Carbon fiber composite transmission shaft and preparation method and application thereof

Abstract

The invention discloses a carbon fiber composite transmission shaft and a preparation method and application thereof, and belongs to the technical field of aerospace. The method comprises the steps that a mold core is preheated and coated with a release agent; at least two layers of flaky carbon fiber prepregs are overlapped and laid in a crossed mode, at least one layer of prepreg covers the joint of the adjacent layers of prepreg, sewing reinforcement is conducted in the laying layer overlapping area in the prepreg laying and rolling direction, a reinforced prepreg layer is formed and wound around a mold core, and the carbon fiber composite pipe is obtained through high-temperature curing and demolding; carrying out surface enhancement treatment on the connecting parts at the two ends of the pipe and the corresponding bonding parts of the splines; and the spline and the pipe are bonded and cured, the connecting position is riveted, and the carbon fiber composite transmission shaft is manufactured. Through layer-by-layer lap joint overlapping and sewing enhancement, the interaction force, the binding force, the interlayer shear strength and the torsion resistance between layers are increased, and the composite material is more stable when bearing torsion and complex shear force. The transmission system is suitable for the aerospace field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerospace, and particularly relates to a carbon fiber composite material transmission shaft and a preparation method and application thereof. BACKGROUND

[0002] Lightweight is the key to the development of materials and equipment in the fields of aerospace and automobiles. In the field of aerospace, the value of 1g weight reduction is equivalent to 1g of gold. The transmission shaft system is one of the heaviest key components in mechanical equipment, and its carrying capacity and dynamic mechanical properties directly affect the safety and stability of the entire mechanical equipment. The material of the transmission shaft for the high-lift system of the existing aerospace aircraft is aluminum alloy, and the density is 2.8g·cm -3 , and the demand for lightweight is urgent. Data shows that if the weight of the aircraft is reduced by 15%, the aircraft taxiing distance can be shortened by 15%, the flight range can be increased by 20%, and the effective load can be increased by 30%. As can be seen, lightweight design is of great significance in the field of aerospace. With the continuous development of new materials, the density of carbon fiber reinforced composite material is 1.5g·cm -3 , the tensile strength of carbon fiber is 2600Mpa, and the tensile modulus is 145Gpa, which is expected to replace traditional aluminum alloy and be applied to transmission shafts.

[0003] A Chinese patent application with publication number CN114523272A discloses a preparation method of an aluminum alloy transmission shaft. The transmission shaft includes a universal joint fork, a shaft tube, a spline sleeve, a spline shaft fork, etc. The shaft tube is connected with the universal joint fork and the spline sleeve by phase friction welding process; the spline shaft fork is a hollow structure; the shaft tube is an aluminum alloy seamless tube, and the ends of the shaft tube are upset before welding; the universal joint fork, the shaft tube, the spline sleeve, and the spline shaft fork are all subjected to solid solution and pre-aging treatment, and the universal joint fork, the shaft tube, and the spline sleeve are subjected to artificial aging treatment after welding. The manufactured aluminum alloy transmission shaft is reduced by more than 40% compared with the same level steel transmission shaft, and a special heat treatment process is adopted, which effectively makes up for the joint strength loss caused by the welding process, and at the same time, the shaft tube size can be further reduced under the premise of unchanged rated torque, realizing lightweight. The weight reduction effect has a greater advantage compared with the steel transmission shaft, but compared with the carbon fiber composite material, there is still a great weight reduction space. A Chinese patent application with publication number CN119189664A discloses a carbon fiber transmission shaft, which includes a shaft tube, the both ends of the shaft tube are fixedly provided with connecting pieces, the connecting pieces at the both ends of the shaft tube are fixedly connected with a sliding pair sleeve and a shaft fork respectively, the material of the shaft tube is carbon fiber composite material, and the materials of the connecting pieces, the sliding pair sleeve, and the shaft fork are all aluminum alloy. The problem of large weight of the traditional all-metal automotive transmission shaft affecting the driving maneuverability of the automobile is solved. The shaft tube of the invention is integrally formed by winding carbon fiber filaments and epoxy resin by wet winding, and is applied in the field of automobiles. The torsional resistance performance of the carbon fiber transmission shaft needs to be improved, and it is difficult to meet the application requirements of aerospace.

[0004] At present, the transmission shafts in the domestic aerospace field are all aluminum alloy, and a new transmission shaft with a carbon fiber composite material structure, a preparation method and application thereof need to be found out to further reduce the weight of the transmission shaft and meet the application requirements of high stiffness and anti-torsion transmission shaft. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the purpose of the present application is to provide a carbon fiber composite material transmission shaft, a preparation method and application thereof to solve the technical problem that the existing carbon fiber composite material transmission shaft cannot meet the requirements of high stiffness and lightweight transmission shaft in the aerospace field due to insufficient anti-torsion performance caused by weak interlayer bonding force.

[0006] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the present application: The present application discloses a preparation method of a carbon fiber composite material transmission shaft, comprising: preheating and applying a release agent to the mold core to obtain a pretreated mold core; crossing and overlapping at least two layers of sheet-shaped carbon fiber prepreg, wherein at least one layer of prepreg covers the joint of the adjacent layer of prepreg, and stitching reinforcement is performed in the overlapping area along the prepreg laying direction to form a reinforced prepreg laminate; winding the reinforced prepreg layer on the pretreated mold core, high-temperature curing and demolding to obtain a carbon fiber composite material pipe; performing surface reinforcement treatment on the connecting parts at both ends of the carbon fiber composite material pipe and the corresponding bonding parts of the spline, bonding and curing the spline and the carbon fiber composite material pipe, and then riveting the connecting position to obtain the carbon fiber composite material transmission shaft.

[0007] Preferably, the temperature for preheating the mold core is 120-150 DEG C, and the preheating time is 30-60 min. The mold core is an aluminum rod or a stainless steel rod.

[0008] Preferably, the crossing and overlapping laying adopts at least one of 2-5 layers of woven plain, woven twill, woven satin prepreg and unidirectional prepreg with different fiber orientations. The fiber orientation of the unidirectional prepreg is selected from at least one of 0 DEG, +45 DEG, -45 DEG and 90 DEG.

[0009] Preferably, the overlapping degree of the sheet-shaped prepreg between the adjacent layers of the crossing and overlapping laying is 30%-70%, the length of the sheet-shaped prepreg is 200-1500 mm, and the width is 100-1500 mm.

[0010] Preferably, the stitching line used for stitching reinforcement is a carbon fiber stitching line or a composite stitching line. The carbon fiber stitching line is a small-tow stitching line or a large-tow stitching line. The composite sewing thread is at least one of polyester and carbon fiber, aramid and carbon fiber, aramid and glass fiber, polyester and glass fiber, aramid and metal, and polyester and metal; The stitching direction is along the direction of laying the prepreg, the stitch spacing is 10-50mm, and the stitch is 3-10mm.

[0011] Preferably, the temperature of high-temperature curing is 120-180 DEG C, and the time of high-temperature curing is 1-3h.

[0012] Preferably, the lay-up structure of the carbon fiber composite pipe comprises the plain weave prepreg layer, the +45 DEG unidirectional prepreg layer and the -45 DEG unidirectional prepreg layer arranged in sequence.

[0013] Preferably, the spline is an aluminum alloy spline, and a thread groove or roughening structure for increasing the bonding area and mechanical engagement force is arranged at the bonding position of the carbon fiber composite pipe.

[0014] The application further discloses a carbon fiber composite drive shaft prepared by the preparation method of the carbon fiber composite drive shaft.

[0015] The application further discloses application of the carbon fiber composite drive shaft prepared by the preparation method of the carbon fiber composite drive shaft in an aircraft high-lift system transmission device.

[0016] Compared with the prior art, the application has the following beneficial effects: The application discloses a preparation method of a carbon fiber composite drive shaft, which eliminates the continuous joint between adjacent layers in the traditional pipe winding process through cross-over and overlapping lay-up, changes the load transmission path from single interlayer shear to multi-directional load transmission and distribution in the overlapping area, and significantly disperses stress concentration. The synchronous sewing introduces mechanical connection in the thickness direction, physically locks the fibers of each layer, greatly suppresses the interlayer delamination and relative sliding tendency, and improves the interlayer shear strength and torsional stiffness. The combined connection mode of gluing and riveting combines the advantages of uniform stress distribution of gluing and mechanical locking of riveting, ensures the connection reliability between the carbon fiber pipe and the metal spline under complex alternating torque, provides process guarantee for the application of the lightweight drive shaft in the high-reliability aviation field, and solves the weight reduction problem of the aluminum alloy drive shaft in the aviation field. The application adopts cross-over and overlapping sewing of the sheet carbon fiber prepreg for interlayer reinforcement, optimizes the mechanical properties of the carbon fiber drive shaft, innovates the carbon fiber pipe structure and forming method, designs the connection mode of the combined gluing and riveting, realizes reliable connection with the aluminum alloy splines at both ends, significantly reduces the weight of the drive shaft, improves the stiffness and torsional resistance, and can be applied to the aircraft high-lift system transmission device.

[0017] Further, the combination of multi-angle or different weaving forms of the layer group can be customized according to the torque, bending moment and other specific loads borne by the transmission shaft to realize optimal configuration of material performance. 0° provides axial stiffness, ±45° provides optimal resistance to torsion and shear. The cross-over and sewing process solves the problem that the traditional method is difficult to realize such complex and accurate interlaminar alternating placement, so that the design freedom and the final component performance are maximized.

[0018] Further, the degree of coincidence of the sheet-shaped prepreg between the adjacent layers of the cross-over and overlapping layers is 30%-70%; if the degree of coincidence is too low, the overlapping area is small, and the load transmission and stress dispersion effect is limited; if the degree of coincidence is too high, although the effect can be enhanced, the material usage and local thickness will be increased, which may introduce new process unevenness and weight increase. The degree of coincidence of 30%-70% can ensure the improvement of interlaminar enhancement effect while realizing lightweight and process controllability.

[0019] Further, the stitching line used for sewing reinforcement is a carbon fiber sewing line or a composite sewing line; the carbon fiber sewing line is a small-tow sewing line or a large-tow sewing line; the composite sewing line is at least one of polyester and carbon fiber, aramid and carbon fiber, aramid and glass fiber, polyester and glass fiber, aramid and metal, and polyester and metal; the use of carbon fiber or high-performance composite sewing line ensures the high strength, high modulus and good compatibility of the sewing line itself, avoiding becoming a performance short board. The stitching direction is along the prepreg laying direction, the stitch spacing is 10-50mm, and the stitch length is 3-10mm; the uniformity and effectiveness of the sewing reinforcement are ensured: enough dense sewing line can provide continuous Z-direction constraint to prevent local instability; reasonable spacing avoids excessive damage and stress concentration to the fibers caused by too dense sewing, and the best balance between reinforcement and damage is achieved.

[0020] Further, the temperature of high-temperature curing is 120-180℃, and the time of high-temperature curing is 1-3h; it is suitable for most aviation-grade epoxy resin prepreg systems to ensure that the resin is fully crosslinked to achieve the best mechanical properties and glass transition temperature, while avoiding excessive temperature or long time leading to resin degradation or excessive residual stress, ensuring the stability and consistency of the carbon fiber tube forming quality.

[0021] Further, the layer structure of the carbon fiber composite material tube comprises flat-woven prepreg layers, +45° unidirectional prepreg layers and -45° unidirectional prepreg layers arranged in sequence; the flat-woven layer is located at the outermost layer or the innermost layer, which can provide good surface quality and impact resistance; the sandwiched ±45° layer is the main load-bearing layer for resisting torsion, and this weaving layer + bidirectional ±45° structure provides excellent comprehensive torsional stiffness and fatigue resistance, which is a high-efficiency design for the typical working conditions of the transmission shaft.

[0022] Further, the spline is an aluminum alloy spline, and a thread groove or roughening structure is arranged at the bonding position of the aluminum alloy spline and the carbon fiber composite pipe to increase the bonding area and mechanical interlocking force; the aluminum alloy spline and the carbon fiber pipe can be further matched in lightweight. The thread groove or roughening treatment of the bonding surface greatly increases the effective bonding area and forms a micro mechanical interlocking structure, so that the adhesive can be more deeply filled and anchored to maximize the shear strength of the adhesive layer.

[0023] The carbon fiber composite drive shaft disclosed in the application has a carbon fiber pipe body which is not a simple unidirectional layup or ordinary stacking, but has a micro and macro structure with cross overlap and sewing. The structure gives the pipe excellent integrity, so that when the pipe bears torque, the shear stress can be effectively transmitted and redistributed between layers through the overlap area and the sewing line, rather than being concentrated on the weak interface, thereby showing a torsional resistance close to that of a monolithic component. The composite connection structure at both ends forms a double insurance mechanism of chemical bonding and mechanical interlocking, effectively solving the problem of failure of the connection of the composite material and the metal heterogeneous material under dynamic load, so that the drive shaft can still maintain the connection integrity under extreme working conditions, meeting the requirements of high safety and long service life of the aviation transmission system.

[0024] The application of the carbon fiber composite drive shaft disclosed in the application in the aircraft high-lift system transmission device is extremely sensitive to the weight and reliability of the transmission components. The application of the drive shaft reduces the weight by more than 30%, and the lightweight directly reduces the system inertia, improves the response speed, and brings overall benefits of fuel economy, range and payload. The high stiffness and high torsional resistance realized by the above-mentioned structural innovation can ensure that the drive shaft has small deformation and accurate transmission when the flight attitude changes and the aerodynamic load is complex and changeable, thereby ensuring the precision and safety of the operation of the high-lift system, and effectively solving the bottleneck that the existing carbon fiber drive shaft cannot enter the core field due to insufficient performance. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The figure is a schematic diagram of the prepreg layup and sewing of the carbon fiber composite drive shaft disclosed in the application.

[0026] 1, mold core; 2, sewing line; CF-1, first layer of prepreg layup; CF-2, second layer of prepreg layup; CF-3, third layer of prepreg layup. DETAILED DESCRIPTION

[0027] The technical solutions of the application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0028] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0029] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0030] In the present application, percentage (%) or part refers to the percentage by weight or weight parts of the composition, if not otherwise specified.

[0031] In the present application, each component or its preferred component involved can be combined to form new technical solutions, if not otherwise specified.

[0032] In the present application, unless otherwise specified, the numerical range "a~b" represents a shorthand notation for any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "6~22" represents that all the real numbers between "6~22" have been listed herein, and "6~22" is only a shorthand notation for these numerical combinations.

[0033] The lower limit and upper limit of the range disclosed in the present application can be one or more lower limits and one or more upper limits, respectively.

[0034] In the present application, the term "and / or" used herein means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0035] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or according to the sequence. Preferably, the reaction method herein is carried out sequentially.

[0036] Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied in the present application.

[0037] The present application provides a preparation method of a carbon fiber composite material transmission shaft, comprising: Step 1: Prepreg cutting. The carbon fiber prepreg is cut into a sheet-shaped prepreg of a certain size for standby; The carbon fiber prepreg is a unidirectional prepreg, a woven plain weave / twill weave / satin weave prepreg; The prepreg cutting method is to lay the prepreg on a cutting platform, manually cut or use a cloth cutting machine to cut the prepreg into a sheet-shaped prepreg of a fixed size for standby; The size can be cut into sheet-like prepregs of corresponding length according to the length requirements of the carbon fiber tube, with a length of 200-1500mm and a width of 100-1500mm.

[0038] Step 2: Apply release agent to mold core 1. First, place mold core 1 in an oven and preheat at 120 ℃ for more than 0.5 hours. After taking it out, immediately apply release agent and let it air dry naturally for later use.

[0039] Mold core 1 is a metal rod, including but not limited to aluminum rods, stainless steel rods, etc. The preheating conditions for mold core 1 are: temperature 120-150℃, preheating time 30-60min; Release agent, according to the mass ratio of release agent concentrate to diluent = 1:(5-20); The release agent stock solution is Dehui water-based solvent-based release agent, and the diluent is deionized water.

[0040] Step 3: The prepreg is laid in cross-overlap layers and reinforced with interlayer stitching.

[0041] The prepreg layup method is as follows: Align the long edges of the prepreg sheets to be rolled and lay them up in a straight line, naming this layer CF-1. Lay another portion of the prepreg sheets on top of the CF-1 layer, aligning their long edges, and lay them up in a straight line, ensuring the prepreg covers the seam between the two CF-1 layers; this layer is named CF-2. Then, lay another portion of the prepreg sheets on top of the CF-2 layer, aligning their long edges, and lay them up in a straight line, ensuring the prepreg covers the seam between the two CF-2 layers; this layer is named CF-3, and so on. Finally, sew the overlapping portions of each prepreg layer together with sewing thread for subsequent carbon fiber tube winding.

[0042] The CF-1 layer prepreg can be a 0°, ±45°, or 90° unidirectional prepreg and can be woven in any of the following patterns: plain weave, twill weave, or satin weave. The CF-2 layer prepreg can be a 0°, ±45°, or 90° unidirectional prepreg and can be woven in any of the following patterns: plain weave, twill weave, or satin weave. CF-3 layer prepreg can be 0°, ±45°, or 90° unidirectional prepreg and can be woven in any of the following patterns: plain weave, twill weave, or satin weave. And so on.

[0043] The layup design can adopt a 2-5 layer prepreg layup process. The types of prepregs can be arranged and combined arbitrarily according to actual needs. Taking a three-layer design as an example, three types of prepregs are selected: ±45° unidirectional prepreg and woven plain weave prepreg, as shown in Table 1.

[0044] Table 1 Prepreg Layup Design Scheme

[0045] The overlap of the prepreg layers is 30%-70% between adjacent layers; Sewing reinforcement involves sewing multiple layers of sheet prepreg together vertically using hand sewing or sewing equipment. The sewing direction is along the prepreg roll direction, the seam spacing is 10-50 mm, and the stitch length is 3-10 mm. The suture 2 is a carbon fiber sewing thread (small tow sewing thread, large tow sewing thread, etc.) or a composite carbon fiber sewing thread (at least one of polyester and carbon fiber, aramid and carbon fiber, aramid and glass fiber, polyester and glass fiber, aramid and metal, and polyester and metal). Step 4: Wrap the sewn prepreg onto the metal mold core 1 by hand or with a tube rolling machine.

[0046] Step 5: Wrap BOPP film or high-temperature resistant wrapping tape around the surface of the prepreg and place it in a curing fixture. Place it horizontally in an oven for high-temperature curing. After natural cooling, demold to obtain a carbon fiber composite tube.

[0047] The high-temperature curing temperature is 120-180℃, and the curing time is 1-3 hours.

[0048] Step 6: Reinforce the surfaces of the bonding areas at both ends of the carbon fiber tube and the spline, and clean them thoroughly; Bonding enhancement treatments include sanding and sandblasting, while cleaning operations include ultrasonic cleaning, rinsing, and blowing.

[0049] The spline is made of aluminum alloy, and the spline and carbon fiber tube adopt a threaded groove design.

[0050] Step 7: Apply high-strength epoxy structural adhesive (Loctite E-60HP epoxy adhesive) evenly to the bonding positions of the carbon fiber shaft and spline. Then install the spline to both ends of the carbon fiber shaft, ensuring that the bonding areas of the carbon fiber shaft and spline completely overlap. Place it horizontally on the curing rack. After curing, a carbon fiber composite drive shaft is obtained. Rivet the spline connection positions of the carbon fiber drive shaft with a rivet gun to finally obtain a carbon fiber composite drive shaft with a composite connection.

[0051] This invention discloses a carbon fiber composite drive shaft, its preparation method, and its applications. By using carbon fiber composite material to replace aluminum alloy drive shafts, the torsional resistance and weight reduction performance of carbon fiber drive shafts are significantly superior to aluminum drive shafts. Traditional carbon fiber tubes made from sheet prepregs suffer from insufficient interlayer bonding strength, making it difficult for the carbon fiber tubes to withstand large shear and torsional forces in the interlayer direction, thus limiting their applications. This invention increases the interaction force between layers and improves the interlayer bonding strength by overlapping and stitching reinforcement between layers. It also simultaneously addresses the difficulty of alternating winding of prepregs with different fiber orientations between adjacent layers during sheet prepreg winding, further improving interlayer shear strength and torsional resistance, making the carbon fiber tube more stable under torsional and complex shear forces. This device is suitable for transmission systems in the aerospace field and has broad application prospects and practical value.

[0052] The torsion angle and mass of the carbon fiber drive shaft prepared using this invention were compared with those of an aluminum alloy drive shaft that meets the same performance requirements. The results are shown in Table 2. The carbon fiber drive shaft is 1m long with an inner diameter of 40mm and an outer diameter of 50mm. The corresponding aluminum alloy drive shaft, meeting the performance requirements, has an outer diameter of 46mm, an inner diameter of 31mm, and a length of 1m. Both meet the design requirements in terms of torsion angle. The carbon fiber drive shaft demonstrates significant advantages in weight reduction, achieving a weight reduction of over 30%.

[0053] Table 2. Performance Comparison of Carbon Fiber Driveshaft and Aluminum Driveshaft

[0054] Figure 1 This diagram illustrates the prepreg layup and stitching of the carbon fiber composite drive shaft disclosed in this invention. As shown, the multi-layered, cross-overlapping structure utilizes three layers (CF-1, CF-2, CF-3) of sheet-like prepreg. The adjacent layers are not simply aligned and stacked, but rather cross-overlapped; that is, the upper prepreg layer (CF-2) covers and spans the seam between the lower prepreg layers (CF-1). This cross-overlapping layup method spatially staggers the seams of each prepreg layer, avoiding the formation of continuous weak interfaces along the tube's axial direction, thus effectively dispersing stress concentration and improving the overall integrity and continuity of the structure. Stitching line 2 runs through the multiple layers of prepreg. Stitching is performed vertically, along the Z-direction (layup thickness direction), after the cross-overlapping layup of each prepreg layer is completed, mechanically connecting the multiple layers into a single unit, demonstrating the core innovation of interlayer stitching reinforcement. The stitched reinforced prepreg composite is then rolled around the core 1 along the rolling direction indicated by the arrow, ultimately forming a tubular structure. The physical structure of cross-overlapping lay-up and Z-direction stitching reinforcement is a key design to solve the problems of weak interlayer bonding and insufficient shear and torsional resistance of traditional sheet prepreg rolls, effectively improving mechanical properties.

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0056] Example 1 This invention provides a method for preparing a carbon fiber drive shaft. The method involves using a layered carbon cloth prepreg to perform interlayer stitching, winding, and curing to obtain a carbon fiber tube. The splines at both ends are then connected using a composite connection method of adhesive bonding and riveting, ultimately resulting in a carbon fiber drive shaft. The specific steps are as follows: Step 1: Prepreg Cutting. Based on the requirements of a carbon fiber tube inner diameter of 40mm, an outer diameter of 50mm, and a length of 1000mm, cut the prepreg. Cut one sheet of unidirectional carbon fiber prepreg at a +45° angle, with a length of 1050mm and a width of 600mm, for later use. Cut two sheets of unidirectional carbon fiber prepreg at a -45° angle, with a length of 1050mm and a width of 600mm, for later use. Cut three pieces of plain weave prepreg, each with a length of 1050mm and a width of 600mm, for later use.

[0057] Step 2: Apply release agent to mold core 1. First, put the aluminum rod mold core 1 into an oven and preheat it at 120℃ for 0.5 hours. After taking it out, immediately apply release agent and let it air dry naturally for later use.

[0058] Step 3: Design a cross-overlay of prepreg and reinforce the interlayer stitching.

[0059] The prepreg layup design involves aligning the long edges of the prepreg sheets to be rolled and laying them out sequentially in a straight line, designated as the first prepreg layup CF-1. A portion of the prepreg sheets is then laid on top of the CF-1 layer, aligning their long edges, and laid out sequentially in a straight line. Each sheet of prepreg must cover the seam between two sheets of prepreg in the CF-1 layer, designated as the second prepreg layup CF-2. Another portion of the prepreg sheets is then laid on top of the CF-2 layer, aligning their long edges, and laid out sequentially in a straight line. Each sheet of prepreg must cover the seam between two sheets of prepreg in the CF-2 layer, designated as the third prepreg layup CF-3, and so on. The overlapping portions of each prepreg layer are then sewn together with stitching thread 2 for subsequent carbon fiber tube winding.

[0060] CF-1 layer prepreg is a plain weave prepreg; CF-2 layer prepreg is a +45° unidirectional prepreg; CF-3 layer prepreg is a -45° unidirectional prepreg; The layup design can adopt a 3-layer prepreg layup process.

[0061] The layup overlap is defined as a 70% overlap of sheet prepreg between adjacent layers; Sewing reinforcement involves sewing multiple layers of sheet prepreg together vertically using hand sewing or sewing equipment. The sewing direction is along the prepreg roll direction, the seam spacing is 20 mm, and the stitch length is 5 mm. The second suture is made of carbon fiber sewing thread.

[0062] Step 4: Wrap the sewn prepreg onto the metal core 1 by hand or with a tube rolling machine, controlling the outer diameter by the number of turns.

[0063] Step 5: Wrap BOPP film or high-temperature resistant wrapping tape around the surface of the prepreg and place it in the curing fixture. Tighten the fixing bolts of the curing fixture, place it horizontally in the oven, cure at high temperature, and after natural cooling, demold to obtain the finished carbon fiber tube.

[0064] The high-temperature curing temperature is 150℃, and the curing time is 2 hours. Step 6: Perform bonding reinforcement treatment on the surfaces of the bonding positions at both ends of the carbon fiber tube and the spline. Sand the carbon fiber surface with sandpaper and clean it in an ultrasonic cleaner. Step 7: Apply high-strength epoxy resin structural adhesive evenly to the bonding positions of the carbon fiber shaft and spline, then install the spline to both ends of the carbon fiber shaft, ensuring that the bonding areas of the carbon fiber shaft and spline completely overlap. Place it horizontally on the curing rack, and after curing, obtain the carbon fiber drive shaft. Use a rivet gun to rivet the spline connection positions of the carbon fiber drive shaft to finally obtain a carbon fiber composite material drive shaft with a composite connection.

[0065] Example 2 This invention provides a method for preparing a carbon fiber drive shaft. The method involves using a layered carbon cloth prepreg to perform interlayer stitching, winding, and curing to obtain a carbon fiber tube. The splines at both ends are then connected using a composite connection method of adhesive bonding and riveting, ultimately resulting in a carbon fiber drive shaft. The specific steps are as follows: Step 1: Prepreg Cutting. Based on the requirements of 30mm inner diameter, 40mm outer diameter, and 200mm length of carbon fiber tube, cut the prepreg. Cut the unidirectional carbon fiber prepreg into 4 sheets, each 300mm wide and 250mm long, at a 90° angle, for later use. Cut the twill prepreg into 5 pieces, each 300mm wide and 250mm long, for later use.

[0066] Step 2: Apply release agent to mold core 1. First, put the stainless steel rod mold core 1 into an oven and preheat it at 120℃ for 30 minutes. After taking it out, immediately apply the release agent (prepared according to the mass ratio of release agent concentrate: diluent = 1:5) and let it air dry for later use.

[0067] Step 3: Design a cross-overlay of prepreg and reinforce the interlayer stitching.

[0068] The prepreg layup design involves aligning the long edges of a portion of the prepreg sheets to be rolled and laying them out sequentially in a straight line, designated as the first prepreg layup CF-1. A portion of the prepreg sheets is then laid on top of the CF-1 layer, aligning their long edges and laid out sequentially in a straight line. Each sheet of prepreg needs to cover the seam between two sheets of prepreg in the CF-1 layer; this is designated as the second prepreg layup CF-2. The overlapping portions of each prepreg layer are then sewn together with stitching thread 2 for subsequent carbon fiber tube winding.

[0069] CF-1 layer prepreg is a 90° unidirectional prepreg; CF-2 layer prepreg is a twill prepreg; The layup design uses a two-layer prepreg layup process.

[0070] The layup overlap is defined as a 50% overlap of sheet prepreg between adjacent layers; Sewing reinforcement involves using sewing equipment to sew multiple layers of sheet prepreg together vertically, with the sewing direction along the prepreg roll direction, the seam spacing being 10mm, and the stitch length being 3mm. The suture 2 is a small bundle of carbon fiber sewing thread.

[0071] Step 4: Manually wrap the sewn prepreg onto the metal core 1, controlling the outer diameter by the number of turns.

[0072] Step 5: Wrap the surface of the prepreg with high-temperature resistant wrapping tape, place it in the curing fixture, tighten the fixing bolts of the curing fixture, place it horizontally in the oven, cure at high temperature, and after natural cooling, demold to obtain the finished carbon fiber tube.

[0073] The high-temperature curing temperature is 120℃, and the curing time is 1 hour. Step 6: Perform bonding reinforcement treatment on the surfaces of the bonding positions at both ends of the carbon fiber tube and the spline. The carbon fiber surface is sandblasted and then cleaned by rinsing. Step 7: Apply high-strength epoxy resin structural adhesive evenly to the bonding positions of the carbon fiber shaft and spline, then install the spline to both ends of the carbon fiber shaft, ensuring that the bonding areas of the carbon fiber shaft and spline completely overlap. Place it horizontally on the curing rack, and after curing, obtain the carbon fiber drive shaft. Use a rivet gun to rivet the spline connection positions of the carbon fiber drive shaft to finally obtain a carbon fiber composite material drive shaft with a composite connection.

[0074] Example 3 This invention provides a method for preparing a carbon fiber drive shaft. The method involves using a layered carbon cloth prepreg to perform interlayer stitching, winding, and curing to obtain a carbon fiber tube. The splines at both ends are then connected using a composite connection method of adhesive bonding and riveting, ultimately resulting in a carbon fiber drive shaft. The specific steps are as follows: Step 1: Prepreg Cutting. Based on the requirements of a carbon fiber tube inner diameter of 10mm, an outer diameter of 30mm, and a length of 600mm, cut the prepreg. Cut 11 sheets of unidirectional carbon fiber prepreg, each 360mm wide and 650mm long, at a +45° angle, for later use. Cut 5 sheets of unidirectional carbon fiber prepreg, each 360mm wide and 650mm long, at a -45° angle, for later use. Cut 9 pieces of satin-weave prepreg, each 360mm wide and 650mm long, for later use.

[0075] Step 2: Apply release agent to mold core 1. First, put the aluminum rod mold core 1 into an oven and preheat it at 150℃ for 60 minutes. After taking it out, immediately apply the release agent (prepared according to the mass ratio of release agent concentrate: diluent = 1:20) and let it air dry for later use.

[0076] Step 3: Design a cross-overlay of prepreg and reinforce the interlayer stitching.

[0077] The prepreg layup design is as follows: A portion of the prepreg sheets to be rolled is aligned along its long sides and laid out sequentially in a straight line, named the first prepreg layup CF-1. A portion of the prepreg sheets is then laid on top of the CF-1 layer, aligned along its long sides, and laid out sequentially in a straight line. Each sheet of prepreg must cover the seam between two sheets of prepreg in the CF-1 layer, named the second prepreg layup CF-2. Another portion of the prepreg sheets is then laid on top of the CF-2 layer, aligned along its long sides, and laid out sequentially in a straight line. Each sheet of prepreg must cover the seam between two sheets of prepreg in the CF-2 layer, named the third prepreg layup CF-3. The fourth and fifth prepreg layups, CF-4 and CF-5, are then laid out, each layer covering the seam between the two sheets of prepreg below it. Then, the overlapping parts of each layer of prepreg are sewn together with stitching thread 2 for subsequent winding of carbon fiber tubes.

[0078] CF-1 layer prepreg is a +45° unidirectional prepreg; CF-2 layer prepreg is a -45° unidirectional prepreg; CF-3 layer prepreg is a satin prepreg; CF-4 layer prepreg is a +45° unidirectional prepreg; CF-5 layer prepreg is a -45° unidirectional prepreg; The layup design uses a 5-layer prepreg layup process.

[0079] The layup overlap is defined as a 40% overlap of sheet prepreg between adjacent layers; Sewing reinforcement involves using sewing equipment to sew multiple layers of sheet prepreg together vertically, with the sewing direction along the prepreg roll direction, the seam spacing being 50mm, and the stitch length being 10mm. Seam 2 is a polyester composite sewing thread.

[0080] Step 4: Use a tube winding machine to wind the sewn prepreg onto the metal mold core 1, and control the outer diameter by the number of turns.

[0081] Step 5: Wrap BOPP film around the surface of the prepreg and place it in the curing fixture. Tighten the fixing bolts of the curing fixture, place it horizontally in the oven, cure at high temperature, and after natural cooling, demold to obtain the finished carbon fiber tube.

[0082] The high-temperature curing temperature is 180℃, and the curing time is 3 hours.

[0083] Step 6: Perform bonding reinforcement treatment on the surfaces of the two ends of the carbon fiber tube and the spline bonding positions. Sand the carbon fiber surface with sandpaper and clean it by blowing.

[0084] Step 7: Apply high-strength epoxy resin structural adhesive evenly to the bonding positions of the carbon fiber shaft and spline, then install the spline to both ends of the carbon fiber shaft, ensuring that the bonding areas of the carbon fiber shaft and spline completely overlap. Place it horizontally on the curing rack, and after curing, obtain the carbon fiber drive shaft. Use a rivet gun to rivet the spline connection positions of the carbon fiber drive shaft to finally obtain a carbon fiber composite material drive shaft with a composite connection.

[0085] Example 4 This invention provides a method for preparing a carbon fiber drive shaft. The method involves using a layered carbon cloth prepreg to perform interlayer stitching, winding, and curing to obtain a carbon fiber tube. The splines at both ends are then connected using a composite connection method of adhesive bonding and riveting, ultimately resulting in a carbon fiber drive shaft. The specific steps are as follows: Step 1: Prepreg Cutting. Based on the requirements of a carbon fiber tube inner diameter of 20mm, an outer diameter of 40mm, and a length of 1200mm, cut the prepreg. Cut one sheet of satin prepreg with a width of 1500mm and a length of 1250mm for later use. Cut one sheet of unidirectional carbon fiber prepreg with a width of 1300mm and a length of 1250mm at a +45° angle for later use. Cut one sheet of unidirectional carbon fiber prepreg with a width of 1100mm and a length of 1250mm at a -45° angle for later use. Cut one sheet of unidirectional carbon fiber prepreg with a width of 900mm and a length of 1250mm at a 90° angle for later use.

[0086] Step 2: Apply release agent to mold core 1. First, put the stainless steel rod mold core 1 into an oven and preheat it at 135℃ for 45 minutes. After taking it out, immediately apply the release agent (prepared according to the mass ratio of release agent concentrate: diluent = 1:12) and let it air dry for later use.

[0087] Step 3: Design a cross-overlay of prepreg and reinforce the interlayer stitching.

[0088] The prepreg layup design is as follows: A portion of the prepreg sheets to be rolled is aligned along its long sides and laid out sequentially in a straight line, named the first prepreg layup CF-1. A portion of the prepreg sheets is then laid on top of the CF-1 layer, aligned along its long sides, and laid out sequentially in a straight line. Each sheet of prepreg needs to cover the seam between two sheets of CF-1, named the second prepreg layup CF-2. Another portion of the prepreg sheets is then laid on top of the CF-2 layer, aligned along its long sides, and laid out sequentially in a straight line. Each sheet of prepreg needs to cover the seam between two sheets of CF-2, named the third prepreg layup CF-3. The fourth prepreg layup, CF-4, is then laid out, covering the seam between the two sheets of CF-3. The overlapping portions of each prepreg layer are then sewn together with stitching thread 2 for subsequent carbon fiber tube winding.

[0089] CF-1 layer prepreg is a satin prepreg; CF-2 layer prepreg is a +45° unidirectional prepreg; CF-3 layer prepreg is a -45° unidirectional prepreg; CF-4 layer prepreg is a 90° unidirectional prepreg; The layup design uses a 4-layer prepreg layup process.

[0090] The layup overlap is defined as a 30% overlap of sheet prepreg between adjacent layers; Sewing reinforcement involves using sewing equipment to sew multiple layers of sheet prepreg together vertically, with the sewing direction along the prepreg roll direction, the seam spacing being 30mm, and the stitch length being 7mm. The suture thread 2 is an aramid composite sewing thread.

[0091] Step 4: Use a tube winding machine to wind the sewn prepreg onto the metal mold core 1, and control the outer diameter by the number of turns.

[0092] Step 5: Wrap the surface of the prepreg with high-temperature resistant wrapping tape, place it in the curing fixture, tighten the fixing bolts of the curing fixture, place it horizontally in the oven, cure at high temperature, and after natural cooling, demold to obtain the finished carbon fiber tube.

[0093] The high-temperature curing temperature is 150℃, and the curing time is 2 hours. Step 6: Perform bonding reinforcement treatment on the surfaces of the bonding positions at both ends of the carbon fiber tube and the spline. The carbon fiber surface is sandblasted and cleaned by a combination of ultrasonic cleaning and rinsing. Step 7: Apply high-strength epoxy resin structural adhesive evenly to the bonding positions of the carbon fiber shaft and spline, then install the spline to both ends of the carbon fiber shaft, ensuring that the bonding areas of the carbon fiber shaft and spline completely overlap. Place it horizontally on the curing rack, and after curing, obtain the carbon fiber drive shaft. Use a rivet gun to rivet the spline connection positions of the carbon fiber drive shaft to finally obtain a carbon fiber composite material drive shaft with a composite connection.

[0094] In summary, this invention addresses the urgent need for high stiffness and lightweight drive shafts in the aerospace field by providing a carbon fiber composite drive shaft, its preparation method, and its applications. First, multiple layers of sheet-like carbon fiber prepregs with different fiber orientations are cross-laid, with the upper prepreg covering the seams of the lower layers, achieving physical misalignment of the seams and optimized load path dispersion. Next, vertical stitching reinforcement is performed along the layup direction in the overlapping area, using carbon fiber stitching threads to form mechanical connections in the thickness direction, physically locking the layers together. This reinforced composite is then wound onto a mold core 1 and cured into a tube. Finally, the two ends of the carbon fiber tube are assembled with aluminum alloy splines using a composite connection method combining adhesive bonding and riveting, combined with interface roughening treatment, ensuring extreme reliability of the heterogeneous material connection. The cross-layup and stitching technology overcomes the common problem of weak interlayer bonding in traditional prepreg rolled tubes, significantly improving interlayer shear strength and anti-delamination ability, enabling the composite material to behave like a whole when subjected to torsion and complex shear forces, thus achieving high torsional stiffness close to the design limit. Leveraging the inherent low density of carbon fiber and combined with optimized layup design, the final component achieves a weight reduction of over 30% compared to aluminum alloy driveshafts with equivalent performance, directly contributing to the aircraft's fuel efficiency, range, and payload. The adhesive-riveted composite connection design significantly ensures the driveshaft's connection reliability and long service life under harsh dynamic load environments such as high-lift aircraft systems. This successfully transforms the lightweight potential of carbon fiber composites into high-performance, highly reliable driveshaft products that meet the cutting-edge needs of aerospace.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of manufacturing a carbon fiber composite drive shaft, characterized by, The application relates to a preparation method of a carbon fiber composite material transmission shaft. The method comprises the following steps: preheating and applying release agent to a mold core (1) to obtain a pretreated mold core; At least two sheet-shaped carbon fiber prepregs are cross-laid and overlapped, at least one of the prepregs covers the joint of the adjacent prepreg, and sewing reinforcement is carried out along the prepreg laying direction in the overlapping area of the prepregs to form a reinforced prepreg laminate; The reinforced prepreg laminate is wound on the pretreated mold core, high-temperature curing and mold stripping are carried out, and a carbon fiber composite material pipe is obtained; The connecting position of the carbon fiber composite material pipe and the corresponding bonding position of the spline are subjected to surface reinforcement treatment, the spline is bonded to the carbon fiber composite material pipe, curing is carried out, riveting is carried out on the connecting position, and the carbon fiber composite material transmission shaft is prepared.

2. The method of manufacturing a carbon fiber composite drive shaft according to claim 1, wherein, The preheating temperature of the mold core (1) is 120-150 DEG C, and the preheating time is 30-60 min; The mold core (1) is an aluminum rod or a stainless steel rod.

3. The method for preparing the carbon fiber composite drive shaft according to claim 1, characterized in that, The cross-laid and overlaid prepregs are at least one of 2-5 layers of woven plain, woven twill, woven satin prepregs and unidirectional prepregs with different fiber orientations. The fiber orientation of the unidirectional prepreg is at least one of 0 DEG, +45 DEG, -45 DEG and 90 DEG.

4. The method of manufacturing a carbon fiber composite drive shaft according to claim 1, wherein The overlapping degree of the sheet-shaped prepregs between the adjacent layers of the cross-laid and overlaid prepregs is 30%-70%, the length of the sheet-shaped prepregs is 200-1500 mm, and the width of the sheet-shaped prepregs is 100-1500 mm.

5. The method of manufacturing a carbon fiber composite drive shaft according to claim 1, wherein The sewing reinforcement adopts a sewing thread (2) which is a carbon fiber sewing thread or a composite sewing thread. The carbon fiber sewing thread is a small-tow sewing thread or a large-tow sewing thread. The composite sewing thread is at least one of polyester and carbon fiber, aramid and carbon fiber, aramid and glass fiber, polyester and glass fiber, aramid and metal, and polyester and metal. The sewing direction is along the prepreg laying direction, the stitch spacing is 10-50 mm, and the stitch length is 3-10 mm.

6. The method of manufacturing a carbon fiber composite drive shaft according to claim 1, wherein The high-temperature curing temperature is 120-180 DEG C, and the high-temperature curing time is 1-3 h.

7. The method of manufacturing a carbon fiber composite drive shaft according to claim 1, wherein The laying structure of the carbon fiber composite material pipe comprises, in sequence, a plain woven prepreg layer, a +45 DEG unidirectional prepreg layer and a -45 DEG unidirectional prepreg layer.

8. The method of manufacturing a carbon fiber composite drive shaft of claim 1, wherein, The spline is an aluminum alloy spline, and the bonding position of the spline and the carbon fiber composite material pipe is provided with a thread groove or a roughening structure for increasing the bonding area and mechanical engagement force.

9. A carbon fiber composite drive shaft, characterized by, The carbon fiber composite material transmission shaft is prepared by the preparation method of any one of claims 1-8.

10. The application of the carbon fiber composite material transmission shaft prepared by the preparation method of any one of claims 1-8 in an airplane high-lift system transmission device.

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