Multilayer automobile light weight pipe and preparation method thereof

Abstract

The application discloses a kind of multilayer automobile light weight pipe and its preparation method, which belongs to the technical field of automobile parts manufacturing, pipe material uses three-layer composite structure: inner layer is aluminum alloy, intermediate layer is continuous carbon fiber reinforced polyether ether ketone composite material, outer layer is stainless steel;Preparation method adopts rotary swaging composite process, under the action of heating and periodic swaging, three-layer material is combined into one;The application realizes significant light weight effect, while ensuring the mechanical properties of pipe, especially suitable for automobile structural parts;Process can realize mass production, cost controllable.

Description

Technical Field

[0001] This application belongs to the field of automotive parts manufacturing technology, and in particular relates to a multi-layer lightweight automotive tubing and its preparation method. Background Technology

[0002] As the global automotive industry transforms towards electrification and intelligentization, lightweighting has become a core technological path to improve vehicle range, handling performance, and energy efficiency. Metal tubing widely used in automotive structural components, such as chassis components, collision avoidance systems, and seat frames, are key areas for weight reduction. Traditional solutions often employ single-material systems, such as high-strength steel. While high-strength steel boasts excellent strength and low cost, its high density (approximately 7.8 g / cm³) and corrosion resistance rely on plating or coatings, still posing a risk of rust over long-term use. Aluminum alloys are lightweight (density approximately 2.7 g / cm³) and corrosion-resistant, but their low modulus of elasticity necessitates larger cross-sectional dimensions in applications requiring high stiffness, negating the weight reduction effect. Stainless steel offers excellent corrosion resistance but is expensive, and its density is similar to carbon steel, resulting in poor lightweighting performance.

[0003] In recent years, composite materials have been regarded as the ideal material for next-generation lightweighting due to their superior specific strength and specific stiffness. However, their large-scale application in automotive structural components still faces bottlenecks: Continuous carbon fiber refers to fibers whose length is comparable to the component size, existing in a continuous form within composite materials. Compared to chopped or long fibers, continuous carbon fiber can transfer loads more effectively, has a high elastic modulus and low density, and possesses excellent lightweighting potential. However, pure carbon fiber composite components still have the following problems in automotive applications: poor impact resistance, especially poor repairability after low-speed collisions; susceptibility to electrochemical corrosion when connected to metal parts; high raw material costs and long molding cycles, making it difficult to meet the needs of mass production in automobiles. Polyetheretherketone (PEEK) is a semi-crystalline, high-performance thermoplastic polymer with a long-term service temperature up to 250°C. It exhibits excellent chemical resistance, is resistant to fuels, lubricants, and various solvents, has outstanding fatigue and creep resistance, inherent flame retardancy (UL94 V-0 rating), low smoke toxicity, and good tribological properties. As a composite matrix, PEEK offers advantages over commonly used thermosetting matrices such as epoxy resins, including remelting and processing capabilities, good impact toughness, and recyclability, making it more aligned with the sustainable development trend of the automotive industry. Current research has attempted to use continuous carbon fiber / PEEK composites in automotive parts, but most of these studies use independent parts that are wound or laid up and then hot-pressed, failing to fully realize their potential for structural complementarity with metals. A small number of studies on metal-composite composite pipes have mostly used bonding or mechanical interlocking methods, resulting in insufficient interlayer bonding strength, especially prone to interface failure under alternating humid heat and vibration loads. In terms of composite processes, traditional rotary forging is mainly used for the reduction and strengthening of single-layer metal tubes. However, it faces challenges when used for multi-layer heterogeneous material composites: the deformation behavior of each layer of material is very different, which can easily lead to uncoordinated deformation between layers, resulting in wrinkles or cracks; thermoplastic composite materials need to be formed under precise temperature control, and traditional rotary forging lacks an effective online temperature control system; how to ensure tight adhesion between layers rather than simple mechanical pressing during high-frequency forging is the key to achieving composites.

[0004] Therefore, developing a multi-layer composite tubular structure that can fully leverage the lightweight potential of continuous carbon fiber / PEEK and achieve high-strength bonding with metal layers, along with a high-efficiency, reliable, and scalable manufacturing process, has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a multi-layer lightweight automotive tubing and its preparation method, so as to solve the technical problems in the prior art where single-layer tubing cannot achieve lightweighting, and multi-layer structures have poor bonding effect and limited application.

[0006] To achieve the above objectives, the technical solution adopted in this application is: to provide a multi-layer lightweight automotive tubing, comprising an inner metal layer, a middle composite layer, and an outer metal layer arranged sequentially from the inside to the outside; The intermediate composite layer consists of continuous carbon fibers and a polyetheretherketone matrix.

[0007] In one embodiment, By weight percentage, continuous carbon fiber accounts for 60-65%, and polyetheretherketone matrix accounts for 35-40%.

[0008] In one embodiment, The inner metal layer and the outer metal layer are selected from one of aluminum alloy, stainless steel, magnesium alloy or titanium alloy, respectively.

[0009] In one embodiment, The thickness of the inner metal layer is 0.8-1.5 mm, the thickness of the middle composite layer is 0.5-0.8 mm, and the thickness of the outer metal layer is 0.5-1.0 mm.

[0010] This application also provides a method for preparing multilayer lightweight automotive tubing, specifically including the following steps: (i) Material pretreatment: The inner metal layer is degreased by alkaline washing and phosphate conversion treatment, and then heated to obtain the pretreated inner metal layer; the continuous carbon fiber and polyether ether ketone matrix are mixed, heated and wound to form the intermediate composite layer, and kept warm for later use; the inner surface of the outer metal layer is sandblasted and chemically etched to obtain the pretreated outer metal layer. (ii) Pre-assembly: The pre-treated inner metal layer, intermediate composite layer and pre-treated outer metal layer are fitted together in sequence, sealed at both ends and vacuumed to obtain the pre-assembled body; (III) Rotary forging composite: The mold is heated, and the pre-assembled part is gradually fed into the mold to start the staged composite process; after the rotary forging composite is completed, multi-layer automotive lightweight pipe is obtained.

[0011] In one embodiment, The specific steps of the phased reconciliation in step (three) are as follows: S1. Preheating: The mold temperature is 180 ℃, the rotation speed is 500 rpm, the mold is superimposed with 10 Hz axial micro-vibration with an amplitude of ±0.05 mm, the feeding speed is 1.0 m / min, the mold closing time is 0.3 s, the opening time is 1.7 s, and the pressure is 10 MPa. S2, Preliminary compounding: mold temperature is 220 ℃, rotation speed is 800 rpm, feeding speed is 0.8 m / min, mold closing time is 0.3 s, opening time is 1.2 s, pressure is 95 MPa; S3, Fully Composite: Mold temperature 250 ℃, rotation speed 1000 rpm, feeding speed 0.6 m / min, mold closing time 0.3 s, opening time 0.9 s, pressure 120 MPa.

[0012] In one embodiment, Step (1) The heating temperature for mixing continuous carbon fiber and polyether ether ketone matrix is ​​300-390 ℃, and the heating temperature for the inner metal layer is 180-250 ℃.

[0013] In one embodiment, When fitting the layers in sequence in step (2), leave an assembly gap of 0.15-0.20 mm between each layer.

[0014] In one embodiment, Step (2) The vacuum pressure is 10 Pa.

[0015] In one embodiment, Step (3) post-processing includes rapid cooling, aging treatment, and calibration.

[0016] This application provides a multi-layer lightweight automotive tubing and its preparation method, which has the following advantages compared with the prior art: 1. The middle layer uses continuous carbon fiber reinforced polyetheretherketone composite material, which has a density much lower than aluminum and steel. Through reasonable thickness matching design, the final composite pipe can achieve a weight reduction of 35-45% compared with pure steel pipe of the same size and stiffness, achieving the goal of lightweighting the material and helping to reduce vehicle fuel consumption or increase the driving range of electric vehicles. In the three-layer structure, the inner aluminum alloy provides basic load-bearing capacity, the outer stainless steel provides surface hardness and dent resistance, and the middle layer provides extremely high specific strength and specific modulus, making the pipe far superior to single metal pipes in axial load-bearing capacity and bending stiffness. This three-layer structure also gives the pipe excellent multi-functional integration. First, integrated corrosion protection: the outer stainless steel provides excellent environmental corrosion resistance, and the middle composite material acts as an insulating barrier, fundamentally eliminating the risk of electrochemical corrosion between aluminum and steel, achieving double protection. Second, vibration reduction and noise reduction: carbon fiber reinforced polyetheretherketone composite material has damping characteristics higher than metals, which can effectively absorb and dissipate structural vibration energy, helping to improve the NVH performance of the whole vehicle. 2. In terms of process, the progressive composite process adopts staged control parameters to coordinate the deformation of three layers of materials with different hardness, avoiding wrinkling, cracking or delamination caused by deformation mismatch. Compared with traditional adhesive composite or processes that require multiple heating and pressurization, the one-step forming process of this application integrates multiple steps such as pretreatment, assembly, heating, pressurization composite and shaping into a continuous process. The process is short, the production efficiency is high, the energy consumption is relatively low, and the unit production cost is reduced, making it suitable for large-scale production. Attached Figure Description

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

[0018] Figure 1 This is a cross-sectional microstructure diagram of the multilayer lightweight automotive tubing of Example 1. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, this application will be further described in detail. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0020] Example 1 A method for preparing a multilayer lightweight automotive tubing, specifically including the following steps: (i) Material pretreatment: The inner metal layer is degreased by alkaline washing and phosphate conversion treatment, and then heated to obtain the pretreated inner metal layer; the continuous carbon fiber and polyether ether ketone matrix are mixed and heated to form the intermediate composite layer, which is then kept warm for later use; the inner surface of the outer metal layer is sandblasted and chemically etched to form the pretreated outer metal layer. S1. Pretreatment of the inner metal layer: The inner metal layer is made of 6061-T6 aluminum alloy tube with the following specifications: inner diameter 34.55 mm, outer diameter 37.05 mm, and wall thickness 1.25 mm. The alkaline washing bath consists of NaOH 50 g / L, Na3PO4 30 g / L, and surfactant OP-10 2 g / L. The aluminum alloy tube is placed in the bath and washed at 60 ℃ for 5 min with 40 kHz ultrasonic assistance. After alkaline washing and degreasing, the tube undergoes a three-stage countercurrent water wash for 2 min at each stage. Then, it is subjected to phosphate conversion treatment at 55 ℃ for 8 min to form a micron-sized porous surface with a pore size of 5 μm. The tube is then dried at 120 ℃ for 10 min, preheated to 180 ℃ and held for 20 min to obtain the pretreated inner metal layer for later use. S2, Intermediate Composite Layer: By weight percentage, 65% continuous carbon fiber (T700 grade) and 35% polyetheretherketone matrix are mixed and heated at 300 ℃ for 30 s, 360 ℃ for 45 s, and 390 ℃ for 90 s. After heating, the mixture is wound into shape: mandrel diameter 37 mm, winding angle 10°, number of winding layers 2 (one layer in each direction), winding speed 1.2 m / min, and compaction pressure: 80 N for the first layer and 120 N for the second layer, to obtain an intermediate composite layer with an inner diameter of 37.2 mm, an outer diameter of 40.4 mm, and a wall thickness of 0.85 mm. S3. Pretreatment of outer metal layer: The outer metal layer is made of 304L stainless steel with the following specifications: inner diameter 38.7 mm, outer diameter 40.0 mm, and wall thickness 0.8 mm. Sandblasting is performed to achieve a roughness of Ra 3.0 μm. Etching is carried out with a mixed acid solution of HCl / HNO3 at 40 ℃ for 3 min, with an etching depth of 10 μm to form an anchor-like structure, thus obtaining the pretreated outer metal layer. (II) Pre-assembly: The pre-treated inner metal layer, intermediate composite layer, and pre-treated outer metal layer are nested in sequence, with a gap between each layer (0.15 mm between the inner and intermediate layers, and 0.20 mm between the intermediate and outer layers). The coaxiality is adjusted using a laser alignment instrument. Both ends are sealed, and a vacuum is drawn to ≤10 Pa. Argon gas is then used for protection, and the gas pressure is maintained at 0.2-0.3 MPa to obtain the pre-assembled body. (III) Rotary forging composite: The mold is heated, and the pre-assembled part is gradually fed into the mold to begin the staged composite process; The rotary forging process is carried out using a rotary forging equipment with a multi-lobed radially opening and closing die. The die is driven by a servo system to rotate at high speed and perform periodic opening and closing actions, and has a built-in induction heating unit. The phased recombination process consists of three steps, as follows: S1. Preheating: The mold is heated to 180 ℃, the initial mold gap is 0.6 mm, the rotation speed is 500 rpm, the mold is superimposed with 10 Hz axial micro-vibration, the amplitude is ±0.05 mm; the feeding speed is 1.0 m / min, the guide wheel pressure is 200 N, and the pre-assembled part begins to open and close periodically after entering the mold by 50 mm. The mold closing time is 0.3 s, the opening time is 1.7 s, the pressure is 10 MPa; the diameter reduction is 0.05 mm. S2, Preliminary compounding: mold temperature 220 ℃, mold gap 0.35 mm, rotation speed 800 rpm, feeding speed 0.8 m / min, guide wheel pressure 300 N; mold closing time 0.3 s, opening time 1.2 s, pressure 95 MPa; diameter reduction 0.15 mm; S3, Fully Composite: Mold temperature 250 ℃, mold gap 0.2 mm, rotation speed 1000 rpm; feeding speed 0.6 m / min, guide wheel pressure 400 N, mold closing time 0.3 s, opening time 0.9 s, pressure 120 MPa; pressure holding after closing 0.5 s, diameter reduction 0.2 mm; Under the high pressure of stages S2 and S3, the polyetheretherketone matrix in the molten state produces viscous flow, fully wetting and embedding itself into the micropores on the surface of the inner and outer metal layers; at the same time, the continuous carbon fibers remain stable under pressure. (IV) Post-processing: Cool the demolded pipe to below 80 ℃ at a cooling rate of 50 ℃ / s; after cooling, age at 150 ℃ for 2 h at a heating rate of 3 ℃ / min, then cool in the furnace to 60 ℃ before unloading; calibrate and straighten, perform rust prevention treatment, and sample testing (cut a 200 mm long pipe section from each production batch for interlaminar shear strength testing, with an average value not less than 25 MPa). After packaging, a multi-layer lightweight automotive pipe with an outer diameter of 39.6 mm and a wall thickness of 2.55 mm (inner layer 1.25 mm, middle composite layer 0.7 mm, outer layer 0.6 mm) is obtained. The microstructure diagram is shown below. Figure 1 As shown.

[0021] Example 2 A multi-layer lightweight automotive tubing includes an inner metal layer, an intermediate composite layer, and an outer metal layer arranged sequentially from the inside out. The intermediate composite layer comprises continuous carbon fiber and polyetheretherketone matrix; by weight percentage, continuous carbon fiber accounts for 60% and polyetheretherketone matrix accounts for 40%; the inner metal layer is aluminum alloy and the outer metal layer is stainless steel; the thickness of the inner metal layer is 0.8 mm, the thickness of the intermediate composite layer is 0.3 mm, and the thickness of the outer metal layer is 0.5 mm.

[0022] Example 3 A multi-layer lightweight automotive tubing includes an inner metal layer, an intermediate composite layer, and an outer metal layer arranged sequentially from the inside out. The intermediate composite layer comprises continuous carbon fiber and polyetheretherketone matrix; by weight percentage, continuous carbon fiber accounts for 65% and polyetheretherketone matrix accounts for 35%; the inner metal layer is a magnesium alloy and the outer metal layer is a titanium alloy; the thickness of the inner metal layer is 1.5 mm, the thickness of the intermediate composite layer is 0.8 mm, and the thickness of the outer metal layer is 1.0 mm.

[0023] Comparative Example 1 Single-layer 304L stainless steel, specifications: outer diameter 40.0 mm, wall thickness 2.9 mm.

[0024] Experimental Example 1 Mechanical property testing: The pipes obtained in Example 1 and Comparative Example 1 were subjected to mechanical property testing, and the results are shown in Table 1. Table 1 Test results of mechanical properties of pipes

[0025] As can be seen from the results in Table 1, the multi-layer lightweight automotive tubing prepared in Example 1 is significantly lighter than traditional steel tubing, has superior tensile strength, and achieves remarkable lightweighting while maintaining a relatively high bending stiffness. This demonstrates that the technical solution achieves a good balance between lightweighting and high performance.

[0026] Application examples The multi-layer lightweight automotive tubing prepared in Example 1 can be used to manufacture automotive seat frame tubing, chassis anti-collision beams, and other automotive applications as needed.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0028] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for producing a multilayer automotive lightweight pipe material, characterized by, Specifically, the following steps are included: (i) Material pretreatment: The inner metal layer is degreased by alkaline washing and phosphate conversion treatment, and then heated to obtain the pretreated inner metal layer; the continuous carbon fiber and polyether ether ketone matrix are mixed, heated and wound to form the intermediate composite layer, and kept warm for later use; the inner surface of the outer metal layer is sandblasted and chemically etched to obtain the pretreated outer metal layer. (ii) Pre-assembly: The pre-treated inner metal layer, intermediate composite layer and pre-treated outer metal layer are fitted together in sequence, sealed at both ends, and vacuumed to obtain a pre-assembled body; (III) Rotary forging composite: The mold is heated, and the pre-assembled part is gradually fed into the mold to start the staged composite process; after the rotary forging composite is completed, multi-layer automotive lightweight pipe is obtained after post-processing. The specific steps of the staged compounding are as follows: S1. Preheating: The mold temperature is 180 ℃, the rotation speed is 500 rpm, the mold is superimposed with 10 Hz axial micro-vibration with an amplitude of ±0.05 mm, the feeding speed is 1.0 m / min, the mold closing time is 0.3 s, the opening time is 1.7 s, and the pressure is 10MPa. S2, Preliminary compounding: mold temperature is 220 ℃, rotation speed is 800 rpm, feeding speed is 0.8 m / min, mold closing time is 0.3 s, opening time is 1.2 s, pressure is 95 MPa; S3, Fully Composite: Mold temperature 250 ℃, rotation speed 1000 rpm, feeding speed 0.6 m / min, mold closing time 0.3 s, opening time 0.9 s, pressure 120 MPa; The continuous carbon fiber comprises 60-65% and the polyetheretherketone matrix comprises 35-40% by weight percentage of the intermediate composite layer.

2. The method for preparing a multi-layer lightweight automotive tubing according to claim 1, characterized in that, The inner metal layer and the outer metal layer are respectively selected from aluminum alloy, stainless steel, magnesium alloy or titanium alloy; the thickness of the inner metal layer is 0.8-1.5 mm, the thickness of the intermediate composite layer is 0.5-0.8 mm, and the thickness of the outer metal layer is 0.5-1.0 mm.

3. The method for preparing a multi-layer lightweight automotive tubing according to claim 1, characterized in that, In step (1), the continuous carbon fiber and polyether ether ketone matrix are heated at a temperature of 300-390 ℃, and the inner metal layer is heated at a temperature of 180-250 ℃.

4. The method for preparing a multi-layer lightweight automotive tubing according to claim 1, characterized in that, When fitting the layers in sequence in step (2), leave an assembly gap of 0.15-0.20 mm between each layer.

5. The method for preparing a multi-layer lightweight automotive tubing according to claim 1, characterized in that, The vacuum pressure in step (ii) is 10 Pa.

6. The method for preparing a multi-layer lightweight automotive tubing according to claim 1, characterized in that, The post-processing described in step (iii) includes rapid cooling, aging treatment, and calibration.

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