Automatic inclinator guide cylinder and preparation method thereof

Abstract

The invention provides an automatic inclinator guide cylinder and a preparation method thereof, and belongs to the technical field of helicopter transmission systems. The automatic inclinator guide cylinder provided by the invention is made of a carbon fiber composite material; the carbon fiber composite material comprises carbon fibers and an organic modified material; the organic modified material comprises one or more of epoxy resin, bismaleimide and polyaryletherketone. The carbon fiber composite material comprises the nonmetal carbon fiber and the organic modified material, the carbon element of the carbon fiber is extremely high in chemical stability and does not react with rainwater, the composite material does not have electrochemical activity of metal, and microbattery corrosion or oxygen absorption corrosion cannot occur. The organic modified material has excellent water barrier property, and transient wetting is only formed on the surface; moreover, solution loss or falling is avoided, and the integrity of the core structure is not affected.

Description

Technical Field

[0001] This invention belongs to the technical field of helicopter transmission systems, specifically relating to an automatic swashplate guide tube and its preparation method. Background Technology

[0002] The swashplate guide tube, a key component of the helicopter's transmission system, acts as a bridge connecting the fuselage control system and the rotor system. It translates the pilot's control commands (longitudinal, lateral, collective pitch) into changes in rotor blade angles, ultimately controlling the helicopter's climb, roll, and yaw. Traditional swashplate guide tubes are typically made of aluminum alloy. The swashplate guide tube operates in a rainy environment; rainwater (especially long-term accumulated rainwater) is not pure water and can dissolve CO2, SO2, and NO from the air. x Gases such as these create a weakly acidic environment (pH value is usually 5.6~6.5, and acid rain can be as low as pH value <4). At the same time, they may carry impurities such as dust and salt (rainwater in coastal areas has a higher salt content). These factors can directly trigger the electrochemical corrosion of aluminum alloys.

[0003] Although aluminum alloys have a natural oxide film (Al2O3) on their surface, the weak acidity of rainwater slowly dissolves this oxide film, exposing the fresh aluminum substrate. At this point, the aluminum substrate (anode) and elements such as Cu and Mg in the alloy (cathode) form a "micro-battery" under the action of rainwater (electrolyte), resulting in oxygen corrosion. The generated aluminum hydroxide is loose and easily detaches, further exposing the new substrate, forming a cycle of "corrosion-detachment-re-corrosion." If the rainwater contains salt, Cl... - This accelerates the penetration of the oxide film, leading to more severe pitting corrosion and causing a thinning of the aluminum alloy cross-section and a decrease in strength in the short term. Long-term corrosion of the aluminum alloy by rainwater results in cross-sectional thinning and the initiation of internal microcracks. Therefore, the guide cylinders of automatic tilting devices commonly made of aluminum alloys have poor corrosion resistance. Summary of the Invention

[0004] The purpose of this invention is to provide an automatic tilting guide tube and its preparation method. The carbon fiber composite automatic tilting guide tube of this invention has a significant advantage in corrosion resistance compared with the traditional aluminum alloy automatic tilting guide tube.

[0005] To achieve the objectives of this invention, the following technical solutions are provided: An automatic tilter guide tube includes a cylindrical section (1) and a conical section (3) connecting the cylindrical section (1), wherein the free end of the conical section (3) includes a convex ring (31) extending outward around the circumference, characterized in that the automatic tilter guide tube is made of carbon fiber composite material. The carbon fiber composite material includes carbon fiber and organic modified materials; the organic modified materials include one or more of epoxy resin, bismaleimide and polyaryletherketone.

[0006] Preferably, the carbon fiber volume content in the carbon fiber composite material is 48-55%.

[0007] Preferably, the epoxy resin comprises a tetrafunctional glycidyl amine or a toughened epoxy resin prepreg.

[0008] Preferably, the carbon fiber has a single filament diameter of 7μm±0.2, a tensile strength ≥5GPa, and an elastic modulus ≥294GPa; The density of the carbon fiber composite material is 1.5~1.65 g / cm³. 3 .

[0009] Preferably, the convex ring (31) is provided with screw holes, and the distance between every two screw holes is 80~130mm.

[0010] Preferably, the transition fillet of the conical cylinder section (3) is ≥5mm; the distance between the stud hole and the outermost edge of the convex ring (31) is ≥2 times the diameter of the stud hole.

[0011] Preferably, the outer diameter of the cylindrical section (1) is 143±0.2mm, the inner diameter is 138±0.2mm, the height is 225±0.2mm, and the wall thickness is 5±0.2mm; The outer diameter of the free end of the conical cylinder section (3) is 143~190mm, and the inner diameter is 138~185mm; the height of the conical cylinder section (3) is 85±0.2mm, and the wall thickness is 5±0.2mm.

[0012] The present invention also provides a method for preparing the automatic tilter guide tube described in the above technical solution, comprising the following steps: Carbon fiber composite material is laid layer by layer on the surface of the automatic tilter guide cylinder mold, and the automatic tilter guide cylinder is obtained after molding.

[0013] Preferably, the carbon fiber composite material has a single-layer thickness of 0.1~0.2mm and a number of layers of 30~50.

[0014] Preferably, the molding is hot pressing; the hot pressing temperature is 100~140℃, the pressure is 0.5~1.0MPa, and the heat and pressure holding time is 1~3 h.

[0015] This invention provides an automatic tilting guide tube, comprising a cylindrical section (1) and a conical section (3) connecting the cylindrical section (1). The free end of the conical section (3) includes a convex ring (31) extending outward around the circumference. The automatic tilting guide tube is characterized by being made of carbon fiber composite material; the carbon fiber composite material includes carbon fiber and organic modified materials; the organic modified materials include one or more of epoxy resin, bismaleimide, and polyaryletherketone. The carbon fiber composite material of this invention comprises non-metallic carbon fiber and organic modified materials. The carbon element of the carbon fiber has extremely high chemical stability and does not react with rainwater. Furthermore, the composite material lacks the electrochemical activity of metals and will not experience "micro-battery corrosion" or "oxygen absorption corrosion." The organic modified materials themselves possess excellent "water barrier properties," making it difficult for rainwater to penetrate the material's interior, only causing temporary surface wetting. Even with prolonged rain exposure, the resin will only undergo very slight "surface hydrolysis" (the hydrolysis rate of ordinary epoxy resin in a rainwater environment is <5% over 10 years), and will not experience "dissolution" or "detachment," thus maintaining the integrity of the core structure. Therefore, carbon fiber resin-based composite materials exhibit almost no significant degradation in mechanical properties even after long-term exposure to rainwater, demonstrating excellent corrosion resistance. Furthermore, the carbon fiber composite automatic tilter guide cylinder of this invention overcomes the specific strength bottleneck by replacing carbon fiber material, achieving a weight reduction of over 40% and addressing the need for lightweighting; it also improves the corrosion resistance of the guide cylinder, extending the replacement cycle in marine environments to over 8 years and reducing maintenance costs.

[0016] Furthermore, the carbon fiber composite materials of this invention with different modified materials can cover all scenarios such as "normal temperature-high temperature" and "dry-humid heat", meeting the usage requirements of different helicopters. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the guide tube of the automatic tilter of the present invention; where 1 is a cylindrical section, 3 is a conical section, and 31 is a convex ring; Figure 2 This is a perspective view of the guide tube of the automatic tilter of the present invention; where 32 is a bolt hole; Figure 3 This is a schematic diagram of the guide tube of the automatic tilter of the present invention; Figure 4 A schematic diagram of carbon fiber composite layup; Figure 5 This is a perspective view of the guide tube connection of the automatic tilter of the present invention; Figure 6 This is a schematic diagram of the guide tube connection of the automatic tilter of the present invention; Figure 7 This is a diagram showing the overall deformation effect of the guide tube of the automatic tilter of the present invention; Figure 8 This is a schematic diagram showing the maximum strain of the guide tube of the automatic tilter of the present invention; Figure 9 This is a schematic diagram of the maximum stress of the 0° ply in the guide tube of the automatic tilter of the present invention. Detailed Implementation

[0019] The present invention provides an automatic tilter guide tube, comprising a cylindrical section (1) and a conical section (3) connecting the cylindrical section (1), wherein the free end of the conical section (3) includes a convex ring (31) extending outward around the circumference, and wherein the automatic tilter guide tube is made of carbon fiber composite material. The carbon fiber composite material includes carbon fiber and organic modified materials; the organic modified materials include one or more of epoxy resin, bismaleimide and polyaryletherketone.

[0020] In this invention, unless otherwise specified, all raw materials are commercially available products well known to those skilled in the art.

[0021] In this invention, the carbon fiber composite material includes carbon fiber and organic modified materials; the organic modified materials include one or more of epoxy resin, bismaleimide, and polyaryletherketone (PAEK); the epoxy resin includes tetrafunctional glycidyl amines, specifically epoxy resin AG80; the toughened epoxy resin prepreg is 3900 series prepreg or TC275-1E prepreg, sourced from Toray Plastics; and the core-shell toughened epoxy resin EPX-125; the bismaleimide can specifically be HT-280.

[0022] In this invention, the carbon fiber has a single filament diameter of 7μm±0.2, a tensile strength ≥5GPa, and an elastic modulus ≥294GPa; the carbon fiber can specifically be T800 carbon fiber; the bundle specification is 12K-24K (1 bundle of T800 carbon fiber contains 12000 / 24000 7μm single filaments).

[0023] In this invention, the carbon fiber volume content in the carbon fiber composite material is 48-55%, and in specific embodiments it can be 50%, 53%, 54%, or 55%. The carbon fiber volume content is a core factor affecting the performance of the composite material; excessively high or low content will significantly degrade performance. In this invention, carbon fiber is the main load-bearing phase, while resin or organic materials play a role in bonding and load transfer; the two must work synergistically. For example, the optimal carbon fiber volume content for T800 carbon fiber epoxy composite laminates is 48%~55% (the industry-standard golden range). If the content is too low (<35%), the carbon fiber load-bearing ratio will be insufficient, and the tensile strength and elastic modulus will drop significantly, failing to leverage the high strength and high modulus advantages of T800. It is also prone to problems such as resin enrichment, shrinkage deformation, and increased porosity, resulting in the failure of both lightweighting and mechanical properties. If the content is too high (>60%), the resin will be insufficient to fully coat and bond the carbon fibers, causing a sharp drop in interlaminar shear strength and impact resistance. The laminate is prone to delamination and brittle fracture, fiber pull-out, and molding defects such as insufficient glue, dry filaments, and increased porosity, seriously wasting the performance of carbon fibers. Only by controlling it within the above-mentioned optimal range can the high strength and high modulus of the composite material, molding reliability, and service stability be balanced, and the material advantages of T800 carbon fiber be fully utilized.

[0024] In this invention, the density of the carbon fiber composite material is 1.5~1.65 g / cm³. 3 This invention uses the AG80 resin system as an example, with a specific strength of approximately 1222 MPa / (g / cm). 3 (Taking AG80 resin system as an example), it is the existing technology for 7075 aluminum alloy (211MPa / (g / cm)). 3 It is 5.8 times more effective than other products, which can lead to significant weight loss.

[0025] In this invention, the method for preparing the carbon fiber composite material includes the following steps: Carbon fibers are sandwiched between organic modified materials and hot-pressed impregnated to obtain the carbon fiber composite material; the carbon fibers also undergo a pre-treatment of fiber spreading before use; the present invention does not have special limitations on the conditions of hot-pressing impregnation; in a specific embodiment, carbon fibers are sandwiched between two layers of molten epoxy resin and hot-pressed impregnated.

[0026] In this invention, the convex ring (31) is provided with screw holes, and the distance between every two screw holes is 80~130mm.

[0027] In this invention, the size of the transition fillet (the curved part of the conical cylinder section) of the conical cylinder section (3) is ≥5mm; the distance between the screw hole and the outermost edge of the convex ring (31) is ≥2 times the diameter of the screw hole.

[0028] This invention also provides a method for preparing the carbon fiber composite automatic tilter guide tube described in the above technical solution, comprising the following steps: Carbon fiber composite material is laid layer by layer on the surface of the automatic tilter guide cylinder mold, and the carbon fiber composite material automatic tilter guide cylinder is obtained after molding.

[0029] In this invention, the mold can be a steel cylindrical mold with a surface roughness Ra≤0.8μm; before laying the carbon fiber composite material layer by layer onto the automatic tilter guide cylinder mold, a release agent is also applied, with a thickness of 5~10μm; this invention does not have any special limitation on the release agent, and any release agent well known to those skilled in the art can be used.

[0030] In this invention, the thickness of a single layer of the carbon fiber composite material is 0.1~0.2mm, and in specific embodiments it can be 0.125, 0.15 or 0.180mm; the number of layers is 30~50, and in specific embodiments it can be 32, 36, 40 or 48 layers.

[0031] In this invention, the layer-by-layer laying of carbon fiber composite material is mainly in the radial direction of the cylindrical section, specifically including laying in the 0°, 45°, -45°, and 90° directions; the lay-up ratio in the 0°, 45°, -45°, and 90° directions is 3:2:2:1.

[0032] In this invention, the layer-by-layer laying process includes laying the carbon fiber composite material onto the mold surface and compacting it to remove air bubbles. The compaction is performed using a silicone roller in a radial direction at a pressure of 0.2~0.5 MPa and a speed of 50~80 mm / s. This invention removes interlayer air bubbles through compaction. During the layer-by-layer laying process, an "intermediate inspection" is performed every 6~8 layers (as a group), specifically: using an ultrasonic flaw detector to detect interlayer air bubbles; the bubble diameter is ≤0.5 mm and the number is ≤1 bubble / m. 2 It is acceptable.

[0033] In this invention, the hot pressing temperature is 100~140℃, and in a specific embodiment it can be 120 or 130℃; the heating rate to the required hot pressing temperature is 2~10℃ / min, and in a specific embodiment it can be 5℃ / min; the pressure is 0.5~1.0MPa, and in a specific embodiment it can be 0.55 or 0.70MPa; the heat holding and pressure holding time is 1~3h.

[0034] In this invention, cooling is further included after the hot pressing process; the cooling rate is 1~3℃ / min, and in a specific embodiment it can be 2℃ / min. This invention controls the cooling rate to avoid cracking caused by excessive temperature difference.

[0035] In this invention, the stud hole is prepared after hot pressing; specifically, a diamond end mill is used to machine the stud hole; the machining speed is 1200~1500 r / min, and the feed rate is 30~50 mm / min. This invention controls the process within the above range to avoid splitting of the carbon fiber composite material.

[0036] To further illustrate the present invention, the carbon fiber composite automatic tilting guide tube and its preparation method provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0037] Examples 1-4 The carbon fiber composite material was prepared by hot-melt method according to the proportions described in Table 1. The specific steps are as follows: after continuous T800 carbon fiber is pretreated by spinning and tension control, it is sandwiched between two layers of molten resin film described in Table 1. Under temperature control, it is hot-pressed and impregnated to make the resin uniformly coat and penetrate the carbon fiber. After cooling and shaping, it is cut and vacuum-sealed for low-temperature storage to obtain T800 carbon fiber prepreg.

[0038] Table 1. Mix proportions and performance test data of carbon fiber composite materials obtained in Examples 1-4

[0039] The specific steps for preparing the carbon fiber composite material guide tube for the automatic tilter are as follows: Mold pretreatment: Select a steel cylindrical mold (surface roughness Ra≤0.8μm), apply a release agent with a thickness of 510μm, and let it air dry at room temperature for 30min; Prepreg cutting: Cut the above T800 carbon fiber prepreg according to the layup direction, with a cutting accuracy of ±0.5mm, to avoid fiber fuzzing; Laying operation: Lay the prepreg onto the mold surface in the order shown in Table 2. After each layer is laid, use a silicone roller (hardness 60 Shore A) to roll it radially at a pressure of 0.2 MPa and a speed of 50 mm / s, and remove interlayer air bubbles. Every 8 layers constitutes one group, and an "intermediate inspection" is performed. Use an ultrasonic flaw detector to check for interlayer air bubbles. The diameter of the air bubble should be ≤0.5 mm and the number should be ≤1 per m. 2 It is qualified; Table 2 Layup Scheme

[0040] Hot pressing: The mold with the ply laid layers is placed into a hot press. The hot pressing process parameters are as follows: Heating stage: from room temperature to 120℃, heating rate 2℃ / min; Holding stage: holding at 120℃ for 2 hours, while applying a pressure of 0.5MPa±0.05MPa; Cooling stage: cooling from 120℃ to room temperature, cooling rate 1℃ / min; After hot pressing, the mold is removed, and the screw hole is machined with a diamond end mill at a speed of 1500r / min and a feed rate of 50mm / min to obtain the carbon fiber composite automatic tilter guide cylinder.

[0041] Comparative Example 1 The automatic tilter guide tube was prepared according to the preparation method described in Examples 1-4, with the only difference being that the material was replaced with 7075 aluminum alloy.

[0042] Test Example 1 Table 3. Application performance test results of the carbon fiber composite material obtained in Example 1

[0043] As shown in Table 3, the carbon fiber composite material provided by this invention can be used for a long time (>10 years) in a weakly acidic environment (pH 5.6~6.5) with a performance decrease of <10%.

[0044] Test Example 2 Based on the Ansys ACP module, a simulation analysis was performed on the carbon fiber composite automatic tilter guide tube prepared in Example 1 of this invention. The simulation results are as follows: Figures 7-9 As shown. Through finite element analysis, the maximum overall deformation of the carbon fiber composite automatic tilter guide cylinder obtained in this invention is 0.17 mm, and the maximum stress in the 0° layup direction is 88.274 MPa. According to the Cai-Wu failure criterion, the failure factor is below 0.5, indicating that the structure is stable and reliable with no risk of failure.

[0045] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An automatic tilting guide cylinder, comprising a cylindrical section (1) and a conical section (3) connecting the cylindrical section (1), wherein the free end of the conical section (3) includes a convex ring (31) extending outward around the circumference, characterized in that, The guide tube of the automatic tilter is made of carbon fiber composite material; The carbon fiber composite material includes carbon fiber and organic modified materials; the organic modified materials include one or more of epoxy resin, bismaleimide and polyaryletherketone.

2. The automatic tilter guide tube according to claim 1, characterized in that, The carbon fiber composite material has a carbon fiber volume content of 48-55%.

3. The automatic tilter guide tube according to claim 1, characterized in that, The epoxy resin includes tetrafunctional glycidyl amines or toughened epoxy resin prepregs.

4. The automatic tilter guide tube according to claim 1, characterized in that, The carbon fiber has a single filament diameter of 7μm±0.2, a tensile strength ≥5GPa, and an elastic modulus ≥294GPa; The density of the carbon fiber composite material is 1.5~1.65 g / cm³. 3 .

5. The automatic tilter guide tube according to claim 1, characterized in that, The convex ring (31) is provided with screw holes, and the distance between every two screw holes is 80~130mm.

6. The automatic tilter guide tube according to claim 1, characterized in that, The transition radius of the conical cylinder section (3) is ≥5mm; the distance between the bolt hole and the outermost edge of the convex ring (31) is ≥2 times the diameter of the bolt hole.

7. The automatic tilter guide tube according to claim 1, characterized in that, The outer diameter of the cylindrical section (1) is 143±0.2mm, the inner diameter is 138±0.2mm, the height is 225±0.2mm, and the wall thickness is 5±0.2mm; The outer diameter of the free end of the conical cylinder section (3) is 143~190mm, and the inner diameter is 138~185mm; the height of the conical cylinder section (3) is 85±0.2mm, and the wall thickness is 5±0.2mm.

8. The method for preparing the automatic tilter guide tube according to any one of claims 1 to 7, characterized in that, Includes the following steps: Carbon fiber composite material is laid layer by layer on the surface of the automatic tilter guide cylinder mold, and the automatic tilter guide cylinder is obtained after molding.

9. The preparation method according to claim 8, characterized in that, The carbon fiber composite material has a single-layer thickness of 0.1~0.2mm and a number of layers of 30~50.

10. The preparation method according to claim 8, characterized in that, The molding process is hot pressing; the hot pressing temperature is 100~140℃, the pressure is 0.5~1.0MPa, and the heat and pressure holding time is 1~3h.

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