A molding method for a lightweight, high-protection PE bulletproof helmet

Abstract

The present invention discloses a method for forming a lightweight, high-protection PE bulletproof helmet, comprising: 1. pattern design and cutting; 2. preparing a helmet shell paving body; 3. preheating and forming; 4. hot pressing and forming; 5. hot pressing and cooling; 6. trimming and punching; 7. gluing edge sealing strips; 8. internal and external surface treatment; 9. spraying polyurea; and 10. assembling a suspension system and a cap cover. The present invention uses bi-orthogonal PEUD prepreg and PE plain weave prepreg fabric as the main structure and surface fabric of the helmet shell, respectively, which is beneficial for improving the bending strength and resistance to inward deformation of the helmet shell, reducing the possibility of blunt trauma. Combined with the design of the shape and laying method of each surface layer in the helmet shell paving body, the lateral rigidity and top rigidity of the helmet shell are greatly enhanced, thereby improving the protective performance of the PE bulletproof helmet and achieving lightweighting.

Description

Technical Field

[0001] The invention belongs to the technical field of bulletproof protective equipment and materials, and particularly relates to a molding method for a lightweight and highly protective PE bulletproof helmet. Background Art

[0002] A bulletproof helmet primarily consists of a shell, liner, and suspension assembly. The shell absorbs and mitigates the impact of bullets and shrapnel through material deformation, preventing shell fragments from injuring the head. The lining provides ventilation, sweat absorption, warmth retention, and shock absorption. The suspension assembly separates the shell and liner to accommodate soldiers with varying head shapes. Therefore, the design and fabrication of the shell are crucial to ensuring helmet performance.

[0003] From the perspective of technological research and development, there are two main ways to achieve lightweight and highly protective bulletproof helmet shells: one is to develop new materials with better overall performance, including ultra-high performance fibers and resin materials; the other is to fully explore and utilize the functional properties of existing materials, including designing the optimal fabric structure and optimizing the molding process.

[0004] Based on the raw materials, lightweight composite bulletproof helmets are currently divided into two categories: aramid composite helmets and PE composite helmets. The properties of aramid fibers and ultra-high molecular weight polyethylene (PE) fibers currently used in bulletproof composite materials on the market are shown in Table 1.

[0005] Table 1

[0006]

[0007] As shown in Table 1, compared to aramid fiber, ultra-high molecular weight polyethylene (PE) fiber has a density of only 67% of aramid fiber, yet its strength and modulus are approximately 1.67 times and 1.72 times those of aramid fiber, respectively. Compared to carbon fiber, UHMWPE fiber has a density of only 52% and 54% of high-modulus and high-strength carbon fibers, respectively, yet its strength is superior to both, and its modulus is similar to that of high-strength carbon fibers. Compared to steel wire, UHMWPE fiber has a density of only 12% of steel wire, yet its strength and modulus are approximately 1.8 times and 4.8 times those of steel wire, respectively. Furthermore, UHMWPE fiber also exhibits superior elongation compared to other commonly used materials. Therefore, compared to materials such as aramid fiber, UHMWPE fiber is an ideal material for lightweight, high-protection ballistic helmets. However, PE has a melting point of only around 150°C, which places high demands on hot press molding processes and resin matching.

[0008] At the same time, the organizational structure of PE also plays a significant role in its ballistic performance. The reinforcement structure used to reinforce bulletproof composite materials can be divided into three categories based on the differences in yarn arrangement direction and dimension: UD (Unidirectional) unidirectional fabric or weftless fabric, two-dimensional woven fabric, and three-dimensional fabric. UD, due to the absence of curved yarns, fully retains the excellent properties of high-performance fibers, allowing for a wider range of impact energy transfer and greater energy absorption, which is more conducive to improving the fabric's bending strength and resistance to inward deformation, thereby reducing the possibility of blunt trauma and significantly improving the material's ballistic performance. Therefore, PE fibers used in bulletproof materials are typically in the form of UD, where each layer of fibers is oriented at 0° / 90° and bonded by a thermoplastic resin matrix to form a dual-orthogonal PEUD material.

[0009] Therefore, existing research on PE ballistic helmets primarily consists of multiple layers of PEUD fabric sheets stacked one on top of the other, then formed through high-temperature, high-pressure composite pressing. Given the weight limits imposed on ballistic helmets, the PEUD sheet layup and stacking structure, as well as the molding method, directly impact the protective performance of PE ballistic helmets. Summary of the Invention

[0010] The technical problem addressed by the present invention is to address the shortcomings of the prior art by providing a method for forming a lightweight, high-protection PE bulletproof helmet. This method utilizes bi-orthogonal PEUD prepreg and PE plain weave prepreg fabric as the main structure and surface fabric of the helmet shell, respectively. This method improves the shell's bending strength and resistance to inward deformation, reducing the likelihood of blunt force injuries. Furthermore, by designing the shape and placement of each surface layer within the shell's paving, the lateral and top rigidity of the helmet shell are significantly enhanced, improving the protective performance of the PE bulletproof helmet while achieving lightweighting.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is: a molding method of a lightweight high-protection PE bulletproof helmet, characterized in that the method comprises the following steps:

[0012] Step 1: Lofting design and cutting: Perform lofting design on the target product, PE bulletproof helmet, and then cut the bi-orthogonal PEUD prepreg according to the design results to obtain 1# large surface, 2# small surface and 3# small surface, and cut the PE plain weave prepreg fabric to obtain 4# large surface;

[0013] The shape of the 1# large surface is a combination of a 3 / 4 area circle and a square with a side length equal to the radius of the 3 / 4 area circle, and the two outer radii of the 3 / 4 area circle completely coincide with two adjacent sides of the square. In the 1# large surface, four seams are opened in sequence from the circumference to the center of the circle along the two sides and the extension line where the 3 / 4 area circle coincides with the square, and the lengths of the four seams are all equal and less than the radius of the 3 / 4 area circle in the 1# large surface;

[0014] The 2# small face is a semicircle with an indented triangular notch at the center, and the bottom edge of the indented triangular notch coincides with the diameter of the semicircle;

[0015] The 3# small face is circular;

[0016] The 4# large surface is a square, and the 4# large surface has 4 tailorings in the direction perpendicular to the four sides of the square from the four sides to the center of the square, and the lengths of the 4 tailorings are equal and less than half the side length of the 4# large surface;

[0017] Step 2, prepare the helmet shell paving body: lay the 1 layer of 4# large surface obtained in step 1 in the female mold of the helmet paving mold as the outermost layer, and then lay 2 layers of 3# small surfaces, 2 layers of 1# large surfaces and 2 sheets of 2# small surfaces in sequence on the outermost layer 4# large surface corresponding to the center of the helmet paving mold, wherein the 2 layers of 3# small surfaces are completely overlapped, the 2 layers of 1# large surfaces are completely overlapped and the seams are overlapped, the vertices of the sunken triangular notches in the 2 sheets of 2# small surfaces are successively connected in the same direction to the 2 symmetrical overlapping seams of the 2 layers of 1# large surfaces, and half of each 2# small surface is overlapped on the upper surface of the 2 layers of 1# large surfaces, and the other half is overlapped on The lower surface of the 2-layer 1# large surface forms a clamping structure, and then 2-layer 3# small surface is laid in sequence on the clamping structure corresponding to the center of the helmet paving mold, and the 2-layer 3# small surface is completely overlapped to obtain a paving unit consisting of 2-layer 3# small surface, 2-layer 1# large surface, 2 sheets of 2# small surface and 2-layer 3# small surface, and the above-mentioned process of laying 2-layer 3# small surface, 2-layer 1# large surface and 2 sheets of 2# small surface, and 2-layer 3# small surface is repeated in sequence until several paving units are obtained, and 1-layer 4# large surface is laid as the innermost layer on the last 2-layer 3# small surface laid in the last paving unit to obtain a helmet shell paving body;

[0018] The first large surface of each layer in the plurality of paving units is tailor-made to coincide with the fourth large surface of the outermost layer and the fourth large surface of the innermost layer, and the right angle portion of the square in the first large surface of each layer that is independent of the 3 / 4 area circle is aligned with the right angle portion of the fourth large surface of the outermost layer and the fourth large surface of the innermost layer;

[0019] Step 3: Preheating and forming: The helmet shell obtained in step 2 is mounted on the male mold of the preheating forming mold and pressed until it is completely fitted. The male mold is then pressed against the female mold and preheated to form the helmet shell. The female mold is then raised and the preformed helmet shell is removed from the male mold.

[0020] Step 4: Hot pressing: placing the preformed helmet shell taken out in step 3 into an open mold of a hydraulic press for hot pressing to obtain a hot pressed helmet shell;

[0021] Step 5: Hot pressing and cooling: The hot-pressed helmet shell obtained in step 4 is placed in an open mold of a hydraulic press for hot pressing, and then cooling water is switched to cool the mold until the mold temperature drops to room temperature. The helmet shell blank is then taken out of the mold to obtain the helmet shell blank;

[0022] Step 6: Edge cutting and punching: Place the helmet shell blank obtained in step 5 on the mold in the laser cutting machine for edge cutting and punching;

[0023] Step 7: Adhere the edge sealing strips: Grind the helmet shell blank after trimming and punching in step 6 and remove dirt, then apply glue on both sides of the edge of the helmet shell blank and adhere the strips;

[0024] Step 8: Internal and external surface treatment: clean the dirt and attachments on the internal and external surfaces of the helmet shell blank that has been sealed with edge strips in step 7;

[0025] Step 9, spraying polyurea: spraying polyurea on the helmet shell blank after the internal and external surface treatment in step 8, forming a polyurea paint film on the surface of the helmet shell blank to obtain a helmet shell;

[0026] Step 10: Assemble the suspension system and the helmet cover: Install the suspension system in the helmet shell obtained in step 9, and then install the helmet cover on the surface of the helmet shell to obtain a PE bulletproof helmet.

[0027] The present invention first conducts a lofting design based on the structure and performance of the target product, a PE bulletproof helmet. Then, using biorthogonal PEUD prepreg and PE plain weave prepreg fabric as raw materials, they are cut to obtain 1# large surface, 2# small surface, 3# small surface, and 4# large surface of different shapes and structures. Each fabric is then layered in a mold to prepare a helmet shell paving body. The body is then sequentially subjected to preheating molding, hot pressing molding, hot pressing and cooling molding, trimming and punching, gluing edge sealing strips, internal and external surface treatment, polyurea spraying, assembly of a suspension system, and a cap cover to obtain a PE bulletproof helmet. Ultimately, the PE bulletproof helmet prepared by the present invention includes a helmet shell, a paint layer, and a suspension component. The helmet shell includes an inner layer, an intermediate layer, and an outer layer. The intermediate layer is made of biorthogonal PEUD prepreg, and both the inner and outer layers are made of PE plain weave prepreg fabric.

[0028] In the preparation process of the present invention, firstly, a multi-layer bi-orthogonal PEUD prepreg is selected as the main structural material of the helmet shell in the helmet, and the characteristics of the bi-orthogonal PEUD prepreg that does not have bending yarns and has a larger impact energy transmission range, more absorption, and a higher ballistic limit are utilized, so that the helmet shell forms a hard plate structure, which is beneficial to improving the bending strength and inward deformation resistance of the helmet shell, reducing the possibility of blunt injuries, and improving the protectiveness of the PE bulletproof helmet. At the same time, PE plain prepreg fabric is used as the outer layer and inner layer of the helmet shell, i.e., the surface cloth, to effectively protect the PEUD main structure of the helmet shell, facilitate subsequent spraying of polyurea, and ensure that the surface of the PE bulletproof helmet is smooth and has a good wearing feel.

[0029] Secondly, when a bullet impacts a PE helmet, the impact often occurs within a few microseconds, leaving the impact stress too late to diffuse through the PEUD material. Furthermore, after ballistic penetration, the PEUD material's layers are distributed in a conical pattern along the thickness, with less damage to the impact surface and more severe damage to the back surface. Research has found that when a bullet impacts a PE helmet, the penetration energy of a high-speed projectile, such as a bullet, propagates and dissipates through the PEUD material in the form of two stress waves: transverse and longitudinal. The longitudinal stress wave originates from the impact point, propagates outward along the fiber axis of the PEUD material, and propagates through the gaps between the fiber and the matrix resin, generating tensile strain. Subsequently, under the continued penetration of the projectile, the PEUD material in the PE helmet undergoes lateral displacement and forms a conical deformation region through the thickness. This process dissipates energy through deformation aging of the PEUD material and the matrix, interfacial damage caused by deformation mismatch, and friction between the fiber and matrix. Subsequently, the local PEUD material in contact with the bullet fractures and fails, forming a perforation, and the ballistic impact stress wave propagates through the material's thickness. Therefore, during the entire ballistic impact process, the kinetic energy carried by the projectile is gradually converted into strain energy of the PEUD fibers and matrix in the PEUD helmet shell, and is absorbed and diffused in the form of material strain failure, thereby resisting the penetrating damage caused by the projectile impact, ensuring that the PEUD helmet shell is not penetrated by the projectile and the projectile dent size is smaller.

[0030] Therefore, the present invention designs the shape and laying method of each surface layer in the helmet shell paving body, and adopts 4# large surface as the outermost layer and innermost layer of the helmet shell paving body as the surface cloth, which ensures that the surface of the PE bulletproof helmet is smooth and the three-dimensional sense is stronger, and is conducive to the subsequent polyurea spraying film formation, and then adopts a paving unit composed of 2 layers of 3# small surface, 2 layers of 1# large surface, 2 sheets of 2# small surface and 2 layers of 3# small surface for circular paving. In this paving unit, 2 layers of 1# large surface are used as the main structure of the helmet shell, which ensures the overall protective performance of the helmet shell, and 2 layers of 3# small surface are laid on the lower and upper parts of the 1# large surface to play a local reinforcement role to ensure the rigidity of the top of the helmet shell, thereby improving the bulletproof performance of the top of the helmet shell. The ability to achieve this by sequentially and symmetrically attaching two 2# small facets to the two symmetrically overlapping seams of the 2# layer 1# large facets in the same direction, with half of each 2# small facet overlapping the upper surface of the 2# layer 1# large facets and the other half overlapping the lower surface of the 2# layer 1# large facets, forming a snap-fit structure. This not only improves the overlapping stability of the two 1# large facets, but also effectively absorbs the impact force from the side of the 1# large facets, greatly enhancing the lateral rigidity of the helmet shell. The impact stress wave in the thickness direction of the helmet shell is transmitted to the circumference of the PEUD material, where it absorbs and diffuses, effectively resisting penetration damage caused by projectile impact, preventing the PE bulletproof helmet from being penetrated by projectiles or reducing the size of projectile indentations, thereby improving the protective performance of the PE bulletproof helmet. At the same time, by ensuring that the right angles of the 1# large facets in each paving unit are aligned with the right angles of the 4# large facets, the directionality of the helmet shell's brim and earmuffs is ensured. Through the above combined effects, the present invention provides a lightweight, high-protection PE bulletproof helmet.

[0031] Furthermore, during the preparation of the helmet shell paving body of the present invention, a snap-fit structure formed by two layers of 1# large facets and two sheets of 2# small facets is designed in the paving unit. This allows the overlapping portions of the two 2# small facets' bi-orthogonal PEUD prepregs and the two 1# large facets' bi-orthogonal PEUD prepregs to be closely arranged along the circumference of the helmet shell and combined with the upper and lower layers of 3# small facets. This ensures that the overlapping portions along the circumference of the helmet shell are uniform and effective, and the relative number of layers is consistent, resulting in a wrinkle-free helmet shell surface and improving the stability and consistency of the PE bulletproof helmet's ballistic and fragment protection performance at a random point on the helmet shell. Furthermore, because the bi-orthogonal PEUD prepreg and the PE plain weave prepreg fabric in the helmet shell paving body are laid at different angles during the laying process, this helps reduce fiber curvature, increases the propagation speed of impact stress waves in the fibers, and thus improves the fiber's energy absorption, thereby further improving the protective performance of the PE bulletproof helmet.

[0032] Again, the present invention adopts dual orthogonal PEUD prepreg and PE plain prepreg fabric as raw materials, designs the cutting and layout method, and combines the laying method of the helmet shell paving body to ensure the orthogonal fiber structure in the helmet shell paving body, and the fibers are arranged parallel to each other in the subsequent heating molding process. Combined with the fiber bending and interweaving gripping effect in the fabric, it is beneficial for the shock stress wave generated during the bullet impact to propagate along the axial direction of the PE bulletproof helmet fiber, thereby increasing the number of fibers that effectively bear the shock stress wave, which is more conducive to improving the diffusion speed of the shock stress wave and further improving the protective performance of the PE bulletproof helmet.

[0033] The present invention utilizes a sequential preheating, hot pressing, and hot pressing and cooling processes to fully melt and bond the resins in the bi-orthogonal PEUD prepreg and PE plain weave prepreg fabric in the helmet shell body, ensuring smooth helmet shell formation. In particular, the present invention employs hot pressing and cooling processes after hot pressing, allowing for rapid cooling after heating and hot pressing, improving the molding performance of the bi-orthogonal PEUD prepreg.

[0034] The above-mentioned method for forming a lightweight, high-protection PE bulletproof helmet is characterized in that the radius of the 3 / 4 area circle in the 1# large surface in step 1 is 260mm, and the length of the four tailorings is 190mm; the diameter of the semicircle in the 2# small surface is 245mm, the length of the base of the indented triangular notch is 30mm, and the length of the two hypotenuses is 25mm; the diameter of the circle in the 3# small surface is 245mm; the side length of the square in the 4# large surface is 486mm, and the length of the four tailorings is 170mm. By controlling the size of each fabric in the helmet shell paving body, the present invention effectively controls the size of the PE bulletproof helmet, meets standard requirements, and simultaneously achieves lightweight PE bulletproof helmets and saves raw material costs.

[0035] The aforementioned method for forming a lightweight, high-protection PE bulletproof helmet is characterized in that the number of the plurality of paving units in step 2 is 17. The molding method of the present invention greatly improves the protective performance of the PE bulletproof helmet. The present invention can produce a high-protection PE bulletproof helmet using only 17 paving units, further saving raw material costs.

[0036] The above-mentioned method for forming a lightweight high-protection PE bulletproof helmet is characterized in that the preheating and forming pressure in step 3 is 10kg / cm 2 ~20kg / cm 2 The temperature of the male mold is 50℃, the temperature of the female mold is 60℃, and the time is 1min~2min.

[0037] The above-mentioned method for forming a lightweight high-protection PE bulletproof helmet is characterized in that the hot pressing process in step 4 is: using electric heating, the male mold is at the bottom and the female mold is at the top during the hot pressing process, and the hot pressing pressure is 100kg / cm 2 ~110kg / cm 2 The temperature of the male mold is 120℃, the temperature of the female mold is 130℃, the time is 10min, and when the hot pressing molding is 5min~7min, the female mold is raised to exhaust three times, each time with an interval of 1min, and the exhaust time is 10s. When the hot pressing molding is completed, the female mold is raised and the hot pressed helmet shell is taken out from the male mold.

[0038] The above-mentioned method for forming a lightweight high-protection PE bulletproof helmet is characterized in that the hot pressing and cooling process in step 5 is as follows: during the hot pressing process, the male mold is at the bottom and the female mold is at the top, and the hot pressing pressure is 140kg / cm 2 ~150kg / cm 2 The temperature of the male mold is 125℃, the temperature of the female mold is 130℃, the time is 15 minutes, then keep the pressure unchanged, switch the cooling water to circulate the mold for 10 minutes to 20 minutes.

[0039] The aforementioned method for forming a lightweight, highly protective PE bulletproof helmet is characterized in that the spraying temperature in step nine is 80°C, the pressure is 1400 psi, the number of spraying cycles is 5, and the speed is 6 rpm; the width of the polyurea paint film is 10 mm, and the thickness is 0.5 mm to 0.8 mm. The polyurea material used in the present invention has excellent corrosion resistance, anti-fragmentation, and explosion-proof properties, not only protecting the helmet but also helping to improve its protective performance. Simultaneously, by controlling the spraying process parameters including temperature, pressure, number of cycles, and speed, the spraying quality is effectively improved, resulting in a polyurea paint film with a smooth surface, uniform thickness, and close adhesion to the helmet shell. By controlling the width and thickness of the polyurea paint film, the weight of the helmet is further reduced, achieving lightweight performance.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] 1. The present invention adopts multi-layer bi-orthogonal PEUD prepreg with excellent energy absorption and impact resistance as the main structural material of the helmet shell, which is beneficial to improving the bending strength and resistance to inward deformation of the helmet shell, reducing the possibility of blunt injuries, and improving the protectiveness of the PE bulletproof helmet. At the same time, PE plain prepreg fabric is used as the surface fabric of the helmet shell, which effectively protects the PEUD main structure of the helmet shell, makes the surface of the PE bulletproof helmet smooth, and has a good wearing feel, while achieving the lightweight of the PE bulletproof helmet.

[0042] 2. The present invention designs the shape and laying method of each surface layer in the helmet shell paving body. By laying two layers of 3# small surfaces on the upper and lower surfaces of the two layers of 1# large surface of the main structure in the paving unit for local reinforcement, the rigidity of the top of the helmet shell is ensured, and the bulletproof capability of the top of the helmet shell is improved. The two 2# small surfaces and the two layers of 1# large surface form a snap-fit structure, which greatly enhances the lateral rigidity of the helmet shell, thereby improving the protective performance of the PE bulletproof helmet.

[0043] 3. The present invention designs a snap-fit structure formed by two layers of 1# large surface and two 2# small surface in the laying unit, so that the overlapping parts of the dual-orthogonal PEUD prepreg are arranged closely with each other along the circumference path of the helmet shell, ensuring that the overlapping parts along the circumference direction of the helmet shell are uniform and effective and the relative number of layers is consistent, so that the surface of the helmet shell is wrinkle-free, and the stability and consistency of the ballistic performance and anti-fragmentation performance of the PE bulletproof helmet at a random point on the helmet shell are improved.

[0044] 4. The laying angles of the dual-orthogonal PEUD prepreg and the PE plain prepreg fabric in the helmet shell paving body of the present invention are different, which reduces the curvature of the fiber and increases the propagation speed of the impact stress wave in the fiber, that is, improves the energy absorption effect of the fiber, and further improves the protective performance of the PE bulletproof helmet.

[0045] 5. The present invention adopts dual-orthogonal PEUD prepreg and PE plain prepreg fabric as raw materials, combined with cutting layout and laying methods, to ensure the orthogonal fiber structure in the helmet shell paving body, as well as the fiber buckling and interweaving gripping effect in the fabric, which is beneficial to increase the number of fibers that effectively bear the impact stress wave and improve the diffusion speed of the impact stress wave, further improving the protective performance of the PE bulletproof helmet.

[0046] 6. The present invention designs a cutting and layout method for the surface materials in the helmet shell paving body, which maximizes the use of raw materials and avoids waste of raw materials. The cutting accuracy of the CNC cutting machine is higher, and at the same time, it ensures that each surface material of the same shape is interchangeable.

[0047] 7. The present invention performs hot pressing cooling molding after hot pressing molding. By rapidly cooling after heating and hot pressing, the double orthogonal PEUD prepreg in the helmet shell paving body is promoted to fully melt-bond, thereby improving the molding effect of the double orthogonal PEUD prepreg.

[0048] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a flowchart of the PE bulletproof helmet molding method and subsequent testing and packaging of the present invention.

[0050] Figure 2a This is a structural diagram of the 1# large surface in Example 1 of the present invention.

[0051] Figure 2b This is a schematic structural diagram of the 2# small surface in Example 1 of the present invention.

[0052] Figure 2c This is a schematic structural diagram of the 3# small surface in Example 1 of the present invention.

[0053] Figure 2d This is a schematic structural diagram of the 4# large surface in Example 1 of the present invention.

[0054] Figure 3 Schematic diagram of the basic structure of the bi-orthogonal PEUD prepreg used in Example 1 of the present invention.

[0055] Figure 4 This is a cutting layout diagram of the biorthogonal PEUD prepreg in Example 1 of the present invention.

[0056] Figure 5 This is a cutting layout diagram of the PE plain weave prepreg fabric in Example 1 of the present invention.

[0057] Figure 6 This is a schematic diagram of the clamping structure formed by two 2# small surfaces and two layers of 1# large surfaces in Example 1 of the present invention.

[0058] Figure 7a This is a schematic diagram of the top structure of the PE bulletproof helmet prepared in Example 1 of the present invention.

[0059] Figure 7b for Figure 7a AA view in.

[0060] Figure 7c This is a schematic diagram of the front structure of the PE bulletproof helmet prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0061] Example 1

[0062] like Figure 1 As shown, the PE bulletproof helmet molding method of this embodiment includes the following steps:

[0063] Step 1: Lofting design and cutting: Lofting design is performed on the target product PE bulletproof helmet to obtain the following Figure 2aAs shown in the 1# large surface, the shape of the 1# large surface is a combination of a 3 / 4 area circle and a square with a side length equal to the radius of the 3 / 4 area circle, and the two outer radii of the 3 / 4 area circle completely coincide with the two adjacent sides of the square. In the 1# large surface, along the two sides where the 3 / 4 area circle coincides with the square and the direction of the extension line, four seams are opened from the circumference to the center of the circle, and the lengths of the four seams are all equal and less than the radius of the 3 / 4 area circle in the 1# large surface. The radius of the 3 / 4 area circle is 260mm, and the lengths of the four seams are all 190mm. Figure 2b The 2# small face shown is a semicircle with an indented triangular notch at the center. The diameter of the semicircle is 245mm. The bottom edge of the indented triangular notch coincides with the diameter of the semicircle. The length of the bottom edge of the indented triangular notch is 30mm, and the length of the two oblique sides is 25mm. Figure 2c The 3# small face shown is circular, and the diameter of the circle is 245mm. Figure 2d The 4# large surface shown is a square, and in the 4# large surface, there are four tailorings in the direction perpendicular to the four sides of the square from the four sides to the center of the square, and the lengths of the four tailorings are equal and less than half the side length of the 4# large surface. The side length of the square in the 4# large surface is 486mm, and the length of the four tailorings is 170mm.

[0064] Then according to the design results, the basic structure is cut by CNC cutting machine. Figure 3 The double orthogonal PEUD prepreg with one side impregnated with phenolic resin glue is cut. The specific cutting and layout method is as follows Figure 4 As shown in the figure, the size of the selected single-sided double-orthogonal PEUD prepreg with phenolic resin adhesive is 2100mm×1400mm in length×width, and 8 1# large faces, 5 2# small faces and 8 3# small faces are obtained; the PE plain weave prepreg fabric is cut by a CNC cutting machine, and the specific cutting layout method is as follows Figure 5 As shown, the size of the selected single PE plain weave prepreg fabric is 1480mm×1000mm in length and width, and 6 4# large surfaces are obtained;

[0065] It should be noted that during the cutting process of this embodiment, the cloth should be laid out with one side aligned, and the cutting order should be based on cutting the small pieces first. The cutting should be strictly along the line to prevent the knife from slipping and uneven cutting lines. The cutting should be carried out according to the number of layers and structural design of the subsequent helmet shell paving body to obtain a sufficient number of 1# large surface, 2# small surface, 3# small surface, and 4# large surface, and the number of layers should be marked on the 1# large surface, 2# small surface, 3# small surface, and 4# large surface respectively.

[0066] Step 2, prepare the helmet shell paving body: lay the 1 layer of 4# large surface obtained in step 1 in the female mold of the helmet paving mold as the outermost layer, and then lay 2 layers of 3# small surface, 2 layers of 1# large surface and 2 sheets of 2# small surface in sequence on the outermost layer 4# large surface corresponding to the center of the helmet paving mold, wherein the 2 layers of 3# small surface are completely overlapped, the 2 layers of 1# large surface are completely overlapped and the seams are overlapped, the vertices of the sunken triangular notches in the 2 sheets of 2# small surface are successively clamped in the same direction on the 2 symmetrical overlapping seams of the 2 layers of 1# large surface, and half of each 2# small surface is overlapped on the upper surface of the 2 layers of 1# large surface, and the other half is overlapped on the lower surface of the 2 layers of 1# large surface to form a clamping structure, such as Figure 6 As shown, Figure 6 The grey solid line and grey dotted line in the figure represent half of the 2# small surface stacked on the upper surface and lower surface of the 2 layers of 1# large surface, respectively. Then, 2 layers of 3# small surfaces are laid in sequence at the center of the corresponding helmet laying mold on the snap-fit structure, and the 2 layers of 3# small surfaces are completely overlapped to obtain a laying unit consisting of 2 layers of 3# small surfaces, 2 layers of 1# large surface, 2 sheets of 2# small surfaces and 2 layers of 3# small surfaces. The above process of laying 2 layers of 3# small surfaces, 2 layers of 1# large surface and 2 sheets of 2# small surfaces, and 2 layers of 3# small surfaces is repeated in sequence until 17 laying units are obtained, and 1 layer of 4# large surface is laid as the innermost layer on the last 2 layers of 3# small surfaces laid in the last paving unit to obtain a helmet shell paving body.

[0067] The first large surface of each layer in the 17 paving units is tailor-made to coincide with the fourth large surface of the outermost layer and the fourth large surface of the innermost layer, and the right angles of the squares in the first large surface of each layer that are independent of the 3 / 4 area circle are aligned with the right angles of the fourth large surface of the outermost layer and the fourth large surface of the innermost layer;

[0068] It should be noted that the overlapping of each surface layer should be carried out in the order of the layer number markings, and it is not allowed to be reversed. The overlapping stretching should be moderate, the front, back, left and right positioning should be accurate, and the overlapping of each layer in the laid helmet shell prefabricated body should be tight, firmly bonded and not loose, and smooth, without wrinkles, looseness or delamination. When removing the helmet after laying, it should be opened carefully from the bottom up with tools, and it should not be directly buckled from the inside out by hand, so as to avoid causing the helmet opening to be too large and unable to be pre-pressed. The helmet shell paving body should be handled with care, covered and stored away from light and moisture to prevent the helmet body from scattering; prevent water and dust from falling in.

[0069] Step 3, preheating and molding: install the helmet shell paving body obtained in step 2 on the male mold of the preheating molding mold, and the brim of the helmet shell paving body fits on the brim position of the male mold of the preheating molding mold, and press the top of the helmet shell paving body with your hand to apply downward pressure so that the helmet shell paving body is completely fitted on the male mold of the preheating molding mold, and then open the reversing valve to make the female mold of the preheating molding mold descend and press the male mold tightly, ensuring that the pressure is 10kg / cm 2 ~20kg / cm 2, and heat the male mold to 50°C and the female mold to 60°C, and keep them warm for 1min~2min. After the shaping is completed, lift the female mold and take the preformed helmet shell out from the male mold. Weigh the preformed helmet shell to obtain a weight of 1.0kg~1.2kg;

[0070] Step 4: Hot pressing: Place the preformed helmet shell taken out in step 3 into the open mold of the hydraulic press for hot pressing. Electric heating is used. During the hot pressing process, the male mold is at the bottom and the female mold is at the top. The hot pressing pressure is 100kg / cm 2 ~110kg / cm 2 The temperature of the male mold is 120℃, the temperature of the female mold is 130℃, the time is 10min, and when the hot pressing molding is 5min~7min, the female mold is raised to exhaust three times, each interval is 1min, and the exhaust time is 10s. When the hot pressing molding is completed, the female mold is raised and taken out from the male mold to obtain the hot pressing molded helmet shell;

[0071] Step 5: Hot pressing and cooling: Place the hot pressed helmet shell obtained in step 4 into the open mold of a hydraulic press for hot pressing. During the hot pressing process, the male mold is at the bottom and the female mold is at the top. The hot pressing pressure is 140 kg / cm 2 ~150kg / cm 2 The temperature of the male mold is 125℃, and the temperature of the female mold is 130℃ for 15 minutes. Then, the pressure is kept constant and the cooling water is switched to circulate the mold for 10 to 20 minutes until the mold temperature drops to room temperature. The helmet shell blank is taken out from the male mold of the mold.

[0072] It should be noted that the helmet shell blank should be compacted without wrinkles, peeling or blistering, and the appearance of the helmet shell blank should be symmetrical and the helmet body should be full.

[0073] Step 6: Trimming and punching: Place the helmet shell obtained in step 5 on a mold in a laser cutting machine for edge cutting and punching, and weigh it to obtain a weight of 0.7kg to 0.8kg;

[0074] It should be noted that during the cutting process, the laser beam of the laser cutting machine cuts the flash along the edge line of the helmet shell blank, and the cutting is neat and burr-free. The cut edge should be straight, the incision should be flat, the edge should be neat and straight, the arc should be smooth, and there should be no deviation, gaps, virtual edges, or missing layers or meat. When punching, the hole position is determined according to customer requirements, usually 4 holes, two on each side, with a hole diameter of 5.5mm. The left and right holes are required to be symmetrical and not skewed, and the burrs on the hole mouth should be cut cleanly.

[0075] Step 7, sticking edge sealing strips: Use sandpaper to polish the helmet opening of the helmet shell blank after trimming and punching in step 6 and the place where the strips are to be bonded. After polishing, there are no scratches or overflows on the surface, and the flash is clean. Use a high-pressure air gun to blow away the attached dirt on the inner and outer surfaces of the helmet shell blank. Then, evenly apply 101 glue on both sides of the edge of the helmet shell blank and stick the neoprene strips. Ensure that the appearance of the strips is smooth and the transition between the straight line and the arc is natural and smooth. The two ends of the strips overlap by 10mm at the edge of the helmet shell blank.

[0076] It should be noted that after bonding, the neoprene rubber strips should not have cracks, false adhesion, wrinkles, deflections, virtual edges, or unevenness, and the neoprene rubber strips should be firmly bonded to the helmet shell, with natural straight arc transitions and consistent width.

[0077] Step 8: Internal and external surface treatment: Use alcohol cotton yarn to remove fine dirt and other attached contaminants on the internal and external surfaces of the helmet shell blank that has been sealed with edge strips in step 7, ensuring that there is no oil, water, silicone oil or other paint mist attached to the internal and external surfaces of the helmet shell blank, and the surface is smooth. Then use a high-pressure air gun to blow away the attached dirt on the internal and external surfaces of the helmet shell blank;

[0078] Step 9: Spraying polyurea: Using a dedicated polyurea spraying device, spray polyurea onto the helmet shell blank after the internal and external surface treatment in Step 8. The spraying temperature is 80°C, the pressure is 1400 psi, the number of spraying cycles is 5, and the speed is 6 rpm. The polyurea paint film with high strength and high elasticity, a width of 10 mm, and a thickness of 0.5 mm to 0.8 mm is rapidly solidified on the surface of the helmet shell blank to obtain a helmet shell.

[0079] It should be noted that the paint surface should be even during spraying, without any paint leakage, paint flow, or air holes, and the paint surface on the inner surface of the helmet shell should be flat and smooth.

[0080] Step 10. Assemble the suspension system and the helmet cover: Use 4 M5 hexagon socket screws to install the suspension system in the helmet shell obtained in step 9. Note that the front and rear positions of the suspension system are consistent with the helmet shell. Tighten the nuts, then install the helmet cover on the surface of the helmet shell, and ensure that the helmet cover is flat and smooth on the surface of the helmet shell without wrinkles. Then you will get a PE bulletproof helmet. Figure 7a to Figure 7c shown.

[0081] The prepared PE bulletproof helmets are inspected, tested and packaged, and the specific process is: inspect and confirm that the PE bulletproof helmet is complete and clean and dry; fasten the emergency release buckle of the PE bulletproof helmet after passing the inspection, adjust the head circumference adjuster to the maximum, and then put the product certificate, product use and maintenance instructions, and desiccant into the helmet, wrap them with copy paper, put them into a polyethylene plastic bag, and seal them; put them sideways into the inner packaging box in a stack of 5, and then put the two inner packaging boxes into the outer packaging box, and put the "Packaging Inspection Sheet" on the upper part of the box; use polypropylene plastic strapping tape to tighten the outer packaging box in a crisscross direction, requiring it to be straight, firm, and moderately tight; add a layer of polypropylene plastic woven cloth to the outside of the carton for reinforced packaging.

[0082] After testing, the PE bulletproof helmet prepared in this embodiment meets the requirements of GA293-2012 "Police Bulletproof Helmets and Face Masks", WHB901-2015 "15 Armed Police General Helmets Manufacturing and Acceptance Technical Conditions" and GJB5115A-2012 "Safety Technical Performance Requirements for Military Bulletproof Helmets", which stipulate that the weight of the finished L-size bulletproof helmet (including the helmet cover) shall not exceed 1300g, indicating that the PE bulletproof helmet has excellent lightweight performance.

[0083] According to GA293-2012 "Police Bulletproof Helmets and Masks", WHB901-2015 "15 Armed Police General Helmets Manufacturing and Acceptance Technical Conditions" and GJB5115A-2012 "Safety Technical Performance Requirements for Military Bulletproof Helmets", the PE bulletproof helmet prepared in this embodiment was subjected to a shooting test, and the results are shown in Table 2 below.

[0084] Table 2

[0085]

[0086] The size of the helmet dent is a direct standard for measuring the bulletproof performance of the helmet and an important indicator for measuring the quality of the helmet. Because a large dent in the helmet caused by bullets will cause secondary damage to the human head and directly threaten life and health, the helmet dent is an important indicator for measuring the quality of the helmet.

[0087] As can be seen from Table 2, the PE bulletproof helmet prepared in this embodiment is not penetrated when shooting from different shooting positions including the top, front, left, right and back of the helmet. At the same time, under the premise that the PE bulletproof helmet is not penetrated, the bullet mark height, i.e., the depression, at each shooting position of the PE bulletproof helmet is significantly reduced compared with the 25mm requirement in the standard, indicating that the PE bulletproof helmet is not only highly bulletproof, but also effectively avoids secondary damage to the human head caused by shooting depressions, and has excellent protective performance.

[0088] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for forming a lightweight, high-protection PE bulletproof helmet, characterized in that: The method comprises the following steps: Step 1: Lofting design and cutting: Perform lofting design on the target product, PE bulletproof helmet, and then cut the bi-orthogonal PEUD prepreg according to the design results to obtain 1# large surface, 2# small surface and 3# small surface, and cut the PE plain weave prepreg fabric to obtain 4# large surface; The shape of the 1# large surface is a combination of a 3 / 4 area circle and a square with a side length equal to the radius of the 3 / 4 area circle, and the two outer radii of the 3 / 4 area circle completely coincide with two adjacent sides of the square. In the 1# large surface, four seams are opened in sequence from the circumference to the center of the circle along the two sides and the extension line where the 3 / 4 area circle coincides with the square, and the lengths of the four seams are all equal and less than the radius of the 3 / 4 area circle in the 1# large surface; The 2# small face is a semicircle with an indented triangular notch at the center, and the bottom edge of the indented triangular notch coincides with the diameter of the semicircle; The 3# small face is circular; The 4# large surface is a square, and the 4# large surface has 4 tailorings in the direction perpendicular to the four sides of the square from the four sides to the center of the square, and the lengths of the 4 tailorings are equal and less than half the side length of the 4# large surface; Step 2, prepare the helmet shell paving body: lay the 1 layer of 4# large surface obtained in step 1 in the female mold of the helmet paving mold as the outermost layer, and then lay 2 layers of 3# small surfaces, 2 layers of 1# large surfaces and 2 sheets of 2# small surfaces in sequence on the outermost layer 4# large surface corresponding to the center of the helmet paving mold, wherein the 2 layers of 3# small surfaces are completely overlapped, the 2 layers of 1# large surfaces are completely overlapped and the seams are overlapped, the vertices of the sunken triangular notches in the 2 sheets of 2# small surfaces are successively connected in the same direction to the 2 symmetrical overlapping seams of the 2 layers of 1# large surfaces, and half of each 2# small surface is overlapped on the upper surface of the 2 layers of 1# large surfaces, and the other half is overlapped on The lower surface of the 2-layer 1# large surface forms a clamping structure, and then 2-layer 3# small surface is laid in sequence on the clamping structure corresponding to the center of the helmet paving mold, and the 2-layer 3# small surface is completely overlapped to obtain a paving unit consisting of 2-layer 3# small surface, 2-layer 1# large surface, 2 sheets of 2# small surface and 2-layer 3# small surface, and the above-mentioned process of laying 2-layer 3# small surface, 2-layer 1# large surface and 2 sheets of 2# small surface, and 2-layer 3# small surface is repeated in sequence until several paving units are obtained, and 1-layer 4# large surface is laid as the innermost layer on the last 2-layer 3# small surface laid in the last paving unit to obtain a helmet shell paving body; The first large surface of each layer in the plurality of paving units is tailor-made to coincide with the fourth large surface of the outermost layer and the fourth large surface of the innermost layer, and the right angle portion of the square in the first large surface of each layer that is independent of the 3 / 4 area circle is aligned with the right angle portion of the fourth large surface of the outermost layer and the fourth large surface of the innermost layer; Step 3: Preheating and forming: The helmet shell obtained in step 2 is mounted on the male mold of the preheating forming mold and pressed until it is completely fitted. The male mold is then pressed against the female mold and preheated to form the helmet shell. The female mold is then raised and the preformed helmet shell is removed from the male mold. Step 4: Hot pressing: placing the preformed helmet shell taken out in step 3 into an open mold of a hydraulic press for hot pressing to obtain a hot pressed helmet shell; Step 5: Hot pressing and cooling: The hot-pressed helmet shell obtained in step 4 is placed in an open mold of a hydraulic press for hot pressing, and then cooling water is switched to cool the mold until the mold temperature drops to room temperature. The helmet shell blank is then taken out of the mold to obtain the helmet shell blank; Step 6: Edge cutting and punching: Place the helmet shell blank obtained in step 5 on the mold in the laser cutting machine for edge cutting and punching; Step 7: Adhere the edge sealing strips: Grind the helmet shell blank after trimming and punching in step 6 and remove dirt, then apply glue on both sides of the edge of the helmet shell blank and adhere the strips; Step 8: Internal and external surface treatment: clean the dirt and attachments on the internal and external surfaces of the helmet shell blank that has been sealed with edge strips in step 7; Step 9, spraying polyurea: spraying polyurea on the helmet shell blank after the internal and external surface treatment in step 8, forming a polyurea paint film on the surface of the helmet shell blank to obtain a helmet shell; Step 10: Assemble the suspension system and the helmet cover: Install the suspension system in the helmet shell obtained in step 9, and then install the helmet cover on the surface of the helmet shell to obtain a PE bulletproof helmet.

2. The method for forming a lightweight high-protection PE bulletproof helmet according to claim 1, characterized in that: The radius of the 3 / 4 area circle in the 1# large surface in step 1 is 260mm, and the length of the four tailors is 190mm; the diameter of the semicircle in the 2# small surface is 245mm, and the length of the bottom side of the sunken triangle notch is 30mm, and the length of the two oblique sides is 25mm; the diameter of the circle in the 3# small surface is 245mm; the side length of the square in the 4# large surface is 486mm, and the length of the four tailorings is 170mm.

3. The molding method of a lightweight high-protection PE bulletproof helmet according to claim 1, characterized in that: The number of the plurality of paving units described in step 2 is 17.

4. The method for forming a lightweight high-protection PE bulletproof helmet according to claim 1, characterized in that: The preheating pressure in step 3 is 10 kg / cm 2 ~20kg / cm 2 The temperature of the male mold is 50℃, the temperature of the female mold is 60℃, and the time is 1min~2min.

5. The method for forming a lightweight high-protection PE bulletproof helmet according to claim 1, characterized in that: The hot pressing process in step 4 is as follows: electric heating is used, the male mold is at the bottom and the female mold is at the top, and the pressure of the hot pressing is 100kg / cm 2 ~110kg / cm 2 The temperature of the male mold is 120℃, the temperature of the female mold is 130℃, the time is 10min, and when the hot pressing molding is 5min~7min, the female mold is raised to exhaust three times, each time with an interval of 1min, and the exhaust time is 10s. When the hot pressing molding is completed, the female mold is raised and the hot pressed helmet shell is taken out from the male mold.

6. The method for forming a lightweight high-protection PE bulletproof helmet according to claim 1, characterized in that: The hot pressing and cooling process in step 5 is as follows: the male mold is at the bottom and the female mold is at the top during the hot pressing process, and the hot pressing pressure is 140kg / cm 2 ~150kg / cm 2 The temperature of the male mold is 125℃, the temperature of the female mold is 130℃, the time is 15 minutes, then keep the pressure unchanged, switch the cooling water to circulate the mold for 10 minutes to 20 minutes.

7. The method for forming a lightweight high-protection PE bulletproof helmet according to claim 1, characterized in that: The spraying temperature in step nine is 80° C., the pressure is 1400 psi, the number of spraying circles is 5, and the rotation speed is 6 r / min; the width of the polyurea paint film is 10 mm, and the thickness is 0.5 mm to 0.8 mm.

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