Composite material plate spring forming method and system

Abstract

The invention relates to a composite material plate spring forming method and system, belongs to the technical field of automobile parts, and solves the problems of weak interlayer bonding strength, poor fatigue performance, complex manufacturing process and low efficiency of a composite material plate spring in the prior art. A composite material plate spring forming system comprises a plurality of subsystems in continuous operation, namely a fiber cloth weaving system, a blank body heating prepressing forming system, a preformed blank body cutting system, a high-pressure glue injection system and a post-treatment and online detection system which are sequentially transmitted through a manipulator. The fiber cloth weaving system cuts composite fiber cloth into a blank body, the blank body is heated, pre-pressed and formed and then cut into a specified width, the high-pressure glue injection system injects an adhesive into a pre-formed body and solidifies the pre-formed body into a plate spring semi-finished product, and the plate spring semi-finished product is sent out of the system through a mechanical arm after being detected to be qualified through post-treatment. And high-efficiency and low-cost manufacturing of the composite material plate spring is realized.

Description

Technical Field

[0001] The invention relates to the technical field of automobile parts, and in particular to a composite material leaf spring forming method and system. Background Art

[0002] In the field of automotive composite leaf spring manufacturing, efficient and low-cost manufacturing of composite leaf springs is an inevitable development trend. Heavy-duty leaf springs have high performance requirements and harsh operating environments. Based on the need for lightweight heavy-duty leaf springs, high-performance carbon fiber and glass fiber composite materials have become important alternative materials to traditional metal leaf springs due to their light weight, high strength, high stiffness, excellent fatigue resistance and long service life.

[0003] At present, heavy-duty leaf springs are mostly made of high-performance resin-based fiber composite materials, and the molding processes mainly include compression molding, resin transfer molding (RTM) and winding molding. However, these traditional processes have many limitations and cannot meet the modern automotive industry's requirements for efficient, automated and continuous production of composite leaf springs.

[0004] On the one hand, most existing composite material molding processes rely on manual operation or semi-automatic equipment, making it difficult to achieve efficient and continuous automated production. For example, compression molding requires complex mold design and manual layering, while winding molding is limited by the flexibility and shape requirements of the equipment. The limitations of these traditional processes make it difficult for composite leaf spring manufacturing to meet the automation and continuous operation requirements of large-scale production. Although resin transfer molding (RTM) has high design freedom and processing efficiency for products with complex structures, the composite leaf springs prepared by this process have insufficient interlayer bonding, and the resin content has weak bonding at the interface junction, which can easily lead to interlayer fractures, thereby affecting the overall performance of the product.

[0005] On the other hand, the existing technology fails to fully consider the continuous operation and production matching between various processes during the production process, resulting in low production efficiency and increased production costs.

[0006] The shortcomings of existing technologies in automation and continuous operation have severely limited the efficiency and cost control of composite leaf spring manufacturing. Therefore, it is urgent to develop more efficient and flexible automated manufacturing technologies to meet the future automotive industry's demand for lightweight and high performance. Summary of the invention

[0007] In view of the above analysis, the embodiments of the present invention aim to provide a composite leaf spring forming method and system to achieve continuous and automated production of composite leaf springs.

[0008] On the one hand, an embodiment of the present invention provides a composite leaf spring forming system, comprising a plurality of subsystems operating continuously: a fiber cloth weaving system, a blank heating pre-pressing forming system, a preformed blank cutting system, a high-pressure glue injection system, and a post-processing and online detection system, which are sequentially transferred by a robot;

[0009] The fiber cloth weaving system includes a loom and a cutting system arranged at the loom outlet, and the cutting system cuts the composite multi-layer fiber cloth with a width of not less than 1000mm continuously woven by the loom into embryos; the embryo heating and pre-pressing forming system includes a pressing mold and a cooling mold, which are used to preliminarily shape the embryo continuously conveyed by the robot to form a preformed embryo with an arc appearance; the preformed embryo cutting system cuts the preformed embryo into preforms of a specified width; the high-pressure injection system includes a forming mold and a glue injection system, and the adhesive is evenly injected into the preform by continuous high-pressure injection, and a semi-finished leaf spring is obtained after curing; the semi-finished leaf spring is sent to the post-processing and online detection system by the robot for processing and detection, and the qualified leaf spring product is sent out of the forming system by the robot.

[0010] On the other hand, an embodiment of the present invention further provides a composite leaf spring forming method, including preform preparation and injection molding, wherein the preform preparation includes the following steps:

[0011] S1. Weaving of fiber cloth: putting fiber filaments into spindles and installing them on a yarn frame to weave a fiber fabric with 20 to 100 composite layers, and cutting to obtain an embryo with a thickness of 20-80 mm;

[0012] S2, embryo pre-pressing: the embryo of S1 is placed in a pressing mold, heated, and pressed into a pre-formed embryo with a certain curvature. After the pressing is completed, the pre-formed embryo is transferred to a cooling mold to cool and set the shape;

[0013] S3. Preform blank cutting: according to the outer dimensions of the leaf spring product, the preform is cut into preforms of specified width.

[0014] Specifically, the fiber filaments in S1 include one or more of glass fiber, carbon fiber, basalt fiber, aramid fiber, and plant fiber.

[0015] Preferably, the fiber fabric in S1 has a width of 1000 mm to 1600 mm.

[0016] Exemplarily, in the fiber fabric weaving process, the loom speed is 20 to 50 picks per minute.

[0017] Specifically, in S2, the embryo body in the pressing mold is heated by one or more heating methods such as infrared heating, contact heating, resonance heating, etc.; the pressing method is performed by a hydraulic press.

[0018] Preferably, the heating temperature in S2 is 180-220° C., the pressing pressure is 200-400T, and the pressing time is 20-30 min.

[0019] Furthermore, the injection molding process comprises the following steps:

[0020] S4-1, placing the preform cut in S3 into a forming mold and performing vacuum treatment;

[0021] S4-2, glue injection under pressure, during which the pressure in the forming mold is maintained at 1000T to 3000T;

[0022] S4-3. Curing: After the injection of glue, the temperature of the forming mold is maintained at 110°C to 120°C. After 10 to 15 minutes, the forming mold is opened and the pressed semi-finished product is taken out, which is the composite material leaf spring semi-finished product.

[0023] Specifically, in S4-2, the injection pressure is 18 MPa to 20 MPa, and the injection speed is 100 g / s to 300 g / s.

[0024] Furthermore, the forming method further comprises the following steps:

[0025] S5, post-processing cutting: put the semi-finished composite leaf spring into the cutting tool and cut it according to the finished leaf spring size;

[0026] S6. Online testing: Place the finished leaf spring into the testing station for online testing.

[0027] On the other hand, an embodiment of the present invention further provides a composite leaf spring, comprising a fiber reinforcement and a resin matrix, wherein the fiber reinforcement is a three-dimensional fiber fabric with 20 to 100 layers, and the resin matrix is ​​wrapped around the outside of the three-dimensional fiber fabric and penetrated into the fibers of the three-dimensional fiber fabric;

[0028] The resin matrix is ​​infiltrated and combined with the three-dimensional fiber fabric by a high-pressure glue injection method, and the three-dimensional fiber fabric is pre-pressed and formed before the high-pressure glue injection;

[0029] The vertical fatigue times of the composite material leaf spring is 30W to 40W times.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] 1. The composite leaf spring forming system of the present invention includes a fiber cloth weaving system, a preformed body heating and pre-pressing forming system, a preformed body cutting system, a high-pressure glue injection system, and post-processing, etc. The composite material of the required thickness provided by the fiber cloth weaving system is cut into a body by the cutting system, and then the body is preliminarily shaped into a preformed body with an arc appearance by the preformed body heating and pre-pressing forming system, and then the preformed body cutting system cuts the preformed body into preformed bodies of a specified width, and the high-pressure glue injection system continuously injects high pressure glue and solidifies to obtain a semi-finished leaf spring. The composite leaf spring forming system of the present invention realizes an efficient and low-cost manufacturing process from raw materials to finished products through the matching and coordination of various systems, and realizes the automation and continuous operation of composite leaf spring forming.

[0032] 2. The fiber cloth weaving system of the present invention continuously weaves and cuts the composite multi-layer fiber cloth into embryos, which reduces manual intervention and improves material utilization and production efficiency; the embryo heating pre-pressing forming system ensures the consistency and quality of the product by automatically controlling the temperature and pressure; the preformed embryo cutting system accurately cuts, improves cutting accuracy and efficiency, and reduces material waste; the high-pressure glue injection system uniformly injects the adhesive into the preformed body and solidifies it by continuous high-pressure glue injection, which speeds up the forming speed and improves production efficiency; finally, the post-processing and online detection system processes and detects the semi-finished leaf springs, ensuring the stability and reliability of the product, while improving the overall efficiency of production. The coordinated work of these subsystems takes into account performance, efficiency and cost, making the present invention show obvious excellence in the production of composite leaf springs.

[0033] 3. The pressing mold and cooling mold of the embryo body heating pre-pressing forming system of the present invention can process multiple embryo bodies at the same time to obtain multiple pre-formed bodies, so that the output of the pre-pressing forming stage can meet the needs of the high-pressure injection molding system, that is, the production time of a single leaf spring in the pre-pressing forming stage and the high-pressure injection molding stage can match, ensuring that the output of the pre-pressing forming stage can continuously supply the high-pressure injection molding system, effectively shortening the assembly line production cycle and improving production efficiency.

[0034] 4. The present invention adopts a fiber weaving method to directly obtain a composite material of a desired thickness. Compared with the techniques of unidirectional fiber cloth prepreg laying and multi-layer fiber cloth sewing, the woven fibers have enhanced mechanical properties in the Z-axis direction, further enhancing the mechanical properties of the leaf spring of the composite material, especially significantly improving the interlayer bonding strength and fatigue performance of the composite leaf spring.

[0035] 5. Compared with the prior art, the composite leaf spring obtained by the present invention has the characteristics of better interlayer bonding strength and better fatigue performance.

[0036] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0038] Figure 1 It is a process roadmap of the composite leaf spring forming method of the present invention;

[0039] Figure 2 This is a diagram of the composite leaf spring forming system of the present invention;

[0040] Figure 3 It is a plan layout diagram of the composite leaf spring forming system of the present invention;

[0041] Figure 4 It is a loom diagram of the present invention;

[0042] Figure 5 The embryo body heating pre-pressing forming system of the present invention;

[0043] Figure 6 This is a diagram of the preformed embryo cutting system of the present invention;

[0044] Figure 7 The high-pressure glue injection system of the present invention;

[0045] Figure 8 The post-processing system of the present invention;

[0046] Fig. 9 This is the online detection system of the present invention.

[0047] Reference numerals:

[0048] 1-Fiber cloth weaving system; 2-Embedment heating and pre-pressing forming system; 3-Preformed embryo cutting system; 4-High-pressure glue injection system; 5-Post-processing and online detection system; 6-Manipulator. DETAILED DESCRIPTION

[0049] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0050] In one aspect, a specific embodiment of the present invention discloses a composite leaf spring forming system, such as Figure 2 , Figure 3 As shown, it includes multiple subsystems that operate continuously: a fiber cloth weaving system 1, a preform heating and pre-pressing forming system 2, a preformed preform cutting system 3, a high-pressure glue injection system 4, and a post-processing and online detection system 5, which are sequentially transmitted by a robot 6;

[0051] The fiber cloth weaving system 1 comprises a loom and a cutting system arranged at the loom outlet, such as Figure 4 As shown, the cutting system cuts the composite multi-layer fiber cloth with a width of not less than 1000 mm continuously woven by the loom into embryonic bodies;

[0052] like Figure 5 As shown, the embryo heating pre-pressing forming system 2 includes a pressing mold and a cooling mold, which are used to preliminarily shape the embryo continuously conveyed by the robot 6 to form a preformed embryo with an arc appearance;

[0053] like Figure 6 As shown, the preformed embryo cutting system 3 cuts the preformed embryo into preforms of a specified width;

[0054] like Figure 7 As shown, the high-pressure glue injection system 4 includes a forming mold and a glue injection system, and the adhesive is uniformly injected into the preformed body by continuous high-pressure glue injection, and a leaf spring semi-finished product is obtained after curing;

[0055] like Figure 8 , Fig. 9 As shown, the semi-finished leaf spring product is sent to the post-processing and online detection system 5 for processing and detection by the robot 6, and the qualified leaf spring product is sent out of the forming system by the robot.

[0056] The forming system of the present invention adopts a continuous operation mode, integrating multiple processes such as fiber cloth weaving, blank heating and pre-pressing forming, cutting, high-pressure glue injection, post-processing and online detection. Compared with the existing segmented production method of composite leaf springs, the integrated design greatly simplifies the production process, reduces intermediate links and material handling, and improves production efficiency and consistency of product quality; the forming system includes a post-processing and online detection system, which can perform real-time size detection and stiffness detection on leaf spring products, which helps to timely discover defects and deviations in the production process, ensure that product quality meets standard requirements, and improve the product qualification rate and reliability.

[0057] The fiber cloth weaving system 1 cuts the composite multi-layer fiber cloth continuously woven by the loom into embryos, and then transfers the embryos to the embryo heating pre-pressing forming system 2 through the manipulator 6; in the pre-pressing forming system 2, the pressing mold and the cooling mold perform preliminary shaping on the embryo to form a pre-formed embryo with an arc appearance; the pre-formed embryo is sent to the pre-formed embryo cutting system 3 by the manipulator, and the pre-formed embryo is cut into pre-formed bodies of a specified width to prepare for the subsequent high-pressure injection process; the cut pre-formed body is transferred to the high-pressure injection system 4 through the manipulator 6, and the forming mold and the injection system uniformly inject the adhesive into the pre-formed body by continuous high-pressure injection, and a semi-finished leaf spring is obtained after curing; after the semi-finished leaf spring comes out of the high-pressure injection system, it is sent to the post-processing and online detection system 5 through the manipulator 6; in the post-processing system, operations such as grinding flash, cutting ends and positioning surfaces are performed to meet the appearance and size requirements of the product, and the online detection system performs size detection and stiffness detection on the leaf spring to ensure that the product quality is qualified.

[0058] In a possible design, the loom is a three-dimensional loom controlled by a multi-axis servo control system, which controls the coordinated movement of each moving part according to a set program to achieve high-speed weaving of multi-layer three-dimensional fabrics.

[0059] The cutting system at the loom outlet and the preformed embryo cutting system are both ultrasonic cutting, including an ultrasonic generator, a transducer, an amplitude transformer and a cutting tool. The ultrasonic generator converts electrical energy into high-frequency electrical signals and controls the amplitude. The transducer converts the electrical signal into mechanical vibration. The amplitude transformer adjusts and amplifies the vibration energy, controls the amplitude and cutting force of the cutting tool, cuts the composite multi-layer fiber cloth into embryos or cuts the preformed embryos into preforms of specified width, providing precise, efficient and heat-free cutting effects.

[0060] The molding die includes an upper die, a lower die, a vacuum system, a sealing structure, a temperature control system and a pressure control system. The upper die and the lower die form a cavity. The injection system is installed on the upper part of the molding die. When in use, the preform is placed in the cavity. After the upper and lower dies are closed and locked, the pressure is increased to a certain pressure through the pressure control system. The cavity is vacuumed by the vacuum system. According to the set injection flow rate and injection time, the injection system performs resin injection at a certain injection pressure. After completion, pressure maintenance and curing are performed. After pressure maintenance and curing, pressure relief, vacuum breaking, and ejector demolding are performed in sequence to obtain a composite leaf spring semi-finished product.

[0061] It should be noted that the high-pressure injection system 4 adopts a high-pressure resin transfer molding process. The HP-RTM (high-pressure resin transfer molding) process has fast mold filling and good infiltration effect, and the injection and curing of the resin are completed in one step. The production cycle is short (≤15min), the process stability and repeatability are high, and it can be applied to a continuous operation system to achieve low-cost, short-cycle (large-volume) and high-quality production.

[0062] It is worth noting that the pressing mold and cooling mold of the embryo heating pre-pressing forming system 2 can process multiple embryos at the same time to obtain multiple preforms, so that the output of the pre-pressing forming stage can meet the needs of the high-pressure injection system, that is, the production time of a single leaf spring in the pre-pressing forming stage and the high-pressure injection forming stage can match, ensuring that the output of the pre-pressing forming stage can continuously supply the high-pressure injection system. Effectively shorten the production cycle of the assembly line and improve production efficiency.

[0063] In a possible design, the pressing mold and cooling mold of the pre-pressing forming system can process 16 embryos at the same time, that is, 16 leaf spring preforms are produced at the same time in 80 minutes, and the forming time of a single leaf spring preform is 5 minutes; in the high-pressure injection system, the forming mold can produce 4 leaf springs per mold, and the forming cycle of each mold is 20 minutes, so the forming cycle of a single leaf spring is also 5 minutes. The processing cycles of the pre-pressing forming system and the high-pressure injection system are matched with each other. Preferably, the pressing mold and cooling mold in the pre-pressing forming system can be equipped with multiple units to process embryos at the same time for use in the subsequent forming process.

[0064] Specifically, the post-processing is performed in a cutting tool, including grinding burrs, cutting ends and positioning surfaces, and the online detection includes size detection and rigidity detection.

[0065] On the other hand, a specific embodiment of the present invention also discloses a composite leaf spring forming method, such as Figure 1 As shown, it includes preform preparation and injection molding, and the preform preparation includes the following steps:

[0066] S1. Weaving of fiber cloth: putting fiber filaments into spindles and installing them on a yarn frame to weave a fiber fabric with 20 to 100 composite layers, and cutting to obtain an embryo with a thickness of 20-80 mm;

[0067] S2, embryo pre-pressing: the embryo of S1 is placed in a pressing mold by a robot to heat it and press it into a pre-formed embryo with a certain curvature. After the pressing is completed, the pre-formed embryo is transferred to a cooling mold to cool and shape it;

[0068] S3. Preform cutting: According to the outer dimensions of the leaf spring product, the preform is cut into preforms of specified width. The cut preforms are transferred to the high-pressure injection system by a robot.

[0069] Preferably, the fiber filaments in S1 include one or more of glass fiber, carbon fiber, basalt fiber, aramid fiber, and plant fiber.

[0070] Preferably, the loom speed in the weaving process in S1 is 20 to 50 picks / minute, and the weaving efficiency is high. The loom speed is 20, 30, 40, 50 picks / minute.

[0071] The composite number and thickness of the fiber fabric meet the requirements, providing a high-quality preform for subsequent injection molding, thereby improving the performance and durability of the final product; by selecting different types and proportions of fiber filaments, it can be optimized according to the product's performance requirements and cost budget to achieve the best balance between performance and cost.

[0072] In one possible design, the fiber filaments used in the weaving of the fiber cloth are 50% carbon fiber + 50% glass fiber, which has a lower price while meeting the performance requirements;

[0073] In one possible design, the fiber filaments used for weaving the fiber cloth are 70% carbon fiber + 30% basalt fiber, which has better impact resistance;

[0074] In one possible design, the fiber filaments used in weaving the fiber cloth are 60% carbon fiber + 40% plant fiber, and the product better meets environmental protection performance requirements.

[0075] Specifically, the weaving method of the fiber cloth in S1 is one or more of single-layer weaving, warp and weft weaving, 2.5D weaving, and 3D weaving.

[0076] Exemplarily, the fiber fabric in S1 has a width of 1000 mm to 1600 mm. Preferably, the fiber fabric has 20 layers, 30 layers, 40 layers, 50 layers, 60 layers, or 100 layers.

[0077] The number of layers of the fiber fabric is designed according to the thickness of the leaf spring product, wherein the thickness of a single layer is 0.6 mm; the width of the fiber fabric is determined according to the leaf spring product. For example, when the width of the fiber fabric is 1600 mm, 8 leaf spring preforms with a width of 200 mm can be produced simultaneously, thereby improving production efficiency.

[0078] It should be noted that the method of heating the embryo body in the pressing mold in S2 is one or more of the heating methods such as infrared heating, contact heating, resonance heating, etc.; the pressing method is carried out using a hydraulic press.

[0079] Preferably, in S2, the heating temperature is 180-220°C, the pressing pressure is 200-400T, and the pressing time is 20-30min. The heating temperature is 180, 190, 210, 220°C, and the pressing pressure is 200, 300, 400T.

[0080] It is worth noting that before heating the embryo in S2, the shaping powder is evenly sprinkled on the embryo surface. The shaping powder is a thermoplastic resin, which is at least one of polypropylene resin, polyamide resin, polyester resin, polyphenylene ether resin, and polystyrene, and the amount is 8-12g / m 2 After heating, the powder becomes liquid, bonding the loose fibers between different layers together. After cooling, the powder becomes solid again, allowing the fibers to maintain a certain curved shape.

[0081] The embryo body is pre-pressed to give it a preliminary curved appearance. Pre-pressing can shorten the cycle of subsequent injection molding. Pre-pressing can also reduce the difficulty of resin injection filling and speed up the production process.

[0082] Preferably, in S2, the preformed embryo is cooled in a cooling mold to a temperature below 50° C. to complete shaping, and the cooling method is one or more cooling methods such as mold cooling or air cooling.

[0083] In one possible design, the cooling method in S2 is mold cooling, and the mold temperature is 50°C;

[0084] In a possible design, the cooling method in S2 is mold cooling, and the mold temperature is 30°C.

[0085] Rapid and uniform cooling helps reduce internal stress and deformation of the preform during cooling, thereby improving the dimensional stability and physical and mechanical properties of the final product.

[0086] Specifically, the preformed embryo body cutting in S3 is performed by one or more of vibration cutting, laser cutting, ultrasonic cutting and high-pressure water cutting.

[0087] In a possible design, the preformed embryo is cut by ultrasonic cutting. The ultrasonic cutting system can provide accurate, efficient and heat-damaging cutting effects to achieve precision machining.

[0088] Furthermore, the injection molding process comprises the following steps:

[0089] S4-1, the robot puts the preform cut by S3 into the forming mold, and then performs vacuum treatment;

[0090] S4-2, glue injection under pressure, during which the pressure in the forming mold is maintained at 1000T to 3000T;

[0091] S4-3. Curing: After injection of glue, the temperature of the forming mold is maintained at 110℃~120℃. After 10~15 minutes, the forming mold is opened, and the pressed semi-finished product, i.e. the composite leaf spring semi-finished product, is taken out and sent to the post-processing system through a robot.

[0092] The cut preform is placed in a forming mold and vacuumed to ensure that the air inside the mold is completely extracted to avoid bubbles during the injection process, thereby improving the density and quality of the product. The vacuum environment helps the resin to penetrate better and improve the interface bonding ability between the fiber and the resin, thereby improving the quality of the product. The preform is injected under high pressure in the forming mold to ensure that the resin quickly fills the mold cavity under the action of high pressure. High-pressure injection helps the resin flow and fill the mold, and these processes can be completed in a shorter time, shortening the production cycle. Finally, in the curing process, appropriate curing temperature and time can ensure that the resin is fully cured to form a composite leaf spring semi-finished product with certain strength and stiffness.

[0093] Specifically, the vacuum degree of the mold in S4-1 reaches -0.08MPa to -0.1MPa.

[0094] Preferably, the injection pressure in S4-2 is 18MPa-20MPa, and the injection speed is 100g / s-300g / s. Preferably, the pressure in the forming mold is maintained at 1000T, 1500T, 2000T, 2500T, 3000T, the injection pressure is 18MPa, 19MPa, 20MPa, and the injection speed is 100g / s, 120g / s, 140g / s, 150g / s, 170g / s, 180g / s, 200g / s, 220g / s, 240g / s, 250g / s, 270g / s, 280g / s, 300g / s.

[0095] Preferably, during the S4-3 curing process, the temperature of the forming mold is maintained at 110°C, 115°C, or 120°C, and the curing time is 10, 11, 12, 13, 14, or 15 minutes.

[0096] Due to the relatively thick preform thickness of 20 to 80 mm, the injection molding process requires a large amount of injection. In order to ensure that the resin can fully penetrate into each layer of the material and effectively eliminate bubbles, process parameters such as the pressure in the molding mold and the injection pressure need to be precisely controlled according to the thickness of the preform to achieve efficient and uniform resin distribution, thereby producing composite products with stable structure and excellent performance.

[0097] Preferably, the injection composition includes epoxy resin, curing agent and release agent, wherein the mass ratio of epoxy resin to curing agent is 100:20, and the amount of release agent is 0.5% of the mass fraction of epoxy resin.

[0098] Furthermore, the forming method further comprises the following steps:

[0099] S5, post-processing cutting: the semi-finished composite leaf spring brought by the robot is cut into the finished leaf spring size in the cutting tool, and then the robot transfers it to the online detection system after completion;

[0100] S6. Online inspection: Put the finished leaf spring into the inspection station for online inspection. The qualified finished product will be sent out of the forming system by the robot.

[0101] Preferably, the finished leaf spring obtained in S5 has a thickness of 30-90 mm.

[0102] Specifically, the online inspection described in S6 includes one or more of appearance inspection, non-destructive inspection, stiffness inspection, performance inspection, etc.

[0103] The present invention achieves improvement in the mechanical properties and structural optimization of the composite leaf spring by optimizing the number of layers of the composite multi-layer fiber cloth and the ratio of the fiber filaments. The composite leaf spring exhibits lower damage accumulation and better fatigue resistance under cyclic stress, which significantly improves its reliability and durability in actual use.

[0104] The present invention sets a pre-pressing process for the embryo before HP-RTM forming, and accurately controls process parameters such as the pre-pressing temperature and pressure. On the one hand, the pre-pressing process can reduce the difficulty of resin injection filling, complete the finalization of some shapes in advance, help reduce the waiting and adjustment time in the HP-RTM process, and improve the overall efficiency of the production line; on the other hand, the pre-pressing process helps to fix the shape of the product before curing, reduces deformation in subsequent processing, and improves the dimensional stability and consistency of the product; controlling appropriate temperature and pressure helps to fully combine the resin and the fiber, and improves the mechanical properties of the composite material.

[0105] According to the structural characteristics of the composite multi-layer fiber cloth, the present invention accurately controls the pressing pressure, injection pressure and injection speed to achieve uniform impregnation and optimized molding of the composite material leaf spring. By accurately adjusting these parameters, it is ensured that each layer of the composite multi-layer fiber cloth can be fully combined with the adhesive, thereby enhancing the interlayer bonding strength and improving the overall performance of the leaf spring.

[0106] On the other hand, a specific embodiment of the present invention further provides a composite leaf spring, comprising a fiber reinforcement and a resin matrix, wherein the fiber reinforcement is a three-dimensional fiber fabric with 20 to 100 layers, and the resin matrix is ​​wrapped around the outside of the three-dimensional fiber fabric and penetrated into the fibers of the three-dimensional fiber fabric;

[0107] The resin matrix is ​​infiltrated and combined with the three-dimensional fiber fabric by a high-pressure glue injection method, and the three-dimensional fiber fabric is pre-pressed and formed before the high-pressure glue injection;

[0108] The vertical fatigue times of the composite material leaf spring is 30W to 40W times.

[0109] In summary, the composite leaf spring forming system of the present invention realizes an efficient and low-cost manufacturing process from raw materials to finished products by integrating multiple automated and continuously operating subsystems; the coordinated work of these subsystems takes into account performance, efficiency and cost, so that the present invention shows obvious excellence in the production of composite leaf springs; the present invention adopts a fiber weaving method to directly obtain a composite material of the required thickness, and the mechanical properties of the woven fibers are enhanced in the Z-axis direction, further enhancing the mechanical properties of the leaf spring of the composite material, especially the interlayer bonding strength of the composite leaf spring, and the fatigue performance is significantly improved, with the vertical fatigue number of 30W to 40W times.

[0110] The composite material leaf spring forming method of the present invention is described below with reference to specific embodiments.

[0111] Example 1

[0112] This embodiment provides a forming system for a composite leaf spring.

[0113] It includes multiple subsystems that operate continuously: a fiber cloth weaving system 1, a preform heating and pre-pressing forming system 2, a preform cutting system 3, a high-pressure glue injection system 4, and a post-processing and online detection system 5, which are sequentially transmitted through a robot 6;

[0114] The fiber cloth weaving system 1 comprises a loom and a cutting system arranged at the loom outlet, wherein the cutting system cuts the composite multi-layer fiber cloth with a width of not less than 1000 mm continuously woven by the loom into embryonic bodies;

[0115] The embryo heating pre-pressing forming system 2 includes a pressing mold and a cooling mold, which are used to preliminarily shape the embryo continuously conveyed by the robot 6 to form a preformed embryo with an arc appearance;

[0116] The preformed body cutting system 3 cuts the preformed body into preforms of a specified width;

[0117] The high-pressure glue injection system 4 includes a forming mold and a glue injection system, and the adhesive is uniformly injected into the preformed body by continuous high-pressure glue injection, and a semi-finished leaf spring is obtained after curing;

[0118] The semi-finished leaf spring products are sent to the post-processing and online testing system 6 for processing and testing by the robot 5, and qualified leaf spring products are sent out of the forming system by the robot.

[0119] When the forming system is in use: the fiber cloth weaving system 1 cuts the composite multi-layer fiber cloth continuously woven by the loom into embryos, and then transfers the embryos to the embryo heating pre-pressing forming system 2 through the manipulator 6; in the pre-pressing forming system, the pressing mold and the cooling mold perform preliminary shaping on the embryo to form a pre-formed embryo with an arc appearance; the pre-formed embryo is sent to the pre-formed embryo cutting system 3 by the manipulator 6, and the pre-formed embryo is cut into pre-formed bodies of a specified width to prepare for the subsequent high-pressure injection process; the cut pre-formed body is transferred to the high-pressure injection system 4 through the manipulator 6, and the forming mold and the injection system uniformly inject the adhesive into the pre-formed body by continuous high-pressure injection, and a semi-finished leaf spring is obtained after curing; after the semi-finished leaf spring comes out of the high-pressure injection system, it is sent to the post-processing and online detection system 5 through the manipulator 6; in the post-processing system, operations such as grinding flash, cutting ends and positioning surfaces are performed to meet the appearance and size requirements of the product, and the online detection system performs size detection and stiffness detection on the leaf spring to ensure that the product quality is qualified.

[0120] Example 2

[0121] This embodiment provides a forming system and a forming method for a composite leaf spring.

[0122] The composite leaf spring forming system provided in Example 1 is used to manufacture the composite leaf spring.

[0123] The production of a heavy-duty front spring with a braid width of 100 mm and a thickness of 80 mm, using a fiber yarn of 50% carbon fiber + 50% glass fiber, includes the following steps:

[0124] S1. Weaving of fiber cloth: Put the fiber filaments with the required number of strands into the spindle and install them on the creel. According to the weaving setting, a weaving speed of 30 picks / minute is adopted for high-speed weaving. The width of the woven fabric is 1000 mm, the weaving length is 1500 mm, the number of layers of the fiber woven fabric is 100, and the thickness is 80 mm.

[0125] S2, embryo body heating pre-pressing forming: put the woven fiber fabric into a pressing mold, the mold temperature is 200°C, and the woven fabric is pressed into a preform with a certain curvature by a hydraulic press, the pressing pressure is 300T, the pressing time is 30min, and after the pressing is completed, it is transferred to a cooling mold for cooling and shaping, the cooling mold temperature is 50°C, and the cooling time is 50min;

[0126] S3. Preformed body cutting: according to the outer dimensions of the leaf spring product, ultrasonic cutting is adopted, and the cutting knife frequency is set to 100HZ to cut the preformed body into a preformed body with a width of 100mm that is consistent with the outer shape of the leaf spring and of a specified width;

[0127] S4, injection molding: put the cut preform into the molding die, and evacuate the mold into a vacuum state after 60 seconds, and the pressure gauge shows -0.08MPa;

[0128] The mold was pressurized to 2000T, and epoxy resin was rapidly injected into the mold at a flow rate of 200g / s under 19MPa;

[0129] After the injection is completed, the mold is kept at 110°C for 10 minutes for curing, and then the mold is opened to take out the pressed leaf spring semi-finished product;

[0130] The injection glue composition includes epoxy resin, curing agent and release agent, wherein the mass ratio of epoxy resin to curing agent is 100:20, and the amount of release agent is 0.5% of the mass fraction of epoxy resin.

[0131] S5, post-processing cutting: After placing the semi-finished leaf spring into the cutting tool, the leaf spring is deburred, punched and trimmed using a five-axis machining center at a speed of 10m / min;

[0132] S6. Online inspection: Place the processed composite leaf spring product into the inspection station for online inspection. Use visual inspection to inspect the appearance of the leaf spring, and use specific tooling to inspect the compressive stiffness and fatigue performance of the leaf spring.

[0133] The fatigue performance test results of leaf spring finished products are shown in Table 1.

[0134] Example 3

[0135] This embodiment provides a forming system and a forming method for a composite leaf spring.

[0136] The composite leaf spring forming system provided in Example 1 is used to manufacture the composite leaf spring.

[0137] The main spring of a rear spring of a composite material commercial vehicle with a weaving width of 70 mm and a thickness of 80 mm is produced by using 70% carbon fiber + 30% basalt fiber, including the following steps:

[0138] S1. Weaving of fiber cloth: Put the fiber filaments with the required number of strands into the spindle and install them on the creel. According to the weaving setting, a weaving speed of 40 picks / minute is adopted for high-speed weaving. The width of the woven fabric is 1400 mm, the weaving length is 1900 mm, the number of layers of the fiber braid is 100, and the thickness is 80 mm.

[0139] S2. Pre-pressing the embryo body by heating: Put the woven fiber fabric into a pressing mold with a mold temperature of 190°C, and use a hydraulic press to press the woven fabric into a preform with a certain curvature. The pressing pressure is 200T and the pressing time is 30min. After the pressing is completed, transfer it to a cooling mold for cooling and shaping. The cooling mold is 30°C and the cooling time is 60min.

[0140] S3. Preformed body cutting: according to the outer dimensions of the leaf spring product, ultrasonic cutting is adopted, and the cutting knife frequency is set to 100HZ to cut the preformed body into a preformed body with a width of 70mm that is consistent with the outer shape of the leaf spring with a specified width;

[0141] S4, injection molding: put the cut preform into the molding die, and evacuate the mold into a vacuum state after 120 seconds, and the pressure gauge shows -0.1MPa;

[0142] The mold was pressurized to 3000T, and epoxy resin was rapidly injected into the mold at a flow rate of 300g / s at 20MPa;

[0143] After the injection is completed, the mold is kept at 110°C for 15 minutes for curing, and then the mold is opened to take out the pressed leaf spring semi-finished product;

[0144] The injection glue composition includes epoxy resin, curing agent and release agent, wherein the mass ratio of epoxy resin to curing agent is 100:20, and the amount of release agent is 0.5% of the mass fraction of epoxy resin.

[0145] S5, post-processing cutting: After placing the semi-finished leaf spring into the cutting tool, the leaf spring is subjected to flash removal, punching and trimming operations at a speed of 5m / min by water jet cutting;

[0146] S6. Online inspection: Place the processed composite leaf spring product into the inspection station for online inspection. Use visual inspection to inspect the appearance of the leaf spring, and use specific tooling to inspect the compressive stiffness and fatigue performance of the leaf spring.

[0147] The fatigue performance test results of leaf spring finished products are shown in Table 1.

[0148] Example 4

[0149] This embodiment provides a forming system and a forming method for a composite leaf spring.

[0150] The composite leaf spring forming system provided in Example 1 is used to manufacture the composite leaf spring.

[0151] The leaf spring dimensions are the same as those of Example 2, and the forming steps are substantially the same as those of Example 2, except that a single type of glass fiber yarn is used.

[0152] The fatigue performance test results of leaf spring finished products are shown in Table 1.

[0153] Comparative Example 1

[0154] This comparative example provides a method for forming a composite leaf spring.

[0155] The unidirectional fiber cloth prepreg layer is used to mold the 70mm wide and 60mm thick composite leaf spring. The specific process is as follows:

[0156] (1) Prepreg cutting: cutting the prepreg into single-layer prepregs with a width of 70 mm;

[0157] (2) Prepreg layering: repeatedly stack single layers of 0.4 mm prepreg, stacking 175 layers to a total thickness of 70 mm;

[0158] (3) Pressing in a press, using different temperature rise programs for the mold according to the curing curve of the prepreg to ensure that the leaf spring is completely cured;

[0159] The main process parameters of pressing are: press pressure 800T, temperature curve is 80℃ for 30min, then heating to 120℃ for 60min, cooling to 70℃ for 30min.

[0160] (4) Product post-processing: take out the formed leaf spring, perform trimming and punching to obtain the product.

[0161] The fatigue performance test results of leaf spring finished products are shown in Table 1.

[0162] Comparative Example 2

[0163] This comparative example provides a method for forming a composite leaf spring.

[0164] The size of the leaf spring is the same as that of Example 2, and the types, proportions and forming steps of the fiber filaments are basically the same as those of Example 2, except that the number of fiber fabric layers in step S1 is 15.

[0165] The fatigue performance test results of leaf spring finished products are shown in Table 1.

[0166] Comparative Example 3

[0167] This comparative example provides a method for forming a composite leaf spring.

[0168] The size of the leaf spring is the same as that of Example 2, and the forming steps are basically the same as those of Example 2, except that in step S4, the mold is pressurized to 900T and the epoxy resin injection pressure is 15MPa.

[0169] The fatigue performance test results of leaf spring finished products are shown in Table 1.

[0170] Table 1 Fatigue performance test results of leaf springs of embodiments and comparative examples

[0171] project Single piece production cycle Forming efficiency Vertical fatigue times Example 2 15min high 40W times Example 3 20min high 40W times Example 4 15min high 30W times Comparative Example 1 120min Low 100,000 times Comparative Example 2 15min high 150,000 times Comparative Example 3 15min high 25W times

[0172] Example 1 provides a composite leaf spring forming system with efficient connection between various processes and continuous operation. Example 2, Example 3 and Example 4 use the composite leaf spring forming system and forming method provided in Example 1 to prepare composite leaf springs, thereby achieving a short production cycle for a single leaf spring, high forming efficiency and good mechanical properties.

[0173] It can be seen from the single leaf spring production cycle in Table 1 that the comparative example 1 adopts the resin prepreg layering method to prepare the composite leaf spring, and the forming efficiency is much lower than that of Examples 2 to 4 prepared by the composite leaf spring forming system of the present invention.

[0174] It can be seen from the vertical fatigue times in Table 1 that, compared with Examples 2 and 3, Example 4 has slightly worse fatigue performance due to the use of a single glass fiber yarn with slightly inferior mechanical properties for weaving the fiber cloth; Comparative Example 1 adopts a resin prepreg layering method to prepare a composite leaf spring, and compared with Examples 2 to 4, the fatigue performance is poor; Compared with Example 2, Comparative Example 2 has poor fatigue performance of the composite leaf spring due to the number of fiber cloth layers not meeting the requirements of the present invention; Compared with Example 2, the mold pressure and injection pressure during the high-pressure injection process of Comparative Example 3 do not meet the requirements of the present invention, and do not match the thickness and performance of the composite multi-layer fiber cloth of the present invention, resulting in poor fatigue performance of the leaf spring.

[0175] The fatigue life of a composite leaf spring under repeated loading can indirectly reflect the stability of interlayer bonding. Good interlayer bonding means a higher fatigue life. By comparing Example 1 with Example 2, the fatigue performance of a composite leaf spring prepared by the resin prepreg lamination method is much lower than that of a leaf spring prepared by the fiber weaving method to directly obtain a composite material of the desired thickness. This indicates that the interlayer bonding strength of the composite leaf spring of the present invention is significantly improved compared with the prior art.

[0176] In summary, the composite leaf spring forming system of the present invention realizes an efficient and low-cost manufacturing process from raw materials to finished products by integrating multiple automated and continuously operating subsystems; the coordinated work of these subsystems takes into account performance, efficiency and cost, so that the present invention shows obvious excellence in the production of composite leaf springs; the present invention adopts a fiber weaving method to directly obtain a composite material of the required thickness, and the woven fibers have enhanced mechanical properties in the Z-axis direction, further enhancing the mechanical properties of the leaf spring of the composite material, especially significantly improving the interlayer bonding strength and fatigue performance of the composite leaf spring.

[0177] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A composite leaf spring forming system, characterized in that: It includes multiple subsystems that operate continuously: fiber cloth weaving system, embryo heating and pre-pressing system, pre-formed embryo cutting system, high-pressure glue injection system, post-processing and online detection system, which are sequentially transferred by the robot. The fiber cloth weaving system includes a loom and a cutting system arranged at the loom outlet, and the cutting system cuts the composite multi-layer fiber cloth with a width of not less than 1000 mm continuously woven by the loom into embryonic bodies; The embryo body heating pre-pressing forming system comprises a pressing mold and a cooling mold, which are used to preliminarily shape the embryo body continuously conveyed by the robot arm to form a preformed embryo body with an arc appearance; The preformed embryo cutting system cuts the preformed embryo into preforms of a specified width; The high-pressure glue injection system includes a forming mold and a glue injection system, and the adhesive is uniformly injected into the preformed body by continuous high-pressure glue injection, and a leaf spring semi-finished product is obtained after curing; The semi-finished leaf spring products are sent to the post-processing and online detection system for processing and detection by the robot, and the qualified leaf spring products are sent out of the forming system by the robot.

2. A composite leaf spring forming method, characterized in that: The method comprises preform preparation and injection molding, wherein the preform preparation comprises the following steps: S1. Weaving of fiber cloth: putting fiber filaments into spindles and installing them on a yarn frame to weave a fiber fabric with 20 to 100 composite layers, and cutting to obtain an embryo with a thickness of 20-80 mm; S2, embryo pre-pressing: the embryo of S1 is placed in a pressing mold, heated, and pressed into a pre-formed embryo with a certain curvature. After the pressing is completed, the pre-formed embryo is transferred to a cooling mold to cool and shape; S3. Preform blank cutting: according to the outer dimensions of the leaf spring product, the preform is cut into preforms of specified width.

3. The forming method according to claim 2, characterized in that: The fiber filaments described in S1 include one or more of glass fiber, carbon fiber, basalt fiber, aramid fiber, and plant fiber.

4. The forming method according to claim 2, characterized in that: The fiber fabric described in S1 has a width of 1000 mm to 1600 mm; during the weaving process of the fiber fabric, the loom speed is 20 to 50 picks per minute.

5. The forming method according to claim 2, characterized in that: In S2, the embryo body in the pressing mold is heated by one or more heating methods such as infrared heating, contact heating, resonance heating, etc.; the pressing method is performed by a hydraulic press.

6. The forming method according to claim 5, characterized in that: In S2, the heating temperature is 180-220°C, the pressing pressure is 200-400T, and the pressing time is 20-30min.

7. The forming method according to claim 2, characterized in that: The injection molding process comprises the following steps: S4-1, placing the preform cut in S3 into a forming mold and performing vacuum treatment; S4-2, glue injection under pressure, during which the pressure in the forming mold is maintained at 1000T to 3000T; S4-3. Curing: After the injection of glue, the temperature of the forming mold is maintained at 110°C to 120°C. After 10 to 15 minutes, the forming mold is opened and the pressed semi-finished product is taken out, which is the composite material leaf spring semi-finished product.

8. The forming method according to claim 7, characterized in that: In S4-2, the injection pressure is 18MPa~20MPa, and the injection speed is 100g / s~300g / s.

9. The forming method according to claim 8, characterized in that: The forming method further comprises the following steps: S5, post-processing cutting: put the semi-finished composite leaf spring into the cutting tool and cut it according to the finished leaf spring size; S6. Online testing: Place the finished leaf spring into the testing station for online testing.

10. A composite leaf spring, characterized in that: The composite leaf spring is prepared by the forming method according to any one of claims 2 to 9, wherein the composite leaf spring comprises a fiber reinforcement and a resin matrix, the fiber reinforcement is a three-dimensional fiber fabric with 20 to 100 layers, and the resin matrix is ​​wrapped around the outside of the three-dimensional fiber fabric and penetrated into the fibers of the three-dimensional fiber fabric; The resin matrix is ​​impregnated and combined with the three-dimensional fiber fabric pre-pressed and formed before high-pressure injection by a high-pressure injection method; The vertical fatigue times of the composite material leaf spring is 30W to 40W times.

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