve shear fatigue resistance. Multiple Z-PINs at the splicing section of adjacent slotted modules are generally arranged along the predetermined closing direction, and at least some Z-PINs are deflected towards the predetermined main shear load direction of the interface. When the splicing section is subjected to centrifugal tension, blade bending-torsional coupling and aerodynamic alternating load, they can provide shear constraint through transverse shear, bending and axial bridging. The Z-PINs arranged at the annular assembly interface between the blade-disc upper assembly 2 and the hub-disc lower structure 1 can improve the peel resistance and shear resistance of the upper and lower structures, which is more suitable for high-speed conditions than simple adhesive film or epoxy resin bonding.

[0064] (3) Avoid large openings and mass eccentricity caused by mechanical connections. Z-PIN is a small-diameter distributed reinforcement component. Compared with rivet, bolt or snap ring connection, it does not require large openings on the composite blade body, which can reduce stress concentration and the difficulty of dynamic balance correction.

[0065] (4) Maintain the aerodynamic shape of the open impeller. The Z-PIN end can be lower than or flush with the aerodynamic surface of the blade. After curing, the blade surface is made continuous by fine finishing to avoid significant aerodynamic disturbance.

[0066] (5) Reduce the manufacturing difficulty of complex open impellers. The grooved blade-disc module 3 can be prefabricated separately, reducing the difficulty of overall layup, mold and demolding; and the Z-PIN and reinforcing prepreg 5 are used to enhance the splicing interface of adjacent modules and the annular assembly interface of the upper and lower structures, thereby improving the structural reliability of the modular impeller under high-speed conditions.

[0067] (6) In this invention, Z-PIN thick reinforcement and reinforcing prepreg are further set at the splicing of adjacent slotted modules and at the annular assembly interface of blade-disc upper assembly 2 and hub-disc lower structure 1, so that the interface bearing mode is changed from simple resin bonding to resin matrix bonding, reinforcing fiber layup and Z-PIN thick bridging bearing, which has clear structural and process differences.

[0068] The above-described embodiments further illustrate the purpose, technical solution, and advantages of the present invention. It should be understood that the above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a reinforced open composite centrifugal impeller, characterized in that, Includes the following steps: S1: Prepare multiple slotted blade-disc modules (3), each slotted blade-disc module (3) includes two circumferential blade sections and an upper disk sector (3c) connecting the root of the circumferential blade section; the circumferential blade section is provided with a pin area; S2: Assemble multiple slotted blade-disc modules (3) in the circumferential direction, so that the adjacent first slotted blade-disc module (31) and second slotted blade-disc module (32) are connected at the splicing section with the first splicing blade section (31a) and the second splicing blade section (32b), respectively. S3: Lay reinforcing prepreg (5) at the splicing section, so that the reinforcing prepreg (5) fills the gap between the first splicing blade section (31a) and the second splicing blade section (32b) and covers the pin area; insert multiple Z-PINs (4) into the pin area, the axis of the Z-PIN (4) intersects the splicing section, and a part of the Z-PIN (4) is embedded in the first splicing blade section (31a) of the first grooved blade-disc module (31), and the other part is embedded in the second splicing blade section (32b) of the second grooved blade-disc module (32); S4: The grooved blade-disc module (3), reinforcing prepreg (5) and Z-PIN (4) are pressurized and heated to form the upper blade-disc assembly (2). S5: Prepare an uncured hub-disc lower structure (1) and combine it with the blade-disc upper assembly (2) and cure it as a whole to obtain a reinforced open composite centrifugal impeller.

2. The method for manufacturing a reinforced open composite centrifugal impeller according to claim 1, characterized in that, In step S1, the pin insertion area is a region with multiple pin insertion holes. During the preparation of the slotted blade-disc module, the slotted blade-disc module reserves pin insertion holes before curing, or the pin insertion holes are processed by micro-drilling, laser, ultrasound or water jet after the slotted blade-disc module is cured. The diameter of the pin insertion hole is 1.02 to 1.30 times the diameter of Z-PIN (4).

3. The method for manufacturing a reinforced open composite centrifugal impeller according to claim 1, characterized in that, In step S3, multiple Z-PINs (4) inserted into the pin area form several Z-PIN rows along the height direction of the splicing section. Each Z-PIN (4) is generally arranged along the predetermined closing direction of the first grooved blade-disc module (31) and the second grooved blade-disc module (32). Some Z-PINs (4) are deflected in the plane perpendicular to the impeller rotation axis relative to the normal direction of the splicing section towards the predetermined interface main shear load direction. The deflection is limited to not hindering the first grooved blade-disc module (31) and the second grooved blade-disc module (32) from completing the assembly along the predetermined closing direction.

4. The method for manufacturing a reinforced open composite centrifugal impeller according to claim 3, characterized in that, The diameter of the Z-PIN (4) is 0.2 mm to 2.0 mm and the length is 1 mm to 20 mm; the center distance between the axes of adjacent Z-PIN (4) in the same row is 1.5 to 10 times the diameter of the Z-PIN (4), and the row spacing between two adjacent rows of Z-PIN (4) is 1.5 to 10 times the diameter of the Z-PIN (4).

5. The method for manufacturing a reinforced open composite centrifugal impeller according to claim 1, characterized in that, The Z-PIN (4) insertion density in the splicing section area near the root of the circumferential blade distribution or near the outer edge of the upper disk sector (3c) is greater than the Z-PIN (4) insertion density in the middle region of the splicing section.

6. The method for manufacturing a reinforced open composite centrifugal impeller according to claim 1, characterized in that, The Z-PIN (4) is one or more of carbon fiber composite needles, glass fiber composite needles, aramid fiber composite needles, ceramic fiber needles or titanium alloy needles; the outer surface of the Z-PIN (4) is a roughened surface, a resin film coated surface or a surface with a spiral texture.

7. The method for manufacturing a reinforced open composite centrifugal impeller according to claim 1, characterized in that, The reinforcing prepreg (5) includes a 0-degree fiber layer laid along the blade span and positive and negative angle fiber layers laid at an angle relative to the blade span; the reinforcing prepreg (5) is disposed between the first spliced ​​blade section (31a) and the second spliced ​​blade section (32b), and the Z-PIN (4) passes through the reinforcing prepreg (5), with the two ends of the Z-PIN (4) respectively embedded in the first spliced ​​blade section (31a) and the second spliced ​​blade section (32b); after curing, the resin matrix of the reinforcing prepreg (5) covers the Z-PIN (4) across the middle section of the splicing section and fills the splicing gap.

8. The method for manufacturing a reinforced open composite centrifugal impeller according to claim 1, characterized in that, In step S5, before combining the blade-disc upper assembly (2) with the hub-disc lower structure (1), a reinforcing prepreg (5) or adhesive film is laid at the annular assembly interface between the two. The Z-PIN (4) is arranged in multiple rows along the annular assembly interface using a pin tooling, and a part of the Z-PIN (4) is embedded in the blade-disc upper assembly (2), and another part is embedded in the hub-disc lower structure (1), thereby forming a thick-strength reinforced connection across the interface between the two.

9. The method for manufacturing a reinforced open composite centrifugal impeller according to claim 1, characterized in that, In step S5, after combining and curing the upper blade-disc assembly (2) and the lower hub-disc structure (1), the circumferential blades of the obtained reinforced open composite centrifugal impeller are machined or finely repaired; the splicing section of the adjacent grooved blade-disc module and the area of ​​the annular assembly interface between the upper blade-disc assembly (2) and the lower hub-disc structure (1) are subjected to ultrasonic, industrial CT or impact testing to remove the reinforced open composite centrifugal impellers that do not meet the preset requirements; and the reinforced open composite centrifugal impellers are dynamically balanced.

10. A reinforced open composite material centrifugal impeller, characterized in that, The reinforced open composite centrifugal impeller is manufactured by the manufacturing method described in any one of claims 1 to 9, comprising a blade-disc upper assembly (2) and a hub-disc lower structure (1), wherein the blade-disc upper assembly (2) and the hub-disc lower structure (1) are integrally cured and connected, the blade-disc upper assembly (2) is obtained by splicing multiple grooved blade-disc modules (3) in the circumferential direction, each grooved blade-disc module (3) includes two circumferential side blade sections and an upper disk sector (3c) connecting the root of the circumferential blade section; the splicing section of adjacent grooved blade-disc modules (3) has a thick-direction reinforced connection area formed by reinforcing prepreg (5) and multiple Z-PINs (4).

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