Police helmet made of composite material and preparation method thereof
阅读说明：本技术 一种复合材料制成的警用头盔及其制备方法 (Police helmet made of composite material and preparation method thereof ) 是由 王山水 孙晓华 尹立新 陈瑞 张玉梅 王丽丽 于 2020-12-11 设计创作，主要内容包括：本发明涉及一种复合材料制成的警用头盔及其制备方法,警用头盔是由若干层半浸渗芳纶复合材料预浸料组成；半浸渗芳纶复合材料预浸料由3D芳纶纤维平纹布与改性酚醛树脂组成；3D芳纶纤维平纹布是由经纱和纬纱交织即形成的单层平纹机织物；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,所有纬纱与任一呈弯曲状的纬纱所在的平面平行；且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,设定对应的综眼高度和送经量,制得3D芳纶纤维平纹布；与改性酚醛树脂复合,得到半浸渗芳纶复合材料预浸料,制成警用头盔；本发明采用的三维织物在复合成型时不需要裁剪缝合,简化复合成型工艺,同时有利于提高头盔的抗冲击性能。(The invention relates to a police helmet made of composite material and a preparation method thereof, wherein the police helmet is composed of a plurality of layers of semi-impregnated aramid fiber composite material prepreg; the semi-impregnated aramid composite prepreg consists of 3D aramid fiber plain cloth and modified phenolic resin; the 3D aramid fiber plain cloth is a single-layer plain woven fabric formed by interweaving warp yarns and weft yarns; 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; 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: setting corresponding heddle eye height and let-off quantity by adopting a plain weaving process to prepare 3D aramid fiber plain cloth; compounding with modified phenolic resin to obtain semi-impregnated aramid composite prepreg, and making into police helmet; the three-dimensional fabric adopted by the invention does not need to be cut and sewn during composite forming, simplifies the composite forming process and is beneficial to improving the shock resistance of the helmet.)
1. A police helmet made of composite materials is characterized in that: the prepreg is composed of a plurality of layers of semi-impregnated aramid fiber composite prepregs;
the semi-impregnated aramid composite prepreg consists of 3D aramid fiber plain cloth and modified phenolic resin;
the mass percent of the modified phenolic resin in the prepreg of the semi-impregnated aramid fiber composite material is 8-18%;
the 3D aramid fiber plain cloth is a single-layer plain woven fabric formed by interweaving warp yarns and weft yarns; the shape of the single-layer plain woven fabric consists of a spherical crown and an extension surface; the extension surface is formed by extending outwards along the plane where the bottom of the spherical crown is located; 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; 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.
2. A police helmet made of a composite material according to claim 1, wherein the radius R of the spherical cap is 8.5-11 cm, the height H of the spherical cap is 6-11 cm, and H is less than or equal to R;
warp density lambda of single layer plain woven fabricWarp beam70-165 pieces/10 cm, weft density lambdaWeft yarn70-165 roots/10 cm;
the warp yarns and the weft yarns are made of para-aramid fibers; the fineness of the warp yarn or weft yarn is 1000-2500 dtex, the breaking strength is 27.0-35.0 cN/dtex, and the elongation at break is 3.5-4.5%.
3. A police helmet made of a composite material according to claim 2, wherein the modified phenolic resin is 10-14% of the prepreg of the semi-impregnated aramid composite material in percentage by mass.
4. A police helmet made of a composite material according to claim 3, wherein the number of layers is 5-10, and the fit coefficient of the 3D aramid fiber plain cloth is more than 97.3%.
5. The police helmet made of the composite material according to claim 4, wherein the weight of the police helmet is 0.5-0.8 kg, the police helmet is high in penetration resistance, and the police helmet can bear the puncture of a steel cone of 3kg with the energy of 106J; after the police helmet laterally applies 450N pressure, the maximum deformation is less than 40mm, the residual deformation is less than 12mm, and the helmet shell does not fall off.
6. A method of making a police helmet comprising a composite material according to any one of claims 1 to 5, characterised in that: preparing a modified phenolic resin impregnation liquid according to a certain proportion, immersing 3D aramid fiber plain cloth in the impregnation liquid, taking out the impregnated aramid fiber plain cloth, airing the impregnated aramid fiber plain cloth at normal temperature until the mass content of volatile matter is less than 4% to obtain a semi-impregnated aramid composite prepreg, and finally preparing a police helmet by taking a plurality of layers of the semi-impregnated aramid composite prepreg as raw materials;
the preparation method of the modified phenolic resin comprises the following steps: mixing phenolic resin, a modifier and a release agent, adding a diluent, and uniformly stirring to obtain the phenolic resin modified release agent;
the weaving method of the 3D aramid fiber plain cloth comprises the following steps: adopting a plain weaving process, setting a weaving area of the 3D aramid fiber plain cloth, and setting corresponding heddle eye height and let-off quantity when each weave point is formed to prepare the 3D aramid fiber plain cloth;
in a 3D aramid fiber plain cloth weaving area, a calculation method of the heddle eye height and the let-off quantity comprises the following steps:
when (w)i-L/2)2+(vj-D/2)2≥R2When the temperature of the water is higher than the set temperature,
hij＝0，sij＝10/λweft yarn；
When (w)i-L/2)2+(vj-D/2)2＜R2When the temperature of the water is higher than the set temperature,
wi＝i×10/λweft yarn；
vj＝j×10/λWarp beam；
Wherein h isijThe heddle eye height s of a structure point formed by the ith weft yarn and the jth warp yarn when weaving a 3D aramid fiber plain cloth weaving areaijThe warp feeding amount of a weave point formed by an ith weft yarn and a jth warp yarn when a 3D aramid fiber plain cloth weaving area is woven is represented by i being 1,. m, j being 1,. n, m is the number of beating-up times, and n is the number of warp yarns; r is the radius of the spherical crown, H is the height of the spherical crown, L is the length of a 3D aramid fiber plain cloth weaving area along the warp direction, D is the width of the 3D aramid fiber plain cloth weaving area along the weft direction, and lambdaWeft yarnIs the weft density, lambda, of the 3D aramid fiber plain cloth weaving areaWarp beamThe warp density of a 3D aramid fiber plain cloth weaving area is measured; radian is used as a unit of angle;
when the 3D aramid fiber plain cloth is woven, placing a grid-shaped support body with the same spherical crown on the surface in the area from the corresponding cloth fell 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 3D aramid fiber plain cloth is woven, each warp yarn is independently and actively let-off under constant tension.
7. The preparation method of the police helmet made of the composite material according to claim 6, wherein in the preparation method of the modified phenolic resin impregnation liquid, the phenolic resin is S-157 phenolic resin with a solid content of 50-55%, the modifier is polyvinyl formal acetaldehyde, the release agent is oleic acid, and the diluent is ethanol; the mass ratio of the phenolic resin to the modifier to the release agent to the diluent is 60-70: 30-40: 1: 40-50.
8. A method for preparing a police helmet from a composite material according to claim 6, wherein the ratio is 180-190 g/m2。
9. A method for preparing a police helmet made of a composite material according to claim 6, wherein in the weaving method of the 3D aramid fiber plain cloth, before weft insertion, after weft insertion or after beating up is performed when each tissue point is formed; the thin plate is made of metal;
the independent active warp let-off of each warp yarn is realized by independently connecting different warp yarns with different warp let-off mechanisms and controlling the warp let-off amount of each warp yarn;
the tension of the warp yarns is 30-100 cN/piece; the tension of the weft yarn is 10-40 cN/root;
the winding speed is 1.4cm-2.6cm/min, and the beating-up speed is 10-18 pieces/min.
10. A method of forming a composite police helmet according to claim 9, wherein the horizontal distance from the point to the eye of the first row of heddles is 2 to 5 times the height of the lifting heddle.
Technical Field
The invention belongs to the technical field of protective equipment, and relates to a police helmet made of a composite material and a preparation method thereof.
Background
The anti-riot helmet is a protective device which is required to be worn by an individual soldier in the process of carrying out an anti-riot task, and is always regarded by military forces of various countries. The anti-riot helmet is mostly made of metal materials and is used for resisting attacks of sharp tools, sticks, non-explosive throws and chemical liquids, so that the head, the face and the neck of a human body are effectively protected.
At present, two types of common anti-riot helmets exist. The anti-riot helmet is composed of a metal layer helmet body and a high-strength fiber fabric layer helmet body arranged in the metal layer helmet body, is heavy and too high in rigidity, and not only can the activity of a wearer be limited, but also the action performance during task execution is seriously influenced. The other kind comprises the plastic layer and the high-strength fiber fabric layer helmet body of setting in the plastic layer helmet body, and the plastic layer helmet body and the high-strength fiber fabric layer helmet body laminating of this anti-riot helmet are inseparable enough, have certain space between the plastic layer helmet body and the high-strength fiber fabric layer helmet body, and the bulletproof performance of the helmet can be influenced undoubtedly to the existence in space, and there is the unevenness of certain density on the fiber fabric layer simultaneously, makes the anti-riot helmet very heavy, and the travelling comfort is low.
The aramid fiber has the characteristics of high strength, high modulus and the like, so the high-strength fiber fabric layer helmet body mostly adopts the aramid fiber fabric layer. The phenolic resin has excellent mechanical property, heat resistance and electric insulation property, and is high in forming speed and low in cost, thereby being an ideal thermosetting matrix resin.
Therefore, the development of a police helmet with uniform fiber fabric density and good fitting performance and a preparation method thereof are urgently needed.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a police helmet made of a composite material and a preparation method thereof. The 3D form of the 3D aramid fiber plain cloth in the police helmet is obtained by weaving and not by secondary processing, so that the defects of low interlaminar shear strength, easiness in layering damage, wrinkle and aerial appearance of a two-dimensional fabric during composite forming are effectively overcome.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a police helmet made of composite material is composed of a plurality of layers of semi-impregnated aramid fiber composite material prepreg;
the semi-impregnated aramid composite prepreg consists of 3D aramid fiber plain cloth and modified phenolic resin;
the mass percent of the modified phenolic resin in the prepreg of the semi-impregnated aramid fiber composite material is 8-18%;
the 3D aramid fiber plain cloth is a single-layer plain woven fabric formed by interweaving warp yarns and weft yarns; the shape of the single-layer plain woven fabric consists of a spherical crown and an extension surface; the extension surface is formed by extending outwards along the plane where the bottom of the spherical crown is located; 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; 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.
It should be noted that the shape referred to herein is a shape obtained by ignoring microscopic undulations of the woven fabric surface caused by the interweaving of warp and weft yarns.
As a preferred technical scheme:
according to the police helmet made of the composite material, the radius R of the spherical crown is 8.5-11 cm, the height H of the spherical crown is 6-11 cm, and H is less than or equal to R;
warp density lambda of single layer plain woven fabricWarp beam70-165 pieces/10 cm, weft density lambdaWeft yarn70-165 roots/10 cm; the larger the titer of the yarn is, the smaller the corresponding warp density or weft density is;
the warp yarns and the weft yarns are made of para-aramid fibers;
the fineness of the warp yarn or weft yarn is 1000-2500 dtex, the breaking strength is 27.0-35.0 cN/dtex, and the elongation at break is 3.5-4.5%.
In the police helmet made of the composite material, the semi-impregnated aramid composite material prepreg contains 10-14% of modified phenolic resin by mass.
The police helmet made of the composite material has the advantages that the number of the layers is 5-10, and the fit coefficient of the 3D aramid fiber plain cloth is more than 97.3%.
The police helmet made of the composite material has the advantages that the weight of the police helmet is 0.5-0.8 kg, the penetration resistance of the police helmet is high, and the police helmet can bear the penetration of a steel cone of 3kg with the energy of 106J; after the police helmet laterally applies 450N pressure, the maximum deformation is less than 40mm, the residual deformation is less than 12mm, and the helmet shell does not fall off.
The invention also provides a method for preparing the police helmet made of the composite material, which comprises the steps of preparing a modified phenolic resin impregnation liquid according to a certain proportion, immersing the 3D aramid fiber plain cloth in the impregnation liquid, taking out the impregnated aramid fiber plain cloth and airing the impregnated aramid fiber plain cloth at normal temperature until the mass content of volatile matters is lower than 4%, obtaining a semi-impregnated aramid fiber composite material prepreg, and finally taking a plurality of layers of the semi-impregnated aramid fiber composite material prepreg as raw materials to prepare the police helmet;
the preparation method of the modified phenolic resin comprises the following steps: mixing phenolic resin, a modifier and a release agent, adding a diluent, and uniformly stirring to obtain the phenolic resin modified release agent;
the weaving method of the 3D aramid fiber plain cloth comprises the following steps: adopting a plain weaving process, setting a 3D aramid fiber plain cloth weaving area, and setting a corresponding heddle eye height and a corresponding let-off amount when each weave point is formed to prepare the 3D aramid fiber plain cloth;
in a 3D aramid fiber plain cloth weaving area, a calculation method of the heddle eye height and the let-off quantity comprises the following steps:
when (w)i-L/2)2+(vj-D/2)2≥R2(wi-L/2)2+(vj-D/2)2≥R2When the temperature of the water is higher than the set temperature,
hij＝0，sij＝10/λweft yarn；
When (w)i-L/2)2+(vj-D/2)2＜R2When the temperature of the water is higher than the set temperature,
wi＝i×10/λweft yarn；
vj＝j×10/λWarp beam；
Wherein h isijThe heddle eye height (cm), s of a structure point formed by the ith weft yarn and the jth warp yarn when weaving a 3D aramid fiber plain cloth weaving areaijThe method comprises the steps that when a 3D aramid fiber plain cloth weaving area is woven, the warp feeding amount (cm) of a weave point formed by an ith weft yarn and a jth warp yarn is obtained, i is 1, j is 1, n is the number of beating-up times, and n is the number of warp yarns; r is the radius (cm) of the spherical crown, H is the height (cm) of the spherical crown, and L is the length (cm) of a 3D aramid fiber plain cloth weaving area along the warp direction (the length is more than or equal to that of the corresponding 3D aramid fiber plain cloth extending surface along the warp directionLength of both ends), D is the width (cm) of the 3D aramid fiber plain cloth weaving area along the weft direction (length of both ends of the corresponding 3D aramid fiber plain cloth extension surface along the weft direction or more), λWeft yarnIs the weft density, lambda, of the 3D aramid fiber plain cloth weaving areaWarp beamWarp density (each defined as the number of yarns aligned parallel perpendicular to the length direction within a 10cm length) of the 3D aramid fiber plain weave area; w is aiAnd vjIntermediate transition parameters; the units of angles are in radians.
When the 3D aramid fiber plain cloth is woven, grid-shaped supporting bodies with the same spherical crown on the surfaces are placed in a weaving opening corresponding to the weaving speed of the 3D aramid fiber plain cloth to a first row of heddle areas; 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 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. 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.
When the 3D aramid fiber plain cloth is woven, each warp yarn is independently and actively let-off under constant tension.
As a preferred technical scheme:
in the preparation method of the modified phenolic resin, the phenolic resin is S-157 phenolic resin with the solid content of 50-55%, the modifier is polyvinyl formal acetaldehyde (10% ethanol solution), and the release agent is oleic acid; the mass ratio of the phenolic resin to the modifier to the release agent to the diluent is 60-70: 30-40: 1: 40-50.
The preparation method of the police helmet made of the composite material has a certain proportion of 180-190 g/m2；
According to the preparation method of the police helmet made of the composite material, in the weaving method of the 3D aramid fiber plain cloth, before weft insertion, after weft insertion or after beating-up is performed when each tissue point is formed; the thin plate is made of metal;
the independent active warp let-off of each warp yarn is realized by connecting different warp yarns with different warp let-off mechanisms respectively and independently and controlling the warp let-off amount of each warp yarn;
the tension of the warp yarns is 30-100 cN/piece; the tension of the weft yarn is 10-40 cN/root;
the winding speed is 1.4cm-2.6cm/min, and the beating-up speed is 10-18 pieces/min; a tension control and regulation system is arranged at the position of the driving beam, and the uniform tension of the warp yarns can be ensured by controlling the speed of the warp feeding line; 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;
according to the preparation method of the police helmet made of the composite material, 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.
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 3D aramid fiber plain cloth has great advantages in the aspects of integral layering 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 3D aramid fiber plain cloth, the 3D aramid fiber plain cloth is woven by adopting a grid-shaped support body, and compared with a special-shaped roller reeling method in the prior art, 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 method cannot be uniform; 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, weft yarns can be arranged at equal intervals when in beating, the weft yarns are linear in the projection direction of a finished fabric, and when the weft yarns are wound at a constant speed, the weft yarn density 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 plane area (extension surface) of the 3D aramid fiber plain cloth, the warp yarns are interwoven according to a normal woven fabric weaving process; when weaving the curved surface region (spherical crown), according to the curved surface region form, through the control of heddle eye height and let-off quantity, and make the let-off quantity increment of the warp yarn that the curved surface region of different heights is located different, the general principle is: the height of the heddle eyes penetrated by the warp yarns participating in the weaving of the curved surface area is different from that of the heddle eyes penetrated by the warp yarns participating in the weaving of the plane area, and the height of the heddle eyes penetrated by the warp yarns participating 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 participating 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 3D fabric prepared by the grid method has better fitting degree with the designed shape, the existence of the grid-shaped support body enables the fitting effect to be excellent and the variety to be changed more quickly without the need of carrying out optimization on the previous design and detection and correction on the fitting degree in the later period, the fitting coefficient of the 3D fabric prepared by the invention is high, because the grid-shaped surface form determines the form of the final 3D fabric, weft yarns are supported by the support body in the weaving process, and the warp yarns and the weft yarns are interwoven, the warp yarns and the weft yarns can be completely fitted on the grid-shaped support body, so the fitting coefficient of the fabric is close to one hundred percent when the fabric is not taken off, the inevitable problems of shrinkage, wrinkling and the like exist after the fabric is taken off, and the fitting coefficient has small-range change.
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 3D fabric, due to different curvatures of the 3D fabric, the selection of let-off modes is different, specifically: the let-off of the 3D fabric with large curvature is suitable for positive let-off, because the difference of the heald lifting height of the warp yarns of the fabric with large curvature is obvious during weaving, the positive let-off with corresponding let-off amount is respectively carried out on the warp yarns with high heald lifting height and low heald lifting height, and the uniform tension of each warp yarn in the weaving process can be ensured by carrying out differentiated positive let-off on each warp yarn.
The purpose of active let-off is to ensure that let-off amount and tension are controllable and accurate, so as to ensure that the density of the woven 3D fabric is uniform, and the technical requirement on the fit coefficient is realized under the supporting action of the grid-shaped supporting body.
It is important to improve energy dissipation when the helmet is impacted by an external force. Firstly, the aramid fiber adopted by the invention has the characteristics of high strength, high modulus and the like, and the phenolic resin has excellent mechanical property and is an ideal thermosetting matrix resin, so that the impact resistance of the helmet can be obviously improved by adopting the two materials; secondly, the 3D fabric with uniform density and high fit coefficient is prepared by the technical means, the stress can be more uniform due to the uniform density, and the absorption capacity of the helmet on external force impact is improved; meanwhile, the improvement of the fit coefficient can reduce the layering failure effect generated by the helmet under the impact of external force.
Advantageous effects
(1) According to the preparation method of the police helmet made of the composite material, warp and weft yarns can be interwoven on a curved surface by controlling the warp yarn let-off amount and the lifting heddle stroke, and 3D aramid fiber plain cloth with the same warp density and weft density can be prepared;
(2) according to the police helmet made of the composite material, the adopted 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 impact resistance of the helmet is improved.
Drawings
Fig. 1 is a schematic diagram of a 3D aramid fiber plain cloth, wherein (a) is a schematic diagram of a top view of the 3D aramid fiber plain cloth, (b) is a schematic diagram of an ith weft yarn, and (c) is a schematic diagram of a jth warp yarn.
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 weaving method of 3D aramid fiber plain cloth comprises the following steps:
warp yarn: para-aramid fiber, the fineness of which is 2000dtex, the breaking strength of which is 30.0cN/dtex, and the elongation at break of which is 3.8 percent;
weft yarn: para-aramid fiber, the fineness of which is 2000dtex, the breaking strength of which is 30.0cN/dtex, and the elongation at break of which is 3.8 percent;
the weaving method of the 3D aramid fiber plain cloth comprises the following steps: the method comprises the following steps of adopting a plain weaving process, setting a 3D aramid fiber plain cloth weaving area, and setting corresponding heddle eye height and let-off quantity when each tissue point is formed after beating-up to prepare the 3D aramid fiber plain cloth, wherein the method specifically comprises the following steps:
as shown in fig. 1(a), which is a schematic top view of a 3D aramid fiber plain cloth, the 3D aramid fiber plain cloth has a length of L (cm), a width of D (cm), a central spherical crown with a radius of R (cm) and a height of H (H ≦ R) (cm), a center of a bottom circle of the spherical crown is located at a point (L/2, D/2), and a portion outside the spherical crown is a plane;
if the lower left corner point O of the 3D aramid fiber plain cloth is taken as an origin (virtual point), weft yarns and warp yarns are respectively arranged along the length direction and the width direction of the fabric, and the weft density and the warp density are respectively lambdaWeft yarn、λWarp beam(each defined as the number of yarns arranged in parallel in the direction perpendicular to the longitudinal direction within a length of 10cm), and a weave point where the i-th weft yarn and the j-th warp yarn (yarn numbers i and j are positive integers) intersect is P (for the sake of understanding described below, the shapes of the weft yarn i and the warp yarn j when P is located on the spherical crown are shown in FIGS. 1(b) and 1(c), respectively),
let wi＝i×10/λWeft yarn，vj＝j×10/λWarp beamHeight h of heald lifting at point PijAnd let-off amount sijThe calculation method comprises the following steps:
when (w)i-L/2)2+(vj-D/2)2≥R2When the temperature of the water is higher than the set temperature,
hij＝0，sij＝10/λweft yarn；
When (w)i-L/2)2+(vj-D/2)2＜R2When the temperature of the water is higher than the set temperature,
wherein h isijThe heddle eye height s of a structure point formed by the ith weft yarn and the jth warp yarn when weaving a 3D aramid fiber plain cloth weaving areaijThe warp let-off amount of a weave point formed by an ith weft yarn and a jth warp yarn when a 3D aramid fiber plain cloth weaving area is woven is represented by i being 1, m, j being 1, n, m being the number of beating-up times (300), and n being the number of warp yarns (300); r is the radius (cm) (11cm) of the spherical crown, H is the height (cm) (8cm) of the spherical crown, L is the length (cm) (30cm) of a 3D aramid fiber plain cloth weaving area along the warp direction, D is the width (cm) (30cm) of the 3D aramid fiber plain cloth weaving area along the weft direction, and lambdaWeft yarnThe weft density (100 pieces/10 cm) of a 3D aramid fiber plain cloth weaving area is lambdaWarp beamWarp density (100/10 cm) for the 3D aramid fiber plain weave area (each defined as the number of yarns aligned parallel perpendicular to the length direction within a 10cm length); radian is used as a unit of angle;
setting weaving parameters: the tension of the warp yarns is 50 cN/yarn; the tension of weft yarn is 15 cN/piece, the winding speed is 1.6cm/min, and the beating-up speed is 15 pieces/min; 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 3 times of the height of the lifting heddle;
when the 3D aramid fiber plain cloth is woven, grid-shaped supporting bodies with the same spherical crown on the surfaces are placed in the areas from the corresponding cloth fell to the first row of heddles; the grid-shaped support body is formed by connecting a plurality of thin plates (made of metal) 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;
during weaving, when the 3D aramid fiber plain cloth is woven, different warps are respectively and independently connected with different let-off mechanisms under constant tension to independently and actively let off each warp, the heddle eye height of a heddle corresponding to each warp is adjusted before each beating-up, and the heddle is controlled to ascend and descend by a certain height by respectively and independently connecting different heddles with different lifting mechanisms;
the prepared 3D aramid fiber plain weave fabric is a single-layer plain weave woven fabric formed by interweaving warps and wefts; the shape of the single-layer plain woven fabric consists of a spherical crown and an extension surface; the extension surface is formed by extending outwards along the plane where the bottom of the spherical crown is located; 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 fit coefficient of the 3D aramid fiber plain cloth is 97.5%.
The prepared helmet reinforcing cloth is used for preparing a police helmet, and the method comprises the following steps:
(1) mixing and uniformly stirring S-157 phenolic resin with the solid content of 52%, a modifier (polyvinyl formal acetaldehyde), a release agent (oleic acid) and a diluent (ethanol) according to the mass ratio of 65:35:1:40 to obtain modified phenolic resin;
(2) completely immersing the 3D aramid fiber plain cloth into the impregnation liquid, and staying for 3 minutes;
(3) taking out the impregnated 3D aramid fiber plain cloth, and airing at 25 ℃ until the mass content of volatile matters is 3% to obtain a semi-impregnated aramid fiber composite prepreg;
in the semi-impregnated aramid composite prepreg, the mass percent of the modified phenolic resin is 13%;
(4) preparing a police helmet by using 6 layers of semi-impregnated aramid composite prepreg as a raw material;
the weight of the prepared police helmet is 0.7kg, and the police helmet can bear the puncture of a steel cone of 3kg with the energy of 106J; after the police helmet laterally applies 450N pressure, the maximum deformation is 38mm, the residual deformation is 11mm, and the helmet shell does not fall off.
The 3D aramid fiber plain cloth can realize the primary weaving of the complex curved surface form of the fabric, and avoids the defects of discontinuous warp and weft yarns, non-uniform warp and weft density and defective use effect caused by the procedures such as folding, cutting, sewing and the like adopted in the secondary three-dimensional modeling; and the helmet made of the material has light weight and good impact resistance.
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