A high-load-bearing needle-punched fabric based on short fiber stripping and its preparation method

Abstract

The present application relates to a kind of high bearing needle-punched fabric based on short fiber stripping and its preparation method, comprising the following steps, S1, preparation raw material: S2, layer needle punching: S3, electric push stripping: using electric pusher to have been needle-punched unit layer top carbon fiber web tire removal, only carbon fiber spread cloth bottom unit layer is obtained;S4, cycle needle punching: continue to lay the next unit layer in the fabric thickness direction of bottom unit layer, carbon fiber web tire in it is placed angle and the last unit layer keep consistent, according to the actual thickness of layer lifting the needle punching height of stripping net plate, the needle punching track in horizontal plane keeps unchanged to ensure that needle-punching robot carries out in situ needle punching, after needle punching, continue to use electric pusher to remove carbon fiber web tire on unit layer top;S4 is recycled until the needle-punched forming of entire fabric target thickness is completed.The fabric structure used in the present application has no web tire layer, and the bulk density and load capacity of the fabric are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber needle-punched preforms and preparation thereof, and in particular relates to a high-load-bearing needle-punched fabric based on short fiber stripping and a preparation method thereof. Background Art

[0002] The production of three-dimensional needle-punched fabrics and their composite materials has the advantages of a high degree of automation and a simple molding process. Compared with traditional laminates, their interlayer and in-plane mechanical properties have been greatly improved, and they have now been widely used in aerospace, rail transportation and other fields.

[0003] In recent years, researchers have proposed various types of needle-punched fabric structures, including mesh / mesh laminated needle-punched structure, mesh / woven cloth laminated needle-punched structure and mesh / half-cut cloth laminated needle-punched structure. The above-mentioned fabric structures all contain a web layer or a half-cut fabric layer, such as the similar fabric described in the invention patent with patent number CN202210583334.0, publication number CN115179609A, and patent name "A lightweight drainage and heat-insulating composite material and its preparation method". This fabric with a web layer has a low volume fraction, and the non-load-bearing web layer will greatly reduce the mechanical properties of the fabric. At the same time, fabrics containing half-cut fabric layers in the fabric layup structure, such as the similar fabrics described in the invention patent number CN202110723618.0, publication number CN113638134A, and patent name "A high-volume-fraction, high-performance needle-punched preform and its preparation method", still have discontinuous short fibers in their surface. If the residual short fibers are not cleaned, the overall in-plane tensile strength of the fabric will be reduced. Existing needle-punched fabric structures are difficult to meet the load-bearing requirements of key components of hypersonic aircraft. Therefore, it is necessary to explore a new type of high-volume-fraction, high-load-bearing needle-punched fabric structure and its preparation method. Summary of the Invention

[0004] The present invention provides a high-load-bearing needle-punched fabric based on short fiber stripping and a preparation method thereof to solve the technical problems existing in the known technology. The fabric structure has no mesh layer, and the bulk density and load-bearing capacity of the fabric are improved.

[0005] The present invention includes the following technical solutions: A method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping, comprising the following steps:

[0006] S1. Prepare raw materials: Precisely cut the mesh according to the pre-designed half-cut trajectory to form a carbon fiber mesh and a carbon fiber spread cloth of appropriate sizes; the carbon fiber mesh is processed into a half-cut mesh;

[0007] S2. Layer Needling: Several layers of carbon fiber spread fabric and a layer of carbon fiber mat are stacked and laid in sequence from bottom to top to form a unit layer, with the carbon fiber mat on top of the unit layer; the unit layer is needled using a needle punching robot according to a pre-programmed needle punching program;

[0008] S3, electric stripping: Use electric clippers to remove the carbon fiber web on the top of the needle-punched unit layer to obtain the bottom unit layer of only the carbon fiber stretched cloth;

[0009] S4, cyclic needling: continue to lay down the next unit layer in the direction of the fabric thickness of the bottom unit layer, and the placement angle of the carbon fiber mesh is consistent with that of the previous unit layer. Raise the needling height of the stripping plate according to the actual thickness of the layer. The needling trajectory in the horizontal plane remains unchanged to ensure that the needling robot can perform in-situ needling. After the needling is completed, continue to use the electric clipper to remove the carbon fiber mesh on the top of the unit layer; repeat S4 until the needling forming of the entire fabric target thickness is completed.

[0010] Furthermore, the S1 includes S1-1 designing a half-cut mesh and S1-2 cutting the carbon fiber mesh and the carbon fiber spread cloth; S1-1 uses AUTOCAD software to perform parameterized design of the half-cut trajectory of the carbon fiber mesh, and half-cutting the mesh refers to cutting the carbon fiber mesh at equal intervals in the horizontal or vertical direction, and the trajectories of the previous row and the next row or the previous column and the next column are staggered, and the staggered distance is half of the spacing between the two incisions, generating an ordered arrangement set network with several fixed-value incisions; S1-2 transfers the half-cut cutting trajectory file generated by the AUTOCAD software and the cutting trajectory file of the appropriate size required for the raw material to the CNC cutting machine supporting software on the PC side, generates a file that can execute the cutting task, and then uses a USB flash drive to download the file from the PC side to the CNC cutting machine, and finally lays the raw material rolls of the carbon fiber mesh and the carbon fiber spread cloth horizontally on the CNC cutting machine, starts the machine, and performs precise cutting of the raw materials to form carbon fiber mesh and carbon fiber spread cloth of appropriate sizes in turn.

[0011] Furthermore, the half-cut trajectory parameters in S1-1 include the incision length L and the incision spacing b. The incision length is 15 to 35 mm, and the spacing between two adjacent incisions is 10 to 30 mm.

[0012] Furthermore, the CNC cutting machine in S1-2 is a French Gerber Z1 series digital cutting machine.

[0013] Furthermore, the appropriate sizes of the carbon fiber web and the carbon fiber spreader fabric in S1-2 are determined according to experimental requirements.

[0014] Furthermore, the surface density of the carbon fiber mesh in S1-2 is 50-60 g / m2; the structure of the carbon fiber spread fabric is plain weave, and the specifications of the spread fabric are a grid width of 8-9 mm and a surface density of 200-205 g / m2. 2 Or the grid width is 16-17mm, the surface density is 100-105g / m 2 Or the grid width is 20-21mm, the surface density is 80-85g / m 2 .

[0015] Furthermore, when laying and cutting the raw material roll in S1-2, it is necessary to ensure that the warp or weft direction of the web and the stretched fabric is parallel to the X-axis or Y-axis of the horizontal coordinate system of the cutting table to ensure the accuracy of cutting.

[0016] Furthermore, the S2 includes S2-1 writing a needling program, S2-2 laying the needling raw materials and S2-3 needling; S2-1 uses the actual layer thickness value of the unit layer as the raised needling height of the robot end effector; and the number of needles on the needle board, the adopted needling density value, the needling depth value and the needling starting point posture information are input into the needling robot programming software to generate a programmable needling execution program; S2-2 stacks the carbon fiber expanded cloth and carbon fiber mesh tire cut in S1 into unit layers according to the designed laying sequence. When laying, it is necessary to ensure that the length and width direction of the raw materials and the length and width direction of the needling workbench are parallel to each other to ensure the consistency of the actual needling trajectory and the designed trajectory; S2-3 downloads the needling program generated in S2-1 to the robot teach pendant, adjusts and calibrates the needling robot, and continuously needles the unit layer according to the written needling program.

[0017] Furthermore, the number of needles on the needle plate in S2-1 is 47; the needle density can be selected from 10 to 30 needles / cm 2 ; The acupuncture depth can be selected from 10 to 20 mm.

[0018] Furthermore, one unit layer in S2-2 may be composed of 3 to 5 layers of carbon fiber stretched fabrics and 1 layer of carbon fiber web.

[0019] Furthermore, the needle models used in S2-3 can be selected from the thin needle 15×18×40×3C222JZ13801, the medium needle 15×18×36×3C333 D24101, and the thick needle 14×16×36×3C333JZ01301.

[0020] Furthermore, the continuous needling in S2-3 adopts a needling method of first needling and then pressing. The advantage of this is that the stripping plate contacts the fabric surface first, giving the fabric a pre-pressure, compacting the layered fabric, which is more conducive to the intervention of the needle to drive the short fibers of the mesh to achieve interlayer connection, while improving the molding effect.

[0021] Furthermore, the electric clipper in S3 comprises a combination of a static blade at the bottom and a dynamic blade at the top. During stripping, the blade is positioned on the bottom surface of the upper right corner of the carbon fiber web, cutting approximately 20 degrees from the web's length. The blade moves in an "S" shape, advancing the clipper to shear the Z-direction needle-punched fiber bundles. During stripping, the portion of the carbon fiber web to be stripped is held, supporting the web to minimize the pulling out of the Z-direction needle-punched fiber bundles, thereby increasing the residual strength between layers.

[0022] Furthermore, the cutter head moves in an "S" shape from the bottom surface of the upper right corner of the carbon fiber mesh to the lower left in an "S" shape to the left side, and then moves to the lower right to the right side as a cycle, and repeats the above process until the entire carbon fiber mesh is removed.

[0023] Furthermore, before each needling in S4, the actual thickness value of the ply needs to be input into the needling robot programming software to generate a new programmable needling execution program, which is downloaded to the robot teaching pendant, and the needling robot is started to run the program to continuously needle the fabric.

[0024] A high-load-bearing needle-punched fabric based on short fiber stripping is made using the above-mentioned preparation method. The fabric comprises several layers of carbon fiber spread cloth and several needle-punched fiber bundles vertically inserted into the layers.

[0025] Compared with the prior art, the present invention has the following advantages and positive effects:

[0026] 1. The present invention proposes a short-fiber-stripped needle-punched fabric structure. Under the premise of constant fabric thickness, a widened fabric is used to replace the stripped mat layer in the structure, thereby improving the fabric's volume density and load-bearing capacity. There is no mat layer between the unit layers of the fabric structure, and the same material makes the interlayer connection closer and tighter, thereby improving the interlayer peeling strength of the fabric.

[0027] 2. The present invention uses an electric clipper to peel the carbon fiber mesh layer, which improves the peeling efficiency and can leave more needle-punched fiber bundles between layers, effectively improving the interlayer peeling strength of the fabric and the type I interlayer fracture toughness of the composite material.

[0028] 3. When the present invention uses an electric clipper for stripping, the blade of the electric clipper cuts in at a certain angle and moves in an "S" shape to cut the needle-punched fiber bundle, thereby quickly and efficiently removing the carbon fiber web and greatly reducing the loss of the needle-punched fiber bundle.

[0029] 4. The present invention adopts half-cutting of the web to further release the entanglement and restraint force between the short fibers in the web surface, which is conducive to the needle bringing more short fibers into the interlayer, thereby improving the interlayer peeling strength of the fabric and the type I interlayer fracture toughness of the composite material.

[0030] 5. The present invention adopts in-situ needling, which reduces the damage of the needle to the fabric and improves the in-plane tensile properties of the fabric and its composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the high-load-bearing needle-punched fabric based on short fiber stripping of the present invention;

[0032] Figure 2 Schematic diagram of the fabric preparation process of the present invention;

[0033] Figure 3 Schematic diagram of the short fiber stripping path of the present invention;

[0034] Figure 4 Schematic diagram of the interlayer peeling and in-plane stretching sequence of the fabric;

[0035] In the figure, 1-carbon fiber stretched cloth; 2-needle-punched fiber bundle; 3-carbon fiber mesh; 4-needle plate; 5-electric clipper; 6-short fiber stripping starting point; 7-incision length; 8-incision spacing. DETAILED DESCRIPTION

[0036] In order to further disclose the content, features and effects of the present invention, the following examples are given and described in detail with reference to the accompanying drawings.

[0037] See attached Figure 1-4 , a method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping, comprising the following steps:

[0038] S1. Prepare raw materials: Precisely cut the carbon fiber mesh 3 according to the pre-designed half-cut trajectory to form a carbon fiber mesh 3 and a carbon fiber spread fabric 1 of appropriate sizes in sequence; process the carbon fiber mesh 3 into a half-cut mesh; S1 includes S1-1 designing the half-cut mesh and S1-2 cutting the carbon fiber mesh 3 and the carbon fiber spread fabric 1:

[0039] S1-1 uses AUTOCAD software to parametrically design the half-cut trajectory of the carbon fiber mesh 3. Half-cutting the mesh refers to cutting the carbon fiber mesh 3 at equal intervals in the horizontal or vertical direction, and the trajectories of the previous row and the next row or the previous column and the next column are staggered with each other, and the staggered distance is half of the spacing 8 between the two incisions, generating an ordered arrangement set network with several fixed-value incisions; the half-cut trajectory parameters in S1-1 include the incision length 7 and the incision spacing 8, the incision length 7 is 15 to 35 mm, and the spacing 8 between two adjacent incisions is 10 to 30 mm.

[0040] S1-2 transfers the half-cutting trajectory file generated by the AUTOCAD software and the cutting trajectory file of the appropriate size required for the raw material to the CNC cutting machine supporting software on the PC side, generates a file that can execute the cutting task, and then uses a USB flash drive to download the file from the PC side to the CNC cutting machine. Finally, the raw material rolls of the carbon fiber mesh 3 and the carbon fiber spread cloth 1 are horizontally laid on the CNC cutting machine respectively, and the machine is started to perform precise cutting of the raw materials to form the carbon fiber mesh 3 and the carbon fiber spread cloth 1 of appropriate sizes in turn.

[0041] The CNC cutting machine in S1-2 is a French Gerber Z1 series digital cutting machine. The appropriate size of the carbon fiber mesh 3 and the carbon fiber spread fabric 1 in S1-2 is determined according to the experimental requirements. The surface density of the carbon fiber mesh 3 in S1-2 is 50-60g / m2; the structure of the carbon fiber spread fabric 1 is plain weave, the spread fabric specifications are 8-9mm in width, and the surface density is 200-205g / m 2 Or the grid width is 16-17mm, the surface density is 100-105g / m 2 Or the grid width is 20-21mm, the surface density is 80-85g / m 2 When laying and cutting the raw material roll in S1-2, it is necessary to ensure that the warp or weft direction of the web and the stretched fabric is parallel to the X axis or Y axis of the horizontal coordinate system of the cutting table to ensure the accuracy of cutting.

[0042] S2. Needle punching: Several layers of carbon fiber stretched fabric 1 and a layer of carbon fiber web 3 are stacked and laid in sequence from bottom to top to form a unit layer, with the carbon fiber web 3 located on top of the unit layer; a needle punching robot is used to needle punch the unit layer according to a pre-programmed needle punching program; S2 includes S2-1 programming the needle punching program, S2-2 laying the needle punching raw materials, and S2-3 needle punching:

[0043] S2-1 uses the actual thickness of the unit layer as the height of the raised needling of the robot end effector; and inputs the number of needles on the needle plate 4, the adopted needling density value, the needling depth value and the needling starting point posture information into the needling robot programming software to generate a programmable needling execution program; the number of needles on the needle plate 4 in S2-1 is 47; the needling density can be selected from 10 to 30 needles / cm 2 ; The acupuncture depth can be selected from 10 to 20 mm.

[0044] S2-2 stacks the cut carbon fiber spread cloth 1 and carbon fiber mesh 3 in S1 into unit layers according to the designed laying order. When laying, it is necessary to ensure that the length and width directions of the raw materials and the length and width directions of the needling workbench are parallel to each other to ensure the consistency between the actual needling trajectory and the designed trajectory; one unit layer in the S2-2 can be selected to be composed of 3 to 5 layers of carbon fiber spread cloth 1 and 1 layer of carbon fiber mesh 3.

[0045] S2-3 downloads the needling program generated in S2-1 to the robot teach pendant, adjusts and calibrates the needling robot, and continuously needles the unit layer according to the programmed needling program. The needle models used in S2-3 can be selected from the fine needle 15×18×40×3C222 JZ13801, the medium needle 15×18×36×3C333D24101, and the coarse needle 14×16×36×3C333 JZ01301. The continuous needling in S2-3 adopts a needling method of first needling and then pressing. This has the advantage that the stripping plate contacts the fabric surface first, applying pre-pressure to the fabric and compacting the layered fabric. This is more conducive to the intervention of the needles to drive the short fibers of the mesh to achieve interlayer connection, while also improving the molding effect.

[0046] S3, electric push stripping: Use electric clippers 5 to remove the carbon fiber mesh 3 on the top of the completed unit layer, obtaining a bottom unit layer consisting of only the carbon fiber widened cloth 1; the blade of the electric clippers 5 in S3 is a combination of a bottom static blade and a top dynamic blade. During stripping, the blade is placed on the bottom surface of the upper right corner of the carbon fiber mesh 3, which is also the starting point 6 for short fiber stripping, so that the blade cuts in at approximately 20° relative to the length direction of the carbon fiber mesh 3; the blade moves in an "S" shape, and the electric clippers 5 advance to cut the Z-direction needle-punched fiber bundle 2. During stripping, the stripped portion of the carbon fiber mesh 3 is held, and the mesh is supported during stripping to minimize the pulling out of the Z-direction needle-punched fiber bundle 2, thereby improving the residual strength between layers.

[0047] The electric clipper 5 in S3 is a rechargeable model, a Chigo ZG-F838 series, with a 3.7V motor and a titanium alloy ceramic blade. The blade moves in an "S" shape, specifically from the bottom surface of the upper right corner of the carbon fiber mesh 3 to the lower left, then to the left side, and then to the lower right and right side. This process is repeated until the entire carbon fiber mesh 3 is removed.

[0048] S4, cyclic needling: Continue laying down the next unit layer in the direction of the fabric thickness of the bottom unit layer, with the carbon fiber mesh 3 placed at the same angle as the previous unit layer. Raise the needling height of the stripping plate according to the actual thickness of the layer, and keep the needling trajectory in the horizontal plane unchanged to ensure that the needling robot can perform in-situ needling. After the needling is completed, continue to use the electric clipper 5 to remove the carbon fiber mesh 3 on the top of the unit layer; repeat S4 until the entire fabric is needling to the target thickness. Before each needling in S4, the needling height value needs to be input into the needling robot programming software to generate a new programmable needling execution program. This program is downloaded to the robot teach pendant, and the needling robot is started to run the program to continuously needle the fabric.

[0049] The present invention also includes a high-load-bearing needle-punched fabric based on short fiber stripping, which is made using the above-mentioned preparation method. The fabric includes several layers of carbon fiber spread fabric 1 and several needle-punched fiber bundles 2 vertically inserted into the layers.

[0050] Example 1:

[0051] A high-load-bearing needle-punched fabric based on short fiber stripping has only carbon fiber widened cloth in the surface and no carbon fiber mesh. The mesh used in the needle-punching of the fabric layer is a half-cut mesh with incisions.

[0052] Needle punching process: After each unit layer is needled, the half-cut mesh layer on the surface is peeled off, and then the next unit layer is laid and peeled off by needling.

[0053] Material parameters: The surface density of the carbon fiber widened cloth is 200g / m2 and the thickness is 0.2mm; the surface density of the carbon fiber half-cut mesh is 50g / m2 and the thickness is 0.4mm. The incision length and incision spacing are 25mm.

[0054] Needle punching parameters: the needling density is 15 needles / cm2, the needling depth is 15mm, the half-cut mesh surface density is 50g / m2, the needle model is the medium needle 15×18×36×3C333 D24101, and one unit layer is punctured once.

[0055] Layer design: 5 layers of spread fabric plus 1 layer of half-cut mesh tire is a unit layer, the spread fabric is on the bottom and the half-cut mesh tire is on the top.

[0056] Comparative Example 1-1:

[0057] A traditional spread fabric plus a half-cut mesh layer, that is, a short fiber non-peeling needle-punched fabric with a carbon fiber spread fabric layer and a half-cut carbon fiber mesh layer on the surface.

[0058] Needle punching process: After each unit layer is needle punched, the half-cut mesh layer on the surface is retained, and then the next unit layer is laid for needle punching.

[0059] Material parameters: The surface density of the carbon fiber widened cloth is 200g / m2 and the thickness is 0.2mm; the surface density of the carbon fiber half-cut mesh is 50g / m2 and the thickness is 0.4mm. The incision length and incision spacing are 25mm.

[0060] Needle punching parameters: the needling density is 15 needles / cm2, the needling depth is 15mm, the half-cut mesh surface density is 50g / m2, the needle model is the medium needle 15×18×36×3C333 D24101, and one unit layer is punctured once.

[0061] Layer design: 3 layers of spread fabric + 1 layer of half-cut mesh tire as a unit layer, the spread fabric is on the bottom and the half-cut mesh tire is on the top.

[0062] Comparative Example 1-2:

[0063] A high-load-bearing needle-punched fabric based on short fiber stripping has only carbon fiber widened cloth on the surface and no carbon fiber mesh. The mesh used in the needle-punching of the fabric layer is a traditional complete mesh that has not been half-cut.

[0064] Needle punching process: After each unit layer is needle punched, the complete mesh layer on the surface is peeled off, and then the next unit layer is laid and needle punched and peeled off.

[0065] Material parameters: The density of the carbon fiber widened cloth is 200g / m2 and the thickness is 0.2mm; the density of the carbon fiber complete mesh tread is 50g / m2 and the thickness is 0.4mm.

[0066] Punching parameters: the punching density is 15 needles / cm2, the punching depth is 15mm, the density of the complete mesh surface is 50g / m2, the needle model is the medium needle 15×18×36×3C333 D24101, and one unit layer is punctured once.

[0067] Layer design: 5 layers of spread fabric + 1 layer of complete mesh tire is a unit layer, with the spread fabric at the bottom and the complete mesh tire at the top.

[0068] Example 2:

[0069] A high-load-bearing needle-punched fabric based on short fiber stripping, with only carbon fiber widened cloth on the surface and no carbon fiber mesh. The mesh used in the needle-punching of the fabric layer is a half-cut mesh with incisions. After the needling is completed, the fabric is RTM-compounded to form a composite material.

[0070] Needle punching process: After each unit layer is needled, the half-cut mesh layer on the surface is peeled off, and then the next unit layer is laid and peeled off by needling.

[0071] Material parameters: The surface density of the carbon fiber widened cloth is 200g / m2 and the thickness is 0.2mm; the surface density of the carbon fiber half-cut mesh is 50g / m2 and the thickness is 0.4mm. The incision length and incision spacing are 25mm.

[0072] Needle punching parameters: the needling density is 15 needles / cm2, the needling depth is 15mm, the half-cut mesh surface density is 50g / m2, the needle model is the medium needle 15×18×36×3C333 D24101, and one unit layer is punctured once.

[0073] Layer design: 5 layers of spread fabric + 1 layer of half-cut mesh tire is a unit layer, the spread fabric is on the bottom and the half-cut mesh tire is on the top.

[0074] Comparative Example 2-1:

[0075] A traditional spread fabric plus a half-cut mesh layer, that is, a short fiber non-peeling needle-punched fabric, with a carbon fiber spread fabric layer and a half-cut carbon fiber mesh layer on the surface. After the needling is completed, the fabric is RTM-compounded to form a composite material.

[0076] Needle punching process: After each unit layer is needled, the half-cut mesh layer on the surface is retained, and then the next unit layer is laid for needling.

[0077] Material parameters: The surface density of the carbon fiber widened cloth is 200g / m2 and the thickness is 0.2mm; the surface density of the carbon fiber half-cut mesh is 50g / m2 and the thickness is 0.4mm. The incision length and incision spacing are 25mm.

[0078] Needle punching parameters: the needling density is 15 needles / cm2, the needling depth is 15mm, the half-cut mesh surface density is 50g / m2, the needle model is the medium needle 15×18×36×3C333 D24101, and one unit layer is punctured once.

[0079] Layer design: 3 layers of spread fabric + 1 layer of half-cut mesh tire as a unit layer, the spread fabric is on the bottom and the half-cut mesh tire is on the top.

[0080] Comparative Example 2-2:

[0081] A high-load-bearing needle-punched fabric based on short fiber stripping. The surface only contains carbon fiber expanded cloth, and no carbon fiber mesh is present. The mesh used in the needle-punching of the fabric layer is a traditional complete mesh that has not been half-cut. After the needling is completed, the fabric is RTM-compounded to form a composite material.

[0082] Needle punching process: After each unit layer is needle punched, the complete mesh layer on the surface is peeled off, and then the next unit layer is laid and needle punched and peeled off.

[0083] Material parameters: The density of the carbon fiber widened cloth is 200g / m2 and the thickness is 0.2mm; the density of the carbon fiber complete mesh tread is 50g / m2 and the thickness is 0.4mm.

[0084] Punching parameters: the punching density is 15 needles / cm2, the punching depth is 15mm, the density of the complete mesh surface is 50g / m2, the needle model is the medium needle 15×18×36×3C333 D24101, and one unit layer is punctured once.

[0085] Layer design: 5 layers of spread fabric + 1 layer of complete mesh tire is a unit layer, with the spread fabric at the bottom and the complete mesh tire at the top.

[0086] The needle-punched fabric was subjected to interlayer peeling and in-plane tensile performance tests according to GJB 1867-94; the needle-punched composite material obtained by the RTM process was subjected to double cantilever beam (DCB) test according to GB / T 28891-2012 and in-plane tensile performance test according to GB / T1447-2005. Figure 4 As shown in the figure, the peeling test of the fabric is a test between two unit layers, from bottom to top, for a total of 3 layers; the tensile test of the fabric is a test of each unit layer after 3 interlayer peelings, from top to bottom; the DCB test position of the composite material is the middle layer of the board thickness; the tensile test of the composite material is the tensile test of a normal board.

[0087] Table 1 Peel strength between fabric layers

[0088]

[0089] Table 2 In-plane tensile strength of fabrics

[0090]

[0091] Table 3 Mode I interlaminar fracture toughness of composite materials

[0092] Serial number Mode I interlaminar fracture toughness GIC (mj / mm2) Example 2 0.93 Comparative Example 2-1 0.36 Comparative Example 2-2 0.73

[0093] Table 4 In-plane tensile strength of composite materials

[0094] Serial number In-plane tensile strength (Mpa) Example 2 651.06 Comparative Example 2-1 440.18 Comparative Example 2-2 600

[0095] Tables 1-4 above show a comparison of the mechanical properties of the fabrics and their composite materials. Examples 1, 2, Comparative Examples 1-2, and 2-2 are the staple fiber-stripping needle-punched fabrics and their composite materials described herein; Comparative Examples 1-1 and 2-1 are traditional spread-weave fabric + web-stitching laminated needle-punched fabrics and their composite materials, i.e., fabrics and their composite materials without web-stitching.

[0096] In Example 1 and Comparative Example 1-1, the web is peeled and not peeled, both under the premise of half-cutting. In Example 1 and Comparative Example 1-2, the web is peeled and the web is peeled. The comparison combination of the composite materials is the same as that of the fabric.

[0097] Table 1 shows the comparison of interlayer peeling strength of fabrics. Compared with Comparative Example 1-1, the interlayer peeling strength of Example 1 is increased by 42.3%; compared with Comparative Example 1-2, the interlayer peeling strength of Example 1 is increased by 74.7%.

[0098] Table 2 shows the comparison of the in-plane tensile strength of the fabrics. Compared with Comparative Example 1-1, the in-plane tensile strength of Example 1 increased by 84.1%; compared with Comparative Example 1-2, the in-plane tensile strength of Example 1 increased by 12.1%.

[0099] Table 3 shows the comparison of the interlaminar fracture toughness of composite materials. Compared with the comparative example 2-1, the interlaminar fracture toughness G ⅠC The interlaminar fracture toughness G of Example 2 was improved by 158.3%. ⅠC An increase of 27.3%.

[0100] Table 4 shows the comparison of the in-plane tensile strength of the composite materials. Compared with Comparative Example 2-1, the in-plane tensile strength of Example 2 increased by 47.9%; compared with Comparative Example 2-2, the in-plane tensile strength of Example 2 increased by 8.5%.

[0101] It can be seen from the above experimental results that the high-load-bearing needle-punched fabric structure based on short fiber stripping proposed in this paper has greatly improved the mechanical properties of needle-punched fabrics and their composite materials.

[0102] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the aforementioned specific embodiments. The aforementioned specific embodiments are merely illustrative and not restrictive. Persons skilled in the art, informed by the present invention, may devise various embodiments without departing from the spirit of the present invention and the scope of protection of the claims. All such embodiments fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping, characterized in that: The following steps are involved: S1, prepare raw materials: accurately cut the mesh according to the pre-designed half-cut trajectory to form a carbon fiber mesh and carbon fiber spread cloth of appropriate size in turn; the carbon fiber mesh is processed into a half-cut mesh; the S1 includes S1-1 designing the half-cut mesh and S1-2 cutting the carbon fiber mesh and carbon fiber spread cloth; S1-1 parametrically designs the half-cut trajectory of the carbon fiber mesh, and the half-cut mesh is to cut the carbon fiber mesh at equal intervals in the horizontal or vertical direction, and the trajectories of the previous row and the next row or the previous column and the next column are staggered, and the staggered distance is half of the spacing between the two incisions, generating an ordered arrangement set network with a number of fixed-value incisions; S1-2 transfers the half-cut cutting trajectory file and the raw material cutting trajectory file to the CNC numerical control cutting machine supporting software on the PC side, generates a file that can execute the cutting task, and then downloads the file from the PC side to the CNC numerical control cutting machine, and finally lays the raw material rolls of the carbon fiber mesh and the carbon fiber spread cloth horizontally on the cutting machine, and starts the machine to cut the raw materials; S2. Needle punching: stack several layers of carbon fiber spread fabric and a layer of carbon fiber mesh from bottom to top in sequence to form a unit layer, with the carbon fiber mesh located on the top of the unit layer; use a needling robot to needle punch the unit layer according to a pre-written needling program; S3. Electric stripping: use an electric clipper to remove the carbon fiber mesh on the top of the unit layer that has been needled to obtain a bottom unit layer consisting of only carbon fiber spread fabric; S4. Circular needling: continue to lay down the next unit layer in the fabric thickness direction of the bottom unit layer, where the carbon fiber mesh is placed at the same angle as the previous unit layer, raise the needling height of the stripping plate according to the actual thickness of the layer, and keep the needling trajectory in the horizontal plane unchanged to ensure that the needling robot performs in-situ needling. After the needling is completed, continue to use the electric clipper to remove the carbon fiber mesh on the top of the unit layer; repeat S4 until the needling forming of the target thickness of the entire fabric is completed.

2. The method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping according to claim 1, characterized in that: The half-cut trajectory parameters in S1-1 include the incision length L and the incision spacing b. The incision length is 15 to 35 mm, and the spacing between two adjacent incisions is 10 to 30 mm.

3. The method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping according to claim 1, characterized in that: The surface density of the carbon fiber mesh in S1-2 is 50-60g / m2; the structure of the carbon fiber widening cloth is plain weave, and the specifications of the widening cloth are grid width 8-9mm and surface density 200-205g / m 2 Or the grid width is 16-17mm, the surface density is 100-105g / m 2 Or the grid width is 20-21mm, the surface density is 80-85g / m 2 .

4. The method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping according to claim 1, characterized in that: The S2 includes S2-1 writing a needling program, S2-2 laying the needling raw materials and S2-3 needling; S2-1 uses the actual layer thickness value of the unit layer as the raised needling height of the robot end effector; and inputs the number of needles on the needle board, the adopted needling density value, the needling depth value and the needling starting point posture information into the needling robot programming software to generate a programmable needling execution program; S2-2 stacks the carbon fiber widened cloth and carbon fiber mesh tire cut in S1 into unit layers according to the designed laying order; S2-3 downloads the needling program generated in S2-1 to the robot teaching pendant, adjusts and calibrates the needling robot, and continuously needles the unit layer according to the written needling program.

5. The method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping according to claim 4, characterized in that: The number of needles in the needle plate of S2-1 is 47; the needle density can be selected from 10 to 30 needles / cm 2 ;Acupuncture depth 10~20mm.

6. The method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping according to claim 4, characterized in that: One unit layer in S2-2 can be composed of 3 to 5 layers of carbon fiber stretched fabrics and 1 layer of carbon fiber web.

7. The method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping according to claim 1, characterized in that: The blade head of the electric clipper in S3 is a combination of a static blade at the bottom and a dynamic blade at the top. When peeling, the blade head is placed on the bottom surface of the upper right corner of the carbon fiber mesh, so that the blade head cuts in at 20° relative to the length direction of the carbon fiber mesh; the blade head moves in an "S" shape, and the electric clipper moves forward to cut the needle-punched fiber bundle in the Z direction.

8. The method for preparing a high-load-bearing needle-punched fabric based on short fiber stripping according to claim 1, characterized in that: Before each needling in S4, the actual thickness value of the ply needs to be input into the needling robot programming software to generate a new programmable needling execution program, which is downloaded to the robot teaching pendant, and the needling robot is started to run the program to continuously needle the fabric.

9. A high-load-bearing needle-punched fabric based on short fiber stripping, characterized in that: The fabric is made using the preparation method according to any one of claims 1 to 8, wherein the fabric comprises several layers of carbon fiber spread fabrics and several needle-punched fiber bundles vertically inserted between the layers.

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