Composite core and cable with integral structural fiber reinforcement

Abstract

The present application relates to the technical field of composite core, and particularly relates to a composite core with integral structure fiber reinforcement and a cable comprising the same. The composite core with integral structure fiber reinforcement is obtained by impregnating a three-dimensional preform with resin and then performing pultrusion molding. The three-dimensional preform is a three-dimensional fabric formed by regularly and alternately interlocking a plurality of fiber bundles. The three-dimensional preform has an internal structure and an external contour which are interwoven into one body. The three-dimensional preform has an integral structure without delamination. The three-dimensional preform has an integral structure formed by fiber bundles without delamination and without a skin-core structure. The three-dimensional preform can be integrally formed in a net size. The three-dimensional preform has a multi-axial fiber reinforcement distribution feature. The composite core with integral structure fiber reinforcement has more prominent comprehensive performance such as tensile resistance, compression resistance, bending resistance and torsion resistance. The composite core with integral structure fiber reinforcement also has dynamic fatigue resistance and impact resistance. The composite core with integral structure fiber reinforcement has excellent comprehensive mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of composite core technology, and more particularly to a composite core with an integral fiber-reinforced structure and a cable including the composite core with the integral fiber-reinforced structure. Background Technology

[0002] High-performance fibers, due to their excellent mechanical properties, are combined with resin to prepare composite cores that replace steel strands as load-bearing structures and are widely used in power transmission cables. Among them, carbon fiber, with its characteristics of light weight, high corrosion resistance, non-magnetic properties, high thermal conductivity, extremely low coefficient of thermal expansion, high tensile strength, and high tensile elasticity, is the main application.

[0003] Conventional composite cores are obtained by pultruding high-performance fibers bundled along the axial direction (or by adding winding and tube weaving processes) after impregnation with resin to obtain a composite core with a certain cross-sectional shape.

[0004] Among them, the fiber-reinforced composite core prepared by unidirectional fiber pultrusion process has excellent axial tensile strength because the fiber filaments are only arranged parallel to each other along the axial direction. However, it lacks circumferential fiber reinforcement, and the parallel fiber filaments are only bonded by resin. Therefore, the resulting composite core has insufficient radial compression resistance and axial bending resistance. In particular, when the composite core is subjected to radial pressure, it is prone to splitting along the diameter direction. Under frequent external forces, the cracks will rapidly propagate along the interface where the fiber filaments and resin adhesive are poor, leading to the failure of the composite core.

[0005] Using a portion prepared by unidirectional fiber pultrusion as the core, a fiber winding process is added along the circumferential direction on the outside of the core to prepare a fiber-reinforced composite core with a surface helical structure. The wound fibers bind and tighten the core fibers, restricting their movement and improving radial compression resistance and axial bending resistance. However, the wound fibers are only helically stacked along a certain circumferential direction, and the contact surface between the fiber helical rings is small. They are only fixed by resin bonding, so the resulting composite core still exhibits poor torsional resistance and fatigue resistance.

[0006] Using a portion prepared by unidirectional fiber pultrusion process as the core, a fiber tubular braiding process is added along the circumferential direction on the outside of the core to prepare a fiber-reinforced composite core with a braided tube sleeve surface. The braided fibers form a tube sleeve outside the core fibers, and each fiber bundle braided into a tube is regularly cross-interlocked with the axis at a certain angle. This structure enhances the radial compressive strength and circumferential stiffness of the composite core, while also improving its torsional resistance and some axial tensile properties, which is an upgrade of the winding process.

[0007] While winding and braiding processes improve some circumferential properties of unidirectional fiber pultruded composite cores to varying degrees, their combination with unidirectional fiber pultrusion results in a "skin-core structure," where the winding and braiding layers act as the skin, and the unidirectional fiber pultruded portion forms the core. In the production of such components, delamination easily occurs when the winding or braiding rate is abnormally matched with the pultrusion rate, severely impacting product performance. Furthermore, the skin layer cannot effectively control the propagation of cracks within the core; once the core is damaged, the composite core still tends to fail rapidly. Therefore, composite cores with a "skin-core structure" exhibit poor fatigue resistance and impact resistance. This poor overall mechanical performance limits the application of composite cores, making it difficult to meet more demanding usage requirements. Summary of the Invention

[0008] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a composite core with an integral structure and fiber reinforcement, which has excellent comprehensive mechanical properties.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] This invention provides a composite core with an integral fiber reinforcement structure. The composite core is obtained by impregnating a three-dimensional preform with resin and pultruding it. The three-dimensional preform is a three-dimensional fabric composed of several fiber bundles interlocked in a regular manner. The three-dimensional preform has an internal structure and an outer contour that are interwoven with each other. The three-dimensional preform is an integral structure without layers.

[0011] Preferably, continuous fiber bundles distributed circumferentially are arranged on the outer contour of the three-dimensional preform.

[0012] Preferably, the three-dimensional preform is prepared by a three-dimensional weaving process from fiber bundles.

[0013] Preferably, the resin impregnation of the three-dimensional preform is carried out by resin pressure injection impregnation.

[0014] Preferably, the fiber bundle is any one or a combination of carbon fiber, glass fiber, ultra-high molecular weight polyethylene fiber, aramid fiber, polyimide fiber, PBO fiber, hybrid fiber, modified fiber, and plant fiber.

[0015] Preferably, the resin is any one or a combination of two of thermoplastic resins and thermosetting resins.

[0016] The present invention also provides a cable comprising a composite core having an integral structure and fiber reinforcement as described above.

[0017] Compared with the prior art, the present invention has significant progress:

[0018] This invention utilizes a three-dimensional preform impregnated with resin and pultruded to obtain a composite core with an integral fiber-reinforced structure. The three-dimensional preform is a complete, non-layered, core-skin-free integral structure composed of fiber bundles, which can be integrally molded to net dimensions. It features multi-axial fiber reinforcement, resulting in a composite core with superior comprehensive properties such as tensile, compressive, flexural, and torsional strength. It also exhibits excellent dynamic fatigue and impact resistance, demonstrating excellent overall mechanical properties. Furthermore, it boasts advantages such as high integral structural formability, outstanding conformal design capability, strong designability of multi-axial properties, robustness, toughness, and lightweight. This invention combines three-dimensional preform molding with composite core pultrusion, fully leveraging the continuous, low-cost, high-efficiency, and high-quality control characteristics of composite core pultrusion, as well as the ability of three-dimensional preforms to effectively improve interlayer shear resistance, impact resistance, fatigue resistance, and integral net-dimensional molding. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the composite core with integral fiber reinforcement according to an embodiment of the present invention.

[0020] Figure 2 This is a partial structural schematic diagram of a three-dimensional preform in a composite core with an integral fiber-reinforced structure according to an embodiment of the present invention.

[0021] Figure 3 This is a side view of the three-dimensional preform in the composite core with integral fiber reinforcement according to an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of the three-dimensional textile machine used in this embodiment of the invention.

[0023] Figure 5 This is a schematic diagram of the fiber bundle preforming and bundling device used in an embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram of the cross-sectional structure of a three-dimensional preform in a composite core with an integral fiber-reinforced structure according to an embodiment of the present invention.

[0025] Figure 7 This is a schematic cross-sectional view of a composite core with an integral fiber reinforcement structure according to an embodiment of the present invention.

[0026] Figure 8 This is a schematic diagram of the manufacturing process route for a composite core with an integral fiber-reinforced structure, according to an embodiment of the present invention.

[0027] Figure 9 This is a schematic diagram of the preforming device used in the embodiments of the present invention.

[0028] Figure 10This is a schematic diagram of the compression device used in an embodiment of the present invention.

[0029] Figure 11 This is a schematic diagram of the structure of the shaping mold used in the embodiments of the present invention.

[0030] The reference numerals in the attached figures are explained as follows:

[0031] 100 Three-dimensional prefabricated bodies

[0032] 101 warp yarns

[0033] 102, 102a weft yarn

[0034] 200 resin

[0035] 201 Resin Surface Layer

[0036] 202 Resin Filler Layer

[0037] 300 Three-Dimensional Textile Machine

[0038] 301 steel reed

[0039] 302 Fabric Area

[0040] 400 Fiber Bundle Preforming and Bundling Device

[0041] 1. Yarn frame

[0042] 2. Three-dimensional preform forming device

[0043] 3 Preforming device

[0044] 31 Pre-formed opening and closing part

[0045] 32 Preforming cavity

[0046] 32a Preformed straight section

[0047] 32b Preformed flared section

[0048] 4. Preheating device

[0049] 5. Compression device

[0050] 51 Compression opening and closing part

[0051] 52 Compression Chamber

[0052] 52a Compression Straight Section

[0053] 52b Compression flared section

[0054] 53 First resin injection port

[0055] 6. Shaping device

[0056] 61. Molding mold

[0057] 62 Shaping cavity

[0058] 63 Second resin injection port

[0059] 64 Mixed Head

[0060] 7 Traction Machine Detailed Implementation

[0061] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0062] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0063] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0064] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0065] In existing technologies, to compensate for the insufficient circumferential properties of unidirectional fiber pultruded composite cores, processes such as winding and braiding are used to add winding / braiding layers to the outer periphery of the core prepared by unidirectional fiber pultrusion through layer-by-layer stacking. If adding one layer still does not meet the requirements, multiple layers are considered. However, regardless of the number of layers added, the final result is a core-skin structure, which cannot prevent the separation of the skin and core interface when the composite core fails. Furthermore, the skin layer is unable to effectively inhibit the propagation of crack damage within the core layer, leading to rapid failure of the composite core and poor overall mechanical properties.

[0066] To overcome the defects of the core-sheath structure, this invention proposes a composite core with an integral fiber reinforcement structure. The fibers in this composite core form a complete, non-layered, core-sheath structure. The composite core with this integral fiber reinforcement structure has more outstanding comprehensive performance in terms of tensile, compressive, bending, and torsional strength, and can also have dynamic fatigue and impact resistance, thus exhibiting superior comprehensive mechanical properties.

[0067] In composite materials other than composite cores, existing research has used three-dimensional preforms with integral structures as reinforcements. However, these composite materials are all manufactured in a segmented manner, meaning a certain number of products are produced at a time using a single mold, and then repeated in multiple batches, resulting in high manufacturing costs and low production efficiency. Pultrusion molding of composite cores, on the other hand, is one of the few processes in the field of composite materials that allows for continuous production, produces products with outstanding mechanical properties in the pultrusion direction, and maintains extremely high quality consistency, perfectly meeting the low-cost, high-quality requirements of industrialization. However, in existing research, researchers in composite core pultrusion processes focus too much on improving the performance of composite cores in a single direction, while researchers in other composite material processing directions focus too much on optimizing the manufacturing cost and production efficiency of segmented batch production of three-dimensional preforms. Furthermore, because existing composite cores use winding and braiding processes to form winding and braiding layers as reinforcements, their molding mechanism is relatively simple, and their structure is not complex. Equipment control, manufacturing quality control, and especially the control of resin impregnation are easier compared to three-dimensional preforms. Therefore, current research on composite cores still focuses on improving the performance of the core-skin structure, without considering the use of three-dimensional preforms in composite core preparation. This reflects a technological bias within the field of composite core preparation.

[0068] This invention overcomes the aforementioned technical biases by combining three-dimensional preform molding with composite core pultrusion molding to obtain a composite core with an integral fiber-reinforced structure. Three-dimensional preforms possess advantages such as strong designability, outstanding comprehensive performance (especially in terms of delamination resistance, impact resistance, and fatigue resistance), high added value, and relatively high manufacturing costs (mainly due to significant waste during segmented manufacturing). The continuous fabrication process of composite core pultrusion precisely offsets the high manufacturing cost of three-dimensional preforms. This results in a composite core with superior comprehensive mechanical properties. Furthermore, by integrating three-dimensional preform molding into the continuous fabrication process of composite core pultrusion, manufacturing costs and production efficiency can be effectively and rationally controlled. This fully leverages the continuous, low-cost, high-efficiency, and high-quality control characteristics of composite core pultrusion molding, as well as the ability of three-dimensional preforms to effectively improve interlayer shear resistance, impact resistance, fatigue resistance, and the ability to be integrally molded to net dimensions.

[0069] Furthermore, existing composite core resin impregnation methods mostly employ grooved resin baths. The degree of resin impregnation is significantly affected by resin flowability and impregnation time. When combining three-dimensional preform molding with composite core pultrusion, if a grooved resin bath is used, the complex internal structure of the three-dimensional preform makes it difficult for the resin to impregnate the interior through its own flow. Incomplete impregnation results in numerous pores within the three-dimensional preform, severely impacting the composite core's performance. To address the issue of resin impregnation within the three-dimensional preform, this invention proposes applying resin injection impregnation to the three-dimensional preform in the composite core pultrusion process. Resin injection impregnation technology originated in the field of plastic extrusion technology. It involves injecting liquid resin under pressure into a target-sized mold cavity containing fibers using a separate machine. High-quality resin impregnation is achieved by utilizing high pressure, a specific cavity structure, injection port location, and good sealing. This technology has been widely applied in the field of segmented batch preparation of composite materials. However, due to the high requirements for sealing, pressure, and injection volume in the injection system, it has not been applied in the field of continuous composite core pultrusion. To address the problem that conventional grooved resin baths are insufficient for thoroughly impregnating three-dimensional preforms, this invention combines resin injection impregnation with composite core pultrusion molding, thereby forming a continuous process system for preparing composite cores with integral structural fiber reinforcement through three-dimensional preform molding, resin injection impregnation, and pultrusion molding.

[0070] Based on this, the present invention provides a composite core with an integral fiber-reinforced structure and a cable including the composite core with the integral fiber-reinforced structure.

[0071] like Figures 1 to 11 The image shows an embodiment of a composite core with an integral fiber reinforcement structure provided by the present invention.

[0072] See Figure 1 In this embodiment, the composite core with integral fiber reinforcement is obtained by impregnating a three-dimensional preform 100 with resin 200 and pultruding it. The three-dimensional preform 100 is a three-dimensional fabric composed of several fiber bundles interlocked in a regular manner. The three-dimensional preform 100 has an internal structure and an outer contour that are interwoven with each other. The three-dimensional preform 100 is an integral structure without layers.

[0073] In this embodiment, the three-dimensional preform 100 is a complete, non-layered, core-skin structure composed of fiber bundles, which can be integrally molded to net dimensions. It has the characteristics of multi-axial fiber reinforcement distribution, which makes the composite core with integral structure fiber reinforcement in this embodiment have more outstanding comprehensive performance in terms of tensile, compressive, bending and torsional strength. At the same time, it also has dynamic fatigue and impact resistance, excellent comprehensive mechanical properties, and has the advantages of high integral structure formability, outstanding conformal design capability, strong designability of multi-axial performance, strong and toughness and light weight.

[0074] In this embodiment, preferably, continuous fiber bundles distributed circumferentially are arranged on the outer contour of the three-dimensional preform 100. These continuous fiber bundles form part of the outer contour of the three-dimensional preform 100, constrain the internal structure of the three-dimensional preform 100, and are intertwined with the internal structure of the three-dimensional preform 100, without forming a core-skin structure.

[0075] In this embodiment, preferably, the three-dimensional preform 100 is prepared from fiber bundles using a three-dimensional weaving process. During preparation, the fiber bundles are used as yarns. By combining techniques such as yarn opening configuration, yarn specification configuration, and continuous weft weaving, the integrated net-size molding of the three-dimensional preform 100 can be achieved, giving the obtained three-dimensional preform 100 the basic net-size outline of the target composite core. Then, the three-dimensional preform 100 is impregnated with resin and further pultruded to obtain the target composite core with the target cross-sectional shape, i.e., the composite core with integral fiber reinforcement in this embodiment. It should be noted that the three-dimensional weaving process is a mature existing technology. However, when used to prepare the three-dimensional preform 100 in this embodiment, to facilitate resin impregnation and pultrusion molding of the three-dimensional preform 100, the adopted three-dimensional weaving process can be optimized and adjusted to obtain a three-dimensional preform 100 that is infinitely close to a cylindrical shape and has a relatively uniform internal structure.

[0076] Specifically, the three-dimensional preform 100 obtained by forming fiber bundles through a three-dimensional weaving process is as follows: Figure 2 and Figure 3 As shown, the fiber bundle, acting as yarn, is divided into warp yarn 101 and weft yarn 102. Warp yarn 101 extends along the pultrusion direction of the composite core (warp direction), while weft yarn 102 extends along a direction perpendicular to the warp direction in the horizontal plane (weft direction). In the three-dimensional weaving process, warp yarn 101 overlaps different layers of weft yarn 102 through bending. After a regular cycle, the stacking of the cross-sections of weft yarn 102 achieves an interlocking overall structure, thus obtaining the three-dimensional preform 100. In practice, warp yarn 101 and weft yarn 102 are mutually bent, but the degree of bending of warp yarn 101 is less than that of weft yarn 102 because warp yarn 101 experiences greater traction. The overall structure of the three-dimensional preform 100 can be freely designed by changing the number and span of the yarn bending points. The fewer the yarn bending points and the larger the span of the yarn bending points, the stronger the deformation capacity of the three-dimensional preform 100, and the better the mechanical properties along the yarn extension direction. The three-dimensional textile machine 300 is a device that enables the warp yarns 101 and weft yarns 102 to alternate and interlock in a regular three-dimensional weaving process. It is an existing device, and its structural diagram is shown below. Figure 4As shown, during operation, the yarn (fiber bundle) is formed after passing through the heddle holes and reed 301 of the three-dimensional textile machine 300. The heddle holes of the existing three-dimensional textile machine 300 are arranged in a spatial rectangular pattern. The heddle holes of the three-dimensional textile machine 300 move up and down. The upward movement can lift the fiber bundle, and the lifted fiber bundle forms a triangular opening with the unlifted fiber bundle. After the weft yarn 102 is introduced into the opening, the reed 301 pushes the weft yarn 102 into the triangular opening and tightens it. Subsequently, the lifted fiber bundle descends, and the previously unlifted fiber bundle is lifted, repeating this cycle to form a cross-interlocking structure between the fiber bundles. In this embodiment, the heddle holes of the three-dimensional textile machine 300 are preferably designed to be inclined forward and backward and left and right to reduce friction between the yarns. In this embodiment, a fiber bundle pre-forming and bundling device 400 is provided on the rear side of the yarn area 302 at the rear end of the three-dimensional textile machine 300, such as... Figure 5As shown, the fiber bundle preforming and bundling device 400 has several grids, each grid constraining one fiber bundle. Each grid corresponds one-to-one with the heddle holes of the three-dimensional textile machine 300. Based on the target composite core diameter, fiber volume content, linear density and bulk density of the fiber raw material, the required number of fiber bundles can be calculated. After comprehensively considering the target composite core diameter and the warp distribution points of the three-dimensional textile machine, a square grid is formed on the fiber bundle preforming and bundling device 400. Combined with the amount of fiber bundles used, a circle is drawn within the square grid. The area inside this circle is the yarn distribution area. The required number of fiber bundles are evenly arranged inside the circle. First, fiber bundles are arranged in complete single cells within the circle. At the edge of the circle, fiber bundles are arranged in cells whose area inside the circle exceeds two-thirds of the area of ​​a single cell. Fiber bundles are not arranged in cells whose area inside the circle is less than one-third of the area of ​​a single cell. In the initial stage of fiber bundle formation into a three-dimensional preform, the fiber bundle preforming and bundling device 400 is placed behind the yarn area 302 of the three-dimensional textile machine 300. After the fiber bundle passes through the heddle holes and reed 301 of the three-dimensional textile machine 300, it passes through the fiber bundle preforming and bundling device 400 and is constrained within the yarn area on the square grid of the fiber bundle preforming and bundling device 400. When the fiber bundle is formed into a three-dimensional preform 100 by the three-dimensional textile machine 300, the fiber bundle preforming and bundling device 400 is pulled along behind the three-dimensional preform 100. The fiber bundles advance synchronously. As the forming length of the three-dimensional preform 100 in front of the fiber bundle preforming and gathering device 400 continuously increases, when the fiber bundles not involved in forming and the formed three-dimensional preform portion can pass through the subsequent path and be held by the traction force, the fiber bundle preforming and gathering device 400 is disassembled, allowing it to exit the fiber bundle advancing path. This enables the formed three-dimensional preform 100 to smoothly enter the next process, while the three-dimensional textile machine 300 continuously forms the three-dimensional preform 100 under the traction force. Thus, the fiber bundle preforming and gathering device 400 performs a preforming and gathering function for the initial forming of the fiber bundles, ensuring the straightness and contour forming quality of the three-dimensional preform 100, improving the circularity of the outer contour of the three-dimensional preform 100 with the target composite core, and obtaining a three-dimensional preform 100 with a shape close to that of the target composite core.

[0077] Figure 6This paper illustrates the yarn threading pattern on the cross-sectional structure of a three-dimensional prefabricated body 100 formed using a three-dimensional weaving process. Weft yarns 102a are arranged circumferentially on the outer contour of the three-dimensional prefabricated body 100. These weft yarns 102a are continuous fiber bundles distributed circumferentially on the outer contour of the three-dimensional prefabricated body 100. The continuous weft yarns 102a interlock different warp yarn layers and form a circumferential fiber binding process on the surface. The weft yarns 102a extend in different directions, and their paths bypass the warp yarns 101 arranged at the circular edge without interruption. The continuous weft yarn structure 102a constrains the warp yarns 101 in a quasi-wrap manner along the circumference of the three-dimensional prefabricated body 100, further realizing the integration of the internal structure and outer contour of the three-dimensional prefabricated body 100 without layering. The closed-loop weft yarn structure formed at the edges of different warp yarn layers is one of the foundations for the integral molding of the three-dimensional prefabricated body 100. In particular, in actual operation, at the warp yarn arrangement points on the circular edge, additional fine tension yarns or increased tension of the warp yarns at the circular edge points can be added to improve the molding quality of the three-dimensional preform 100.

[0078] Figure 7 The diagram shows the cross-sectional structure of a composite core with an integral fiber reinforcement, prepared from a three-dimensional preform 100 formed using a three-dimensional weaving process. When the preform 100 is impregnated with resin 200, the fiber bundles on the outer contour surface of the preform 100 are covered by the resin 200, forming a resin surface layer 201. Furthermore, the resin 200 penetrates the internal space of the preform 100, filling the gaps between the fiber bundles, forming a resin filling layer 202. The resin-impregnated preform 100 is then pultruded and cured to obtain the composite core with an integral fiber reinforcement.

[0079] It should be noted that, Figure 6 and Figure 7 To illustrate the layers of warp yarn 101, weft yarn 102, and resin 200, they are shown using elliptical cross-sections, solid lines, and dashed lines, respectively. In practical applications, warp yarn 101 and weft yarn 102 are irregular strip-shaped fiber bundles that, after regular alternation and interlocking, roughly form a flattened oval shape. During pultrusion molding of the three-dimensional preform 100, the fiber bundles move relative to each other to fill the larger gaps in the internal structure of the three-dimensional preform 100, and the resin 200 further fills all the gaps. In the figure, to distinguish the layers of warp yarn 101, weft yarn 102, and resin 200, the boundaries and positions of the circumferentially distributed fiber bundles and resin 200 on the outer contour of warp yarn 101, weft yarn 102, and resin 200 have been enlarged for clearer display.

[0080] In this embodiment, to ensure the degree of resin impregnation within the three-dimensional preform 100, preferably, the resin 200 is impregnated by resin pressure injection.

[0081] In this embodiment, the fiber bundle can be any one or a combination of carbon fiber, glass fiber, ultra-high molecular weight polyethylene fiber, aramid fiber, polyimide fiber, PBO fiber (short for poly(p-phenylenebenzodioxazole) fiber), hybrid fiber (a mixture of various different fibers), modified fiber (such as fibers with carbon nanotubes, toughening particles, etc. introduced into the surface of an existing fiber to improve certain properties), and plant fiber (such as lignin fiber). The composite core with integral fiber reinforcement in this embodiment is mainly used in cables; therefore, the fiber bundles used are primarily carbon fiber.

[0082] In this embodiment, resin 200 can be any one or a combination of thermoplastic resin and thermosetting resin (such as adding toughening particles of thermoplastic resin to thermosetting resin).

[0083] Figure 8 The manufacturing process route of the composite core with integral fiber reinforcement of this embodiment is shown. The composite core with integral fiber reinforcement of this embodiment can be prepared by sequentially performing the following steps.

[0084] Step 1: Regularly interlock several fiber bundles to form a three-dimensional preform 100. A three-dimensional weaving process is preferred, with fiber bundles as yarns (warp yarns 101 and weft yarns 102). The fiber bundles are placed on the yarn frame 1 in a wound state on a spool. The fiber bundles are unwound from the spool into a single bundle and introduced into the three-dimensional preform forming device 2 (three-dimensional textile machine 300 and fiber bundle preforming and bundling device 400) through ceramic eyes. After passing through the heddle holes and reed 301 of the three-dimensional textile machine 300, they are formed into a three-dimensional preform 100 with a shape close to that of the target composite core. In the initial stage of forming, the fiber bundle preforming and bundling device 400 is placed behind the yarn area 302 of the three-dimensional textile machine 300 to preform and bundle the fiber bundles. After a certain length of three-dimensional preform has been formed, when the fiber bundles that have not participated in the forming and the formed three-dimensional preform can pass through the subsequent path and be pulled and held by the traction force, the fiber bundle preforming and bundling device 400 is disassembled and removed from the fiber bundle forward path. This achieves integrated net-size molding of the three-dimensional preform 100, and gives the resulting three-dimensional preform 100 the basic net-size outline of the target composite core.

[0085] Step 2: Pre-process the three-dimensional preform 100. Preferably, the pre-processing includes primary molding, preheating, and secondary molding. Primary molding compresses the three-dimensional preform 100 obtained in Step 1, preheating preheats the three-dimensional preform 100 after primary molding, and secondary molding compresses the three-dimensional preform 100 after preheating.

[0086] The primary molding process is completed using preforming device 3. (See also...) Figure 9In this embodiment, preferably, the preforming device 3 includes two preforming opening and closing portions 31 that are separated or joined opposite each other along the compression direction A of a single compression. A through preforming cavity 32 is formed between the two joined preforming opening and closing portions 31. The preforming cavity 32 includes a preforming straight section 32a with a diameter smaller than the outer contour diameter of the three-dimensional preform 100, and a preforming flared section 32b with a gradually increasing diameter extending from both ends of the preforming straight section 32a. When the three-dimensional preform 100 passes through the preforming cavity 32 of the preforming device 3, the two preforming opening and closing portions 31 regularly separate and join, and the three-dimensional preform 100 is shaped into a relatively uniform target diameter through the preforming straight section 32a of the preforming cavity 32. The opening and closing speed of the preforming device 3 is matched with the forward speed of the three-dimensional preform 100, so that the length of each compression can overlap end-to-end, avoiding omissions. The length of the preforming cavity 32 in the preforming device 3 is related to the target diameter. The larger the target diameter, the longer the preforming cavity 32 should be, and the more opening and closing force points should be added to ensure uniform compression force. The preforming flared sections 32b at both ends of the preforming cavity 32 facilitate the introduction and export of the three-dimensional preform 100 into and out of the preforming cavity 32. Preferably, the two preforming flared sections 32b and the preforming straight section 32a are smoothly connected by chamfers to avoid sharp edges or corners that could damage the three-dimensional preform 100 and to prevent large indentations. Preferably, the cavity wall of the preforming cavity 32 is coated to improve the wear resistance of the preforming cavity 32 and reduce the coefficient of friction.

[0087] Preheating is accomplished by preheating device 4. Preheating device 4 can be a conventional heating device.

[0088] Secondary molding is completed by compression device 5. See also Figure 10In this embodiment, preferably, the compression device 5 includes two compression opening and closing parts 51 that are separated or joined opposite each other along the compression direction B of the secondary compression. A through compression cavity 52 is formed between the two joined compression opening and closing parts 51. The compression cavity 52 includes a compression straight section 52a with a diameter not greater than the outer contour diameter of the three-dimensional preform 100 after the first compression and a compression flared section 52b with a gradually increasing diameter extending from both ends of the compression straight section 52a. When the preheated three-dimensional preform 100 passes through the compression cavity 52 of the compression device 5, the two compression opening and closing parts 51 are regularly separated and joined. The compression straight section 52a of the compression cavity 52 performs a second-order shaping of the three-dimensional preform 100 to the target diameter, further compressing the excess elastic relaxation space within the three-dimensional preform 100 to ensure the fiber volume content and molding quality of the final composite core, and to make the shape of the three-dimensional preform 100 close to the shape of the target composite core. The opening and closing speed of the compression device 5 is coordinated with the forward speed of the three-dimensional preform 100, ensuring that the length of each compression overlaps end-to-end to avoid omissions. The length of the compression chamber 52 of the compression device 5 is related to the target diameter; the larger the target diameter, the longer the compression chamber 52 should be, and the more opening and closing points should be added to ensure uniform compression force. The compression flared sections 52b at both ends of the compression chamber 52 facilitate the introduction and removal of the three-dimensional preform 100 into and out of the compression chamber 52. Preferably, the two compression flared sections 52b and the compression straight section 52a are smoothly connected by chamfers to avoid sharp edges or corners that could damage the three-dimensional preform 100 and to prevent large indentations. Preferably, the cavity wall of the compression chamber 52 is provided with a wear-resistant and non-stick coating to improve the wear resistance of the compression chamber 52 and reduce the coefficient of friction.

[0089] Furthermore, in step two, during the secondary molding, the preheated three-dimensional preform 100 can also be pre-impregnated with resin. Resin pre-impregnation is preferably performed by resin pressure injection. The secondary molding and resin pre-impregnation can be completed using the compression device 5. See also... Figure 10In a preferred embodiment, at least one compression opening / closing part 51 of the compression device 5 is provided with a first resin injection port 53 communicating with the compression chamber 52. The first resin injection port 53 is used to inject resin into the compression chamber 52 under pressure. The first resin injection port 53 is connected to a resin injection system, which is existing equipment. A resin recovery device can be provided below the compression device 5 to receive excess resin squeezed out from the compression device 5. During each opening and closing process of the compression device 5, a resin injection is completed into the compression chamber 52 through the first resin injection port 53. The resin impregnates into the three-dimensional preform 100 under injection pressure. Furthermore, relying on the closing compression force of the compression device 5 and capillary effect, the resin gradually diffuses within the three-dimensional preform 100, forming preliminary impregnation. Excess resin is squeezed out of the compression device 5, recovered and filtered by the recovery device below the compression device 5, and returned to the resin injection system. This achieves secondary molding and resin pre-impregnation of the three-dimensional preform 100. Preferably, each of the two compression opening and closing parts 51 is provided with a first resin injection port 53. The two first resin injection ports 53 are located at the two ends of the compression straight section 52a and are arranged in alignment along the compression direction B of the secondary compression. By counteracting the pressure of the two aligned first resin injection ports 53, the three-dimensional preform 100 can be thoroughly impregnated and the resin overflow from the break of the compression device 5 can be reduced.

[0090] Therefore, in step two, the shape of the three-dimensional preform 100 after secondary molding and resin pre-impregnation is approximately the target shape of the fiber-reinforced composite material, and resin 200 diffuses into the internal structure of the three-dimensional preform 100 after secondary molding and resin pre-impregnation to form preliminary resin impregnation.

[0091] Preferably, the compression direction A of the preforming device 3 performing a primary compression on the three-dimensional preform 100 is perpendicular to the compression direction B of the compression device 5 performing a secondary compression on the three-dimensional preform 100. More preferably, the compression direction A of the primary compression is horizontal, and the compression direction B of the secondary compression is vertical. The perpendicularity of the two compression directions can neutralize the indentation deformation, making the cross-section of the three-dimensional preform 100 after the two compressions more complete.

[0092] Step 3: The pretreated three-dimensional preform 100 is impregnated with resin and pultruded to form a composite core with an integral fiber-reinforced structure. This step 3 is completed by the shaping device 6. See also... Figure 8 and Figure 11The shaping device 6 includes a shaping mold 61, with a shaping cavity 62 extending through the direction of the traction force inside the shaping mold 61. The shaping mold 61 has a second resin injection port 63 connected to the shaping cavity 62 and a high-temperature curing zone for heating the interior of the shaping cavity 62. The second resin injection port 63 is used to inject resin into the shaping cavity 62 under pressure. The high-temperature curing zone is located on the side of the second resin injection port 63 away from the compression device 5. The shaping cavity 62 of the shaping mold 61 has a relatively long length, and the end of the shaping cavity 62 near the compression device 5 is designed as an outwardly expanding funnel shape to facilitate the entry of the pre-treated three-dimensional preform 100 into the shaping cavity 62 of the shaping mold 61. The three-dimensional preform 100, after secondary compression and shaping by the compression device 5 after pre-treatment, can more easily enter the shaping mold 61 of the shaping device 6. The second resin injection port 63 can be connected to a resin injection system via a mixing head 64; the resin injection system is existing equipment. When the pre-treated three-dimensional preform 100 passes through the shaping cavity 62 of the shaping mold 61, the resin in the resin injection system undergoes its first degassing under ultrasonic waves. It is then injected into the shaping cavity 62 under high pressure through the second resin injection port 63, completing the final injection impregnation of the three-dimensional preform 100. Preferably, an ultrasonic transmitter is arranged outside the resin impregnation area of ​​the shaping mold 61 at the second resin injection port 63. A certain frequency is set to allow the ultrasonic waves to penetrate the three-dimensional preform 100 and the impregnated resin, thereby further promoting the degassing of the resin injected into the three-dimensional preform 100 and reducing the porosity inside the composite core. After final impregnation, the three-dimensional preform 100 is heated in a high-temperature curing zone to solidify and shape the resin-impregnated three-dimensional preform 100. Finally, it is pulled out of the shaping mold 61 to obtain a composite core with an integral fiber-reinforced structure. Preferably, a collection system for collecting composite cores can be provided on the side of the shaping mold 61 away from the compression device 5. The composite cores pulled out from the shaping mold 61 are collected by the collection system after being cooled. The preferred collection method is coil collection.

[0093] In this embodiment, the fiber bundle, the three-dimensional preform 100, and the composite core are pulled forward by the same traction force, and steps one to three are performed continuously under this traction force. See also Figure 8 In this embodiment, the traction machine 7 provides the traction force to pull the fiber bundles on the yarn frame 1 to the collection system. The fiber bundles on the yarn frame 1 are sequentially pulled through the three-dimensional preform forming device 2 (three-dimensional textile machine 300 and fiber bundle preform bundling device 400) to form a three-dimensional preform 100. The three-dimensional preform 100 is then pulled through the preform device 3, preheating device 4, compression device 5 and shaping device 6 to form a composite core with an integral structure and fiber reinforcement. The composite core is then pulled out of the shaping device 6, cooled, and enters the collection system. This forms a continuous preparation process system of three-dimensional preform forming-resin injection impregnation-pultrusion molding, which can be used to prepare the composite core with an integral structure and fiber reinforcement in this example.

[0094] Based on the composite core with integral fiber reinforcement described in this embodiment, this embodiment also provides a cable, which includes the composite core with integral fiber reinforcement described in this embodiment.

[0095] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A composite core having a unitary structural fiber reinforcement, characterized by, The composite core is obtained by impregnating resin into a three-dimensional preform and performing pultrusion, the three-dimensional preform is a three-dimensional fabric formed by regularly and alternately interlocking a plurality of fiber bundles, the three-dimensional preform is formed with an internal structure and an outer contour interwoven into one body, and the three-dimensional preform is an integral structure without delamination; the three-dimensional preform is pretreated before impregnating resin and performing pultrusion, the pretreatment includes primary shaping, preheating and secondary shaping, the primary shaping is to compress the three-dimensional preform once, the preheating is to preheat the three-dimensional preform after the primary shaping, and the secondary shaping is to compress the three-dimensional preform after the preheating again; the primary shaping is completed by a preforming device, the secondary shaping is completed by a compression device, and the compression direction of the preforming device for compressing the three-dimensional preform once is perpendicular to the compression direction of the compression device for compressing the three-dimensional preform again.

2. The composite core with integral structural fiber reinforcement of claim 1, wherein, The three-dimensional preform is provided with continuous fiber bundles distributed in a circumferential direction on the outer contour.

3. The composite core with integral structural fiber reinforcement of claim 1, wherein, The three-dimensional preform is prepared from the fiber bundles by a three-dimensional weaving process.

4. The composite core having integral structural fiber reinforcement of claim 1, wherein, The three-dimensional preform is impregnated with resin by a resin pressure injection impregnation method.

5. The composite core having integral structural fiber reinforcement of claim 1, wherein, The fiber bundles are any one or a combination of carbon fibers, glass fibers, ultra-high molecular weight polyethylene fibers, aramid fibers, polyimide fibers, PBO fibers, hybrid fibers, modified fibers and plant fibers.

6. The composite core having integral structural fiber reinforcement of claim 1, wherein, The resin is any one or a combination of thermoplastic resin and thermosetting resin.

7. A cable, characterized by A composite core with an integral structure and fiber reinforcement as claimed in any one of claims 1 to 6. A composite core with an integral structure and fiber reinforcement as claimed in any one of claims 1 to 6.

Images