Aperture size control sheet

Abstract

The utility model discloses an aperture size control piece which is a piece body horizontally arranged in the length direction, the aperture size control piece comprises a working part and installation parts located at the two ends of the working part, the working part is connected with the installation parts, the working part is used for being placed in a gap-shaped fabric opening, the length of the working part in the weaving direction is W1, and W1 = L-B, the length of the fabric opening is L, B is equal to B1, B2 or B3, and t is the thickness of the working part; when the corner of the edge of the aperture size control piece is a right angle, B = B1, B1 = Q1 * t * 0.5, when the corner of the edge of the aperture size control piece is a chamfer, B = B2, B2 = Q2 * t * 0.5, Q2 is a sine value of chamfer taper, and when the corner of the edge of the aperture size control piece is a round corner, B = B3, B3 = Q3 * (t-r). And a compensation value B is set according to the edge of the aperture size control sheet, so that the geometric area deviation ratio of the polygonal core lattice prefabricated body and the set specification can be further reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of high-performance fiber weaving, and in particular relates to an aperture size control sheet. Background Art

[0002] In order to meet the material performance requirements of aerospace equipment, the research and development of composite materials with high specific strength, high specific modulus and low density has become a key area. Polygonal core lattice structural materials have the characteristics of light weight, high porosity and low density, and have become an important component of composite core materials for aviation. The polygonal core lattice materials currently widely used are mainly single-layer structural bonding, and the performance of the W-direction wall nodes of the polygonal core lattice is weak, forming a structural weak ring. With the development of space exploration, this structure has been difficult to meet performance requirements.

[0003] In order to improve the problem of weak W-direction wall connection performance of the existing polygonal core lattice structure, a polygonal core lattice preform with W-direction interlayer connection is obtained by three-dimensional weaving. The polygonal core lattice preform is composed of identical unit cells arranged and connected in an array, and openings are formed in the unit cells. This structure is used as a reinforcing material to further prepare a polygonal core lattice composite material.

[0004] For the three-dimensional weaving process, the four-step method is the overall process basis of three-dimensional weaving. The four-step three-dimensional weaving is currently a relatively mature one-piece molding process for special-shaped structure preforms. The four-step three-dimensional weaving uses a yarn carrier to carry the yarn and moves it in the X and Y directions according to the rules on the Cartesian machine. The overall braided preform is formed by the circular movement of the yarn carrier along the X and Y axes on the yarn carrier. Figure 2 The figure is a diagram of the weaving motion trajectory of the yarn carrier. When a certain row of yarn carriers is controlled to only allow it to move along a single Y-axis, multiple pieces of fabric will be split inside the preform. By controlling the fixed row interval and fixed row position, the opening and closing of the holes can be formed, and finally a polygonal core grid preform is generated.

[0005] In the prior art, although the weaving of polygonal core grid structure fabrics has been achieved, the semi-automatic production mode is generally used in actual processing to control the shape and weaving parameters of the woven fabric, which has become a key issue affecting the stability of the performance of polygonal core grid fabrics. In the existing four-step three-dimensional weaving polygonal core grid technology, the core mold is formed in the process (the core mold is formed in the process: that is, during the weaving process, each row of cells is completed and the core mold is inserted into the row of cells) to form the polygonal core grid fabric. This forming method will produce large fabric deformation under the action of gravity and tension, resulting in tension errors (such as Figure 4 As shown in the figure, the tension error is affected by the weaving process, operation technology and molding technology, and is difficult to predict, control and correct. This ultimately leads to inaccurate molding of the polygonal core structure, which seriously affects the performance of the finished material and limits the use scenarios.

[0006] For example: The patent with publication number CN115058825A (application number 202210635648.0) discloses a three-dimensional weaving method for a polygonal core grid structure, in which the fiber bundles are interwoven by rotating a planar yarn carrier, so that the fiber bundles form a vertically mounted polygonal core grid structure. CN115976729A (application number 202211730601.9) discloses a large-size polygonal core grid preform and a preparation method using array equipment for weaving, involving a four-step three-dimensional weaving process to form a polygonal core grid preform. The above application does not involve the shape control design of the three-dimensional woven polygonal core grid structure, lacks the structural design and control of the molded polygonal core grid structure, resulting in instability in the processing parameters and ultimately causing structural defects. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the utility model is to provide an aperture size control sheet.

[0008] The purpose of the utility model is achieved through the following technical solutions.

[0009] An aperture size control sheet is a sheet body arranged horizontally in the length direction, and the aperture size control sheet comprises: a working part and mounting parts located at both ends of the working part, the working part and the mounting part are connected, the working part is used to be placed in a fabric opening in the shape of a slit, the length of the working part along the weaving direction is W1, W1=LB, wherein the length of the fabric opening (slit) is L, B=B1, B2 or B3, and t is the thickness of the working part;

[0010] When the corner of the edge of the aperture size control sheet is a right angle, B = B1, B1 = Q1*t*0.5, where Q1 = 1.41,

[0011] When the corner of the edge of the aperture size control sheet is chamfered, B=B2, B2=Q2*t*0.5, where Q2 is the sine value of the chamfer taper,

[0012] When the corners of the edge of the aperture size control plate are rounded, B=B3, B3=Q3*(tr), where r is the fillet radius. When the fillet radius r is less than or equal to 0.5t, Q3 is 1.41; when the fillet radius r is greater than 0.5t and less than or equal to t, Q3 is 1; when the fillet radius r is greater than t, Q3 is 0.

[0013] In the above technical solution, the thickness of the aperture size control sheet is less than 2 mm.

[0014] In the above technical solution, there is a smooth transition between the mounting portion and the working portion.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] 1. The preparation method of the utility model realizes precise control of the aperture size of the polygonal core lattice preform by designing, calculating and adjusting the weaving parameters of the three-dimensional braided fabric. It solves the problems of large deviation between the design parameters and actual production parameters of the three-dimensional braided polygonal core lattice preform in the prior art, low production efficiency, and difficulty in controlling the fabric structure. It further improves processing efficiency and reduces processing allowance.

[0017] 2. The preparation method of the present invention adopts a two-step molding method, cooperates with the polygonal core lattice expander design, and adopts precise parameter design and flexible shape variation strategy to effectively improve the structural stability of the polygonal core lattice preform and reduce weaving damage, avoid defects caused by structural variation, further ensure the stability of the preform performance, and enhance the utilization value of the preform.

[0018] 3. Setting the compensation value B according to the edge of the aperture size control sheet can further reduce the geometric area deviation rate from the set specifications.

[0019] 4. According to the angle of the honeycomb core cell opening θ, the length of the flower section of the combined edge in the polygonal core cell preform and the length of the flower section of the free edge in the polygonal core cell preform are compensated in size, which can further reduce the geometric area deviation rate from the set specification.

[0020] 5. The utility model designs an opening auxiliary tool, which can better complete the preparation method of the utility model;

[0021] 6. In order to realize the preparation method of three-dimensional woven polygonal core lattice preform, a three-dimensional woven polygonal core lattice preform forming precise control tooling was designed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the structure of a precise shape-control tooling for forming a three-dimensional woven polygonal core preform;

[0023] Figure 2 It is the weaving motion trajectory diagram of the yarn carrier in the four-step three-dimensional weaving method;

[0024] Figure 3 It is a schematic diagram of the structure of a polygonal core lattice preform;

[0025] Figure 4 It is a schematic diagram of the tension error formed by the core mold forming method;

[0026] Figure 5 This is a structural diagram of the preform in step 1 of the method for preparing a three-dimensional woven polygonal core lattice preform in Example 1;

[0027] Figure 6 It is a schematic diagram of the structure of a polygonal core lattice preform (the opening shape in a unit cell is a hexagon);

[0028] Figure 7 The relationship between the yarn carrier and the formed fabric corresponding to each stage;

[0029] Figure 8 It is a schematic diagram of the structure of the aperture size control sheet;

[0030] Fig. 9 It is a schematic diagram of the structure of the aperture size control sheet;

[0031] Fig.10 is the honeycomb core opening θ;

[0032] Fig.11 is the honeycomb core opening θ;

[0033] Fig.12 is a schematic diagram of the structure of the opening auxiliary tool, wherein a is a main view, b is a side view, c is a top view, and d is a stereogram;

[0034] Fig.13 A schematic diagram of the structure of a precise shape-control tooling for forming a three-dimensional woven polygonal core preform;

[0035] Fig.14 It is a structural schematic diagram of a precise shape control tooling for forming a three-dimensional woven polygonal core preform, wherein a is the state when the first fabric of the first row of weaving is opened, and b is the state when the second fabric of the first row of weaving is opened;

[0036] Fig.15 (a) side view and (b) stereogram of the reference plane frame;

[0037] Fig.16 The structural diagram of the positioning belt for length control;

[0038] Fig.17 The structural diagram of the positioning belt for length control;

[0039] Fig.18 The structural diagram of the positioning belt for length control;

[0040] Fig.19 is a structural diagram of the aperture size control sheet;

[0041] Fig. 20 The figure is a structural diagram of the opening auxiliary tool fixed to the core mold.

[0042] Among them, 1: introduction part, 2: hole expansion part, 3: height control frame, 4: reference plane frame, 5: length control positioning belt, 6: first connecting rod, 7: initial position control sheet, 8: aperture size control sheet, 8-1: installation part, 8-2: working part, 9: core mold, 10: first through hole, 11: second through hole, 12: second connecting rod; DETAILED DESCRIPTION

[0043] The technical solution of the utility model is further explained below in conjunction with the accompanying drawings and embodiments.

[0044] Example 1

[0045] A method for preparing a three-dimensional woven polygonal core preform, such as Figure 6 and Figure 3 As shown, the polygonal core lattice preform is formed by arranging and connecting identical unit cells in an array, and an opening is formed in the unit cell. The shape of the opening in the unit cell is a hexagon, a quadrilateral, a circle, an octagon, a decagon or a concave hexagon;

[0046] The length of the bonding edge of the unit cell is L b , the length of the free edge of the unit cell is L f ;

[0047] The method for preparing a three-dimensional woven polygonal core preform comprises the following steps:

[0048] Step 1: Use the three-dimensional weaving four-step method to weave Figure 5 The preform shown in the figure, wherein the preform is formed with multiple columns of first fabric opening groups and multiple columns of second fabric opening groups along its width direction, a column of second fabric opening groups is arranged between every two adjacent first fabric opening groups, the first fabric opening groups are first fabric openings formed on the preform at intervals along the weaving direction, the second fabric opening groups are second fabric openings formed on the preform at intervals along the weaving direction, the first fabric openings and the second fabric openings are both gaps, the lengths of the first fabric openings and the second fabric openings are the same and are both L, the upper part of each first fabric opening is opposite to the lower part of each second fabric opening in the second fabric opening groups on both sides adjacent to it, and the relative parts of the preform are upper overlapping parts, and the length of the upper overlapping part is L f The lower part of each first fabric opening is opposite to the upper part of each second fabric opening in the second fabric opening groups on both sides thereof, and the preform of the opposite part is the lower overlap part, and the length of the lower overlap part is L f Each first fabric opening and the non-opposite part of the second fabric openings in the second fabric opening groups on both sides thereof are first non-overlapping parts, and the length of the first non-overlapping parts is L. b =L-2L f Each second fabric opening and the preform of the non-opposite part of the first fabric opening in the first fabric opening group on both sides adjacent to it are the second non-overlapping parts, and the length of the second non-overlapping parts is L b .

[0049] In order to form the gap, the three-dimensional weaving four-step weaving method includes: a first polygonal core lattice combined edge forming stage, a first polygonal core lattice free edge forming stage, a second polygonal core lattice combined edge forming stage, and a second polygonal core lattice free edge forming stage, and the first fabric opening and the second fabric opening are formed by the first polygonal core lattice combined edge forming stage, the first polygonal core lattice free edge forming stage, the second polygonal core lattice combined edge forming stage, and the second polygonal core lattice free edge forming stage;

[0050] The first polygonal core lattice combined edge forming stage is used to form the second non-overlapping portion in the preform; the first polygonal core lattice free edge forming stage is used to form the upper overlapping portion in the preform; the second polygonal core lattice combined edge forming stage is used to form the first non-overlapping portion in the preform; the second polygonal core lattice free edge forming stage is used to form the lower overlapping portion in the preform;

[0051] The relationship between the yarn carrier and the completed preform at each stage is as follows: Figure 7 As shown, Figure 7 The columns marked with a, b and c are the fixed column positions of the yarn carriers.

[0052] For the first polygonal core grid combined edge forming stage, the fixed columns of the yarn carriers are numbered as follows: the first column, the last column, and all columns whose column numbers X of the yarn carriers meet the following formula:

[0053] (X-1) / (2*n t +2) = integer

[0054] For the first polygonal core grid free edge forming stage, the fixed columns of the yarn carriers are numbered as follows: the first column, the last column, and all columns whose column numbers X of the yarn carriers meet the following formula:

[0055] (X-1) / (n t +1) = integer

[0056] For the second polygonal core grid combined edge forming stage, the fixed columns of the yarn carriers are numbered as follows: the first column, the last column, and all columns whose column numbers X of the yarn carriers meet the following formula:

[0057] (X+n t ) / (2*n t +2) = integer

[0058] For the second polygonal core grid free edge forming stage, the fixed column number of the yarn carrier is the same as that of the first polygonal core grid free edge forming stage;

[0059] Among them, n t is the number of yarn carrier columns corresponding to a single free edge in the polygonal core lattice preform;

[0060] When the second polygonal core grid free edge forming stage is completed and the first fabric opening is not sealed, an aperture size control sheet is placed into the first fabric opening that is not sealed in the row, and the aperture size control sheet is parallel to the length direction of the first fabric opening;

[0061] When the first polygonal core cell free edge forming stage is completed and the second fabric opening is not sealed, inserting an aperture size control sheet into the unsealed second fabric opening of the row, wherein the aperture size control sheet is parallel to the length direction of the second fabric opening;

[0062] The thickness of the aperture size control sheet is less than 2 mm.

[0063] After all the aperture size control sheets are placed into the preform, the length of the relative parts of any two adjacent rows of aperture size control sheets along the weaving direction is L f The length of the edges of each two adjacent rows of aperture size control sheets in the same column along the weaving direction is L b ;

[0064] Step 2, after the three-dimensional weaving four-step method is completed, the aperture size control sheet is taken out row by row, and the opening auxiliary tool (such as Fig. 20 As shown), the opening auxiliary tool fills the core mold into the first fabric opening / the second fabric opening and makes the first fabric opening / the second fabric opening respectively form a single cell opening of the polygonal core lattice preform to obtain the polygonal core lattice preform.

[0065] The opening auxiliary tool and the core mold can be fixed in a variety of ways, such as gluing or magnetic attraction, or they can be integrally formed.

[0066] Preferably, the surface of the pore size control sheet is covered with a release cloth or coated with a release agent to further reduce weaving damage.

[0067] Preferably, the surfaces of the core mold and the opening auxiliary tool are smooth, and more preferably, the surfaces are covered with a release cloth or soaked with a release agent.

[0068] Example 2

[0069] On the basis of Example 1, Figure 8 , Fig. 9 and Fig.19 As shown, the aperture size control sheet is a single piece. The aperture size control sheet cannot be deformed during use, so a certain thickness is required. This means that the variation of the polygonal core lattice structure caused by the thickness of the aperture size control sheet must be considered and compensated:

[0070] The aperture size control sheet 8 includes: a working portion 8-2 and mounting portions 8-1 located at both ends of the working portion, the working portion 8-2 and the mounting portion 8-1 are connected, the working portion 8-2 is used to be placed in the first fabric opening / second fabric opening, the mounting portion 8-1 is used to fix the aperture size control sheet in the first fabric opening / second fabric opening after the aperture size control sheet is placed in the first fabric opening / second fabric opening, the length of the working portion along the weaving direction is W1, and the compensation value B is set according to the edge of the aperture size control sheet, W1=LB, wherein B=B1, B2 or B3; t is the thickness of the working portion;

[0071] When the corner of the edge of the aperture size control sheet is a right angle, B = B1, B1 = Q1*t*0.5, where Q1 = 1.41,

[0072] When the corner of the edge of the aperture size control sheet is chamfered, B=B2, B2=Q2*t*0.5, where Q2 is the sine value of the chamfer taper C (i.e., for a chamfer taper of 60 degrees, Q2 is 2),

[0073] When the corners of the edge of the aperture size control plate are rounded, B=B3, B3=Q3*(tr), where r is the fillet radius. When the fillet radius r is less than or equal to 0.5t, Q3 is 1.41; when the fillet radius r is greater than 0.5t and less than or equal to t, Q3 is 1; when the fillet radius r is greater than t, Q3 is 0.

[0074] Q1, Q2 and Q3 are compensation coefficients.

[0075] The length of the mounting portion along the weaving direction is W2. Figure 8 As shown, when W2 is less than W1, W2 is less than or equal to L b .

[0076] like Fig. 9 As shown, when W2 is greater than W1, 6mm≤W2<12mm.

[0077] There is a smooth transition between the installation part and the working part.

[0078] Example 3

[0079] On the basis of Example 2, according to the angle of the honeycomb core cell opening θ, the length of the node of the combined edge in the polygonal core cell preform and the length of the node of the free edge in the polygonal core cell preform are compensated in size to reduce the size variation after the hole is expanded off the machine. In order to make the unit cell opening of the polygonal core cell preform obtained by the three-dimensional woven polygonal core cell preform preparation method as close as possible to the set specification, it is necessary to enlarge the node length of the combined edge and reduce the node length of the free edge.

[0080] When the honeycomb core opening θ is an acute angle or a right angle (θ is less than or equal to 90 degrees), the change in the length of the polygonal core wall caused by tension can be ignored, and only the difference in the position of the honeycomb core opening is compensated. b ′ and the length l of the free edge in the method for preparing a three-dimensional braided polygonal core lattice preform f 'as follows:

[0081] l b ′=[k b / (k b -1 / 2)]*l b

[0082] l f ′=[k f / (k f +1 / 2)]*l f

[0083] When the honeycomb core opening θ is an obtuse angle or a straight angle (90 degrees <θ ≤ 180 degrees), the change in the length of the polygonal core wall caused by tension needs to be considered, and its compensation value is 1 / 2. At the same time, the shortening of the length of the bonding edge caused by the thickness of the single cell wall must also be considered. b ′ and the length l of the free edge in the method for preparing a three-dimensional braided polygonal core lattice preform f 'as follows:

[0084] l b ′=[k b / (k b -1)+(1 / 2*T b ) / k b ]*l b

[0085] l f ′=[k f / (k f +1)]*l f

[0086] When the honeycomb core opening θ>180 degrees, the free edge length elongation caused by the cell wall thickness must be considered on the basis of the obtuse angle. b ′ and the length l of the free edge in the method for preparing a three-dimensional braided polygonal core lattice preform f 'as follows:

[0087] l b ′=[k b / (k b -1)+(1 / 2*T b) / k b ]*l b

[0088] l f ′=[k f / (k f +1)-(1 / 2*T b ) / k f ]*l f

[0089] Among them, k b is the number of nodes of the combined edge, k f is the number of nodes on the free edge, l b is the theoretical value of the node length of the combined edge in the polygonal core lattice preform (i.e., the node length of the combined edge determined according to the specifications of the polygonal core lattice preform set before weaving), l f is the theoretical value of the node length of the free edge in the polygonal core lattice preform (i.e., the node length of the free edge determined according to the specifications of the polygonal core lattice preform set before weaving); T b is the wall thickness of the joining edge.

[0090] The honeycomb core opening θ of the polygonal core preform with different unit cell shapes is as follows Fig.10 and Fig.11 shown.

[0091] Example 4

[0092] Based on Example 3, the structural diagram of the opening auxiliary tool is as follows Fig.12 As shown, it includes: an introduction part 1 and a reaming part 2, the introduction part 1 and the reaming part 2 are connected, the introduction part and the reaming part are arranged along the length direction of the opening auxiliary tool, the rear end of the introduction part is fixedly installed with the front end of the reaming part, the introduction part is a sheet body with a gradually decreasing width from the back to the front, and the edge of the gradually decreasing width is a smooth line (the smooth line is a straight line or an arc), and the thickness of the introduction part is the same as the aperture size control sheet;

[0093] After the introduction portion enters the first fabric opening / the second fabric opening, the plane where the introduction portion is located is parallel to the length direction of the first fabric opening / the second fabric opening; the shape of the rear end face of the hole-expanding portion is the same as the shape of the unit cell opening of the polygonal core lattice preform, so that after the introduction portion brings the hole-expanding portion into the first fabric opening / the second fabric opening, the shape of the rear end face of the hole-expanding portion in the first fabric opening / the second fabric opening is the same as the shape of the unit cell opening (the shape of the rear end face of the hole-expanding portion is the same as the shape of the core mold to which it is fixed);

[0094] The circumference of the rear end surface shape of the introduction portion is 2L.

[0095] With the center line of the length direction of the opening auxiliary tool as the axis, all circumferences of the expansion part are the same, which is 2L.

[0096] The lead-in portion is located on the plane where the axis is located.

[0097] When the opening auxiliary tool is fixedly mounted on the core mold 9, the length direction of the core mold is parallel to the length direction of the opening auxiliary tool.

[0098] Since the introduction part is a single piece, the opening auxiliary tool is a smooth transition structure composed of the rear end surface of the introduction part and the expansion part, and the edge of the introduction part is chamfered or rounded to ensure smooth entry into the first fabric opening / the second fabric opening. The cross-sectional setting of the opening auxiliary tool should follow the following rules: the cross-section of the introduction part can be semicircular, semi-elliptical or rhombus-shaped, and the introduction part can be selected in different shapes for different shapes of the unit cell opening. If the unit cell opening is a quadrilateral, the introduction part is preferably a rhombus, and if the unit cell opening is a hexagon, the introduction part is preferably a semicircle.

[0099] Example 5

[0100] In order to realize the preparation method of three-dimensional woven polygonal core preform, the following design is made: Figure 13 to Figure 18 , Figure 1 The three-dimensional woven polygonal core lattice preform forming precise shape control tooling shown in the figure comprises: a frame, at least one yarn hanging rod (not shown in the figure), multiple mounting parts and multiple aperture size control sheets, the yarn hanging rod is fixedly mounted on the frame, and each mounting part is used to fix an aperture size control sheet on the frame during the weaving process.

[0101] The method for using the three-dimensional woven polygonal core lattice preform forming precision control tooling includes: hoisting the three-dimensional woven polygonal core lattice preform forming precision control tooling on the workstation base, weaving, inserting the aperture size control sheet into the fabric opening (first fabric opening / second fabric opening) of the preform formed by weaving during the weaving process, and fixing the aperture size control sheet on the frame. After weaving is completed, take out the aperture size control sheet.

[0102] Preferably, each mounting member includes two first connecting rods 6 parallel to the yarn hanging rod, and a first through hole for passing the first connecting rods 6 is formed on the frame. The number of first through holes on the frame corresponding to each first connecting rod is two (each first connecting rod has two first through holes at both ends passing through each first connecting rod). A second through hole for passing the first connecting rod is formed on each of the two mounting parts of the aperture size control plate 8, and each second through hole of the aperture size control plate passes through a first connecting rod and each of the two ends of the first connecting rod passes through a first through hole.

[0103] Preferably, the frame includes: a height control frame 3, two reference plane frames 4 and four length control positioning belts 5. The two reference plane frames are arranged in parallel and installed at the bottom of the height control frame. Each reference plane frame is vertically fixed with two parallel length control positioning belts. The two reference plane frames are used to fix the yarn hanging rod (the two ends of the yarn hanging rod are respectively fixed to a reference plane frame), and the length control positioning belt is used to fix the aperture size control piece. The first through hole is located on the length control positioning belt.

[0104] Preferably, the height control frame includes: a planar part and a fixing part, wherein the fixing part is fixed on the upper surface of the planar part, the fixing part is used to be fixed to the workstation base and then to suspend the three-dimensional woven polygonal core grid preform forming precision control tooling, and the planar part is used to install the reference plane frame.

[0105] Preferably, the two length control positioning belts on each reference plane frame are fixed to the reference plane frame by bolts or slide rails (locking).

[0106] Preferably, the two reference plane frames are fixed on the height control frame by bolts or slide rails (locking).

[0107] Preferably, the length control positioning belts on the two reference plane frames are arranged opposite to each other, and the two ends of each first connecting rod are respectively fixed on two length control positioning belts arranged opposite to each other on the two reference plane frames.

[0108] Preferably, each length control positioning belt has at least one row of first through holes.

[0109] Preferably, when L is less than 6 mm, each length control positioning belt has at least two rows of first through holes, and the multiple rows of first through holes on each length control positioning belt are staggered.

[0110] Preferably, when the first through holes of each length control positioning belt are in a row, the length of each first through hole on the length control positioning belt and the first through hole of the adjacent row directly below it along the weaving direction is L h , L h =1 / 2*(L B +2*L F ), L B is the length of the joint edge of the polygonal core preform, L f is the length of the free edge of the polygonal core preform.

[0111] Preferably, when the first through holes of each length control positioning belt are arranged in multiple rows, the length of each first through hole on the length control positioning belt and the first through hole closest to the adjacent row in a straight line along the weaving direction is L h (like Fig.18 shown), L h =1 / 2*(Lb +2*L f ), L b is the length of the joint edge of the polygonal core preform, L F is the length of the free edge of the polygonal core preform.

[0112] Preferably, it also includes: an initial position control piece 7, which is used to be fixed to two length control positioning belts fixed on the same reference plane frame. The position where the initial position control piece is fixed to the length control positioning belt is a fixed position, and the distance between the two length control positioning belts on the same reference plane frame can be quickly located through the fixed position.

[0113] Preferably, the two reference plane frames share the same initial position control sheet or each uses an initial position control sheet. When the two reference plane frames share the same initial position control sheet, two fixed positions on the initial position control sheet each pass through a second connecting rod 12, and the two ends of each second connecting rod are respectively fixed to two opposite length control positioning belts on different reference plane frames.

[0114] "When W2 is less than W1, W2 is less than or equal to L b The arrangement of " can avoid the situation where the aperture size control sheet covers the first through hole 10.

[0115] like Fig.19 As shown, the length of the working portion of the aperture size control sheet perpendicular to the weaving direction is L2, L2 is greater than or equal to the depth H of the polygonal core cell preform, and the length of the aperture size control sheet perpendicular to the weaving direction is L1.

[0116] The diameter of the first through hole is The diameter of the second through hole 11 is

[0117]

[0118] The number of the second through holes on each mounting portion of the aperture size control sheet is preferably three.

[0119] like Fig.16 and Fig.17 As shown, each length control positioning belt can be directly fixed on the reference plane frame ( Fig.16 ) or fixed on the reference plane frame through other positioning structures ( Fig.17 ).

[0120] Example 6

[0121] Set the specifications of the polygonal core preform: the shape of the opening in the unit cell is hexagonal, and the length of the unit cell's joint edge is L b =9mm, the length of the free edge of the unit cell is Lf =9mm; n t 1; the length of the flower node of the joint edge is 1.5mm, and the length of the flower node of the free edge is 1.5mm. The width of the flower node is 1mm. The wall thickness T of the joint edge b 0.2mm. Number of nodes k on the combined edge b is 6, and the number of flower nodes on the free edge is k f The number of the polygonal core lattice preform is 6. The polygonal core lattice preform is prepared according to the preparation method in Example 1, the corners of the edges of the aperture size control sheet are right angles, the length of the working portion along the weaving direction is L=27 mm (i.e., the edge of the aperture size control sheet is not compensated), and the thickness t of the aperture size control sheet is 1 mm;

[0122] The geometric area deviation rate of the unit cell in the polygonal core lattice preform obtained by the preparation method in Example 1 and the set specification is 7.1%.

[0123] Example 7

[0124] A method for preparing a three-dimensional woven polygonal core lattice preform is basically the same as Example 6, with the only difference being that: the length of the working portion along the weaving direction is W1, W1=LB, B=B1, B1=Q1*t*0.5, wherein Q1=1.41; and the geometric area deviation rate of a unit cell in the obtained polygonal core lattice preform from the set specification is 3.2%.

[0125] Example 8

[0126] A method for preparing a three-dimensional woven polygonal core lattice preform is basically the same as Example 7, the only difference being that the length of the flower node of the combined edge in the method for preparing a three-dimensional woven polygonal core lattice preform in Example 7 is used as the theoretical value of the length of the flower node of the combined edge in the polygonal core lattice preform in this embodiment, and the length of the flower node of the free edge in the method for preparing a three-dimensional woven polygonal core lattice preform in Example 7 is used as the theoretical value of the length of the flower node of the free edge in the polygonal core lattice preform in this embodiment. The length of the flower node of the combined edge in the method for preparing a three-dimensional woven polygonal core lattice preform in this embodiment is l b ′ and the length l of the free edge in the method for preparing a three-dimensional braided polygonal core lattice preform f 'as follows:

[0127] l b ′=[k b / (k b -1)+(1 / 2*T b ) / k b ]*l b

[0128] l f ′=[k f / (k f +1)]*lf

[0129] Among them, k b is the number of nodes of the combined edge, k f is the number of nodes on the free edge, l b is the theoretical value of the length of the junction edge in the polygonal core preform, l f is the theoretical value of the node length of the free edge in the polygonal core lattice preform; T b is the wall thickness of the joining edge.

[0130] In this embodiment, b ′=1.82mm,l f ′=1.28mm.

[0131] The geometric area deviation rate of the unit cell in the polygonal core lattice preform obtained in this embodiment and the set specification is 1.8%.

[0132] Comparative Example 1

[0133] A method for preparing a polygonal core lattice preform. The specifications of the polygonal core lattice preform set in this comparative example are the same as those set in Example 6. The only difference lies in the preparation method. This comparative example directly adopts the core mold forming method (without using an aperture size control sheet).

[0134] The geometric area deviation rate of the unit cell in the polygonal core lattice preform obtained in this embodiment and the set specification is 16%.

[0135] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be done by other technical personnel in this field without expending creative labor falls within the protection scope of the present invention.

Claims

1. An aperture size control sheet, characterized in that: It is a sheet body arranged horizontally in the length direction, and the aperture size control sheet comprises: a working part and mounting parts located at both ends of the working part, the working part and the mounting part are connected, the working part is used to be placed in the fabric opening in the shape of a slit, and the length of the working part along the weaving direction is W1, W1=LB, wherein the length of the fabric opening is L, B=B1, B2 or B3, and t is the thickness of the working part; When the corner of the edge of the aperture size control sheet is a right angle, B = B1, B1 = Q1*t*0.5, where Q1 = 1.41, When the corner of the edge of the aperture size control sheet is chamfered, B=B2, B2=Q2*t*0.5, where Q2 is the sine value of the chamfer taper, When the corners of the edge of the aperture size control plate are rounded, B=B3, B3=Q3*(tr), where r is the fillet radius. When the fillet radius r is less than or equal to 0.5t, Q3 is 1.41; when the fillet radius r is greater than 0.5t and less than or equal to t, Q3 is 1; when the fillet radius r is greater than t, Q3 is 0.

2. The aperture size control sheet according to claim 1, characterized in that: The thickness of the aperture size control sheet is less than 2 mm.

3. The aperture size control sheet according to claim 1, characterized in that: There is a smooth transition between the installation part and the working part.

Images