Forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes

Abstract

The present invention provides a method for forming, composite, and integrated carbon fiber reinforced aluminum alloy sandwich tubes. The method comprises: electroplating carbon fibers with nickel to obtain carbon fibers having a surface nickel layer; wrapping and stacking small-diameter aluminum alloy tubes with nickel-plated carbon fiber tubes and placing them in a circular array between medium- and large-diameter aluminum alloy tubes to obtain an uncompounded carbon fiber reinforced nickel-plated aluminum alloy sandwich structure laminated tube; and employing solid particle medium bulging technology to achieve diffusion bonding between the nickel layer and the aluminum alloy tubes and the overall formation of the sandwich structure and tubes. The present invention utilizes a diffusion metallurgical composite reaction between the nickel layer and the aluminum alloy to improve defects such as uneven resin distribution or bubbles during the bonding process. Furthermore, the method introduces internal small-diameter tube reinforcement to enhance the overall stiffness and load-bearing capacity of the carbon fiber aluminum alloy tube. Furthermore, the method utilizes the non-uniform distribution pressure transmission characteristics of the solid particle medium and an ultrasonically assisted energy field to achieve the forming, composite, and integrated processing of the carbon fiber reinforced aluminum alloy sandwich tubes.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber reinforced aluminum alloy pipes, and in particular to a forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes. Background Art

[0002] Aluminum alloys offer high strength, hardness, excellent corrosion resistance, formability, and weldability, making them a preferred material for lightweight applications. Their diverse range of properties and performance have led to their widespread application in transportation, aerospace, and electrical and electronic fields. Carbon fiber-reinforced aluminum alloys, which emerged on this basis, organically combine the excellent properties of composite materials and metals, leveraging their respective strengths to achieve lightweight, high strength, high modulus, and high wear resistance. However, research on these materials is still in its early stages, and the application market is relatively small, but they are expected to expand in the future.

[0003] Currently, the internal high-pressure forming technology for metal pipes can be divided into soft mold forming and rigid mold forming. The rigid mold forming technology is to use a segmented rigid punch to pressurize the pipe, and this process is widely used in actual production. The soft mold forming technology mainly changes the rigid punch into an elastic material, that is, using liquid, gas, etc. as the force transmission medium. This technology mainly includes elastomer soft mold forming technology, hydraulic forming technology and gas pressure expansion process. The solid particle forming process is one of the soft mold forming processes. It can be used as a new process for pipe forming. It overcomes the shortcomings of traditional processes and has its own unique technical advantages. Its application in the forming of carbon fiber reinforced aluminum alloy pipes can well meet the needs of pipe forming and compounding.

[0004] In some common tubular frame structures, researchers typically use external reinforcement ribs to improve the load-bearing capacity and seismic resistance of components in order to enhance their overall mechanical properties, which greatly limits the components' use environments. This invention uses a nickel-aluminum reaction to replace traditional resin bonding, combined with internal reinforcement structures and solid particle medium forming technology, to integrate the preparation and forming processes of carbon fiber-reinforced aluminum alloy sandwich tubes. The resulting nickel-plated carbon fiber and aluminum alloy tube composite is uniform, resulting in higher shape accuracy and better mechanical properties for carbon fiber-reinforced aluminum alloy tube components. Summary of the Invention

[0005] The purpose of the present invention is to provide a forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich tubes. By nickel plating the carbon fiber surface, the nickel layer and the aluminum alloy are combined to form a composite reaction instead of the traditional method of bonding carbon fiber and metal through resin. On this basis, the overall stiffness and load-bearing capacity of the carbon fiber aluminum alloy tube are improved by introducing internal small-diameter tube reinforcement.

[0006] In the present invention, a forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes involves a small-diameter aluminum alloy pipe, carbon fiber, a medium-diameter aluminum alloy pipe, a large-diameter aluminum alloy pipe, a feeding device, an axial compression pressure head, a first forming die, an ultrasonic device, a spring group A, a spring group B, a press, a second forming die, a pad, a pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminated pipe, a stud, solid particles, bolts and a composite carbon fiber reinforced nickel-plated aluminum alloy laminated pipe.

[0007] The present invention provides a forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes, and the specific implementation steps are as follows:

[0008] S1, preparing carbon fiber with nickel layer deposited on the surface;

[0009] S2. Prepare three aluminum alloy tubes with different inner diameters. Wrap and stack the small-pore aluminum alloy tube with carbon fibers along the radial direction of the aluminum alloy tube and place them in a circular array between the medium-pore aluminum alloy tube and the large-pore aluminum alloy tube to obtain an uncompounded carbon fiber-reinforced nickel-plated aluminum alloy laminate tube.

[0010] S3. Assemble the solid particle bulging mold and the ultrasonic device to obtain a forming mold for compounding:

[0011] S31, vertically placing the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube in a forming mold, so that the bottom of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube overlaps with the backing plate at the bottom of the mold, forming a barrel-shaped semi-enclosed space;

[0012] S32, adding solid particles to the innermost layer of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, so that the solid particles fill the entire cavity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube;

[0013] S33, using an axial punch to press into the carbon fiber reinforced nickel-plated aluminum alloy laminate tube from above, forming a closed space inside the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, and then assembling an ultrasonic vibration device on the axial punch to obtain a forming mold for composite;

[0014] S4. According to the temperature required for the composite reaction between the nickel layer and the aluminum alloy (Ni / Al→NiAl3→Ni2Al3), the forming mold used for composite is heated to 200-300°C and the temperature is kept constant;

[0015] The free deformation zone of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube in S3 is intercepted. In the unit at the maximum deformation point, the tangential stress is the first principal stress, and the radial force and axial force are close to zero. Using the third theoretical strength, when the first principal stress is equal to the yield stress, the tube begins to deform and enters the plastic stage from the elastic stage. The internal pressure at this time is:

[0016]

[0017] Where p s is the internal pressure value when the carbon fiber reinforced nickel-plated aluminum alloy laminated tube enters the plastic stage from the elastic stage, σ s is the yield stress, A and B are functions of β, μ is the Poisson's ratio of the material, δ is the thickness of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, a is the outer radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, and l is the total length of the free deformation zone;

[0018] At any moment during deformation of the deformation zone, the typical unit C at the center of the convex ring is analyzed and obtained. The isotropic stress and forming internal pressure at the typical unit C are:

[0019]

[0020]

[0021]

[0022] Where, σ θ is the hoop stress; σ t It is the tangential direction of the meridian plane; is the equivalent stress; P is the internal pressure during the forming of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; δ is the thickness of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; R0 is the inner radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; R1 is the outer radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube after forming; R2 is the inner radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube after forming; γ is the central angle of the free deformation zone;

[0023] Applying a pressure of 0-10 MPa to the carbon fiber reinforced nickel-plated aluminum alloy tube, maintaining the pressure for 0-1 minute, and performing ultrasonic vibration to obtain a pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube;

[0024] S5. Based on S4, after heating the temperature of the solid particles in the forming mold for composite to 400-500° C., maintaining the temperature unchanged, continue to use the axial compression head to apply the same ultrasonic vibration and extrude the solid particles to form the pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminated tube, the forming pressure is 20-30 MPa, and the forming time is 2-3 minutes, so that the carbon fiber reinforced nickel-plated aluminum alloy laminated tube is completely fitted with the rigid concave die in the forming mold, and a carbon fiber reinforced nickel-plated aluminum alloy laminated tube with a preset shape is obtained;

[0025] S6. After the carbon fiber reinforced nickel-plated aluminum alloy laminate tube is formed, the holding pressure is 20-30 MPa and the holding time is 40-50 minutes; then the pressure is reduced to 0 MPa to obtain the composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0026] Preferably, the forming raw materials used in the forming and composite integration method of the carbon fiber aluminum alloy tube include a small-diameter aluminum alloy tube, carbon fiber, a medium-diameter aluminum alloy tube, and a large-diameter aluminum alloy tube. The raw materials are placed accordingly and semi-compounded to obtain a pre-compounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube, which is then formed again to obtain a composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0027] The forming device includes a feeding device, an axial compression ram, a first forming mold, an ultrasonic device, a spring group A, a spring group B, a press, a second forming mold, a pad, studs, solid particles and bolts; after the axial compression ram is installed in the press, it is fixed to the feeding device with the spring group A and bolts, and then the pad, the second forming mold and the first forming mold are placed in sequence according to the corresponding positions, and the first forming mold and the feeding device are fixed with the spring group B and studs. After the raw material pipe is loaded, the solid particles are poured in and the ultrasonic device is installed to achieve pre-composite and composite forming.

[0028] Preferably, the specific implementation steps of step S1 include:

[0029] S11, placing the carbon fiber in a box-type resistance furnace at a temperature of 400°C and heating for 30 minutes to remove the glue;

[0030] S12, washing the debonded carbon fiber with water, placing it in nitric acid for roughening, and then washing it with water again after roughening;

[0031] S13, electroplating the carbon fiber obtained in S12 to obtain nickel-plated carbon fiber.

[0032] Preferably, the specific implementation steps of step S2 include:

[0033] S21, laying the nickel-plated carbon fiber, and determining the wrapping method of the nickel-plated carbon fiber according to the angle between the 0° carbon fiber tow and the axis of the aluminum alloy tube when the laid nickel-plated carbon fiber cloth is rolled into a tube;

[0034] S22, cutting out nickel-plated carbon fibers with an area equal to that of the sidewall of the small-diameter aluminum alloy tube, and wrapping the nickel-plated carbon fibers around the outside of the small-diameter aluminum alloy tube;

[0035] S23. Place the small-pore aluminum alloy tube wrapped with nickel-plated carbon fiber in a circumferential array between the medium-pore aluminum alloy tube and the large-pore aluminum alloy tube to obtain an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0036] Preferably, in step S13, the electroplating solution is a mixture of 250 g / L NiSO4·6H2O, 10 g / L NaCl, 30 g / L H3BO3 and 80 g / L Na2SO4, stirred evenly, and the pH value is controlled at 5; the electroplating current density is 0.2-0.4 A / dm 2 , the electroplating time is 2-8min.

[0037] Preferably, the feeding device, axial compression head, ultrasonic device, first forming mold, spring group A and spring group B constitute a spring axial feeding and feeding structure. By adjusting the stiffness ratio of spring group A and spring group B, the internal pressure of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube from mold closing to uncompounded and the internal pressure of the automatically fed solid particles during pre-compounding and composite forming can meet the requirements.

[0038] Preferably, in step S2, the nickel-plated carbon fiber is laid in a 0°-90°-0° manner, and the nickel-plated carbon fiber wraps the inner tube in a 0° manner, with the direction of the carbon fiber tow being parallel to the axis of the aluminum alloy tube.

[0039] Preferably, in step S3, the ultrasonic vibration device and the axial punch are assembled by means of interference fit.

[0040] Preferably, the diameter of the small-diameter aluminum alloy tube in step S2 is 3-5 mm, the diameter of the medium-diameter aluminum alloy tube is 20-30 mm, and the diameter of the large-diameter aluminum alloy tube is 26-40 mm.

[0041] Preferably, in step S3, the diameter of the solid particles is 0.3 to 0.8 mm.

[0042] Preferably, before preparing the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube in step S2, the aluminum alloy tube needs to be subjected to electrolytic corrosion treatment and deoxidation and drying treatment to obtain a pretreated aluminum alloy layer tube.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] 1. The present invention manufactures an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube by nickel-plating carbon fiber, and performs an integrated semi-curing and curing forming process to obtain the required metal layer tube structure, thereby simplifying the process flow of the entire manufacturing process.

[0045] 2. The present invention applies ultrasonic vibration synchronously during a series of manufacturing processes, effectively reducing local stress concentration and local deformation, making the wall thickness of the pipe uniform and significantly improving the quality of the formed parts.

[0046] 3. This invention utilizes solid particle bulging technology, resulting in a simple mold structure and addressing environmental pollution issues. Furthermore, the non-uniform distribution and pressure-transfer characteristics of the solid particle medium maximize the mechanical properties of the material. The solid particle medium provides relatively uniform normal stress, resulting in a uniform and excellent composite effect between nickel-plated carbon fiber and aluminum alloy tubing, and high-precision carbon fiber-reinforced aluminum alloy tubular components. Solid particle medium forming is a soft mold forming method, resulting in excellent part forming results.

[0047] 4. The middle carbon fiber layer of the composite pipe in the present invention can also be laid differently according to production needs to enhance practical performance.

[0048] 5. The present invention utilizes a composite reaction between a nickel layer and an aluminum alloy to replace the traditional method of bonding carbon fiber and metal through resin, thereby avoiding defects such as blistering or uneven resin distribution that are prone to occur during the resin curing and bonding process.

[0049] 6. Thin-walled tubular structures, as excellent buffer and energy-absorbing components, have been widely used by researchers in various fields. Reinforced structures are a commonly used reinforcement method in fields such as aerospace, transportation bridges, and civil engineering. Therefore, the present invention introduces internal small-diameter tubular reinforcement to improve the overall stiffness and load-bearing capacity of the carbon fiber aluminum alloy tubing. The porous sandwich structure created by the small-diameter aluminum alloy tubing during deformation divides the original carbon fiber aluminum alloy tubing into multiple small areas, increasing the overall buckling load of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a flow chart of the forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes of the present invention;

[0051] Figure 2 This is a diagram of the pre-processing steps of the forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes of the present invention;

[0052] Figure 3 This is a forming process diagram of the composite integration method for forming a carbon fiber reinforced aluminum alloy sandwich tube according to the present invention;

[0053] Figure 4 This is a detailed diagram of the pre-compounding method for forming and composite integration of carbon fiber reinforced aluminum alloy sandwich tubes according to the present invention;

[0054] Figure 5 This is a detailed diagram of the composite forming method for forming a carbon fiber reinforced aluminum alloy sandwich tube according to the present invention. DETAILED DESCRIPTION

[0055] To fully describe the technical content, structural features, objectives and effects of the present invention, the following is a detailed description with reference to the accompanying drawings.

[0056] The forming composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes involves a small-diameter aluminum alloy pipe 1, carbon fiber 2, a medium-diameter aluminum alloy pipe 3, a large-diameter aluminum alloy pipe 4, a feeding device 5, an axial compression press head 6, a first forming mold 7, an ultrasonic device 8, a spring group 9, a spring group 10, a press 11, a second forming mold 12, a pad 13, a pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminate pipe 14, a stud 15, solid particles 16, bolts 17 and a composite carbon fiber reinforced nickel-plated aluminum alloy laminate pipe 18.

[0057] Forming composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes Figure 1 , Figure 2 and Figure 3 The specific implementation steps are as follows:

[0058] S1. Carbon fibers with different laying directions are plated with nickel layers to prepare nickel-plated carbon fibers.

[0059] S2. Wrapping and stacking the aluminum alloy tube and carbon fiber along the radial direction of the aluminum alloy tube to prepare an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0060] S3. Assemble a solid particle expansion forming mold to obtain a forming mold for compounding.

[0061] S4, such as Figure 4 As shown, according to the temperature required for the composite reaction of the nickel layer and the aluminum alloy Ni / Al→NiAl3→Ni2Al3, the forming mold used for the composite is heated to 200-300°C and the temperature is kept constant.

[0062] S5. According to the local buckling bearing capacity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, continue to apply a pressure of 0-10 MPa to the carbon fiber reinforced nickel-plated aluminum alloy tube, maintain the pressure for 0-1 minute, and perform ultrasonic vibration to obtain a pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0063] S6. Based on S5, the temperature of the solid particles in the forming mold used for compounding is heated to 400-500°C, preferably 450-500°C, and the temperature is kept constant. The insulation temperature is preferably 450-500°C. The same ultrasonic vibration is continued to be applied by the axial compression head to extrude the solid particles to form the pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminated tube. The forming pressure is 20-30 MPa and the forming time is 2-3 min, so that the carbon fiber reinforced nickel-plated aluminum alloy laminated tube is completely fitted with the rigid die in the forming mold to obtain a laminated tube with a preset shape.

[0064] S7, such as Figure 5As shown in the figure, after the carbon fiber reinforced nickel-plated aluminum alloy laminate tube is formed, the holding pressure is 20-30 MPa and the holding time is 40-50 min; then the temperature of the solid particles and the forming mold is kept unchanged at 475-500 ° C, the pressure is reduced to 0 MPa, and the pressure reduction treatment time is preferably 10 to 20 minutes, and more preferably 14 to 16 minutes. The induction heating device is turned off, and the solid particles and the forming mold are cooled and then the mold is opened to remove the part, thereby obtaining the composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube, which effectively improves the forming accuracy and forming quality of the carbon fiber reinforced nickel-plated aluminum alloy tubular component.

[0065] Furthermore, the method for preparing nickel-plated carbon fiber in step S1 includes:

[0066] S11. Place the carbon fiber in a box-type resistance furnace at a temperature of 400°C and heat for 30 minutes to remove the glue.

[0067] S12, washing the debonded carbon fiber with water, placing it in nitric acid for roughening, and then washing it with water again after roughening.

[0068] S13, electroplating the carbon fiber obtained in S12 to obtain nickel-plated carbon fiber.

[0069] Specifically, the plating solution is a mixture of 250g / L NiSO4·6H2O, 10g / L NaCl, 30g / L H3BO3 and 80g / L Na2SO4, stirred evenly, and the pH value is controlled at 5; the current density of the electroplating is 0.2-0.4A / dm 2 , the electroplating time is 2-8min.

[0070] Furthermore, the specific steps of preparing the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube in step S2 are:

[0071] S21. Lay the nickel-plated carbon fiber in layers, and determine the wrapping method of the nickel-plated carbon fiber according to the angle between the 0° carbon fiber tow and the axis of the aluminum alloy pipe when the laid nickel-plated carbon fiber cloth is rolled into a tube.

[0072] Specifically, the nickel-plated carbon fiber is laid in a 0 / 90 / 0 manner, and the nickel-plated carbon fiber is wrapped around the inner tube in such a way that the direction of the 0° carbon fiber tow is parallel to the axis of the aluminum alloy tube.

[0073] S22. Cut out nickel-plated carbon fibers with an area equal to the side wall area of ​​the inner tube of the small-diameter aluminum alloy tube, and wrap the nickel-plated carbon fibers around the outer side of the small-diameter aluminum alloy tube.

[0074] S23. Place the small-aperture aluminum alloy tube wrapped with nickel-plated carbon fiber in a circular array between the medium-aperture and large-aperture aluminum alloy tubes to obtain an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0075] Specifically, before preparing the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminated tube, the aluminum alloy tube needs to be polished, deoxidized and dried to obtain a pretreated aluminum alloy layered tube.

[0076] Furthermore, the method for preparing the composite forming mold in step S3 includes:

[0077] S31. Place the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube vertically in a forming mold so that the bottom of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube overlaps with the pad at the bottom of the mold to form a barrel-shaped semi-enclosed space.

[0078] S32. Add solid particles inside the carbon fiber reinforced nickel-plated aluminum alloy laminate tube so that the solid particles fill the entire cavity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, and at the same time raise the temperature to 200-300° C. Preferably, the diameter of the solid particles is 0.3-0.8 mm.

[0079] S33. Apply a surface load to the inner surface of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube to complete the flexible hot pressing of the layer tube. Use an axial compression punch with a pressure of 0-10 MPa accompanied by ultrasonic vibration to press from the top of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube to form a completely enclosed space inside the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, thereby obtaining a forming mold for composite.

[0080] In a preferred embodiment of the present invention, the aluminum alloy tube is an ordinary aluminum alloy tube or a rare earth aluminum alloy tube of different diameters, preferably a solid solution aluminum alloy tube; the carbon fiber is preferably a T700 type orthogonal laying cloth; the solid particle medium is preferably silicon nitride ceramic balls and molybdenum disulfide particles, and the solid particle diameter is preferably between 0.3 and 0.5 mm.

[0081] Furthermore, the specific process of solving the local bearing capacity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube in step S5 includes:

[0082] According to the moment theory of cylindrical thin shells, the maximum deformation point of the pipe is selected, which is also the first deformation and initial yield point. The internal force expression is solved as follows:

[0083] F1| x＝0 =0

[0084]

[0085]

[0086] Among them, X1=ch 2β+cos 2β, X2=sh 2β-sin 2β, X3=ch 2β-cos 2β, Y1=cosβshβ-sinβchβ, Y2=cosβshβ+sinβchβ.

[0087] Using the third theoretical strength, when the first principal stress is equal to the yield stress, the pipe begins to deform and enters the plastic stage from the elastic stage. The internal pressure value is:

[0088]

[0089] Where F1 is the axial force, F2 is the tangential force, M2 is the bending moment, and p is the internal pressure of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube. μ is the Poisson's ratio of the material, δ is the thickness of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, a is the outer radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, l is the total length of the free deformation zone, ps is the internal pressure value of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube from the elastic stage to the plastic stage, σ s is the yield stress, A and B are functions of β.

[0090] Furthermore, the specific process of solving the stress analysis and forming force of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube in step S5 includes:

[0091] At any moment when the deformation zone is deforming, a typical unit C at the center of the convex ring is taken for analysis. Projecting the forces on the infinitesimal element radially and listing the equilibrium equations, we can obtain:

[0092]

[0093] Where, σ θ is the hoop stress; σ t is the meridian tangential stress; p is the internal pressure of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube; ρ θ is the annular curvature radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube; ρ t is the meridian curvature radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube; δ is the thickness of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0094] ρ θ =R0+(R1+ρ t )(1-cosγ)

[0095]

[0096] Where, ρ θ is the annular curvature radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube; ρ tis the meridian curvature radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube; R0 is the inner radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube; R1 is the outer radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube after forming; R2 is the inner radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube after forming; γ is the central angle of the free deformation zone.

[0097] At any moment of forming, the equivalent stress satisfies:

[0098]

[0099] Where, σ θ is the hoop stress; σ t It is the tangential direction of the meridian plane; is the equivalent stress.

[0100] Therefore, the isotropic stress and forming internal pressure at the typical unit C can be obtained as follows:

[0101]

[0102]

[0103]

[0104] Where, σ θ is the hoop stress; σ t It is the tangential direction of the meridian plane; is the equivalent stress; P is the internal pressure during the forming of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; δ is the thickness of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; R0 is the inner radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; R1 is the outer radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube after forming; R2 is the inner radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube after forming; γ is the central angle of the free deformation zone.

[0105] The following further describes a forming and composite integration method for a carbon fiber reinforced aluminum alloy sandwich tube according to the present invention in conjunction with an embodiment:

[0106] Example 1

[0107] S1. Carbon fibers with different laying directions are plated with nickel layers to prepare nickel-plated carbon fibers.

[0108] S11. Place the carbon fiber in a box-type resistance furnace and heat it at 400°C for 30 minutes to remove the glue.

[0109] S12, washing the debonded carbon fiber with water and then placing it in nitric acid for coarsening, and then washing it with water for a second time after coarsening.

[0110] S13. Fix the carbon fiber with a copper rod and place it in an electroplating tank as a cathode. Then put two copper rods and hang a pure nickel plate on it as an anode for electroplating. After the electroplating is completed, dry it to obtain nickel-plated carbon fiber with a thickness of 0.25 mm.

[0111] S2. Wrap and stack the aluminum alloy tube and the carbon fiber along the radial direction of the carbon fiber to prepare an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0112] S21. Lay T700 type nickel-plated carbon fiber in orthogonal directions with a laying method of 0 / 90 / 0. Determine the wrapping method of the nickel-plated carbon fiber based on the angle between the 0° carbon fiber tow and the axis of the aluminum alloy pipe when the laid nickel-plated carbon fiber cloth is rolled into a tube.

[0113] S22. Cut out nickel-plated carbon fiber with an area equal to the side wall of the inner tube of the small-diameter aluminum alloy tube, and wrap it around the outside of the small-diameter aluminum alloy tube so that the direction of the 0° nickel-plated carbon fiber tow is parallel to the axis of the aluminum alloy tube.

[0114] S23. Place the small-aperture aluminum alloy tube wrapped with nickel-plated carbon fiber in a circular array between the medium-aperture and large-aperture aluminum alloy tubes to obtain an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0115] S3. Assemble a solid particle expansion forming mold to obtain a forming mold for compounding.

[0116] S31. Place the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube vertically in a forming mold so that the bottom of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube overlaps with the pad at the bottom of the mold to form a barrel-shaped semi-enclosed space.

[0117] S32. Add solid particles inside the carbon fiber reinforced nickel-plated aluminum alloy laminate tube so that the solid particles fill the entire cavity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube. The interior of the formed part is solid particles. The diameter of the solid particles is 0.1mm silicon nitride ceramic balls and molybdenum disulfide. At the same time, heat it to 200-300℃.

[0118] S33. Place an axial compression head above the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube, connect the axial compression head and the feeding device with spring group A, and connect the feeding device and the first forming mold with spring group B to ensure that the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube does not move axially before expansion. Initially press in the axial compression head with a pressure of 0-10Mpa to form a completely enclosed space inside the carbon fiber reinforced nickel-plated aluminum alloy laminate tube to obtain a forming mold for compounding.

[0119] S4. According to the temperature required for the composite reaction of nickel layer and aluminum alloy Ni / Al→NiAl3→Ni2Al3, the carbon fiber reinforced nickel-plated aluminum alloy laminated tube, forming mold and solid particles are preliminarily heated. After the forming mold used for composite is heated to 200-300°C, the temperature is kept constant for 3 minutes and the holding time is 5 minutes to allow the aluminum alloy tube and nickel to fully react.

[0120] S5. According to the local buckling bearing capacity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, continue to apply a pressure of 0-10 MPa to the carbon fiber reinforced nickel-plated aluminum alloy tube and maintain the pressure for 0-1 minute while accompanied by ultrasonic vibration to obtain a pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0121] S6. Based on S5, the pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminated tube, the axial compression head, the forming mold for composite and the solid particles are heated to 400-500°C, the temperature is kept constant, the heating time is 3 minutes, and the pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminated tube is formed by continuing to extrude the solid particles using the axial compression head. The forming pressure is 20-30 MPa and the forming time is 2-3 minutes. At the same time, ultrasonic vibration auxiliary treatment is applied to the solid particle medium. The solid particles on the inner surface of the aluminum alloy tube provide internal pressure during the forming process of the aluminum alloy tube, so that the carbon fiber reinforced nickel-plated aluminum alloy laminated tube is completely fitted with the rigid die in the forming mold to obtain a laminated tube with a preset shape.

[0122] In step S7, the solid particle medium and the forming mold temperature are maintained constant, and the solid particle pressure on the upper surface of the carbon fiber reinforced rare earth aluminum alloy laminated tube component is gradually reduced to 0 MPa. The induction heating device is turned off, and after the solid particle medium and the forming mold have cooled, the mold is opened and the component is removed, thereby obtaining a carbon fiber reinforced nickel-plated rare earth aluminum alloy component.

[0123] S8. After the carbon fiber reinforced nickel-plated aluminum alloy laminate tube is formed, continue to carry out heat preservation and pressure treatment, the heat preservation temperature is 450-500℃, the heat preservation time is 30-60min, and the nickel layer on the surface of the carbon fiber is completely compounded with the aluminum alloy tube; then keep the temperature of the solid particles and the forming mold unchanged at 475-500℃, gradually reduce the pressure of the solid particles on the upper surface of the carbon fiber reinforced nickel-plated aluminum alloy tube component to 0MPa, turn off the induction heating device, and after the solid particles and the forming mold are cooled, open the mold and take out the part to obtain the compounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0124] Example 2

[0125] S1. Carbon fibers with different laying directions are plated with nickel layers to prepare nickel-plated carbon fibers.

[0126] S11. Place the carbon fiber in a box-type resistance furnace and heat it at 400°C for 30 minutes to remove the glue.

[0127] S12, washing the debonded carbon fiber with water and then placing it in nitric acid for coarsening, and then washing it with water for a second time after coarsening.

[0128] S13, fixing the carbon fiber with a copper rod, placing it in an electroplating tank as a cathode, then placing two copper rods and hanging a pure nickel plate as an anode, and electroplating is performed. After the electroplating is completed, drying is performed to obtain nickel-plated carbon fiber with a thickness of 0.1 mm.

[0129] S2. Wrap and stack the aluminum alloy tube and the carbon fiber along the radial direction of the carbon fiber to prepare an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0130] S21. Lay T500 type nickel-plated carbon fiber in orthogonal directions with a laying method of 0 / 90 / 0. Determine the wrapping method of the nickel-plated carbon fiber based on the angle between the 0° carbon fiber tow and the axis of the aluminum alloy pipe when the laid nickel-plated carbon fiber cloth is rolled into a tube.

[0131] S22. Cut out nickel-plated carbon fiber with an area equal to the side wall of the inner tube of the small-diameter aluminum alloy tube, and wrap it around the outer side of the inner tube of the aluminum alloy tube so that the direction of the 0° nickel-plated carbon fiber tow is parallel to the axis of the aluminum alloy tube.

[0132] S23. Place the small-aperture aluminum alloy tube wrapped with nickel-plated carbon fiber in a circular array between the medium-aperture and large-aperture aluminum alloy tubes to obtain an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0133] S3. Assemble a solid particle expansion forming mold to obtain a forming mold for compounding.

[0134] S31. Place the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube vertically in a forming mold so that the bottom of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube overlaps with the pad at the bottom of the mold to form a barrel-shaped semi-enclosed space.

[0135] S32. Add solid particles inside the carbon fiber reinforced nickel-plated aluminum alloy laminate tube so that the solid particles fill the entire cavity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube. The interior of the formed part is solid particles. The diameter of the solid particles is 0.15mm silicon nitride ceramic balls and molybdenum disulfide. At the same time, heat it to 200-300℃.

[0136] S33. After the solid particles are fully filled, place an axial compression head above the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube, connect the axial compression head and the feeding device with spring group A, and connect the feeding device and the first forming mold with spring group B to ensure that the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube does not move axially before expansion. Initially press the axial compression head in with a pressure of 0-10MPa to form a completely enclosed space inside the carbon fiber reinforced nickel-plated aluminum alloy laminate tube to obtain a forming mold for compounding.

[0137] S4. According to the temperature required for the composite reaction of nickel layer and aluminum alloy Ni / Al→NiAl3→Ni2Al3, the carbon fiber reinforced nickel-plated aluminum alloy laminated tube, forming mold and solid particles are first preliminarily heated. After the forming mold used for composite is heated to 200-300°C, the temperature is kept constant for 5 minutes of heating and 5 minutes of holding time to allow the aluminum alloy tube and nickel to fully react.

[0138] S5. According to the local buckling bearing capacity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, continue to apply a pressure of 0-10 MPa to the carbon fiber reinforced nickel-plated aluminum alloy tube and maintain the pressure for 0-1 minute while accompanied by ultrasonic vibration to obtain a pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0139] S6. Based on S5, the pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminated tube, the axial compression head, the forming mold for composite and the solid particles are heated to 450-500°C, the temperature is kept constant, the heating time is 2 minutes, and the pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminated tube is formed by continuously extruding the solid particles using the axial compression head. The forming pressure is 20-30 MPa and the forming time is 2-3 minutes. At the same time, ultrasonic vibration auxiliary treatment is applied to the solid particle medium. The solid particles on the inner surface of the rare earth aluminum alloy tube provide internal pressure during the forming process of the aluminum alloy tube, so that the carbon fiber reinforced nickel-plated aluminum alloy laminated tube is completely fitted with the rigid concave mold in the forming mold to obtain a laminated tube with a preset shape.

[0140] S7. Maintaining the temperature of the solid particle medium and the forming mold, gradually reduce the solid particle pressure on the upper surface of the carbon fiber reinforced rare earth aluminum alloy laminated tube component to 0 MPa. Turn off the induction heating device, and after the solid particle medium and the forming mold have cooled, open the mold and remove the component, thereby obtaining a carbon fiber reinforced nickel-plated rare earth aluminum alloy component.

[0141] S8. After the carbon fiber reinforced nickel-plated aluminum alloy laminate tube is formed, continue to carry out heat preservation and pressure treatment, the heat preservation temperature is 450-500℃, the heat preservation time is 30-60min, and the nickel layer on the surface of the carbon fiber is completely compounded with the aluminum alloy tube; then keep the temperature of the solid particles and the forming mold unchanged at 475-500℃, gradually reduce the pressure of the solid particles on the upper surface of the carbon fiber reinforced nickel-plated aluminum alloy tube component to 0MPa, turn off the induction heating device, and after the solid particles and the forming mold are cooled, open the mold and take out the part to obtain the compounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

[0142] The room temperature tensile strength, high temperature tensile strength and shear strength between the carbon fiber and the aluminum alloy laminate tube are high, and the room temperature tensile strength reaches 357 MPa.

[0143] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipes, characterized in that: The specific implementation steps are as follows: S1, preparing carbon fiber with nickel layer deposited on the surface; S2. Prepare three aluminum alloy tubes with different inner diameters. Wrap and stack the small-pore aluminum alloy tube with carbon fibers along the radial direction of the aluminum alloy tube and place them in a circular array between the medium-pore aluminum alloy tube and the large-pore aluminum alloy tube to obtain an uncompounded carbon fiber-reinforced nickel-plated aluminum alloy laminate tube. S3. Assemble the solid particle bulging mold and the ultrasonic device to obtain a forming mold for compounding: S31, vertically placing the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube in a forming mold, so that the bottom of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube overlaps with the backing plate at the bottom of the mold, forming a barrel-shaped semi-enclosed space; S32, adding solid particles to the innermost layer of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, so that the solid particles fill the entire cavity of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube; S33, using an axial punch to press into the carbon fiber reinforced nickel-plated aluminum alloy laminate tube from above, forming a closed space inside the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, and then assembling an ultrasonic vibration device on the axial punch to obtain a forming mold for composite; S4. According to the temperature required for the composite reaction between the nickel layer and the aluminum alloy (Ni / Al→NiAl3→Ni2Al3), the forming mold used for composite is heated to 200-300°C and the temperature is kept constant; The free deformation zone of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube in S3 is intercepted. In the unit at the maximum deformation point, the tangential stress is the first principal stress, and the radial force and axial force are close to zero. Using the third theoretical strength, when the first principal stress is equal to the yield stress, the tube begins to deform and enters the plastic stage from the elastic stage. The internal pressure at this time is: Where p s is the internal pressure value when the carbon fiber reinforced nickel-plated aluminum alloy laminated tube enters the plastic stage from the elastic stage, σ s is the yield stress, A and B are functions of β, μ is the Poisson's ratio of the material, δ is the thickness of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, a is the outer radius of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube, and l is the total length of the free deformation zone; At any moment during deformation of the deformation zone, the typical unit C at the center of the convex ring is analyzed and obtained. The isotropic stress and forming internal pressure at the typical unit C are: Where, σ θ is the hoop stress; σ t It is the tangential direction of the meridian plane; is the equivalent stress; P is the internal pressure during the forming of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; δ is the thickness of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; R0 is the inner radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube; R1 is the outer radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube after forming; R2 is the inner radius of the carbon fiber reinforced nickel-plated aluminum alloy laminated tube after forming; γ is the central angle of the free deformation zone; Applying a pressure of 0-10 MPa to the carbon fiber reinforced nickel-plated aluminum alloy tube, maintaining the pressure for 0-1 minute, and performing ultrasonic vibration to obtain a pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube; S5. Based on S4, after heating the temperature of the solid particles in the forming mold for composite to 400-500° C., maintaining the temperature unchanged, continue to use the axial compression head to apply the same ultrasonic vibration and extrude the solid particles to form the pre-composite carbon fiber reinforced nickel-plated aluminum alloy laminated tube, the forming pressure is 20-30 MPa, and the forming time is 2-3 minutes, so that the carbon fiber reinforced nickel-plated aluminum alloy laminated tube is completely fitted with the rigid concave die in the forming mold, and a carbon fiber reinforced nickel-plated aluminum alloy laminated tube with a preset shape is obtained; S6. After the carbon fiber reinforced nickel-plated aluminum alloy laminate tube is formed, the holding pressure is 20-30 MPa and the holding time is 40-50 minutes; then the pressure is reduced to 0 MPa to obtain the composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

2. The forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipe according to claim 1, characterized in that: The forming raw materials for the carbon fiber aluminum alloy tube forming and composite integration method include a small-diameter aluminum alloy tube, carbon fiber, a medium-diameter aluminum alloy tube, and a large-diameter aluminum alloy tube. The raw materials are placed accordingly and semi-compounded to obtain a pre-compounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube, which is then formed again to obtain a composite carbon fiber reinforced nickel-plated aluminum alloy laminate tube. The forming device includes a feeding device, an axial compression ram, a first forming mold, an ultrasonic device, a spring group A, a spring group B, a press, a second forming mold, a pad, studs, solid particles and bolts; after the axial compression ram is installed in the press, it is fixed to the feeding device with the spring group A and bolts, and then the pad, the second forming mold and the first forming mold are placed in sequence according to the corresponding positions, and the first forming mold and the feeding device are fixed with the spring group B and studs. After the raw material pipe is loaded, the solid particles are poured in and the ultrasonic device is installed to achieve pre-composite and composite forming.

3. The forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipe according to claim 1, characterized in that: The specific implementation steps of step S1 include: S11, placing the carbon fiber in a box-type resistance furnace at a temperature of 400°C and heating for 30 minutes to remove the glue; S12, washing the debonded carbon fiber with water, placing it in nitric acid for roughening, and then washing it with water again after roughening; S13, electroplating the carbon fiber obtained in S12 to obtain nickel-plated carbon fiber.

4. The forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipe according to claim 1, characterized in that: The specific implementation steps of step S2 include: S21, laying the nickel-plated carbon fiber, and determining the wrapping method of the nickel-plated carbon fiber according to the angle between the 0° carbon fiber tow and the axis of the aluminum alloy tube when the laid nickel-plated carbon fiber cloth is rolled into a tube; S22, cutting out nickel-plated carbon fibers with an area equal to that of the sidewall of the small-diameter aluminum alloy tube, and wrapping the nickel-plated carbon fibers around the outside of the small-diameter aluminum alloy tube; S23. Place the small-pore aluminum alloy tube wrapped with nickel-plated carbon fiber in a circumferential array between the medium-pore aluminum alloy tube and the large-pore aluminum alloy tube to obtain an uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube.

5. The forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipe according to claim 2, characterized in that: The feeding device, axial compression head, ultrasonic device, first forming mold, spring group A and spring group B constitute a spring axial feeding and feeding structure. By adjusting the stiffness ratio of spring group A and spring group B, the internal pressure of the carbon fiber reinforced nickel-plated aluminum alloy laminate tube from mold closing to uncompounded and the internal pressure of the automatically fed solid particles during pre-compounding and composite forming are both met.

6. The forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipe according to claim 3, characterized in that: In step S2, the nickel-plated carbon fiber is laid in a 0°-90°-0° manner, and the nickel-plated carbon fiber wraps the inner tube in a 0° manner, with the direction of the carbon fiber bundle being parallel to the axis of the aluminum alloy tube.

7. The forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipe according to claim 1 or 3, characterized in that: In step S3 , the ultrasonic vibration device and the axial punch are assembled by means of interference fit.

8. The forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipe according to claim 1, characterized in that: The diameter of the small-diameter aluminum alloy tube in step S2 is 3-5 mm, the diameter of the medium-diameter aluminum alloy tube is 20-30 mm, and the diameter of the large-diameter aluminum alloy tube is 26-40 mm.

9. The forming and composite integration method for carbon fiber reinforced aluminum alloy sandwich pipe according to claim 1, characterized in that: Before preparing the uncompounded carbon fiber reinforced nickel-plated aluminum alloy laminate tube in step S2, the aluminum alloy tube needs to be subjected to electrolytic corrosion treatment and deoxidation and drying treatment to obtain a pretreated aluminum alloy layer tube.

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