High-strength and low-weight helmet carbon fiber skeleton and preparation method thereof

Abstract

The invention discloses a high-strength and low-weight helmet carbon fiber skeleton which comprises an inner-layer foaming supporting object, the outer surface of the inner-layer foaming supporting object is wrapped with a carbon fiber sheet layer, the inner-layer foaming supporting object is integrally designed to be of an arc-shaped structure, the width of the inner-layer foaming supporting object is gradually narrowed from the middle to the two ends, and the carbon fiber sheet layer is arranged on the outer surface of the inner-layer foaming supporting object. The thickness of the inner-layer foaming supporting object is gradually reduced from the bottom side edge to the upper side edge, the inner-layer foaming supporting object is obliquely arranged towards the center of the structure from bottom to top, the inner-layer foaming supporting object can provide attachment points for wrapping the carbon fiber sheet, the cut carbon fiber sheet is attached to the mark position of the inner-layer foaming supporting object, the manufacturing standard of the helmet carbon fiber framework can be guaranteed, and the manufacturing cost is reduced. After the carbon fiber sheets are solidified, cavities can be formed in the carbon fiber sheet layers, the supporting structure of the helmet carbon fiber framework is optimized, the actual material consumption can be greatly reduced, the burden of a wearer is reduced, meanwhile, the overall strength of the helmet carbon fiber framework is guaranteed, and dependence of the helmet framework on the thickness and the material consumption is reduced.

Description

Technical Field

[0001] The invention relates to a helmet frame, in particular to a high-strength and low-weight helmet carbon fiber frame and a preparation method thereof. Background Art

[0002] Helmets are a key piece of personal protective equipment used to protect the head from injury. They are widely used in motorcycle riding, cycling, industrial operations, various sports, and military operations. They are usually made of plastic, carbon fiber sheets, or composite materials, with an EPS foam lining inside to absorb impact, and may be covered with a PC shell or carbon fiber sheet skeleton outside to provide additional protection. The helmet design focuses on the ventilation system to improve wearing comfort, and the adjustment system can adapt to different head shapes. It must meet specific safety standards to ensure adequate protection in the event of an impact. When choosing a suitable helmet, you should consider the purpose, material, internal structure, external structure, ventilation system, adjustment system, and safety standards, and comply with local regulations to ensure the safety of the head during various activities. Chinese patent CN104497492B proposes a carbon fiber sheet / glass fiber fabric composite helmet shell, which is composed of a fiber fabric and a flame retardant resin; wherein the fibers constituting the fiber fabric are carbon fiber sheets and glass fibers; the fiber fabric is a double-sided sandwich structure, consisting of two layers and a middle sandwich; the upper and lower layers are woven from carbon fiber sheets; the middle sandwich is composed of glass fibers; and the glass fibers and carbon fiber sheets are connected in an inlaid manner, the fiber fabric is evenly distributed in the flame retardant resin, and the carbon fiber sheets and glass fibers account for 50-55% of the total volume of the helmet body. The mass fraction ratio of carbon fiber sheets to glass fibers is (1.5-4):1. Due to the use of a three-dimensional sandwich structure of reinforced fiber materials, the present invention takes advantage of the structural mechanics design, can well resist external force impacts perpendicular to the helmet, and at the same time significantly reduces the weight of the helmet shell, and has high puncture resistance, lateral rigidity, and electrical insulation. However, the above technology uses a skeleton made of carbon fiber sheet / glass fiber composite fabric to support the helmet shell, but the strength of the helmet shell is closely related to the thickness and material of the skeleton, which makes it difficult to achieve the optimal solution between the strength and weight of the skeleton structure. The present invention proposes a solution to the above problem as follows. Summary of the invention

[0003] The purpose of the present invention is to provide a high-strength and low-weight helmet carbon fiber skeleton and a preparation method thereof, which solves the problem that it is difficult to achieve an optimal solution between the strength and weight of the existing helmet skeleton structure.

[0004] The above technical objectives of the present invention are achieved through the following technical solutions: The present invention provides a high-strength and low-weight carbon fiber frame for a helmet, comprising an inner foam support, wherein the outer surface of the inner foam support is wrapped with a carbon fiber sheet layer, and the inner foam support is usually made of a lightweight foam material, such as PU or other similar lightweight plastic materials. As the name implies, the carbon fiber sheet layer is made of a carbon fiber material, and carbon fiber is well-known for its light weight, high strength and high stiffness, and is an ideal material for manufacturing high-performance helmets; Among them, the inner foam support is designed as an overall arc-shaped structure, its width is gradually narrowed from the middle to the two ends, its thickness is gradually thinned from the bottom edge to the upper edge, and the inner foam support is inclined from bottom to top toward the center of the structure. The arc-shaped design of the inner foam support and the design inclined from bottom to top toward the center of the structure help to better fit the shape of the head, provide more uniform support and pressure distribution, help to better disperse the impact force when impacted, reduce concentrated pressure on specific areas, thereby improving the protective performance of the helmet, the inner foam support The gradually narrowing design of the width and the gradually thinning design of the thickness can reduce the use of materials and reduce the weight of the helmet without sacrificing protective performance, while providing a better heat dissipation area on both sides of the helmet.

[0005] Preferably, a plurality of hollow grooves are provided on the inner foam support, and a corresponding settling portion or through hole is provided on the surface of the carbon fiber sheet layer corresponding to each hollow groove. The hollow grooves or through holes can reduce the use of materials, reduce the weight of the helmet and increase the adhesion of the upper and lower EPS of the helmet. The settling portions make the helmet less likely to deform when impacted, increase the structural strength of the carbon fiber sheet layer, and thus better protect the head. In a preferred embodiment, the slots of the carbon fiber skeleton are divided into a middle slot and side slots located on both sides of the middle slot, wherein one or more middle slots are non-penetrating structures, which help to enhance the strength of the carbon fiber sheet layer, and one or more side slots are penetrating structures, which help to establish a connection between the front and rear parts of the helmet, and can improve the overall strength of the helmet. It is worth noting that the penetrating structure is formed by wrapping the carbon fiber sheet around the edge of the hollow groove, and the non-penetrating structure not only wraps the carbon fiber sheet around the edge of the hollow groove, but also wraps the carbon fiber sheet around the rear side of the hollow groove.

[0006] Preferably, limiting parts are provided on both end faces of the carbon fiber layer, which can disperse the load when impacted, ensure a close fit between the carbon fiber layer and the EPS lining, increase the contact area between the two, and thus improve the strength of the connection.

[0007] The present invention also provides a method for preparing the high-strength and low-weight carbon fiber skeleton for a helmet as described above, comprising the following steps: Step 1: Heat the support mold to a certain temperature using a mold temperature controller and then take it out, pour PU material into the support mold for foaming, and demould after the reaction is completed to obtain the inner layer foam support; Step 2: cutting the uncured carbon fiber sheet into a desired shape according to a standard size, and coating the surface of the carbon fiber sheet with resin; Step 3: Adhere the cut carbon fiber sheet to the marked position of the inner foam support until the inner foam support is completely wrapped by the carbon fiber sheet; Step 4: Heat and shape the foam support wrapped with the carbon fiber sheet using a heating mold, so that the carbon fiber sheet wrapped outside the foam support is solidified to form a carbon fiber sheet layer; Step 5: After the heated mold is sufficiently cooled, the foamed support with the carbon fiber layer solidified on the surface is taken out to obtain a carbon fiber skeleton embryo; Step 6: Cut, grind and spray the carbon fiber skeleton blank to obtain a carbon fiber skeleton product that meets the design standards.

[0008] Preferably, the area where the carbon fiber skeleton needs to be locally strengthened is covered with multiple layers of carbon fiber sheets. By increasing the number of carbon fiber sheets, the mechanical properties of the helmet, such as tensile strength, compressive strength, tensile modulus and compression modulus, can be significantly improved, thereby improving the overall protective performance of the helmet. In a preferred embodiment, aramid cloth is additionally coated on both ends of the inner foam support, and carbon fiber sheets are coated in sequence at the rear and front of the combined structure, and the edge of the front carbon fiber sheet is wrapped around the rear carbon fiber sheet to form a carbon fiber layer. The aramid cloth and the carbon fiber cloth are composited to compensate for the brittleness of the carbon fiber, so that the composite material is not prone to brittle fracture when subjected to external force impact, and the impact resistance can be improved by up to 25%.

[0009] Preferably, the cut carbon fiber sheets are folded and formed by bending and bonding the uncured carbon fiber sheets to form a limiting portion, which helps to disperse the force when impacted and improve the protective ability of the helmet.

[0010] Beneficial effects: The present invention discloses a high-strength and low-weight carbon fiber frame for a helmet and a preparation method thereof. An inner foam support can provide an attachment point for wrapping a carbon fiber sheet. The cut carbon fiber sheet is adhered to a marked position of the inner foam support, so that the manufacturing standard of the carbon fiber frame for the helmet can be guaranteed. After the carbon fiber sheet is cured, a cavity can be formed inside the carbon fiber sheet layer, so that the support structure of the carbon fiber frame for the helmet is optimized, while the actual material consumption can be greatly reduced. While reducing the burden on the wearer, the overall strength of the carbon fiber frame for the helmet is guaranteed, and the dependence of the helmet frame on thickness and material consumption is reduced. The present invention discloses a high-strength and low-weight carbon fiber frame for a helmet and a preparation method thereof. At least one layer of carbon fiber sheet is covered on the edge area of ​​an inner foam support, so that the overall hardness of the carbon fiber sheet layer can be enhanced, and the carbon fiber sheet at the hollow groove is recessed into the interior of the carbon fiber frame structure of the helmet, so that the carbon fiber sheet layer has a three-dimensional support structure, and the support function of the front and back sides of the carbon fiber frame for the helmet is enhanced, and the connection strength between the two is improved. The application of these manufacturing processes improves the stability of the carbon fiber frame for the helmet; The present invention discloses a high-strength and low-weight carbon fiber frame for a helmet and a preparation method thereof. The size and thickness changes of the carbon fiber frame for the helmet can reduce the weight of the structure while maintaining sufficient strength where needed. The carbon fiber frame for the helmet is inclined from the bottom edge to the center, which helps to disperse the load, improve the stability of the structure, and further improve the high-strength characteristics of the carbon fiber frame for the helmet. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A three-dimensional structural diagram of a high-strength and low-weight carbon fiber frame for a helmet; Figure 2 A structural cross-sectional view of a high-strength and low-weight carbon fiber frame for a helmet; Figure 3 The structure diagram of the inner foam support in a high-strength and low-weight carbon fiber frame of a helmet; Figure 4 The present invention is a flow chart of a method for preparing a high-strength and low-weight carbon fiber skeleton for a helmet; Figure 5 A skeleton structure diagram of an application for a method for preparing a high-strength and low-weight carbon fiber skeleton for a helmet; Figure 6 A schematic diagram of a rigidity experiment of a carbon fiber skeleton for a helmet in a method for preparing the carbon fiber skeleton of a helmet with high strength and low weight; Figure 7 A HC-19 skeleton structure diagram of a method for preparing a high-strength and low-weight helmet carbon fiber skeleton; Figure 8 Schematic diagram of the stiffness experiment of HC-19 skeleton in the preparation method of high-strength and low-weight helmet carbon fiber skeleton.

[0012] Reference numerals: 100, inner foam support; 101, hollow groove; 200, carbon fiber sheet; 201, sedimentation part or through hole; 202, limit part. DETAILED DESCRIPTION

[0013] The following is only a preferred embodiment of the present invention, and the protection scope is not limited to this embodiment. All technical solutions under the concept of the present invention should belong to the protection scope of the present invention. At the same time, it should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

[0014] Examples, such as Figure 1-4 As shown, a method for preparing a high-strength and low-weight carbon fiber skeleton for a helmet comprises the following steps: Step 1: Heat the support mold to a certain temperature using a mold temperature controller and then take it out, pour PU material into the support mold for foaming, and demould after the reaction is completed, so as to obtain the inner layer foam support 100; Step 2: cutting the uncured carbon fiber sheet into a desired shape according to a standard size, and coating the surface of the carbon fiber sheet with resin; Step 3: Adhere the cut carbon fiber sheet to the marked position of the inner foam support 100 until the inner foam support 100 is completely wrapped by the carbon fiber sheet; Step 4: Heat and shape the foam support wrapped with the carbon fiber sheet using a heating mold, so that the carbon fiber sheet wrapped outside the foam support is solidified to form a carbon fiber sheet layer 200; Step 5: After the heated mold is sufficiently cooled, the foamed support 100 with the carbon fiber sheet 200 solidified on the surface is taken out to obtain a carbon fiber skeleton embryo; Step 6: Cut, grind and spray the carbon fiber skeleton blank to obtain a carbon fiber skeleton product that meets the design standards.

[0015] The high-strength and low-weight carbon fiber skeleton of the helmet comprises an inner foam support 100, the outer surface of the inner foam support 100 is wrapped with a carbon fiber sheet layer 200, and the area of ​​the carbon fiber skeleton that needs to be locally strengthened is covered with multiple layers of carbon fiber sheets; Among them, the inner layer foam support 100 is designed as an arc-shaped structure as a whole, its width is gradually narrowed from the middle to the two ends, its thickness is gradually thinned from the bottom edge to the upper edge, and the inner layer foam support 100 is inclined from bottom to top toward the center of the structure.

[0016] In this embodiment, a plurality of hollow grooves 101 are formed on the inner foam support 100 , and corresponding settling parts or through holes 201 are formed on the surface of the carbon fiber layer 200 corresponding to each hollow groove 101 .

[0017] In this embodiment, two end surfaces of the carbon fiber sheet 200 are provided with limiting portions 202 , and the limiting portions 202 are made by folding the cut carbon fiber sheets.

[0018] like Figure 4-8As shown, the high-strength and low-weight helmet carbon fiber frame obtained in the above example was subjected to a stiffness test with the helmet carbon fiber frame of the HC-19 carbon fiber sheet helmet.

[0019] 1. Purpose of the experiment The stiffness performance of the high-strength and low-weight helmet carbon fiber frame obtained in this example is compared with that of the helmet carbon fiber frame of the HC-19 carbon fiber helmet, and the performance of both under the stiffness test is evaluated.

[0020] 2. Experimental Materials and Equipment Experimental materials: several high-strength and low-weight helmet carbon fiber skeletons prepared from the above examples (hereinafter referred to as "application skeletons"), and several helmet carbon fiber skeletons of HC-19 carbon fiber sheet helmets (hereinafter referred to as "HC-19 skeletons").

[0021] Experimental equipment: universal material testing machine (with steel testing function), vernier caliper, electronic balance, constant temperature and humidity chamber.

[0022] 3. Experimental Procedure (1) Sample pretreatment: Use a vernier caliper to measure the dimensions of each skeleton and record key dimensional data such as length, width, and thickness.

[0023] Weigh each skeleton using an electronic balance and record the weight.

[0024] Place all skeletons in a constant temperature and humidity chamber at a temperature of 23±2°C and a relative humidity of 50±5% for 48 hours to allow the skeletons to reach a temperature and humidity equilibrium state.

[0025] (2) Experimental parameter setting: According to the size of the frame and the expected stiffness force, set the relevant parameters on the universal material testing machine. Use the three-point stiffness test method, set the span to two-thirds of the frame length, and set the loading speed to 2 mm / min.

[0026] (3) Testing process: Place the application frame and HC-19 frame on the test bench of the universal material testing machine in turn, ensuring that the frame is in the correct position and in good contact with the loading head and support points.

[0027] Start the testing machine, slowly apply stiffness force, and record the force value displayed by the testing machine and the corresponding skeleton stiffness displacement data in real time.

[0028] Continue loading until the skeleton shows obvious cracks, breaks, or reaches the set maximum displacement value (the maximum displacement value set in this experiment is twice the thickness of the skeleton). Stop the test and record the final force and displacement data.

[0029] Each type of skeleton was tested 10 times to obtain sufficient data for statistical analysis.

[0030] 4. Experimental results The average maximum stiffness force comparison is as follows: See Table 1 for details.

[0031] Table 1 - Steelness Test Application frame: After 10 tests, the average maximum stiffness value of the pressure at each location is taken (as shown in Table 1 above), which shows that it can withstand greater external forces during the stiffness process and has a strong ability to resist stiffness deformation.

[0032] HC-19 frame: After 10 tests, the average maximum stiffness value of each pressure is taken (as shown in Table 1 above), which shows that under the same test conditions, the application frame is better than the HC-19 frame in the maximum stiffness force index.

[0033] Specifically, the stiffness of the narrowest part of the applied frame is 3-6 times that of the HC-19 frame.

[0034] Statistical analysis results By statistically analyzing the stiffness test data of the two skeletons, the results showed that the differences between the applied skeleton and the HC-19 skeleton in terms of stiffness force and ultimate fracture were statistically significant (P<0.05), further verifying the advantages of the applied skeleton in stiffness performance.

[0035] 5. Conclusion Based on the results of the stiffness test, the high-strength and low-weight helmet carbon fiber skeleton obtained in this example is superior to the helmet carbon fiber skeleton of the HC-19 carbon fiber helmet in terms of stiffness force and ultimate fracture, indicating that the carbon fiber skeleton applied for has better performance in resisting stiffness deformation, maintaining structural stability and withstanding stiffness damage, and can provide more reliable structural support and protective performance for the helmet.

[0036] The helmet body prepared by the high-strength and low-weight helmet carbon fiber skeleton obtained in the above example and the HC-19 carbon fiber sheet helmet were subjected to a helmet collision absorption performance test according to GB24429-2009.

[0037] The helmet body of the present embodiment and the HC-19 carbon fiber helmet were subjected to the test treatment shown in Table 2 below: Table 2 - Helmet pre-test conditions Before testing, the helmet samples must be treated according to the provisions of Table 2. Each helmet sample should be treated in one way. The helmet samples after high temperature or low temperature treatment should be tested within 3 minutes. If it exceeds 3 minutes, the helmet samples should be put back into the incubator and treated for more than 5mm before testing. The helmet samples after water immersion treatment should be drained for 20 minutes before testing.

[0038] Collision point selection: Randomly select the four weakest parts in the test area as collision points, and perform one impact on each collision point. Two of the collision points use flat anvils, and the other two collision points use curb anvils (once along the length and width of the ventilation hole). The distance between the two impact points should not be less than 120mm.

[0039] Test steps: (a) The acceleration sensor is rigidly fixed on the center of the head-shaped coin. The angle between the sensor's sensitive axis and the normal of the head-shaped collision point should not be greater than 5°.

[0040] (b) Calibration of collision test device: Adjust the collision test platform head impact speed to make it collide with the standard test block at 5.44m / s (measured 40mm before the collision). Carry out three collisions with an interval of 75±15s under the same conditions, and the peak deviation of each collision acceleration is not more than 3%: Carry out calibration before and after the test. If the average acceleration peak after the test is 5% of the test, the test result is invalid.

[0041] The test results are shown in Table 3 below: Table 3 Table 3 above presents the test data of the helmet collision absorption performance of the helmet body with the high-strength and low-weight helmet carbon fiber skeleton of the application and the HC-19 carbon fiber sheet helmet under high, medium and low temperature conditions. The following conclusions can be drawn from the data: Compliance status: The helmets with the high-strength and low-weight carbon fiber frame and the HC-19 carbon fiber sheet helmets passed all the individual conclusions in various tests, indicating that they can basically meet the application standards under different temperatures and collision conditions and have certain protective performance.

[0042] Performance summary: On the one hand, after comprehensive testing under high, medium and low temperature conditions, the patented helmet carbon fiber frame performed well in most test scenarios, proving that its overall performance is relatively reliable and can provide effective head protection for the wearer; On the other hand, in the helmet collision absorption performance test, acceleration is a key parameter used to measure the helmet's ability to absorb impact energy during a collision. According to the GB24429-2009 standard, the helmet collision energy absorption performance test mainly examines two aspects: acceleration peak and action time. The magnitude of the acceleration peak directly reflects the degree of protection of the helmet to the head during a collision: the lower the acceleration peak, the better the helmet absorbs impact energy, and the stronger the protection performance for the wearer's head. Based on the above reasons, from the test data, the acceleration peak of the helmet with a high-strength and low-weight helmet carbon fiber skeleton under different temperature conditions is lower than that of the HC-19 carbon fiber sheet helmet, which shows that it has better performance in absorbing collision energy. Especially under low temperature conditions, the acceleration peak of the helmet is lower, showing superior low-temperature performance. This performance advantage means that in actual use, the helmet can provide more effective head protection for the wearer under various environmental conditions.

Claims

1. A high-strength and low-weight carbon fiber frame for a helmet, characterized in that: It comprises an inner foam support, the outer surface of which is wrapped with a carbon fiber sheet layer; Among them, the inner layer foam support is designed as an arc-shaped structure as a whole, its width is gradually narrowed from the middle to the two ends, its thickness is gradually thinned from the bottom edge to the upper edge, and the inner layer foam support is inclined from bottom to top toward the center of the structure.

2. A high-strength and low-weight carbon fiber frame for helmets according to claim 1, characterized in that: The inner foam support is provided with a plurality of hollow grooves, and the surface of the carbon fiber layer is provided with a matching settling part or through hole corresponding to each hollow groove.

3. A high-strength and low-weight carbon fiber frame for helmets according to claim 2, characterized in that: Limiting parts are arranged on both end surfaces of the carbon fiber layer.

4. A method for preparing a high-strength and low-weight carbon fiber skeleton for a helmet as claimed in any one of claims 1 to 3, characterized in that: The steps include: Step 1: Heat the support mold to a certain temperature using a mold temperature controller and then take it out, pour PU material into the support mold for foaming, and demould after the reaction is completed to obtain the inner layer foam support; Step 2: cutting the uncured carbon fiber sheet into a desired shape according to a standard size, and coating the surface of the carbon fiber sheet with resin; Step 3: Adhere the cut carbon fiber sheet to the marked position of the inner foam support until the inner foam support is completely wrapped by the carbon fiber sheet; Step 4: Heat and shape the foam support wrapped with the carbon fiber sheet using a heating mold, so that the carbon fiber sheet wrapped outside the foam support is solidified to form a carbon fiber sheet layer; Step 5: After the heated mold is sufficiently cooled, the foamed support with the carbon fiber layer solidified on the surface is taken out to obtain a carbon fiber skeleton embryo; Step 6: Cut, grind and spray the carbon fiber skeleton blank to obtain a carbon fiber skeleton product that meets the design standards.

5. The method for preparing a high-strength and low-weight carbon fiber skeleton for a helmet according to claim 4, characterized in that: The area of ​​the carbon fiber skeleton that needs to be locally strengthened is covered with multiple layers of carbon fiber sheets.

6. The method for preparing a high-strength and low-weight carbon fiber skeleton for a helmet according to claim 4, characterized in that: The limiting portion is formed by folding the cut carbon fiber sheets.

Images