A mold and preparation method for preparing steel wire-FRP composite pipe

Abstract

The present invention relates to a mold and a method for preparing a steel wire-FRP composite pipe, and belongs to the field of FRP composite pipe manufacturing. The mold includes two coaxial end positioning plates spaced apart in the axial direction, a skeleton composed of three or more skeleton slats extending in the transverse direction, and a steel wire mesh formed by spirally winding steel wires around the outside of the skeleton; the end positioning plate includes a plate body and a plurality of slots spaced apart on the outer peripheral wall of the plate body and extending in the radial direction of the plate body; the transverse ends of each skeleton slat are inserted into the corresponding slots of the two end positioning plates. The present invention adopts a steel wire mesh as a mesh profile for fiber winding or wet laying; the skeleton slats are used to form a skeleton with an adjustable shape, which is simple and easy to operate and can meet the shape diversity requirements of FRP composite pipes, that is, FRP composite pipes with various shapes can be prepared according to needs.

Description

Technical Field

[0001] The present application relates to the field of FRP composite pipe manufacturing, and in particular to a mold and a method for preparing a steel wire-FRP composite pipe. Background Art

[0002] FRP pipes are primarily composed of glass fiber and resin. As a corrosion-resistant, lightweight, and high-strength composite pipe, FRP pipes have broad application prospects in chemical engineering, power engineering, marine engineering, construction engineering, road and bridge engineering, and municipal environmental engineering. For example, in the chemical industry, FRP pipes can be used to store or transport corrosive media; in the power industry, they can be used as cable protective sleeves; in marine engineering, they can be used as surface anti-corrosion coatings; in construction and road and bridge engineering, they can also be used as structural components or concrete casting molds; and in municipal environmental engineering, they can be used as landscape molding or water supply and drainage pipelines. Due to its corrosion resistance, light weight, and high strength, FRP pipes have become an indispensable material across various industries, and market demand continues to grow. Pure FRP pipes have a relatively low elastic modulus and are linear elastic materials, resulting in poor ductility. To improve the elastic modulus and ductility of pure FRP pipes, steel wire can be incorporated into the pipe to form a steel wire-FRP composite pipe.

[0003] FRP composite pipes have various shapes and can be customized according to different engineering requirements. FRP composite pipes can be circular, oval, square or even variable cross-section, and can also be combined in sections according to needs. This design with diverse shapes enables FRP composite pipes to meet the use requirements of different scenarios in various engineering fields. One of the keys to the FRP composite pipe manufacturing process is the mold. Currently, circular steel pipe molds are mostly used, and they are mainly for circular FRP pipes. However, for irregular shapes, especially those with variable cross-sections, the production of FRP composite pipes is difficult and costly. This is mainly manifested in the following aspects: for FRP composite pipes with irregular shapes, traditional steel molds are difficult to make and costly, requiring sheet metal, forging, cutting or welding and other steps; demolding is difficult, and molds with complex shapes are difficult to remove; a set of steel molds can only be used for FRP composite pipes of a specific shape, and it is difficult to adapt to the shape diversity requirements of FRP composite pipes. Summary of the Invention

[0004] The purpose of this application is to provide a mold and a method for preparing steel wire-FRP composite pipes, aiming to solve to a certain extent the problem that existing FRP composite pipe preparation molds are difficult to adapt to the requirements of product shape diversity.

[0005] To achieve the above application objectives, the technical solutions adopted in this application are as follows:

[0006] Option 1)

[0007] A mold for preparing a steel wire-FRP composite pipe, comprising two coaxial end positioning plates spaced apart in the axial direction, a frame composed of three or more frame strips extending in the transverse direction, and a steel wire mesh formed by spirally winding steel wire around the frame;

[0008] The end positioning plate includes a plate body and a plurality of slots spaced apart on the outer peripheral wall of the plate body and extending in the radial direction of the plate body;

[0009] The transverse ends of each frame strip are inserted into the corresponding slots of the two end positioning plates.

[0010] Specifically, a plurality of V-shaped teeth are provided on one side of the width direction of the skeleton slat at intervals along the transverse direction; and the included angle of each V-shaped tooth is greater than or equal to 60° and not greater than 120°.

[0011] Specifically, the diameter of the steel wire is not less than 0.8 times the opening width of the V-shaped teeth of the skeleton slats and not greater than the opening width of the V-shaped teeth of the skeleton slats.

[0012] Specifically, the skeleton slats may be straight or curved slats.

[0013] Specifically, the breaking strain of the steel wire is not less than 0.1.

[0014] Specifically, the mold for preparing the steel wire-FRP composite pipe also includes a rotating shaft, a through hole for passing the rotating shaft is provided in the center of the end positioning plate, and a limiting groove connected to the through hole is provided next to the through hole.

[0015] Option 2)

[0016] A method for preparing a steel wire-FRP composite pipe using the mold comprises the following steps:

[0017] S1: Install the two end positioning plates coaxially and spaced correspondingly;

[0018] S2: applying a release agent to the skeleton strips, then respectively installing the skeleton strips coated with the release agent on the slots of the end positioning plates, and adjusting and fixing the positions of the skeleton strips to form the desired skeleton shape according to the shape requirements of the composite pipe to be prepared;

[0019] S3: rotating the frame composed of the frame slats, and spirally winding the steel wire on the frame to form a steel wire mesh;

[0020] S4: Wet-laying or winding the resin-impregnated fibers on the steel wire mesh;

[0021] S5: wait for solidification to obtain the steel wire-FRP composite pipe.

[0022] Specifically, in step S2, when the skeleton strip coated with the release agent is installed on the slot of the end positioning plate, the side with the V-shaped teeth is arranged outward.

[0023] Specifically, in step S4, the angle between the steel wire direction and the fiber direction of the steel wire mesh is not less than 10°.

[0024] Compared to existing technologies, the present invention offers the following advantages: It utilizes a steel mesh as the mesh profile for fiber winding or wet laying; and utilizes slats to form a slatted framework with an adjustable shape, making it simple and easy to operate. Furthermore, it can accommodate the diverse shapes required for FRP composite pipes, which are difficult and costly to manufacture with conventional steel molds. This allows the production of FRP composite pipes in various shapes as needed. The end positioning plates facilitate not only the adjustment and fixation of the slats at the ends but also facilitate demolding and assembly / disassembly.

[0025] The present invention's production method utilizes the end positioning plates and the frame slats to construct frames of varying shapes and sizes. Elastic steel wire is wrapped around the frame to create a relatively smooth mesh profile, replacing the continuous surface profile of conventional molds. Resin-impregnated fibers are then wrapped or wet-laid onto the wire mesh, enabling the production of steel-FRP composite tubes of varying shapes and sizes using a single mold. The wire mesh remains within the steel-FRP composite tube, while the frame slats and end positioning plates are easily removable. This production method directly avoids the challenges of machining, installation, disassembly, and reuse of complex molds. Its flexibility and simplicity make it suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 It is a structural schematic diagram of the mold of Example 1 of the present application (round steel wire-FRP composite pipe).

[0028] Figure 2 It is a structural schematic diagram of the end positioning plate of Example 1 of the present application.

[0029] Figure 3 It is a structural schematic diagram of the skeleton slats of Example 1 of the present application.

[0030] Figure 4This is a schematic diagram of the process of preparing a steel wire-FRP composite pipe according to Example 1 of the present application.

[0031] Figure 5 It is a structural schematic diagram of the mold of Example 2 of the present application (square steel wire-FRP composite tube).

[0032] Figure 6 It is a structural schematic diagram of the mold of Example 3 of the present application (elliptical steel wire-FRP composite tube).

[0033] Figure 7 It is a structural schematic diagram of the mold of Example 4 of the present application (truncated cone-shaped steel wire-FRP composite tube).

[0034] Figure 8 It is a structural schematic diagram of the mold of Example 5 of the present application (hourglass-shaped steel wire-FRP composite pipe).

[0035] Figure 9 This is a schematic structural diagram of the skeleton slats of Example 5 of the present application.

[0036] Among them, the reference numerals in the figures are:

[0037] 1-Skeleton slats; 2-Steel mesh; 3-End positioning plate; 4-Fiber impregnated with resin; 5-Rotating shaft; 6-Rotating bracket; 7-Motor; 8-Steel wire-FRP composite pipe. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0039] In this application, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0040] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0041] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0042] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0043] The term “FRP” is an abbreviation for “Fiber Reinforced Polymer”, which means fiber-reinforced composite material.

[0044] This embodiment provides a mold for preparing a steel wire-FRP composite pipe, such as Figure 1 As shown, it comprises two coaxial end positioning plates 3 spaced apart in the axial direction, a frame composed of three or more frame strips 1 extending in the transverse direction, and a steel mesh 2 formed by spirally winding steel wires around the frame.

[0045] like Figure 2 As shown, the end positioning plate 3 includes a plate body 3-1 and a plurality of slots 3-2 spaced apart on the outer peripheral wall of the plate body 3-1 and extending in the radial direction of the plate body 3-1;

[0046] The transverse ends of each frame slat 1 are inserted into the corresponding slots 3 - 2 of the two end positioning plates 3 .

[0047] The sizes and shapes of the skeleton slats 1, wire mesh 2, and end positioning plates 3 used in the molds for the present invention can be selected from common specifications and can be adjusted based on the desired appearance and mechanical properties of the FRP composite pipe. The number of skeleton slats 1 is no less than 3 and can be 10, 12, or 24. The number of skeleton slats 1 can be increased or decreased as needed. The greater the number of skeleton slats 1, the more complex the skeleton shape can be. However, the number of skeleton slats is not limited herein.

[0048] Traditional mold manufacturing processes require complex processes such as cold bending, sheet metal forming, casting, or welding. First, the wire mesh replaces the traditional mold surface, serving as the mesh profile for fiber winding or wet laying. Steel wire is spirally wound around the framework, supported by the slatted frame, to form the wire mesh. The wire mesh only requires cold bending, making the mold of the present invention relatively simple and feasible.

[0049] Secondly, the skeleton slats are used to form the framework for winding, securing, and supporting the wire mesh. These slats can be produced through laser cutting, eliminating the need for more complex sheet metal processing, bending, casting, or welding, resulting in a simple production method. The thickness of the skeleton slats 1 closely matches the slots 3-2. During installation, the elasticity of the walls on both sides of the slots 3-2 allows for adjustment of the position of the skeleton slats 1 within the slots 3-2.

[0050] Finally, the end positioning plate is used to adjust and fix the position of the skeleton slats at the end. Compared with the clamps of traditional molds, the end positioning plate not only has a fixing function, but also has the function of adjusting the position of the skeleton slats. In addition, a slot is provided to facilitate the installation and fixation of the skeleton slats. By adjusting the middle position of the skeleton slats in the slots of the end positioning plate, skeletons of different shapes can be obtained. The end positioning plate can be obtained by traditional cutting processing methods, and the manufacturing method is simple. The use of the end positioning plate and the skeleton slats of the present invention in combination also facilitates demolding after molding.

[0051] During setting, the end positioning plate is provided with slots and the number of the slots is not less than the number of the skeleton slats, but the number of the slots and the number of the skeleton slats are not limited here.

[0052] In one embodiment, Figure 3 As shown, a plurality of V-shaped teeth 1-1 are provided in the transverse direction on a side wall in a width direction of the skeleton slat 1; the angle of each V-shaped tooth 1-1 is greater than or equal to 60° and not greater than 120°. The angle of each V-shaped tooth 1-1 is not limited here, for example, it can be 60°, 70°, 80°, 90°, 100°, 110° or 120°. The V-shaped teeth 1-1 play a positioning function for the steel wire and can prevent the steel wire from slipping laterally. The arrangement of the tooth groove facilitates the fixation and positioning of the steel wire. The shape of the V-shaped teeth 1-1 facilitates the design and processing of the skeleton slat 1. The smaller the angle of the V-shaped teeth 1-1, the more the smoothness of the wire mesh 2 is affected by the accuracy of the steel wire installation. The larger the angle of the V-shaped teeth 1-1, the more likely the steel wire in the wire mesh 2 is to slip.

[0053] In one embodiment, the steel wire diameter is no less than 0.8 times the opening width of the V-shaped teeth 1-1 of the frame slats and no greater than the opening width of the V-shaped teeth 1-1 of the frame slats. This dimensioning ensures that the V-shaped teeth 1-1 of the frame slats 1 grip the steel wire of the wire mesh 2. This dimensioning effectively prevents the V-shaped teeth 1-1 from protruding beyond the wire mesh 2.

[0054] In one embodiment, the skeleton slats 1 can be straight or curved. The curved slats can be of any shape. The skeleton slats can be obtained by laser cutting, eliminating the need for more complex sheet metal processing, bending, casting, or welding, resulting in a simple production method.

[0055] In one embodiment, the breaking strain of the steel wire is not less than 0.1, so as to avoid the steel wire from being cold-bent and broken during the process of spirally winding the steel wire around the skeleton.

[0056] In one embodiment, the mold for preparing the steel wire-FRP composite pipe also includes a rotating shaft 5, and the center of the end positioning plate 3 is provided with a through hole 3-3 for passing the rotating shaft 5, and a limiting groove 3-4 connected to the through hole 3-3 is provided next to the through hole 3-3.

[0057] A through hole is provided in the center of the end positioning plate for passing the rotating shaft. A limiting groove is also provided next to the through hole, which not only prevents the end positioning plate from axial rotation, but also fixes the relative positions of the two end positioning plates, making it convenient for the subsequent insertion of the skeleton slats.

[0058] like Figure 4 As shown, the steel wire-FRP composite pipe is prepared using the mold of the present invention, including the following steps:

[0059] S1: Install the two end positioning plates 3 coaxially and spaced apart from each other; install the two end positioning plates 3 at both ends of the rotating shaft 5, and then fix the rotating shaft 5 on the rotating bracket 6.

[0060] S2: Apply a release agent to the skeleton strips 1, then install the skeleton strips 1 coated with the release agent on the slots 3-2 of the end positioning plates 3, and adjust and fix the positions of the skeleton strips 1 to form the desired skeleton shape according to the shape requirements of the composite pipe to be prepared;

[0061] S3: rotating the frame composed of the frame slats 1 and spirally winding the steel wires on the frame to form a steel wire mesh 2;

[0062] S4: Wet-laying or winding the resin-impregnated fibers on the steel mesh 2;

[0063] S5: wait for solidification to obtain the steel wire-FRP composite pipe.

[0064] The position of the through slot of the frame strip 1 in the end positioning plate 3 can be determined according to the profile of the steel wire-FRP composite pipe. After determining the position, the two ends of the frame strip 1 are fixed to prevent relative sliding between the frame strip 1 and the end positioning plate 3.

[0065] Specifically, in step S2, when the skeleton strip 1 coated with a release agent is installed on the slot 3-2 of the end positioning plate 3, the side with the V-shaped teeth 1-1 is arranged to face outward.

[0066] Specifically, in step S3, the motor of the rotating bracket drives the rotating shaft to rotate unidirectionally around the axis, and the steel wire is spirally wound around the frame composed of the frame strips 1. Generally, the surface of the steel wire cannot be coated with a release agent to ensure the adhesion between the steel wire and the resin.

[0067] Specifically, in step S4, the steel wire direction and the fiber direction of the steel mesh are not parallel. The specific angle is not less than 10°. Set the angle between the winding direction of the steel wire of the steel mesh 2 and the fiber direction in the FRP composite pipe to be not less than 10°. Only by making the steel wires of the steel mesh 2 and the fiber directions in the fiber bundle or fiber cloth cross each other can the steel wires of the steel mesh 2 be able to support the fibers, thereby ensuring the effective winding or wet laying of the fibers. When performing fiber winding or wet laying operations, the steel mesh 2 can effectively provide support. In addition, the resin effectively bonds the steel wires and fibers, ensuring the strength and rigidity of the FRP composite pipe. After the fiber winding or wet laying operation, continue to rotate so that the resin is evenly distributed on the surface of the steel mesh under the action of centrifugal force and is not affected by gravity and is concentrated at the bottom until the resin is completely solidified.

[0068] In step S5, after the resin is solidified, the end positioning plates 3 and the frame strips 1 are removed in sequence. The steel mesh 2 is tightly combined with the fibers under the action of the resin and becomes part of the steel wire-FRP composite pipe and remains therein.

[0069] The present invention's production method utilizes the end positioning plates and the frame slats to construct frames of varying shapes and sizes. Elastic steel wire is wrapped around the frame to create a relatively smooth mesh profile, replacing the continuous surface profile of conventional molds. Resin-impregnated fibers are then wrapped or wet-laid onto the wire mesh, enabling the production of steel-FRP composite tubes of varying shapes and sizes using a single mold. The wire mesh remains within the steel-FRP composite tube, while the frame slats and end positioning plates are easily removable. This production method directly avoids the challenges of machining, installation, disassembly, and reuse of complex molds. Its flexibility and simplicity make it suitable for large-scale industrial production and application.

[0070] In order to make the above implementation details and operations of the present application clearly understood by those skilled in the art, and to demonstrate the significant improvement in the performance of the mold for preparing the steel wire-FRP composite pipe and the preparation method thereof in the embodiment of the present application, the above technical solution is illustrated by multiple embodiments below.

[0071] Example 1

[0072] like Figure 1As shown, the skeleton strips 1 of the mold for preparing steel wire-FRP composite pipes in this embodiment are straight strips and there are 10 of them. The number of slots 3-2 is 90, wherein the skeleton strips 1 are inserted on the end positioning plate 3 at equal intervals, and the position of each skeleton strip 1 in the slot 3-2 is consistent. Finally, this embodiment can be used to prepare the following Figure 1 The cross section shown is a steel wire-FRP composite tube with a circular shape.

[0073] Example 2

[0074] like Figure 5 As shown, the mold of this embodiment is different from that of embodiment 1 in that the number of skeleton slats 1 in this embodiment is 12, and the positions of the skeleton slats on the end positioning plate are different from those in embodiment 1. Specifically, the 12 skeleton slats 1 of this embodiment are divided into 4 groups, each group has 3 skeleton slats 1, which are inserted into the slots 3-2 of the end positioning plate 3 at equal intervals. The skeleton slats 1 between each group are arranged at intervals of one slot 3-2, and the position of each skeleton slat 1 in the slot 3-2 is consistent. Finally, this embodiment can be used to prepare the following Figure 5 The cross section shown is a steel wire-FRP composite tube with a square shape.

[0075] Example 3

[0076] like Figure 6 As shown, the mold of this embodiment differs from that of Example 1 in that the number of skeleton slats 1 in this embodiment is 24, and the positions of the skeleton slats on the end positioning plate are different from those in Example 1. Specifically, the 24 skeleton slats 1 of this embodiment are inserted into the slots 3-2 of the end positioning plate 3 at equal intervals, but the positions of the skeleton slats 1 within the slots 3-2 are inconsistent, and the cross-section of the outer peripheral wall of the skeleton formed by the skeleton slats 1 is an elliptical steel wire-FRP composite tube.

[0077] Example 4

[0078] like Figure 7 As shown, the mold of this embodiment is the same as the mold of embodiment 1, except that the mounting position of the skeleton strip 1 on the slot 3-2 of the end positioning plate 3 is different. The fixed position of the skeleton strip 1 on the slot 3-2 of the end positioning plate 3 on one side is close to the center of the end positioning plate 3, and the fixed position on the slot 3-2 of the end positioning plate 3 on the other side is close to the outer peripheral wall of the end positioning plate 3, finally forming a mold that can be prepared as shown in FIG. Figure 7 The cross section shown is a truncated cone-shaped steel wire-FRP composite pipe whose cross section gradually increases from one side to the other side in the axial direction.

[0079] Example 5

[0080] like Figure 8As shown, the mold of this embodiment is different from the mold of Example 1 in that the skeleton strip 1 of the mold for preparing the steel wire-FRP composite pipe of this embodiment is curved, as shown in FIG. Figure 9 As shown, it includes a connecting section and an upper convex section and a lower concave section integrally provided between the connecting sections on both sides. The frame slats 1 of this embodiment include end positioning plates 3 provided on both sides in different fixed positions. Figure 8 The steel wire-FRP composite pipe is hourglass-shaped with a cross section that continuously changes along the axial direction.

[0081] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing a steel wire-FRP composite pipe, characterized in that: The steel wire-FRP composite pipe is prepared using a mold for preparing the steel wire-FRP composite pipe, wherein the mold for preparing the steel wire-FRP composite pipe comprises two coaxial end positioning plates (3) spaced apart in the axial direction, a skeleton composed of three or more skeleton strips (1) extending in the transverse direction, and a steel wire mesh (2) formed by spirally winding steel wire around the skeleton; The end positioning plate (3) comprises a plate body (3-1) and a plurality of slots (3-2) arranged at intervals on the outer peripheral wall of the plate body (3-1) and extending in the radial direction of the plate body (3-1); The transverse ends of each frame strip (1) are inserted into corresponding slots (3-2) of the two end positioning plates (3); A plurality of V-shaped teeth (1-1) are provided at intervals along the transverse direction on one side of the width direction of the skeleton strip (1); the included angle of each V-shaped tooth (1-1) is greater than or equal to 60° and not greater than 120°; The skeleton slats (1) are straight or curved slats; The preparation method comprises the following steps: S1: Install the two end positioning plates (3) coaxially and spaced correspondingly; S2: applying a release agent to the skeleton strips (1), and then respectively installing the skeleton strips (1) coated with the release agent on the slots (3-2) of the end positioning plates (3), and adjusting and fixing the positions of the skeleton strips (1) to form the desired skeleton shape according to the shape requirements of the composite pipe to be prepared; S3: rotating the frame composed of the frame slats (1) and spirally winding the steel wire on the frame to form a steel wire mesh (2); S4: Wet-laying or winding the fibers impregnated with resin on the steel wire mesh (2); the steel wire direction and the fiber direction of the steel wire mesh (2) are not parallel; S5: After the fibers soaked in resin are solidified, the end positioning plates (3) and the skeleton strips (1) are removed in sequence. The steel mesh (2) is tightly combined with the fibers under the action of the resin and becomes a part of the steel wire-FRP composite pipe and remains therein.

2. The preparation method according to claim 1, characterized in that The diameter of the steel wire is not less than 0.8 times the opening width of the V-shaped teeth (1-1) of the skeleton slats and is not greater than the opening width of the V-shaped teeth (1-1) of the skeleton slats.

3. The preparation method according to claim 1, characterized in that The breaking strain of the steel wire is not less than 0.

1.

4. The preparation method according to claim 1, characterized in that The mold for preparing the steel wire-FRP composite pipe further comprises a rotating shaft (5); a through hole (3-3) for passing the rotating shaft (5) is provided at the center of the end positioning plate (3); and a limiting groove (3-4) communicating with the through hole (3-3) is provided beside the through hole (3-3).

5. The preparation method according to claim 1, characterized in that In step S2, when the skeleton strip (1) coated with a release agent is installed on the slot (3-2) of the end positioning plate (3), the side with the V-shaped teeth (1-1) is arranged outward.

6. The preparation method according to claim 1, characterized in that In step S4, the angle between the steel wire direction and the fiber direction of the steel wire mesh (2) is not less than 10°.

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