Preparation method of three-dimensional spacer fabric with circular structure

Abstract

The invention belongs to the technical field of textile, and relates to a preparation method of a three-dimensional spacer fabric with a circular structure, which specifically comprises the following steps: weaving an outer woven tube by using a group of yarns a, synchronously weaving an inner woven tube by using a group of yarns b, sleeving the inner woven tube with the outer woven tube, in the weaving process, a plurality of spacer filaments are inserted between the interweaving points formed by the yarn a and the interweaving points formed by the yarn b, the spacer filaments are repeatedly inserted along with the weaving process, and the three-dimensional spacer fabric of the circular structure is obtained after weaving is finished. The method is simple, the three-dimensional spacer fabric of the circular structure can be efficiently prepared, and the spacing of the three-dimensional spacer fabric of the circular structure is easy to adjust.

Description

Technical Field

[0001] The invention belongs to the technical field of textiles and relates to a method for preparing a circular structured three-dimensional spacer fabric. Background Art

[0002] Circular structure three-dimensional spacer fabric is a textile material with a specific shape and structure. It contains a spacer layer inside, which makes the fabric have good air permeability and elasticity while maintaining a certain thickness. This type of fabric has a wide range of applications in many fields, such as wrapping materials for sports equipment, supporting structures for medical equipment, and sound insulation materials for automotive interiors. Circular structure three-dimensional spacer fabric is favored by the market because it can provide stable support and comfortable use experience.

[0003] However, the spacer fabrics produced by traditional weaving technology are usually planar structures and cannot meet the application occasions that require circular structures.

[0004] In order to overcome the limitations of traditional weaving technology, patent application CN1431351A and literature (Research on the weaving process and performance of circular weft-knitted spacer fabrics [D]. Donghua University, 2007.) both successfully prepared circular structure three-dimensional spacer fabrics using circular knitting machines. However, this preparation method requires strict control of various parameters of the circular knitting machine during the weaving process, such as needle pitch, yarn tension, etc., to ensure the quality and performance of the fabric, and the production process is relatively complicated.

[0005] Therefore, it is necessary to develop a method that can efficiently prepare circular structured three-dimensional spacer fabrics. Summary of the invention

[0006] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing a circular structured three-dimensional spacer fabric.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A preparation method of a circular structure three-dimensional spacer fabric, using a group of yarns a to weave an outer braided tube, and simultaneously using a group of yarns b to weave an inner braided tube, the outer braided tube is sleeved on the inner braided tube and the inner diameter of the outer braided tube is larger than the outer diameter of the inner braided tube, during the weaving process, multiple spacer wires are inserted between the interlacing points formed by the yarns a and the interlacing points formed by the yarns b, and as the weaving process proceeds, the spacer wires are repeatedly inserted, and the circular structure three-dimensional spacer fabric is obtained after the weaving is completed.

[0009] As the preferred technical solution:

[0010] A method for preparing a circular structure three-dimensional spacer fabric as described above, controlling a group of yarn carriers a distributed in an annular shape to rotate around a vertical virtual axis, driving a group of yarns a to be interlaced, and synchronously controlling a group of yarn carriers b distributed in an annular shape and located inside the yarn carriers a to rotate around the virtual axis, driving a group of yarns b to be interlaced;

[0011] When the yarn carrier a and the yarn carrier b rotate one circle around the virtual axis, the yarn a completes multiple interweaving to form m interweaving points a, and the yarn b completes multiple interweaving to form m interweaving points b, and the m interweaving points a are arranged at intervals from the m interweaving points b, where m is a positive integer;

[0012] Select n interweaving points a and n interweaving points b from m interweaving points a and m interweaving points b respectively to form multiple pairs of interweaving points a and interweaving points b. For each pair of interweaving points a and interweaving points b, insert a spacer wire between the two when they are first formed, and then continue weaving. After at least one new pair of interweaving points a and interweaving points b is formed directly below the pair of interweaving points a and interweaving points b, insert the spacer wire between the latest pair of interweaving points a and interweaving points b, and repeat the process until the weaving is completed.

[0013] In the preparation method of a circular structure three-dimensional spacer fabric as described above, the n interweaving points a are numbered from 1 to n in the order of appearance, and the n interweaving points b are numbered from 1 to n in the order of appearance. The i-th interweaving point a and the i-th interweaving point b form a pair of interweaving points a and b for inserting spacer wires, i=1,…,n, so that parallel spacer wires can be formed.

[0014] According to the preparation method of a circular structure three-dimensional spacer fabric as described above, n interweaving points a are numbered from 1 to n in the order of appearance, and n interweaving points b are numbered from 1 to n in the order of appearance, the j+1th interweaving point a and the jth interweaving point b form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2th interweaving point b, the j+1th interweaving point b and the jth interweaving point a form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2th interweaving point a, j=1,…,n-2, so that cross-type spacer wires can be formed.

[0015] According to the preparation method of a circular structure three-dimensional spacer fabric as described above, n interweaving points a are numbered from 1 to n in the order of appearance, and n interweaving points b are numbered from 1 to n in the order of appearance, the i-th interweaving point a and the i-th interweaving point b form a pair of interweaving points a and b for inserting spacer wires, i=1,…,n, at the same time, the j+1-th interweaving point a and the j-th interweaving point b form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2-th interweaving point b, the j+1-th interweaving point b and the j-th interweaving point a form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2-th interweaving point a, j=1,…,n-2, so that a composite spacer wire can be formed.

[0016] In the method for preparing a circular structure three-dimensional spacer fabric as described above, n=m.

[0017] The preparation method of the circular structure three-dimensional spacer fabric as described above adopts a hexagonal three-dimensional braiding machine, wherein the yarn carriers in the hexagonal three-dimensional braiding machine are distributed in r layers, and the number of the layers increases from the inside to the outside, the yarn carrier b is the yarn carrier of the r1th layer, the yarn carrier a is the yarn carrier of the r2th layer, and 3≤r1 <r2≤m。

[0018] The core of the hexagonal 3D braiding machine is a unique hexagonal cam arrangement, which allows each cam to carry up to six yarn carriers, and the yarn carriers can move in six different planar directions. The papers "Novel three-dimensional braiding approach and its products [C] / / 17th International Conference on Composite Materials. Edinburgh, UK: ICCM, 2009: 27-31.", "Hexagonal braiding process, structure and performance and integrated design of braided structure composite materials [D]. Donghua University, 2013." and "Construction and application of a new type of hexagonal 3D braiding machine [J]. Textile Guide, 2013, (04): 80-84." have all published hexagonal 3D braiding machines.

[0019] The present invention controls the number of layers where the yarn carrier b is located to be at least 3 because if the number of layers where the yarn carrier b is located is less than 3, the movement trajectory of the yarn carrier at the corner of the knitting chassis is complex and the efficiency is low.

[0020] In the method for preparing a circular structure three-dimensional spacer fabric as described above, the difference between r2 and r1 is not less than 2; and the thickness of the circular structure three-dimensional spacer fabric exceeds 100 mm.

[0021] In the textile field, spacer fabrics with a finished product thickness of more than 100mm are usually defined as super-large-gauge spacer fabrics. The thickness of this fabric is usually between 100mm and 300mm, and in rare cases it can even reach more than 650mm. Super-large-gauge spacer fabrics are composed of two systems of surface yarns and one system of spacer yarns, forming a three-layer structure: upper surface layer, spacer layer and lower surface layer. The spacer yarns run through the two surface layers according to a certain rule, thereby forming a spacer layer with a certain thickness and spatial structure between the two surface layers of the fabric. The arrangement of spacer yarns in the fabric mainly includes three types: mono-oblique, cross and upright. Due to its super-large spacing, this fabric has shown unique and wide application value and has become a multifunctional and high-performance textile material.

[0022] At present, the forming technologies of super-large gauge spacer fabrics are mainly divided into warp knitting and weaving.

[0023] Extra-large gauge warp knitted spacer fabrics are woven on improved double needle bed Raschel warp knitting machines. When weaving, the warp knitting machine commonly used is E18 to E22, the working width range is between 1905mm (75 inches) and 3505mm (138 inches), and it is usually equipped with 5 to 6 combs. During the weaving process, the first two combs form loops on the front needle bed to form a surface fabric; the second two combs form loops on the back needle bed to form another surface fabric; and the middle 1 to 2 combs form loops on the front and back needle beds in turn to form a spacer layer, thus forming a 3D fabric with a certain spatial structure. The thickness of the fabric can be easily adjusted by adjusting the distance between the two grid-shaped knock-over plates. According to the configuration of the filaments (monofilament or multifilament) in the spacer layer, the spacer yarn group can be divided into several types such as V-shaped, X-shaped, I-shaped and IXI-shaped.

[0024] Super-gauge woven spacer fabric is a new type of fabric structure developed based on weaving processing technology, mainly woven using rapier looms. It is a three-dimensional woven fabric formed by connecting two parallel fabric surface structures, one above the other, with a group of spacer yarns or a group of spacer tissues. Different connection methods of the spacer layer can make the woven spacer fabric produce different interface structures, the most common of which are "V" shape, "X" shape and "8" shape.

[0025] However, the super-large-gauge spacer fabrics obtained by the two molding methods are both planar structures and cannot be applied to scenes requiring circular structures. In the current super-large-gauge spacer fabric molding technology, there are no related reports on circular structures. Therefore, for the application fields that require the preparation of super-large-gauge spacer fabrics with circular structures, the existing molding technology cannot meet their needs. The present invention solves this problem, and it realizes the efficient and accurate preparation of super-large-gauge spacer fabrics with circular structures.

[0026] In the present invention, the key factor affecting the thickness of the circular structure three-dimensional spacer fabric is the number of distribution layers of the yarn carriers. With each additional layer of yarn carrier, the fabric will increase a fixed contribution in the thickness direction. This contribution is recorded as "single-layer contribution thickness" and represented by "T". During the weaving process, since the difference between r2 and r1 is not less than 2, it means that at least two Ts are used to construct the thickness of the fabric. Therefore, the thickness of the circular structure three-dimensional spacer fabric will be greater than or equal to 2×T, that is, the thickness of the fabric at this time exceeds 100mm, which meets the definition of super-large gauge spacer fabric. In addition, the parameters that affect the density of the circular structure three-dimensional spacer fabric are mainly the thickness, quantity, weaving angle, and drafting speed of the yarn. The present invention can adjust these parameters during the weaving process to improve the control of the density of the circular structure three-dimensional spacer fabric, and it can also be processed and formed without the aid of auxiliary tools such as mandrels.

[0027] In the method for preparing a circular structure three-dimensional spacer fabric as described above, the spacer yarn is fed by a feeding device, and the feeding device is located between the chassis and the collecting device of the hexagonal three-dimensional braiding machine;

[0028] The feeding device comprises a supporting base, two slide rails, a yarn feeding track, a shuttle, a first driving device and a second driving device;

[0029] The two slide rails are fixed on the support base, arranged vertically and spaced apart. The yarn feeding track is slidably connected to the two slide rails at the same time. The shuttle is slidably connected to the yarn feeding track. The first driving device is used to drive the shuttle to move horizontally along the yarn feeding track, and the second driving device is used to drive the yarn feeding track to move vertically along the two slide rails.

[0030] Beneficial effects:

[0031] (1) The present invention uses a hexagonal weaving chassis and a mechanism similar to the weft delivery in weaving to achieve the gradual addition of spacer yarns during the weaving process, thereby preparing a circular structured spacer fabric.

[0032] (2) The preparation method of the present invention is simple and easy to implement. By selecting the number of weaving units of the chassis and the distance between the diameter of the spacer fabric and the circular size, the thickness and diameter of the spacer fabric can be easily adjusted to meet different application requirements.

[0033] (3) The present invention can produce circular structure ultra-large spacing spacer fabrics that meet the needs of various application fields, thereby improving the application scope of circular structure three-dimensional spacer fabrics, especially in occasions requiring specific shapes and structures, such as high-end sports equipment, advanced medical equipment, and the automotive industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1A simplified schematic diagram of a production device for a circular structured three-dimensional spacer fabric (from a top view);

[0035] Figure 2 Weaving diagrams for linear tracks and tracks at corners;

[0036] Figure 3 This is a diagram of the interlacing pattern of spacer wire feeding;

[0037] Figure 4 It is a structural schematic diagram of the feeding device; wherein 4-support base, 5-first slide rail, 6-second slide rail, 7-yarn feeding track, 8-first driving device, 9-second driving device, 10-shuttle;

[0038] Figure 5 It is a schematic diagram of the structure of a circular three-dimensional spacer fabric, a corresponds to Example 1, b corresponds to Example 2, and c corresponds to Example 3; wherein 1-inner braided tube, 2-outer braided tube, 3-parallel spacer wire;

[0039] Figure 6 It is a three-dimensional schematic diagram of the production equipment of circular structure three-dimensional spacer fabric. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0041] The production equipment of the circular structure three-dimensional spacer fabric in the following embodiments is as follows Figure 1 and Figure 6 As shown, it includes a hexagonal three-dimensional braiding machine, a feeding device and a collecting device, and the feeding device is located between the chassis of the hexagonal three-dimensional braiding machine and the collecting device;

[0042] like Figure 1 As shown, the yarn carriers in the hexagonal three-dimensional braiding machine are distributed in four layers, and the layer numbers increase from the inside to the outside. The yarn carrier b is the yarn carrier of the first layer, and the yarn carrier a is the yarn carrier of the third layer.

[0043] like Figure 4As shown, the feeding device includes a supporting base 4, a first slide rail 5, a second slide rail 6, a yarn feeding track 7, a shuttle 10, a first driving device 8 and a second driving device 9; the first slide rail 5 and the second slide rail 6 are fixed on the supporting base 4, arranged vertically and arranged at intervals, the yarn feeding track 7 is slidably connected to the first slide rail 5 and the second slide rail 6 at the same time, the shuttle 10 is slidably connected to the yarn feeding track 7, the first driving device 8 is used to drive the shuttle 10 to move horizontally along the yarn feeding track 7, and the second driving device 9 is used to drive the yarn feeding track 7 to move vertically along the first slide rail 5 and the second slide rail 6;

[0044] When the feeding device is used to feed the spacer yarn, the first drive device 8 is started first, and the spacer yarn is horizontally moved along the yarn feeding track 7 toward the second drive device 9 under the drive of the shuttle 10, and the spacer yarn is guided to the predetermined position where each pair of interweaving points a and b are about to be formed. As the weaving process continues, the yarn carrier a and the yarn carrier b respectively drive the yarn a and the yarn b to interweave, and form a pair of interweaving points a and b at the predetermined position, thereby "sandwiching" (i.e. fixing) the spacer yarn between the two; when a new pair of interweaving points a and b is to be formed directly below the pair of interweaving points a and b to feed the spacer yarn, the second drive device 9 is started, and the position of the yarn feeding track 7 in the vertical direction is adjusted, so that the shuttle 10 can guide the spacer yarn to the position where a new pair of interweaving points a and b are about to be formed.

[0045] In the following embodiments, the interweaving of yarn a and yarn b is described by taking the third layer of a hexagonal three-dimensional braiding machine as an example. Figure 2 As shown:

[0046] (1) Linear track weaving:

[0047] (1.1) Cam No. 2 rotates 180° clockwise, so that yarn carrier No. 1 and yarn carrier No. 2 exchange positions;

[0048] (1.2) Cam No. 3 rotates 180° counterclockwise, so that cam No. 1 and cam No. 3 exchange positions. At this time, yarn a and yarn b are interwoven.

[0049] (2) Track weaving at corners;

[0050] (2.1) Cam No. 2 rotates 120° clockwise to move yarn carrier No. 2 to the starting position of yarn carrier No. 1, and then transfers yarn a and yarn b to cam No. 4;

[0051] (2.2) Cam No. 3 rotates 60° clockwise, and Cam No. 4 rotates 60° counterclockwise, transferring yarn a and yarn b to Cam No. 5;

[0052] (2.3) Cam No. 5 rotates 120° counterclockwise, and then transfers yarn a and yarn b back to Cam No. 3. Cam No. 3 rotates 60° counterclockwise, and finally sends yarn a and yarn b back to the starting position of yarn carrier No. 2. At this time, the yarns are interwoven;

[0053] The interlacing rule of spacer wire feeding is as follows Figure 3 shown.

[0054] Example 1

[0055] A preparation method of a circular structure three-dimensional spacer fabric, the specific steps are: controlling a yarn carrier a to rotate around a vertical virtual axis, driving a group of yarns a to interweave, synchronously controlling a yarn carrier b to rotate around the virtual axis, driving a group of yarns b to interweave, when the yarn carrier a and the yarn carrier b rotate around the virtual axis for one circle, the yarn a completes multiple interweaving to form m interweaving points a, and the yarn b completes multiple interweaving to form m interweaving points b, m is a positive integer;

[0056] The m interlacing points a are numbered from 1 to m in the order of appearance, and the m interlacing points b are numbered from 1 to m in the order of appearance, and the i-th interlacing point a and the i-th interlacing point b form a pair of interlacing points a and b for inserting spacer wires, i=1,…,m;

[0057] For each pair of interweaving points a and b, a spacer wire is inserted between the two through a feeding device when they are first formed, and then weaving is continued. When a new pair of interweaving points a and b is formed directly below the pair of interweaving points a and b, the spacer wire is inserted between the latest pair of interweaving points a and b through the feeding device. The process is repeated until the weaving is completed, and a circular structure three-dimensional spacer fabric is obtained.

[0058] like Figure 5 As shown in a, the final circular structure three-dimensional spacer fabric is composed of an inner braided tube 1 (woven from yarn b), an outer braided tube 2 (woven from yarn a) and parallel spacer wires 3 located between the two; the thickness of the circular structure three-dimensional spacer fabric exceeds 100 mm.

[0059] Example 2

[0060] A preparation method of a circular structure three-dimensional spacer fabric, the specific steps are: controlling a yarn carrier a to rotate around a vertical virtual axis, driving a group of yarns a to interweave, synchronously controlling a yarn carrier b to rotate around the virtual axis, driving a group of yarns b to interweave, when the yarn carrier a and the yarn carrier b rotate around the virtual axis for one circle, the yarn a completes multiple interweaving to form m interweaving points a, and the yarn b completes multiple interweaving to form m interweaving points b, m is a positive integer;

[0061] The m interweaving points a are numbered from 1 to m in the order of appearance, the m interweaving points b are numbered from 1 to m in the order of appearance, the j+1th interweaving point a and the jth interweaving point b form a pair of interweaving points a and b for inserting spacer wires, and at the same time, form a pair of interweaving points a and b for inserting spacer wires with the j+2th interweaving point b, the j+1th interweaving point b and the jth interweaving point a form a pair of interweaving points a and b for inserting spacer wires, and at the same time, form a pair of interweaving points a and b for inserting spacer wires with the j+2th interweaving point a, j=1,…,m-2;

[0062] For each pair of interweaving points a and b, a spacer wire is inserted between the two through a feeding device when they are first formed, and then weaving is continued. When a new pair of interweaving points a and b is formed directly below the pair of interweaving points a and b, the spacer wire is inserted between the latest pair of interweaving points a and b through the feeding device. The process is repeated until the weaving is completed, and a circular structure three-dimensional spacer fabric is obtained.

[0063] like Figure 5 As shown in b, the finally obtained circular structure three-dimensional spacer fabric is composed of an inner braided tube, an outer braided tube and a cross-type spacer wire located between the inner braided tube and the outer braided tube; the thickness of the circular structure three-dimensional spacer fabric exceeds 100 mm.

[0064] Example 3

[0065] A preparation method of a circular structure three-dimensional spacer fabric, the specific steps are: controlling a yarn carrier a to rotate around a vertical virtual axis, driving a group of yarns a to interweave, synchronously controlling a yarn carrier b to rotate around the virtual axis, driving a group of yarns b to interweave, when the yarn carrier a and the yarn carrier b rotate around the virtual axis for one circle, the yarn a completes multiple interweaving to form m interweaving points a, and the yarn b completes multiple interweaving to form m interweaving points b, m is a positive integer;

[0066] The m interweaving points a are numbered from 1 to m in the order of appearance, and the m interweaving points b are numbered from 1 to m in the order of appearance, the i-th interweaving point a and the i-th interweaving point b form a pair of interweaving points a and b for inserting spacer wires, i=1,…,m, at the same time, the j+1-th interweaving point a and the j-th interweaving point b form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2-th interweaving point b, the j+1-th interweaving point b and the j-th interweaving point a form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2-th interweaving point a, j=1,…,m-2;

[0067] For each pair of interweaving points a and b, a spacer wire is inserted between the two through a feeding device when they are first formed, and then weaving is continued. When a new pair of interweaving points a and b is formed directly below the pair of interweaving points a and b, the spacer wire is inserted between the latest pair of interweaving points a and b through the feeding device. The process is repeated until the weaving is completed, and a circular structure three-dimensional spacer fabric is obtained.

[0068] like Figure 5 As shown in c, the finally obtained circular structure three-dimensional spacer fabric is composed of an inner braided tube, an outer braided tube and a composite spacer wire located between the inner braided tube and the outer braided tube; the thickness of the circular structure three-dimensional spacer fabric exceeds 100 mm.

Claims

1. A method for preparing a circular structure three-dimensional spacer fabric, characterized in that: A group of yarns a is used to weave an outer braided tube, and a group of yarns b is used to weave an inner braided tube simultaneously. The outer braided tube is sleeved on the inner braided tube and the inner diameter of the outer braided tube is larger than the outer diameter of the inner braided tube. During the weaving process, multiple spacer wires are inserted between the interlacing points formed by the yarns a and the interlacing points formed by the yarns b. As the weaving process proceeds, the spacer wires are repeatedly inserted, and a circular structure three-dimensional spacer fabric is obtained after the weaving is completed.

2. The method for preparing a circular structure three-dimensional spacer fabric according to claim 1, characterized in that: The specific process is: controlling a group of yarn carriers a distributed in a ring shape to rotate around a vertical virtual axis, driving a group of yarns a to be interlaced, and synchronously controlling a group of yarn carriers b distributed in a ring shape and located inside the yarn carriers a to rotate around the virtual axis, driving a group of yarns b to be interlaced; When the yarn carrier a and the yarn carrier b rotate one circle around the virtual axis, the yarn a completes multiple interweaving to form m interweaving points a, and the yarn b completes multiple interweaving to form m interweaving points b, and the m interweaving points a are arranged at intervals from the m interweaving points b, where m is a positive integer; Select n interweaving points a and n interweaving points b from m interweaving points a and m interweaving points b respectively to form multiple pairs of interweaving points a and interweaving points b. For each pair of interweaving points a and interweaving points b, insert a spacer wire between the two when they are first formed, and then continue weaving. After at least one new pair of interweaving points a and interweaving points b is formed directly below the pair of interweaving points a and interweaving points b, insert the spacer wire between the latest pair of interweaving points a and interweaving points b, and repeat the process until the weaving is completed.

3. The method for preparing a circular structure three-dimensional spacer fabric according to claim 2, characterized in that: The n interlacing points a are numbered from 1 to n in the order of appearance, and the n interlacing points b are numbered from 1 to n in the order of appearance. The i-th interlacing point a and the i-th interlacing point b form a pair of interlacing points a and b for inserting spacer wires, i=1,…,n.

4. The method for preparing a circular structure three-dimensional spacer fabric according to claim 2, characterized in that: The n interweaving points a are numbered from 1 to n in the order of appearance, and the n interweaving points b are numbered from 1 to n in the order of appearance. The j+1th interweaving point a and the jth interweaving point b form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2th interweaving point b. The j+1th interweaving point b and the jth interweaving point a form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2th interweaving point a, j=1,…,n-2.

5. The method for preparing a circular structure three-dimensional spacer fabric according to claim 2, characterized in that: The n interweaving points a are numbered from 1 to n in the order of appearance, and the n interweaving points b are numbered from 1 to n in the order of appearance. The i-th interweaving point a and the i-th interweaving point b form a pair of interweaving points a and b for inserting spacer wires, i=1,…,n. At the same time, the j+1-th interweaving point a and the j-th interweaving point b form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2-th interweaving point b. The j+1-th interweaving point b and the j-th interweaving point a form a pair of interweaving points a and b for inserting spacer wires, and at the same time, they form a pair of interweaving points a and b for inserting spacer wires with the j+2-th interweaving point a, j=1,…,n-2.

6. The method for preparing a circular structure three-dimensional spacer fabric according to claim 2, characterized in that: n=m.

7. The method for preparing a circular structure three-dimensional spacer fabric according to claim 2, characterized in that: A hexagonal three-dimensional braiding machine is used. The yarn carriers in the hexagonal three-dimensional braiding machine are distributed in r layers. The layer numbers increase from the inside to the outside. The yarn carrier b is the yarn carrier of the r1th layer, and the yarn carrier a is the yarn carrier of the r2th layer. 3≤r1 <r2≤m。 8. The method for preparing a circular structure three-dimensional spacer fabric according to claim 7, characterized in that: The difference between r2 and r1 is not less than 2; the thickness of the circular structure three-dimensional spacer fabric exceeds 100mm.

9. The method for preparing a circular structure three-dimensional spacer fabric according to claim 8, characterized in that: The spacer yarn is fed by a feeding device, which is located between the chassis and the collecting device of the hexagonal three-dimensional braiding machine; The feeding device comprises a supporting base, two slide rails, a yarn feeding track, a shuttle, a first driving device and a second driving device; The two slide rails are fixed on the support base, arranged vertically and spaced apart. The yarn feeding track is slidably connected to the two slide rails at the same time. The shuttle is slidably connected to the yarn feeding track. The first driving device is used to drive the shuttle to move horizontally along the yarn feeding track, and the second driving device is used to drive the yarn feeding track to move vertically along the two slide rails.

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