Method for weaving eccentric rotary body with gradually changing thickness and application thereof

Abstract

The application belongs to the technical field of three-dimensional weaving, and discloses a weaving method and application of an eccentric rotary body thickness gradient fabric, and the steps of the weaving method are as follows: 1. The target fabric is divided into regions; 2. Parameter design: according to the required volume fraction, warp density and weft density, the weaving parameters of each region are calculated, including the weft yarn ply number, the weft yarn layer number, the warp yarn ply number, the warp yarn layer number and the warp yarn column number; 3. Firstly, the weft yarn ply number is determined, then the total warp yarn root number is adjusted, then according to the warp density, the total warp yarn root number and column number of each region are obtained, then the single column total root number is obtained, then according to the designed warp yarn layer number, the warp yarn ply number is obtained; finally, overall adaptability adjustment is carried out; 4. Layer connection weaving technology is adopted for weaving. The method can realize the weaving of the axial continuous thickness change and the weaving of the same section thickness change; and can be suitable for the manufacturing of different specifications of large-size variable-thickness rotary body preforms.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of three-dimensional braided preforms, in particular to a braiding method of eccentric rotating body thickness gradient fabric and application. BACKGROUND

[0002] High-performance fiber reinforced composites are increasingly valued in the fields of aerospace and national defense. Rotating body preforms are commonly used as reinforcing bodies for high-performance fiber reinforced composites. Rotating body preforms are usually prepared by three-dimensional integral braiding (such as the method disclosed in CN106400295A) and circular three-dimensional weaving (such as the method disclosed in CN101811365A). However, these methods are limited by the braiding method and are only suitable for the preparation of small-sized preforms, usually with a diameter limit of less than 500 mm. In addition, a large number of yarns need to be arranged during manufacturing, the weaving machine occupies a large area, the number of workers is large, the process is complicated, and the manufacturing efficiency is low. For large-sized variable-thickness rotating body preforms required for large-sized parts such as aircraft engine casings (with an inner diameter of up to 2 meters), the number of yarns required for one-time forming is larger, and the above-mentioned methods cannot be used to achieve this.

[0003] For the braiding method of high-thickness rotating body, patent CN112877862A "Preparation method of rotating body preform and preparation method of rotating body" and patent CN108004650B "Large-sized variable-thickness rotating body preform and preparation method thereof" are both for rotating bodies with varying thicknesses, but they are both for rotating bodies with the same thickness in the same cross-section. The braiding method for rotating bodies with varying thickness in the same cross-section is not mentioned, and the methods for achieving high-thickness rotating bodies in the two technologies are to stack multiple layers of woven two-dimensional fabric on a rotating body core mold to form a high-thickness rotating body. The adjacent layers of fabric are only stacked together, and there is no fiber connection in the thickness direction, so the interlayer performance is weak and prone to delamination, which is suitable for structural parts with low interlayer performance requirements.

[0004] Therefore, the present application is produced after the inventors' in-depth research. SUMMARY

[0005] The present application aims to overcome the above limitations and provide a braiding method of eccentric rotating body thickness gradient fabric suitable for large-sized and / or multi-dimensional variable-thickness rotating bodies.

[0006] To achieve the above-mentioned purpose, the technical solution of the present application is as follows:

[0007] A braiding method of eccentric rotating body thickness gradient fabric, comprising the following steps:

[0008] S1: dividing the target fabric into regions

[0009] Divide the main body of the target fabric cylinder into different regions according to different positions;

[0010] S2: Calculate the knitting parameters of each region

[0011] According to the required volume fraction, warp density and weft density, the knitting parameters of each region are calculated, including weft yarn ply number, weft yarn layer number, warp yarn ply number, warp yarn layer number and warp yarn column number;

[0012] In step S2, the required parameters are calculated according to the formula S1 is the inner arc length, s2 is the outer arc length, S is the area, j is the warp density, k is the weft density, o is the layer number, z is the total number of warp yarns, n is the weft yarn ply number, δ is the warp yarn shrinkage, Vf is the volume fraction, t is the fiber linear density, and ρ is the fiber bulk density;

[0013] S3: Adjust the knitting parameters of each region

[0014] First, the weft yarn ply number is determined, then the total number of warp yarns is adjusted, then the total number of warp yarns and the number of columns in each region are obtained according to the warp density, then the total number of single columns is obtained, and then the warp yarn ply number is obtained according to the designed number of warp yarn layers;

[0015] Finally, overall adaptive adjustment is performed: adjust the warp yarn ply number to make the circumferential thickness change uniform and smooth, adjust the number of warp yarn columns to match the warp density, and adjust the number of warp yarn layers and plies to make the axial thickness change uniform and smooth;

[0016] S4: Knitting operation

[0017] First, fix the core mold, then use a layer-to-layer knitting machine to perform layer-to-layer knitting operation on each region, and sequentially pass through the processes of cloth laying, material cutting, yarn hanging, carding and knitting. During the knitting process, at least one of the following thickness change treatments is performed in different regions according to the calculated parameters: adding or reducing the number of yarn columns, adding or reducing the number of yarn plies, and adding or reducing the number of layers. Finally, the fabric is obtained, and the layers of warp yarns and the layers of weft yarns are layer-to-layer knitted together.

[0018] Further, in step S3, first, according to the calculated number of layers of warp yarns in each region, the single column ply number of warp yarns in each layer, and the number of columns of warp yarns, the number of weft yarn layers in the thin area is taken as a unified standard, the number of weft yarn layers in the thick area is reduced to maintain the consistency of the number of weft yarns, and then the number of layers of warp yarns and the single column ply number of warp yarns in each layer are adjusted according to the set volume fraction to meet the set volume fraction.

[0019] Further, in step S1, the fabric is divided into different regions according to the height, and each M mm is divided into different regions according to the change trend of the circumferential cross-sectional area in the height direction, and M is 5-10 mm;

[0020] In step S2, when calculating the parameters of each region, the number of weft yarn layers in the thin region is used as the benchmark. Based on this, the difference between the number of weft yarn layers in the thick region and the number of weft yarn layers in the thin region shall not exceed three layers, and the total number of plies of warp and weft yarns shall not exceed seven.

[0021] Furthermore, in the warp reduction design, the reduction position is set within three layers of the inner and outer surfaces of the fabric. The reduction position is the same for the same layer of the continuous knitting machine, and the same number of layers is maintained when reducing layers at the same height.

[0022] Furthermore, in the weaving process of step S4, yarn reduction is an operation performed when the fabric height reaches a certain position during the weaving process, involving reducing layers or strands. Due to the height difference between the inside and outside of the fabric, the number of layers reduced near the inner surface is determined by the internal height, and the number of layers reduced on the outer surface is determined by the external height.

[0023] When reducing the inner layer, all the outer layer yarns corresponding to the number of layers to be reduced should be moved inward by one layer; when reducing the outer layer, the inner layer portion corresponding to the number of layers to be reduced should be moved outward by one layer as a whole, and the weft yarn should be wound using different weft yarn winding methods for different warp yarn layers.

[0024] The weft winding method with different warp yarn layers in the reduced layer zone refers to the method of winding to the area with fewer weft yarn layers in different areas of the same height of the fabric, and the weft yarn is wound out from the surface of the area, with the unwound part close to the outer surface layer.

[0025] Furthermore, each of the layered braiding machines is provided with a heald frame beam and a number of frame strips, the top of each frame strip is installed on the heald frame beam, and the frame strip is installed perpendicular to the heald frame beam;

[0026] Each frame bar is provided with several hanging loops of different heights arranged in a single row. The yarns on each frame bar are woven to form their own warp rows. The warp yarns at different heights on the same frame bar are woven to form different layers of warp yarns inside and outside.

[0027] During weaving, the heald frame beams, following the designed movement, are distributed vertically. Then, following the order from the innermost layer to the outermost layer, the warp yarns of different frame strips at the same height are pulled up sequentially to form warp layers. Interlacing openings are exposed between warp layers at different heights for weft yarn winding. When winding the weft yarn, the weft yarn passes through the interlacing opening. After winding one layer of warp yarn at the same height, the same operation is repeated to pull up another layer of warp yarn at a different height for weft yarn winding, until one weft weave from the inside out is completed according to the design parameters.

[0028] The application of the weaving method described herein is for weaving fabrics with continuously variable thickness in the axial direction and / or fabrics with variable thickness in the circumferential direction.

[0029] The weaving method is used for manufacturing large-size variable-thickness rotary body preforms. The fabric is a rotary body with an outer contour that is conical, cylindrical, frustum-shaped, or other irregular shapes. The rotary body is a rotary cylinder whose outer contour axis and inner contour axis are different.

[0030] The yarn of the fabric is made of quartz fiber, carbon fiber, silicon carbide fiber, silicon nitride fiber, glass fiber, or aramid fiber.

[0031] By adopting the above technical solution, the weaving method of the eccentric rotating body thickness-gradient fabric of the present invention has the following beneficial effects: it can not only realize continuous thickness weaving in the axial direction, but also thickness weaving in the same cross section; the yarn specifications and number of layers have a large adjustable range, adapting to the weaving of preforms of different specifications with varying thickness, thus adapting to the manufacture of large-sized (e.g., inner diameter of two meters or even more) rotating body preforms with varying thickness. The interlayer structural connection strength of the fabric of the present invention is good. In view of the operability of the present invention in weaving large-sized (multiple yarns) rotating body fabrics, and the high-strength connection between layers of multi-layer fabrics, the fabric of the present invention is particularly suitable for use in products such as aircraft engine casings. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the fabric structure of the present invention;

[0033] Figure 2 This is a cross-sectional view of the fabric of the present invention along its own axial direction;

[0034] Figure 3 This is a cross-sectional view (top view) of the fabric of the present invention along its circumferential direction.

[0035] Figure 4 This is a fabric weaving section diagram of the fabric of the present invention;

[0036] Figure 5 This is a diagram showing the process before the hook is moved.

[0037] Figure 6 This is a diagram showing the hook after it has been moved.

[0038] Figure 5 and Figure 6 In the diagram, different colored blocks represent different areas;

[0039] Figure 6 In the middle, they correspond to Unit 4 and Unit 2, respectively;

[0040] Figure 7 This is a schematic diagram of the structure of another fabric of the present invention;

[0041] Figure 8 This is a cross-sectional view of another fabric of the present invention along the axial direction;

[0042] Figure 9 This is a schematic diagram of the yarn principle of the braided layer continuous braiding machine of the present invention;

[0043] Figure 10 This is a schematic diagram of the multi-layered warp yarns formed after the warp yarns on the frame strip of the present invention are woven together.

[0044] Figure 11 This is a schematic diagram of the weft insertion of one weft in this invention;

[0045] Figure 12 This is a schematic diagram of another weft insertion according to the present invention.

[0046] annotation: Represents the warp yarn; This represents the weft yarns that are threaded through the entire layer; This represents the weft yarn that is half-layered. Detailed Implementation

[0047] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0048] Example 1

[0049] like Figures 1-3 As shown, an eccentric rotating body with gradually varying thickness is depicted. This embodiment uses a fabric 29 with a conical outer contour as an example for explanation. In this embodiment, the rotating body is specifically a rotating cylinder with a conical shape. It should be noted that in this invention, the outer contour of the fabric can be conical, cylindrical, frustum-shaped, or other irregularly shaped rotating bodies. The following explanation uses a conical cylinder as an example of the rotating body of the fabric.

[0050] The axis (axis, with reference to the outer contour) of fabric 29 is not concentric with the axis of its weaving core. The thickness of fabric 29 varies gradually in both the longitudinal (i.e., axial) and circumferential (i.e., circumferential) directions. However, the outer circle (outer contour) of the transverse (i.e., circumferential) section 30 of fabric 29 is a regular circle. Its wall thickness varies continuously along the circumferential direction, and its cross-sectional thickness also varies continuously along the axial direction.

[0051] Fabric 29 is divided into a thick region 31 and a thin region 32. The thickness gradually and uniformly decreases from the thick region 31 to the thin region 32. The connecting surface (the line connecting the center of the thick region 31 and the center of the thin region 32 along the axial direction) is mirror-symmetrical (e.g., ...). Figure 4 As shown), the central axis of the outer contour of fabric 29 lies on a mirror symmetry plane.

[0052] The main weaving steps of the fabric of the present invention are as follows:

[0053] S1. Divide the target fabric into regions:

[0054] The main body of the target fabric is divided into regions according to different locations;

[0055] S2. Calculate the weaving parameters for each region.

[0056] The weaving parameters for each region are designed separately. Based on the required volume fraction, warp density, and weft density, the weaving parameters for each region are calculated, including the number of weft yarn plies, the number of weft yarn layers, the number of warp yarn plies, the number of warp yarn layers, and the number of warp yarn rows.

[0057] In terms of parameter design, such as volume fraction, number of warp and weft yarns, number of layers, number of columns, etc., each region is the same as its corresponding (mirror symmetrical) region. The volume content, number of warp and weft yarns, number of layers, etc. of different regions of the fabric need to be adjusted according to the region location.

[0058] S3: Adjust the weaving parameters for each area.

[0059] First, determine the number of weft yarns, then adjust the total number of warp yarns. Then, based on the warp density, obtain the total number of warp yarns and the number of rows in each area, and then obtain the total number of yarns in a single row. Finally, based on the preset number of warp layers, obtain the total number of warp yarns.

[0060] Finally, make overall adaptive adjustments: adjust the number of warp plies to achieve a uniform transition in circumferential thickness, adjust the number of warp rows to match the warp density, and adjust the number of warp layers and plies to achieve a uniform transition in axial thickness.

[0061] S4. Knitting Work

[0062] First, fix the core mold, and then use the rotary body layered weaving technology to prepare a large-size variable diameter and variable thickness rotary body chamber. During the rotary body layered weaving, several layered weaving machines are used to perform layered weaving operations on each area. After processes such as yarn feeding, material cutting, yarn hanging, combing and weaving, the woven fabric is made. When the woven fabric reaches the target length, it can be removed from the weaving core mold.

[0063] Specifically, the mandrel is cone-shaped, which facilitates the formation of a conical inner cylinder by the fabric. Several layered knitting machines are arranged around the mandrel, with each layered knitting machine corresponding to one of the areas of the product.

[0064] The yarn preparation process involves confirming the accuracy of the frame bar (with yarn hanging rings on the frame bar for hanging yarn) and markings on the layered braiding machine (each layered braiding machine has its own markings, and it is necessary to verify whether the markings of the layered braiding machines correspond to their respective braiding areas), the correctness of the machine arrangement and boundaries (whether the arrangement of the layered braiding machines is correct, whether the yarns between adjacent layered braiding machines are tangled, etc.), and confirming the design parameters such as the number of warp layers, number of rows, length, and quantity.

[0065] like Figure 9As shown, each layer of the continuous knitting machine includes a heald frame beam a and several frame strips b. The top of each frame strip b is mounted on the heald frame beam a, and the frame strips b are installed perpendicular to the heald frame beam a. The number of heald frame beams a can be set according to the knitting unit, etc., and is not limited here. Figure 9 Taking two heddle frame beams (a) as an example, during weaving, the corresponding heddle lifting action can be designed according to the structure of the weaving unit. Figure 9 The diagram shows the lifting of one of the heald frame beams a. That is, the two heald frame beams a are woven in an up-down state. In this embodiment, after weaving one weft, the two heald frame beams a that were originally in an up-down state are adjusted to a down-up state and the weaving of the next weft continues.

[0066] Each frame b has several hanging loops c of different heights arranged in a single row. One end of the yarn is tied to the hanging loop c, and the other end is fixed to the allowance area of ​​the core mold (in this embodiment, the allowance area is located at the top of the core mold). The yarns on different frame b are woven to form different warp rows. Several hanging loops c of different heights are used to tie the warp yarns. Warp yarns tied at different heights on the same frame b are woven to form different layers (different thicknesses) of warp yarns. For example, if six warp yarns are tied at different heights on a frame b, namely d1, d2, d3, d4, d5, and d6, then these six warp yarns (d1, d2, d3, d4, d5, and d6) are woven to form different woven layers on the rotating preform from the inside out (e.g., Figure 10 As shown), together they form a multi-layered rotating body of a certain thickness.

[0067] In this embodiment, the number of frame strips b matches the number of weaving rows of the warp yarns in the preform of the rotating body, and the total number of layers from the inside out of the same warp row matches the number of hanging rings (i.e., warp yarns) set at different heights on the same frame strip b. It should be noted that in this invention, the warp yarns can be tied to the hanging rings c by traction ropes. These warp yarns are usually multi-strand yarns twisted together and tied to the hanging rings c. Each twisted warp yarn is considered a single braided yarn.

[0068] During weaving, a layered weaving machine is used to weave using a 2.5D weaving method. The warp yarns are hung on the yarn loops on the frame bars of the weaving machine according to calculated parameters. Each time weaving, the heald frame beams, after their designed operation, are distributed vertically. Following the order from the innermost to the outermost layer of the rotating preform, the warp yarns of different frame bars at the same height are sequentially pulled up to form warp layers. Interlacing openings are exposed between the warp layers for weft winding. During weft winding, the weft yarn passes through the interlacing opening. After winding one warp layer at the same height, this layer becomes the innermost layer of the preform. The same operation is repeated, pulling up the next layer (or the next layer below) of warp yarns to wind the weft yarn, making this layer the next innermost layer of the preform (interlaced with the innermost layer), until a single weft weave from the inside out is completed according to the design parameters (see weft insertion diagram). Figure 11 (As shown), then adjust the heddle lifting state and proceed with the weft weaving of the next weft. The weft insertion diagram is shown below. Figure 12 As shown.

[0069] During the weaving process, the parameters calculated and designed are processed in different areas, including but not limited to adding or subtracting yarn rows, adding or subtracting the number of yarn plies, and adding or subtracting the number of layers.

[0070] In a preferred embodiment, in step S4, the method for changing the thickness of the rotating body chamber is specifically a combination of one or more (at least two) of the following: variable warp yarn ply count, variable warp yarn layer count, and variable weft yarn ply count.

[0071] In a preferred embodiment, in step S1, because the fabric is mirror-symmetrical along the line connecting the thick region 31 and the thin region 32, and the thickness changes slowly, the fabric is divided into zones according to different positions. For example... Figure 4 As shown, the fabric is divided into 28 large sections, numbered sequentially as area 1 to area 28, each corresponding to one of the 28 layer-by-layer knitting machines. Each large section is further divided into two adjacent smaller sections, A and B, for a total of 56 smaller sections. For example, in the large sections, area 1 and area 28 are mirror images of each other, area 2 and area 27 are mirror images of each other, and so on, as shown in Table 1.

[0072]

[0073] In a preferred embodiment, in step S1, when dividing the fabric area, the height is divided into 5 mm sections according to the trend of the change in the circumferential cross-sectional area of ​​each section in the fabric height direction (axial direction) (i.e., the thickness difference).

[0074] In a preferred embodiment, in step S2, the parameters for different regions are calculated based on the requirement of a 54% volume fraction for each region, according to the formula... Calculate the required parameters. Inner arc length is s1 (mm), outer arc length is s2 (mm), area is S (mm²), warp density is j (threads / cm), weft density is k (threads / cm), number of layers is o, total number of warp threads is z, number of weft plies is n, warp shrinkage is δ, V f Here, ρ is the volume fraction, t is the fiber linear density, and ρ is the fiber bulk density. For example, region 1A at a height of 150 mm in thin section 32 has a cross-sectional area of ​​approximately 98.93 mm². 2 The inner arc length is 20.20 mm, and the outer arc length is 20.74 mm. The warp density j = 9 threads / cm = 0.9 threads / mm, and the weft density k = 2.3 threads / cm = 0.23 threads / mm. The quartz fiber parameters...

[0075] (t=190g / km=1.9x10) -4 g / mm, ρ=2.2g / cm 3 =2.2x10 -3 g / mm 3 Substituting this into the equation, this area (thin zone 32) is relatively thin, but single-strand quartz fiber weaving is difficult (because the thickness of the preform of the rotating body is fixed, single-strand weaving may lead to problems such as excessively dense and thick weft yarns). We use 2 warp strands and 5 weft strands (consistent with thick zone 31), with a warp shrinkage rate of 1.05. Taking all factors into account, we set the warp layer count to 9 layers: 3 strands on the inner and outer surfaces, 1 layer of 3 strands on the outer surface (2 layers total), and 2 strands in the remaining portion, resulting in a volume content of 56.48%, close to the required value. We calculate the parameters for each region in this manner.

[0076] It should be noted that, for ease of operation in production, the number of warp layers in different regions should generally not be set too high, typically less than 30 layers, and the difference in the number of weft layers between adjacent regions should be less than 3 layers. The number of weft layers is based on thin zone 32; therefore, the difference between the number of weft layers in thick zone 31 and thin zone 32 should not exceed 3 layers. Simultaneously, the number of warp ply and weft ply in the rotating body should ideally not exceed 5 ply.

[0077] Furthermore, parameters are adjusted based on the location of the area. Adjustments are made based on the approximate number of warp layers, ply counts, and number of rows at each location on the fabric. Taking a height of 150mm as an example, thin zone 32 has only 9 warp layers, while its weft yarns are generally set to 10 layers. This is 2 fewer weft layers compared to thick zone 31, which has 11 warp layers and 12 weft layers. In this case, if the weft yarns in thin zone 32 are used to uniformly wind the weft yarns, then thick zone 31 needs to skip layers of weft yarns, leading to a reduction in the number of weft yarn layers and requiring an increase in the ply count of the warp yarns in thick zone 31. If the weft yarns in thick zone 31 are used to uniformly wind the weft yarns, then thin zone 32 repeats the weft yarn winding, increasing the number of weft yarn layers and requiring a corresponding reduction in the ply count. However, thin zone 32 typically has only 2 ply counts, making this difficult to achieve. The adaptive adjustment involves reducing the number of weft yarn layers in the thicker zone (31) to maintain a consistent weft yarn count. When the number of weft yarn layers is 10, the required volume fraction is 57%. According to the formula, with 19 warp yarns in zone 14B, the volume fraction is 56.29%, which is too low. The number of single-column ply counts (i.e., the total number of braided yarn fibers on each loop of the corresponding frame) in the thicker zone (31) is increased from 60 to 61, resulting in a volume fraction of 57.08%, close to the required value. Considering all factors, at a height of 150mm, the thicker zone (31) has 11 warp yarn layers and 2 fewer weft yarn layers, totaling 10 weft yarn layers; the thinner zone (32) has 9 warp yarn layers, totaling 10 weft yarn layers. Based on this method, the number of warp and weft yarn layers in each zone is adjusted.

[0078] Specifically, based on the number of warp rows and ply counts in each area of ​​the fabric, as well as the number of warp rows and the total number of warp yarns per row at each height, the corresponding reduction positions for each area are configured. Taking the 150mm height as an example again, in area 1A, the number of warp layers is reduced from 10 to 9, during which one layer of 2-ply warp yarns is removed, which can be placed in the inner 3 layers. However, at 50mm, if the weft yarn has 11 layers, the volume content becomes 59.79%, approaching the critical value. Therefore, the weft yarn is set to 10 layers, reducing the content to 57.81%, which meets the requirements. In area 14B, similarly, from 50mm to 100mm, the warp yarn changes from 12 layers to 11 layers, losing one layer of 6-ply yarns, and the number of ply yarns per row decreases from 67 to 61. If the weft yarn at 50mm remains consistent with the thin area 32 at 10 layers, the volume content is 56.55%, which is too low. Adding one layer brings it to 57.39%, which is more in line with the requirements. The operation for the remaining areas is similar.

[0079] It should be noted that (1) the reduction of layers should be set within 3 layers on the inner and outer surfaces as much as possible, and the reduction of layers on the same layer of the continuous braiding machine should be in the same position to ensure good consistency. Adjacent layers of continuous braiding machines should avoid reducing layers on the inner surface or the outer surface at the same time, and when reducing layers at the same height, the same number of layers should be maintained as much as possible to avoid too many reduction positions and cause confusion.

[0080] (2) According to the designed process parameters, allocate the number of warp layers and ply for each section of each machine. On the production line, tie the yarns in sequence according to the set parameter details and hang them on the yarn hanging ring. After all the yarns are tied, fix the yarns and start weaving from this starting position. Therefore, the reasonable parameter design of the starting weaving position means that the number of warp ply in the starting part should not be too many, preferably less than 7 ply. On the one hand, too many warp ply will make it difficult to eliminate the traces left by the reduction of layers and ply, and on the other hand, too many warp ply will make it difficult to achieve the target weft density.

[0081] In a preferred embodiment, in step S4, the fabric setup for the continuous knitting machine involves initially arranging 28 continuous knitting machines. Each machine is divided into sections A and B, each with two different warp ply counts, resulting in 56 different warp ply counts across the 28 machines. To avoid significant differences in ply counts between the continuous knitting machines, which could cause unevenness in the fabric, a transition zone is created. The original single ply count for each section A or B is adjusted to a maximum of three ply counts, transforming the area into a low-ply zone – a normal-ply zone – a high-ply zone. This achieves a smooth transition between sections A and B, minimizing unevenness in the fabric due to varying ply counts.

[0082] In step S4 of the weaving process, yarn reduction refers to the reduction of layers or strands when the fabric height reaches a certain position. Because there is a height difference between the inside and outside of the fabric (different areas), the number of layers reduced near the inner surface is determined by the internal height, and the number of layers reduced on the outer surface is determined by the external height. When reducing an inner layer, all the outer yarns of the layer to be reduced move inward by one layer, achieving the removal and merging of one layer. When reducing an outer layer, the inner layer portion of the layer to be reduced must move outward by one layer as a whole, and the weft yarn is wound using different weft yarn winding methods for different warp yarn layers. In this invention, such as... Figure 11 and Figure 12 As shown, the weft winding method for different warp yarn layers in the reduced layer zone refers to winding the weft yarn to a region with fewer weft yarn layers in different areas of the same height of the fabric, with the weft yarn coming out from the surface of that region and the unwound part as close as possible to the outer surface layer.

[0083] In this invention, "adding yarns" refers to the need to add pairs of yarns to the outside of each layered knitting machine to match the interfaces between adjacent areas as the outer diameter of the rotating body increases during the knitting process.

[0084] In this invention, the knitting machines are arranged in a total of 28 layered knitting machines according to the divided large areas, and are numbered to correspond to the divided large areas. After the transition area is knitted, the hooks are moved. The yarn of every two layered knitting machines is combined into one knitting machine, reducing the number of knitting machines by half and reducing the difficulty of operation.

[0085] In this invention, the "hook shifting" method involves moving the yarn to reduce the number of machines from 28 to 14. The specific method is as follows:Figure 5 and Figure 6 As shown, move the warp yarns of even-numbered layer knitting machines to the upper layer of odd-numbered layer knitting machines that are one size smaller. For example, move the warp yarns of machine 2 to the upper layer of machine 1, and machine 4 to the upper layer of machine 3. Figure 6 As shown.

[0086] Example 2

[0087] Unlike Implementation Case 1, such as Figure 7 and Figure 8 As shown, the shape of this implementation case is cylindrical, but the weaving steps, weaving zoning principle, weaving parameter calculation method for each zone, yarn addition / reduction method, and layer addition / reduction method are all the same as in implementation case 1.

[0088] The above embodiments and accompanying drawings are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A method for weaving an eccentric rotating body thickness-gradient fabric, characterized in that: Includes the following steps: S1: Divide the target fabric into regions The main body of the target fabric is divided into regions according to different locations; S2: Calculate the weaving parameters for each region. Based on the required volume fraction, warp density, and weft density, the weaving parameters for each region are calculated, including the number of weft yarn plies, the number of weft yarn layers, the number of warp yarn plies, the number of warp yarn layers, and the number of warp yarn rows. In step S2, according to the formula Calculate the required parameters: S1 is the inner arc length, S2 is the outer arc length, S is the area, j is the warp density, k is the weft density, o is the number of layers, z is the total number of warp yarns in a single row, n is the number of weft plies, δ is the warp shrinkage rate, and V... f ρ is the volume fraction, t is the fiber linear density, and ρ is the fiber bulk density. S3: Adjust the weaving parameters for each area. First, determine the number of weft yarn plies, then adjust the total number of warp yarns. Then, based on the warp density, obtain the total number of warp yarns and the number of rows in each area. Next, obtain the total number of warp yarns in a single row. Finally, based on the designed number of warp layers, obtain the number of warp yarn plies. Finally, make overall adaptive adjustments: adjust the number of warp plies to achieve a uniform transition in circumferential thickness, adjust the number of warp rows to match the warp density, and adjust the number of warp layers and plies to achieve a uniform transition in axial thickness. S4: Knitting Work First, fix the core mold, and then use several layered braiding machines to perform layered braiding operations on each area. The process involves yarn preparation, cutting, yarn hanging, combing, and braiding. During the braiding process, the thickness is adjusted in different areas according to the calculated parameters, including adding or subtracting the number of yarn rows, adding or subtracting the number of yarn plies, and adding or subtracting the number of layers. Finally, the fabric is obtained, and the warp yarns and weft yarns of each layer of the fabric are woven together. In step S3, firstly, based on the calculated number of warp layers in each region, the number of single-row ply of warp yarns in each layer, and the number of warp rows, the number of weft yarn layers in the thin area is reduced to maintain a consistent number of weft yarns in the fabric, using the number of weft yarn layers in the thin area as a unified standard. Then, based on the set volume fraction, the number of warp yarn layers and the number of single-row ply of warp yarns in each layer are adjusted to meet the set volume fraction.

2. The weaving method for an eccentric rotating body thickness-gradient fabric as described in claim 1, characterized in that: In step S1, the fabric is divided into sections according to different heights. The height is divided into sections every M mm according to the trend of the change of the circumferential cross-sectional area of ​​each section in the height direction, where M is 5-10 mm. In step S2, when calculating the parameters of each region, the number of weft yarn layers in the thin region is used as the benchmark. Based on this, the difference between the number of weft yarn layers in the thick region and the number of weft yarn layers in the thin region shall not exceed three layers, and the total number of plies of warp and weft yarns shall not exceed seven.

3. The weaving method of an eccentric rotating body thickness-gradient fabric as described in claim 1, characterized in that: When designing warp reduction layers, the reduction layer position is set within three layers of the inner and outer surfaces of the fabric. The reduction layer position is the same for the same layer on the continuous knitting machine, and the same number of layers is maintained when reducing layers at the same height.

4. The weaving method of an eccentric rotating body thickness-gradient fabric as described in claim 1, characterized in that: Each of the layered braiding machines is provided with a heald frame beam and a number of frame strips. The top of each frame strip is installed on the heald frame beam, and the frame strip is installed perpendicular to the heald frame beam. Each frame bar is provided with several hanging loops of different heights arranged in a single row. The yarns on each frame bar are woven to form their own warp rows. The warp yarns at different heights on the same frame bar are woven to form different layers of warp yarns inside and outside. During weaving, the heald frame beams, following the designed movement, are distributed vertically. Then, following the order from the innermost layer to the outermost layer, the warp yarns of different frame strips at the same height are pulled up sequentially to form warp layers. Interlacing openings are exposed between warp layers at different heights for weft yarn winding. When winding the weft yarn, the weft yarn passes through the interlacing opening. After winding one layer of warp yarn at the same height, the same operation is repeated to pull up another layer of warp yarn at a different height for weft yarn winding, until one weft weave from the inside out is completed according to the design parameters.

5. The application of the weaving method as described in any one of claims 1 to 4, characterized in that: The weaving method is used for weaving fabrics with continuously variable thickness in the axial direction and / or fabrics with variable thickness in the circumferential direction. The weaving method is used for manufacturing large-size variable-thickness rotary body preforms. The fabric is a rotary body with an outer contour that is conical, cylindrical, frustum-shaped, or other irregular shapes. The rotary body is a rotary cylinder whose outer contour axis and inner contour axis are different.

6. The application of the weaving method as described in claim 5, characterized in that: The yarn of the fabric is made of quartz fiber, carbon fiber, silicon carbide fiber, silicon nitride fiber, glass fiber, or aramid fiber.

Images