A pellegrini racket panel based on PE fiber hot-press forming and a preparation method thereof

Abstract

The application discloses a pick racket panel based on PE fiber hot-press forming and a preparation method thereof, and relates to the field of sports equipment manufacturing.The panel comprises a core layer and reinforcing layers combined on the upper and lower surfaces of the core layer, the core layer is a polymer honeycomb core material or a low-density closed-cell foam, the reinforcing layers are mainly made of ultrahigh molecular weight PE fibers, and two layering schemes of balanced type and mixed type are provided.The preparation method comprises the following steps of mold preparation, layering preforming, hot-press curing, demolding and post-processing, and through a special resin system and a precise temperature control and pressurization process, firm adhesion of the layers is ensured.The application utilizes the high strength, high toughness, lightweight and excellent shock absorption characteristics of the PE fibers, solves the problems of high brittleness and poor durability of traditional rackets, realizes the synergistic optimization of strength, toughness, shock absorption and fault tolerance, and the product has stable performance, is suitable for users with different levels, and has comfortable hand feeling and long service life.

Description

Technical Field

[0001] This invention relates to the field of sports equipment manufacturing technology, specifically to a Peak racket panel based on PE fiber hot pressing molding and its preparation method. Background Technology

[0002] Peakball, a sport that combines fun and competition, has rapidly gained popularity worldwide in recent years, leading to increasing market demand for high-performance Peak rackets. Currently, most Peak racket panels on the market are made from traditional composite materials such as carbon fiber and glass fiber. While these materials possess a certain degree of rigidity, they have significant performance drawbacks: First, they are highly brittle, easily prone to edge cracking and surface peeling due to bumps and impacts during daily use, resulting in insufficient durability and a short lifespan. Second, they have poor shock absorption; the intense vibrations generated during a shot are easily transmitted to the user's arm, potentially causing muscle fatigue and even sports injuries such as tennis elbow with prolonged use. Third, they lack forgiveness; when hitting outside the sweet spot, the ball speed decreases rapidly, and the return quality is inconsistent, making them less friendly to beginners and intermediate players.

[0003] Meanwhile, the performance consistency of existing Peak racket panels is difficult to guarantee. Different batches of products exhibit fluctuations in key indicators such as strength and elasticity, failing to meet consumers' core demand for stable racket "feel." Although some manufacturers have attempted to improve performance by adjusting the layup method or adding auxiliary materials, they have failed to fundamentally solve the inherent mechanical defects of traditional composite materials, making it difficult to achieve synergistic optimization of strength, toughness, shock absorption, and fault tolerance.

[0004] Given the shortcomings of the existing technologies, there is an urgent need to develop a Peak racket panel with superior mechanical properties and a better user experience to fill the market gap for high-performance rackets and promote the technological upgrade of Peak racket equipment. Summary of the Invention

[0005] The technical problem to be solved by this invention is the high brittleness, poor shock absorption, poor fault tolerance, insufficient durability and unstable performance of existing Peak racket panels made of traditional composite materials, so as to achieve synergistic optimization of strength, toughness, shock absorption, fault tolerance and durability.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a Peak racket panel based on PE fiber hot pressing molding, comprising a core layer and a reinforcing layer, wherein the reinforcing layer is composited on the upper and lower surfaces of the core layer;

[0007] The core layer is a polymer honeycomb core material or low-density closed-cell foam, used to provide thickness, shock absorption and disperse the energy of the impact.

[0008] The main material of the reinforcing layer is ultra-high molecular weight polyethylene (PE) fiber woven fabric or unidirectional tape, and the reinforcing layer adopts one of the following two layup schemes:

[0009] Option A (Balanced Type): Only ultra-high molecular weight polyethylene fiber woven fabric is used for layup;

[0010] Option B (hybrid type): Mix and lay up ultra-high molecular weight polyethylene fiber material with a small amount of carbon fiber, with carbon fiber as the surface layer and ultra-high molecular weight polyethylene fiber material as the inner layer.

[0011] As a further aspect of the present invention: the reinforcing layer is in the form of a prepreg, wherein the prepreg is an ultra-high molecular weight polyethylene fiber material impregnated with a modified epoxy resin or thermoplastic polyurethane film, and the modified epoxy resin or thermoplastic polyurethane film has good adhesion to the ultra-high molecular weight polyethylene fiber.

[0012] A method for preparing a Peak racket panel based on PE fiber hot pressing molding includes the following steps:

[0013] (1) Mold preparation: High-precision steel molds are used. The mold cavity is a pre-set surface shape and includes wire holes. The mold surface is sprayed with a high-temperature release agent.

[0014] (2) Lay-up and preforming: Place the cut core layer material into the lower mold, and lay the reinforcing layer prepreg layer by layer on the upper and lower surfaces of the core layer according to the designed lay-up sequence;

[0015] (3) Hot pressing curing: Close the upper mold and send it into the hot press. Heat the temperature to the predetermined curing temperature of about 130°C (not exceeding the melting point of PE fiber), apply a high pressure of 10-15 atmospheres, and keep the temperature and pressure until the resin is completely cured.

[0016] (4) Demolding and post-processing: After cooling, the mold is opened and the formed panel is taken out. Then, the edges are trimmed, polished, CNC machine tool is used for precise drilling, primer is sprayed and final coating is applied.

[0017] As a further aspect of the present invention: the curing temperature in step (3) is strictly controlled below the melting point of ultra-high molecular weight polyethylene fiber to ensure that the fiber properties are not damaged.

[0018] As a further aspect of the present invention: the resin system of the reinforcing layer prepreg in step (2) is a modified epoxy resin or thermoplastic polyurethane film specifically developed for PE fibers. The resin system can fully flow, impregnate the fibers and expel air bubbles during the hot pressing process.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. Synergistic optimization of mechanical properties, balancing strength and toughness: Using ultra-high molecular weight polyethylene (PE) fiber as the core material of the reinforcing layer, combined with polymer honeycomb core material or low-density closed-cell foam core layer, the strength of PE fiber far exceeds that of traditional carbon fiber and glass fiber (15 times that of steel under the same weight) and its excellent toughness solves the pain point of high brittleness and easy breakage of traditional racket panels. At the same time, through the energy dispersion effect of the core layer, the panel maintains structural stability while having high impact resistance, and the durability and service life are greatly improved.

[0021] 2. Significant shock absorption, enhancing safety and comfort: PE fibers have a strong energy absorption capacity, which, combined with the shock absorption design of the core layer, can effectively filter the violent vibrations generated when hitting the ball, significantly reducing the risk of sports injuries such as "tennis elbow" for users; at the same time, it delivers a clear, soft and responsive hitting feel, especially in delicate operation scenarios such as net play, the feel experience far surpasses that of traditional rackets.

[0022] 3. Excellent tolerance for error, suitable for users of different skill levels: Relying on the toughness of PE fiber, the racket face can produce adaptive micro-deformation when hitting the ball outside the sweet spot, "bouncing" the ball out. This avoids the problem of rapid ball speed decay and poor return quality when hitting the ball outside the center with traditional hard material rackets, greatly improving the stability and return effect of hitting the ball outside the sweet spot. It is friendly to beginners and intermediate players, while meeting the needs of professional players for control precision.

[0023] 4. Lightweight design and high rebound characteristics: The density of PE fiber is lower than that of water, which allows the panel to be lightweight while ensuring mechanical performance, making it easy for users to swing quickly and reducing sports fatigue; through precise layering design and special resin system, the elasticity of PE fiber can be fully utilized to form a unique "trampoline effect", which increases ball speed while ensuring ball control, and achieves a balanced optimization of control and rebound performance.

[0024] 5. Stable manufacturing process and high product performance consistency: High-precision steel mold and strictly temperature-controlled hot-press curing process are adopted, combined with modified epoxy resin or thermoplastic polyurethane film that is compatible with PE fiber, to ensure that the resin fully impregnates the fiber and that each layer of structure is firmly bonded, effectively avoiding defects such as bubbles and delamination, so that the key indicators such as strength, elasticity and feel of different batches of products remain stable, meeting the needs of large-scale production and market application. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0026] Figure 1This is a flowchart illustrating a Peak racket panel based on PE fiber hot pressing and its preparation method, according to the present invention. Detailed Implementation

[0027] To make the technical solution, purpose and beneficial effects of the present invention clearer, the following detailed description of the Peak racket panel based on PE fiber hot pressing and its preparation method is provided in conjunction with specific embodiments. It should be noted that this embodiment is only used to explain the present invention and is not intended to limit the scope of protection of the present invention.

[0028] I. Raw Material Preparation

[0029] 1. Core layer material: Select material with a density of 30-50 kg / m³ 3 The polymer honeycomb core material (preferably polyvinyl chloride honeycomb core or polypropylene honeycomb core), or low-density closed-cell foam with a porosity ≥90% (such as polyether polyurethane foam), is cut into core material blanks with a length of 40-45cm, a width of 25-30cm, and a thickness of 8-12mm according to the target racket size. During the cutting process, the surface of the core material is kept flat and free from defects such as damage and dents. The edge perpendicularity error is controlled within ±0.1mm to ensure the subsequent layer adhesion.

[0030] 2. Reinforcing layer material:

[0031] Ultra-high molecular weight polyethylene (PE) fiber material: woven fabric made of ultra-high molecular weight polyethylene fibers with a molecular weight of 3-5 million (weight 150-200 g / m²). 2 The weaving density is 80-100 threads / 10cm in the warp and 80-100 threads / 10cm in the weft, or unidirectional tape (weight 200-250g / m). 2 With fiber alignment parallelism error ≤ ±1°, fiber breaking strength ≥ 30 cN / dtex, and breaking elongation 3-5%, it ensures excellent strength and toughness.

[0032] Carbon fiber material (for Option B only): T700 grade carbon fiber woven fabric with a basis weight of 180-220 g / m². 2 Tensile strength ≥4900MPa, elastic modulus ≥230GPa, used to provide initial hardness and ball speed support for the surface layer.

[0033] Resin system: Modified epoxy resin (epoxy value 0.4-0.6 eq / 100g, viscosity 500-800 mPa・s, 25℃) or thermoplastic polyurethane film (thickness 0.1-0.2mm, Shore hardness 85-90A, melting point 120-130℃) specially developed for PE fibers is used to ensure good compatibility and adhesion with PE fibers, carbon fibers and core layer materials, with an adhesion strength ≥3.5MPa (tensile shear strength, room temperature).

[0034] Prepreg preparation: The above resin system is uniformly impregnated into PE fiber woven fabric, PE fiber unidirectional tape and carbon fiber woven fabric by hot melt impregnation method. The impregnation temperature is controlled at 80-100℃ and the impregnation time is 3-5min to ensure that the fiber impregnation rate is ≥95% and the volatile content of the prepreg is ≤1.5%. It is stored in an environment of 0-5℃ for later use and the shelf life does not exceed 6 months.

[0035] 3. Auxiliary materials: High-temperature release agent (organosilicon release agent, high temperature resistance ≥200℃, film thickness 5-10μm), primer (polyurethane primer, adhesion grade ≤1, impact resistance ≥50cm), topcoat (fluorocarbon topcoat, gloss 60-80°, weather resistance ≥1000h).

[0036] II. Mold Preparation

[0037] 1. High-precision steel mold made of Cr12MoV material is used. The mold cavity is designed according to the international standard Peak racket face size (42cm long and 27cm wide). The cavity depth is set according to the total thickness of the core layer and the reinforcement layer (leaving 0.5-1mm for heat pressing shrinkage). The accuracy error of the preset position of the wire hole is ≤±0.2mm. The surface roughness of the mold cavity Ra≤0.8μm ensures that the surface of the racket face is smooth after molding.

[0038] 2. Mold pretreatment: First, clean the mold cavity and surface with acetone solution to remove oil and impurities. After air drying, use a spray gun to evenly spray high-temperature release agent at a spray pressure of 0.3-0.5MPa and a spray distance of 20-30cm to ensure that the release agent completely covers the mold surface without any omissions. Then, put the mold into an oven at 100-120℃ for 30 minutes to allow the release agent to fully form a film and prevent sticking after molding.

[0039] III. Lamination and Preforming

[0040] (a) Scheme A (Equal Type) Layup Operation

[0041] 1. Place the pretreated polymer honeycomb core material or low-density closed-cell foam core material smoothly into the center of the lower mold cavity, and fix the core material with positioning pins to ensure that the distance between the edge of the core material and the edge of the mold cavity is uniform with an error of ≤±0.3mm.

[0042] 2. Laying sequence: Starting from the top surface of the core material, lay 4-6 layers of PE fiber woven fabric prepreg in sequence. When laying each layer of prepreg, the fiber direction must be aligned (the warp angle between two adjacent layers of fiber woven fabric should be 90°). During the laying process, use a scraper to scrape and press along the surface of the prepreg in one direction to remove air between layers, ensuring that each layer of prepreg is tightly bonded to the core material or the previous layer of prepreg, without defects such as bubbles or wrinkles. Lay 4-6 layers of PE fiber woven fabric prepreg on the bottom surface of the core material in the same way. The number of layers on the top and bottom surfaces should be the same, and the total layer thickness should be controlled at 2-3mm to ensure the overall structure of the panel is symmetrical and to avoid deformation after hot pressing.

[0043] (ii) Scheme B (hybrid) layup operation

[0044] 1. The core layer positioning is consistent with Scheme A to ensure that the core material is firmly fixed and accurately positioned.

[0045] 2. Laying sequence: First, lay 1-2 layers of carbon fiber woven prepreg (as the surface layer) on the upper surface of the core material. The fiber direction of the carbon fiber prepreg is consistent with the length direction of the mat surface. After laying, scrape and press to remove air. Continue to lay 3-4 layers of PE fiber woven prepreg or unidirectional tape prepreg on top of the carbon fiber prepreg (the fiber direction angle between adjacent PE fiber materials is 45°-90°). Lay the lower surface of the core material in the reverse order of "3-4 layers of PE fiber prepreg + 1-2 layers of carbon fiber prepreg" to ensure that the upper and lower surface layers are carbon fiber materials and the inner layer is PE fiber material. The total lay-up thickness is consistent with Scheme A (2-3mm). During the laying process, strictly control the alignment accuracy of each layer. The misalignment error between layers is ≤±0.2mm.

[0046] (III) Preforming process

[0047] After the layup is completed, a release film (polytetrafluoroethylene material, 0.05-0.1mm thick) is placed on the layup surface. Then the upper mold is closed, and a pre-pressure of 0.5-1 atmosphere is applied and maintained for 10-15 minutes to allow the materials of each layer to initially adhere and shape, and to prevent the layup from shifting during hot pressing.

[0048] IV. Hot pressing curing

[0049] 1. Send the pre-formed mold into the hot press. After the mold is positioned, start the hot press and heat it according to the preset heating curve: heat from room temperature to 80℃ at a rate of 5-8℃ / min, and hold for 15-20min (preheating stage to allow the resin to initially flow); then heat to 130℃ at a rate of 3-5℃ / min (curing temperature, strictly controlled below the melting point of PE fiber to avoid damage to fiber properties). Monitor the mold cavity temperature in real time during the heating process, and control the temperature error within ±2℃.

[0050] 2. Pressurization operation: When the temperature reaches 130℃, start the pressurization system and gradually apply pressure to 10-15 atmospheres at a rate of 0.5-1 atmospheres / min. Keep the pressure uniform and the pressure difference between different areas of the mold cavity ≤ ±0.5 atmospheres to ensure that the resin flows fully and impregnates the fibers, and firmly bonds the honeycomb core material to the reinforcing layer, while expelling air bubbles between layers and inside the core material.

[0051] 3. Heat preservation and pressure holding: The resin is kept at 130℃ and 10-15 atmospheres for 60-90 minutes to ensure complete curing. During the curing process, the temperature and pressure feedback system of the hot press is used for real-time monitoring to ensure that the parameters are stable and without fluctuation.

[0052] V. Demolding and Post-processing

[0053] 1. After curing, turn off the heating system of the hot press and let the mold cool naturally to room temperature (cooling rate ≤10℃ / min, to avoid rapid cooling causing internal stress in the panel). When the mold temperature drops below 50℃, release the pressure, open the mold, and take out the formed panel blank.

[0054] 2. Trimming: Use a CNC trimming machine to remove excess material from the edges of the sheet blank. The trimming accuracy is controlled within ±0.1mm to ensure that the sheet blank shape meets the design dimensions and the edges are smooth and burr-free.

[0055] 3. Polishing: First, use 800-grit sandpaper to polish the surface of the panel to remove residual release agent and resin overflow. Then, use 1200-grit sandpaper for fine polishing to make the surface roughness Ra≤0.4μm. Avoid excessive polishing during the polishing process to prevent damage to the reinforcement layer.

[0056] 4. Drilling: Fix the polished plate onto the fixture of the CNC machining center. According to the preset hole position parameters (hole diameter is 3.0-3.5mm, hole spacing is 15-20mm), use a diamond drill bit to drill. The drilling speed is 3000-5000r / min, and the feed rate is 50-100mm / min. After drilling, use a deburring tool to remove burrs from the hole wall to ensure that the hole is smooth and unblocked.

[0057] 5. Coating treatment: First, the surface of the panel is degreased and dusted. Then, the primer is sprayed using electrostatic spraying, with a thickness of 20-30μm. After spraying, it is placed in an oven at 80-100℃ and dried for 30-40 minutes. After the primer dries, the topcoat is sprayed, with a thickness of 30-40μm. The drying temperature is 100-120℃ and the drying time is 40-60 minutes to ensure that the coating is uniform, without drips or bubbles, and that the adhesion meets the standards.

[0058] 6. Finished Product Inspection: The coated panel is inspected for dimensional accuracy, mechanical properties, and appearance quality. Dimensional error ≤ ±0.3mm, impact strength ≥ 25kJ / m. 2 The bending strength is ≥300MPa, and the surface is free of defects such as scratches, color difference, and coating peeling. Once the inspection is passed, it is considered a finished product.

[0059] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A Peak racket panel based on PE fiber hot pressing molding, characterized in that, It includes a core layer and a reinforcement layer, wherein the reinforcement layer is composited on the upper and lower surfaces of the core layer; The core layer is a polymer honeycomb core material or low-density closed-cell foam, used to provide thickness, shock absorption and disperse the energy of the impact. The main material of the reinforcing layer is ultra-high molecular weight polyethylene (PE) fiber woven fabric or unidirectional tape, and the reinforcing layer adopts one of the following two layup schemes: Option A (Balanced Type): Only ultra-high molecular weight polyethylene fiber woven fabric is used for layup; Option B (hybrid type): Mix and lay up ultra-high molecular weight polyethylene fiber material with a small amount of carbon fiber, with carbon fiber as the surface layer and ultra-high molecular weight polyethylene fiber material as the inner layer.

2. The Peak racket panel based on PE fiber hot pressing molding according to claim 1, characterized in that, The reinforcing layer is in the form of a prepreg, which is an ultra-high molecular weight polyethylene fiber material impregnated with a modified epoxy resin or thermoplastic polyurethane film. The modified epoxy resin or thermoplastic polyurethane film has good adhesion to the ultra-high molecular weight polyethylene fiber.

3. A method for preparing a Peak racket panel based on PE fiber hot pressing according to claim 2, characterized in that, Includes the following steps: (1) Mold preparation: High-precision steel molds are used. The mold cavity is a pre-set surface shape and includes wire holes. The mold surface is sprayed with a high-temperature release agent. (2) Lay-up and preforming: Place the cut core layer material into the lower mold, and lay the reinforcing layer prepreg layer by layer on the upper and lower surfaces of the core layer according to the designed lay-up sequence; (3) Hot pressing curing: Close the upper mold and send it into the hot press. Heat the temperature to the predetermined curing temperature of about 130°C (not exceeding the melting point of PE fiber), apply a high pressure of 10-15 atmospheres, and keep the temperature and pressure until the resin is completely cured. (4) Demolding and post-processing: After cooling, the mold is opened and the formed panel is taken out. Then, the edges are trimmed, polished, CNC machine tool is used for precise drilling, primer is sprayed and final coating is applied.

4. The method for preparing a Peak racket panel based on PE fiber hot pressing according to claim 3, characterized in that, The curing temperature in step (3) is strictly controlled below the melting point of ultra-high molecular weight polyethylene fiber to ensure that the fiber properties are not damaged.

5. The method for preparing a Peak racket panel based on PE fiber hot pressing according to claim 3, characterized in that, The resin system of the reinforcing layer prepreg in step (2) is a modified epoxy resin or thermoplastic polyurethane film specifically developed for PE fibers. The resin system can fully flow, impregnate the fibers and expel air bubbles during hot pressing.

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