阅读说明：本技术 一种符合人体脊柱自然生理曲度的座椅椅背及其制备方法 (Chair back conforming to natural physiological curvature of human spine and preparation method thereof ) 是由 王丽丽 王山水 郁秀峰 魏存宏 袁亮 张玉梅 于 2020-12-11 设计创作，主要内容包括：本发明涉及一种符合人体脊柱自然生理曲度的座椅椅背及其制备方法,座椅椅背主要由若干层椅背增强织物和热固性环氧树脂组成；椅背增强织物是由经纱和纬纱交织即形成的且与人体背部的曲面形状一致的单层平纹机织物；单层平纹机织物上的所有经纱与任一呈弯曲状的经纱所在的平面平行；单层平纹机织物上的所有纬纱与任一呈弯曲状的纬纱所在的平面平行；单层平纹机织物上各处的经密相同,纬密相同；制备方法：采用平纹织造工艺,制得椅背增强织物,再采用树脂转移模塑成形工艺制得毛坯件,将椅背增强织物叠放于预成型毛坯件上,以热固性环氧树脂进行加工,制得座椅椅背；本发明的一种符合人体脊柱自然生理曲度的座椅椅背,保证了舒适性、健康。(The invention relates to a chair back conforming to the natural physiological curvature of a spine of a human body and a preparation method thereof, wherein the chair back mainly comprises a plurality of layers of chair back reinforced fabrics and thermosetting epoxy resin; the chair back reinforced fabric is a single-layer plain woven fabric which is formed by interweaving warp yarns and weft yarns and has the same curved surface shape with the back of a human body; all warps on the single-layer plain woven fabric are parallel to the plane of any bent warp; all weft yarns on the single-layer plain woven fabric are parallel to the plane where any one bent weft yarn is located; the warp density and the weft density of each part of the single-layer plain woven fabric are the same; the preparation method comprises the following steps: preparing a chair back reinforced fabric by adopting a plain weaving process, preparing a blank by adopting a resin transfer molding forming process, stacking the chair back reinforced fabric on the preformed blank, and processing by using thermosetting epoxy resin to prepare the chair back; the chair back conforming to the natural physiological curvature of the spine of the human body ensures comfort and health.)

1. A chair back conforming to the natural physiological curvature of the spine of a human body is characterized in that the shape of a curved surface presented on the front side of the chair back is consistent with the shape of a curved surface on the back of the human body; the chair back mainly comprises a plurality of layers of chair back reinforced fabrics and thermosetting epoxy resin;

the chair back reinforced fabric is a single-layer plain woven fabric formed by interweaving warps and wefts, and the shape of the single-layer plain woven fabric is consistent with that of the curved surface of the back of a human body;

all warps on the single-layer plain woven fabric are parallel to the plane of any bent warp; all weft yarns on the single-layer plain woven fabric are parallel to the plane where any one bent weft yarn is located; the warp density and the weft density of each part of the single-layer plain woven fabric are the same;

in the chair back, the content of the chair back reinforced fabric is 65-70 wt%.

2. The chair back according to claim 1, wherein the warp density λ of the single layer plain woven fabric is_{Warp beam}60 to 155 pieces/10 cm, weft density lambda_{Weft yarn}60-155 roots/10 cm; the number of layers is 1-3; warp yarns and weft yarns are polyester industrial yarns, the fineness of the polyester industrial yarns is 1000-2500 dtex, the breaking strength is 7.0-7.5 cN/dtex, and the elongation at break is 10-15%.

3. The chair back according to the natural physiological curvature of the spine of the human body as claimed in claim 2, wherein the fit coefficient of the back reinforcing fabric is more than 98.5%.

4. A method for preparing a chair back according to any one of claims 1 to 3, wherein the method comprises the following steps:

(1) adopting a plain weaving process, arranging a chair back reinforced fabric weaving area, and forming each weave point according to the heddle eye height h of the weave point formed by the ith weft yarn and the jth warp yarn corresponding to the curved surface of the back of a human body_ijPreparing the chair back reinforced fabric;

when the chair back reinforced fabric is woven, a grid-shaped support body with the surface presenting the same curved surface of the back of a human body is placed in the area from the corresponding weaving opening to the first row of heddles; the grid-shaped support body is formed by connecting a plurality of thin plates which are arranged at equal intervals, the thickness direction of the thin plates is the same as the weft yarn direction, the interval between every two adjacent thin plates is the interval between every two adjacent dents of the reed, and the thickness of each thin plate is 1/3 smaller than the interval between every two adjacent dents of the reed;

when the chair back reinforced fabric is woven, each warp yarn is independently and passively let-off under constant tension;

(2) the method comprises the steps of preparing a preformed blank according to the curved surface of the back of a human body by adopting a resin transfer molding process, sequentially stacking a plurality of layers of chair back reinforcing fabrics on the preformed blank, processing by taking thermosetting epoxy resin as a main raw material, and finishing to obtain the chair back.

5. The preparation method of the chair back conforming to the natural physiological curvature of the spine of the human body according to claim 4, wherein the raw materials in the step (2) further comprise a curing agent, and the mass ratio of the thermosetting epoxy resin to the curing agent is 80-90: 15-20.

6. The method for preparing the chair back according with the natural physiological curvature of the spine of the human body according to claim 4, wherein in the weaving method of the chair back reinforced fabric, each tissue point is formed before weft insertion, after weft insertion or after beating up; the thin plate is made of metal;

the tension of the warp yarns is 50-70 cN/warp yarn; the tension of the weft yarn is 30-40 cN/root;

the winding speed is 1.1-5.3 cm/min, and the beating-up speed is 16-18 pieces/min.

7. The method for preparing a chair back according to the natural physiological curvature of the spine of a human body as claimed in claim 6, wherein when each tissue point is formed, the horizontal distance from the tissue point to the heddle eyes of the first row of heddles is set to be 2-5 times of the height of the lifting heddle.

8. The method for preparing a chair back according with the natural physiological curvature of the spine of a human body as claimed in claim 4, wherein the passive let-off is realized by a torsion spring type tension adjusting device.

Technical Field

The invention belongs to the technical field of office furniture, and relates to a chair back conforming to the natural physiological curvature of a spine of a human body and a preparation method thereof.

Background

In sitting posture work, the functional structure, the size and the shape of each part of the human body are directly related to the seat, even the perception, the thinking and the like of the human body form a direct or indirect contact relation with the seat to some extent, and the relation is called an interface relation. Comfortable seat designs must meet the comfort of human chair interface designs, i.e., provide a human-chair interface that meets the physiological and psychological needs of the human body. The human-chair interface design is mainly from the following 4 aspects: the functional dimensions of the seat, the shape of the human-chair interface, the material of the seat, the activity of the human-chair interface have an influence on the comfort of the seat.

The human-chair interface shape design mainly focuses on two aspects of the backrest shape design and the seat surface shape design. When a human body contacts with the backrest and the seat surface of the seat, the pressure distribution of the human body acting on the seat mainly comprises 2 parts of backrest pressure distribution and seat surface pressure distribution, and the relationship between the human-chair interface form and the comfort can be obtained through the measurement of the pressure distribution. The relationship between the seat curved surface form (the concave-convex degree of the backrest and seat surface curved surfaces) and the comfort is analyzed and researched by using a body pressure distribution test method, so that the seat curved surface which maximizes the comfort and accords with the natural physiological curvature of the spine of a human body can be obtained. Meanwhile, in the research of the relationship between the human body spine health and the shape comfort of the chair back of the office chair, the chair back designed according to the optimal arc trend of the human body can enable the spine to be in the optimal state when the human body leans against the chair back, so that the comfort is guaranteed, and the health of the human body spine is met. The shape design of the seat surface and the backrest of the seat can obviously influence the comfort level of a human body, and only by establishing the relation between the surface shapes of the contact part of the seat and the human body, the curved surface shape of the seat which is more accurate and reasonable can be obtained, so that the comfort level of the human body is improved.

Composite materials are one of the common materials for seats, and are relatively lightweight. In visual sense, the composite material has better toughness than metal, moderate surface smoothness and wide application in daily life. However, at present, when the composite material is applied to the chair back, fabric is rarely used as the reinforcement, even if the composite material is used, the 2D fabric can only be used as the reinforcement, and the 2D fabric can only be cut and spliced into the curved surface shape of the chair back when being used as the reinforcement of the chair back, which is not only troublesome, but also greatly increases the splicing difficulty because different back curved surfaces are different. In addition, the composite material supported by the splicing structure has the following problems: not beautiful enough and is easy to deform under stress when a person leans against.

Disclosure of Invention

The invention aims to solve the problems that the prior art is not beautiful enough and is easy to deform under stress when a person leans against the chair for a long time, and provides a chair back conforming to the natural physiological curvature of the spine of the human body and a preparation method thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a chair back conforming to the natural physiological curvature of the spine of a human body, the shape of a curved surface presented by the front surface (namely the surface directly contacted with the back of the human body) of the chair back is consistent with the shape of the curved surface of the back of the human body; the chair back mainly comprises a plurality of layers of chair back reinforced fabrics and thermosetting epoxy resin;

the chair back reinforced fabric is a single-layer plain woven fabric formed by interweaving warps and wefts, and the shape of the single-layer plain woven fabric is consistent with that of the curved surface of the back of a human body;

all warps on the single-layer plain woven fabric are parallel to the plane of any bent warp; all weft yarns on the single-layer plain woven fabric are parallel to the plane where any one bent weft yarn is located; the warp density and the weft density of each part of the single-layer plain woven fabric are the same;

in the chair back, the content of the chair back reinforced fabric is 65-70 wt%.

As a preferred technical scheme:

the warp density lambda of the single-layer plain woven fabric (namely the chair back reinforced fabric) of the chair back conforming to the natural physiological curvature of the spine of the human body_{Warp beam}60 to 155 pieces/10 cm, weft density lambda_{Weft yarn}60-155 roots/10 cm; the larger the titer of the yarn is, the smaller the corresponding warp density or weft density is; warp yarns and weft yarns are polyester industrial yarns, the titer of the polyester industrial yarns is 1000-2500 dtex, the breaking strength is 7.0-7.5 cN/dtex, and the elongation at break is 10-15%; the number of layers is 1-3.

According to the chair back conforming to the natural physiological curvature of the spine of the human body, the fit coefficient of the chair back reinforced fabric is more than 98.5%.

The invention also provides a method for preparing the chair back conforming to the natural physiological curvature of the spine of the human body, which comprises the following steps:

(1) adopting a plain weaving process, arranging a chair back reinforced fabric weaving area, and forming each weave point in the chair back reinforced fabric weaving area according to the heddle eye height h of the weave point formed by the ith weft yarn and the jth warp yarn corresponding to the curved surface of the back of a human body_ijAnd a single-layer plain woven fabric (woven by adopting a plane woven fabric weaving process in the prior art) is arranged around the weaving area (about 10cm distance) of the chair back reinforced fabric as a transition, and after weaving is finished, the plain woven fabric is wovenCutting off the single-layer plain weave machine fabric to prepare the chair back reinforced fabric;

when the chair back reinforced fabric is woven, a grid-shaped support body with the surface presenting the same curved surface of the back of a human body is placed in the area from the corresponding weaving opening to the first row of heddles; the grid-shaped support body is formed by connecting a plurality of thin plates which are arranged at equal intervals, the thickness direction of the thin plates is the same as the weft yarn direction, the interval between every two adjacent thin plates is the interval between every two adjacent dents of the reed, and the thickness of each thin plate is 1/3 smaller than the interval between every two adjacent dents of the reed; the number of the plurality of thin plates can be calculated according to the distance between the adjacent thin plates and the thickness of the thin plates and the width of the whole grid-shaped support body.

During weaving of the chair back reinforcement fabric, each warp yarn is independently driven to warp under constant tension.

When the introduced weft yarns are punched into the weaving opening by the reed, the weft yarns are distributed along the upper surface of the supporting body one by one and can support the warp yarns to ensure the stability of the shape of the woven curved surface.

(2) The method comprises the steps of preparing a preformed blank (namely a mold) according to a curved surface of the back of a human body by adopting a resin transfer molding forming process, sequentially stacking a plurality of layers of chair back reinforcing fabrics on the preformed blank, processing by taking thermosetting epoxy resin as a main raw material, sequentially sealing, vacuumizing, injecting resin, curing, demolding and finishing to obtain the chair back.

As a preferred technical scheme:

according to the preparation method of the chair back conforming to the natural physiological curvature of the spine of the human body, the raw materials in the step (2) also contain a curing agent, and the mass ratio of the thermosetting epoxy resin (cyanuric acid epoxy resin) to the curing agent (diethylaminopropylamine) is 80-90: 15-20.

According to the preparation method of the chair back conforming to the natural physiological curvature of the spine of the human body, in the weaving method of the chair back reinforced fabric, when each tissue point is formed, the tissue point refers to before weft insertion, after weft insertion or after beating-up; the thin plate is made of metal;

the tension of the warp yarns is 50-70 cN/warp yarn; the tension of the weft yarn is 30-40 cN/root;

the winding speed is 1.1-5.3 cm/min, and the beating-up speed is 16-18 pieces/min; the height of the heddle eye of the heddle corresponding to each warp yarn is adjusted before each beating-up, and the heddle is controlled to lift by a certain height by independently connecting different heddles with different lifting mechanisms.

According to the preparation method of the chair back conforming to the natural physiological curvature of the spine of the human body, when each tissue point is formed, the horizontal distance from the tissue point to the heddle eyes of the first row of heddles is set to be 2-5 times of the height of the lifting heddle; the height of the lifting heddle is the height of the heddle eyes of the first row of heddles compared with the horizontal plane of the weft yarn during weft insertion.

According to the preparation method of the chair back conforming to the natural physiological curvature of the spine of the human body, passive let-off refers to the adoption of a torsion spring type tension adjusting device. The package of warp yarns is placed on a creel, and the yarn drawn from each bobbin is provided with a torsion spring type tension adjusting device, and the tension of each warp yarn in the let-off process is kept constant.

The mechanism of the invention is as follows:

in the prior art, compared with a two-dimensional fabric, the three-dimensional fabric does not need to be cut and sewn during composite forming, the integrity of the fabric is improved, the composite forming process is simplified, and the prepared chair back reinforced fabric has great superiority in the integral delamination resistance, impact resistance and fatigue resistance compared with a two-dimensional woven fabric composite material.

Compared with the integrally formed three-dimensional fabric in the prior art, the plane of the weft yarn in the three-dimensional curved surface area is not parallel to each other on the integrally formed three-dimensional fabric in the prior art, and the fabric integrally presents uneven warp density and weft density in different areas, so that the uneven fabric structure can cause uneven stress on each area when the fabric is stressed; on the basis that all the warp yarns are parallel to the plane where the warp yarns of the three-dimensional curved surface area are located and all the weft yarns are parallel to the plane where the weft yarns of the three-dimensional curved surface area are located, the warp and weft densities in all the areas are uniform, and the uniform stress of the integrally-formed three-dimensional fabric is guaranteed.

In order to prepare the three-dimensional fabric, the grid-shaped support body is adopted to weave the three-dimensional fabric, and compared with a special-shaped roller reeling method, in the weaving process of the special-shaped roller reeling method, the linear speed at the small end area of the special-shaped roller is smaller than the linear speed at the large end area of the special-shaped roller, so that the density of weft yarns at the small end area of the special-shaped roller is greater than that at the large end area of the special-shaped roller, and the density of weft yarns of the three-dimensional fabric prepared by the special-shaped roller reeling; the grid-shaped support body adopted by the invention is formed by arranging and combining a plurality of plane sheets at equal intervals, when in weaving, the thickness direction of the sheets is the same as the weft yarn direction, the sheets can smoothly enter between reed dents, the interval between the adjacent sheets is the interval between the adjacent reed dents of the reed, and the thickness of each sheet is smaller than 1/3 of the interval between the adjacent reed dents of the reed, so that the existence of the sheets does not influence the interweaving of yarns, the weft yarns can be arranged at equal intervals when in beating, the weft yarns are linear in the projection direction of the prepared fabric, and when in winding at a constant speed, the density of the weft yarns is uniform; the warp density is controlled by a reed, and the warp density can be ensured to be consistent by a conventional reed and a standard drafting process.

Moreover, when weaving the curved surface area of the three-dimensional fabric, according to the form of the curved surface area, through the control of the height of the heddle eyes, the warp feeding amount increment of the warp yarn in the curved surface area with different heights is different, and the general principle is as follows: the height of the heddle eyes penetrated by the warp yarns which participate in the weaving of the upper area of the curved surface area is higher than that of the heddle eyes penetrated by the warp yarns which participate in the weaving of the lower area of the curved surface area; the heights of the front beam and the back beam are consistent and are kept unchanged in the weaving process, when the height of a brown eye, corresponding to the height of the front beam or the back beam, of the warp yarn is 0 when the warp yarn is returned to the heald flat position, the warp yarn and the weft yarn are interwoven to form a plane area, and when the height of the brown eye, corresponding to the height of the front beam or the back beam, of the warp yarn is not 0 when the warp yarn is returned to the heald flat position, the warp yarn and the weft yarn are interwoven to form a curved surface area.

Meanwhile, the curved fabric prepared by the grid method has better fitting degree with the designed shape, the grid-shaped support body does not need to carry out optimization in the previous design and detection and correction of the fitting degree in the later period, the excellent fitting effect can be realized, and the variety can be changed more quickly.

In addition, the grid-shaped support body adopted in the method is simple to prepare, and the special-shaped roll curling method is used for preparing the three-dimensional fabric, and the special-shaped roll corresponding to the action of the grid-shaped support body is in a three-dimensional shape, so that the processing is very complex.

In the weaving process of the chair back reinforced fabric, the let-off of the chair back reinforced fabric is suitable for passive let-off, because the shedding height difference of each warp yarn of the three-dimensional fabric with small curvature is small during weaving, the warp yarn with high shedding height can not exceed the length adjusting space of a tension device (namely, under constant tension) in a passive let-off system because of being excessively pulled out, the process is simple, and the application range is wide.

The purpose of passive let-off is to ensure that let-off quantity and tension are controllable and accurate, so as to ensure that the density of the woven three-dimensional fabric is uniform, and the technical requirement on the fit coefficient is realized under the supporting action of the grid-shaped supporting body.

The reinforcement in the chair back of the chair prepared by the invention is the integrally formed chair back reinforcement fabric (three-dimensional fabric), and because the density of the three-dimensional fabric is uniform, the stress is uniform when the three-dimensional fabric is stressed, and the fit coefficient of the three-dimensional fabric is high, and the interlayer difference can not be generated when the three-dimensional fabric is compounded layer by layer, compared with the splicing reinforcement, the mechanical property is better, and when people lean against for a long time, the three-dimensional fabric is supported by the layers, the deformation is not easy to generate, and the comfort of the chair back can be kept for a long time. Moreover, the polyester industrial yarn adopted by the invention is of an integrated structure, conforms to the back curve of a human body, and is very attractive and unique to individuals.

Advantageous effects

(1) According to the preparation method of the chair back conforming to the natural physiological curvature of the spine of the human body, the warp yarns and the weft yarns can be interwoven on the curved surface by controlling the lifting stroke, and the chair back reinforced fabric with a specific curved surface form can be prepared;

(2) the invention relates to a preparation method of a chair back conforming to the natural physiological curvature of the spine of a human body, which is characterized in that polyester industrial yarns are used as basic reinforcing materials, and thermosetting epoxy resin composite materials are molded by adopting an integral structure formed by one-time compression molding, so that the chair back has the advantages of high strength, light specific gravity, low price, long service life and the like;

(3) according to the chair back conforming to the natural physiological curvature of the spine of the human body, the chair back designed according to the optimal arc trend of the human body can enable the spine to be in the optimal state when the human body leans against the chair back, so that the comfort is ensured, and the health of the spine of the human body is met.

Drawings

FIG. 1 is a side view profile of a human spine and a profile of a human back;

FIG. 2 is a graph;

FIG. 3 is a curved view of the back of a human body;

fig. 4 is a spatial lattice diagram.

Detailed Description

The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

A preparation method of a chair back conforming to the natural physiological curvature of a human spine comprises the following specific steps:

(1) firstly, preparing raw materials:

warp yarn: the fineness of the polyester industrial yarn is 2200dtex, the breaking strength is 7.3cN/dtex, and the elongation at break is 11%;

weft yarn: the fineness of the polyester industrial yarn is 2200dtex, the breaking strength is 7.3cN/dtex, and the elongation at break is 11%;

(2) adopting a plain weaving process, arranging a chair back reinforced fabric weaving area, and forming each weave point (after beating up) according to the heddle eye height h of the weave point formed by the ith weft yarn and the jth warp yarn corresponding to the back curved surface of a human body_ijArranging a single-layer plain woven fabric (woven by adopting a plane woven fabric weaving process in the prior art) around the weaving area (about 10cm distance) of the chair back reinforced fabric as a transition, cutting off the single-layer plain woven fabric after weaving is finished, and preparing the chair back reinforced fabric;

when the chair back reinforced fabric is woven, a grid-shaped support body with the surface presenting the same curved surface of the back of a human body is placed in a weaving opening corresponding to a chair back reinforced fabric weaving area to a first row of harness wire area; the grid-shaped supporting body is formed by connecting a plurality of metal sheets which are arranged at equal intervals, the thickness direction of the metal sheets is the same as the weft yarn direction, the interval between every two adjacent metal sheets is the interval between every two adjacent reed dents of the reed, and the thickness of each metal sheet is 1/3 smaller than the interval between every two adjacent reed dents of the reed;

when the chair back reinforced fabric is woven, a torsion spring type tension adjusting device is adopted to independently and passively send warp yarns under constant tension; the tension of the warp yarns is 55 cN/yarn; the tension of the weft yarn is 37 cN/root; the winding speed is 1.4cm/min, and the beating-up speed is 17 pieces/min; adjusting the height of a heddle eye of a heddle corresponding to each warp yarn before each beating-up, and controlling each heddle to ascend and descend by a certain height by independently connecting different heddles with different elevating mechanisms; when each tissue point is formed, setting the horizontal distance from the tissue point to the heddle eyes of the first row of heddles to be 4 times of the height of the lifting heddle;

the heddle eye height h of a weave point formed by the ith weft yarn and the jth warp yarn corresponding to the back curved surface of the human body_ijThe acquisition method comprises the following steps:

as shown in FIG. 1, in AutoCAD, a curve L is drawn in the vertical direction with reference to the profile of a side view of the human spine_VCurve L_VRespectively has an endpoint of P_OAnd P_ERespectively drawn in the horizontal direction according to the back contour of the human bodyCurve making L_TN curves L_MAnd curve L_BWherein, curve L_TN curves L_MAnd curve L_BAll relative to curve L_VThe planes are symmetrical, and the middle points are all positioned on the curve L_VUpper, curve L_TIs the midpoint of (1) as an endpoint P_OCurve L_BIs the midpoint of (1) as an endpoint P_E(ii) a Drawing the simultaneous curve L_VThe plane and the curve L_TA reference plane R perpendicular to the plane in which it lies; by curve L_VAs a guide line, a curve L is formed in sequence_TN curves L_MAnd curve L_BTaking the cross section line as a cross section line to obtain a human back curved surface (as shown in figures 2-3);

a right-hand spatial rectangular coordinate system oxyz (user coordinate system UCS) as shown in fig. 4 is established on the reference plane R, the coordinate system xoy plane coinciding with the plane R. Plotting the ox-direction spacing Δ wx and the oy-direction spacing Δ w on the reference plane R (or any plane parallel to R)_yThen the lattice is projected onto the curved surface along the oz direction to obtain a spatial lattice (as shown in fig. 4). Then, in the space lattice, a point P is located in the ith row from the ox direction and the jth column from the oy direction (i, j are positive integers)_ijThe coordinate in the oxyz system is (i Δ w)_x，jΔw_y，h_ij). Wherein h is_ijCan be obtained by subtracting the same reading corresponding to the coordinate origin o from the reading in the WCS of a certain coordinate value (possibly one of x, y and z coordinates, depending on the relative position of UCS and the world coordinate WCS of AutoCAD) of P;

specifically obtaining the heddle eye height h of a weave point formed by the ith weft yarn and the jth warp yarn_ij(cm), see tables 1-4 in sequence:

TABLE 1

TABLE 2

TABLE 3

TABLE 4

The prepared chair back reinforced fabric is a single-layer plain woven fabric which is formed by interweaving warp yarns and weft yarns and has the same shape with the curved surface of the back of a human body; all warp yarns on the single-layer plain woven fabric are parallel to a plane where any warp yarn in a bent shape is located, and all weft yarns are parallel to a plane where any weft yarn in a bent shape is located; and the warp density of each part of the single-layer plain woven fabric is the same, the weft density is the same and the warp density lambda is_{Warp beam}122 pieces/10 cm, weft density lambda_{Weft yarn}122 roots/10 cm; in the chair back, the content of the chair back reinforced fabric is 66 wt%, and the fit coefficient is 98.7%;

(3) the preparation method comprises the steps of preparing a preformed blank (namely a mold) according to a human back curved surface by adopting a resin transfer molding process, sequentially stacking 3 layers of chair back reinforcing fabrics on the preformed blank, processing by taking cyanuric acid epoxy resin and diethylaminopropylamine with a mass ratio of 88:16 as raw materials, sequentially sealing, vacuumizing, injecting resin, curing and demolding, and finishing to obtain the chair back.

According to the prepared chair back conforming to the natural physiological curvature of the spine of the human body, the curved surface shape presented by the front surface (namely the surface directly contacted with the back of the human body) of the chair back is consistent with the curved surface shape of the back of the human body; the chair back mainly comprises 3 layers of chair back reinforced fabric and thermosetting epoxy resin.