CN115570818A - Method for manufacturing fiber-reinforced composite core - Google Patents

Abstract

The invention relates to the technical field of composite cores, in particular to a manufacturing method of a fiber reinforced composite core, which sequentially comprises the following steps: the method comprises the following steps that firstly, a plurality of fiber bundles are regularly and alternately interlocked to form a three-dimensional prefabricated body, the three-dimensional prefabricated body is a three-dimensional fabric, the three-dimensional prefabricated body is formed into an internal structure and an external outline which are interwoven into a whole, and the three-dimensional prefabricated body is of a non-layered integral structure; step two, preprocessing the three-dimensional prefabricated body; step three, performing resin infiltration and pultrusion on the pretreated three-dimensional prefabricated body to form a fiber reinforced composite core; the fiber bundle, the three-dimensional prefabricated body and the fiber reinforced composite core are drawn and advanced by the same drawing force, and the step one to the step three are continuously carried out under the action of the drawing force. The three-dimensional prefabricated body is combined with the pultrusion process, so that the characteristics of continuity, low cost, high efficiency and high quality control of the pultrusion process and the characteristics of excellent comprehensive performance and capability of integrated net size molding of the three-dimensional prefabricated body are fully exerted.

Description

Method for manufacturing fiber-reinforced composite core

Technical Field

The invention relates to the technical field of composite cores, in particular to a manufacturing method of a fiber reinforced composite core.

Background

The high-performance fiber is combined with resin to prepare a composite core to replace a steel twisted core as a bearing structure by virtue of excellent mechanical properties, and is widely applied to power transmission cables. The carbon fiber is mainly applied to the carbon fiber with the characteristics of light weight, high corrosion resistance, non-magnetism, high thermal conductivity, extremely low thermal expansion coefficient, high tensile strength, high tensile elasticity and the like.

The conventional composite core is prepared by bundling and arranging high-performance fibers along the axial direction (or increasing winding and pipe sleeve weaving processes), soaking the high-performance fibers in resin, and then performing pultrusion to obtain the composite core with a certain cross-sectional shape.

The fiber reinforced composite core prepared by the unidirectional fiber pultrusion process has the advantages that all fiber monofilaments are arranged in parallel only along the axial direction, the axial tensile strength is excellent, but the fiber reinforcement is not arranged in the circumferential direction, and the parallel fiber monofilaments are bonded only by resin, so that the radial compression resistance and the axial bending resistance of the obtained composite core are insufficient. Particularly, when the composite core is radially pressed, the composite core is easy to split along the diameter direction, and under the action of frequent external force, cracks can quickly spread along the interface with poor adhesion between the fiber monofilaments and resin, so that the composite core fails.

The method comprises the steps of using a part prepared by a unidirectional fiber pultrusion process as a shaft core, adding a fiber winding process on the outer side of the shaft core along the circumferential direction, preparing the fiber reinforced composite core with a surface spiral structure, binding and tightening the fibers of the shaft core by the wound fibers, restricting the movement of the fibers of the shaft core, improving the radial compression resistance and the axial bending resistance, only spirally stacking the wound fibers along a certain circumferential direction, ensuring that the contact surface between spiral rings of the fibers is small, and only bonding and fixing the spiral rings of the fibers by resin, wherein the torsion resistance and the fatigue resistance of the obtained composite core still have poor performance.

The method is characterized in that a part prepared by a unidirectional fiber pultrusion process is used as a shaft core, a fiber tubular weaving process is added on the outer side of the shaft core along the circumferential direction, the prepared fiber reinforced composite core with a woven pipe sleeve surface layer is obtained, the woven fibers form a layer of pipe sleeve outside the fibers of the shaft core, and fiber bundles woven into pipes and the shaft line form a certain included angle for regular cross interlocking.

The winding and weaving process improves partial circumferential performance of the unidirectional fiber pultrusion composite core to different degrees, but the winding and weaving process and the unidirectional fiber pultrusion process are combined to form a skin-core structure, the winding layer and the weaving layer are both surface layers, and the unidirectional fiber pultrusion part is a shaft core. In the production of the components, when the winding or weaving rate is abnormally matched with the pultrusion rate, layering is easily formed, and the product performance is seriously influenced. In addition, the skin layer does not provide effective control over crack propagation within the core, and once the core is damaged, the composite core still has a tendency to fail rapidly. Therefore, the composite core with the skin-core structure has poor performances of fatigue resistance, impact resistance and the like. The poor performance of the comprehensive mechanical properties limits the application of the composite core and is difficult to meet the more severe use requirements.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a method for manufacturing a fiber-reinforced composite core, which can obtain a fiber-reinforced composite core having excellent overall mechanical properties.

In order to solve the technical problem, the invention adopts the following technical scheme:

the invention provides a manufacturing method of a fiber reinforced composite core, which sequentially comprises the following steps: the method comprises the following steps that firstly, a plurality of fiber bundles are regularly and alternately interlocked to form a three-dimensional prefabricated body, the three-dimensional prefabricated body is a three-dimensional fabric, the three-dimensional prefabricated body is formed into an internal structure and an external outline which are interwoven into a whole, and the three-dimensional prefabricated body is of a non-layered integral structure; step two, preprocessing the three-dimensional prefabricated body; step three, performing resin infiltration and pultrusion on the pretreated three-dimensional prefabricated body to form a fiber reinforced composite core; the fiber bundle, the three-dimensional prefabricated body and the fiber reinforced composite core are drawn and advanced by the same drawing force, and the step one to the step three are continuously carried out under the action of the drawing force.

Preferably, in step one, continuous fiber bundles distributed in the circumferential direction are arranged on the outer contour of the three-dimensional preform.

Preferably, in step one, a three-dimensional preform is prepared using a three-dimensional weaving process.

Preferably, in the second step, the pre-processing includes a primary molding, a preheating and a secondary molding, the primary molding performs a primary compression on the three-dimensional preform obtained in the first step, the preheating performs a preheating on the three-dimensional preform after the primary molding, and the secondary molding performs a secondary compression on the preheated three-dimensional preform.

Preferably, in the second step, a compression direction of the three-dimensional preform by the primary molding and a compression direction of the three-dimensional preform by the secondary molding are perpendicular to each other.

Preferably, in the second step, the shape of the three-dimensional preform after the secondary molding approximates the target shape of the fiber-reinforced composite core.

Preferably, in step three, the resin infiltration adopts a mode of infiltrating the three-dimensional preform by resin pressure injection.

Compared with the prior art, the invention has the remarkable progress that:

the manufacturing method of the fiber reinforced composite core combines the three-dimensional preform molding and the composite core pultrusion process, fully exerts the characteristics of continuity, low cost, high efficiency and high quality control of the composite core pultrusion process, effectively improves the comprehensive performances of interlayer shearing resistance, impact resistance, fatigue resistance and the like of the three-dimensional preform, and can realize integrated net size molding. The three-dimensional prefabricated body is an integral structure which is formed by fiber bundles completely, is not layered and has no skin-core structure, can be integrally formed in a net size, has the distribution characteristic of multi-axial fiber reinforcement, so that the fiber-reinforced composite core has more outstanding comprehensive properties of tensile resistance, compression resistance, bending resistance, torsion resistance and the like, simultaneously has dynamic fatigue and impact resistance, has excellent comprehensive mechanical properties, and has the advantages of high integral structure forming degree, outstanding profile design capability, strong multi-axial property designability, firmness, toughness and light weight.

Drawings

Fig. 1 is a schematic structural view of a fiber-reinforced composite core obtained by a manufacturing method of a fiber-reinforced composite core according to an embodiment of the present invention.

Fig. 2 is a schematic view of a partial structure of a three-dimensional preform in the fiber-reinforced composite core shown in fig. 1.

Fig. 3 is a schematic side view of the three-dimensional preform in the fiber-reinforced composite core shown in fig. 1.

Fig. 4 is a schematic structural view of a three-dimensional textile machine used in the manufacturing method of the fiber-reinforced composite core according to the embodiment of the present invention.

Fig. 5 is a schematic structural view of a fiber bundle preforming and bundling apparatus used in the method for manufacturing the fiber-reinforced composite core according to the embodiment of the present invention.

FIG. 6 is a schematic cross-sectional structure of a three-dimensional preform in the fiber-reinforced composite core shown in FIG. 1.

Fig. 7 is a schematic cross-sectional structure of the fiber reinforced composite core shown in fig. 1.

FIG. 8 is a process flow diagram of a method of manufacturing a fiber reinforced composite core of an embodiment of the present invention.

Fig. 9 is a schematic structural view of a preforming device used in the manufacturing method of the fiber-reinforced composite core according to the embodiment of the invention.

Fig. 10 is a schematic view of the structure of a compression device used in the method of manufacturing a fiber-reinforced composite core according to the embodiment of the present invention.

Fig. 11 is a schematic structural view of a sizing die used in the method of manufacturing a fiber-reinforced composite core according to the embodiment of the present invention.

Wherein the reference numerals are as follows:

100. three-dimensional preform

101. Warp yarn

102. 102a weft yarn

200. Resin composition

201. Resin surface layer

202. Resin filling layer

300. Three-dimensional weaving machine

301. Reed

302. Area of cloth yarn

400. Fiber bundle preforming bundling device

1. Creel

2. Three-dimensional preform forming device

3. Preforming device

31. Preformed opening and closing part

32. Preforming cavity

32a preformed straight section

32b preformed flare section

4. Preheating device

5. Compression device

51. Compression opening and closing part

52. Compression chamber

52a compressed straight section

52b compression flare section

53. First resin injection port

6. Shaping device

61. Shaping die

62. Fixed cavity

63. Second resin injection port

64. Mixing head

7. Traction machine

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and are not intended to limit the present invention.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the prior art, in order to make up for the deficiency of the circumferential performance of the unidirectional fiber pultrusion composite core, a winding layer/a braiding layer is added on the outer circumferential side of the shaft core prepared by the unidirectional fiber pultrusion process by adopting a winding and braiding process in a layer-by-layer overlapping mode to make up for the deficiency, and if one layer is added, the addition of multiple layers is considered. However, no matter how many layers are added, the final formed core-skin structure cannot avoid the separation of the skin and core interface when the composite core is damaged, and the skin layer is difficult to effectively inhibit the crack damage diffusion in the core layer to cause the rapid failure of the composite core, so the comprehensive mechanical property is not good.

In order to overcome the defects of a skin-core structure, the invention provides the fiber reinforced composite core with the integral structure, the fibers in the composite core form the integral structure which is complete, not layered and has no skin-core structure, the fiber reinforced composite core with the integral structure has more outstanding comprehensive properties of tensile resistance, compression resistance, bending resistance, torsion resistance and the like, and can have dynamic fatigue and impact resistance, thereby having more excellent comprehensive mechanical properties.

In other composite materials except for the composite core, a three-dimensional prefabricated body with an integral structure is used as a composite material reinforcement in the prior research, but the process modes of the composite materials are all sectional preparation, namely, a certain number of products are prepared at one time by one mold, and then the products are prepared repeatedly in multiple batches, so that the manufacturing cost is high, and the production efficiency is low. The pultrusion of the composite core is a technological mode which is few in the field of composite materials, can be continuously prepared, has outstanding mechanical properties in the pultrusion direction of products and extremely high quality consistency, and is very suitable for the requirements of industrialization, low cost and high quality. However, in the existing research, researchers of the pultrusion process of the composite core have too much attention to the improvement of a certain single directional performance of the composite core, and researchers of other process directions of composite materials have too much attention to the optimization of the manufacturing cost and the production efficiency of the segmented batch preparation mode of the three-dimensional preform, and because the existing composite core forms the winding layer and the woven layer as the reinforcement by winding and braiding processes, the molding mechanism is simple, the structure is not complex, and the control on equipment control, manufacturing quality control and particularly the control on the resin infiltration degree are easier compared with the three-dimensional preform, the research on the composite core in the prior art still focuses on the improvement of the structural performance of the sheath core, and the research on the composite core in the prior art does not consider that the three-dimensional preform is used in the preparation of the composite core to replace the sheath core structure to improve the comprehensive mechanical performance of the composite core, which is a technical bias existing in the technical field of the preparation of the composite core.

The invention overcomes the technical prejudice, and combines the three-dimensional prefabricated body molding and the composite core pultrusion molding process to obtain the fiber reinforced composite core with an integral structure. The three-dimensional preform has the characteristics of strong designability, outstanding comprehensive performance (particularly in the aspects of delamination resistance, impact resistance, fatigue resistance and the like), high added value, high manufacturing cost (mainly because of large waste in segmented manufacturing), and the like, and the continuous preparation of the composite core pultrusion process accurately offsets the problem of high manufacturing cost of the three-dimensional preform. The composite core with more excellent comprehensive mechanical properties can be obtained, and the forming of the three-dimensional preform is combined with the pultrusion process of the composite core to form a continuous preparation process, so that the manufacturing cost and the production efficiency can be effectively and reasonably controlled, and the characteristics of continuity, low cost, high efficiency and high quality control of the pultrusion process of the composite core and the characteristics that the three-dimensional preform can effectively improve the comprehensive properties of interlayer shear resistance, impact resistance, fatigue resistance and the like and can be integrally molded in net size are fully exerted.

Furthermore, most of the existing composite core resin infiltration modes are slotted resin baths, the resin infiltration degree is greatly influenced by resin fluidity and infiltration time, when the three-dimensional preform molding and the composite core pultrusion molding process are combined, if the slotted resin baths are adopted, because the internal structural form of the three-dimensional preforms is complex, the resin is difficult to infiltrate into the three-dimensional preforms by the self-fluidity, a large number of air holes can be generated in the insufficiently infiltrated three-dimensional preforms, and the performance of the composite cores is seriously influenced. In order to solve the problem of the resin infiltration degree in the three-dimensional preform, the invention provides the application of resin injection infiltration to the three-dimensional preform in the composite core pultrusion process. The resin injection infiltration technology is originated from the technical field of plastic extrusion, liquid resin is injected into a cavity of a mold with a target size containing fibers in a pressurizing mode through an independent machine, high-quality resin infiltration is achieved by utilizing conditions such as high pressure, a certain cavity structure, an injection port position and good sealing performance, and the resin infiltration technology is widely applied to the field of preparing composite materials in a segmented and batched mode, and the resin infiltration technology is not applied to the technical field of continuous composite core pultrusion processes due to the fact that the requirements of the implementation conditions of an injection system on sealing, pressure, injection quantity and the like are high. In order to solve the problem that the conventional slotted resin bath is difficult to thoroughly infiltrate the three-dimensional prefabricated body, the invention combines the resin injection infiltration process and the composite core pultrusion process, thereby forming a process system for continuously preparing the fiber reinforced composite core with the integral structure by three-dimensional prefabricated body molding, resin injection infiltration and pultrusion.

Based on this, the present invention provides a method of manufacturing a fiber-reinforced composite core for preparing a fiber-reinforced composite core having an integral structure.

Fig. 1 to 11 show an embodiment of a method for manufacturing a fiber-reinforced composite core according to the present invention.

Referring to fig. 1, the manufacturing method of the fiber-reinforced composite core of the present embodiment includes the following steps in order.

Step one, regularly and alternately interlocking a plurality of fiber bundles to form a three-dimensional prefabricated body 100, wherein the three-dimensional prefabricated body 100 is a three-dimensional fabric, the three-dimensional prefabricated body 100 is formed with an internal structure and an external outline which are interwoven into a whole, and the three-dimensional prefabricated body 100 is a non-layered integral structure.

And step two, preprocessing the three-dimensional preform 100.

And step three, performing resin 200 infiltration and pultrusion on the pretreated three-dimensional preform 100 to form the fiber reinforced composite core.

The fiber bundle, the three-dimensional preform 100 and the fiber reinforced composite core are drawn and advanced by the same drawing force, and the first step to the third step are continuously performed under the action of the drawing force.

The manufacturing method of the fiber reinforced composite core of the embodiment combines the three-dimensional preform 100 molding with the composite core pultrusion process, and fully exerts the characteristics of continuity, low cost, high efficiency and high quality control of the composite core pultrusion process, and the characteristics that the three-dimensional preform 100 can effectively improve the comprehensive properties of interlayer shear resistance, impact resistance, fatigue resistance and the like and can be integrally molded in net size. The three-dimensional preform 100 is an integral structure which is formed by fiber bundles completely and is not layered and has no skin-core structure, can be integrally formed in a net size, has the distribution characteristic of multi-axial fiber reinforcement, enables the fiber-reinforced composite core to have more outstanding comprehensive properties of tensile resistance, compression resistance, bending resistance, torsion resistance and the like, simultaneously has dynamic fatigue and impact resistance, is excellent in comprehensive mechanical property, and has the advantages of high integral structure forming degree, outstanding profile modeling design capability, strong multi-axial property designability, firmness, toughness and light weight.

In this embodiment, preferably, in the first step, continuous fiber bundles distributed along the circumferential direction are arranged on the outer contour of the three-dimensional preform 100. The continuous fiber bundles are formed as a part of the outer contour of the three-dimensional preform 100, play a role in restraining the internal structure of the three-dimensional preform 100, and are interwoven with the internal structure of the three-dimensional preform 100 into a whole without forming a sheath-core structure.

In step one, the three-dimensional preform 100 is preferably prepared using a three-dimensional weaving process. During preparation, the fiber bundles are used as yarns, and the integrated net-size forming of the three-dimensional preform 100 can be realized through the technical combination of yarn opening configuration, yarn specification configuration, weft yarn continuous weaving and the like, so that the obtained three-dimensional preform 100 has the basic net-size contour of the target composite core. It should be noted that the three-dimensional weaving process is an existing mature process, but when the three-dimensional preform 100 is prepared in the manufacturing method of the fiber reinforced composite core according to the present embodiment, in order to facilitate resin infiltration and pultrusion of the three-dimensional preform 100, a certain optimization and adjustment may be performed on the three-dimensional weaving process to obtain a three-dimensional preform 100 that is infinitely close to a round rod shape and has a relatively uniform internal structure.

Specifically, the structure of the three-dimensional preform 100 obtained by shaping the fiber bundle by the three-dimensional weaving process is shown in fig. 2 and 3. The fiber bundles are divided as yarns into warp yarns 101 and weft yarns 102, the warp yarns 101 extending in the pultrusion direction (warp direction) of the composite core, and the weft yarns 102 extending in a direction (weft direction) perpendicular to the warp direction in the horizontal plane. In the three-dimensional weaving process, warp yarns 101 are overlapped with weft yarns 102 of different layers in a bending mode, and the cross sections of the weft yarns 102 are stacked after regular circulation, so that an integral structure of layer-by-layer interlocking is realized, and the three-dimensional prefabricated body 100 is obtained. In practice, warp yarn 101 and weft yarn 102 are curved with respect to each other, but warp yarn 101 is less curved than weft yarn 102 because warp yarn 101 is more pulled. The overall structure of the three-dimensional preform 100 can be freely designed by changing the number of the yarn bending points and the span of the yarn bending points, the fewer the yarn bending points are, the larger the span of the yarn bending points are, the stronger the deformability of the three-dimensional preform 100 is, and the better the mechanical performance in the extending direction of the yarn is. The three-dimensional weaving machine 300 is an apparatus for regularly and alternately interlocking warp yarns 101 and weft yarns 102 in a three-dimensional weaving process, and is a conventional apparatus, and a schematic structure thereof is shown in fig. 4, and in operation, yarns (fiber bundles) are formed after passing through harness holes and a reed 301 of the three-dimensional weaving machine 300. The heddle holes of the existing three-dimensional textile machine 300 are arranged in a spatial rectangle, the heddle holes of the three-dimensional textile machine 300 move up and down, the upward movement can drive the fiber bundles to be lifted, the lifted fiber bundles and the fiber bundles which are not lifted form a triangular opening, after the weft yarns 102 are introduced into the triangular opening, the reed 301 pushes the weft yarns 102 into the triangular opening to be tightened, then the lifted fiber bundles descend, the original fiber bundles which are not lifted are lifted, and the cross interlocking structure among the fiber bundles is formed in a repeated way. In this embodiment, the heddle holes of the three-dimensional weaving machine 300 are preferably designed to be inclined forward and backward and inclined leftward and rightward so as to reduce the frictional force between the yarns. In this embodiment, a fiber bundle preforming and bundling device 400 is provided at the rear side of the cloth yarn region 302 at the rear end of the three-dimensional weaving machine 300, and as shown in fig. 5, the fiber bundle preforming and bundling device 400 is provided with a plurality of grids, each grid can restrain one fiber bundle, and each grid corresponds to a heddle hole of the three-dimensional weaving machine 300 one by one. According to the parameter requirements of the diameter of a target composite core, the volume content of fibers, the linear density and the bulk density of fiber raw materials and the like, the number of needed fiber bundles can be calculated, a square grid is formed on the fiber bundle preforming bundling device 400 after the diameter of the target composite core and the distribution point position of warp yarns of a three-dimensional weaving machine are comprehensively considered, a circle is made in the square grid by combining the usage of the fiber bundles, an area within the circle is used as a yarn distribution area, the fiber bundles with the needed number are uniformly distributed in the circle, the fiber bundles are firstly distributed in complete single grids in the circle in a penetrating manner, the fiber bundles are distributed in grids with the area within the circle exceeding two thirds of the area of the single grids at the edge of the circle in a penetrating manner, and the fiber bundles are not distributed in grids with the area within the circle less than one third of the area of the single grids. Placing a fiber bundle preforming bundling device 400 at the rear side of a cloth yarn area 302 of a three-dimensional weaving machine 300 at the stage of forming a three-dimensional preform at the beginning of a fiber bundle, wherein the fiber bundle passes through a harness wire hole and a reed 301 of the three-dimensional weaving machine 300 and then passes through the fiber bundle preforming bundling device 400 to be restrained in the cloth yarn area on a square grid of the fiber bundle preforming bundling device 400, and the fiber bundle preforming bundling device 400 synchronously advances with a pulled fiber bundle at the rear side of the three-dimensional preform 100 when the fiber bundle is formed into the three-dimensional preform 100 by the three-dimensional weaving machine 300; as the forming length of the three-dimensional preform 100 before the fiber bundle preforming and bundling device 400 is increased, after the fiber bundle not participating in the forming and the formed three-dimensional preform part 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, so that the fiber bundle preforming and bundling device 400 exits from the fiber bundle advancing path, the formed three-dimensional preform 100 can smoothly enter the next process, and the three-dimensional weaving machine 300 continuously forms the three-dimensional preform 100 under the traction force. Therefore, the fiber bundle preforming bundling device 400 performs the preforming bundling function on the initial forming of the fiber bundles, can ensure the straightness and the contour forming quality of the three-dimensional preform 100, improves the circular matching degree of the outer contour of the three-dimensional preform 100 and the target composite core, and can obtain the three-dimensional preform 100 with the shape close to the shape of the target composite core.

Fig. 6 shows a threading form on the cross-sectional structure of the three-dimensional preform 100 formed by a three-dimensional weaving process, and weft yarns 102a are arranged on the outer contour of the three-dimensional preform 100 along the circumferential direction, and the weft yarns 102a are continuous fiber bundles arranged on the outer contour of the three-dimensional preform 100 along the circumferential direction. The continuous weft yarns 102a interlock different warp yarn layers and form a process mode of fiber binding along the circumferential direction on the surface layer, the weft yarns 102a extend along different directions, the paths of the weft yarns 102a are uninterrupted after bypassing the warp yarns 101 arranged at the circular edges, the warp yarns 101 are restrained by a continuous weft yarn 102a structure along the circumferential direction of the three-dimensional preform 100 in a winding-like form, the integration and non-layering of the internal structure and the external contour of the three-dimensional preform 100 are further realized, and a weft yarn closed loop structure formed at the edges of different warp yarn layers is one of the bases for the integrated forming of the three-dimensional preform 100. In particular, in practice, at the round edge warp yarn arrangement point, a fine tensile yarn may be additionally added or the tension of the round edge point warp yarn may be increased to improve the molding quality of the three-dimensional preform 100.

Fig. 7 shows a cross-sectional structure of a fiber reinforced composite core having an integral structure prepared from a three-dimensional preform 100 formed by a three-dimensional weaving process, when the three-dimensional preform 100 is impregnated with a resin 200 after forming, fiber bundles on the outer contour surface of the three-dimensional preform 100 are covered with the resin 200 to form a resin surface layer 201, and the resin 200 enters the inner space of the three-dimensional preform 100 to fill the gaps between the fiber bundles to form a resin filling layer 202. The three-dimensional preform 100 impregnated with the resin 200 is subjected to pultrusion curing molding to obtain the fiber-reinforced composite core with an integral structure.

In fig. 6 and 7, in order to show the layers of the warp yarn 101, the weft yarn 102, and the resin 200, the layers are respectively shown by an oval cross section, a solid line, and a broken line, and in practical use, the warp yarn 101 and the weft yarn 102 are both fiber bundles in irregular ribbon shapes, and after regular alternating interlocking, the fiber bundles are approximately oblate-like shapes. When the three-dimensional preform 100 is pultruded, the fiber bundles move relatively to fill the larger voids in the internal structure of the three-dimensional preform 100, and further fill all voids with the resin 200. In order to distinguish the layers of the warp yarn 101, the weft yarn 102 and the resin 200, the limits and positions of the warp yarn 101, the weft yarn 102 and the fiber bundles and the resin 200 distributed circumferentially on the outer contour are enlarged to make the display clearer.

In this embodiment, the fiber bundle may be any one or a combination of a plurality of carbon fibers, glass fibers, ultra-high molecular weight polyethylene fibers, aramid fibers, polyimide fibers, PBO fibers (short for poly-p-phenylenebenzobisoxazole fibers), hybrid fibers (a plurality of different fibers are mixed), modified fibers (for example, fibers with certain properties improved by introducing carbon nanotubes, toughening particles, and the like into a surface layer of a certain existing fiber), and plant fibers (for example, lignin fibers). The fiber-reinforced composite core of the present embodiment is mainly used for cables, and therefore the fiber bundles used therein are mainly carbon fibers.

Referring to fig. 8, in the first step of the method for manufacturing a fiber reinforced composite core according to the present embodiment, when a three-dimensional preform 100 is manufactured by a three-dimensional weaving process, specifically, a fiber bundle is placed on a creel 1 in a wound state wound on a bobbin, and is drawn, the fiber bundle is unwound from the bobbin in a single bundle state, and is introduced into a three-dimensional preform forming apparatus 2 through a ceramic eye, the three-dimensional preform forming apparatus 2 includes a three-dimensional weaving machine 300 and a fiber bundle pre-forming and bundling device 400, the fiber bundle is formed into a three-dimensional preform 100 having a shape close to a target composite core shape after passing through a harness hole and a reed 301 of the three-dimensional weaving machine 300, the fiber bundle pre-forming and bundling device 400 is placed at a rear side of a yarn distribution area 302 of the three-dimensional weaving machine 300 at an initial stage of forming, the fiber bundle is pre-formed and is pre-bundled, and after forming a length of the three-dimensional preform is formed, the fiber bundle not participating in forming and the formed three-dimensional preform part can be drawn through a subsequent path and by a drawing force, the fiber bundle advancing and the fiber bundle pre-forming device 400 is removed from the pre-forming and the pre-forming path. Thereby achieving integral net shape forming of the three-dimensional preform 100 and providing the resulting three-dimensional preform 100 with a substantially net shape profile of the target composite core.

In this embodiment, preferably, in the second step, the pre-processing includes primary molding, preheating, and secondary molding, the primary molding performs primary compression on the three-dimensional preform 100 obtained in the first step, the preheating performs preheating on the three-dimensional preform 100 after the primary molding, and the secondary molding performs secondary compression on the preheated three-dimensional preform 100.

Wherein the primary shaping can be done by means of a preforming device 3. Referring to fig. 9, in the present embodiment, preferably, the preforming device 3 includes two preforming openers 31 disposed opposite to each other in a separable or joinable manner along the compression direction a of one compression, a through preforming cavity 32 is formed between the two joined preforming openers 31, and the preforming cavity 32 includes a preforming straight section 32a having a diameter smaller than the outer contour diameter of the three-dimensional preform 100 and a preforming flared section 32b having a gradually increasing diameter extending from both ends of the preforming straight section 32 a. When the three-dimensional preform 100 passes through the preform cavity 32 of the preform device 3, the two preform open-close portions 31 are regularly and separately joined, and the three-dimensional preform 100 is molded into a more uniform target diameter by the preform straight section 32a of the preform cavity 32. The opening and closing speed of the preforming device 3 is matched with the advancing speed of the three-dimensional preform 100, so that the length of each pressing can be overlapped end to end, and omission is avoided. The length of the preform cavity 32 of the preforming device 3 is related to the target diameter, and the larger the target diameter is, the longer the preform cavity 32 is and the higher the opening and closing force points are, so as to ensure the uniform compression force. The preform flared sections 32b at the ends of the preform cavity 32 may facilitate the introduction and removal of the three-dimensional preform 100 into and out of the preform cavity 32. Preferably, the two preformed flared sections 32b and the preformed straight section 32a are smoothly connected by a chamfer to avoid damage to the three-dimensional preform 100 due to sharp edges or corners and avoid large indentations. Preferably, the walls of preform cavity 32 are coated to improve the wear resistance of preform cavity 32 and reduce the coefficient of friction.

The preheating may be accomplished by a preheating device 4. The preheating device 4 may adopt an existing conventional heating device.

The secondary molding may be accomplished by a compression device 5. Referring to fig. 10, in the present embodiment, preferably, the compressing device 5 includes two compressing open-close portions 51 which are oppositely disposed in a separable or joinable manner along the compressing direction B of the secondary compression, a through compressing cavity 52 is formed between the two joined compressing open-close portions 51, and the compressing cavity 52 includes a compressing straight section 52a having a diameter not greater than the outer contour diameter of the three-dimensional preform 100 after the primary compression and compressing flared sections 52B having a gradually increased diameter and extending from both ends of the compressing straight section 52 a. 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 and separately jointed, the three-dimensional preform 100 is subjected to second-order molding with a target diameter through the compression straight section 52a of the compression cavity 52, and the abundant elastic relaxation space in the three-dimensional preform 100 is further compressed, so that the fiber volume content and the molding quality of the final composite core are ensured, and the shape of the three-dimensional preform 100 is approximate to the shape of the target composite core. The opening and closing speed of the compression device 5 is matched with the advancing speed of the three-dimensional prefabricated body 100, so that the length of each pressing can be overlapped end to end, and omission is avoided. The length of the compression chamber 52 of the compression device 5 is related to the target diameter, and the larger the target diameter is, the length of the compression chamber 52 is preferably increased and the opening and closing force applying point is increased to ensure the uniform compression force. The compression flare sections 52b at both ends of the compression chamber 52 may facilitate the introduction and discharge 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 a chamfer, so as to avoid the damage to the three-dimensional preform 100 caused by the existence of sharp edges or corners and avoid the generation of large indentations. Preferably, the walls of the compression chamber 52 are provided with a wear resistant and anti-stick coating to improve wear resistance and reduce the coefficient of friction of the compression chamber 52.

Further, in the second step, the resin may be pre-impregnated into the preheated three-dimensional preform 100 while performing the secondary molding, and the resin pre-impregnation is preferably performed by impregnating the three-dimensional preform 100 by resin pressure injection. The secondary molding and resin pre-preg may be accomplished by a compression device 5. Referring to fig. 10, in a preferred embodiment, at least one compression opening 51 of the compression device 5 is provided with a first resin injection port 53 communicated with the compression chamber 52, and the first resin injection port 53 is used for injecting resin into the compression chamber 52. The first resin injection port 53 is connected to a resin injection system, which is an existing apparatus, and a resin recovery device may be provided below the compression device 5 to receive excess resin extruded from the compression device 5. In each opening and closing process of the compression device 5, resin injection is completed from the first resin injection port 53 to the compression cavity 52, the resin is infiltrated into the three-dimensional preform 100 under the injection pressure, and the resin is gradually diffused in the three-dimensional preform 100 by means of the closing compression force, the capillary effect and the like of the compression device 5 to form primary infiltration, and the redundant resin is extruded out of the compression device 5, is recovered and filtered by a recovery device below the compression device 5 and then returns to a resin injection system, so that secondary molding and resin pre-infiltration of the three-dimensional preform 100 are realized. Preferably, the two compression opening and closing portions 51 are respectively provided with a first resin injection port 53, the two first resin injection ports 53 are respectively located at two end portions of the compression straight section 52a and are arranged in an alignment manner along the compression direction B of the secondary compression, and the two first resin injection ports 53 arranged in the alignment manner can realize thorough infiltration of the three-dimensional preform 100 and slow down overflow of resin from the fracture of the compression device 5 by pressure hedging.

Thus, in the second step, the shape of the three-dimensional preform 100 after the secondary molding and the resin pre-impregnation is similar to the target shape of the fiber reinforced composite material, and the resin 200 is diffused in the internal structure of the three-dimensional preform 100 after the secondary molding and the resin pre-impregnation to form the resin primary impregnation.

In this embodiment, preferably, in the second step, a compression direction a of the three-dimensional preform 100 by the preforming device 3 and a compression direction B of the three-dimensional preform 100 by the compressing device 5 are perpendicular to each other, and preferably, the compression direction a of the first compression is a horizontal direction and the compression direction B of the second compression is a vertical direction. The compression direction of the two-time molding is vertical, so that indentation deformation can be neutralized, and the cross section of the three-dimensional preform 100 after the two-time molding is fuller.

In this embodiment, the resin infiltration in step three is preferably performed by infiltrating the three-dimensional preform 100 by resin pressure injection.

The resin impregnation and pultrusion of the pretreated three-dimensional preform 100 in step three can be accomplished by the sizing device 6. Referring to fig. 8 and 11, the shaping device 6 includes a shaping mold 61, a shaping cavity 62 penetrating along a traction direction of the traction force is formed inside the shaping mold 61, a second resin injection port 63 communicating with the shaping cavity 62 and a high temperature curing region heating the inside of the shaping cavity 62 are provided on the shaping mold 61, the second resin injection port 63 is used for injecting resin into the shaping cavity 62, and the high temperature curing region is located on a 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 longer length, and one end of the shaping cavity 62 close to the compressing device 5 is provided with a flared bell mouth shape, so that the pretreated three-dimensional preform 100 can enter the shaping cavity 62 of the shaping mold 61. The three-dimensional preform 100 after the pre-treatment and the secondary compression molding by the compression device 5 can enter the shaping mold 61 of the shaping device 6 more easily. The second resin injection port 63 may be connected to a resin injection system, which is an existing apparatus, through a mixing head 64. When the pretreated three-dimensional preform 100 passes through the shaping cavity 62 of the shaping mold 61, the resin in the resin injection system is defoamed for the first time under ultrasonic waves, and is injected into the shaping cavity 62 through the second resin injection port 63 at high pressure to complete the final injection and infiltration of the three-dimensional preform 100, preferably, an ultrasonic emitter is arranged outside a resin infiltration area of the shaping mold 61 where the second resin injection port 63 is located, and after a certain frequency is set, the ultrasonic waves penetrate through the three-dimensional preform 100 and the infiltrated resin, so that the defoaming of the resin injected into the three-dimensional preform 100 can be further promoted, and the porosity of the inner part of the composite core is reduced. And finally, heating the three-dimensional preform 100 after being soaked in the resin through a high-temperature curing area to cure and form the three-dimensional preform 100 soaked in the resin, and finally drawing the three-dimensional preform out of the shaping mold 61 to obtain the fiber reinforced composite core with the integral structure. Preferably, a collecting system for collecting the composite core may be disposed on a side of the shaping mold 61 away from the compressing device 5, and the composite core drawn out from the shaping mold 61 is collected by the collecting system after being cooled, and the collecting mode is preferably coil collection.

In this embodiment, the resin 200 impregnated in the three-dimensional preform 100 may be any one or a combination of a thermoplastic resin and a thermosetting resin (for example, toughening particles of a thermoplastic resin are added to a thermosetting resin).

Referring to fig. 8, in the method for manufacturing the fiber-reinforced composite core of the present embodiment, a traction force pulled from the creel 1 to the collection system may be provided by the traction machine 7 to pull the fiber bundle, the three-dimensional preform 100, and the composite core to advance, so that the steps one to three are continuously performed under the traction force. Specifically, the traction machine 7 sequentially pulls the fiber bundles on the creel 1 to form the three-dimensional preform 100 through the three-dimensional preform forming device 2 (the three-dimensional textile machine 300 and the fiber bundle preforming and bundling device 400), pulls the three-dimensional preform 100 to form the fiber reinforced composite core through the preforming device 3, the preheating device 4, the compression device 5 and the shaping device 6 sequentially, pulls the fiber reinforced composite core out of the shaping device 6 to enter the collection system after cooling, so that a three-dimensional preform forming-resin injection infiltration-pultrusion continuous preparation process system is formed, and the fiber reinforced composite core with an integral structure can be prepared.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims (7)

1. A method of manufacturing a fibre-reinforced composite core, comprising the steps of, in order:

the method comprises the following steps that firstly, a plurality of fiber bundles are regularly and alternately interlocked to form a three-dimensional prefabricated body, the three-dimensional prefabricated body is a three-dimensional fabric, the three-dimensional prefabricated body is formed into an internal structure and an external outline which are interwoven into a whole, and the three-dimensional prefabricated body is of a non-layered integral structure;

step two, preprocessing the three-dimensional prefabricated body;

step three, performing resin infiltration and pultrusion on the pretreated three-dimensional prefabricated body to form a fiber reinforced composite core;

the fiber bundle, the three-dimensional prefabricated body and the fiber reinforced composite core are drawn and advanced by the same drawing force, and the steps from the first step to the third step are continuously carried out under the action of the drawing force.

2. The method of manufacturing a fiber-reinforced composite core according to claim 1, wherein in step one, continuous fiber bundles distributed in a circumferential direction are arranged on an outer contour of the three-dimensional preform.

3. The method of manufacturing a fiber reinforced composite core according to claim 1, wherein in the first step, the three-dimensional preform is prepared using a three-dimensional weaving process.

4. The method of manufacturing a fiber-reinforced composite core according to claim 1, wherein in the second step, the pre-treatment includes a primary molding that primarily compresses the three-dimensional preform obtained in the first step, a pre-heating that pre-heats the once-molded three-dimensional preform, and a secondary molding that secondarily compresses the pre-heated three-dimensional preform.

5. The method of manufacturing a fiber-reinforced composite core according to claim 4, wherein in the second step, a compression direction in which the primary molding primarily compresses the three-dimensional preform and a compression direction in which the secondary molding secondarily compresses the three-dimensional preform are perpendicular to each other.

6. The method of manufacturing a fiber-reinforced composite core according to claim 4, wherein in the second step, the shape of the three-dimensional preform after the secondary molding approximates the target shape of the fiber-reinforced composite core.

7. The method of manufacturing a fiber-reinforced composite core according to claim 1, wherein in the third step, the resin infiltration is performed by infiltrating a three-dimensional preform with resin by pressure injection.

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