A three-dimensional braided preform, its preparation method and preparation device

Abstract

The present invention belongs to the field of three-dimensional weaving technology, and relates to a three-dimensional weaving preform, and a preparation method and preparation device thereof. A preparation device for a three-dimensional weaving preform includes a chassis, an angle wheel, a dial and a weaving yarn carrier, the weaving yarn carrier includes a weaving yarn carrier base and a weaving yarn carrier straight rod, the angle wheel, the dial and the weaving yarn carrier base are all multiple, the angle wheel is a six-cut circular plate, and the dial is a two-cut circular plate. A preparation method for a three-dimensional weaving preform adopts a preparation device for a three-dimensional weaving preform as described above. A three-dimensional weaving preform is prepared using a preparation method for a three-dimensional weaving preform as described above. The weaving nodes on the surface of the three-dimensional weaving preform prepared by the present invention are more evenly distributed, coherent and dense, and the surface unevenness is relatively smaller. The composite material prepared using this three-dimensional weaving preform is relatively more evenly stressed when subjected to external loads, and is not easily damaged and failed quickly due to stress concentration.

Description

Technical Field

[0001] The present invention belongs to the technical field of three-dimensional braiding, and relates to a three-dimensional braided preform, a preparation method thereof, and a preparation device thereof. Background Art

[0002] High-performance fiber-reinforced composites can replace traditional metal materials due to their high strength, low density, high modulus, fatigue resistance, corrosion resistance, high temperature resistance, low coefficient of thermal expansion, etc. As load-bearing structures, they are widely used in the fields of aerospace, transportation, wind power, pressure vessels, etc. Load-bearing structures are generally divided into three categories according to their geometric shapes: rod structures, shell structures, and solid structures. Among them, the rod structure is characterized in that the axial dimension is much larger than the cross-sectional dimension. Its structure is relatively simple, easy to design and manufacture, and has high preparation efficiency. It is mostly prepared by the pultrusion process and is commonly found in various equipment and facilities. At present, the application of high-performance fiber composites in rod structures is mostly based on hollow rods, such as unmanned aerial vehicle wing frames, drive shafts, and oil drill pipes. For some large-size cable-type, core-type or rod-type components with complex load environments where the hollow rod structure cannot meet the requirements, the use of solid composite rod structures is particularly necessary, such as composite cores such as tension cables, overhead line composite cores, marine cable reinforcements, pusher rods, and structural battery electrodes. However, at present, solid round rod composites are mostly prepared by pultrusion, pultrusion & winding, and pultrusion & braided tube processes. Most of the internal fibers are arranged parallel to the axis. The static mechanical properties in other directions except the axial direction are not fully utilized, and the dynamic mechanical properties are almost non-existent. In addition, although the winding and braiding processes have a winding layer or a braided tube layer to wrap the axial fibers, a "skin-core structure" is formed, and the "skin" layer is difficult to effectively restrain the crack propagation in the "core" layer structure, resulting in poor dynamic mechanical properties.

[0003] A three-dimensional braided preform is an integral structure formed by the spatial overlapping and interlocking of fibers, and has the characteristic of no delamination. The braiding nodes in the three-dimensional braided preform can form an effective physical barrier to crack propagation, enabling the excellent performance of the dynamic mechanical properties of the composite material. The three-dimensional braided preform can make the composite material take into account both static and dynamic mechanical properties. Therefore, the round rod composites formed by using the three-dimensional braided preform are expected to solve many problems faced by the above-mentioned composites with skin-core structures.

[0004] Patent CN114990778B discloses a three-dimensional braided preform, the structure of which is as Figure 1 shown. Its preparation method is as follows: arrange three 3-notch angle wheels intersecting each other, respectively arrange yarn storage spindles on the yarn carriers of the angle wheels, and make the three intersecting 3-notch angle wheels move towards each other. Continuous braiding can obtain the preform. The following technical problems exist in this preparation method:

[0005] (1) Affected by the forming mechanism, the three-dimensional braided preform has an "I-shaped" or "rectangular" outer contour with angular structures. When the obtained composite material is subjected to external loads, stress concentration is likely to occur at the corners, leading to rapid damage and failure.

[0006] (2) Limited by the design and layout of the corner wheels, the three-dimensional braided preform cannot be formed into a round rod-shaped structure, and the structure cannot be scaled proportionally.

[0007] (3) The structural designability of the three-dimensional braided preform is not strong. The entire structure of the three-dimensional braided preform cannot achieve independent control of the presence or absence of braiding nodes, and it is impossible to conduct differential design of structure and performance within a single three-dimensional braided preform.

[0008] (4) The distribution of braiding nodes in the three-dimensional braided preform is less and uneven on the surface. Due to the lack of the advantage of multi-layer tight interlocking, and there are two structural holes in the center of the structure due to the gap of the corner wheels, the overall structure of the three-dimensional braided preform will be relatively loose, the fiber content is not high, and the static and dynamic performance of the obtained composite material is not fully exerted.

[0009] These above problems have hindered the application of three-dimensional braided preforms in the forming of round rod-like composite materials. Therefore, it is necessary to develop a new three-dimensional braided preform to solve the above problems. Summary of the Invention

[0010] The purpose of the present invention is to solve the above problems existing in the prior art, and provide a three-dimensional braided preform, its preparation method and preparation device.

[0011] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0012] A preparation device for a three-dimensional braided preform includes a chassis, corner wheels, a dial, and a braided yarn carrier. The braided yarn carrier includes a braided yarn carrier base and a braided yarn carrier straight rod. Each braided yarn carrier has a supporting braided yarn bobbin and a braided yarn unwinding auxiliary frame. The porcelain eye on the braided yarn unwinding auxiliary frame can be made of alumina material, and preferably titanium oxide material can reduce the friction coefficient and minimize the wear of carbon fibers. During use, first wind the yarn onto the braided yarn bobbin, then concentrically assemble the braided yarn bobbin and the braided yarn unwinding auxiliary frame onto the braided yarn carrier straight rod of the supporting braided yarn carrier, and then pass the yarn on the braided yarn bobbin through the porcelain eye on the side of the braided yarn unwinding auxiliary frame for bunching. The number of corner wheels, dials, and braided yarn carrier bases are all multiple. The corner wheel is a six-cut round plate, and the dial is a two-cut round plate.

[0013] The formation process of the six-notch circular plate is as follows: Select 6 regions a on the circular plate u that have the same shape, the same size, do not overlap with each other, and are evenly distributed around the central circumference of the circular plate u. The region a is enclosed by 2 arcs, and one of the arcs coincides with the edge of the circular plate u. After cutting off the 6 regions a to form 6 cuts, the six-notch circular plate is obtained;

[0014] The formation process of the two-notch circular plate is as follows: Select 2 regions b on the circular plate v that have the same shape, the same size, do not overlap with each other, and are evenly distributed around the central circumference of the circular plate u. The region b is enclosed by 2 arcs, and one of the arcs coincides with the edge of the circular plate v. After cutting off the 2 regions b to form 2 cuts, the six-notch circular plate is obtained;

[0015] The regions a, the regions b, and the bottom surface of the braided yarn carrier base have the same shape and size;

[0016] All the six-notch circular plates are distributed in n layers, where n ≥ 2. Each layer is numbered starting from 1 from the inside to the outside. The number of six-notch circular plates in the first layer is 1, and the number of six-notch circular plates in the i-th layer is 6×(i - 1), where 2 ≤ i ≤ n. Any two adjacent six-notch circular plates are arranged at intervals; the six-notch circular plates in the i-th layer are evenly distributed and the connecting lines of the center points form a regular hexagon. The vertices of the regular hexagons corresponding to the 2nd to nth layers are distributed on 6 lines radiating outward from the center point of the six-notch circular plate in the first layer;

[0017] Each cut of the six-notch circular plate is filled with 1 braided yarn carrier base; any two adjacent six-notch circular plates have one cut facing each other, and the braided yarn carrier bases in the two opposite cuts simultaneously fill the 2 cuts of 1 two-notch circular plate.

[0018] The preparation device of the three-dimensional braided preform of the present invention is different from the ordinary tube sleeve braiding machine. The path of each braided yarn carrier of the preparation device of the three-dimensional braided preform of the present invention can freely change between the inner and outer circles, enabling the braided yarn carrier to move between different circles and form a three-dimensional braided preform with a consistent inside and outside. The inside of the ordinary tube sleeve braiding machine is large-scale hollow, and there are only two paths of yarn interweaving movement. The braided yarn carrier weaves the hollow tube sleeve preform in an 8-shaped movement trajectory within the track, as Figure 19 shown;

[0019] The present invention uses a combination of a six-notch circular plate-shaped corner wheel and a two-notch circular plate-shaped dial. The corner wheel and the dial are arranged in a hexagonal layout. Affected by the forming mechanism, the cross-section of the three-dimensional braided preform has the characteristic of being approximately circularly symmetric. After the tension is released, the three-dimensional braided preform will relax, and its outer contour is approximately rod-shaped, without angular structures with stress concentration, which can effectively solve the technical problem that the composite material is prone to stress concentration and rapid damage failure when subjected to load due to the existence of angular structures in CN114990778B;

[0020] The corner wheel layout of the present invention is that six corner wheels are evenly distributed around the circumference of one corner wheel, and any two adjacent corner wheels do not intersect, so that the structure of the three-dimensional braided preform can be proportionally enlarged. After proportional enlargement, the structural forming mechanism and performance mechanism of the three-dimensional braided preform are consistent, and the performance is significantly improved. This can solve the technical problem that the preform structure of CN114990778B cannot be proportionally enlarged.

[0021] like Figure 18 As shown, the cooperative movement of the dial and the angle wheel of the present invention enables the yarn 1 to form a braiding node 2. The independently controllable dial and angle wheel allow the braiding node 2 in the three-dimensional braided preform to be freely controlled to be present or absent, thereby enriching the designability of the three-dimensional braided preform structure, and being able to provide a differentiated design of the structure and performance of a single three-dimensional braided preform, thereby solving the technical problem of the CN114990778B preform that it is impossible to perform differentiated design of the structure and performance within a single three-dimensional braided preform.

[0022] As the preferred technical solution:

[0023] As described above, a preparation device for a three-dimensional woven preform is provided with a lining yarn carrier on at least one corner wheel; each lining yarn carrier has a matching lining yarn spindle and a lining yarn withdrawal auxiliary frame, and the porcelain eye on the lining yarn withdrawal auxiliary frame can be made of aluminum oxide, preferably titanium oxide. When in use, the yarn is first wound onto the lining yarn spindle, and then the lining yarn spindle and the lining yarn withdrawal auxiliary frame are concentrically assembled to the lining yarn carrier straight rod of the matching lining yarn carrier, and then the yarn on the lining yarn spindle is passed through the porcelain eye on the side of the lining yarn withdrawal auxiliary frame for bundled; when the preparation device of the present invention is used to prepare a three-dimensional woven preform, the woven knots all appear at the dial position, and the area of the non-woven yarn carrier on the corner wheel will be missing yarn, which is manifested as holes in the woven structure of the cross-section of the three-dimensional woven preform. In order to fill the holes, the present invention adds a lining yarn carrier, and the axial lining yarn can be filled into the holes of the three-dimensional woven preform through the lining yarn carrier, thereby increasing the fiber volume content and strengthening the axial mechanical properties of the three-dimensional woven preform.

[0024] The device for preparing a three-dimensional braided preform as described above is provided with a lining yarn carrier on the corner wheel, the number of the lining yarn carrier is 1, and the lining yarn carrier is located at the center of the corner wheel.

[0025] As described above, a preparation device for a three-dimensional braided preform is provided with an angle wheel provided with lining yarn carriers, the number of the lining yarn carriers is greater than 1, and the lining yarn carriers are distributed in a circle around the central axis of the angle wheel.

[0026] A preparation device for a three-dimensional braided preform as described above. A circular slide rail is further provided on the corner wheel of the carrier for the backing yarn. The center of the circular slide rail is located on the central axis of the corner wheel. The carrier for the backing yarn is slidably connected to the circular slide rail. In this way, when the corner wheel rotates, the fibers on the carrier for the backing yarn can be maximally prevented from following the rotation of the corner wheel to generate torque, and the multi-strand fiber bundle can be maximally kept straight and bundled without being twisted. Specifically, the carrier for the backing yarn includes a base of the carrier for the backing yarn and a straight rod of the carrier for the backing yarn. The shape of the base of the carrier for the backing yarn is circular, and balls are embedded on both the peripheral surface and the bottom surface. With the assistance of lubricating grease, the base of the carrier for the backing yarn can smoothly slide on the circular slide rail. A circular through-hole is further provided on the corner wheel provided with the carrier for the backing yarn. The circular through-hole is used for the straight rod of the carrier for the backing yarn to pass through. The diameter of the circular through-hole is smaller than the width of the circular slide rail. In this way, the carrier for the backing yarn can be prevented from separating from the corner wheel.

[0027] A preparation device for a three-dimensional braided preform as described above. Each corner wheel has a supporting corner-wheel drive motor, and each dial has a supporting dial drive motor. Above the carrier for the braiding yarn, a pair of rollers is provided. Above the pair of rollers, a winding wheel is provided. During use, during the process of winding the yarn, the corner wheel moves under the control of the corner-wheel drive motor, and the dial moves under the control of the dial drive motor, resulting in the co-movement of the carrier for the braiding yarn and the braiding yarn spool and the braiding yarn unwinding auxiliary frame (or, there is also the carrier for the backing yarn and the backing yarn spool and the backing yarn unwinding auxiliary frame) supporting it. After the yarn is bundled, it first passes through a pair of rollers. The rollers have a radial clamping elastic force and can generate a certain clamping force on the bundled yarn to prevent the yarn bundle from loosening. Then, the yarn bundle is wound around the winding wheel a certain number of turns in the rotation direction of the winding wheel and fixed. By adjusting the braiding speed and the rotation speed of the winding wheel, the tension control of the three-dimensional braided preform can be realized, so that the three-dimensional braided preform can always remain straight and formed and be wound during the braiding process.

[0028] A preparation device for a three-dimensional braided preform as described above. Above the carrier for the braiding yarn, a metal bundling ring is provided. The metal bundling ring is located below the pair of rollers and is grounded. Specifically, the bundling ring can be made of stainless steel and can be embedded in a metal frame. The metal frame is connected to the metal main body of the preparation device and shares the grounding device. Before the yarn passes through the pair of rollers, it can first pass through the bundling ring. The bundling ring not only ensures the bundling effect of the yarn, prevents fiber shedding and entanglement, but also can conduct the static electricity generated by fiber friction. Static electricity can cause the fibers to expand, accelerate braiding damage, and affect the performance of the composite material.

[0029] A preparation device for a three-dimensional braided preform (denoted as device A) as described in any one of the above items, where n > 2;

[0030] For each notch in the six-notch circular plates of the nth layer that is not opposite to other notches, the base of the braided yarn carrier in each notch fills one notch of a two-notch circular plate, and the other notch of this two-notch circular plate is filled by the base of another braided yarn carrier.

[0031] A preparation device for a three-dimensional braided preform (denoted as device B) according to any one of the above, where n = 2;

[0032] In each six-notch circular plate of the nth layer, the number of notches that are not opposite to other notches is 3, which are respectively denoted as notch a, notch b, and notch c, and notch b is located between notch a and notch c;

[0033] The base of the braided yarn carrier in notch a fills one notch of a two-notch circular plate, and the other notch of this two-notch circular plate is filled by the base of another braided yarn carrier. This two-notch circular plate is denoted as dial a;

[0034] The base of the braided yarn carrier in notch b fills one notch of a two-notch circular plate, and the other notch of this two-notch circular plate is filled by the base of another braided yarn carrier. The braided yarn carrier corresponding to the other base of the braided yarn carrier is denoted as braided yarn carrier b, and this two-notch circular plate is denoted as dial b;

[0035] The base of the braided yarn carrier in notch c fills one notch of a two-notch circular plate, and the other notch of this two-notch circular plate is filled by the base of another braided yarn carrier. This two-notch circular plate is denoted as dial c.

[0036] A preparation device for a three-dimensional braided preform (denoted as device C) according to any one of the above, where n = 2;

[0037] In each six-notch circular plate of the nth layer, the number of notches that are not opposite to other notches is 3, which are respectively denoted as notch a, notch b, and notch c, and notch b is located between notch a and notch c;

[0038] The base of the braided yarn carrier in notch a fills one notch of a two-notch circular plate, and the other notch of this two-notch circular plate is filled by the base of another braided yarn carrier. This two-notch circular plate is denoted as dial a;

[0039] The base of the braided yarn carrier in notch b does not fill one notch of a two-notch circular plate;

[0040] The base of the braided yarn carrier in notch c fills one notch of a two-notch circular plate, and the other notch of this two-notch circular plate is filled by the base of another braided yarn carrier. This two-notch circular plate is denoted as dial c.

[0041] The present invention also provides a method for preparing a three-dimensional braided preform. Using a preparation device for a three-dimensional braided preform as described above (i.e., device A or B), the specific process is as follows: After controlling each yarn carrier to carry yarn, all the yarns are bundled and then wound. During the winding process, all the corner wheels are alternately controlled to rotate 60° in the same direction, and all the dials are alternately controlled to rotate 180° in the same direction. The rotation directions of the corner wheels and the dials are opposite. Weaving is carried out at a set weaving angle as required. After repeating many times, a three-dimensional braided preform is obtained. Among them, the reverse rotation of the corner wheels and the dials causes the yarns carried by all the yarn carriers to intersect, overlap, and interlock with each other in the space of the dials, forming the weaving nodes in the three-dimensional braided preform. When the corner wheels and the dials alternate once, a minimum weaving unit cross-section of the three-dimensional braided preform is formed. The weaving nodes in this cross-section are distributed according to the layout positions of the dials, and the inner and outer layer weaving nodes are interlocked as a whole. When the corner wheels and the dials repeatedly alternate, the minimum weaving unit cross-section grows according to a certain rule to form a three-dimensional braided preform of a certain length.

[0042] The present invention also provides a method for preparing a three-dimensional braided preform. Using a preparation device for a three-dimensional braided preform as described above (i.e., device B), the specific process is as follows: After controlling all the yarn carriers except the weaving yarn carrier b to carry yarn, all the yarns are bundled and then wound. During the winding process, all the corner wheels are alternately controlled to rotate 60° in the same direction, and all the dials except the dial b are alternately controlled to rotate 180°. The rotation directions of the dial a and the dial c are opposite (so that the surface texture of the three-dimensional braided preform is more uniform and smooth), and the rotation directions of the other dials except the dials a to c and the corner wheels are opposite. After repeating many times, a three-dimensional braided preform is obtained.

[0043] The present invention also provides a method for preparing a three-dimensional braided preform. Using a preparation device for a three-dimensional braided preform as described above (i.e., device C), the specific process is as follows: After controlling each yarn carrier to carry yarn, all the yarns are bundled and then wound. During the winding process, all the corner wheels are alternately controlled to rotate 60° in the same direction, and all the dials are alternately controlled to rotate 180°. The rotation directions of the dial a and the dial c are opposite (so that the surface texture of the three-dimensional braided preform is more uniform and smooth), and the rotation directions of the other dials except the dials a and c and the corner wheels are opposite. After repeating many times, a three-dimensional braided preform is obtained. The three-dimensional braided preform prepared by this method has a more rounded outer contour, and the angular structure is weakened or even disappears.

[0044] As a preferred technical solution:

[0045] A method for preparing a three-dimensional braided preform as described in any one of the above, wherein the yarn is a carbon fiber yarn, the ambient temperature is 20-25 °C, and the ambient relative humidity is 60-70%. This can improve the weaving fluency of the carbon fiber yarn and reduce the probability of fluffing and filament breakage. The yarn carrier for the weaving yarn filled in the slots of the first to n-1 layer six-slotted circular plates corresponding to the base of the weaving yarn carrier is denoted as the weaving yarn carrier X, and the other weaving yarn carriers are denoted as the weaving yarn carrier Y. The diameter of the yarn carried by the weaving yarn carrier X is greater than the diameter of the yarn carried by the weaving yarn carrier Y. This can improve the stiffness of the internal weaving nodes, help support the overall contour of the three-dimensional braided preform, and at the same time reduce the unevenness of the weaving nodes, making the surface of the three-dimensional braided preform relatively more conformable.

[0046] The present invention also provides a three-dimensional braided preform prepared by using the method for preparing a three-dimensional braided preform as described in any one of the above. It has an n-layer structure, and each layer is numbered starting from 1 from the inside to the outside. The i-th layer is connected to the i-1-th layer by 12×(i - 3)+18 evenly distributed weaving nodes, where 2 ≤ i ≤ n. When the preparation device further includes a carrier for the lining yarn, in the structure of the three-dimensional braided preform, between the i-th layer and the i-1-th layer, the holes between some or all of the weaving nodes are filled.

[0047] Compared with existing fiber structures such as fiber parallel bodies, fiber wound bodies, fiber braided tubes, and fiber felts (as shown in the existing fiber structures Figure 22 ), in the three-dimensional braided preform of the present invention, yarns are regularly distributed in the radial direction, axial direction, and other spatial directions between the two. It belongs to a spatially integrated structure. Each yarn intersects / laps / interlocks with each other in space to form an axially extended integral structure. In the cross-sectional direction, it is an overall coherent solid-like structure without structural delamination, as shown in Figure 15 . Among them, the number, thickness of the inner circle 3 / middle circle 4 / outer circle 5, and the size of the holes between the circles can be controlled by adjusting the weaving process and yarn specifications. These macroscopic layer structures are obtained through a regular combination of a series of yarn weaving nodes. Each weaving node of the three-dimensional braided preform of the present invention can be freely designed in terms of the number and position distribution. Each weaving node forms a spatial binding force on the interlocked multi-strand yarns, effectively suppressing the tendency of the yarn volume to expand and contract, disrupting the microcrack propagation path, and effectively alleviating the tendency of microcracks to rapidly extend and damage along a certain direction. It can make the crack quickly stagnate within a shorter path, as shown in Figure 18 . The different color rods in it represent the yarns of each path. While the yarns extend axially in a buckling manner, they also horizontally penetrate the overall structure of the three-dimensional braided preform. The holding forces from the outside to the inside provided by numerous weaving nodes are evenly distributed on the three-dimensional braided preform. The overall structural integrity of the three-dimensional braided preform is much higher than that of other core-shell delaminated structures or randomly arranged felted fiber structures. The effect of suppressing the structural delamination of the three-dimensional braided preform of the present invention is very significant.

[0048] Compared with existing three-dimensional preforms with laid-up layers, three-dimensional orthogonal woven preforms, and 2.5D preforms, the three-dimensional woven preform of the present invention is a three-dimensional integral structure that is self-enclosed radially and can be infinitely extended axially. Except for yarn breaks in the axial cross-section, there is no additional break cross-section, no auxiliary edge sealing is required, and there are no additional process problems such as the number of layers, laying direction, warp and weft yarns, and Z-direction binding yarns.

[0049] Compared with three-dimensional four-directional woven preforms (three-dimensional weaving by the four-step method), the three-dimensional woven preform of the present invention is different in that: (1) The woven yarns of the three-dimensional four-directional woven preform are arranged in a matrix in rows and columns, and each woven yarn moves alternately along rows and columns under the drive of the yarn carrier (such as Figure 20 and Figure 21As shown in the figure), any braiding node of the three-dimensional braided preform of the present invention can be freely designed to be present or not and to be positioned, and the path of the yarn from the outside to the inside can be freely designed, which has a higher degree of design freedom and realizes the local design of mechanical properties. For example, the dense and sparse distribution of braided nodes can be continuously changed. At this time, the bending resistance, shear resistance, impact resistance and other properties at different positions will be different, and its outer contour can be arbitrarily changed based on this feature; (2) The structure of the three-dimensional four-way braided preform is relatively simple, and is limited by the matrix row and column motion principle of the four-step yarn carrier. The basic motion trajectory is mostly the overall lateral and longitudinal movement of a group of yarn carriers, which seriously limits the flexibility of the structural design within a row and the internal and external structure of the preform. The density distribution of the structure is differentiated, and the outline of the obtained preform is mainly a square solid outline. The four edges and corners of the preform are clear, and the bending degree of the yarn at the edges and corners is large, which is the main stress failure point when the preform is used. The shape outline of the preform is relatively simple; the three-dimensional woven preform structure of the present invention has a high degree of freedom in design, and can be designed to have dense arrangement of the outer ring braiding nodes and sparse arrangement of the inner ring braiding nodes, but there are still yarns evenly running through the two ring structures to make them a whole; (3) The braiding nodes in the three-dimensional four-way braided preform need to be generated or disappeared at the same time in both the horizontal and vertical columns, and any braiding node in the three-dimensional woven preform structure of the present invention can be independently realized to be present or absent, for example For example, in a preform, it is necessary to achieve high tensile strength in one part of the structure and high bending strength in another part at the same time, while the surface structure can still remain consistent. However, the three-dimensional four-way braided preform cannot achieve this function because its internal and external structures cannot be independently designed and formed. The three-dimensional braided preform structure of the present invention only needs to design the same surface braiding trajectory, reduce the number of braiding nodes in the part with high tensile strength, increase the braiding pitch distribution, increase the number of braiding nodes in the part with high bending strength, and reduce the braiding pitch distribution, so as to achieve this; (4) The three-dimensional four-way braided preform does not reserve a position for the axial lining yarn that does not participate in the braiding, and needs to sacrifice part of the yarn carrier in the braiding trajectory to fix it. Axial lining yarns: The thickness of the axial lining yarns will seriously affect the mechanical properties of the overall structure. At the same time, these lining yarns will be skewed and bent due to the movement of the weaving yarns, and the enhancement effect of their axial tensile properties will be affected. The three-dimensional woven preform of the present invention naturally leaves axial lining yarn space in the axial direction. Even if the lining yarns are relatively thick, the impact on the weaving yarn structure will be very limited; (5) The three-dimensional woven preform structure of the present invention has excellent profiling ability of the overall structure because of the independent design characteristics of each weaving node. It can approach the net size molding target contour structure (such as products with different thicknesses and cross-sections, products with large cross-sectional shapes) to the greatest extent, while the profiling ability of the three-dimensional four-way woven preform is very limited.

[0050] Beneficial effects:

[0051] (1) The three-dimensional braided preform of the present invention has the characteristic of circular symmetry in cross section. The braided nodes on the surface of the three-dimensional braided preform are more evenly distributed, coherent and dense, and the surface unevenness is relatively smaller. Therefore, the composite material prepared from the three-dimensional braided preform is subjected to relatively more uniform stress when subjected to external loads, and is not easily damaged and failed quickly due to stress concentration. However, the cross section of the preform in CN114990778B can only show symmetry along the X / Y axis, with obvious angular structures, a small number of braided nodes, and a sparse distribution, resulting in a lack of surface structure. As a result, the mechanical properties of the composite material prepared from the preform are limited.

[0052] (2) The cross-sectional structure of the three-dimensional braided preform of the present invention can be enlarged proportionally and can be gradually enlarged proportionally according to the target requirements. The enlarged preform structure is consistent with the initial structure in layout and has stable and consistent performance; while the cross-sectional structure of the three-dimensional braided preform in CN114990778B Figure 6 and Figure 24 The structure cannot be enlarged proportionally, or the structural shortcomings will also be magnified when it is enlarged.

[0053] (3) The braiding nodes of the three-dimensional braided preform of the present invention can be independently designed to be present or absent, which enriches the design types of the preform structure and can realize the differentiated design of the structure and performance of different parts in a single preform. However, the braiding equipment in CN114990778B only has corner wheels but no dials, and the structure of the resulting preform cannot realize the independent control of the presence or absence of braiding nodes. For example, when the control of a corner wheel stops working, the preform structure will be incomplete and cannot complete continuous braiding and forming.

[0054] (4) The number of braided knots and yarn content of the three-dimensional braided preform of the present invention are significantly greater than those in CN114990778B. Figure 6 and Figure 24 The number of braided nodes and yarn content of the structure, the three-dimensional braided preform of the present invention relies on a large number of braided nodes to be tightly interlocked from the inside out, so that the multi-layer yarn forms a denser overall non-layered structure, and the surface braided nodes of the three-dimensional braided preform are relatively evenly distributed, which reduces the surface structural defects of the three-dimensional braided preform and is conducive to improving the static and dynamic mechanical properties of the composite material. At the same time, the three-dimensional braided preform of the present invention can freely add axial lining yarns at the holes to further improve the mechanical properties of the three-dimensional braided preform, while the three-dimensional braided preform of CN114990778B Figure 6 and Figure 24 The yarn carrier cannot be arranged at the hole in the hole, resulting in the inability to add lining yarn to the hole. Therefore, it is different from the method of CN114990778B. Figure 6 and Figure 24 Compared with the preform shown in the figure, the three-dimensional braided preform of the present invention has improved axial tensile performance due to the axial lining yarn, and the impact resistance is improved because the structure from the inside to the outside is highly integrated and dense. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Schematic diagram of a three-dimensional braided preform of the prior art;

[0056] Figure 2 Schematic diagram of a device according to Embodiment A1 of the present invention;

[0057] Figure 3 Schematic diagram of the braiding - bundling - winding process of the three-dimensional braided preform of the present invention;

[0058] Figure 4 Schematic diagram of braiding using a device according to Embodiment A6; In the figure, 7 corner wheels rotate clockwise simultaneously, all dials rotate in the opposite direction to the corner wheels, and the fibers on all routes intersect, overlap, and interlock with each other in the space of the dials to form braiding knots;

[0059] Figure 5 For Figure 4 Physical diagram of the three-dimensional braided preform prepared by the shown preparation device;

[0060] Figure 6 For Figure 7 Axial view of the three-dimensional braided preform shown;

[0061] Figure 7 Cross-sectional schematic diagram of the three-dimensional braided preform of the present invention without a filled hollow core;

[0062] Figure 8 Cross-sectional schematic diagram of the three-dimensional braided preform of the present invention with only a partially filled hollow core;

[0063] Figure 9 Cross-sectional schematic diagram of the three-dimensional braided preform of the present invention with a completely filled hollow core; Figure 8 , Figure 9 In, the black circles represent the axial lining yarns, and the sizes of the black circles represent the thicknesses of the lining yarns;

[0064] Figure 10 Movement trajectory diagram of the yarn when the preparation device of the three-dimensional braided preform of the present invention is in use;

[0065] Figure 11 Schematic diagram of a corner wheel with a circular slide rail and a circular through-hole in the preparation device of the three-dimensional braided preform of the present invention; In the figure, the black dots represent the positions of the lining yarn carriers;

[0066] Figure 12 Cross-sectional schematic diagram of the base of the lining yarn carrier containing a circular slide rail in the preparation device of the three-dimensional braided preform of the present invention;

[0067] Figure 13 Schematic diagram of a single lining yarn carrier in the preparation device of the three-dimensional braided preform of the present invention; In the figure, the spheres on the thickness surface of the lining yarn carrier represent the balls;

[0068] Figure 14 Schematic diagram of a device for Embodiment A4 of the present invention;

[0069] Figure 15 Cross-sectional schematic diagram of a three-dimensional braided preform when the corner wheels in the device for preparing the three-dimensional braided preform of the present invention are three layers;

[0070] Figure 16 Schematic diagram of the structure of a yarn spindle in the device for preparing the three-dimensional braided preform of the present invention;

[0071] Figure 17 Schematic diagram of the structure of a yarn withdrawal auxiliary frame in the device for preparing the three-dimensional braided preform of the present invention;

[0072] Figure 18 Weaving section of the three-dimensional braided preform of the present invention and its enlarged schematic diagram;

[0073] Figure 19 8-shaped movement trajectory diagram of yarns of a conventional tube sleeve knitting machine in the prior art;

[0074] Figure 20 Schematic diagram of the principle of four-step three-dimensional braiding in the prior art; in the figure, x represents the horizontal direction, x' represents the 45° direction counterclockwise from x, y represents the vertical direction of x, and y' represents the 45° direction counterclockwise from y;

[0075] Figure 21 Schematic diagram of the steps of four-step three-dimensional braiding in the prior art; in the figure, a is the initial state during four-step three-dimensional braiding, b is the schematic diagram at the first step of four-step three-dimensional braiding, c is the schematic diagram at the second step of four-step three-dimensional braiding, d is the schematic diagram at the third step of four-step three-dimensional braiding, and e is the schematic diagram at the fourth step of four-step three-dimensional braiding;

[0076] Figure 22 Schematic diagram of the structure of a conventional fiber structure; in the figure, a is a fiber parallel body, b is a fiber winding body, c is a fiber braided tube body, and d is a fiber felt body;

[0077] Figure 23 Schematic diagram of a device for Embodiment A7 of the present invention;

[0078] Figure 24 Schematic diagram of a device for Embodiment A2 of the present invention;

[0079] Figure 25 Schematic diagram of a device for Embodiment A3 of the present invention;

[0080] Figure 26 Schematic diagram of a device of the present invention's Embodiment A5 with two yarn carriers for lining yarns respectively provided on two corner wheels of only the second and third layers;

[0081] Figure 27 Schematic diagram of a device for Embodiment A6 of the present invention;

[0082] Figure 28 Schematic diagram of a device for Embodiment A5 of the present invention, with 4 lining yarn carriers provided on the corner wheels of the first layer and 1 lining yarn carrier provided on each of the corner wheels of the second and third layers;

[0083] Wherein, 1 - yarn, 2 - knitting node, 3 - inner ring, 4 - middle ring, 5 - outer ring. Specific implementation manners

[0084] The present invention will be further described below in conjunction with specific implementation manners. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0085] Embodiment A1

[0086] A device for preparing a three - dimensional braided preform, comprising a chassis, corner wheels, a dial, and knitting yarn carriers;

[0087] The knitting yarn carrier comprises a knitting yarn carrier base and a knitting yarn carrier straight rod;

[0088] Each knitting yarn carrier has a matching knitting yarn spindle (as shown in Figure 16 ) and a knitting yarn unwinding auxiliary frame (as shown in Figure 17 ). The porcelain eyes on the knitting yarn unwinding auxiliary frame are made of alumina or titanium oxide;

[0089] The number of corner wheels, dials, and knitting yarn carrier bases is multiple. Each corner wheel has a matching corner wheel drive motor, and each dial has a matching dial drive motor;

[0090] The corner wheel is a six - notch circular plate;

[0091] The formation process of the six - notch circular plate is as follows: Select 6 regions a on the circular plate u that have the same shape, the same size, do not overlap with each other, and are evenly distributed around the center circumference of the circular plate u. Region a is enclosed by 2 arcs, and one of the arcs coincides with the edge of the circular plate u. After cutting off the 6 regions a to form 6 cuts, the six - notch circular plate is obtained;

[0092] Each cut of the six - notch circular plate is filled with 1 knitting yarn carrier base;

[0093] The dial is a two - notch circular plate;

[0094] The process of forming a two-cut circular plate is as follows: select two regions b on the circular plate v that are of the same shape and size, do not overlap each other, and are evenly distributed around the central circumference of the circular plate u. The regions b are surrounded by two arcs, one of which coincides with the edge of the circular plate v. After removing the two regions b to form two cuts, a six-cut circular plate is obtained.

[0095] The shape and size of area a, area b and the bottom surface of the base of the braiding yarn carrier are the same;

[0096] All six-slit circular plates are distributed in n layers, where n ≥ 2. Each layer is numbered starting from 1 from the inside out. The number of six-slit circular plates in the first layer is 1, and the number of six-slit circular plates in the i-th layer is 6 × (i-1), where 2 ≤ i ≤ n. Any two adjacent six-slit circular plates are arranged with a spacing of 1. The six-slit circular plates in the i-th layer are evenly distributed, and the lines connecting their centers form a regular hexagon. The vertices of the regular hexagons corresponding to the 2nd to nth layers are distributed on the six lines radiating outward from the center point of the six-slit circular plate in the first layer.

[0097] Each cutout of the six-cut circular plate is filled with a braided yarn carrier base; any two adjacent six-cut circular plates have one cutout facing each other, and the braided yarn carrier bases in the two opposite cutouts are simultaneously filled with two cutouts of a two-cut circular plate;

[0098] A metal bunching ring, a pair of rollers and a winding wheel are arranged above the braiding yarn carrier. The metal bunching ring is located below the pair of rollers and is grounded, and the winding wheel is located above the pair of rollers.

[0099] Example A2

[0100] A preparation device for a three-dimensional braided preform is basically the same as Example A1, except that: at least one corner wheel is provided with a lining yarn carrier located at the center of the corner wheel; the lining yarn carrier includes a lining yarn carrier base and a lining yarn carrier straight rod, each lining yarn carrier has a matching lining yarn spindle and a lining yarn withdrawal auxiliary frame, and the porcelain eye on the lining yarn withdrawal auxiliary frame is made of aluminum oxide or titanium oxide.

[0101] Example A3

[0102] A device for preparing a three-dimensional braided preform is basically the same as that in embodiment A1, except that: at least one corner wheel is provided with a lining yarn carrier greater than one located at the center of the corner wheel;

[0103] like Figure 13 As shown, the lining yarn carrier includes a lining yarn carrier base and a lining yarn carrier straight rod. The lining yarn carrier base is circular in shape, and balls are embedded in the circumference and bottom surfaces.

[0104] Each carrier for the weft yarn of the backing yarn has a supporting bobbin for the backing yarn and an auxiliary frame for unwinding the backing yarn. The porcelain eye on the auxiliary frame for unwinding the backing yarn is made of alumina or titanium oxide.

[0105] As Figure 11 shown, the corner wheel provided with the carrier for the weft yarn of the backing yarn is provided with a circular slide rail and a circular through hole. The circular through hole is located directly above the circular slide rail.

[0106] The center of the circular slide rail is located on the central axis of the corner wheel, and the base of the carrier for the weft yarn of the backing yarn is slidably connected to the circular slide rail.

[0107] The circular through hole is used for the straight rod of the carrier for the weft yarn of the backing yarn to pass through. The diameter of the circular through hole is smaller than the width of the circular slide rail. The schematic cross-section of the base of the carrier for the weft yarn of the backing yarn and the circular slide rail is as Figure 12 shown.

[0108] Example A4

[0109] A device for preparing a three-dimensional braided preform is basically the same as that in Example A1, except that:

[0110] When n > 2, for the incisions in each six-incision circular plate of the nth layer that are not opposite to other incisions, the base of the carrier for the braided yarn in each incision fills one incision of a two-incision circular plate, and the other incision of the two-incision circular plate is filled by the base of another carrier for the braided yarn.

[0111] When n = 2, in each six-incision circular plate of the nth layer, the number of incisions that are not opposite to other incisions is 3, which are respectively denoted as incision a, incision b, and incision c. Incision b is located between incision a and incision c.

[0112] The base of the carrier for the braided yarn in incision a fills one incision of a two-incision circular plate, and the other incision of the two-incision circular plate is filled by the base of another carrier for the braided yarn.

[0113] The base of the carrier for the braided yarn in incision b fills one incision of a two-incision circular plate, and the other incision of the two-incision circular plate is filled by the base of another carrier for the braided yarn.

[0114] The base of the carrier for the braided yarn in incision c fills one incision of a two-incision circular plate, and the other incision of the two-incision circular plate is filled by the base of another carrier for the braided yarn.

[0115] Example A5

[0116] A device for preparing a three-dimensional braided preform is basically the same as that in Example A3, except that: n > 2;

[0117] For the cuts in each six-cut circular plate of the nth layer that are not opposite to other cuts, the base of the knitting yarn carrier in each cut fills one cut of a two-cut circular plate, and the other cut of this two-cut circular plate is filled by the base of another knitting yarn carrier.

[0118] Example A6

[0119] A device for preparing a three-dimensional braided preform is basically the same as that in Example A3, except that: n = 2;

[0120] In each six-cut circular plate of the nth layer, the number of cuts that are not opposite to other cuts is 3, which are respectively denoted as cut a, cut b, and cut c, and cut b is located between cut a and cut c;

[0121] The base of the knitting yarn carrier in cut a fills one cut of a two-cut circular plate, and the other cut of this two-cut circular plate is filled by the base of another knitting yarn carrier. This two-cut circular plate is denoted as turntable a;

[0122] The base of the knitting yarn carrier in cut b fills one cut of a two-cut circular plate, and the other cut of this two-cut circular plate is filled by the base of another knitting yarn carrier. The knitting yarn carrier corresponding to the other base of the knitting yarn carrier is denoted as knitting yarn carrier b, and this two-cut circular plate is denoted as turntable b;

[0123] The base of the knitting yarn carrier in cut c fills one cut of a two-cut circular plate, and the other cut of this two-cut circular plate is filled by the base of another knitting yarn carrier. This two-cut circular plate is denoted as turntable c.

[0124] Example A7

[0125] A device for preparing a three-dimensional braided preform is basically the same as that in Example A6, except that the base of the knitting yarn carrier in cut b does not fill one cut of a two-cut circular plate.

[0126] Example B1

[0127] A method for preparing a three-dimensional braided preform is as follows:

[0128] (1) Preparation of raw materials and the device used for the three-dimensional braided preform;

[0129] Yarn: Carbon fiber yarn, with a tensile strength of 4900 MPa, a breaking elongation of 1.8%, and a fineness specification of 6k;

[0130] Device: A device in Example A1, as Figure 2As shown in the figure, the number of layers of the angle wheels is 2, the number of angle wheels is 7, the number of dials is 12, the number of bases of the knitting yarn carrier is 42, and the porcelain eyes on the knitting yarn take-up auxiliary frame are made of alumina;

[0131] (2) First, unwind the yarn from the standard reel and then wind it onto the knitting yarn spindle. Then, concentrically assemble the knitting yarn spindle and the knitting yarn take-up auxiliary frame onto the straight rod of the matching knitting yarn carrier. Finally, pass the yarn on the knitting yarn spindle through the porcelain eyes on the side of the knitting yarn take-up auxiliary frame and bundle it through the metal bundling ring;

[0132] (3) Weave a three-dimensional woven preform;

[0133] As Figure 3 shown in the figure, after bundling all the yarns, first pass them through a pair of rollers, and then wind them through a continuously rotating take-up wheel. During the winding process, control the rotation of the angle wheels and the dials so that the knitting machine weaves at a knitting angle of 30°. After the winding is completed, a three-dimensional woven preform is obtained. The control process is as follows:

[0134] (a) Control all the angle wheels to rotate counterclockwise by 60° in the same direction under the drive of the angle wheel drive motor;

[0135] (b) Control all the dials to rotate clockwise by 180° in the same direction under the drive of the dial drive motor;

[0136] (c) Repeat steps (a) to (b) multiple times. The movement trajectory of the yarn is as Figure 10 shown in the figure;

[0137] The ambient temperature in steps (2) to (3) is 23°C, and the ambient relative humidity is 68%.

[0138] The finally obtained three-dimensional woven preform has a two-layer structure. Each layer is numbered from 1 from the inside to the outside. The i-th layer is connected to the (i - 1)-th layer by 12×(i - 3) + 18 evenly distributed knitting joints, where i is 2. The axial tensile fracture strength of the three-dimensional woven preform is 2.7 kN, and the fracture elongation rate is 3.6%.

[0139] Example B2

[0140] A method for preparing a three-dimensional woven preform is as follows:

[0141] (1) Prepare the yarn and the device;

[0142] Yarn: Carbon fiber yarn, with a tensile strength of 4900 MPa, a fracture elongation rate of 1.8%, and a thickness specification of 6k;

[0143] Device: A device of Example A2, as Figure 24As shown, the number of layers of the corner wheels is 3, the number of corner wheels is 19, the number of dials is 42, and the number of bases of the braided yarn carrier is 114. One yarn carrier for the backing yarn is provided on each corner wheel. The porcelain eyes on the braided yarn unwinding auxiliary frame are made of alumina, and the porcelain eyes on the backing yarn unwinding auxiliary frame are made of alumina;

[0144] (2) First, wind the yarns around the braided yarn spindles and the backing yarn spindles respectively. Then, concentrically assemble the braided yarn spindles and the braided yarn unwinding auxiliary frame onto the straight rod of the matching braided yarn carrier, and at the same time, concentrically assemble the backing yarn spindles and the backing yarn unwinding auxiliary frame onto the straight rod of the matching backing yarn carrier. Finally, pass the yarns on the braided yarn spindles and the backing yarn spindles through the porcelain eyes on the side of the braided yarn unwinding auxiliary frame and the porcelain eyes on the side of the backing yarn unwinding auxiliary frame respectively, and then bundle them through the metal bundling ring;

[0145] (3) Weave a three-dimensional braided preform;

[0146] After bundling all the yarns, first pass them through a pair of rollers, and then wind them through a continuously rotating winding wheel. During the winding process, control the rotation of the corner wheels and the dials to make the knitting machine knit at a 30° knitting angle. After the winding is completed, a three-dimensional braided preform is obtained. The control process is as follows:

[0147] (a) Control all the corner wheels to rotate counterclockwise by 60° in the same direction under the drive of the corner wheel drive motor;

[0148] (b) Control all the dials to rotate clockwise by 180° in the same direction under the drive of the dial drive motor;

[0149] (c) Repeat steps (a) to (b) multiple times;

[0150] The ambient temperature in steps (2) to (3) is 25°C, and the ambient relative humidity is 70%.

[0151] The finally obtained three-dimensional braided preform has a 3-layer structure. Each layer is numbered from 1 from the inside to the outside. The i-th layer is connected to the (i - 1)-th layer by 12×(i - 3) + 18 evenly distributed knitting nodes. Between the i-th layer and the (i - 1)-th layer, the holes between all the knitting nodes are filled, 2 ≤ i ≤ 3. The axial tensile breaking strength of the three-dimensional braided preform is 16.8 kN, and the breaking elongation rate is 3.8%.

[0152] Example B3

[0153] A method for preparing a three-dimensional braided preform is as follows:

[0154] (1) Prepare yarns and devices;

[0155] Yarn: Carbon fiber yarn, with a tensile strength of 4900 MPa, an elongation at break of 1.8%, and a fineness specification of 6k;

[0156] Device: A device of Example A3, as Figure 25 shown, where the number of layers of the horn wheels is 3, the number of horn wheels is 19, the number of dials is 42, the number of bases of the braided yarn carrier is 114, 4 carrier devices for the backing yarn are respectively arranged on each horn wheel, the porcelain eyes on the braided yarn unwinding auxiliary frame are made of titanium oxide, and the porcelain eyes on the backing yarn unwinding auxiliary frame are made of titanium oxide;

[0157] (2) First, wind the yarns around the braided yarn spindles and the backing yarn spindles respectively, then concentrically assemble the braided yarn spindles and the braided yarn unwinding auxiliary frame onto the straight rods of the matching braided yarn carrier devices, and at the same time, concentrically assemble the backing yarn spindles and the backing yarn unwinding auxiliary frame onto the straight rods of the matching backing yarn carrier devices. Finally, pass the yarns on the braided yarn spindles and the backing yarn spindles through the porcelain eyes on the sides of the braided yarn unwinding auxiliary frame and the backing yarn unwinding auxiliary frame respectively, and then conduct bunching through the metal bunching ring;

[0158] (3) Weave a three-dimensional braided preform;

[0159] After bunching all the yarns, first pass them through a pair of roller wheels, and then wind them through a continuously rotating winding wheel. During the winding process, control the rotation of the horn wheels and the dials to make the knitting machine weave at a knitting angle of 30°. After the winding is completed, a three-dimensional braided preform is obtained. The control process is as follows:

[0160] (a) Control all the horn wheels to rotate counterclockwise by 60° in the same direction under the drive of the horn wheel drive motor;

[0161] (b) Control all the dials to rotate clockwise by 180° in the same direction under the drive of the dial drive motor;

[0162] (c) Repeat steps (a) to (b) multiple times;

[0163] The ambient temperature in steps (2) to (3) is 20 °C, and the ambient relative humidity is 60%.

[0164] The finally obtained three-dimensional braided preform has a three-layer structure, and each layer is numbered starting from 1 from the inside to the outside. The i-th layer and the (i - 1)-th layer are connected by 12×(i - 3) + 18 evenly distributed knitting nodes. Between the i-th layer and the (i - 1)-th layer, the holes between all the knitting nodes are filled, 2 ≤ i ≤ 3; the axial tensile breaking strength of the three-dimensional braided preform is 21.8 kN, and the elongation at break is 3.3%.

[0165] Example B4

[0166] A method for preparing a three-dimensional braided preform is as follows:

[0167] (1) Prepare yarns and equipment;

[0168] Yarns: Carbon fiber yarns with a tensile strength of 4900 MPa, a breaking elongation of 1.8%, and a fineness specification of 6k;

[0169] Equipment: An equipment of Example A4, as Figure 14 shown, wherein the number of layers of the corner wheels is 3, the number of corner wheels is 19, the number of dials is 72, the number of bases of the braided yarn carrier is 144, and the porcelain eyes on the braided yarn unwinding auxiliary frame are made of alumina;

[0170] (2) First, wind the yarns around the braided yarn spindles, then concentrically assemble the braided yarn spindles and the braided yarn unwinding auxiliary frames onto the straight rods of the matching braided yarn carriers, and finally pass the yarns on the braided yarn spindles through the porcelain eyes on the side of the braided yarn unwinding auxiliary frames and bundle them through the metal bundling rings;

[0171] (3) Braiding the three-dimensional braided preform;

[0172] After bundling all the yarns, first pass them through a pair of roller wheels, and then wind them through the continuously rotating winding wheel. During the winding process, control the rotation of the corner wheels and the dials to make the braiding machine braid at a 30° braiding angle. After the winding is completed, the three-dimensional braided preform is obtained. The control process is as follows:

[0173] (a) Control all the corner wheels to rotate counterclockwise by 60° in the same direction under the drive of the corner wheel drive motor;

[0174] (b) Control all the dials to rotate clockwise by 180° in the same direction under the drive of the dial drive motor;

[0175] (c) Repeat steps (a) to (b) multiple times;

[0176] The ambient temperature in steps (2) to (3) is 23°C, and the ambient relative humidity is 68%.

[0177] The finally prepared three-dimensional braided preform (whose cross-section is as Figure 7 shown, and whose axial section is as Figure 6 shown) has a three-layer structure, and each layer is numbered from 1 from the inside to the outside. The i-th layer is connected to the (i - 1)-th layer by 12×(i - 3) + 18 evenly distributed braiding nodes, where 2 ≤ i ≤ 3; the axial tensile breaking strength of the three-dimensional braided preform is 11.6 kN, and the breaking elongation is 4.0%.

[0178] Example B5

[0179] A method for preparing a three-dimensional braided preform is as follows:

[0180] (1) Prepare the yarn and equipment;

[0181] Yarn: Carbon fiber yarn, with a tensile strength of 4900 MPa, an elongation at break of 1.8%, and a fineness specification of 6k;

[0182] Equipment: A kind of equipment of Example A5, as Figure 26 shown, where the number of layers of the horn wheels is 3, the number of horn wheels is 19, the number of dials is 72, the number of bases of the braided yarn carriers is 144, 2 carrier yarn carriers are respectively arranged on 2 horn wheels of the second layer and 2 horn wheels of the third layer, the porcelain eyes on the braided yarn unwinding auxiliary frame are made of titanium oxide, and the porcelain eyes on the carrier yarn unwinding auxiliary frame are made of titanium oxide;

[0183] (2) First, wind the yarns onto the braided yarn spindles and the carrier yarn spindles respectively, then concentrically assemble the braided yarn spindles and the braided yarn unwinding auxiliary frame onto the straight rods of the matching braided yarn carriers, and at the same time, concentrically assemble the carrier yarn spindles and the carrier yarn unwinding auxiliary frame onto the straight rods of the matching carrier yarn carriers. Finally, pass the yarns on the braided yarn spindles and the carrier yarn spindles through the porcelain eyes on the side of the braided yarn unwinding auxiliary frame and the porcelain eyes on the side of the carrier yarn unwinding auxiliary frame respectively, and then bundle them through the metal bundling ring;

[0184] (3) Weave the three-dimensional braided preform;

[0185] After bundling all the yarns, first pass them through a pair of rollers, and then wind them through the continuously rotating winding wheel. During the winding process, control the rotation of the horn wheels and the dials so that the knitting machine weaves at a knitting angle of 30°. After the winding is completed, the three-dimensional braided preform is obtained. The control process is as follows:

[0186] (a) Control all the horn wheels to rotate counterclockwise by 60° in the same direction under the drive of the horn wheel drive motor;

[0187] (b) Control all the dials to rotate clockwise by 180° in the same direction under the drive of the dial drive motor;

[0188] (c) Repeat steps (a) to (b) multiple times;

[0189] The ambient temperature in steps (2) to (3) is 23 °C, and the ambient relative humidity is 68%.

[0190] The finally obtained three-dimensional braided preform (its cross-section is as Figure 8As shown in the figure, it has a three-layer structure. Each layer is numbered starting from 1 from the inside to the outside. The $i$-th layer is connected to the $(i - 1)$-th layer by $12\times(i - 3)+18$ evenly distributed braiding knots. Between the $i$-th layer and the $(i - 1)$-th layer, the holes between some of the braiding knots are filled, where $2\leq i\leq3$. The axial tensile breaking strength of the three-dimensional braided preform is 13.1 kN, and the breaking elongation rate is 3.9%.

[0191] Example B6

[0192] A method for preparing a three-dimensional braided preform is as follows:

[0193] (1) Prepare the yarns and the device;

[0194] Yarns: Carbon fiber yarns with a tensile strength of 4900 MPa, a breaking elongation rate of 1.8%, and a fineness specification of 6k;

[0195] Device: A device of Example A6, as Figure 27 shown in the figure. Among them, the number of layers of the corner wheels is 2, the number of corner wheels is 7, the number of dials is 30, the number of bases of the braiding yarn carrier is 60. One carrier for the backing yarn is provided on each corner wheel. The porcelain eyes on the braiding yarn unwinding auxiliary frame are made of titanium oxide, and the porcelain eyes on the backing yarn unwinding auxiliary frame are made of titanium oxide;

[0196] (2) First, control the braiding yarn spindles and the backing yarn spindles of all the braiding yarn carriers except the braiding yarn carrier b to wind yarns. Then, concentrically assemble the braiding yarn spindles wound with yarns and the braiding yarn unwinding auxiliary frame onto the straight rods of the matching braiding yarn carriers. At the same time, concentrically assemble the backing yarn spindles and the backing yarn unwinding auxiliary frame onto the straight rods of the matching backing yarn carriers. Finally, pass the yarns on the braiding yarn spindles and the yarns on the backing yarn spindles through the porcelain eyes on the sides of the braiding yarn unwinding auxiliary frame and the backing yarn unwinding auxiliary frame respectively, and then bundle them through the metal bundling ring;

[0197] (3) Braiding the three-dimensional braided preform;

[0198] After bundling all the yarns, first pass them through a pair of roller wheels, and then wind them through the continuously rotating winding wheel. During the winding process, control the rotation of the corner wheels and the dials to make the knitting machine knit at a 30° knitting angle. After the winding is completed, the three-dimensional braided preform is obtained. The control process is as follows:

[0199] (a) Control all the corner wheels to rotate counterclockwise by 60° in the same direction under the drive of the corner wheel drive motor;

[0200] (b) Control the dials except dials b and c to rotate clockwise by 180° in the same direction under the drive of the dial drive motor, and control dial c to rotate counterclockwise by 180° under the drive of the dial drive motor;

[0201] (c) Repeat steps (a) to (b) multiple times;

[0202] The ambient temperature in steps (2) to (3) is 23 °C, and the ambient relative humidity is 68%.

[0203] The finally obtained three-dimensional braided preform has a two-layer structure. Each layer is numbered starting from 1 from the inside to the outside. The i-th layer and the (i - 1)-th layer are connected by 12×(i - 3) + 18 uniformly distributed braiding knots. Between the i-th layer and the (i - 1)-th layer, the holes between all the braiding knots are filled, and i is 2; the axial tensile breaking strength of the three-dimensional braided preform is 3.6 kN, and the breaking elongation rate is 3.2%.

[0204] Example B7

[0205] A method for preparing a three-dimensional braided preform is as follows:

[0206] (1) Prepare yarns and devices;

[0207] Yarns: Carbon fiber yarns, with a tensile strength of 4900 MPa, a breaking elongation rate of 1.8%, and a fineness specification of 6k;

[0208] Devices: A device of Example A7, as Figure 23 shown, where the number of layers of the corner wheels is 2, the number of corner wheels is 7, the number of dials is 24, the number of bases of the braiding yarn carriers is 54, 3 carrier yarn carriers are provided on each corner wheel, the porcelain eyes on the braiding yarn unwinding auxiliary frame are made of titanium oxide, and the porcelain eyes on the carrier yarn unwinding auxiliary frame are made of titanium oxide;

[0209] (2) First, control the braiding yarn spindles and carrier yarn spindles of all braiding yarn carriers except for the braiding yarn carrier b to wind yarns. Then, concentrically assemble the braiding yarn spindles with wound yarns and the braiding yarn unwinding auxiliary frame onto the straight rods of the corresponding braiding yarn carriers. At the same time, concentrically assemble the carrier yarn spindles and the carrier yarn unwinding auxiliary frame onto the straight rods of the corresponding carrier yarn carriers. Finally, pass the yarns on the braiding yarn spindles and the yarns on the carrier yarn spindles through the porcelain eyes on the side of the braiding yarn unwinding auxiliary frame and the porcelain eyes on the side of the carrier yarn unwinding auxiliary frame respectively, and then bundle them through the metal bundling ring;

[0210] (3) Braiding the three-dimensional braided preform;

[0211] After bundling all the yarns, first pass them through a pair of roller wheels, and then wind them through a continuously rotating winding wheel. During the winding process, control the rotation of the corner wheels and the dials to make the knitting machine knit at a 30° knitting angle. After the winding is completed, the three-dimensional braided preform is obtained. The control process is as follows:

[0212] (a)Control all corner wheels to rotate counterclockwise by 60° in the same direction under the drive of the corner wheel drive motor;

[0213] (b)Control the dials except dial c to rotate clockwise by 180° in the same direction under the drive of the dial drive motor, and control dial c to rotate counterclockwise by 180° under the drive of the dial drive motor;

[0214] (c)Repeat steps (a) to (b) multiple times;

[0215] The ambient temperature in steps (2) to (3) is 23°C, and the ambient relative humidity is 68%.

[0216] The finally prepared three-dimensional braided preform has a two-layer structure. Each layer is numbered starting from 1 from the inside to the outside. The i-th layer is connected to the (i - 1)-th layer by 12×(i - 3) + 18 evenly distributed braiding knots. Between the i-th layer and the (i - 1)-th layer, the holes between all the braiding knots are filled, where i is 2; the axial tensile breaking strength of the three-dimensional braided preform is 4.7 kN, and the breaking elongation rate is 3.3%.

[0217] Example B8

[0218] A method for preparing a three-dimensional braided preform is as follows:

[0219] (1)Prepare yarns and devices;

[0220] Yarns: Carbon fiber yarns with a tensile strength of 4900 MPa, a breaking elongation rate of 1.8%, and a thickness specification of 12k;

[0221] Devices: A device as in Example A4, as Figure 4 shown, where the number of corner wheels is 7, the number of dials is 30, the number of bases of the braided yarn carrier is 60, the number of layers of the corner wheels is 2, and the porcelain eyes on the braided yarn unwinding auxiliary frame are made of titanium oxide;

[0222] (2)First, unwind the yarn from the standard reel and then wind it onto the braided yarn spindle. Then, concentrically assemble the braided yarn spindle and the braided yarn unwinding auxiliary frame onto the straight rod of the matching braided yarn carrier. Finally, pass the yarn on the braided yarn spindle through the porcelain eyes on the side of the braided yarn unwinding auxiliary frame and then bundle it through the metal bundling ring;

[0223] (3)Braide the three-dimensional braided preform;

[0224] After bundling all the yarns, first pass them through a pair of rollers, and then wind them through the continuously rotating take-up wheel. During the winding process, control the rotation of the corner wheels and dials to make the braiding machine braid at a 30° braiding angle. After the winding is completed, the three-dimensional braided preform is obtained. The control process is as follows:

[0225] (a) Control all corner wheels to rotate counterclockwise by 60° in the same direction under the drive of the corner wheel drive motor;

[0226] (b) Control all dials to rotate clockwise by 180° in the same direction under the drive of the dial drive motor;

[0227] (c) Repeat steps (a) to (b) multiple times;

[0228] The ambient temperature in steps (2) to (3) is 23°C, and the ambient relative humidity is 68%.

[0229] The finally prepared three-dimensional braided preform (as Figure 5 shown) has a two-layer structure. Each layer is numbered starting from 1 from the inside to the outside. The i-th layer is connected to the (i - 1)-th layer by 12×(i - 3) + 18 evenly distributed braiding nodes. Between the i-th layer and the (i - 1)-th layer, the holes between all braiding nodes are unfilled, and i is 2; the axial tensile breaking strength of the three-dimensional braided preform is 3.0 kN, and the breaking elongation rate is 3.4%.

[0230] Example B9

[0231] A method for preparing a three-dimensional braided preform, the steps are as follows:

[0232] (1) Prepare yarns and devices;

[0233] Yarns: Carbon fiber yarns, with a tensile strength of 4900 MPa, a breaking elongation rate of 1.8%, and a thickness specification of 12k;

[0234] Devices: A device of Example A5, as Figure 28 shown, where the number of corner wheels is 19, the number of dials is 72, the number of bases of the braiding yarn carrier is 144, the number of layers of the corner wheels is 3, 4 yarn carriers for the lining yarns are arranged on 1 corner wheel of the first layer, 1 yarn carrier for the lining yarns is arranged on each of the 6 corner wheels of the second layer and the 12 corner wheels of the third layer, the porcelain eyes on the braiding yarn unwinding auxiliary frame are made of alumina, and the porcelain eyes on the lining yarn unwinding auxiliary frame are made of alumina;

[0235] (2) First, wind the yarns around the braiding yarn spindles and the lining yarn spindles respectively, then concentrically assemble the braiding yarn spindles and the braiding yarn unwinding auxiliary frame onto the straight rods of the supporting braiding yarn carriers, and at the same time concentrically assemble the lining yarn spindles and the lining yarn unwinding auxiliary frame onto the straight rods of the supporting lining yarn carriers. Finally, pass the yarns on the braiding yarn spindles and the yarns on the lining yarn spindles through the porcelain eyes on the side of the braiding yarn unwinding auxiliary frame and the porcelain eyes on the side of the lining yarn unwinding auxiliary frame respectively, and then bundle them through the metal bundling ring;

[0236] (3) Braiding a three-dimensional braided preform;

[0237] After bunching all the yarns, they first pass through a pair of rollers and then are wound by a continuously rotating winding wheel. During the winding process, the angle wheels and the dial are controlled to rotate so that the knitting machine knits at a knitting angle of 30°. After the winding is completed, a three-dimensional knitted preform is obtained. The control process is as follows:

[0238] (a) Control all the angle wheels to rotate counterclockwise in the same direction by 60° under the drive of the angle wheel drive motor;

[0239] (b) Control all the dials to rotate clockwise in the same direction by 180° under the drive of the dial drive motor;

[0240] (c) Repeat steps (a) to (b) multiple times;

[0241] The environmental temperature in steps (2) to (3) is 23 °C, and the environmental relative humidity is 68%.

[0242] The finally obtained three-dimensional knitted preform (whose cross-section is as Figure 9 shown) has a three-layer structure. Each layer is numbered from 1 from the inside to the outside. The i-th layer is connected to the (i - 1)-th layer by 12×(i - 3) + 18 evenly distributed knitting nodes. Between the i-th layer and the (i - 1)-th layer, the holes between all the knitting nodes are filled, 2 ≤ i ≤ 3; the axial tensile breaking strength of the three-dimensional knitted preform is 18.1 kN, and the breaking elongation rate is 3.4%.

[0243] Example B10

[0244] A method for preparing a three-dimensional knitted preform is basically the same as that in Example B9, except that: the control process in step (3) when knitting the three-dimensional knitted preform is: (a) Control all the angle wheels to rotate counterclockwise in the same direction by 60° under the drive of the angle wheel drive motor; (b) Control the dial intervals between the angle wheels of the i-th layer to remain unchanged, and the dial intervals between the angle wheels of the (i - 1)-th layer and the i-th layer to remain unchanged, and the other dials to rotate clockwise in the same direction by 180° under the drive of the dial drive motor; (c) Repeat steps (a) to (b) multiple times.

[0245] The finally obtained three-dimensional knitted preform has a three-layer structure. Each layer is numbered from 1 from the inside to the outside. The i-th layer is connected to the (i - 1)-th layer by 12×(i - 3) + 18 evenly distributed knitting nodes. Between the i-th layer and the (i - 1)-th layer, the holes between all the knitting nodes are filled, 2 ≤ i ≤ 3; the axial tensile breaking strength of the three-dimensional knitted preform is 18.6 kN, and the breaking elongation rate is 3.2%.

Claims

1. A method for preparing a three-dimensional braided preform, characterized in that: The preparation device of the three-dimensional braided preform adopts comprises a chassis, an angle wheel, a dial and a braiding yarn carrier, the braiding yarn carrier comprises a braiding yarn carrier base and a braiding yarn carrier straight rod, the number of the angle wheel, the dial and the braiding yarn carrier base are all multiple, and the characteristic is that the angle wheel is a six-cut circular plate and the dial is a two-cut circular plate; The six-notch circular plate is formed as follows: six regions a of identical shape and size are selected on the circular plate u, which are evenly distributed around the central circumference of the circular plate u and do not overlap with each other. The regions a are surrounded by two arcs, one of which coincides with the edge of the circular plate u. The six regions a are removed to form six notches, resulting in a six-notch circular plate. The process of forming a two-cut circular plate is as follows: select two regions b on the circular plate v that are of the same shape and size, do not overlap each other, and are evenly distributed around the central circumference of the circular plate u. The regions b are surrounded by two arcs, one of which coincides with the edge of the circular plate v. After removing the two regions b to form two cuts, a six-cut circular plate is obtained. The shape and size of area a, area b and the bottom surface of the base of the braiding yarn carrier are the same; All six-slit circular plates are distributed in n layers, where n ≥ 2. Each layer is numbered starting from 1 from the inside out. The number of six-slit circular plates in the first layer is 1, and the number of six-slit circular plates in the i-th layer is 6 × (i-1), where 2 ≤ i ≤ n. Any two adjacent six-slit circular plates are arranged with a spacing of 1. The six-slit circular plates in the i-th layer are evenly distributed, and the lines connecting their centers form a regular hexagon. The vertices of the regular hexagons corresponding to the 2nd to nth layers are distributed on the six lines radiating outward from the center point of the six-slit circular plates in the first layer. Each cutout of the six-cut circular plate is filled with a braided yarn carrier base; any two adjacent six-cut circular plates have one cutout facing each other, and the braided yarn carrier bases in the two opposite cutouts are simultaneously filled with two cutouts of a two-cut circular plate; At least one corner wheel is provided with a lining yarn carrier; The corner wheel is provided with a lining yarn carrier, the number of the lining yarn carrier is 1, and the lining yarn carrier is located at the center of the corner wheel; Alternatively, the angle wheel provided with the lining yarn carriers has a number greater than one lining yarn carrier, and the lining yarn carriers are distributed in a circle around the central axis of the angle wheel; the angle wheel provided with the lining yarn carriers is further provided with a circular slide rail, the center of the circular slide rail is located on the central axis of the angle wheel, and the lining yarn carrier is slidably connected to the circular slide rail; n>2; for each cutout in the six-cutout circular plate of the nth layer that is not opposite to other cutouts, the knitting yarn carrier base in each cutout is filled with one cutout of a two-cutout circular plate, and the other cutout of the two-cutout circular plate is filled with another knitting yarn carrier base; Alternatively, n=2; in each six-cut circular plate of the nth layer, the number of cuts that are not opposite to other cuts is 3, which are respectively recorded as cut a, cut b and cut c, and cut b is located between cut a and cut c; the braiding yarn carrier base in cut a is filled with one cut of a two-cut circular plate, and the other cut of the two-cut circular plate is filled with another braiding yarn carrier base, and the two-cut circular plate is recorded as dial a; the braiding yarn carrier base in cut b is filled with one cut of a two-cut circular plate, and the other cut of the two-cut circular plate is filled with another braiding yarn carrier base. One cutout of a two-cut circular plate, the other cutout of the two-cut circular plate is filled by another braiding yarn carrier base, the braiding yarn carrier corresponding to the other braiding yarn carrier base is marked as braiding yarn carrier b, and the two-cut circular plate is marked as dial b; the braiding yarn carrier base in cutout c fills one cutout of a two-cut circular plate, the other cutout of the two-cut circular plate is filled by another braiding yarn carrier base, and the two-cut circular plate is marked as dial c; The specific process is: after controlling each yarn carrier to carry yarn, all the yarns are bundled and then reeled up. During the reeling process, all the angle wheels are alternately controlled to rotate 60° in the same direction at the same time, and all the dials are alternately controlled to rotate 180° in the same direction at the same time. The rotation directions of the angle wheels and dials are controlled to be opposite. After multiple cycles, a three-dimensional woven preform is obtained.

2. A method for preparing a three-dimensional braided preform, characterized in that: The preparation device of the three-dimensional braided preform adopts comprises a chassis, an angle wheel, a dial and a braiding yarn carrier, the braiding yarn carrier comprises a braiding yarn carrier base and a braiding yarn carrier straight rod, the number of the angle wheel, the dial and the braiding yarn carrier base are all multiple, and the characteristic is that the angle wheel is a six-cut circular plate and the dial is a two-cut circular plate; The six-notch circular plate is formed as follows: six regions a of identical shape and size are selected on the circular plate u, which are evenly distributed around the central circumference of the circular plate u and do not overlap with each other. The regions a are surrounded by two arcs, one of which coincides with the edge of the circular plate u. The six regions a are removed to form six notches, resulting in a six-notch circular plate. The process of forming a two-cut circular plate is as follows: select two regions b on the circular plate v that are of the same shape and size, do not overlap each other, and are evenly distributed around the central circumference of the circular plate u. The regions b are surrounded by two arcs, one of which coincides with the edge of the circular plate v. After removing the two regions b to form two cuts, a six-cut circular plate is obtained. The shape and size of area a, area b and the bottom surface of the base of the braiding yarn carrier are the same; All six-slit circular plates are distributed in n layers, where n ≥ 2. Each layer is numbered starting from 1 from the inside out. The number of six-slit circular plates in the first layer is 1, and the number of six-slit circular plates in the i-th layer is 6 × (i-1), where 2 ≤ i ≤ n. Any two adjacent six-slit circular plates are arranged with a spacing of 1. The six-slit circular plates in the i-th layer are evenly distributed, and the lines connecting their centers form a regular hexagon. The vertices of the regular hexagons corresponding to the 2nd to nth layers are distributed on the six lines radiating outward from the center point of the six-slit circular plates in the first layer. Each cutout of the six-cut circular plate is filled with a braided yarn carrier base; any two adjacent six-cut circular plates have one cutout facing each other, and the braided yarn carrier bases in the two opposite cutouts are simultaneously filled with two cutouts of a two-cut circular plate; At least one corner wheel is provided with a lining yarn carrier; The corner wheel is provided with a lining yarn carrier, the number of the lining yarn carrier is 1, and the lining yarn carrier is located at the center of the corner wheel; Alternatively, the angle wheel provided with the lining yarn carriers has a number greater than one lining yarn carrier, and the lining yarn carriers are distributed in a circle around the central axis of the angle wheel; the angle wheel provided with the lining yarn carriers is further provided with a circular slide rail, the center of the circular slide rail is located on the central axis of the angle wheel, and the lining yarn carrier is slidably connected to the circular slide rail; n=2; in each six-cut circular plate of the nth layer, the number of cuts that are not opposite to other cuts is 3, which are respectively recorded as cut a, cut b and cut c, and cut b is located between cut a and cut c; the braiding yarn carrier base in cut a is filled with one cut of a two-cut circular plate, and the other cut of the two-cut circular plate is filled with another braiding yarn carrier base, and the two-cut circular plate is recorded as dial a; the braiding yarn carrier base in cut b is filled with one One cut of the two-cut circular plate, the other cut of the two-cut circular plate is filled by another braiding yarn carrier base, the braiding yarn carrier corresponding to the other braiding yarn carrier base is recorded as braiding yarn carrier b, and the two-cut circular plate is recorded as dial b; the braiding yarn carrier base in the cut c is filled with one cut of a two-cut circular plate, the other cut of the two-cut circular plate is filled by another braiding yarn carrier base, and the two-cut circular plate is recorded as dial c; The specific process is: after controlling all yarn carriers except the braiding yarn carrier b to carry yarn, all the yarns are bundled and then reeled up. During the reeling process, all the angle wheels are alternately controlled to rotate 60° in the same direction at the same time, all the dials except the dial b are rotated 180° at the same time, the rotation directions of the dial a and the dial c are controlled to be opposite, and the rotation directions of the other dials and angle wheels except the dials a to c are controlled to be opposite. After multiple cycles, a three-dimensional braided preform is obtained.

3. A method for preparing a three-dimensional braided preform, characterized in that: The preparation device of the three-dimensional braided preform adopts comprises a chassis, an angle wheel, a dial and a braiding yarn carrier, the braiding yarn carrier comprises a braiding yarn carrier base and a braiding yarn carrier straight rod, the number of the angle wheel, the dial and the braiding yarn carrier base are all multiple, and the characteristic is that the angle wheel is a six-cut circular plate and the dial is a two-cut circular plate; The six-notch circular plate is formed as follows: six regions a of identical shape and size are selected on the circular plate u, which are evenly distributed around the central circumference of the circular plate u and do not overlap with each other. The regions a are surrounded by two arcs, one of which coincides with the edge of the circular plate u. The six regions a are removed to form six notches, resulting in a six-notch circular plate. The process of forming a two-cut circular plate is as follows: select two regions b on the circular plate v that are of the same shape and size, do not overlap each other, and are evenly distributed around the central circumference of the circular plate u. The regions b are surrounded by two arcs, one of which coincides with the edge of the circular plate v. After removing the two regions b to form two cuts, a six-cut circular plate is obtained. The shape and size of area a, area b and the bottom surface of the base of the braiding yarn carrier are the same; All six-slit circular plates are distributed in n layers, where n ≥ 2. Each layer is numbered starting from 1 from the inside out. The number of six-slit circular plates in the first layer is 1, and the number of six-slit circular plates in the i-th layer is 6 × (i-1), where 2 ≤ i ≤ n. Any two adjacent six-slit circular plates are arranged with a spacing of 1. The six-slit circular plates in the i-th layer are evenly distributed, and the lines connecting their centers form a regular hexagon. The vertices of the regular hexagons corresponding to the 2nd to nth layers are distributed on the six lines radiating outward from the center point of the six-slit circular plates in the first layer. Each cutout of the six-cut circular plate is filled with a braided yarn carrier base; any two adjacent six-cut circular plates have one cutout facing each other, and the braided yarn carrier bases in the two opposite cutouts are simultaneously filled with two cutouts of a two-cut circular plate; At least one corner wheel is provided with a lining yarn carrier; The corner wheel is provided with a lining yarn carrier, the number of the lining yarn carrier is 1, and the lining yarn carrier is located at the center of the corner wheel; Alternatively, the angle wheel provided with the lining yarn carriers has a number greater than one lining yarn carrier, and the lining yarn carriers are distributed in a circle around the central axis of the angle wheel; the angle wheel provided with the lining yarn carriers is further provided with a circular slide rail, the center of the circular slide rail is located on the central axis of the angle wheel, and the lining yarn carrier is slidably connected to the circular slide rail; n=2; in each six-notch circular plate of the nth layer, the number of notches that are not opposite to other notches is 3, which are respectively recorded as notch a, notch b and notch c, and notch b is located between notch a and notch c; the knitting yarn carrier base in notch a is filled with one notch of a two-notch circular plate, and the other notch of the two-notch circular plate is filled with another knitting yarn carrier base, and the two-notch circular plate is recorded as dial a; the knitting yarn carrier base in notch b is not filled with one notch of a two-notch circular plate; the knitting yarn carrier base in notch c is filled with one notch of a two-notch circular plate, and the other notch of the two-notch circular plate is filled with another knitting yarn carrier base, and the two-notch circular plate is recorded as dial c; The specific process is: after controlling each yarn carrier to carry yarn, all the yarns are bundled and then reeled up. During the reeling process, all the angle wheels are alternately controlled to rotate 60° in the same direction at the same time, and all the dials are rotated 180° at the same time. The rotation directions of dial a and dial c are controlled to be opposite, and the rotation directions of other dials and angle wheels except dial a and dial c are controlled to be opposite. After multiple cycles, a three-dimensional woven preform is obtained.

4. The method for preparing a three-dimensional braided preform according to any one of claims 1 to 3, characterized in that: The yarn is carbon fiber yarn, the ambient temperature is 20-25°C, and the relative humidity is 60-70%. The braided yarn carriers corresponding to the braided yarn carrier bases that fill the cutouts of the six-cut circular plates in the 1st to n-1st layers are recorded as braided yarn carriers X, and the other braided yarn carriers are recorded as braided yarn carriers Y. The diameter of the yarn carried by the braided yarn carrier X is greater than the diameter of the yarn carried by the braided yarn carrier Y.

5. A three-dimensional braided preform, characterized in that: The three-dimensional braided preform is prepared by the preparation method of any one of claims 1 to 4, having an n-layer structure, each layer is numbered from 1 from the inside to the outside, the i-th layer and the i-1-th layer are connected by 12×(i-3)+18 evenly distributed braiding nodes, and 2≤i≤n.

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