Knitting method and application of eccentric revolving body fabric with gradually-changed thickness

Abstract

The invention belongs to the technical field of three-dimensional weaving, and discloses a weaving method and application of an eccentric revolving body fabric with gradually-changed thickness, and the weaving method comprises the following steps: 1, dividing a target fabric into areas; 2, parameter design: according to the required volume fraction, warp density and weft density, calculating to obtain knitting parameters of each area, including the weft yarn combined strand number, the weft yarn layer number, the warp yarn combined strand number, the warp yarn layer number and the warp yarn column number; 3, determining the number of strands of the weft yarns, adjusting the total number of the warp yarns, obtaining the total number of the warp yarns and the column number of each area according to the warp density, obtaining the total number of the warp yarns in a single column, and obtaining the number of strands of the warp yarns according to the designed number of layers of the warp yarns; and finally, carrying out overall adaptability adjustment. And 4, weaving by adopting a layer connection weaving technology. According to the method, continuous variable-thickness weaving in the axial direction can be achieved, and variable-thickness weaving of the same cross section can also be achieved; and the method can be suitable for manufacturing large-size variable-thickness rotary body prefabricated bodies of different specifications.

Description

Technical Field

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

[0002] The application of high-performance fiber-reinforced composite materials in the fields of aerospace and national defense has received more and more attention. The body of revolution preform is a commonly used reinforcement for high-performance fiber-reinforced composite materials. The body of revolution preform is usually prepared by three-dimensional integral weaving (such as the method disclosed in CN106400295A) and circular three-dimensional weaving method (such as the method disclosed in CN101811365A). However, these methods are limited by the weaving method and are only applicable to the preparation of small-sized preforms, usually with a diameter limited to within 500mm, and a large amount of yarn needs to be arranged during manufacturing. The loom occupies a large area, the number of manual labor is large, the process is complicated, and the manufacturing efficiency is low. For the preparation of large-sized variable thickness body of revolution 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 molding is greater, which cannot be achieved by the above method at present.

[0003] Regarding the high-thickness rotor weaving forming method, patent CN112877862A "Preparation method of rotor preform and rotor preparation method" and patent CN108004650B "Large-size variable-thickness rotor preform and preparation method thereof" are both aimed at rotors with varying thickness, but they are both methods for the same cross-section with the same thickness, and the weaving method for rotors with varying thickness of the same cross-section is not mentioned. Moreover, the method for realizing high-thickness rotors in both technologies is to superimpose multiple layers of woven two-dimensional fabrics and wind them on a rotor core mold to form a high-thickness rotor. Adjacent layers of fabric are simply stacked together, and there is no fiber connection in the thickness direction. The interlayer performance is weak and it is easy to delaminate, which is suitable for structural parts with low requirements for interlayer performance.

[0004] In view of this, the inventor of this case conducted in-depth research, which resulted in the creation of this case. Summary of the invention

[0005] The object of the present invention is to overcome the above limitations and provide a weaving method and application of eccentric rotating body thickness gradient fabrics suitable for large size and / or multi-dimensional thickness changes.

[0006] In order to achieve the above object, the technical solution of the present invention is: A method for weaving an eccentric rotating body thickness gradient fabric comprises the following steps: S1: Divide the target fabric into areas Divide the main body of the target fabric into regions according to different positions; S2: Calculate the knitting parameters of each area According to the required volume fraction, warp density and weft density, the weaving parameters of each area 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 s1, 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, n is the number of weft yarns, δ is the warp yarn shrinkage, Vf is the volume fraction, t is the fiber linear density, and ρ is the fiber body density; S3: Adjust the knitting parameters of each area First, determine the number of weft yarns, then adjust the total number of warp yarns, and then get the total number of warp yarns and rows in each area according to the warp density, and then get the total number of single rows, and then get the number of warp yarns according to the designed number of warp yarn layers; Finally, make overall adaptability adjustments: adjust the number of warp yarns to achieve uniform transition of circumferential thickness changes, adjust the number of warp yarn rows to match the warp density, and adjust the number of warp yarn layers and plies to achieve uniform transition of axial thickness changes; S4: Weaving First, the core mold is fixed, and then a number of layer-linked weaving machines are used to carry out layer-linked weaving operations on each area, and the operations of laying yarn, unloading, tying yarn, combing and weaving are carried out in sequence. During the weaving process, thickness change processing is carried out in different areas according to the calculated parameters, including adding or subtracting the number of yarn columns, adding or subtracting the number of yarn strands and adding or subtracting the number of layers, and finally a fabric is obtained, in which each layer of warp yarn and each layer of weft yarn are woven together in layers.

[0007] Furthermore, in step S3, first, based on the calculated number of warp yarn layers in each area, the number of single-row twists of warp yarns in each layer, and the number of warp yarn columns, the number of weft yarn layers in the thin area is used as a unified standard, and the number of weft yarn layers in the thick area is reduced to maintain a consistent number of weft yarns in the fabric as a benchmark, and then based on the set volume fraction, the number of warp yarn layers and the number of single-row twists of warp yarns in each layer are adjusted to meet the set volume fraction. Further, in step S1, the fabric is divided into zones according to different heights, and the height zones are divided into M mm according to the change trend of the annular cross-sectional area of ​​each zone in the height direction, and M is 5-10 mm; In step S2, when calculating the parameters of each area, the number of weft yarn layers in the thin area is used as a reference. On this basis, the difference between the number of weft yarn layers in the thick area and the number of weft yarn layers in the thin area does not exceed three, and the number of warp yarns and weft yarns does not exceed seven.

[0008] Furthermore, when the warp yarn layer reduction is designed, the layer reduction position is set within three layers of the inner and outer surfaces of the fabric, the layer reduction position of the same layer is the same for the knitting machine, and when the layers are reduced at the same height, the same number of layers is maintained.

[0009] Furthermore, in the weaving process of step S4, yarn reduction is a layer or strand reduction operation performed when the fabric height reaches a certain position during the weaving process. Due to the height difference between the inside and outside of the fabric, the number of layers reduced close to 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 the inner layer, all the yarns of the outer layer corresponding to the number of layers reduced should be moved inward by one layer; when reducing the outer layer, the inner layer part of the reduced layer should be moved outward by one layer as a whole, and the weft yarn winding method with different warp yarn layers should be used to wind the weft yarn; The weft winding method with different numbers of warp yarn layers in the reduced-layer area refers to the weft yarn winding method with different numbers of weft yarn layers in different areas at the same height of the fabric. The weft yarn is wound to the area with fewer weft yarn layers, and the weft yarn is wound out from the surface of the area, and the empty wound part is close to the outer surface layer.

[0010] Furthermore, each of the layer-linked braiding machines is respectively provided with a heald frame crossbeam and a plurality of frame bars, the top of each of the frame bars is installed on the heald frame crossbeam, and the frame bars are installed perpendicular to the heald frame crossbeam; Each of the frame strips is provided with a plurality of yarn hanging rings of different heights and arranged in a single row. The yarns on each of the frame strips are woven to form respective warp yarn rows. The warp yarns at different heights tied on the same frame strip are woven to form different layers of warp yarns inside and outside. During weaving, the heald frame crossbeam is distributed up and down according to the designed operation. Then, the warp yarns at the same height of different frame strips are pulled up in sequence from the innermost layer to the outermost layer to form a warp yarn layer. The interlacing openings are exposed between the warp yarn layers at different heights, and the weft yarn is wound. When winding the weft yarn, the weft yarn is passed through the interlacing opening. After winding a layer of warp yarns at the same height, the same operation is repeated to pull up the warp yarn layer at another height to wind the weft yarn, until the weft weaving from the inside to the outside is completed according to the design parameters.

[0011] Application of the weaving method, wherein the weaving method is used for weaving a fabric with continuously variable thickness in the axial direction and / or a fabric with variable thickness in the circumferential direction; The weaving method is used for manufacturing a large-size variable-thickness rotating body preform, wherein the fabric is a rotating body with a conical, cylindrical, truncated cone or other special-shaped outer contour, and the rotating body is a rotating cylinder with different outer contour axes and inner contour axes.

[0012] The yarn of the fabric is quartz fiber, carbon fiber, silicon carbide fiber, silicon nitride fiber, glass fiber or aramid fiber.

[0013] After adopting the above technical scheme, 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 variable thickness weaving in the axial direction, but also realize variable thickness weaving of the same cross-section; the yarn specifications and the number of layers can be adjusted in a large space, which is suitable for the weaving of variable thickness preforms of different specifications, and thus suitable for the manufacture of large-sized (such as cylinder inner diameter of two meters or even more than two meters) variable thickness rotating body preforms of different specifications. The interlayer structure connection strength of the fabric of the present invention is good. In view of the operability of the present invention in weaving large-sized (more 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic structural diagram of the fabric of the present invention; Figure 2 is a cross-sectional view of the fabric of the present invention along its own axial direction; Figure 3 is a cross-sectional view (top view) of the fabric of the present invention along its circumferential direction; Figure 4 A fabric weave partition diagram of the fabric of the present invention; Figure 5 This is a schematic diagram before moving the hook; Figure 6 This is a schematic diagram after moving the hook; Figure 5 and Figure 6 In the figure, blocks of different colors represent different areas; Figure 6 In the example, they correspond to machine No. 4 and machine No. 2 respectively; Figure 7 It is a schematic diagram of the structure of another fabric of the present invention; Figure 8 is a cross-sectional view of another fabric of the present invention along the axial direction; Fig. 9 It is a schematic diagram of the yarn principle of the braided layer and the braiding machine of the present invention; Fig.10 It is a schematic diagram of the multi-layer warp yarns formed after the warp yarns on the frame strips of the present invention are woven; Fig.11 It is a schematic diagram of weft threading of one weft of the present invention; Fig.12 It is a schematic diagram of weft threading of another weft of the present invention.

[0015] annotation: represents the warp; It represents the weft yarn that is worn through the entire layer; It represents wearing half a layer of weft yarn. DETAILED DESCRIPTION

[0016] In order to further explain the technical solution of the present invention, the present invention is described in detail below through specific embodiments.

[0017] Example 1 like Figure 1~Figure 3 As shown, a eccentric rotating body thickness gradient fabric. This embodiment is described by taking a fabric 29 with a conical outer contour as an example. In this embodiment, the rotating body is specifically a rotating cylinder with a tapered cylinder. It should be noted that in the present invention, the outer contour of the fabric can be a conical, cylindrical, truncated cone or other special-shaped rotating body. The following description is taken as an example of a fabric rotating body being a tapered cylinder.

[0018] The axis (axial line, with the outer contour as a reference) of the fabric 29 is not concentric with the axis of its weaving core mold. The thickness of the fabric 29 changes gradually in the longitudinal direction (i.e., axial direction) and the annular direction (i.e., circumferential direction). However, the outer circle (outer contour) of the transverse (i.e., circumferential) cross section 30 of the fabric 29 is a regular circle, and its wall thickness changes continuously along the circumferential direction, and the cross-sectional thickness along the axial direction also changes continuously. The fabric 29 is divided into a thick area 31 and a thin area 32. The thickness gradually and evenly decreases from the thick area 31 to the thin area 32. The connecting line (connecting surface) of the thin area 32 and the thick area 31 along the center position (along the axial direction) of the thick area 31 and the center position (along the axial direction) of the thin area 32 is mirror-symmetrical (e.g. Figure 4 As shown in FIG. 2 ), the central axis of the outer contour of the fabric 29 is located on the mirror symmetry plane.

[0019] The main weaving steps of the fabric of the present invention are as follows: S1. Divide the target fabric into regions: Divide the main body of the target fabric into regions according to different positions; S2. Calculate the knitting parameters of each area The weaving parameters of each area are designed respectively, and the weaving parameters of each area are calculated according to the required volume fraction, warp density and weft density, 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 parameter design, such as volume fraction, number of warp and weft yarns, number of layers, number of columns, etc., each area is the same as its corresponding (mirror-symmetric) area. The volume content, number of warp and weft yarns, number of layers, etc. of different areas of the fabric need to be adjusted according to the regional position.

[0020] S3: Adjust the knitting parameters of each area First, determine the number of weft yarns, then adjust the total number of warp yarns, and then get the total number of warp yarns and rows in each area according to the warp density, and then get the total number of single rows, and then get the number of warp yarns according to the preset number of warp yarn layers; Finally, make overall adaptive adjustments: adjust the number of warp yarns to achieve a uniform transition in circumferential thickness, adjust the number of warp yarn rows to match the warp density, and adjust the number of warp yarn layers and plies to achieve a uniform transition in axial thickness.

[0021] S4. Weaving work First fix the core mold, and then use the rotary body layer-by-layer weaving technology to prepare a large-size rotary body warehouse with variable diameter and thickness. When the rotary body is layer-by-layer weaving, a number of layer-by-layer weaving machines are used to carry out layer-by-layer weaving operations on each area. The braided fabric is made through process technologies such as yarn laying, material cutting, yarn tying, combing and weaving. When the braided fabric reaches the target length, it can be removed from the braiding core mold.

[0022] Specifically, the core mold is in a cone shape, so that the fabric can form a cone inner cylinder. A plurality of layer-linked braiding machines are arranged around the core mold, and each layer-linked braiding machine is arranged one by one corresponding to each area divided by the product.

[0023] Yarn laying is the process of confirming the setting of the frame bars of the layered weaving machines (there are yarn hanging rings on the frame bars, which are used to hang yarn), the accuracy of the identification setting (each layered weaving machine is equipped with a logo, and it is necessary to check whether the logo of the layered weaving machines corresponds to their respective weaving areas), the correctness of the arrangement of the machines and the junctions (whether the arrangement positions of the layered weaving machines are correct, whether the yarns between adjacent layered weaving machines are entangled, etc.), and confirming the design parameters such as the number of warp layers, number of columns, length and quantity. like Fig. 9 As shown, each layer-linked braiding machine comprises a heald frame beam a and a plurality of frame bars b, the top of each frame bar b is mounted on the heald frame beam a, and the frame bars b are installed perpendicular to the heald frame beam a. The number of heald frame beams a can be set according to considerations such as the braiding unit, and is not limited here. Fig. 9 Taking the case where the number of the heald frame cross beams a is two as an example, during weaving, the corresponding heald lifting action can be designed according to the structure of the weaving unit. Fig. 9 The figure shows a schematic diagram of lifting one of the heald frame beams a, that is, the two heald frame beams a are woven in an up-and-down state. In this embodiment, after weaving one warp, the two heald frame beams a that were originally "up-and-down" are adjusted to "down-and-up" respectively to continue weaving the next warp.

[0024] Each frame strip b is provided with a number of yarn hanging rings c which are of different heights and arranged in a single row. One end of the yarn is correspondingly tied to the yarn hanging ring c, and the other end of the yarn is fixed to the surplus area of ​​the core mold (the surplus area in this embodiment is arranged at the top of the core mold). The yarns on different frame strips b are woven to form different warp yarn rows. Several yarn hanging rings c of different heights are used to tie the warp yarns. The warp yarns at different heights tied on the same frame strip b are correspondingly woven to form warp yarns of different layers (different thickness positions). For example, six warp yarns at different heights are tied to a frame strip b, which are d1, d2, d3, d4, d5 and d6 respectively. Then, the six warp yarns (d1, d2, d3, d4, d5 and d6) are correspondingly woven to form the constituent warp yarns of different woven layers from the inside to the outside on the rotating body preform (such as Fig.10 As shown), together they constitute a multi-layer rotating body of a certain thickness.

[0025] In this embodiment, the number of frame strips b matches the number of braided columns of the braided (warp) yarns of the rotating body preform, and the total number of layers from the inside to the outside of the same warp column matches the number of yarn hanging rings (i.e., warp yarns) arranged at different heights on the corresponding frame strip b. It should be noted that in the present invention, the warp yarn can be tied to the yarn hanging ring c by a traction rope, and the warp yarn is usually a warp yarn after a plurality of yarn fibers are plied together, and is tied to the yarn hanging ring c after plied together, and a plied warp yarn is regarded as a braided yarn.

[0026] During weaving, a layer-linked weaving machine is used to weave according to the 2.5D weaving method. The warp yarns are hung on the yarn hanging rings on the frame bars of the weaving machine according to the calculated parameters. Each time weaving, the heald frame beam is distributed up and down according to the designed operation. Then, in the order from the innermost layer to the outermost layer of the rotating body preform, the warp yarns at the same height of different frame bars are pulled up in sequence to form a warp yarn layer. The interlacing opening is exposed between the warp yarn layer and the warp yarn layer, and the weft yarn is wound. When winding the weft yarn, the weft yarn passes through the interlacing opening. After winding a layer of warp yarns at the same height, this layer is used as the innermost layer of the preform, and then the same operation is repeated to pull up the next layer (or the next layer) of warp yarn and wind the weft yarn, and this layer is used as the sub-inner layer of the preform (interlaced and connected with the innermost layer), until the weft weaving from the inside to the outside is completed according to the design parameters (the weft threading schematic diagram is shown in the figure). Fig.11 As shown), then adjust the lifting state of the heald bar to weave the next weft. The weft insertion diagram is as shown Fig.12 shown.

[0027] During the weaving process, processing is performed in different areas according to the calculated and designed parameters, including but not limited to adding or subtracting yarn rows, adding or subtracting the number of yarn strands, adding or subtracting the number of layers, and other operations.

[0028] As a preferred implementation, in step S4, the method for changing the thickness of the rotating body bin is specifically a method combining one or more (at least two) of changing the number of warp yarn plies, changing the number of warp yarn layers and changing the number of weft yarn plies.

[0029] As a preferred embodiment, in step S1, since the fabric is mirror-symmetrical along the line connecting the thick area 31 and the thin area 32, the thickness changes slowly, and the fabric is divided into zones according to different positions. Figure 4 As shown in Figure 1, the fabric is specifically divided into 28 large areas, numbered as area 1 to area 28, corresponding to 28 layer-linked knitting machines. Each large area is divided into two adjacent small areas A and B, with a total of 56 small areas. For example, in the large area, area 1 is mirror-symmetrical with area 28, area 2 is mirror-symmetrical with area 27, and so on, as shown in Table 1.

[0030]

[0031] As a preferred implementation, in step S1, when the fabric area is divided, the height partition is performed every 5 mm according to the change trend (ie, thickness difference) of the annular cross-sectional area of ​​each partition in the height direction (axial direction) of the fabric.

[0032] As a preferred embodiment, in step S2, the calculation of parameters of different regions is based on the requirement of 54% volume fraction of each region, according to the formula Calculate the required parameters. The length of the inner arc is s 1 (mm), the outer arc length is s 2 (mm), area is S (mm²), warp density is j (roots / cm), weft density is k (roots / cm), number of layers is o, total number of warp yarns is z, number of weft yarns is n, warp shrinkage is δ, V f is the volume fraction, t is the fiber linear density, and ρ is the fiber body density. For example, the cross-sectional area of ​​the thin zone 32 at a height of 150 mm in the 1A region is about 98.93 mm 2 , the inner arc length is 20.20mm, and the outer arc length is 20.74mm. Among them, the warp density j=9 strands / cm=0.9 strands / mm, the weft density k=2.3 strands / cm=0.23 strands / mm, and the quartz fiber parameters (t=190g / km=1.9x10 -4 g / mm,ρ=2.2g / cm 3 =2.2x10 -3 g / mm 3) is brought in. Here (thin area 32) is thinner, but it is difficult to weave a single strand of quartz fiber (due to the fixed thickness of the rotating body preform, if a single strand is woven, it may cause problems such as too dense and too thick weft yarns). 2 strands of warp yarn, 5 strands of weft yarn (consistent with thick area 31), and a warp shrinkage of 1.05 are brought in. Comprehensive consideration is given to setting the number of warp yarn layers to 9, 3 strands on the inner and outer surfaces, 2 layers on the outer surface, a total of 1 layer of 3 strands, and 2 strands in the rest. The volume content is 56.48%, which is close to the required value. And so on, calculate the parameters of each area.

[0033] It should be noted that, in order to facilitate the operation in production, the number of warp yarn layers should not be set too much in the calculation of parameters of different regions, usually less than 30 layers, and the difference in the number of weft yarn layers between two adjacent regions should be less than 3 layers. The number of weft yarn layers is based on the thin area 32, and on this basis, the difference between the number of weft yarn layers in the thick area 31 and the number of weft yarn layers in the thin area 32 is no more than 3 layers. At the same time, the number of warp yarns and the number of weft yarns in the barrel of the rotating body should not exceed 5 as much as possible.

[0034] Furthermore, the parameters are adjusted according to the regional position, and further adjustments are made based on the approximate number of layers, number of strands and number of columns of the warp yarns at each position of the fabric. Taking the calculation result of a height of 150 mm as an example, there are only 9 layers of warp yarn in the thin zone 32, and its weft yarn is generally set to 10 layers, which is 2 layers less than the 11 layers of warp yarn and 12 layers of weft yarn in the thick zone 31. In this case, if the weft yarns are wound uniformly according to the number of weft yarns in the thin zone 32 during weaving, then the thick zone 31 needs to skip layers to wind the weft yarns, which will result in a decrease in the number of weft yarn layers, and the warp yarn strands of the thick zone 31 need to be increased; if the weft yarns are wound uniformly according to the number of weft yarns in the thick zone 31, and the weft yarns are repeatedly wound in the thin zone 32, the number of weft yarn layers increases, and the weft yarn strands need to be reduced accordingly, but the thin zone 32 is basically 2 strands here, which is not easy to achieve. Adaptability can be adjusted to reduce the number of weft yarn layers in thick area 31 to maintain the same number of weft yarns in the fabric. When the number of weft yarn layers is 10, the volume fraction requirement is 57%. According to the formula, when there are 19 rows of warp yarns in area 14B, the volume content is 56.29%, which is too small. Increase the number of single-row plies of warp yarns in area 14B of thick area 31 (that is, the sum of the number of woven yarn fiber roots on each hanging yarn ring on the corresponding frame strip) from 60 to 61, and the volume content of this area becomes 57.08%, which is close to the required value. Comprehensively considered, at a height of 150mm, there are 11 layers of warp yarns in thick area 31, 2 layers of weft yarns are less wound, and a total of 10 layers of weft yarns; there are 9 layers of warp yarns in thin area 32, and a total of 10 layers of weft yarns. According to this method, the number of warp yarn layers and weft yarn layers in each area are adjusted.

[0035] Specifically, according to the number of warp yarns and strands in each area of ​​the fabric, as well as the number of warp yarns at each height and the total number of warp yarns in a single row, the corresponding positions for reducing layers and strands in each area are configured. Take the height of 150mm as an example. In area 1A, the number of warp yarn layers here is reduced from 10 to 9, and 1 layer of 2 strands of warp yarns are reduced during the period, which can be set in the inner 3 layers. But at 50mm, if the weft yarn is 11 layers, the volume content becomes 59.79%, approaching the critical value, so the weft yarn is set to 10 layers, and the content is reduced to 57.81%, which meets the requirements. In area 14B, similarly, 50mm-100mm, the warp yarn changes from 12 layers to 11 layers, one layer of 6 strands is reduced, and the number of strands in a single row is reduced from 67 to 61. If the weft yarn at 50mm is consistent with the thin area 32 with 10 layers, the volume content is 56.55%, which is too small, and adding 1 layer is 57.39%, which is more in line with the requirements. The operation of the remaining areas is analogous.

[0036] It should be noted that (1) the layer reduction should be set within 3 layers on the inner and outer surfaces as much as possible, and the layer reduction position of the same layer of the knitting machine should be the same, so that the consistency is better. The adjacent layer knitting machines should try to avoid reducing the layer on the inner surface or the outer surface at the same time, and when reducing the layer at the same height, try to keep the same number of layers to avoid too many layers and confusion.

[0037] (2) According to the designed process parameters, the number of warp yarn layers and strands corresponding to each section of each machine is allocated. The yarns on the production line are tied and hung on the yarn hanging ring in turn according to the set parameter details. After all the yarns are tied, the yarns are fixed and weaving begins from this starting weaving position. Therefore, the reasonable parameter design of the yarn at the starting weaving position means that the number of warp yarn strands at the starting part should not be too many, preferably less than 7 strands. On the one hand, too many warp yarn strands will make it difficult to eliminate the traces left by operations such as reducing layers and strands. On the other hand, too many warp yarn strands will make it difficult to achieve the weft density target.

[0038] As a preferred embodiment, in the fabric of step S4, confirming the setting of the layered weaving machine frame strips is to arrange 28 layered weaving machines at the beginning, and each machine has 2 warp yarn ply numbers according to the A and B partitions, and 28 machines correspond to 56 warp yarn ply numbers. In order to avoid the large difference in the number of ply numbers between the layered weaving machines, resulting in steps in the fabric, a transition zone is arranged, and the original single ply number in each area of ​​area A or area B is adjusted to a maximum of 3 ply numbers as needed, becoming a small ply area-normal ply-multiple ply area. In this way, the number of ply A and B is adjusted to achieve a smooth transition, and the fabric is prevented from having high and low steps due to different ply numbers as much as possible.

[0039] In the weaving of step S4, yarn reduction means that when the fabric height reaches a certain position during the weaving process, a layer reduction or strand reduction operation is performed. Since there is a height difference between the inside and outside of the fabric (different areas), the number of layers reduced close to the inner surface is determined by the inner height, and the number of layers reduced on the outer surface is determined by the outer height: when reducing the inner layer, all the yarns of the outer layer of the reduced layer move inward by one layer, so that one layer can be removed and merged; when reducing the outer layer, the inner layer of the reduced layer should move outward by one layer as a whole, and the weft yarns are wound using the weft yarn winding method with different warp yarn layers; in the present invention, if Fig.11 and Fig.12 As shown, the weft winding method with different numbers of warp yarn layers in the reduced layer area refers to winding the weft yarns to the area with fewer weft yarn layers in different areas at the same height of the fabric, and the weft yarns are wound out from the surface of the area, and the empty wound part is as close to the outer surface layer as possible.

[0040] In the present invention, adding rows means that during the weaving process, as the outer diameter of the rotary bin increases, pairs of yarns need to be added to the outside of each layer-linked weaving machine to match the interface between adjacent areas.

[0041] In the present invention, the arrangement of the machines is to arrange a total of 28 layer-connected knitting machines according to the divided areas, and number them corresponding to the divided areas. After the transition area is knitted, the hook is moved, and the yarns of every two layer-connected knitting machines are merged into one knitting machine, reducing half of the knitting machines and reducing the difficulty of operation.

[0042] In the present invention, the hook-moving method is to change the original 28 machines into 14 machines by moving the yarn. The specific method is as follows: Figure 5 and Figure 6 As shown, move the warp yarn of the even-numbered knitting machine to the upper layer of the odd-numbered knitting machine that is one size smaller than it. For example, move the warp yarn of the No. 2 machine to the upper layer of the No. 1 machine, and the No. 4 machine to the upper layer of the No. 3 machine. Figure 6 shown.

[0043] Example 2 Different from Implementation Case 1, Figure 7 and Figure 8 As shown, the shape of this implementation case is cylindrical, but the weaving steps, weaving zoning principles, weaving parameter calculation methods for each zone, yarn addition and subtraction methods, layer addition and subtraction methods, etc. are the same as those in implementation case 1.

[0044] The above embodiments and drawings do not limit the product form and style of the present invention. Any appropriate changes or modifications made thereto by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present invention.

Claims

1. A method for weaving a fabric with a gradual thickness change of an eccentric rotating body, characterized in that: The steps include: S1: Divide the target fabric into areas Divide the main body of the target fabric into regions according to different positions; S2: Calculate the knitting parameters of each area According to the required volume fraction, warp density and weft density, the weaving parameters of each area 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 s1, 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, n is the number of weft yarns, δ is the warp shrinkage, V f is the volume fraction, t is the fiber linear density, and ρ is the fiber body density; S3: Adjust the knitting parameters of each area First, determine the number of weft yarns, then adjust the total number of warp yarns, and then get the total number of warp yarns and rows in each area according to the warp density, and then get the total number of single rows, and then get the number of warp yarns according to the designed number of warp yarn layers; Finally, make overall adaptability adjustments: adjust the number of warp yarns to achieve uniform transition of circumferential thickness changes, adjust the number of warp yarn rows to match the warp density, and adjust the number of warp yarn layers and plies to achieve uniform transition of axial thickness changes; S4: Weaving First, the core mold is fixed, and then a number of layer-linked weaving machines are used to carry out layer-linked weaving operations on each area, and the operations of laying yarn, unloading, tying yarn, combing and weaving are carried out in sequence. During the weaving process, thickness change processing is carried out in different areas according to the calculated parameters, including adding or subtracting the number of yarn columns, adding or subtracting the number of yarn strands and adding or subtracting the number of layers, and finally a fabric is obtained, in which each layer of warp yarn and each layer of weft yarn are woven together in layers.

2. A method for weaving a eccentric rotating body thickness gradient fabric as claimed in claim 1, characterized in that: In step S3, first, based on the calculated number of warp yarn layers in each area, the number of single-row twists of warp yarns in each layer, and the number of warp yarn columns, the number of weft yarn layers in the thin area is used as a unified standard to reduce the number of weft yarn layers in the thick area, in order to maintain the consistency of the number of weft yarns in the fabric. Then, based on the set volume fraction, the number of warp yarn layers and the number of single-row twists of warp yarns in each layer are adjusted to meet the set volume fraction.

3. The weaving method of the eccentric rotating body thickness gradient fabric according to claim 1, characterized in that: In step S1, the fabric is divided into zones according to different heights, and the height zones are divided into M mm according to the change trend of the annular cross-sectional area of ​​each zone in the height direction, and the value of M is 5-10 mm; In step S2, when calculating the parameters of each area, the number of weft yarn layers in the thin area is used as a reference. On this basis, the difference between the number of weft yarn layers in the thick area and the number of weft yarn layers in the thin area does not exceed three, and the number of warp yarns and weft yarns does not exceed seven.

4. The weaving method of the eccentric rotating body thickness gradient fabric according to claim 1, characterized in that: When the warp yarn layer reduction is designed, the layer reduction position is set within three layers of the inner and outer surfaces of the fabric, the layer reduction position of the same layer is the same for the knitting machine, and when the layers are reduced at the same height, the same number of layers is maintained.

5. The weaving method of the eccentric rotating body thickness gradient fabric according to claim 1, characterized in that: In the weaving process of step S4, yarn reduction is a layer or strand reduction operation performed when the fabric height reaches a certain position during the weaving process. Since there is a height difference between the inside and outside of the fabric, the number of layers reduced close to the inner surface is determined by the inner height, and the number of layers reduced on the outer surface is determined by the outer height; When reducing the inner layer, all the yarns of the outer layer corresponding to the number of layers reduced should be moved inward by one layer; when reducing the outer layer, the inner layer part of the reduced layer should be moved outward by one layer as a whole, and the weft yarn winding method with different warp yarn layers should be used to wind the weft yarn; The weft winding method with different numbers of warp yarn layers in the reduced-layer area refers to the weft yarn winding method with different numbers of weft yarn layers in different areas at the same height of the fabric. The weft yarn is wound to the area with fewer weft yarn layers, and the weft yarn is wound out from the surface of the area, and the empty wound part is close to the outer surface layer.

6. The method for weaving a eccentric rotating body thickness gradient fabric according to claim 1, characterized in that: Each of the layer-linked braiding machines is respectively provided with a heald frame crossbeam and a plurality of frame bars, the top of each of the frame bars is installed on the heald frame crossbeam, and the frame bars are installed perpendicular to the heald frame crossbeam; Each of the frame strips is provided with a plurality of yarn hanging rings of different heights and arranged in a single row. The yarns on each of the frame strips are woven to form respective warp yarn rows. The warp yarns at different heights tied on the same frame strip are woven to form different layers of warp yarns inside and outside. During weaving, the heald frame crossbeam is distributed up and down according to the designed operation. Then, the warp yarns at the same height of different frame strips are pulled up in sequence from the innermost layer to the outermost layer to form a warp yarn layer. The interlacing openings are exposed between the warp yarn layers at different heights, and the weft yarn is wound. When winding the weft yarn, the weft yarn is passed through the interlacing opening. After winding a layer of warp yarns at the same height, the same operation is repeated to pull up the warp yarn layer at another height to wind the weft yarn, until the weft weaving from the inside to the outside is completed according to the design parameters.

7. Application of the weaving method according to any one of claims 1 to 6, characterized in that: The weaving method is used for weaving a fabric with continuously variable thickness in the axial direction and / or a fabric with variable thickness in the circumferential direction; The weaving method is used for manufacturing a large-size variable-thickness rotating body preform, wherein the fabric is a rotating body with a conical, cylindrical, truncated cone or other special-shaped outer contour, and the rotating body is a rotating cylinder with different outer contour axes and inner contour axes.

8. Application of the weaving method according to claim 7, characterized in that: The yarn of the fabric is quartz fiber, carbon fiber, silicon carbide fiber, silicon nitride fiber, glass fiber or aramid fiber.

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