Lightweight composite material control arm and manufacturing method therefor

Abstract

Disclosed in the present invention are a lightweight composite material control arm and a manufacturing method therefor. The lightweight composite material control arm comprises a reinforced framework and a coating layer; the reinforced framework is a first metal framework or a second framework comprising a continuous fiber-reinforced thermoplastic composite material framework; the coating layer is a chopped fiber-reinforced thermoplastic composite material coating layer; and the chopped fiber-reinforced thermoplastic composite material coating layer is coated on the surface of the reinforced framework by means of injection molding. In the lightweight composite material control arm and the manufacturing method therefor of the present invention, the overall mechanical properties of a component are improved while lightweight is ensured, the strength is high, the rigidity is high, material combinations can be flexibly configured according to stress requirements, customization and optimization of properties of the control arm are achieved, the design flexibility is high, and the production efficiency is high.

Description

A lightweight composite material control arm and its preparation method Technical Field

[0001] This invention belongs to the field of vehicle suspension devices, and particularly relates to a control arm and its manufacturing method. Background Technology

[0002] Modern cars typically use suspension systems to isolate the passenger compartment from wheel disturbances caused by uneven road surfaces. These suspension systems usually include control arms, which are components that connect the steering knuckle to the front axle of the car. They are used to transmit torque to the front axle to steer the vehicle and bear various loads during vehicle operation. Their strength and stiffness have a decisive impact on the overall vehicle performance.

[0003] Traditional control arms are made entirely of metal, resulting in heavy weight and complex molding processes. Currently, lightweight control arms based on composite materials use metal joints only at the connection points to significantly reduce weight. While these composite control arms offer substantial weight reduction, they also reduce the stiffness of the control arm, making it difficult to meet usage requirements.

[0004] Therefore, there is an urgent need for a lightweight composite material control arm that can achieve maximum lightweighting while maintaining high strength and high stiffness. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a lightweight composite material control arm that achieves maximum lightweighting while maintaining high strength and high stiffness, and a method for preparing the same.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0007] A lightweight composite material control arm includes a reinforcing skeleton and a covering layer. The reinforcing skeleton is a first metal skeleton or a second skeleton including a continuous fiber-reinforced thermoplastic composite skeleton. The covering layer is a chopped fiber-reinforced thermoplastic composite covering layer, which is injection molded onto the surface of the reinforcing skeleton.

[0008] In the aforementioned lightweight composite material control arm, preferably, the second skeleton is a composite skeleton formed by hot pressing a continuous fiber-reinforced thermoplastic composite material skeleton and a second metal skeleton into a whole.

[0009] In this invention, the first and second metal skeletons can be the same or different metal skeletons. The material of the metal skeleton can be steel, aluminum, magnesium, or their alloys. The size of the metal skeleton can be much smaller than that of a control arm made of pure metal, and therefore its weight will also be much less than that of a control arm made of pure metal. This invention utilizes a metal skeleton, a continuous fiber reinforced thermoplastic composite skeleton, and a short fiber reinforced thermoplastic composite coating layer with good matching properties. The synergistic effect of each part helps to ensure the mechanical performance of the control arm. Specifically, the metal skeleton provides rigidity and high strength support, serving as the interface for connecting the component to other external structures. The continuous fiber reinforced composite material bears the main structural loads and provides extremely high specific strength and specific stiffness. The short fiber injection molded composite material is molded into complex geometries, connects different materials, and provides a functional anti-corrosion layer. This invention fully utilizes the characteristics of the three materials, compensating for their respective shortcomings through synergistic effects. Metal has extremely high plasticity and toughness. When the component is subjected to a huge impact, the metal skeleton can undergo plastic deformation, absorbing a large amount of energy and preventing the component from undergoing catastrophic brittle fracture. Under prolonged loads or high temperatures, plastics are prone to creep (deformation). The intervention of a metal skeleton limits this deformation, ensuring the geometric accuracy of the component for long-term use. Metal materials are prone to fatigue cracking under cyclic loading, while continuous fiber composites typically have a high fatigue life. Combining the two can improve the overall lifespan of the component under alternating loads. Metal skeletons and continuous fiber prepregs are often difficult to fabricate into complex three-dimensional structures (such as reinforcing ribs, snap-fits, and irregular holes). Short fiber injection molding materials have good flowability and can perfectly encapsulate the pre-placed metal parts and continuous fiber layers through injection molding, forming a strong mechanical interlock and chemical bond.

[0010] Preferably, the aforementioned lightweight composite material control arm further includes a metal sleeve for mounting a ball pin and a metal tube for mounting a bushing. The first and second metal frames are U-shaped structures that match the shape of the control arm. The top curved section of the U-shaped structure has a through hole. The metal sleeve is fixed at the through hole, and the metal tube is fixed at both ends of the U-shaped structure. The metal sleeve and metal tube can both be mounted on the first and second metal frames. The welded integral metal frame, metal sleeve, and metal tube can significantly improve the strength and rigidity of the control arm. When a composite frame is used, the placement of the metal sleeve and metal tube should not affect the hot-pressing composite of the continuous fiber-reinforced thermoplastic composite frame and the second metal frame.

[0011] In the aforementioned lightweight composite material control arm, preferably, the outer periphery of the metal sleeve is provided with multiple raised rings, and a rubber filling groove is formed between adjacent raised rings. The through hole abuts against one of the raised rings to achieve positioning of the first metal frame and the metal sleeve before welding, or to achieve positioning of the second metal frame and the metal sleeve before welding. The outer periphery of the metal tube is also provided with multiple raised rings, and a rubber filling groove is formed between adjacent raised rings. The outer periphery of the metal tube is also provided with a slot arranged along its axial direction. The end point of the first metal frame is inserted into the slot to achieve positioning of the first metal frame and the metal tube before welding, or the end point of the second metal frame is inserted into the slot to achieve positioning of the second metal frame and the metal tube before welding. The multiple raised rings on the outer periphery of the metal sleeve can be used to determine the welding position of the metal sleeve and the metal frame, so as to ensure the accuracy of the welding position of the metal sleeve and the metal frame. The slot on the outer periphery of the metal tube allows the end point of the metal frame to be inserted into the slot during welding to achieve positioning of the metal frame and the metal tube before welding, which can also ensure the accuracy of the welding position of the metal tube and the metal frame. Simultaneously, the rubber filling groove formed between adjacent convex rings of the metal sleeve and metal bushing can accommodate the rubber material (resin in the continuous fiber-reinforced thermoplastic composite skeleton or resin mixed in online injection molding), increasing the contact area between the resin and the metal sleeve or metal bushing, and increasing the bonding force between the resin and the metal sleeve or metal bushing. The aforementioned metal bushing can be a standalone bushing or a ball-and-pin housing.

[0012] In the aforementioned lightweight composite material control arm, preferably, the first metal skeleton and / or the second metal skeleton are sheet-like structures, and the edges of the sheet-like structures are flanged to form hollow grooves. The short-cut fiber reinforced thermoplastic composite coating layer covers the hollow grooves and forms a reinforcing rib structure within the hollow grooves. The reinforcing rib structure includes main reinforcing ribs and triangular reinforcing ribs. The main reinforcing ribs are located at the center line of the hollow grooves, and the distances from the main reinforcing ribs to the two sides of the hollow grooves are M1 and M2, respectively, and M1 = M2. The triangular reinforcing ribs are located between the main reinforcing ribs and the edges of the hollow grooves. The intersection points of the triangular reinforcing ribs and the main reinforcing ribs are evenly distributed, and the distance between any two intersection points is M3, satisfying the following relationship: 12 ≤ M3 ≤ 25. The intersection points of the triangular reinforcing ribs and the edges of the hollow grooves are evenly distributed, and the distance between any two intersection points is M4, satisfying the following relationship: 12 ≤ M4 ≤ 20. The aforementioned sheet-like structure with hollow grooves is suitable for both the first and second metal skeletons. When used with the second metal skeleton, the continuous fiber-reinforced thermoplastic composite skeleton can be hot-pressed onto the side of the second metal skeleton away from the hollow grooves. The aforementioned reinforcing rib structure includes main reinforcing ribs and triangular reinforcing ribs. Through this arrangement, in conjunction with the first metal skeleton or composite skeleton, it helps to improve the product's stiffness and buckling resistance.

[0013] In the aforementioned lightweight composite material control arm, preferably, the first metal skeleton and / or the second metal skeleton are provided with multiple through holes for the flow of adhesive material, the diameter of which is 2-5 mm. During injection molding, the adhesive material can flow through the small holes, promoting the flow of the injection molten material, reducing the impact of the adhesive material on the metal skeleton, and simultaneously forming a mechanical interlocking structure to improve the interfacial bonding strength between the metal skeleton and the composite material.

[0014] In the aforementioned lightweight composite material control arm, preferably, the chopped fiber reinforced thermoplastic composite coating layer is completely coated onto the surface of the reinforcing skeleton via online hybrid injection molding. The maximum thickness of the coating layer and reinforcing ribs formed by the chopped fiber reinforced thermoplastic composite material coating onto the surface of the reinforcing skeleton does not exceed 8 mm, in order to reduce the risk of localized voids in the fibers caused by resin cooling and crystallization shrinkage. In the lightweight composite material control arm of the present invention, the metal skeleton is completely coated with composite material, which can reduce the metal rust prevention treatment process and simplify the manufacturing process.

[0015] In the aforementioned lightweight composite material control arm, preferably, the surfaces of the first metal skeleton and / or the second metal skeleton undergo surface pretreatment to form micro-grooves or arrayed protrusions. This configuration enhances the bonding strength between the metal skeleton and the composite material. When the second metal skeleton is first joined to the continuous fiber-reinforced thermoplastic composite skeleton, the continuous fiber-reinforced thermoplastic composite skeleton fully or partially covers the second metal skeleton, and any uncovered areas can be completely covered during subsequent injection molding.

[0016] In the aforementioned lightweight composite material control arm, preferably, the control arm has a U-shaped structure. The outer periphery is connected from one end to the other by a sequence of straight edge T3-curve S1-straight edge T1-circular arc R1-straight edge T2-curve S2-straight edge T6, and the inner periphery is connected from one end to the other by a sequence of straight edge T4-curve S3-straight edge T5. The control arm is asymmetrical; the ball joint center A of the control arm is offset towards one bushing center B of the control arm, with an eccentric vertical distance G1 of 20-30 mm. The approximate center of curve S3 is offset towards the other bushing center C of the control arm, with an eccentric vertical distance G2 of 3-6 mm. Under advanced braking conditions, the product experiences inconsistent loads; the eccentric structural design of this invention fully utilizes the structure's load-bearing capacity.

[0017] In the aforementioned lightweight composite material control arm, preferably, straight edges T3, T4, T5, and T6 are parallel to each other; the distance between straight edges T3 and T4, and the distance between straight edges T5 and T6, are equal, both being L'; the distance L1 between curve S1 and straight edge T1 and curve S3 gradually increases from the end of the control arm near curve S1 towards the center of the ball pin A; the distance L2 between straight edge T2 and curve S2 and curve S3 gradually increases from the end of the control arm near curve S2 towards the center of the ball pin A, and at equidistant points from both ends of the control arm (i.e., the end near curve S1 and the end near curve S2), L1 > L2; the center of arc R1 and the center of the ball pin A are on the same straight line AD; the vertical distance L5 from the center of the ball pin A to arc R1 is equal to the distance from the ball pin of the control arm. The radius r2 of the hole satisfies the following relationship: 10mm≤L5-r2≤18mm (when the product is subjected to force in the direction perpendicular to the line connecting the two bushings, it has a significant impact on the product's rigidity; it is recommended to take the upper limit under permissible conditions); the difference between the vertical distance L4 from the center A of the ball pin to the lower curve S3 and the radius r2 of the ball pin hole of the control arm satisfies the following relationship: L4-r2≥25mm (when the product is subjected to force in the direction perpendicular to the line connecting the two bushings and when the ball pin is pressed in, this is a weak point of the product under stress, and a certain coating thickness needs to be ensured. In addition, it also affects the product's rigidity; it is recommended to take the upper limit under permissible conditions); the arm width of the two arms of the control arm at the bushing of the control arm is L3, which satisfies the following relationship with L': L3-L'≤6mm (the above control can prevent the short fiber part from breaking when pressing into the bushing).

[0018] Our research and invention, combined with the first metal skeleton or composite skeleton used in this invention and the aforementioned shape settings, further enhances product strength and rigidity. The control of the aforementioned process parameters helps ensure the mechanical properties of the control arm with its specific shape, and facilitates the effective functioning of the first metal skeleton or composite skeleton in conjunction with the covering layer.

[0019] When the reinforcing skeleton of the present invention is a composite skeleton made of a continuous fiber reinforced thermoplastic composite skeleton and a second metal skeleton by hot pressing, the continuous fiber reinforced thermoplastic composite skeleton does not need to be cut with notches, which would result in discontinuous fibers (if there are notches, after hot pressing, the continuous fibers at the notches will be discontinuous, causing a significant decrease in mechanical properties); the skeleton fibers of the present invention are completely continuous, and can even be locally reinforced in areas of high stress.

[0020] As a general technical concept, the present invention also provides a method for preparing the above-mentioned lightweight composite material control arm, comprising the following steps:

[0021] S1: Prepare the first metal skeleton; or place the shaped continuous fiber layup in the skeleton mold, heat it to the polymerization temperature, inject low viscosity polymer monomer under high pressure, so that it completely impregnates the continuous fiber and initiates anionic polymerization, forming a continuous fiber reinforced thermoplastic composite skeleton in online in-situ polymerization.

[0022] S2: Place the first metal skeleton or the continuous fiber reinforced thermoplastic composite skeleton into an injection mold, and inject short fiber reinforced thermoplastic resin to coat the surface of the first metal skeleton or the continuous fiber reinforced thermoplastic composite skeleton, forming a coating layer.

[0023] More specifically, when the reinforcing skeleton is a composite skeleton made of continuous fiber-reinforced thermoplastic composite material and a second metal skeleton, which are hot-pressed into a single unit, the preparation method of the control arm includes the following steps:

[0024] S1: The shaped continuous fiber layup is placed in the skeleton mold, heated to the polymerization temperature, and low-viscosity polymeric monomers are injected under high pressure to completely impregnate the continuous fibers and initiate anionic polymerization. The continuous fiber reinforced thermoplastic composite skeleton is formed by online in-situ polymerization. The continuous fiber reinforced thermoplastic composite skeleton is then hot-pressed with the second metal skeleton in the molten state to form a composite skeleton.

[0025] S2: The composite skeleton is placed into an injection mold, and short-cut fiber reinforced thermoplastic resin is injected through an online mixing device to completely cover the surface of the first metal skeleton or the composite skeleton, forming a coating layer.

[0026] In the above preparation method, preferably, in the continuous fiber reinforced thermoplastic composite skeleton, the weight content of the continuous fiber is 40%-70%, and the continuous fiber includes a fabric made of at least one of glass fiber, carbon fiber and basalt fiber, with 5-7 layers, and an additional 1-2 layers in the stress concentration area.

[0027] In the above preparation method, preferably, the low-viscosity polymeric monomer is a lactam, which is heated to 160±20℃ and dehydrated under vacuum before injection; the low-viscosity polymeric monomer is divided into two components, A and B, with a catalyst and a co-catalyst added respectively, and simultaneously injected into the mold cavity under high pressure for in-situ polymerization; the weight ratio of component A to catalyst is 1000:3-5, and the catalyst is at least one of sodium hydroxide, potassium hydroxide, and sodium ethoxide; the weight ratio of component B to co-catalyst is 93-98:2-3, and the co-catalyst is at least one of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, and lysine diisocyanate; a toughening agent is also added to component B, and the toughening agent is at least one of hydroxyl-terminated polytetrahydrofuran ether, hydroxyl-terminated polyvinyl alcohol, and hydroxyl-terminated polyacryl alcohol. This invention divides a low-viscosity polymerizable monomer into two components, A and B, and adds a catalyst and a co-catalyst to each component. It employs high-pressure injection molding to increase the impregnation time, allowing the monomer to penetrate rapidly under high pressure while maintaining pressure continuously. This process can produce products with good appearance and mechanical properties.

[0028] In the above preparation method, preferably, the injection pressure of the low viscosity polymeric monomer is 10-16 MPa, the injection time is 15-25 s, and the holding pressure is 60 s or more; the polymerization temperature during online in-situ polymerization is 160±10℃, and the polymerization time is 6±2 min.

[0029] In the above preparation method, preferably, when injection molding chopped fiber reinforced thermoplastic resin, the thermoplastic resin and chopped fibers are melt-blended using an online mixing device. The blended melt is temporarily stored in a buffer tank and then directly injected into the mold under high pressure through a piston injection unit. Online mixing and piston injection avoid the shear damage to the fibers caused by traditional screws, preserving the fiber length and thus improving the mechanical properties of the injection-molded part.

[0030] In the above preparation method, preferably, the chopped fiber reinforced thermoplastic resin has a chopped fiber weight content of 20%-65%, a chopped fiber length of 1-30mm, and a matrix resin including at least one of PA6, PA66, and PP; when directly injected into the mold under high pressure through a piston injection unit, the injection temperature is 40°C or higher than the resin melting point, and the injection pressure is ≥100Bar.

[0031] In the above preparation method, preferably, the diameter of the mold hot runner and injection hole is not less than 2 mm, so as to reduce fiber adhesion to the wall and improve melt flowability.

[0032] In the above preparation method, preferably, after injection molding, the part is subjected to online dimensional inspection based on machine vision or laser scanning, and compared in real time with a digital twin model. Quality monitoring and process feedback adjustment are performed on the edge thickness and reinforcing rib positions in key areas. During the in-situ polymerization or injection molding process, pressure and temperature sensors are integrated inside the mold cavity to monitor the resin flow front, impregnation state, and polymerization reaction progress in real time, achieving closed-loop dynamic control of process parameters.

[0033] Compared with the prior art, the advantages of the present invention are as follows:

[0034] The lightweight composite material control arm and its preparation method of the present invention integrate the performance advantages of heterogeneous materials. It innovatively uses a metal material as a skeleton and then injects fiber-reinforced thermoplastic resin to achieve the integration of skeleton coating, reinforcing rib forming and heterogeneous materials. Alternatively, it uses a continuous fiber composite material as a skeleton (more preferably integrated with a metal material through hot pressing) and then injects fiber-reinforced thermoplastic resin to achieve the integration of skeleton coating, reinforcing rib forming and heterogeneous materials. The product obtained by the above process has high specific strength provided by continuous fibers, toughness and ductility provided by metal, and connection and functional integration of injection molding material. The components work synergistically to improve the overall mechanical properties of the component while ensuring lightweight, resulting in high strength and high stiffness. The material combination can also be flexibly configured according to the stress requirements to achieve customization and optimization of control arm performance, resulting in high design flexibility and high production efficiency. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 is a front structural schematic diagram of the lightweight composite material control arm of the present invention.

[0037] Figure 2 is a schematic diagram of the back structure of the lightweight composite material control arm of the present invention.

[0038] Figure 3 is a schematic diagram of the structure of the first metal skeleton / second metal skeleton in the lightweight composite material control arm of the present invention.

[0039] Figure 4 is a schematic diagram of the metal sleeve in the lightweight composite material control arm of the present invention.

[0040] Figure 5 is a schematic diagram of the metal sleeve in the lightweight composite material control arm of the present invention.

[0041] Figure 6 is a schematic diagram of the reinforcing rib structure of the lightweight composite material control arm of the present invention.

[0042] Figure 7 shows a stress comparison analysis of lightweight composite material control arms with different designs.

[0043] Figure 8 is a schematic diagram of the external structure of the lightweight composite material control arm of the present invention.

[0044] Figure 9 is a schematic diagram of the external structure of the lightweight composite material control arm of the present invention.

[0045] Figure 10 is a schematic diagram illustrating the effect of changing the value of L5-r2 on product performance in this invention.

[0046] Figure 11 is a schematic diagram illustrating the effect of changing the value of L4-r2 on product performance in this invention.

[0047] Legend: 1. First metal skeleton; 101. Through hole; 102. Hollow groove; 103. Through hole; 2. Short fiber reinforced thermoplastic composite coating layer; 3. Metal sleeve; 4. Metal tube; 5. Main reinforcing rib; 6. Triangular reinforcing rib; 7. Raised ring; 8. Adhesive filling groove; 9. Slot. Detailed Implementation

[0048] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0049] It should be noted that when a component is described as being "fixed to, attached to, connected to or connected to" another component, it can be directly fixed to, attached to, connected to or connected to the other component, or it can be indirectly fixed to, attached to, connected to or connected to the other component through other intermediate connectors.

[0050] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0051] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0052] Example 1:

[0053] As shown in Figures 1 and 2, the lightweight composite material control arm of this embodiment includes a reinforcing skeleton and a covering layer. The reinforcing skeleton is a composite skeleton formed by hot pressing a continuous fiber reinforced thermoplastic composite skeleton and a second metal skeleton (in this embodiment, the same metal skeleton as in Embodiment 2 can be used, specifically steel) into a whole. The covering layer is a chopped fiber reinforced thermoplastic composite covering layer 2, which is completely covered on the surface of the reinforcing skeleton by online hybrid injection molding.

[0054] In this embodiment, the use of the short fiber reinforced thermoplastic composite coating layer 2 can eliminate the need for anti-corrosion treatment of the metal skeleton, significantly reducing the product production cycle and cost; it can also increase the reliability and strength of the bond between the metal and the composite material; through this coating structure, metal materials that were originally difficult to use in the skeleton due to corrosion, such as magnesium, can be directly used in this embodiment, which has a further effect on lightweighting and cost reduction.

[0055] In this embodiment, it also includes a metal sleeve 3 for installing the ball pin and a metal sleeve 4 for installing the bushing. The shape of the second metal frame is a U-shaped structure that matches the shape of the control arm. The top curved section of the U-shaped structure is provided with a through hole 101. The metal sleeve 3 is fixed at the through hole 101, and the metal sleeve 4 is fixed at the two ends of the U-shaped structure.

[0056] As shown in Figures 3, 4, and 5, in this embodiment, the outer periphery of the metal sleeve 3 is provided with two protruding rings 7, and an adhesive filling groove 8 is formed between adjacent protruding rings 7. The through hole 101 is abutted against one of the protruding rings 7 to achieve positioning of the second metal skeleton and the metal sleeve 3 before welding. The outer periphery of the metal sleeve 4 is provided with two protruding rings 7, and an adhesive filling groove 8 is formed between adjacent protruding rings 7. The outer periphery of the metal sleeve 4 is also provided with a slot 9 arranged along its axial direction. The end of the second metal skeleton is inserted into the slot 9 to achieve positioning of the second metal skeleton and the metal sleeve 4 before welding.

[0057] In this embodiment, the second metal skeleton is a sheet-like structure, and the edge of the sheet-like structure is provided with a flange to form a hollow groove 102. The short-cut fiber reinforced thermoplastic composite coating layer 2 covers the hollow groove 102 and forms a reinforcing rib structure inside the hollow groove 102. As shown in Figure 6, the reinforcing rib structure includes a main reinforcing rib 5 and a triangular reinforcing rib 6. The main reinforcing rib 5 is located at the center line of the hollow groove 102, and the distances from the main reinforcing rib 5 to the two sides of the hollow groove 102 are M1 and M2, respectively, and M1 = M2. The triangular reinforcing rib 6 is located between the main reinforcing rib 5 and the edge of the hollow groove 102. The intersection points of the triangular reinforcing rib 6 and the main reinforcing rib 5 are evenly distributed, and the distance between each pair of intersection points is M3, and satisfies the following relationship: 12 ≤ M3 ≤ 25. The intersection points of the triangular reinforcing rib 6 and the edge of the hollow groove 102 are evenly distributed, and the distance between each pair of intersection points is M4, and satisfies the following relationship: 12 ≤ M4 ≤ 20. The reinforcing rib structure in this embodiment can reduce local stress and improve stiffness. For specific verification results, please refer to the simulation analysis comparison results in Figure 7.

[0058] To verify the effectiveness of the main reinforcing rib 5 and the chopped fiber reinforced thermoplastic composite coating layer 2 in this embodiment, three different structural schemes were designed, as follows: Scheme 1: Main reinforcing rib 5 is omitted, and everything else remains the same; Scheme 2: Main reinforcing rib 5 is included, but the chopped fiber reinforced thermoplastic composite coating layer 2 does not completely cover the metal skeleton; Scheme 3: The scheme in the above embodiment. Stress comparison analysis was performed on the three schemes under the same load conditions (two conditions). Translational loads (unit: N) and rotational loads (unit: N·mm) in three directions were applied to the ball pin center A, bushing center B, and bushing center C, as shown in Table 1 below.

[0059] Table 1: Load data under different working conditions

[0060] The test was conducted according to the test conditions in Table 1 above, and the results are shown in Figure 7. It is clear from Figure 7 that the stress of Scheme 1, which omits the main reinforcing rib 5, and Scheme 2, which does not completely cover the metal skeleton with the short fiber reinforced thermoplastic composite coating layer 2, is significantly higher than that of Scheme 3.

[0061] In this embodiment, the second metal skeleton has multiple through holes 103 for the flow of adhesive material. The diameter of the through holes 103 is 2-5mm. In this embodiment, it can be 2mm. In other embodiments, other values ​​can be selected as needed.

[0062] In this embodiment, the maximum thickness of the coating layer and reinforcing ribs formed by the short fiber reinforced thermoplastic composite material covering the surface of the reinforcing skeleton does not exceed 8 mm. Specifically, it can be 4 mm in this embodiment. In other embodiments, other values ​​can be selected as needed.

[0063] In this embodiment, the surface of the second metal skeleton is pretreated to form micro-grooves or arrays of protrusions.

[0064] As shown in Figures 8 and 9, in this embodiment, the control arm has a U-shaped structure. The outer periphery is connected from one end to the other by a straight edge T3-curve S1-straight edge T1-circular arc R1-straight edge T2-curve S2-straight edge T6. The inner periphery is connected from one end to the other by a straight edge T4-curve S3-straight edge T5. The control arm is not symmetrical. The ball pin center A of the control arm is biased towards the bushing center B of the control arm, with an eccentric vertical distance G1 of 25mm. The approximate center of curve S3 is biased towards the other bushing center C of the control arm, with an eccentric vertical distance G2 of 4mm.

[0065] In this embodiment, straight edges T3, T4, T5, and T6 are parallel to each other; the distance between straight edges T3 and T4, and the distance between straight edges T5 and T6, are equal, both being L'; the distance L1 between curve S1 and straight edge T1 and curve S3 gradually increases from the end of the control arm near curve S1 towards the center A of the ball pin; the distance L2 between straight edge T2 and curve S2 and curve S3 gradually increases from the end of the control arm near curve S2 towards the center A of the ball pin, and at equal distances from the end of the control arm, L1 > L2 (0 < L2 < L3). (Between -10mm); The center of arc R1 and the center of the ball pin A are on the same straight line AD. The vertical distance L5 from the center of the ball pin A to arc R1 and the radius r2 of the ball pin hole of the control arm satisfy the following relationship: L5-r2=15mm; The difference between the vertical distance L4 from the center of the ball pin A to the lower curve S3 and the radius r2 of the ball pin hole of the control arm satisfies the following relationship: L4-r2=38.8mm; The arm width L3 at the bushing of the control arm on both sides satisfies the following relationship with L': L3-L'=4mm. Curves S1, S2, and S3 are all composed of several tangent arcs.

[0066] In other embodiments, the displacement-load relationship of the product is shown in Figures 10 and 11 by changing the values ​​of L5-r2 and L4-r2. A comparison shows that controlling the values ​​of L5-r2 and L4-r2 to satisfy 10mm≤L5-r2≤18mm and L4-r2≥25mm is more beneficial for improving the mechanical performance of the control arm.

[0067] The method for preparing the lightweight composite material control arm described in this embodiment includes the following steps:

[0068] S1: The shaped continuous fiber layup is placed in a skeleton mold, heated to the polymerization temperature, and a low-viscosity polymeric monomer is injected under high pressure to completely impregnate the continuous fiber, initiating anionic polymerization. This online in-situ polymerization forms a continuous fiber-reinforced thermoplastic composite skeleton. The surface of the second metal skeleton undergoes surface pretreatment to form micro-grooves or arrayed protrusions. The continuous fiber-reinforced thermoplastic composite skeleton is then hot-pressed with the second metal skeleton in a molten state to form a unified composite skeleton. The continuous fiber content is 60% by weight, the continuous fiber is glass fiber, the layup is 6 layers, and an additional layer is added in the stress concentration area. The low-viscosity polymeric monomer is lactam. The monomers were heated to 150°C and dehydrated under vacuum before injection. The low-viscosity monomers were divided into two components, A and B, with catalyst and co-catalyst added to each component respectively. They were simultaneously injected into the mold cavity under high pressure for in-situ polymerization. The weight ratio of component A to catalyst was 1000:3, and the catalyst was sodium hydroxide. The weight ratio of component B to co-catalyst was 97:3, and the co-catalyst was toluene diisocyanate. A toughening agent, hydroxyl-terminated polytetrahydrofuran ether, was also added to component B. The injection pressure of the low-viscosity monomers was 15 MPa, the injection time was 20 s, and the holding pressure was maintained for more than 60 s. The polymerization temperature during online in-situ polymerization was 160°C, and the polymerization time was 6 ± 2 min.

[0069] S2: The above-mentioned composite skeleton is placed into the injection mold. The thermoplastic resin and chopped fibers are melt-blended using an online mixing device. The blended melt is temporarily stored in a buffer tank and then injected directly into the mold under high pressure through a piston injection unit, so that it completely covers the surface of the composite skeleton to form a coating layer. In the chopped fiber reinforced thermoplastic resin, the weight content of chopped fibers is 50%, the length of chopped fibers is 20mm, the injection temperature is 290℃, and the injection pressure is 125Bar.

[0070] Example 2:

[0071] The lightweight composite material control arm of this embodiment differs from that of Embodiment 1 mainly in that a first metal skeleton 1 is used instead of a composite skeleton. The other structures are the same as those of Embodiment 1, and the structures of the first metal skeleton 1 and the second metal skeleton are the same.

[0072] The method for preparing the lightweight composite material control arm described in this embodiment includes the following steps:

[0073] The first metal skeleton 1 is placed into the injection mold. The thermoplastic resin and chopped fibers are melt-blended using an online mixing device. The blended melt is temporarily stored in a buffer tank and then injected directly into the mold under high pressure through a piston injection unit, so that it completely covers the surface of the composite skeleton to form a coating layer. In the chopped fiber reinforced thermoplastic resin, the weight content of chopped fibers is 50%, the length of chopped fibers is 20 mm, the injection temperature is 290℃, and the injection pressure is 125 Bar.

[0074] Example 3:

[0075] The main difference between the lightweight composite material control arm in this embodiment and that in Embodiment 1 is that the injection pressure in S2 is 100 Bar.

[0076] Example 4:

[0077] The main difference between the lightweight composite material control arm in this embodiment and that in Embodiment 1 is that the injection temperature in S2 is 270°C.

[0078] Example 5:

[0079] The control arm in this embodiment differs from that in Embodiment 1 mainly in that it only uses a continuous fiber reinforced thermoplastic composite skeleton, that is, the second metal skeleton in the composite skeleton in Embodiment 1 is omitted. The preparation method accordingly omits the hot pressing composite process of the continuous fiber reinforced thermoplastic composite skeleton and the second metal skeleton. Other conditions are the same as in Embodiment 1.

[0080] Example 6:

[0081] The main difference between the control arm in this embodiment and that in Example 1 is that, when preparing the continuous fiber reinforced thermoplastic composite skeleton, the low viscosity polymer monomers were not divided into two components, A and B. Instead, the lactam, catalyst, and co-catalyst were directly injected into the mold cavity under high pressure for in-situ polymerization. Other conditions were the same as in Example 1.

[0082] Example 7:

[0083] The main difference between the control arm in this embodiment and that in embodiment 1 is that in S2, a conventional injection molding machine is used for injection instead of online mixing, while other conditions are the same as in embodiment 1.

[0084] The control arms prepared in the above embodiments and comparative examples were subjected to performance tests. Two bushings were fixed, and a load was applied at the ball pin. The positive Y direction was the direction perpendicular to the line connecting the ball pin and the bushing, and the positive X direction was the direction through the center of the ball pin and the width of the L2 arm. The load loading directions were the positive X direction and the positive Y direction, respectively. The fatigue load was a sine wave with a positive X amplitude of 6KN and a positive Y amplitude of 12KN, as shown in Table 2 below.

[0085] Table 2: Performance test data of the control arm in the embodiments and comparative examples

[0086] As shown in Table 2 above, the composite skeleton obtained in Example 1, which is formed by hot-pressing a continuous fiber-reinforced thermoplastic composite skeleton with a second metal skeleton in the molten state, and then covering it with a short-fiber-reinforced thermoplastic composite coating layer 2, exhibits superior performance data for the control arm. In Example 5, the metal skeleton was omitted; in Example 6, the low-viscosity polymer monomers were not separated into components A and B; and in Example 7, a conventional injection molding machine was used. The resulting control arm exhibits worse performance data than the control arm obtained in Example 1.

Claims

1. A lightweight composite material control arm, characterized in that, It includes a reinforcing skeleton and a covering layer. The reinforcing skeleton is a first metal skeleton (1) or a second skeleton including a continuous fiber reinforced thermoplastic composite skeleton. The covering layer is a chopped fiber reinforced thermoplastic composite covering layer (2). The chopped fiber reinforced thermoplastic composite covering layer (2) is injection molded onto the surface of the reinforcing skeleton.

2. The lightweight composite material control arm according to claim 1, characterized in that, The second skeleton is a composite skeleton formed by hot pressing a continuous fiber-reinforced thermoplastic composite skeleton and a second metal skeleton into a whole.

3. The lightweight composite material control arm according to claim 2, characterized in that, It also includes a metal sleeve (3) for installing ball pins and a metal sleeve (4) for installing bushings. The first metal frame (1) and the second metal frame are U-shaped structures that match the shape of the control arm. The top curved section of the U-shaped structure is provided with a through hole (101). The metal sleeve (3) is fixed at the through hole (101), and the metal sleeve (4) is fixed at the two ends of the U-shaped structure.

4. The lightweight composite material control arm according to claim 3, characterized in that, The outer periphery of the metal sleeve (3) is provided with a plurality of protruding rings (7), and a rubber filling groove (8) is formed between adjacent protruding rings (7). The through hole (101) abuts against one of the protruding rings (7) to realize the positioning of the first metal skeleton (1) and the metal sleeve (3) before welding or to realize the positioning of the second metal skeleton and the metal sleeve (3) before welding. The outer periphery of the metal sleeve (4) is provided with a plurality of protruding rings (7), and a rubber filling groove (8) is formed between adjacent protruding rings (7). The outer periphery of the metal sleeve (4) is also provided with a slot (9) arranged along its axial direction. The end of the first metal skeleton (1) is inserted into the slot (9) to realize the positioning of the first metal skeleton (1) and the metal sleeve (4) before welding, or the end of the second metal skeleton is inserted into the slot (9) to realize the positioning of the second metal skeleton and the metal sleeve (4) before welding.

5. The lightweight composite material control arm according to claim 2, characterized in that, The first metal skeleton (1) and / or the second metal skeleton are sheet-like structures, and the edges of the sheet-like structures are flanged to form hollow grooves (102). The short-cut fiber reinforced thermoplastic composite coating layer (2) covers the hollow groove (102) and forms a reinforcing rib structure within the hollow groove (102). The reinforcing rib structure includes a main reinforcing rib (5) and a triangular reinforcing rib (6). The main reinforcing rib (5) is located at the center line of the hollow groove (102), and the distance between the main reinforcing rib (5) and the hollow groove (102) is... 2) The distances between the two sides of the edge are M1 and M2, and M1 = M2; the triangular reinforcing rib (6) is located between the edge of the main reinforcing rib (5) and the hollow groove (102), the intersection points of the triangular reinforcing rib (6) and the main reinforcing rib (5) are evenly distributed, the distance between each pair of intersection points is M3, and the following relationship is satisfied: 12≤M3≤25, the intersection points of the triangular reinforcing rib (6) and the edge of the hollow groove (102) are evenly distributed, the distance between each pair of intersection points is M4, and the following relationship is satisfied: 12≤M4≤20.

6. The lightweight composite material control arm according to claim 2, characterized in that, The first metal skeleton (1) and / or the second metal skeleton are provided with a plurality of through holes (103) for the flow of adhesive material, and the diameter of the through holes (103) is 2-5 mm.

7. The lightweight composite material control arm according to claim 1, characterized in that, The short-fiber reinforced thermoplastic composite coating layer (2) is completely coated on the surface of the reinforcing skeleton by online hybrid injection molding, and the maximum thickness of the coating layer and reinforcing ribs formed by the short-fiber reinforced thermoplastic composite coating on the surface of the reinforcing skeleton does not exceed 8 mm.

8. The lightweight composite material control arm according to claim 2, characterized in that, The surfaces of the first metal skeleton (1) and / or the second metal skeleton are pretreated to form micro-grooves or arrays of protrusions.

9. The lightweight composite material control arm according to claim 1, characterized in that, The control arm has a U-shaped structure. The outer periphery is connected from one end to the other by a straight edge T3-curve S1-straight edge T1-circular arc R1-straight edge T2-curve S2-straight edge T6. The inner periphery is connected from one end to the other by a straight edge T4-curve S3-straight edge T5. The control arm is not symmetrical. The ball pin center A of the control arm is offset towards the bushing center B of the control arm, with an eccentric vertical distance G1 of 20-30mm. The approximate center of curve S3 is offset towards the other bushing center C of the control arm, with an eccentric vertical distance G2 of 3-6mm.

10. The lightweight composite material control arm according to claim 9, characterized in that, Straight edges T3, T4, T5, and T6 are parallel to each other; the distance between straight edges T3 and T4, and the distance between straight edges T5 and T6, are equal, both being L'; the distance L1 between curve S1 and straight edge T1 and curve S3 gradually increases from the end of the control arm near curve S1 towards the center of the ball pin A; the distance L2 between straight edge T2 and curve S2 and curve S3 gradually increases from the end of the control arm near curve S2 towards the center of the ball pin A; the center of arc R1 and the center of the ball pin A are at... On the same straight line AD, the vertical distance L5 from the ball pin center A to the arc R1 and the radius r2 of the ball pin hole of the control arm satisfy the following relationship: 10mm≤L5-r2≤18mm; the difference between the vertical distance L4 from the ball pin center A to the lower curve S3 and the radius r2 of the ball pin hole of the control arm satisfies the following relationship: L4-r2≥25mm; the arm width L3 of the two arms of the control arm at the bushing of the control arm satisfies the following relationship with L': L3-L'≤6mm.

11. A method for preparing a lightweight composite material control arm as described in any one of claims 1-10, characterized in that, Includes the following steps: S1: Prepare the first metal skeleton (1); or place the shaped continuous fiber layup in the skeleton mold, heat it to the polymerization temperature, inject low viscosity polymer monomer under high pressure, so that it is completely impregnated with the continuous fiber and then initiates anionic polymerization, and forms a continuous fiber reinforced thermoplastic composite skeleton through online in-situ polymerization. S2: Place the first metal skeleton (1) or the continuous fiber reinforced thermoplastic composite skeleton into an injection mold, and inject short fiber reinforced thermoplastic resin to coat the surface of the first metal skeleton (1) or the continuous fiber reinforced thermoplastic composite skeleton to form a coating layer.

12. The preparation method according to claim 11, characterized in that, In the continuous fiber reinforced thermoplastic composite skeleton, the weight content of the continuous fiber is 40%-70%, and the continuous fiber includes fabrics made of at least one of glass fiber, carbon fiber and basalt fiber, with 5-7 layers, and an additional 1-2 layers in the stress concentration area.

13. The preparation method according to claim 11, characterized in that, The low-viscosity polymerizable monomer is a lactam, which is heated to 160±20℃ and dehydrated under vacuum before injection. The low-viscosity polymerizable monomer is divided into two components, A and B, with a catalyst and a co-catalyst added to each respectively. They are injected into the mold cavity simultaneously under high pressure for in-situ polymerization. The weight ratio of component A to catalyst is 1000:3-5, and the catalyst is at least one of sodium hydroxide, potassium hydroxide, and sodium ethoxide. The weight ratio of component B to co-catalyst is 93-98:2-3, and the co-catalyst is at least one of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, and lysine diisocyanate. A toughening agent is also added to component B, which is at least one of hydroxyl-terminated polytetrahydrofuran ether, hydroxyl-terminated polyvinyl alcohol, and hydroxyl-terminated polyacryl alcohol.

14. The preparation method according to claim 11, characterized in that, The injection pressure of the low-viscosity polymerizable monomer is 10-16 MPa, the injection time is 15-25 s, and the holding pressure is above 60 s; the polymerization temperature during online in-situ polymerization is 160±10℃, and the polymerization time is 6±2 min.

15. The preparation method according to claim 11, characterized in that, When injection molding chopped fiber reinforced thermoplastic resin, the thermoplastic resin and chopped fibers are melt-blended using an online mixing device. The blended melt is temporarily stored in a buffer tank and then directly injected into the mold under high pressure through a piston injection unit.

16. The preparation method according to claim 15, characterized in that, In the chopped fiber reinforced thermoplastic resin, the weight content of chopped fibers is 20%-65%, and the length of the chopped fibers is 1-30mm; when directly injected into the mold under high pressure through a piston injection unit, the injection temperature is 40℃ or higher than the resin melting point, and the injection pressure is ≥100Bar.

Images