A method of forming a composite material blade tip

Abstract

This invention relates to the field of aircraft rotor blade processing and forming technology, and particularly to a method for forming the edge of a composite material rotor blade, comprising the following steps: S1: Unfolding and laying out a thin-walled sheet material for making the blade edge to obtain the maximum length and width; then cutting the thin-walled sheet material according to the required contour; S2: Performing a first stamping and bending of the cut thin-walled sheet material through a stamping die one; S3: Performing a second stamping and bending of the first stamping and bending of the thin-walled sheet material through a stamping die two to obtain a pre-edge structure with nearly equal width on both curved surfaces; S4: Cutting off the excess portion of the leeward edge; S5: Flanging the edge at the blade tip using a stamping die three. The edge forming method in this solution produces edge wall thickness that is uniform, low in cost, has high surface fit, and excellent mechanical properties, making it suitable for mass production.

Description

Technical Field

[0001] This invention relates to the field of aircraft propeller blade processing and forming technology, and in particular to a method for edge forming of composite material propeller blades. Background Technology

[0002] The rotor blade is an important component of the helicopter rotor system. The leading edge of the rotor blade is an important protective structure in the helicopter rotor blade. Its main functions include: protecting the rotor blade from air erosion when rotating at high speed, preventing the blade from being damaged by delamination, protecting the composite material body of the rotor blade and the anti-icing heating components from being hit by dust, gravel and other foreign objects, so as to improve the overall air erosion and foreign object impact resistance of the composite material rotor blade.

[0003] Currently, helicopter rotor blades are typically made of composite materials. The leading edge edging of helicopter rotor blades is mostly made of stainless steel or titanium alloy. Stainless steel is generally formed by cold stamping, while titanium alloy must be formed by hot forming. The main problems in forming titanium alloy blades are as follows: 1) Hot forming can achieve integral forming of complex thin-walled titanium alloy components, but due to the limitations of the size of the hot forming equipment platform, it is difficult for existing equipment to directly form the entire blade edging; 2) Titanium alloy is relatively soft, making it difficult to form thin-walled parts using traditional stainless steel edging bending machines or stamping; 3) There are also problems such as thin edge thickness and low strength, which makes the rotor blade susceptible to damage or even breakage when subjected to impacts from foreign objects such as birds or hail during normal operation at high speeds.

[0004] To avoid the above problems, nickel alloy blade edging has emerged in the existing technology, but the following problems still exist: 1) Existing edging is mostly electroplated nickel, which is expensive, the material is mostly pure nickel and is prone to producing metal impurities, and too little boric acid content and too low plating bath temperature will cause pinholes (pitting) in the electroplated nickel layer, resulting in defects in the metal body; 2) The wall thickness of the electroplated nickel forming curved surface is uneven, which is easy to interfere with the mounting surface of the edging groove reserved in the original mold, and the secondary machining of the curved surface is difficult; 3) At present, the edging substrate can also be printed by 3D printing technology, but this process technology has high equipment requirements, low production efficiency, and the prepared edging has incomplete fusion, pores, and unfused particles, and its strength does not meet the aerospace requirements.

[0005] In summary, designing a composite material blade edge protector with uniform wall thickness, high strength, low cost, and easy molding is an urgent problem to be solved. Summary of the Invention

[0006] To solve the above problems, the present invention provides a method for edge forming of composite material blades.

[0007] To achieve the above objectives, the present invention proposes the following technical solution: a method for edge-wrapping forming of composite material blades, comprising the following steps:

[0008] S1: The thin-walled sheet material used to make the blade edging is unfolded and laid flat using 3D digital modeling software to obtain the maximum length and width; then the thin-walled sheet material is cut according to the actual required contour using a laser cutting machine;

[0009] S2: The cut thin-walled sheet is stamped and bent once through a stamping die;

[0010] S3: The thin-walled sheet material that has been stamped and bent once is subjected to a second stamping and bending through a stamping die to obtain a pre-edge structure with non-uniform widths on both sides, including PS bread edge and SS bread edge.

[0011] S4: Use CNC 3D cutting to remove excess parts from the edges of SS bread;

[0012] S5: The connection between the PS and SS bread edges is stamped and bent using stamping die three to complete the flanging of the blade tip edge, thus completing the blade edge production.

[0013] Furthermore, the thin-walled plate in S1 is made of a nickel-based alloy.

[0014] Furthermore, during a single stamping bend in S2, the bending angle is 50°-60°.

[0015] Furthermore, during the secondary stamping and bending in S2, the bending angle follows the shape.

[0016] Furthermore, the blade sheath length in the S5 is 550mm-650mm.

[0017] Furthermore, the flange height of the edge banding in S5 is 0.2mm-0.3mm, and the flange gap is filled with epoxy resin.

[0018] Furthermore, the length of the flange notch is 1.5mm-2mm.

[0019] Furthermore, the thickness of the blade sheath in S5 is 0.3-0.5 mm.

[0020] Furthermore, in S5, after the blade edging is manufactured, the edging is bonded to the blade body with a prepreg film and then cured and formed by a molding machine.

[0021] Furthermore, the prepreg film is 0.2-0.3 mm thick.

[0022] The beneficial effects of this invention are:

[0023] 1. In this invention, the blade edge of the nickel alloy structure is a non-uniform width structure, that is, the width of the PS edge is greater than the width of the SS edge. Under the premise of ensuring the strength of the PS surface (windward side) of the blade body, more installation space can be reserved for the SS surface (leeward side) of the blade body to install other components. At the same time, it can save materials, prevent detachment, and ensure firm adhesion.

[0024] 2. The blade edge in this invention is formed by three sets of stamping dies (stamping die one, stamping die two, and stamping die three) through three stamping processes, combined with three-dimensional machining technology. The curved surface forming efficiency is high and wrinkles are not easily generated.

[0025] 3. The blade edge banding in this invention has excellent mechanical properties, the edge banding curved surface fits closely, the adhesive layer is uniform, the edge banding bonding strength is high, the cost is low, the molding wall thickness is uniform, and it is suitable for mass production. Attached Figure Description

[0026] Figure 1 This is a process flow diagram of the edge-binding forming method provided in the embodiments of the present invention.

[0027] Figure 2 This is a schematic diagram of the structure of a stamping die provided in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the structure of the stamping die II provided in an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of the structure of the stamping die three provided in the embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the structure of the blade edge mounting seat after it is attached to the blade body according to an embodiment of the present invention, wherein a is a bottom view, b is a front view, and c is a top view.

[0031] Figure reference numerals: 1. Blade body; 2. Thin-walled plate; 3. Blade edge; 4. PS edge; 5. SS edge; 6. Flanged edge; 7. Upper mold 1; 8. Lower mold 1; 9. Upper mold 2; 10. Lower mold 2; 11. Upper mold 3; 12. Lower mold 3. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-5 The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation thereof.

[0033] A method for edge-wrapping forming of composite material blades, such as Figure 1 As shown, it includes the following steps:

[0034] S1: Using 3D digital modeling software, the thin-walled sheet 2 used to make the blade edging 3 is unfolded and laid flat to obtain the maximum length and width, which can save materials and reduce costs. The maximum length is as follows: Figure 1 As shown in L1, the maximum width is as follows Figure 1 As shown in H1; then the thin-walled plate 2 is cut according to the actual required contour by a laser cutting machine; wherein the thin-walled plate 2 is made of nickel-based alloy.

[0035] S2: The cut thin-walled sheet 2 is punched and bent once using a stamping die; the bending angle is 50°-60°, preferably 55°; the stamping die is as follows: Figure 2 As shown, the die includes an upper die 7 and a lower die 8. The cut thin-walled sheet 2 is placed on the lower die 8, and then the upper die 7 is pressed onto the lower die 8 to complete one stamping and bending operation. The stamping die has a narrow-edge die bevel and a wide-edge die bevel. The bevel smoothly transitions from the root of the bevel to the tip of the bevel along the curved surface of the blade body. The bevel ensures that the resin overflowing after the bevel molding can fill the bevel. After installation, there will be no step difference between the bevel and the composite material blade body at the bevel, which can prevent the generation of reverse airflow.

[0036] S3: The thin-walled sheet 2, which has been bent in one stamping, is subjected to a second stamping and bending using a second stamping die to obtain a pre-embedded structure with non-uniform widths on both sides, including PS bread edge 4 and SS bread edge 5, with the bending angle following the shape; the second stamping die is as follows... Figure 3 As shown, it includes an upper die 2 9 and a lower die 2 10. The thin-walled sheet 2 after one stamping and bending is placed on the lower die 2 10, and then the upper die 2 9 is pressed on the lower die 2 10 to complete the second stamping and bending.

[0037] S4: The excess portion of the SS bread edge 5 is cut off using CNC 3D cutting. After cutting, the width of the SS bread edge 5 is 10-12mm, and the width of the PS bread edge 4 is 45-54mm. That is, the blade edge 3 has a non-uniform width design. The wide side is the windward PS side of the blade body 1, and the narrow side is the leeward SS side of the blade body 1. The width of the windward side is about four times that of the leeward side. The windward side is responsible for bearing the main load, effectively bearing the stress surface while achieving effective weight reduction. The density of nickel-based alloy is 8.9-9.2g / cm3, while the density of general composite materials such as high-performance carbon fiber composites is about 1.6-2.0g / cm3. Nickel-based alloy has a higher density, resulting in a 40% weight reduction compared to the uniform width design of the nickel-based alloy edge itself. This is of great significance for overall weight control when nickel-based alloy edge is used extensively on aerospace blades.

[0038] S5: The connection between the PS bread edge 4 and the SS bread edge 5 is stamped and bent using a stamping die three to complete the flanging 6 of the blade tip edge, thus completing the blade edge 3. The length of the blade edge 3 is 550mm-650mm, preferably 600mm; the height of the flanging 6 of the blade edge 3 is 0.2mm-0.3mm, and the notch of the flanging 6 is filled with epoxy resin; the length of the notch of the flanging 6 is 1.5mm-2mm; the thickness of the blade edge 3 is 0.3-0.5mm. The edged blade tip area adopts a flanging design to ensure that the blade tip is not thrown off under harsh operating conditions such as wind and sand. The bending angle at the bottom of the edge is close to 32.1°, which transitions evenly to 24.9° at the blade tip, protecting the blade tip of the composite material blade from damage. Edge banding also solves the technical challenge of right-angle wrinkles during stamping and forming of nickel alloys with high hardness. It expands the protection range for blade tips, making the entire edge banding prevent detachment. The blade tip is filled with a pre-impregnated adhesive film, allowing the resin to overflow and fill the flange gap. The overall structure has stable strength, good process feasibility, and fewer wrinkle defects. The inner surface of the edge banding can be sandblasted to further improve bonding strength. (Stamping Die, Sanru) Figure 5 As shown, it includes upper mold 3 11 and lower mold 3 12.

[0039] In S5, after the blade edging 3 is made, the edging is bonded to the blade body 1 with a prepreg film and then cured by a molding machine. The prepreg film is 0.2-0.3mm thick.

[0040] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0041] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for edge-wrapping forming of composite material blades, characterized in that, Includes the following steps: S1: The thin-walled plate (2) used to make the blade edging (3) is unfolded and laid flat using three-dimensional digital modeling software to obtain the maximum length and width; then the thin-walled plate (2) is cut according to the actual required contour using a laser cutting machine; S2: The cut thin-walled sheet (2) is punched and bent once through a stamping die; S3: The thin-walled sheet (2) that has been stamped and bent once is subjected to a second stamping and bending through the second stamping die to obtain a pre-wrapped edge structure with non-equal width on both sides of the curved surface, including PS bread edge (4) and SS bread edge (5). S4: Cut off the excess part of the SS bread crust (5) by CNC three-dimensional cutting; S5: The connection between PS bread edge (4) and SS bread edge (5) is stamped and bent by stamping die three to complete the flanging (6) of the blade tip edge, and the blade edge (3) is completed.

2. The method for edge-wrapping forming of composite material blades according to claim 1, characterized in that, The thin-walled plate (2) described in S1 is made of nickel-based alloy.

3. The method for edge-wrapping forming of composite material blades according to claim 2, characterized in that, When performing a single stamping bend in S2, the bending angle is 50°-60°.

4. The method for edge-wrapping forming of composite material blades according to claim 3, characterized in that, When performing secondary stamping and bending in S2, the bending angle follows the shape.

5. The method for edge-forming composite material blades according to claim 4, characterized in that, The length of the blade sheath (3) in S5 is 550mm-650mm.

6. The method for edge-forming composite material blades according to claim 5, characterized in that, The height of the flange (6) of the edge banding in S5 is 0.2mm-0.3mm, and the gap of the flange (6) is filled with epoxy resin.

7. The method for edge-forming composite material blades according to claim 6, characterized in that, The notch length of the flange (6) is 1.5mm-2mm.

8. The method for edge-forming composite material blades according to claim 7, characterized in that, The thickness of the blade sheath (3) in S5 is 0.3-0.5mm.

9. The method for edge-forming composite material blades according to claim 8, characterized in that, In S5, after the blade edge (3) is made, the blade edge (3) is bonded to the blade body (1) with a prepreg film and then cured by a molding machine.

10. The method for edge-forming composite material blades according to claim 9, characterized in that, The prepreg film has a thickness of 0.2-0.3 mm.

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