Method for manufacturing a three-dimensional fabric with a profile

Abstract

The present application relates to the technical field of three-dimensional fabric forming, and particularly relates to a preparation method of a special-shaped three-dimensional fabric, comprising the following steps: drawing a U-shaped cross-section drawing, a covering area A is surrounded by a first area division line and an outer edge of the U-shaped cross-section drawing; a center splicing area C is surrounded by two second area division lines, the first area division line and a straight slot bottom edge, and a side splicing area B is surrounded by the first area division line and a straight slot side edge; the U-shaped cross-section drawing is cut and flattened along the two second area division lines to obtain a flattened cross-section drawing; the number, density and fineness of the warp yarns in the center splicing area C, the side splicing area B and the covering area A of the flattened cross-section drawing are designed; the weft yarn ply number and weft insertion structure in the center splicing area C and the side splicing area B of the flattened cross-section drawing are designed; an unfolded fabric is prepared, each weft yarn is pulled and tightened for arrangement, the unfolded fabric is bent and deformed, and a special-shaped three-dimensional fabric is obtained.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional fabric molding technology, and specifically to a method for preparing irregularly shaped three-dimensional fabrics. Background Technology

[0002] High-performance composite materials prepared using three-dimensional fabrics as reinforcement structures possess excellent integrity, strong designability, good weight reduction, and superior mechanical properties. They also exhibit functional characteristics such as wave transmission, wave absorption, high temperature resistance, and ablation resistance, and have been applied in various fields such as industrial products, aviation, and aerospace. Three-dimensional fabrics are formed by orderly interweaving continuous fiber bundles in space to create a unified structure. Their organizational structures include 2.5D, 2.5D weft-inserted, triaxial orthogonal, three-dimensional braiding, needle punching, and stitching structures. Three-dimensional fabrics typically feature fiber distribution designs based on the product's cross-section, including regular surfaces (such as rectangular, trapezoidal, or circular) and irregular surfaces. By systematically designing the fiber distribution in space, three-dimensional fabrics with different special structures can be prepared.

[0003] In the prior art, most three-dimensional fabrics are made into composite materials after being prepared and molded in a near-net-shape in one step. For example, Chinese patents CN103031651B and CN110258003B describe the preparation of a rotary shell product with a 2.5D structure; Chinese patent CN101899739B describes the preparation of a 2.5D curved plate fabric; and Chinese patent CN109914031B describes the preparation of a three-dimensional woven hourglass-shaped fabric. The above patents mostly use a one-step molding method to obtain three-dimensional fabrics, which is quite difficult to mold.

[0004] Therefore, in order to address the above problems, the present invention urgently needs to provide a method for preparing irregular three-dimensional fabrics. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a method for preparing irregular three-dimensional fabrics. The method involves dividing and unfolding the irregular three-dimensional fabric according to its cross-sectional shape, designing the distribution of warp and weft yarns, preparing the unfolded fabric based on the design parameters, and then performing bending deformation finishing based on the unfolded fabric. Finally, the overall preparation of the irregular three-dimensional fabric with U-shaped parts is achieved.

[0006] This invention provides a method for preparing an irregularly shaped three-dimensional fabric. The irregularly shaped three-dimensional fabric has a U-shaped section with a U-shaped cross-section, and a straight edge groove is provided at the top of the U-shaped section. The preparation method includes the following steps:

[0007] S1. Draw a U-shaped cross-sectional diagram based on the U-shaped cross-sectional shape of the U-shaped part. Offset a certain distance inward along the outer edge of the U-shaped cross-sectional diagram to obtain the first region dividing line. The first region dividing line and the outer edge of the U-shaped cross-sectional diagram form a covering region A. Connect the two inflection points of the first region dividing line to the corresponding endpoints of the bottom edge of the straight groove on the adjacent side to obtain the second region dividing line. The two second region dividing lines, the first region dividing line and the bottom edge of the straight groove form a central splicing region C. The second region dividing line, the first region dividing line and the side edge of the adjacent straight groove form a side splicing region B. Cut the U-shaped cross-sectional diagram along the two second region dividing lines. Flatten the covering region A and the side splicing region B to obtain a flattened cross-sectional diagram.

[0008] S2. Based on the area change rate of the central splicing area C, the side splicing area B, and the covering area A in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the preset parameters of the irregular three-dimensional fabric, the number of warp yarns, the warp yarn density, and the warp yarn fineness in the central splicing area C, the side splicing area B, and the covering area A in the flattened cross-section diagram are designed.

[0009] S3. Based on the height ratio of the side of the central splicing area C to the side of the adjacent side splicing area B in the flattened cross-section diagram, determine the ratio of the number of weft yarn layers in the central splicing area C and the side splicing area B. Based on the preset parameters of the irregular three-dimensional fabric and the ratio of the number of weft yarn layers in the central splicing area C and the side splicing area B, design the number of weft yarn plies and the weft insertion structure in the central splicing area C and the side splicing area B in the flattened cross-section diagram. In this case, a single weft yarn passes horizontally through one side splicing area B, the central splicing area C and the other side splicing area B in sequence.

[0010] S4. Based on the parameters obtained in S2 and S3, the unfolded fabric is prepared. The weft yarns are stretched and tightened to make the unfolded fabric bend and deform until the two sides of the central splicing area C are completely attached to one side of the corresponding side splicing area B, thus obtaining the irregular three-dimensional fabric.

[0011] Preferably, the preset parameters include the total warp density, total number of warp layers, total weft density, and total number of weft layers of the irregular three-dimensional fabric.

[0012] Preferably, in step S21, based on the area and area change rate of the central splicing area C, the side splicing area B, and the covering area A in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the total warp density of the irregular three-dimensional fabric, the number of warp yarns, the warp density, and the warp fineness in the central splicing area C, the side splicing area B, and the covering area A in the unfolded fabric are calculated, and additional yarn is added to the local areas with large area change rates.

[0013] S22, based on the total number of warp layers of the irregular three-dimensional fabric, the number of warp layers is designed according to the height correspondence between the central splicing area C and the side splicing area B in the U-shaped cross-section diagram and the flattened cross-section diagram; a stepped splicing area is designed on both sides of the central splicing area C and the inner side of the side splicing area B in the flattened cross-section diagram; the number of warp rows is designed according to the number of warp layers of the central splicing area C and the side splicing area B in the unfolded fabric and the angle of the splicing area, so as to obtain the warp arrangement of the central splicing area C and the side splicing area B in the flattened cross-section diagram.

[0014] Preferably, in step S31, based on the height ratio of the side of the central splicing area C to the side of the adjacent side splicing area B in the flattened cross-sectional view, the number of weft yarn layers in the central splicing area C and the side splicing area B is determined according to the total number of weft yarn layers of the irregular three-dimensional fabric.

[0015] S32, based on the number of weft yarn layers in the central splicing area C and the side splicing area B and the thickness of the irregular three-dimensional fabric, determine the weft yarn fineness and weft insertion structure in the central splicing area C and the side splicing area B.

[0016] Preferably, in step S41, an unfolded fabric is prepared based on the design parameters and dimensions of the flattened cross-section obtained in steps S2 and S3, and the three-dimensional fabric is bent and deformed with the axis of symmetry of the central splicing area C as a reference.

[0017] S42, during the bending deformation process, the weft yarns described in S3 are pulled and tightened to make each weft yarn straight in the central splicing area C and the side splicing area B, until the two sides of the central splicing area C are completely attached to one side of the corresponding side splicing area B, and the excess weft yarns are removed to complete the forming of the irregular three-dimensional fabric.

[0018] Preferably, the irregular three-dimensional fabric is one of the following: 2.5D structure, 2.5D weft-inserted structure, or other variable structure type 2.5D structure.

[0019] Preferably, the plane of symmetry of the central splicing area C coincides with the plane of symmetry of the U-shaped part of the irregular three-dimensional fabric.

[0020] Preferably, before S4, a pressure plate with a length greater than that of the irregular three-dimensional fabric is prepared, and multiple single-row needles are used to fix the unfolded fabric to the upper surface of the pressure plate along the thickness direction of the irregular three-dimensional fabric along the symmetrical plane of the central splicing area C, and the pressure plate is used as a fixed reference for multiple bending deformations.

[0021] Preferably, the distance between each row of needles is 20-40mm.

[0022] Preferably, in S2, the bottom of the central splicing area C and the arc portion of the covering area A with a large rate of change of area in the U-shaped cross-section and the flattened cross-section are treated with additional yarn, increasing the warp density by up to 20% and increasing the warp fineness to twice.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] After dividing and unfolding the irregular three-dimensional fabric according to its cross-sectional shape, the distribution of warp and weft yarns is designed. Based on the design parameters, the unfolded fabric is prepared, and then bending and deformation are performed on the unfolded fabric as a reference. Finally, the overall fabrication of the irregular three-dimensional fabric with U-shaped sections is achieved.

[0025] This invention provides a method for preparing irregularly shaped three-dimensional fabrics. The method involves dividing and unfolding the irregularly shaped three-dimensional fabric according to its cross-sectional shape. Based on the area changes of each part in the flattened and U-shaped cross-sectional diagrams, the quantity, density, and fineness of the warp and weft yarns are designed. The unfolded fabric is prepared based on the designed fabric parameters. Then, each weft yarn is pulled and tightened, thereby bending and deforming the unfolded fabric, ultimately achieving the overall preparation of the irregularly shaped three-dimensional fabric. Simultaneously, this invention also incorporates a stepped design in the splicing area, so that during the deformation process, the warp and weft yarns in the splicing area intersect to form a unified structure, eliminating splicing gaps generated during bending and deformation, and improving the overall integrity of the product. Compared to single-stage near-size weaving, this method for preparing irregularly shaped three-dimensional fabrics reduces the difficulty of the process by using two forming stages: weaving and deformation. Furthermore, the two-stage deformation forming reduces the fabric's dependence on special weaving equipment, allowing the production of complex-shaped products to be completed using conventional equipment. Attached Figure Description

[0026] Figure 1 This is a structural schematic diagram (sectional view) of the U-shaped portion of the irregular three-dimensional fabric described in the embodiment of the present invention;

[0027] Figure 2 This is a structural schematic diagram (sectional view) of the unfolded fabric according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of step S4 in the method for preparing irregular three-dimensional fabric according to an embodiment of the present invention;

[0029] Figure 4 The irregular three-dimensional fabric is obtained in step S4 of the method for preparing irregular three-dimensional fabric according to the embodiments of the present invention;

[0030] Figure 5 This is a production flow diagram of the method for preparing irregular three-dimensional fabrics according to an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the structure of a three-dimensional irregular fabric according to another embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram of the structure of a three-dimensional irregular fabric according to another embodiment of the present invention.

[0033] Wherein: 1. Covered area A; 2. Side splicing area B; 3. Central splicing area C; 4. First area dividing line; 5. Second area dividing line. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, a method for preparing an irregularly shaped three-dimensional fabric is disclosed. The irregularly shaped three-dimensional fabric has a U-shaped portion with a U-shaped cross-section. The top of the U-shaped portion is provided with a straight edge groove, wherein the axis of symmetry of the straight edge groove coincides with the axis of symmetry of the U-shaped portion. The method for preparing the U-shaped portion includes the following steps:

[0036] S1. Draw a U-shaped cross-sectional diagram based on the U-shaped cross-sectional shape of the U-shaped part. Offset the outer edge of the U-shaped cross-sectional diagram inward by a certain distance to obtain the first region dividing line 4. The first region dividing line 4, the outer edge of the U-shaped cross-sectional diagram, and the upper edge of the U-shaped cross-sectional diagram form a covering region A1. The first region dividing line 4 obtained by offsetting the outer edge of the U-shaped part includes straight line segments, arc segments, and straight line segments connected in sequence. Connect the two inflection points of the first region dividing line 4, i.e., the intersection points of each straight line segment and arc segment, to the bottom edge endpoint of the straight groove on the adjacent side. Two second region dividing lines 5 are obtained. The arc segments of the two second region dividing lines 5 and the first region dividing line 4, together with the bottom edge of the straight edge groove, form the central splicing area C3. The straight segments of each second region dividing line 5 and the first region dividing line 4, the side edge of the adjacent straight edge groove, and the upper edge of the U-shaped cross-section form the side splicing area B2. The U-shaped cross-section is cut along the two second region dividing lines 5 to separate the central splicing area C3 from the two side splicing areas B2. The covering area A1 and the side splicing areas B2 are flattened to obtain the flattened cross-section.

[0037] S2. Based on the area change rate of the central splicing area C3, the side splicing area B2 and the covering area A1 in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the preset parameters of the irregular three-dimensional fabric, the number of warp yarns, the warp yarn density and the warp yarn fineness in the central splicing area C3, the side splicing area B2 and the covering area A1 in the flattened cross-section diagram are designed.

[0038] First, relative to the U-shaped cross-sectional diagram, the area ratios of the central splicing area C3, the side splicing area B2, and the covering area A1 are calculated respectively. Based on the total warp density of the irregular three-dimensional fabric, the number of warp yarns in the central splicing area C3, the side splicing area B2, and the covering area A1 in the flattened cross-sectional diagram are calculated. At the same time, with the number of warp yarns remaining constant, during the flattening process, the rate of change of warp density in the same area is inversely proportional to the rate of change of area. Thus, the warp density of the central splicing area C3, the side splicing area B2, and the covering area A1 in the flattened cross-sectional diagram is calculated. Combined with the type of three-dimensional fabric, the warp fineness of the central splicing area C3, the side splicing area B2, and the covering area A1 in the flattened cross-sectional diagram is calculated.

[0039] S3, calculate the height ratio of the side of the central splicing area C3 to the side of the adjacent side splicing area B2 in the flattened cross-section diagram to obtain the weft yarn layer ratio of the central splicing area C3 and the side splicing area B2; based on the preset parameters of the irregular three-dimensional fabric and the weft yarn layer ratio of the central splicing area C3 and the side splicing area B2, obtain the weft yarn layer in the central splicing area C3 and the side splicing area B2 in the flattened cross-section diagram, and design the number of weft yarn plies and the weft insertion structure in the central splicing area C3 and the side splicing area B2 in the flattened cross-section diagram, wherein a single weft yarn passes horizontally through one side splicing area B2, the central splicing area C3 and the other side splicing area B2 in sequence;

[0040] S4. Based on the parameters obtained in S2 and S3, the unfolded fabric is prepared. The weft yarns are stretched and tightened to make the unfolded fabric bend and deform until the two sides of the central splicing area C3 are completely attached to one side of the corresponding side splicing area B2, thus obtaining the irregular three-dimensional fabric.

[0041] This invention provides a method for preparing irregularly shaped three-dimensional fabrics. The method involves dividing and unfolding the irregularly shaped three-dimensional fabric according to its cross-sectional shape. Based on the area changes of each part in the flattened and U-shaped cross-sectional diagrams, the quantity, density, and fineness of the warp and weft yarns are designed. The unfolded fabric is prepared based on the designed fabric parameters. Then, each weft yarn is pulled and tightened, thereby bending and deforming the unfolded fabric, ultimately achieving the overall preparation of the irregularly shaped three-dimensional fabric. Simultaneously, this invention also incorporates a stepped design in the splicing area, so that during the deformation process, the warp and weft yarns in the splicing area intersect to form a unified structure, eliminating splicing gaps generated during bending and deformation, and improving the overall integrity of the product. Compared to single-stage near-size weaving, this method for preparing irregularly shaped three-dimensional fabrics reduces the difficulty of the process by using two forming stages: weaving and deformation. Furthermore, the two-stage deformation forming reduces the fabric's dependence on special weaving equipment, allowing the production of complex-shaped products to be completed using conventional equipment.

[0042] In this embodiment, the preset parameters include the total warp density, total number of warp layers, total weft density, and total number of weft layers of the irregular three-dimensional fabric.

[0043] In this embodiment, S21, based on the area and area change rate of the central splicing area C3, the side splicing area B2 and the covering area A1 in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the total warp density of the irregular three-dimensional fabric, the number of warp yarns, the warp density and the warp fineness in the central splicing area C3, the side splicing area B2 and the covering area A1 in the unfolded fabric are calculated, and the local areas with large area change rates are treated by adding yarn.

[0044] S22, based on the total number of warp layers of the irregular three-dimensional fabric, the number of warp layers is designed according to the height correspondence between the central splicing area C3 and the side splicing area B2 in the U-shaped cross-sectional diagram and the flattened cross-sectional diagram; a stepped splicing area is designed on both sides of the central splicing area C3 and the inner side of the side splicing area B2 in the flattened cross-sectional diagram; the number of warp rows is designed according to the number of warp layers of the central splicing area C3 and the side splicing area B2 in the unfolded fabric and the angle of the splicing area, so as to obtain the warp arrangement of the central splicing area C3 and the side splicing area B2 in the flattened cross-sectional diagram.

[0045] In this embodiment, S31, based on the height ratio of the side of the central splicing area C3 to the side of the adjacent side splicing area B2 in the flattened cross-sectional view, the number of weft yarn layers in the central splicing area C3 and the side splicing area B2 is determined according to the total number of weft yarn layers of the irregular three-dimensional fabric.

[0046] S32, based on the number of weft yarn layers in the central splicing area C3 and the side splicing area B2 and the thickness of the irregular three-dimensional fabric, determine the weft yarn fineness and weft insertion structure in the central splicing area C3 and the side splicing area B2.

[0047] In this embodiment, S41, based on the design parameters and the dimensions of the flattened cross-section obtained in S2 and S3, an unfolded fabric is prepared, and the three-dimensional fabric is bent and deformed with the axis of symmetry of the central splicing area C3 as a reference.

[0048] S42, during the bending deformation process, the weft yarns mentioned in S3 are pulled and tightened to make each weft yarn straight in the central splicing area C3 and the side splicing area B2, until the two sides of the central splicing area C3 are completely attached to one side of the corresponding side splicing area B2, and the excess weft yarns are removed to complete the forming of the irregular three-dimensional fabric.

[0049] In this embodiment, the irregular three-dimensional fabric is one of the following: 2.5D structure, 2.5D weft-inserted structure, or other variable structure type 2.5D structure.

[0050] In this embodiment, the symmetry plane of the central splicing area C3 coincides with the symmetry plane of the U-shaped part of the irregular three-dimensional fabric.

[0051] In this embodiment, before S4, a pressure plate with a length greater than that of the irregular three-dimensional fabric is prepared. Multiple single-row needles are used to fix the unfolded fabric to the upper surface of the pressure plate along the thickness direction of the irregular three-dimensional fabric along the symmetrical plane of the central splicing area C3. The pressure plate is used as a fixed reference for multiple bending deformations.

[0052] In this embodiment, the distance between each row of needles is 20-40mm.

[0053] In this embodiment, the needle spacing of a single row of needles is 20-40mm.

[0054] In this embodiment, in S2, the bottom of the central splicing area C3 and the arc portion of the covering area A1 with a large area change rate in the U-shaped cross-section and the flattened cross-section are treated with additional yarn, increasing the warp density by up to 20% and the warp fineness by two times.

[0055] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, this invention provides an embodiment in which the irregular three-dimensional fabric is a glass fiber three-dimensional fabric with a U-shaped section in cross-section. The top of the U-shaped section has a straight edge groove. The thickness of the straight edge regions on both sides of the U-shaped section is 12-15 mm, the thickness of the arc region of the U-shaped section is 25-30 mm, the width of the U-shaped section (i.e., the width of the U-shaped cross-section) is 600 mm, and the width of the unfolded fabric (i.e., the width of the flattened cross-section) is 1200 mm. In the irregular three-dimensional fabric, the warp yarns are distributed parallel to the length direction of the irregular three-dimensional fabric, and the weft yarns are arranged parallel to the outer edge of the U-shaped cross-section. The preparation method includes the following steps:

[0056] S1. Draw a U-shaped cross-sectional diagram based on the U-shaped section's cross-sectional shape. Offset a certain distance inward along the outer edge of the U-shaped cross-sectional diagram to obtain the first region dividing line 4. The first region dividing line 4 and the outer edge of the U-shaped cross-sectional diagram enclose a covering region A1. Connect the two inflection points of the first region dividing line 4 to the corresponding endpoints of the bottom edge of the straight groove on the adjacent side to obtain the second region dividing line 5. The two second region dividing lines 5, the first region dividing line 4, and the bottom edge of the straight groove enclose a central splicing region C3. Each second region dividing line 5 and the first region dividing line 4... Dividing line 4 and the side edge of the adjacent straight groove form a side splicing area B2. Then, the first area dividing line 4 and the second area dividing line 5 divide the U-shaped cross-section into a central splicing area C3 that is approximately an isosceles trapezoid, two side splicing areas B2 that are right-angled trapezoids, and a strip-shaped covering area A1 that surrounds the two side splicing areas B2. The two sides of the central splicing area C3 are respectively attached to the hypotenuses of the two side splicing areas B2. The U-shaped cross-section is cut along the two second area dividing lines 5, and the covering area A1 and the side splicing areas B2 are flattened to obtain a flattened cross-section.

[0057] S2. Based on the area change rate of the central splicing area C3, the side splicing area B2 and the covering area A1 in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the preset parameters of the irregular three-dimensional fabric, the number of warp yarns, the warp yarn density and the warp yarn fineness in the central splicing area C3, the side splicing area B2 and the covering area A1 in the flattened cross-section diagram are designed.

[0058] S21. Based on the area and area change rate of the central splicing area C3, side splicing area B2, and covering area A1 in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the total warp density of the irregular three-dimensional fabric, the number of warp yarns, warp density, and warp fineness in the central splicing area C3, side splicing area B2, and covering area A1 of the unfolded fabric are calculated, and additional yarn is added to areas with large area change rates. As shown in Table 1, the irregular three-dimensional fabric is a 2.5D weft-inserted structure, and the area of ​​the central splicing area C3 is 6.1 cm². 2 The area of ​​the side-jointed region B2 is 4.5 cm². 2 The preset parameters are 10 warp layers, 11 weft layers, warp density of 10.0±0.2 threads / cm, and weft density of 4.0±0.1 threads / cm. The calculated warp fineness is 570tex. Therefore, 124 warp threads are needed in the central splicing area C3, and 90 warp threads are needed in the side splicing area B2. Local yarns are added to the middle position of the covering area A1, i.e., the arc deformation area and the bottom of the central splicing area C3, so that the local warp density is 12±0.2 threads / cm, and the local warp fineness is increased to 570tex*2 ply.

[0059] S22, based on the total number of warp layers of the irregularly shaped three-dimensional fabric, the number of warp layers is designed according to the height correspondence between the central splicing area C3 and the side splicing area B2 in the U-shaped cross-sectional diagram and the flattened cross-sectional diagram; stepped splicing areas are designed on both sides of the central splicing area C3 and the inner side of the side splicing area B2 in the flattened cross-sectional diagram; the number of warp rows is designed according to the number of warp layers of the central splicing area C3 and the side splicing area B2 in the unfolded fabric and the angle of the splicing area, thus obtaining the central splicing area C3 in the flattened cross-sectional diagram. The warp arrangement of the side splicing area B2 is shown in Table 1. When the side splicing area B2 is unfolded, it is a trapezoid with a length of 20mm and a height of 10mm. Therefore, in the unfolded fabric, the splicing area within the side splicing area B2 can be designed as 10 steps with a width of 2mm and a height of 9-10mm. When the center splicing area 3 is unfolded, it is a trapezoid with a width of 10mm and a height of 20mm. Therefore, in the unfolded fabric, the splicing area within the center splicing area 3 can be designed as 5 steps with a width of 2mm and a height of 7-20mm.

[0060] S3. Based on the height ratio of the side of the central splicing area C3 to the side of the adjacent side splicing area B2 in the flattened cross-section diagram, determine the weft yarn layer ratio of the central splicing area C3 and the side splicing area B2. Based on the preset parameters of the irregular three-dimensional fabric and the weft yarn layer ratio of the central splicing area C3 and the side splicing area B2, design the number of weft yarn plies and the weft insertion structure in the central splicing area C3 and the side splicing area B2 in the flattened cross-section diagram. In this case, a single weft yarn passes horizontally through one side splicing area B2, the central splicing area C3 and the other side splicing area B2 in sequence.

[0061] S31. Based on the height ratio of the side edge of the central splicing area C3 to the side edge of the adjacent side splicing area B2 in the flattened cross-sectional diagram, and based on the total number of weft yarn layers of the irregular three-dimensional fabric, determine the number of weft yarn layers in the central splicing area C3 and the side splicing area B2. In the flattened cross-sectional diagram, the height of the central splicing area C3 is 20mm, and the height of the side splicing area B2 is 10mm. Therefore, the number of weft yarn layers in the central splicing area C3 is calculated to be 20 layers, and the number of weft yarn layers in the side splicing area B2 is 10 layers. The ratio of the number of weft yarn layers in the two areas is 1:2.

[0062] S32, based on the number of weft yarn layers in the central splicing area C3 and the side splicing area B2, and the thickness of the irregular three-dimensional fabric, determine the weft yarn fineness and weft insertion structure within the central splicing area C3 and the side splicing area B2. The ratio of the number of weft insertion layers in the central splicing area C3 to the side splicing area B2 is 1:2. Therefore, based on the three-dimensional fabric size parameters and the number of warp and weft yarn layers, calculate that the fineness of each weft yarn layer in the side splicing area B2 is 570*2tex, and the fineness of each weft yarn layer in the central splicing area C3 is 570tex. The weft insertion structure involves using 570tex fibers to repeatedly wrap around the weft yarn in both areas, with the first 570tex weft yarn sequentially introduced into the left side splicing area. The first layer of area B2, the first layer of the central splicing area C3, and the first layer of the right side splicing area B2 are folded back. The second 570tex weft yarn is then sequentially introduced into the first layer of the right side splicing area B2, the second layer of the central splicing area C3, and the first layer of the left side splicing area B2. The third 570tex weft yarn is then sequentially introduced into the second layer of the left side splicing area B2, the third layer of the central splicing area C3, and the second layer of the right side splicing area B2. After folding back, the fourth 570tex weft yarn is then sequentially introduced into the second layer of the right side splicing area B2, the fourth layer of the central splicing area C3, and the second layer of the left side splicing area B2. The above steps are repeated to complete the weft insertion of all weft yarns. Figure 2 , Figure 3 , Figure 4 As shown;

[0063] S4. Based on the parameters obtained in S2 and S3, prepare the unfolded fabric, pull and tighten each weft yarn to make the unfolded fabric bend and deform until the two sides of the central splicing area C3 are completely attached to one side of the corresponding side splicing area B2 to obtain the irregular three-dimensional fabric.

[0064] S41, based on the design parameters and dimensions of the flattened cross-section obtained in S2 and S3, prepare the unfolded fabric. Using the axis of symmetry of the central splicing area C3 as a reference, bend and deform the three-dimensional fabric. First, prepare a pressure plate with a length greater than that of the irregular three-dimensional fabric. Use multiple single-row needles along the plane of symmetry of the central splicing area C3 and along the thickness direction of the irregular three-dimensional fabric to fix the unfolded fabric to the upper surface of the pressure plate. The needle spacing is 20-40mm. Use the pressure plate as a fixed reference to perform multiple bending and deformation operations.

[0065] S42, during the bending deformation process, the weft yarns described in S3 are pulled and tightened to ensure that each weft yarn is straightly distributed within the central splicing area C3 and the side splicing area B2, until both sides of the central splicing area C3 are completely aligned with one side of the corresponding side splicing area B2. Excess weft yarns are removed to complete the forming of the irregular three-dimensional fabric. During the finishing process, the folded ends of the weft yarns on both sides of the fabric are pulled outward along the fabric profile direction, so that the weft yarns in the side splicing area B2-central splicing area C3-side splicing area B2 are all straightly arranged during multiple deformation processes. With repeated bending and finishing, the stepped splicing area in the side splicing area B2 and the stepped splicing areas on both sides of the central splicing area C3 are in complete contact and compression, and the warp and weft yarns in the splicing area combine to complete the homogeneous bending deformation of the fabric.

[0066] Table 1. Parameters of "U" Shaped Fabrics

[0067]

[0068] like Figure 6 As shown, the present invention also provides an embodiment in which the three-dimensional fabric includes two legs arranged at an angle, the outer sides of the connection between the first and second legs are smoothly connected, and the inner sides are connected by multiple straight edges. In this embodiment, the connection between the first and second legs forms a U-shaped portion with a certain included angle between the two straight edge areas. The preparation process includes the following steps:

[0069] S1, draw according to the U-shaped cross-sectional shape of the U-shaped part as follows: Figure 6As shown in the cross-sectional view, offset inward by a certain distance along the outer edge of the U-shaped cross-section to obtain the first region dividing line 4. The first region dividing line 4 and the outer edge of the U-shaped cross-section form a covering region A1. Connect the two inflection points of the first region dividing line 4 to the corresponding endpoints of the bottom edge of the straight groove on the adjacent side to obtain the second region dividing line 5. The two second region dividing lines 5, the first region dividing line 4 and the bottom edge of the straight groove form a central splicing region C3. The two second region dividing lines 5, the first region dividing line 4 and the side edge of the adjacent straight groove form a side splicing region B2. Cut the U-shaped cross-section along the two second region dividing lines 5, and flatten the covering region A1 and the side splicing region B2 to obtain a flattened cross-section.

[0070] S2. Based on the area change rate of the central splicing area C3, the side splicing area B2 and the covering area A1 in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the preset parameters of the irregular three-dimensional fabric, the number of warp yarns, the warp yarn density and the warp yarn fineness in the central splicing area C3, the side splicing area B2 and the covering area A1 in the flattened cross-section diagram are designed.

[0071] S3. Based on the height ratio of the side of the central splicing area C3 to the side of the adjacent side splicing area B2 in the flattened cross-section diagram, determine the weft yarn layer ratio of the central splicing area C3 and the side splicing area B2. Based on the preset parameters of the irregular three-dimensional fabric and the weft yarn layer ratio of the central splicing area C3 and the side splicing area B2, design the number of weft yarn plies and the weft insertion structure in the central splicing area C3 and the side splicing area B2 in the flattened cross-section diagram. In this case, a single weft yarn passes horizontally through one side splicing area B2, the central splicing area C3 and the other side splicing area B2 in sequence.

[0072] S4. Based on the parameters obtained in S2 and S3, the unfolded fabric is prepared. The weft yarns are stretched and tightened to make the unfolded fabric bend and deform until the two sides of the central splicing area C3 are completely attached to one side of the corresponding side splicing area B2, thus obtaining the irregular three-dimensional fabric.

[0073] like Figure 7 As shown, the present invention also provides an embodiment in which the three-dimensional fabric includes spaced-apart flat structures and raised structures, the raised structures being considered as... Figure 1 A rectangular section is joined within the straight-edge groove of the structure shown. The fabrication process includes the following steps:

[0074] S1, draw according to the U-shaped cross-sectional shape of the U-shaped part as follows: Figure 7As shown in the cross-sectional view, offset inward by a certain distance along the outer edge of the U-shaped cross-section to obtain the first region dividing line 4. The first region dividing line 4 and the outer edge of the U-shaped cross-section form a covering region A1. Connect the two inflection points of the first region dividing line 4 to the corresponding endpoints of the bottom edge of the straight groove on the adjacent side to obtain the second region dividing line 5. The two second region dividing lines 5, the first region dividing line 4 and the bottom edge of the straight groove form a central splicing region C3. The two second region dividing lines 5, the first region dividing line 4 and the side edge of the adjacent straight groove form a side splicing region B2. Cut the U-shaped cross-section along the two second region dividing lines 5, and flatten the covering region A1 and the side splicing region B2 to obtain a flattened cross-section.

[0075] S2. Based on the area change rate of the central splicing area C3, the side splicing area B2 and the covering area A1 in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the preset parameters of the irregular three-dimensional fabric, the number of warp yarns, the warp yarn density and the warp yarn fineness in the central splicing area C3, the side splicing area B2 and the covering area A1 in the flattened cross-section diagram are designed.

[0076] S3. Based on the height ratio of the side of the central splicing area C3 to the side of the adjacent side splicing area B2 in the flattened cross-section diagram, determine the weft yarn layer ratio of the central splicing area C3 and the side splicing area B2. Based on the preset parameters of the irregular three-dimensional fabric and the weft yarn layer ratio of the central splicing area C3 and the side splicing area B2, design the number of weft yarn plies and the weft insertion structure in the central splicing area C3 and the side splicing area B2 in the flattened cross-section diagram. In this case, a single weft yarn passes horizontally through one side splicing area B2, the central splicing area C3 and the other side splicing area B2 in sequence.

[0077] S4. Based on the parameters obtained in S2 and S3, the unfolded fabric is prepared. The weft yarns are stretched and tightened to make the unfolded fabric bend and deform until the two sides of the central splicing area C3 are completely attached to one side of the corresponding side splicing area B2, thus obtaining the irregular three-dimensional fabric.

[0078] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing irregularly shaped three-dimensional fabric, characterized in that: The irregularly shaped three-dimensional fabric has a U-shaped section with a U-shaped cross-section, and a straight edge groove is provided at the top of the U-shaped section. The preparation method includes the following steps: S1. Draw a U-shaped cross-section diagram according to the U-shaped cross-section shape of the U-shaped part. Offset a certain distance inward along the outer edge of the U-shaped cross-section diagram to obtain the first region dividing line (4). The first region dividing line (4) and the outer edge of the U-shaped cross-section diagram form a covering region A (1). Connect the two inflection points of the first region dividing line (4) to the corresponding endpoints of the bottom edge of the straight edge groove on the adjacent side to obtain the second region dividing line (5). The two second region dividing lines (5), the first region dividing line (4) and the bottom edge of the straight edge groove form a central splicing region C (3). The second region dividing lines (5), the first region dividing line (4) and the side edge of the adjacent straight edge groove form a side splicing region B (2). Cut the U-shaped cross-section diagram along the two second region dividing lines (5). Flatten the covering region A (1) and the side splicing region B (2) to obtain a flattened cross-section diagram. S2, relative to the U-shaped cross-section diagram, calculate the area change rate of the central splicing area C(3), the side splicing area B(2) and the covering area A(1) in the flattened cross-section diagram. Based on the preset parameters and area change rate of the irregular three-dimensional fabric, design the number of warp yarns, warp yarn density and warp yarn fineness in the central splicing area C(3), the side splicing area B(2) and the covering area A(1) in the flattened cross-section diagram. S3. Based on the height ratio of the side of the central splicing area C(3) to the side of the adjacent side splicing area B(2) in the flattened cross section diagram, determine the ratio of the number of weft yarn layers in the central splicing area C(3) and the side splicing area B(2); based on the preset parameters of the irregular three-dimensional fabric and the ratio of the number of weft yarn layers in the central splicing area C(3) and the side splicing area B(2), design the number of weft yarn ply and the weft insertion structure in the central splicing area C(3) and the side splicing area B(2) in the flattened cross section diagram, wherein a single weft yarn passes horizontally through one side splicing area B(2), the central splicing area C(3) and the other side splicing area B(2) in sequence; S4. Based on the parameters obtained in S2 and S3, the unfolded fabric is prepared. The weft yarns are pulled and tightened to make the unfolded fabric bend and deform until the two sides of the central splicing area C(3) are completely attached to one side of the corresponding side splicing area B(2) to obtain the irregular three-dimensional fabric.

2. The method for preparing irregular three-dimensional fabric according to claim 1, characterized in that: The preset parameters include the total warp density, total number of warp layers, total weft density, and total number of weft layers of the irregular three-dimensional fabric.

3. The method for preparing irregular three-dimensional fabric according to claim 2, characterized in that: S21. Based on the area and area change rate of the central splicing area C(3), side splicing area B(2) and covering area A(1) in the U-shaped cross-section diagram and the flattened cross-section diagram, and based on the total warp density of the irregular three-dimensional fabric, the number of warp yarns, warp density and warp fineness in the central splicing area C(3), side splicing area B(2) and covering area A(1) in the unfolded fabric are calculated, and the local area with large area change rate is treated by adding yarn. S22, based on the total number of warp layers of the irregular three-dimensional fabric, the number of warp layers is designed according to the height correspondence between the central splicing area C(3) and the side splicing area B(2) in the U-shaped cross-section diagram and the flattened cross-section diagram; a stepped splicing area is designed on both sides of the central splicing area C(3) and the inner side of the side splicing area B(2) in the flattened cross-section diagram; the number of warp rows is designed according to the number of warp layers of the central splicing area C(3) and the side splicing area B(2) in the unfolded fabric and the angle of the splicing area, so as to obtain the warp arrangement of the central splicing area C(3) and the side splicing area B(2) in the flattened cross-section diagram.

4. The method for preparing irregular three-dimensional fabric according to claim 3, characterized in that: S31. Based on the height ratio of the side of the central splicing area C(3) and the side of the adjacent side splicing area B(2) in the flattened cross section diagram, the number of weft yarn layers in the central splicing area C(3) and the side splicing area B(2) is determined according to the total number of weft yarn layers of the irregular three-dimensional fabric. S32, based on the number of weft yarn layers and the thickness of the irregular three-dimensional fabric in the central splicing area C(3) and the side splicing area B(2), determine the weft yarn fineness and weft insertion structure in the central splicing area C(3) and the side splicing area B(2).

5. The method for preparing irregular three-dimensional fabric according to claim 4, characterized in that: S41, based on the design parameters and the dimensions of the flattened cross section obtained in S2 and S3, the unfolded fabric is prepared, and the three-dimensional fabric is bent and deformed with the axis of symmetry of the central splicing area C(3) as the reference. S42, during the bending deformation process, the weft yarns described in S3 are pulled and tightened so that each weft yarn is straightly distributed in the central splicing area C(3) and the side splicing area B(2) until the two sides of the central splicing area C(3) are completely attached to one side of the corresponding side splicing area B(2), and the excess weft yarns are removed to complete the forming of the irregular three-dimensional fabric.

6. The method for preparing irregular three-dimensional fabric according to claim 5, characterized in that: The irregular three-dimensional fabric is one of the following: 2.5D structure, 2.5D weft-inserted structure, or other variable structure 2.5D structure.

7. The method for preparing irregular three-dimensional fabric according to claim 6, characterized in that: The symmetry plane of the central splicing area C(3) coincides with the symmetry plane of the U-shaped part of the irregular three-dimensional fabric.

8. The method for preparing irregular three-dimensional fabric according to claim 7, characterized in that: Before S4, a pressure plate with a length greater than that of the irregular three-dimensional fabric is prepared. Multiple single-row needles are used to fix the unfolded fabric on the upper surface of the pressure plate along the thickness direction of the irregular three-dimensional fabric along the symmetry plane of the central splicing area C(3). The pressure plate is used as a fixed reference for multiple bending deformations.

9. The method for preparing irregular three-dimensional fabric according to claim 8, characterized in that: The distance between each row of needles is 20-40mm.

10. The method for preparing irregular three-dimensional fabric according to claim 9, characterized in that: In S2, the bottom of the central splicing area C(3) with a large rate of change of area in the U-shaped cross-section and the arc part of the covering area A(1) are treated with additional yarn, increasing the warp density by up to 20% and increasing the warp fineness to twice.

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