Bulletproof helmet shell and preparation method thereof

Abstract

The invention provides a bulletproof helmet shell and a preparation method thereof. The preparation method comprises the following steps: providing a fiber material cutting piece; placing the fiber material cutting piece above a female die of a stretching pre-forming die, and clamping the edge of the fiber material cutting piece by utilizing a clamping die to fix the fiber material cutting piece; driving a male die of the stretching pre-forming die to move downwards and to be assembled with the female die, and then stretching and pre-forming the fiber material cutting piece to obtain a pre-formed helmet shell; the preformed helmet shell is transferred to a male mold of a forming mold, a female mold of the forming mold is driven to move downwards to be combined with the male mold, then hot press forming treatment is conducted on the preformed helmet shell, and after cooling, trimming treatment is conducted to obtain the bulletproof helmet shell. According to the bulletproof helmet shell, the bulletproof helmet shell is light in weight, small in depression value and excellent in bulletproof performance.

Description

Technical Field

[0001] This invention relates to the field of composite material structural design, specifically to a bulletproof helmet shell and its preparation method. Background Technology

[0002] In current military warfare, the emergence of various advanced technologies has led to more severe challenges to personnel safety, thus increasing the demand for and performance of bulletproof materials.

[0003] In the existing technology, ultra-high molecular weight polyethylene (UHMWPE) fiber and aramid fiber are commonly used to make non-metallic bulletproof helmets. Traditional bulletproof helmets usually use a method of cutting the fiber cloth (four-cut, six-cut, or eight-cut) to avoid the problem of material wrinkling during the molding process. However, this method will cause the continuous fibers to break, resulting in a reduction in the bulletproof performance of the helmet.

[0004] To address these issues, researchers typically employ a process that increases the number of fiber fabric layers and involves manual layer-by-layer stacking. However, this not only increases the helmet's mass (weight) but also compromises the consistency and stability of ballistic protection performance across different areas of the helmet. Therefore, finding a method that eliminates the need for cutting or trimming the fiber fabric, resolves the wrinkling issues that arise during the pressing process, and improves the consistency and stability of ballistic protection performance across different areas of the bulletproof helmet shell is of paramount importance.

[0005] How to manufacture a bulletproof helmet shell that is lightweight, has a small dent value, and has excellent ballistic performance has become a research hotspot in this field. Summary of the Invention

[0006] The present invention can produce a bulletproof helmet shell and a method thereof, which combines lightweight, low dent value and excellent ballistic performance.

[0007] This invention provides a method for preparing a bulletproof helmet shell, comprising: providing a fiber material sheet; placing the fiber material sheet above the female mold of a stretching preforming mold, and using a clamping mold to clamp the edge of the fiber material sheet to fix it; driving the male mold of the stretching preforming mold to move downward and close with the female mold, and then stretching and preforming the fiber material sheet to obtain a preformed helmet shell; transferring the preformed helmet shell to the male mold of a forming mold, driving the female mold of the forming mold to move downward and close with the male mold, and then hot-pressing the preformed helmet shell; after cooling, trimming to obtain the bulletproof helmet shell.

[0008] Optionally, the fiber material cut piece is square in shape; preferably, the side length of the fiber material cut piece is 480mm~550mm.

[0009] Optionally, the fiber material sheet includes one or more of ultra-high molecular weight polyethylene nonwoven fabric, ultra-high molecular weight polyethylene woven fabric, aramid fiber nonwoven fabric, and aramid fiber woven fabric.

[0010] Optionally, the areal density of the fiber material pieces, the areal density of the bulletproof helmet shell, and the number of fiber material pieces satisfy the following: the number of fiber material pieces = tensile coefficient × (areal density of the bulletproof helmet shell ÷ areal density of the fiber material pieces), wherein the tensile coefficient is 0.7~0.9.

[0011] Optionally, the areal density of the fiber material sheet is 40 g / m². 2 ~360g / m 2 ; and / or, the areal density of the bulletproof helmet shell is 7.0 kg / m³. 2 ~9.2kg / m 2 ; and / or, the tensile coefficient is 0.8 to 0.9.

[0012] Optionally, the mass of the clamping mold is 10kg to 50kg.

[0013] Optionally, the temperature of the stretch preforming is 60℃~90℃; and / or, the pressure of the stretch preforming is 5MPa~10MPa; and / or, the time of the stretch preforming is 2min~10min.

[0014] Optionally, the temperature during the hot pressing process is 120℃~135℃; and / or, the pressure during the hot pressing process is 18MPa~25MPa; and / or, the time during the hot pressing process is 20min~50min.

[0015] The present invention also provides a bulletproof helmet shell prepared according to the above method.

[0016] Optionally, the mass of the bulletproof helmet shell is 0.95kg to 1.20kg, and the dent value is 8mm to 15mm.

[0017] This invention provides a bulletproof helmet shell and its preparation method, which has at least the following beneficial effects: In the preparation method of the bulletproof helmet shell of this invention, on the one hand, fiber cloth (non-woven or woven fabric) is used as raw material for non-cutting, and then the bulletproof helmet shell is pressed. The shell area corresponding to the non-woven fabric is not cut, avoiding fiber breakage caused by traditional petal cutting methods, ensuring fiber continuity, and greatly improving the bulletproof performance of the helmet. On the other hand, stretching pre-forming greatly reduces wrinkles in the fiber cloth during the pressing process, ensuring the consistency of thickness at different locations of the bulletproof helmet shell, thereby ensuring the consistency and stability of the bulletproof performance at different locations of the helmet shell. Furthermore, one-time pre-pressing avoids the traditional manual layup process, improving the bulletproof performance of the helmet shell, reducing the weight of the helmet shell, greatly improving production efficiency, and eliminating batch deviations present in manual layup, ensuring the stability of the production process. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the stretching preforming mold for the bulletproof helmet shell provided by the present invention;

[0020] Figure 2 A schematic diagram of the cut-out fiber material pattern for the bulletproof helmet shell provided by the present invention;

[0021] Figure 3 This is a schematic diagram of the pattern for cutting petals using the traditional four-cut petal cutting method.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1- The male mold of the stretch preforming mold; 2- The fiber material cut piece; 3- The female mold of the stretch preforming mold; 4- The clamping mold of the stretch preforming mold. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Existing patent (CN202311699962.6) discloses a structurally stable axial lining yarn structure. This structure uses a combination of horizontal partial knitting and loop-type take-up and release knitting methods to create a one-time forming of the bulletproof helmet preform. A resin membrane infiltration process is then employed for molding to produce the bulletproof helmet. However, this method requires sophisticated equipment and involves complex processes.

[0026] Based on this, embodiments of the present invention provide a method for preparing a bulletproof helmet shell, comprising: providing a fiber material sheet; placing the fiber material sheet above the female mold of a stretching preforming mold, and using a clamping mold to clamp the edge of the fiber material sheet to fix it; driving the male mold of the stretching preforming mold to move downward and close with the female mold, and then stretching and preforming the fiber material sheet to obtain a preformed helmet shell; transferring the preformed helmet shell to the male mold of a forming mold, driving the female mold of the forming mold to move downward and close with the male mold, and then hot-pressing the preformed helmet shell; after cooling, performing edge trimming to obtain a bulletproof helmet shell.

[0027] According to research and analysis, in the method for preparing the bulletproof helmet shell of this invention, on the one hand, fiber cloth (non-woven or woven fabric) is used as raw material for seamless cutting, followed by pressing of the bulletproof helmet shell. The shell area corresponding to the non-woven fabric is not cut, thus avoiding the traditional petal-cutting method (such as...). Figure 3 The fiber breakage caused by the pre-forming process (as shown) ensures fiber continuity and greatly improves the ballistic protection performance of the helmet. On the other hand, the clamping action of the clamping mold fixes the fiber material pieces, which greatly reduces wrinkles in the fiber cloth during the pressing process during the stretching pre-forming process. This ensures the consistency of thickness at different locations of the helmet shell, thereby ensuring the consistency and stability of the ballistic protection performance at different locations of the helmet shell. In addition, the one-time pre-pressing process avoids the traditional manual layup process, improves the ballistic protection performance of the helmet shell, reduces the weight of the helmet shell, greatly improves production efficiency, and eliminates batch deviations that exist in manual layup, ensuring the stability of the production process.

[0028] In practice, the process of providing fiber material cut pieces may include: using a cutting machine to cut the fiber fabric raw material into fiber material cut pieces according to the designed layout.

[0029] The cutting machine can be a fully automatic cutting machine.

[0030] The raw material for the fiber cloth can be fiber cloth impregnated with a resin matrix.

[0031] In some embodiments, the shape of the fiber material cut piece is square (e.g., Figure 2 (As shown).

[0032] Preferably, the side length of the fiber material piece is 480mm to 550mm, for example, 480, 490, 500, 510, 520, 530, 540, 550mm or any combination thereof.

[0033] When the side length of the fiber material cut pieces meets the above range, it is beneficial for fixing and pressing during the stretching preforming process, which helps to ensure the consistency of the thickness of different positions of the bulletproof helmet shell, while taking into account the light weight, small indentation value and excellent ballistic performance of the bulletproof helmet shell.

[0034] In some embodiments, the fiber material cut sheet includes one or more of ultra-high molecular weight polyethylene nonwoven fabric, ultra-high molecular weight polyethylene woven fabric, aramid fiber nonwoven fabric, and aramid fiber woven fabric.

[0035] The term "ultra-high molecular weight" refers to a molecular weight greater than 1 million.

[0036] Using the aforementioned fiber material pieces can improve the bulletproof effect of the helmet shell, reduce the weight of the helmet shell, and decrease the dent value.

[0037] In some embodiments, the areal density of the fiber material pieces, the areal density of the bulletproof helmet shell, and the number of fiber material pieces satisfy the following: number of fiber material pieces = tensile coefficient × (areal density of the bulletproof helmet shell ÷ areal density of the fiber material pieces), wherein the tensile coefficient is 0.7~0.9.

[0038] The elongation factor can be 0.7 to 0.9, for example, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9 or any combination thereof.

[0039] Meeting the above conditions regarding the areal density of the fiber material pieces, the areal density of the bulletproof helmet shell, and the number of fiber material pieces is beneficial for determining the number of fiber material pieces, reducing the weight of the bulletproof helmet shell, lowering the indentation value, and improving the bulletproof effect of the bulletproof helmet shell.

[0040] In some embodiments, the areal density of the fiber material sheet is 40 g / m². 2 ~360g / m 2 The areal density of the bulletproof helmet shell is 7.0 kg / m³. 2 ~9.2kg / m 2 .

[0041] Areal density refers to the mass per unit area.

[0042] The areal density of the fiber material sheet is 40 g / m².2 ~360g / m 2 For example, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360 g / m³ 2 Or a range consisting of any two of these. A fiber material sheet having a areal density within the above range helps improve the ballistic protection performance of the helmet shell while reducing its weight.

[0043] The areal density of the bulletproof helmet shell is 7.0 kg / m³. 2 ~9.2kg / m 2 For example, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2 kg / m 2 Or a range consisting of any two of these. A bulletproof helmet shell with a surface density within the above range helps improve its ballistic protection performance while reducing its weight.

[0044] Based on the relationship between the areal density of the fiber material pieces, the areal density of the bulletproof helmet shell, the tensile coefficient, and the number of fiber material pieces, the number of fiber material pieces can be 12 to 210 pieces, for example, 12, 20, 35, 40, 50, 58, 65, 100, 135, 150, 180, 200, 210 pieces or any combination thereof.

[0045] The fiber material cut piece is placed above the female mold of the stretch preforming mold, and the edge of the fiber material cut piece is clamped and fixed by the clamping mold. Specifically, it can include: laying a layer of release film on the top and bottom of the calculated required fiber material cut piece, placing it flat on the female mold of the stretch preforming mold, and clamping the edge of the fiber material cut piece to fix it.

[0046] Stretch preforming is a pre-process that involves stretching and pressing fiber materials before they are fully formed (into a bulletproof helmet shell) to achieve an intermediate state (pre-formed shell) that is close to the final shape (bulletproof helmet shell) or has certain properties (bulletproof performance). This process can prevent wrinkles from appearing on the fiber material pieces during the pressing process, thereby reducing the weight of the bulletproof helmet shell, lowering the indentation value, and improving the bulletproof performance of the bulletproof helmet shell.

[0047] Figure 1The image shows a stretching preforming mold for a bulletproof helmet shell without cutouts provided by the present invention, wherein 1-the male mold of the stretching preforming mold, 2-a fiber material cut piece, 3-the female mold of the stretching preforming mold, and 4-the clamping mold of the stretching preforming mold.

[0048] During the stretching preforming process, the fiber material piece (2) is placed above the female mold (3) of the stretching preforming mold, and the edge of the fiber material piece (2) is clamped and fixed by the clamping mold (4); the male mold (1) of the stretching preforming mold is driven to move downward and close the mold with the female mold, and then the fiber material piece is stretched and preformed to obtain a preformed helmet shell.

[0049] The release liner can be a fluoropolymer release liner, such as one or more of polytetrafluoroethylene (PTFE) coated fiberglass cloth, ethylene-tetrafluoroethylene copolymer film (ETFE), and full polytetrafluoroethylene (PTFE) film. In the manufacturing process of bulletproof helmet shells, the release liner facilitates demolding and lubrication, preventing the fiber structure of the fibrous material from sticking to the mold and causing damage to the fiber material during stretching and preforming, thereby improving the uniformity of the bulletproof performance of the helmet shell.

[0050] In some embodiments, the mass of the clamping mold is 10 kg to 50 kg, for example, a range of 10, 15, 20, 25, 30, 35, 40, 45, 50 kg or any combination thereof.

[0051] Meeting the above-mentioned quality range for the clamping mold is beneficial for better fixing of the fiber material pieces on the stretching preforming mold, which can prevent the appearance of wrinkles on the fiber material pieces during the pressing process, thereby reducing the weight of the bulletproof helmet shell, reducing the indentation value, and improving the ballistic protection performance of the bulletproof helmet shell.

[0052] The male mold of the driving stretching preforming die moves downward and closes with the female mold, then stretches and preforms the fiber material sheet to obtain a preformed helmet shell. It is understood that the above stretching preforming needs to be carried out under certain temperature, pressure, and time conditions.

[0053] In some embodiments, the temperature of the stretch preforming is 60℃~90℃; the pressure of the stretch preforming is 5MPa~10MPa; and the stretch preforming time is 2min~10min.

[0054] The stretch preforming temperature is 60℃~90℃, for example, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or any combination thereof. A stretch preforming temperature within this range facilitates uniform stretching of the fiber material, eliminates wrinkles, maintains the continuity of the fiber structure, ensures consistent thickness at different locations on the bulletproof helmet shell, improves the consistency and stability of the bulletproof performance at different locations on the helmet shell, reduces the weight of the helmet shell, and lowers the dent value.

[0055] The tension preforming pressure is 5MPa to 10MPa, for example, 5, 6, 7, 8, 9, 10MPa or any combination thereof. Meeting this tension preforming pressure range facilitates uniform stretching of the fiber material, eliminates wrinkles, maintains the continuity of the fiber structure, ensures consistent thickness at different locations on the bulletproof helmet shell, improves the consistency and stability of the bulletproof performance at different locations on the helmet shell, reduces the weight of the helmet shell, and lowers the dent value.

[0056] The stretching preforming time is 2 to 10 minutes, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10 minutes or any combination thereof. Meeting this stretching preforming time range facilitates uniform stretching of the fiber material, eliminates wrinkles, maintains the continuity of the fiber structure, ensures consistent thickness at different locations on the bulletproof helmet shell, improves the consistency and stability of the bulletproof performance at different locations on the helmet shell, reduces the weight of the helmet shell, and lowers the indentation value.

[0057] The pre-formed helmet shell is transferred to the male mold of the forming mold. The female mold of the forming mold moves downward to close with the male mold. Then, the pre-formed helmet shell is subjected to hot pressing. After cooling, it is trimmed to obtain the bulletproof helmet shell. Specifically, the above hot pressing process must be carried out according to a set hot pressing program. The hot pressing program includes conditions such as temperature, pressure, and time during the hot pressing process.

[0058] The temperature during the hot pressing process can be 120℃~135℃, for example, 120℃, 121℃, 122℃, 123℃, 124℃, 125℃, 126℃, 127℃, 128℃, 129℃, 130℃, 131℃, 132℃, 133℃, 134℃, 135℃ or any combination thereof.

[0059] The pressure during the hot pressing process can be 18MPa to 25MPa, for example, 18, 19, 20, 21, 22, 23, 24, 25MPa or any combination thereof.

[0060] The hot pressing process can take 20 to 50 minutes, for example, 20, 25, 30, 35, 40, 45, 50 minutes or any combination thereof.

[0061] The trimming machine used in the trimming process can be one or more of laser cutting machines and band saws.

[0062] The preparation method of this invention utilizes uncut fiber material sheets as raw materials, and prepares a bulletproof helmet shell through steps of raw material cutting, stretching preforming, hot pressing, and edge trimming. The bulletproof helmet shell prepared using the above method avoids the problems of fiber breakage and decreased ballistic performance, production efficiency, and poor stability caused by traditional bulletproof helmet shells (which involve cutting fiber cloth, such as with four, six, or eight cuts) and manual layering.

[0063] This invention also provides a bulletproof helmet shell prepared according to the above method. This bulletproof helmet shell is lightweight, has a low dent value, and excellent ballistic protection performance.

[0064] The helmet shell weighs between 0.95kg and 1.20kg, and has a dent value between 8mm and 15mm.

[0065] The weight of a bulletproof helmet shell can range from 0.95 kg to 1.20 kg, for example, 0.95, 1.00, 1.08, 1.20 kg, or any combination thereof. When the weight meets the above range, the bulletproof helmet shell has a relatively light weight.

[0066] According to the Level 2 requirements of the GA293-2012 standard "Police Bulletproof Helmets and Face Shields", the bulletproof performance of the helmet shell was tested. The dent value at different locations on the bulletproof helmet shell can be 8mm to 15mm, for example, 8, 9, 10, 11, 12, 13, 14, 15mm or any combination thereof. When the dent value meets the above range, the bulletproof helmet shell has excellent bulletproof performance.

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0068] Example 1

[0069] This embodiment provides a method for preparing a bulletproof helmet shell.

[0070] A fully automatic cutting machine is used to cut materials with a surface density of 120g / m³. 2 The ultra-high molecular weight polyethylene nonwoven fabric is cut into square fiber material pieces with a side length of 510mm and a tensile coefficient of 0.81. The number of ultra-high molecular weight polyethylene nonwoven fabric pieces can be calculated to be 58 pieces.

[0071] A layer of release film is placed on the top and bottom of the 58-layer fiber material cut sheet, and placed above the female mold of the stretching preforming mold. The edges of the fiber material cut sheet are clamped and fixed by the clamping mold, which weighs 20 kg.

[0072] The male mold of the driving stretching preforming mold moves downward and closes with the female mold. The stretching preforming pressure is 5MPa, the stretching preforming temperature is 70℃, and the stretching preforming time is 10min, thus obtaining a preformed helmet shell.

[0073] The pre-formed helmet shell is transferred to the male mold of the forming mold, and the female mold of the forming mold is driven to move downward to close with the male mold. The temperature during the hot pressing process is 123℃, the pressure during the hot pressing process is 21MPa, and the time during the hot pressing process is 30min. After cooling, the edges are trimmed using a laser cutting machine to obtain the bulletproof helmet shell.

[0074] Example 2

[0075] This embodiment provides a method for preparing a bulletproof helmet shell.

[0076] A fully automatic cutting machine is used to cut materials with a surface density of 190g / m³. 2 The aramid fiber woven fabric is cut into square fiber material pieces with a side length of 510mm and a tensile coefficient of 0.72. It can be calculated that the number of aramid fiber woven fabric pieces is 35.

[0077] A layer of release film is laid on the top and bottom of the 35-layer fiber material cut sheet, and placed above the female mold of the stretching preforming mold. The edges of the fiber material cut sheet are clamped and fixed by the clamping mold, which weighs 30 kg.

[0078] The male mold of the driving stretching preforming mold moves downward and closes with the female mold. The stretching preforming pressure is 8MPa, the stretching preforming temperature is 90℃, and the stretching preforming time is 5min, thus obtaining a preformed helmet shell.

[0079] The pre-formed helmet shell is transferred to the male mold of the forming mold, and the female mold of the forming mold is driven to move downward to close with the male mold. The temperature during the hot pressing process is 135℃, the pressure during the hot pressing process is 20MPa, and the time during the hot pressing process is 35min. After cooling, the edges are trimmed using a laser cutting machine to obtain the bulletproof helmet shell.

[0080] Example 3

[0081] This embodiment provides a method for preparing a bulletproof helmet shell.

[0082] A fully automatic cutting machine is used to cut materials with a surface density of 50g / m². 2 The ultra-high molecular weight polyethylene woven fabric is cut into square fiber material pieces with a side length of 550mm and a tensile coefficient of 0.89. The number of ultra-high molecular weight polyethylene woven fabric pieces can be calculated to be 135 pieces.

[0083] A layer of release film is laid on the top and bottom of the 135-layer fiber material cut sheet, and placed above the female mold of the stretching preforming mold. The edges of the fiber material cut sheet are clamped and fixed by the clamping mold, which weighs 10 kg.

[0084] The male mold of the driving stretching preforming mold moves downward and closes with the female mold. The stretching preforming pressure is 10MPa, the stretching preforming temperature is 60℃, and the stretching preforming time is 2min to obtain a preformed helmet shell.

[0085] The pre-formed helmet shell is transferred to the male mold of the forming mold, and the female mold of the forming mold is driven to move downward to close with the male mold. The temperature during the hot pressing process is 120℃, the pressure during the hot pressing process is 25MPa, and the time during the hot pressing process is 50min. After cooling, the edges are trimmed using a laser cutting machine to obtain the bulletproof helmet shell.

[0086] Example 4

[0087] This embodiment provides a method for preparing a bulletproof helmet shell.

[0088] A fully automatic cutting machine is used to cut materials with a surface density of 360g / m³. 2 Aramid fiber nonwoven fabric is cut into square fiber material pieces with a side length of 480mm and a tensile coefficient of 0.71. It can be calculated that the number of aramid fiber nonwoven fabric pieces is 20.

[0089] A layer of release film is placed on the top and bottom of the 20-layer fiber material cut sheet, and placed above the female mold of the stretching preforming mold. The edges of the fiber material cut sheet are clamped and fixed by the clamping mold, which weighs 50 kg.

[0090] The male mold of the driving stretching preforming mold moves downward and closes with the female mold. The stretching preforming pressure is 5MPa, the stretching preforming temperature is 70℃, and the stretching preforming time is 10min, thus obtaining a preformed helmet shell.

[0091] The pre-formed helmet shell is transferred to the male mold of the forming mold, and the female mold of the forming mold is driven to move downward to close with the male mold. The temperature during the hot pressing process is 130℃, the pressure during the hot pressing process is 18MPa, and the time during the hot pressing process is 20min. After cooling, the edges are trimmed using a laser cutting machine to obtain the bulletproof helmet shell.

[0092] Comparative Example 1

[0093] A fully automatic cutting machine is used to cut materials with a surface density of 120g / m³. 2 Ultra-high molecular weight polyethylene nonwoven fabric is cut into circular four-cut petal pieces with a diameter of 500mm.

[0094] The 40 layers of the above-mentioned cut pieces are rotated and laid out at a rotation angle of 15°. 20 layers of circular reinforcing sheets with a diameter of 180mm are then laid on the top of the helmet. The helmet is placed on the male mold of the molding die, and the female mold of the molding die is driven to move downwards to close with the male mold. The temperature during the hot pressing process is 135℃, the pressure is 20MPa, and the time is 35min. After cooling, the edges are trimmed using a laser cutting machine to obtain the bulletproof helmet shell.

[0095] The bulletproof helmets prepared in the above embodiments and comparative examples were weighed and their bulletproof performance was tested according to Level 2 requirements of the GA293-2012 standard "Police Bulletproof Helmets and Face Shields". The results are shown in Table 1, with the actual orientation of the bulletproof helmet shell as the reference.

[0096] Table 1. Comparison of ballistic protection performance of bulletproof helmet shells

[0097]

[0098] Conclusion and analysis: The ballistic performance test results show that the bulletproof helmet shells without cuts prepared by the present invention (Examples 1-4) are lighter in weight and have smaller indentation values ​​in all directions, exhibiting superior ballistic performance and consistent and stable ballistic performance in different locations.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a bulletproof helmet shell, characterized in that, include: Provide fiber material cut pieces; The fiber material cut piece is placed above the female mold of the stretching preforming mold, and the edge of the fiber material cut piece is clamped and fixed by the clamping mold. The male mold of the stretching preforming mold is driven to move downward and close with the female mold, and then the fiber material piece is stretched and preformed to obtain a preformed helmet shell; The pre-formed helmet shell is transferred to the male mold of the forming mold, and the female mold of the forming mold is driven to move downward to close with the male mold. Then, the pre-formed helmet shell is subjected to hot pressing forming. After cooling, the edges are trimmed to obtain the bulletproof helmet shell.

2. The method for preparing the bulletproof helmet shell according to claim 1, characterized in that, The fiber material sheet is square in shape; Preferably, the side length of the fiber material cut piece is 480mm to 550mm.

3. The method for preparing a bulletproof helmet shell according to claim 1 or 2, characterized in that, The fiber material cut pieces include one or more of ultra-high molecular weight polyethylene nonwoven fabric, ultra-high molecular weight polyethylene woven fabric, aramid fiber nonwoven fabric, and aramid fiber woven fabric.

4. The method for preparing a bulletproof helmet shell according to any one of claims 1-3, characterized in that, The areal density of the fiber material pieces, the areal density of the bulletproof helmet shell, and the number of fiber material pieces satisfy the following: the number of fiber material pieces = tensile coefficient × (areal density of the bulletproof helmet shell ÷ areal density of the fiber material pieces), wherein the tensile coefficient is 0.7 to 0.

9.

5. The method for preparing a bulletproof helmet shell according to claim 4, characterized in that, The areal density of the fiber material sheet is 40 g / m³. 2 ~360g / m 2 ; And / or, the areal density of the bulletproof helmet shell is 7.0 kg / m³. 2 ~9.2kg / m 2 .

6. The method for preparing a bulletproof helmet shell according to any one of claims 1-5, characterized in that, The mass of the clamping mold is 10kg to 50kg.

7. The method for preparing a bulletproof helmet shell according to any one of claims 1-6, characterized in that, The temperature for stretching preforming is 60℃~90℃; And / or, the pressure of the stretch preforming is 5MPa to 10MPa; And / or, the stretching preforming time is 2 min to 10 min.

8. The method for preparing a bulletproof helmet shell according to any one of claims 1-7, characterized in that, The temperature during the hot pressing process is 120℃~135℃; And / or, the pressure during the hot pressing process is 18MPa to 25MPa; And / or, the time during the hot pressing process is 20 min to 50 min.

9. A bulletproof helmet shell, characterized in that, It was prepared according to the method of claims 1 to 8.

10. The bulletproof helmet shell according to claim 9, characterized in that, The mass of the bulletproof helmet shell is 0.95kg to 1.20kg, and the dent value is 8mm to 15mm.

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